Band 12, Heft 1

To enhance the productivity of horizontal wells, it is of necessity to ensure that they perform optimally. This requires an understanding of how the reservoir’s geometry, anisotropy and well design affect the pressure response. Mathematical formulations can be used to simulate pressure response in the wellbore and the data obtained can be analysed to obtain well and reservoir parameters that can aid performance and evaluation. In this study, a mathematical model that can be used to approximate pressure response in a horizontal well is formulated, and a detailed mathematical analysis that can be used to obtain well and reservoir parameters are provided. A horizontal well inside a rectangular drainage volume with sealed boundaries is considered and the effect of each boundary on pressure throughout its productive life is studied. In the analysis, investigations on how the reservoir parameters can be approximated over a given period of production are conducted. This is achieved by identification of the appropriate source and Green’s functions. These source functions allow us to formulate a mathematical model for dimensionless pressure. Considering the diagnostic plots for both dimensionless pressure and dimensionless pressure derivative, mathematical analysis studies the possible behaviour of the plots. Analysis indicates that the reservoir anisotropy can be approximated during the infinite-acting flow at early times when other parameters are known. Further, when the first boundary is felt, in this case the vertical boundary, the horizontal permeability can be approximated during the transition flow periods at middle times. Finally, at late times when all the boundaries have been felt and a pseudosteady state flow is evident, reservoir dimensions can be approximated. These results can significantly improve well test analysis and enhance the performance evaluation of a horizontal well.

This study deals with the subject of the Fourth Industrial Revolution; that is, Industry 4.0 or Revolution 4.0 discusses its impact on contemporary road transport and the development of Transport 4.0. The needs of the industry as well as the transport industry change diametrically with the correspondingly sudden and rapid development of technology, as well as the requirements of companies hiring new employees. To meet the future requirements of Revolution 4.0, the vocational training program should undergo a major overhaul. Therefore, it is important to determine what skills and qualifications of employees of transport companies should be currently developed. The study presents fragments of analyses performed as part of the F2J – “Future-Ready Ed Right Skills To Right Job” project, financed by the European Commission under the Erasmus + Program. The main goal of this article is to identify the skills and characteristics of transport companies’ employees that are most required from the point of view of the Revolution 4.0. Both technical and soft skills to be imparted into the human workforce for Transport 4.0 were reported. Study shows the need to address the integration of the concept of Revolution 4.0 into the current education system. The article is based on the analysis of data from highly qualified employees who work in transport companies (practitioners), as well as people involved in education and comprehensive preparation of people for work in the transport industry (educators). A total of 63 people participated in the study.

Seismic measuring stations do not only record seismic waves. They also pick up tremors caused by other factors: these are known as seismic background noise. In normal conditions, this environmental background is steady over a long time. This article presents the influence of high reduction of human activity due to COVID-19 initial lockdown on ground vibration in the Large Hadron Collider tunnel at the European Organization for Nuclear Research.

This article presents the results of analytical and numerical research focused on the numerical determination of selected fracture mechanics parameters for beams containing a crack in the state of four-point bending with the dominance of a plane strain state. Based on the numerical results, the influence of the specimen geometry and material characteristic on selected fracture parameters is discussed. By analogy to the already known solutions, new hybrid formulas were presented, which allow to estimate the J integral, crack tip opening displacement, and load line displacement. In addition, the study verified the Shih formula connecting the crack tip opening displacement and J integral, taking into account the influence of in-plane constraints on the value of the proportionality coefficient denoted as d n in the analysis. This article also presents the development of Landes and Begley’s idea, which allows to experimentally determine the J integral as a measure of the energy causing the crack growth. The innovative element is taking into account the influence of in-plane constraints on the value of the η coefficient, which is the proportionality coefficient between the J integral and energy A . The last sections of this article are the assessment of the stress distribution in front of the crack tip and the selected measures of in- and out-of-plane constraints, which can be successfully used in the estimation of the real fracture toughness with the use of appropriate fracture criteria.

For additive manufacturing (AM) to be successfully implemented in manufacturing systems, the geometric accuracy of components must be controlled in terms of form, fit, and function. Because the accuracy of AM products is greatly affected by the part build orientation, this factor dictates the achievable tolerances and thereby the ability to incorporate AM technologies in a large-scale production. This article describes a novel optimization method for minimizing form errors based on the geometric features of the part. The described method enables the combination of separate expressions for each feature to create a continuous solution space. Consequently, the optimal part build orientation can be precisely determined based on a mathematical description of the effect of build direction on each surface type. The proposed method is demonstrated in two case studies by step-by-step descriptions including discussions on viability and possible extensions. The results indicate good performance and enable flexible prioritization and trade-offs between tolerance characteristics.

This article presents the research which resulted in the creation of the method of automatic selection of adaptive devices for the needs of drivers with motor disabilities – ASA System. An expert system was used to build the method, which used databases from various fields of knowledge in the inference process. The databases were created on the basis of an analysis of the literature on the mobility of people with disabilities, a review of the operation of companies specializing in adaptations, verification of adaptive devices in terms of their functions, as well as various categories of disability. The knowledge of the individual selection of adaptive devices and expertize in this area made for specific recipients were used. Based on the accumulated knowledge, a simplified division of adaptive devices and classification of disabilities were implemented. The conclusions from analyses made it possible to formulate the rules necessary for the application process. A comparative analysis of the degree of consistency between the selection of devices generated by the ASA System (automatically) and the selection made by three experts (individually) for 44 people with various motor disabilities, was carried out. The results obtained confirmed usefulness of the expert system in building the method of automatic selection of adaptive devices, as well as the rightness of automating this process, due to the objectivity of the proposed method in comparison with individual, subjective selection carried out by experts.

Over the last decade, the increase in the number of vehicles has affected traffic performance, causing traffic congestion. However, intersections, where different flows intersect, are among the primary causes of traffic congestion besides bottlenecks. Bottlenecking in the minor stream is mainly due to the extended queueing, specifically due to minimal gaps in the mainline stream as the intersection’s high priority exists with the major stream. This research aims to control connected and automated vehicles (CAVs) to help generate additional usable gaps for the minor road vehicles to enter the intersection without interrupting the mainline traffic flow. A probability function is developed to estimate the probability of CAVs creating additional usable gaps. The proposed logic is simulated in unsignalized and semi-actuated signalized intersections, and a field investigation is conducted. Simulation results show that the minor road delays and queue length are minimized without causing a significant delay to the mainline. Results show that major road interruptions are reduced at a semi-actuated signal control scenario when CAVs’ penetration increases. It can be observed that deploying CAVs in the road network with the proposed method can positively impact traffic efficiency, where the intersection’s performance and safety are improved.

Energy-saving and emission reduction are crucial since shipping activity due to the global maritime trade has increased exponentially. Several agreements have been engaged to optimize ship energy efficiency composed of ship design and shipping operation planning. However, most up-to-date studies focused on speed and route optimization. The interaction analysis between speed and route efficiency below varied environmental conditions is limited. To attain energy and cost efficiency, a study of cavitation on the propeller that considers the ocean environmental condition will be discussed in this work. Although researchers have previously observed cavitation phenomena, the predictability of simulations is not yet such that problems can be eliminated. Since the multiphase flow of water and vapor is sensitive to environmental conditions, it leads to varying observation accuracy. Thus, the current paper proposes a new performance indicator of the ship propeller under cavitation predicted by computational fluid dynamics (CFD). CFD-based simulation to observe the propeller cavitation was used to model the Zwart cavitation and Kunz cavitation models under two turbulence models of K − ε at different flow conditions and operating environments. Initial validation tests between experimental and numerical simulation show good agreement with a mean error of 4.7% in the Zwart model and 3.7% in the Kunz model, where the k − ε turbulence model provides an almost higher relative error. It is revealed from the result that the increase in temperature causes the rise in the cavitation problem. It is revealed from the result that the increase of temperature causes the increase in cavitation problem.

The primary goal of this article is to implement a dual reciprocity boundary element method (DRBEM) to analyze problems of rotating functionally graded anisotropic fiber-reinforced magneto-thermoelastic composites. To solve the governing equations in the half-space deformation model, an implicit–implicit scheme was utilized in conjunction with the DRBEM because of its advantages, such as dealing with more complex shapes of fiber-reinforced composites and not requiring the discretization of the internal domain. So, DRBEM has low RAM and CPU usage. As a result, it is adaptable and effective for dealing with complex fiber-reinforced composite problems. For various generalized magneto-thermoelasticity theories, transient temperature, displacements, and thermal stresses have been computed numerically. The numerical results are represented graphically to demonstrate the effects of functionally graded parameters and rotation on magnetic thermal stresses in the fiber direction. To validate the proposed method, the obtained results were compared to those obtained using the normal mode method, the finite difference method, and the finite element method. The outcomes of these three methods are extremely consistent.

Corrosion resistance of untreated (B265TiN), quenched (B265TiQ), and annealed (B265TiA) B265 titanium alloy was studied in 2–10 M H 2 SO 4 + 10% NaCl solution at 30, 70, and 95°C by potentiodynamic polarization, potentiostatic measurement, open circuit potential measurement, and optical microscopy. B265TiN was the most resistant of the alloys to general corrosion at 30°C with values between 0.094 and 3.782 mm/year. B265TiQ exhibited the highest corrosion rate values (0.210–23.399 mm/year). Its plots show significant increase in cathodic slope. At 70 and 95°C, B265TiN exhibited the lowest corrosion rate in 2 and 6 M H 2 SO 4 + 10% NaCl solution, while B265TiQ exhibited the corresponding highest values. Optical characterization shows B265TiN, B265TiQ, and B265TiA alloys are highly resistant to corrosion in 2 M H 2 SO 4 + 10% NaCl at 30°C compared to 10 M H 2 SO 4 + 10% NaCl, where marginal deterioration occurred on B265TiN, significant degradation on B265TiQ, and localized degradation on B265TiA. The extent of degradation increased at 70 and 95°C. B265TiN exhibited the highest resistance to metastable pits formation compared to B265TiQ and B265TiA. Potentiostatic values at 70°C shows high temperature exposure of Ti alloy to accelerated corrosion. Metastable pit initiation values at 70°C are significantly greater. Open circuit potential measurement at 30°C shows B265TiN demonstrated least vulnerability to corrosion with stable oxide formation at 2 M and 6 M H 2 SO 4 + 10% NaCl, and B265TiQ was least vulnerable at 10 M H 2 SO 4 + 10% NaCl. At 70°C, B265TiQ was least vulnerable to corrosion with unstable oxide formation at 2 M and 6 M H 2 SO 4 + 10% NaCl compared to B265TiN at 10 M H 2 SO 4 + 10% NaCl.

Vibrating conveyors tend to transfer dynamic forces to the ground. One way to vibroinsulate such systems from the environment is to use dynamic methods to eliminate vibrations. Due to this phenomenon, the forces transferred to the ground are reduced. This article attempts to identify important elements determining the design of an antiresonance-type conveyor. The study of dynamic phenomena was based on two models of such conveyors with two and six degrees of freedom (with the phenomenon of self-synchronization). In this work, the impacts of various types of suspension and the ratio of the body mass to the mass of the conveyor trough on forces transmitted to the ground are analysed.

Background The problem of ballast water is caused by microorganisms. The solution to solve this problem is ballast water disinfection. Until the recent day, there have not been many practical solutions. Usually, ozone, chlorine, and UV treatments were used for disinfection. However, these methods still have many weaknesses in treating ballast water. Methods The ferrate( vi ) system proposed in this paper is liquid ferrate( vi ) produced on-site using a slow-released system and combined with ultrasound. This paper investigated the optimum time to produce liquid ferrate( vi ), pH, and temperature. Results The optimum synthesis time has been observed to be 10 min with the produced ferrate( vi ) of 42,000 ppm. The optimal pH and temperature to make ballast water harmless have been observed to be the neutral pH condition at 25°C, respectively. The design of ballast water treatment using ferrate( vi ) combined with ultrasound has also been proposed in this paper. Conclusions Ferrate( vi ), as the primary material in ballast water treatment, has been successfully synthesized. The process of ballast water treatment using ferrate( vi ) combined with ultrasound can be performed automatically using a time sensor and a mass sensor. With the proposed design, it can be a promising solution to solve the problems related to ballast water.

The article presents the results of research on the influence of whole body vibrations (WBVs) on a person moving in a wheelchair. The tests were carried out using an electrohydraulic shaker for a kinematic harmonic excitation with a constant amplitude and frequencies, respectively, 2, 5, 10, 15, and 20 Hz. The accelerations caused by vibrations were measured with three-axis accelerometers at three measuring points: on the seat, chest, and head of the examined person. The research included frequency and statistical analyses of vibrations. The analyses were focused on the course of the transition functions over frequency. The range of the disabled person’s exposure to the negative factor which is WBVs was assessed.

The derivation of real accident scenarios from accident databases represents an important task within vehicle safety research. Simulations are increasingly used for this purpose. Depending on the research interest, a wide range of accident databases exists worldwide, which differ mainly in the number of recorded data per accident and availability. This work aims to identify critical vehicle-to-vehicle accidents based on freely available accident databases to derive concrete scenarios for a subsequent simulation. For this purpose, the method of the pre-crash matrix is applied using the example of the freely available Crash Investigation Sampling System database of the National Highway Traffic Safety Administration. An analysis of existing databases worldwide shows that this is the most detailed, freely available database. The derivation of scenarios succeeds here by a new method, whereby a center of gravity calculation is carried out based on the damages of the vehicles according to Collision Deformation Classification nomenclature. In addition, the determination of other necessary parameters, as well as the limits of the database, is shown in order to derive a scenario that can be simulated. As a result, the constellations of the five most frequent vehicle-to-vehicle accident scenarios according to the Crash Investigation Sampling System database are presented. In particular, other institutions should follow National Highway Traffic Safety Administration’s example and make data freely available for accident research.

This research aims to find a new way to address thermal loads within the framework of the elastic–plastic relationship, especially when the loads, such as thermal and pressure ones, are combined. While the residual force method was employed to attempt to find the convergence of a nonlinear solution, it was unable to do so. For this purpose, a mathematical relationship was derived to address thermal loads and add them to the hierarchy of the specified elements method as a subroutine. The findings of the developed program were verified by comparing the numerical results with those of the analytical solution of a thick-walled cylinder loaded with heat load and internal pressure; the results proved the correctness and accuracy of the method used. The method offers a way to redevelop old programs that are unable to effectively address the thermal load in elastic–plastic relations without changing said programs significantly but only by adding the subroutine and some very simple modifications. The solution technique provided in this article can be utilized in many related cases, such as plane stress, axisymmetric solid, and three-dimensional stress analyses.

Websites must assure web server availability in light of the worldwide increase in internet users. Web server monitoring is the process of examining web application server utilization by showing data in the form of statistics or graphs. Data about web server use will help server owners make decisions about server availability. The purpose of this study is to create a web monitoring program capable of retrieving and storing data from Java application server resources. The research methodology utilized in this study is divided into two phases: data gathering and software development. The data gathering step includes doing a literature study, conducting a survey, distributing questionnaires, and analyzing comparable apps. The development phase employs the waterfall methodology. The outcome of this study is a web application that can monitor the Java application server’s resource use and send email alerts when resource usage becomes excessive. To summarize, web application server monitoring may be utilized to alleviate developer workload.

This article presents a developed lightweight data encryption algorithm called LBC-3. Its essential difference from the known algorithms is the R1 function and the procedure for generating round keys. The main characteristics of this lightweight algorithm and all the transformations used in the encryption and decryption processes are described. The process of generating the round keys of the algorithm is also considered. The results of the study of the cryptographic properties of the algorithm using the “avalanche effect” and statistical tests are presented. The avalanche property was tested for each round with each bit of the source text changing. Based on the work carried out, it was found that the proposed encryption algorithm is effective in providing a good avalanche effect, and the binary sequence obtained after encryption is close to random. The research revealed good cryptographic properties of this algorithm.

The COVID-19 pandemic significantly affected the performance of the transport sector and its overall intensity. Reducing mobility has a major impact on road traffic accidents. The aim of this study is to forecast the number of road traffic accidents in Poland and Slovakia and to assess how the COVID-19 pandemic affected its trend. For this purpose, data for Poland and Slovakia in the selected relevant period were analyzed. Based on actual data from the past, a forecast was made for the future considering two scenarios – one where there is no effect of pandemic, and another with effect of pandemic. Forecasting the number of accidents in Poland was carried out using selected time series models related to linear trend (Holt and Winters method) and the exponential model. In the case of Slovakia, the model without trend and the exponential model were used to forecast the number of traffic accidents. The results of the research show that the pandemic caused a decrease in the number of traffic accidents in Poland by 31% and in Slovakia by 33%. This is a significant decline, but it is linearly dependent on restrictive measures that affect the mobility of the population. A similar trend can therefore be expected on a European scale.

The purpose of this work is to develop and implement a disaster recovery plan (DRP) in stock exchange industry in Indonesia, in order to perform a system recovery in the event of a disaster. To develop a DRP, there are several steps that must be performed as a risk analysis to determine how much risk the company would receive when a disaster occurs, business impact analysis to identify critical business units and necessary resources for the recovery process to run smoothly, to identify recovery strategies to be used as a backup method and recovery site, the recovery procedure that needs to be done in order to make the recovery process run properly, testing and review, and documentation of the DRP. Based on the results of tests that have been done, the development of DRPs can be implemented at stock Exchange industry in Indonesia. With the DRP, the company is expected to have a plan to prepare for and recover resources and information systems in order to be able to walk back in the event of a disaster in order to minimize losses to the company.

The article presents a new method of predicting the yield-lines of statically loaded slabs, based on roof geometry (straight skeletons) and Voronoi diagrams for a polygon. A surprising analogy was found between the layout of the plate’s yield-lines and the edge lines of the embankments created as a result of the free falling of loose material onto the plate-shaped polygon. According to the proposed method, the yield-lines have the shape not only of segment lines, but also parabolas (in 3D interpretation also hyperbolas). The method proposed here is purely geometric and can be used to pre-determine the shape of the yield-lines. It allows to predict the shape of the grid of the yield-lines for plates with various support methods, including point support. In addition, the method is relatively simple and can be implemented in the standard CAD software environment. However, the method requires knowledge of descriptive geometry in the field of roof skeletons design (straight skeletons) and roofs with restriction.

Transportation in cities may undergo substantial changes due to two emerging technologies that enable three-dimensional movement of people or cargo. These emerging technologies are urban air mobility (UAM) and flying cars. The present study gives an overview of both technologies, differences and similarities between them, challenges they face, the opportunities they bring, and examples for them with varying stages of readiness from being commercially available to being a concept in development having a small-scale prototype. The models covered here include EHang 216 (UAM aircraft), VoloCity (UAM aircraft), PAL-V Liberty Sport (flying car), and ASKA (flying car). Focusing on air taxis (or flying taxis) in the form of a fleet of piloted or autonomous electric vertical takeoff and landing aircraft operated commercially by a corporation that provides mobility as a service, a discussion about the prospects of this nontraditional mode of transportation is provided, with anticipated drawbacks and proposed solutions.

This article provides an effective method of determining the coordinates of points and the angles for various surfaces approximating the ellipsoid surface. The stands of the stadium (with a capacity of up to 82,000 seats) with rows shaped by ellipse arcs were designed (in accordance with the European Standard EN 13200-1). An algorithm was proposed to determine the optimal height of the ring steps (with the guarantee of unobstructed vision of the entire playing field from each seat of the stands). The second algorithm ensures a comfortable space in each individual seating place in the stands (deviation of the depth of the row generated by ellipse arcs did not exceed 0.000009 m at any place of the stands). This article encourages readers to program DXF files (read in the AutoCAD system) to streamline design work.

Hydraulic structures such as sluice gates are more sensible of driftwood that is transported by a river; all this debris, like a trunk, deadwood, and rootstocks, can be accumulated upstream hydraulic structures may cause many hydraulic troubles, so studded such as these phenomena more essential to prevent or reduce its effects on these structures. Many studies dealt with the impact of driftwood on scouring around piers and weirs and its hydraulics, but the studded dealt with sluice gate structures are few and still need deep studies. This study dealt with the sensitivity of driftwood blocking flow under a sluice gate. It found that a large gate opening and 50% of the maximum upstream head lead to a decreased probability of trapped index and an increasing likelihood of driftwood passage beneath the sluice gate, which causes scour if driftwood is blocked under a sluice gate, so this case must be avoided. The driftwood trap probability of rootstock is greater than the trunk, and accumulated driftwood causes an increasing upstream water depth by 15%. Increasing its volume increases trapping probability.

Renewable energy sources are considered ubiquitous and drive the energy revolution. Energy producers suffer from inconsistent electricity generation. They often struggled with the unpredictability of the weather. Thus, making it challenging to balance supply and demand. Technologies like artificial intelligence (AI) and machine learning are effective ways to forecast, distribute, and manage renewable photovoltaic (PV) solar supplies. AI will make the energy forecasting system more connected, intelligent, reliable, and sustainable. AI can innovate how energy is used and help find solutions for decarbonizing energy systems. There are potential advantages to total energy forecasting. AI can support the growth and integration of PV solar energy. The article’s main objective is to use AI to forecast the output consumed power of the Yarmouk University PV solar system in Jordan. The total actual yield is 5548.96 MW h, and the performance ratio (PR) is 95.73%. Many techniques are used to predict the consumed solar power. The random forest model obtains the best results of root mean squared error and mean absolute error are 172.07 and 68.7, respectively. This accurate prediction allows for the maximum use of solar power and the minimal use of grid power. This work guides the operators to learn trends embedded in Yarmouk University’s historical data. These understood trends can be used to predict the consumption of solar power output. Thus, the control system and grid operators have advanced knowledge of the expected consumption of solar power at each hour of the day.

This article presents the performance of cable-stayed bridge by representing a model using the ANSYS program under the influence of a concentrated load and then comparing them with the experimental results. One model was used in the analytical, and one was (harp type 1) used in the length of the girder (4,500 mm), height of the pylon (1,480 mm), and depth of the flange for the girder (40 mm). If cable-stayed bridges are constructed using the balanced cantilever method, the stability problem of the girder is more significant during the construction stage than at the initial state. In this study, to investigate the ultimate behavior of cable-stayed bridges, experimental and analytical studies were conducted for one model: Harp type 1. At the limit state, several plastic hinges occurred and the girders buckle along the entire span. Numerical analysis was conducted for the experimental model, and the results of which showed good agreement with the experimental results. The influence of such kind of effects on the analysis and the structural behavior of cable-stayed bridges has been examined in detail in the study. The dimensions of the model were also compared with institute civil engineering Code in terms of the height of the tower to the main space, and Back Span to the main span ratio. It was close to standard specifications. A finite element procedure for the nonlinear analysis of cable-stayed bridges is first set up, and then, a detailed static deflection analysis of such bridges is carried out.

This article displayed the method of partial discharge (PD) measurement in high-voltage insulator and calibrating the effective element (capacitor) to enhance the PD signal. The cavity shapes were plate–plate, cylindrical and spherical inside the solid insulator. The proposed system enables from detecting the reverse and main discharge, respectively, through the rise and tail time of the pulses. PD that took place was bounded with internal cavities. Proteus simulator and Matlab simulation models were used to measure and display the PD signal. The results showed PD-calibrated waveforms and the voltage values across the cavity ( V c ). Finally, this work concluded that the spherical cavity shape gave a higher value of the calibrated capacitor and lower voltage across the cavity ( V c ) for both models.

The possible adverse health effects of electromagnetic field (EMF) exposure have been in research focus since radio waves were introduced to telecommunication. Broadcast radio systems, satellites, and mobile communication devices use different bands of the radio spectrum, antennas, modulations, and radiated power. The proliferation of cellular networks and mobile phones as user devices have brought transmitting and receiving antennas in the close proximity of the human body and the head. Hundreds of experiments have been conducted to prove and disprove adverse health effects of exposure. Literature reviews of experimental results have also followed the current developments in technology; however, an exhaustive analysis performed on the methodologies has revealed many flaws and problems. This article focuses on the latest results on frequency bands mostly used for 5G below and above 6 GHz in the mmWave band. Current results do not indicate significant health effects and responses below the current safety limits. Nevertheless, further research directions can be identified, especially for mmWave radiation.

The growing paste of military operations, as well as the increased involvement of the Armed Forces in countering the ramifications of natural disasters, impacts the design solutions used for military bridging systems. The most vital optimization factor is the speed of deployment to which all the structural solutions are subject. Another determinant is a wide range of the parameters of the gap to be crossed using one bridging structure transported using typical means of transportation, including its width and the height of the banks. There is a worldwide tendency to fill the space between the treadways, making them more solid and thus much more usable for civilian vehicle traffic as well. That in turn makes them a provisional replacement for the damaged bridge infrastructure used by the population. This poses a number of challenges to be tackled by the state-of-the-art line-of-communication (LOC) bridges and both the close- and general support bridges, which seem to assume the tasks of the LOC bridges.

The impact of human activity on the environment is an ongoing concern not only in the natural sciences but also in economics. Special attention is focused on the transport system, which is one of the largest producers of so-called externalities. However, its regulation may mean a serious disruption of global logistics links, which are crucial for maintaining international and national trade, gross domestic product formation and, therefore, to maintain the economic level to which mankind is accustomed to and which brings a quality of human life that is the highest in the human history. The article, therefore, examines possible economic approaches and theories to the problem of the relationship between human activity and the environment and the possible reduction of negative externalities. Typical approaches to dealing with externalities include the theories of the English economist Arthur Pigou, who proposed the application of various taxes and subsidies to limit the so-called social costs, whereas the extreme solution is the explicit prohibition of certain activities. In contrast to this approach is the theory known as the environmental Kuznets curve, which states the relationship between environmental damage and the economic performance of a given geographical area. It must be respected that the reduction of negative externalities, or their so-called internalisation, cannot be expected to be a trivial solution. The application of additional taxes or subsidies can lead to many unintended consequences, which may ultimately have a greater negative economic impact than the externalities themselves. Therefore, the conclusion of this article is devoted to a discussion of the potential risks of such regulatory interventions from the government position.

The study focuses on the issue of parking in Olomouc and in two localities of this city: the Foerstrova and Hodolany areas. In the first part of the manuscript, general data, approaches, and methods regarding the process of designing parking areas as well as the demand forecasting for parking spaces, when explaining the principles of regression analysis itself, are presented. The second part of the article, which represents a crucial section of the conducted research study, discusses the very analysis of the parking situation and parking demand forecasting for both areas being investigated. As for major findings, an increasing trend related to the number of cars per 1,000 inhabitants in Olomouc can be observed. Furthermore, following the performed analyses and forecasts, it can be stated that there is a parking deficiency issue, which needs to be addressed in the future.

The article deals with traffic accident rates in the Czech Republic and activities of the basic component parts of the integrated rescue system in relation to traffic accident addressing. On the basis of statistical data from the period 2011 to 2018, the purpose of the main component parts of the integrated rescue system in providing aid to victims of traffic accidents is emphasized. A real traffic accident is used to describe the intervention procedure with an emphasis on disentangling individuals from wrecked motor vehicles and provision of pre-hospital emergency care. Assessment of traffic accidents and the methods of their addressing are summed up in proposals for the safe rescue of victims, provision of (first) aid, and elimination of intervention-related complications.

Low voltage cable is primarily connected from the transmission system to several household applications. It is quite common that switching transient in the power system during the energization of the high voltage and low voltage cables have a very crippling effect on the cable as well as the power system components. Hence, an experiment has been performed in the laboratory with a low voltage cable-connected motor system. The experimental results have been validated in the simulation platform, and they are capable of predicting the transient behavior during power cable energization. The effect of transients on power cables during the energization of devices has been investigated in this study in the form of voltage, current, and frequency. Discrete wavelet transform is implemented for the decomposition of the transient current. The generated approximation signal is used to quantify the severity during switching transient condition.

This article validates the operational effectiveness of a fuzzy-based multistage cascaded proportional integral derivative fractional filter (PIDFN) controller which enhances the frequency regulation of an interconnected islanded microgrid system. The effect of the ambiguous nature of renewable energy resources and test cases concerning different load variations are applied to verify the robustness of the proposed controller. The superiority of the proposed controller upon proportional-integral-derivative (PID), fractional-order PID (FOPID), and Fuzzy FOPID controller in minimizing frequency alteration has been verified through MATLAB/SIMULINK environment.

The fabricated inkjet-printed coils (IPCs) are a suitable candidate for near-field wireless power transmission (WPT) to the next generation of high-performance implantable medical devices with extreme size constraints that will target intraocular and intracranial spaces. It is a challenging task for anyone to design an efficient inductive link for power transmission as, the secondary coil (receiver element) is placed 3 mm under the skin surface. This paper focuses on an analytical comparison among the basic four topologies of the WPT system in terms of compensation requirement and power efficiency. Hence, designers can choose the best possible topology depending on the coupling coefficient, coil design, and load impedance. In this work, the printed coil is designed with 10 layers of 10 μm thickness, respectively, in both cases. The effect of IPCs on the secondary side is briefly analyzed by considering the parasite resistance of the coil for compensation; the behavior of the system is not significantly affected by using the printed coils for compensation on the primary side. As the compensating capacitance does not depend on the parasite resistance, the series–series topology is preferable for the WPT system. The efficiency decreases due to the presence of parasite resistance in the printed coils. Moreover, it is required to choose an efficient topology as the efficiency varies from 56% to only 38%.

Renewable energy sources like solar power are the more convenient source of renewable energy. Nowadays, increasing the energy demand may create many disturbances in power system distribution. To overcome the necessity of power demand, all are focusing on generation of more energy from clean technologies with increased development in power distribution systems using the renewable energy sources. This work aims to propose a standalone PV system with an LCL filter, with two cascaded feedback control loops with an appropriate controller for three reference frame. This work concerns the topology for three reference frames such as synchronous, standalone, and natural reference frames with the respective controllers (PI and PR). The topology contains two cascaded feedback control loops such as DC-link voltage control loop (PI) cascaded with the internal current loop (PI and PR). These commonly used controllers are implemented in various well-known reference frames for the PV system and their steady-state performance is also evaluated in terms of total harmonic distortion. Finally, the simulation results from a two-stage 5.5 kW, 440 V (L–L), three-phase standalone PV system are provided to confirm the theoretical analysis and effectiveness of the control schemes.

Medical waste incinerator of Al-Sadar hospital in Najaf city is one of the environmental pollution sources in the city due to reasons related to the quantity and quality of gases emitted from it, so this study aims to estimate environmental damage by determining the concentrations of some of these emitted gases. The study is concerned with determining the concentrations of six gases over five months (November 2013–March 2014), these gases were oxygen (O 2 ), silane (SiH 4 ), hydrogen (H 2 ), sulfur dioxide (SO 2 ), nitrogen dioxide (NO 2 ), and hydrogen sulfide (H 2 S), in addition to studying some weather factors such as wind speed and temperature that affect on the concentrations of the gaseous pollutants. It is found that the study area suffers from pollution with SO 2 gas, which is one of the main standard pollutants for assessing polluted areas, where the mean of gas concentration during the study period was 0.205 [ppm] and thus exceeded the permissible limits. Moreover, some of the studied gases (like NO 2 and H 2 S) have concentration close to the upper limit of the standards, where NO 2 gas concentration in December and January were 0.17 [ppm] and 0.2 [ppm], respectively, and H 2 S gas concentrations in February and March were 3.5 [ppm] and 4.4 [ppm], respectively, which poses a threat to public health and other elements of the environment, which confirms the existence of an air pollution problem that the study area and the nearby areas suffer from.

Three scaled concrete slabs were cast and tested till failure under drop-weight impacts and static loads, sequentially. Two of the three slabs contained 0.5% steel fiber while the third slab was constructed by using only steel bar reinforcement (i.e., ordinary reinforced concrete). The obtained data from the testing program were used to distinguish between the performance of traditional reinforced concrete and steel fiber concrete slabs under impacting and static weights and to establish a data base for the upcoming studies pertaining to this research area. The test results and observations showed that the extension of steel fiber to the ingredients of concrete was efficient in decreasing crack widths and softening local damage under dynamic and static loads. On the other hand, reinforcement was more effective in increasing slab capacity than steel stiffeners, consequently different failure modes were observed.

Estimating groundwater salinity is important for the use of groundwater resources for irrigation purposes and provides a suitable guide for the management of groundwater. In this study, the artificial neural networks (ANNs) were adopted to estimate the salinity of groundwater identified by total dissolved solids (TDS), sodium adsorption ratio (SAR), and sodium (Na + ) percent, using electrical conductivity, magnesium (Mg 2+ ), calcium (Ca 2+ ), potassium (K + ), and potential of hydrogen (pH) as input elements. Samples of groundwater were brought from 51 wells situated in the plateau of Najaf–Kerbala provinces. The network structure was designed as 6-4-3 and adopted the default scaled conjugate gradient algorithm for training using SPSS V24 software. It was observed that the proposed model with four neurons was exact in estimating the irrigation salinity. It has shown a suitable agreement between experimental and ANN values of irrigation salinity indices for training and testing datasets based on statistical indicators of the relative mean error and determination coefficient R 2 between ANN outputs and experimental data. TDS, SAR, and Na percent predicted output tracked the measured data with an R 2 of 0.96, 0.97, and 0.96 with relative error of 0.038, 0.014, and 0.021, respectively, for testing, and R 2 of 0.95, 0.96, and 0.96 with relative error of 0.053, 0.065, and 0.133, respectively, for training. This is an indication that the designed network was satisfactory. The model could be utilized for new data to predict the groundwater salinity for irrigation purposes at the Najaf–Kerbala plateau in Iraq.

The issue of global warming has negatively affected the global climate, which caused a decrease in the amount of precipitation and a significant increase in temperatures and evaporation rates. Iraq suffers from poor rainfall, which exacerbates the problem of declining water levels in rivers and the drying up of some tributaries. The Euphrates river, which passes through the eastern side of the Al-Najaf Governorate, is the case study in the current research. A statistical downscaling model is created for rainfall data from 2010 to 2020 with the aim of predicting the future precipitation biennially from 2022 to 2028. The model is calibrated and reflects close results with observations with high accuracy and reliability. The future precipitation levels are transformed after multiplying these levels by the total surface areas of the Euphrates river and its tributaries, and the value of future flowrates to be added to the Euphrates river is estimated. The results showed that the Euphrates river will receive a flowrate of 1,535,945 m 3 in 2026, which is the highest value when compared with the values of flowrate for the years 2022, 2024, and 2028, which are estimated at 1,475,072, 1,456,037, and 1,378,403 m 3 , respectively.

Developing and assessing the performance of water projects and irrigation networks is based on many factors, such as flow measurement. Weir and gate structures have been extensively utilized for flow measurement and to get rid of sediments. The process of modeling and estimating the coefficient of discharge in the weir is an essential part of hydraulic engineering. Recently the application of computer skills was adopted instead of traditional methods. In the present study, the artificial neural network (ANN) was adopted to estimate the coefficient of discharge for a combined weir that consisted of the trapezoidal weir and rectangular gate. For this purpose, the experimental data were collected and analyzed. The dimensional analysis was used to identify the effective dimensionless parameters related to the discharge coefficient. The developed ANN network structure was designed as 6-10-1 and adopted the default scaled conjugate gradient algorithm for training using SPSS V24 software. It was found that the proposed model with ten neurons was highly accurate in predicting the discharge coefficient. The sensitivity analysis was adopted to assess the performance of the ANN using different numbers of effective input parameters. Assessing five models, the ratio of upstream head to gate height ( H / d ), slope of trapezoidal angle (tan  θ ), and the ratio of distance between weir and gate and gate height ( y / d ) parameters are adequate for estimating the discharge coefficient compared to other parameters. ANN model with input parameters of H / d , h / d ( h is the flow depth over the trapezoidal weir), b g / d ( b g is the gate width), tan  θ , b g / b ( b is the total width of flume), and y / d shows reasonable accuracy with acceptable statistical indicators, coefficient of determination ( R 2 = 0.87), relative error (RE = 0.096), and mean squared error (MSE = 1.86) for the discharge coefficient. The ANN model gave a good idea about which factors are more effective on the discharge coefficient, and the process of training the network is more accessible than the traditional method which represent the discharge coefficient by equation.

Existence of potable water is considered as one of the important issues that are related to the survival of human life, especially in fresh water scarce areas. So, it is necessary to find a solution to this problem. In the current work, the productivity of fresh water in conventional single-slope single-basin solar still is increased by using two modification methods. The first method is reflecting the solar ray to the still basin by using aluminum foils that are pasted on the interior surfaces of the still walls. This method will enhance the fallen solar rays on basin water and reduce heat losses. The second method increases the evaporation surface area by introducing blackened stainless steel balls with different diameters at the still basin. Balls of two diameters chosen: 5 and 10 mm. The experimental results show that the productivity of solar still with 10 mm-diameter balls is higher than that of the conventional solar still by 38.07%. The corresponding values of the stills with 5 mm-diameter balls and aluminum foils are 31.41 and 14.87%, respectively. The thermal efficiency of the highest productivity solar still is 27.81%. Other stills are characterized by lower thermal efficiencies by various rates.

A new formula for determining the suspended sediment load in Khour Al-Zubair port has been proposed using dimensional analysis. Six cross-sections have been identified in Khour Al-Zubair port at Basrah province, South of Iraq for the purpose of conducting field measurements during the two tidal periods (Neap and Spring). The study involved taking field measurements of the hydraulic and fluid properties, and sediment sampling by section every 2 h to get effective parameters used for developing empirical formula. These parameters include the density of sediment ( ρ s ), mean velocity ( V ), hydraulic radius ( R h ), fall velocity of the particle ( W s ), median grain size ( d 50 ), the salinity of water ( S ), water level ( W L ), the width of the estuary ( B ), specific gravity ( G s ), maximum flow depth ( D max ), and kinematics viscosity ( ν ). The formula was developed using the statistical analysis using the SPSS program and dimensional analysis method. A good agreement between the loads computed by the suggested formula and the observed data has been attained based on the correlation coefficient value ( R = 0.97). The results showed that the average total suspended sediment loads by using the proposed formula is 1288285.464 tons/year.

The bituminous material performance is affected basically by the prevailing temperatures. The mechanical properties of these materials can vary significantly with the changes in the temperature magnitude. Hot mix asphalt (HMA) is a visco-elastoplastic material, so the pavement structural capacity is affected by the temperature variations. To determine the characteristics of the strength of the flexible pavement rationally, the prediction of the distribution of temperature in HMA pavement layers is a must. Heavy loadings subjected to highways and roads can cause serious deterioration to the HMA pavements. In this research, the temperature for three thicknesses of asphalt pavement structure was measured, and the air temperature to predict a model explains the relationship between the temperature and the depth of the pavement structure. The suggested model was successfully validated utilizing the data from three depths of asphalt pavement structure and the temperature on the surface of the asphalt pavement. The developed model consists of two independent variables, which are the depth within the pavement and ambient air temperature. The predicted model will be useful for the pavement designers those in need to predict the temperature of the profile of pavement to determine the engineering characteristics of field pavement.

This work describes the application of classical Rayleigh method (CRM), modified Rayleigh method (MRM), and ANSYS finite element method (FEM) to calculate the natural frequency of non-homogenous cantilever beam. Two-step cantilever stepped beam was investigated through six studied cases. Each step has different material properties and the same cross section area. Results showed that the combination of materials is useful in order to increase the natural frequencies and reduce the weight of the beam at the same time when the cantilever beam is fixed by the side of the stronger material. There is a good agreement between the CRM and FEM for the region with length larger than half length of beam, on the other hand, there is an excellent agreement between the MRM and FEM for the region with length smaller than half length of beam.

There are several problems facing the construction industry in Iraq. Delays in construction projects affect one of the most important factors in project success, namely time. This delay causes many problems such as increasing the cost of the project, lack of timely operation, and on a larger scale, economic and social impact on the country. As being one of the metropolises of Iraq, the city of Najaf needs a lot of development projects in the development path. Public school construction projects are an example of projects needed in the city, and delays in these projects in recent years have sometimes caused the city’s schools to operate on a mixed basis. This study deals with studies and researches related to the delay of construction projects in other countries, and after interviews and surveys of construction industry stakeholders in Iraq, new factors have been obtained and finally, using the opinions of the mentioned experts, prioritizing the factors extracted from both identified the source and the five main causes of project delays, including late payment to the contractor, design errors, construction length errors, problems with neighbors, and inexperience of contractors. In the next step, the amount of delay due to the main factors identified in the projects was analyzed using the official documents of 30 sample projects from the statistical population of completed school construction projects in Najaf city. Statistics on the amount of delay caused by factors and comparing it with some indicators, the need to use contractors with better ratings, skilled manpower, experienced project managers, and the number of sufficient engineers at the project site were presented.

This study investigates the spatial heterogeneity in the maximum monthly rainfall amounts reported by stations in Ireland from January 2018 to December 2020. The heterogeneity is modeled by the Bayesian normal mixture model with different ranks. The selection of the best model or the degree of heterogeneity is implemented using four criteria which are the modified Akaike information criterion, the modified Bayesian information criterion, the deviance information criterion, and the widely applicable information criterion. The estimation and model selection process is implemented using the Gibbs sampling. The results show that the maximum monthly rainfall amounts are accommodated in two and three components. The goodness of fit for the selected models is checked using the graphical plots including the probability density function and cumulative distribution function. This article also contributes via the spatial determination of return level or rainfall amounts at risk with different return periods using the prediction intervals constructed from the posterior predictive distribution.

The water hammer (WH) phenomenon is one of the most dangerous phenomena in hydraulic systems, especially pipelines, gates, and locks on these lines. There are many analytical solutions to deal with the WH phenomenon, including the treatment of friction losses, but most solutions use linear arithmetic operations, which depart from the actual situation of the WH phenomenon. Also, the methods currently used are most challenging and complex and give imprecise results to treat the mentioned phenomenon. In order to reach a state closer to the situation of losses and stability of the hydraulic system that is close to the actual state, basic partial differential equations were used, taking into account the losses generated in the hydraulic system through mathematical conversion. MATLAB was used to program and solve equations, find mathematical results, draw system diagrams, and simulate a WH wave. Various parameters were investigated to show the stability behavior of the hydraulic system by using state-space Method. So, the effect of the pressure, flow rate, diameter, and fluid type were investigated to calculate the stability of the hydraulic system. The results evaluated showed that the system’s oscillation is less at lower pressure, and the stability period is longer than that at high pressures. In addition, the system needs a longer time to stabilize at the low flow speed due to pressure waves that occur. The stability of the system affected by the WH was examined, and the effect of fluid-specific variables such as velocity, pressure, and type of fluid in addition to the diameter of the pipe and their impact on WH stability was found. The behavior of stability at the WH is nonlinear, and that is why the linear and nonlinear parts of the governing equations of the structure are used to find system through the state-space method through programming and simulation of MATLAB program.

This article discusses the experimental testing of tapered castellated beams (TCBs) under mid-span concentrated load. These beams are created by cutting the webs of standard I-sections in a particular zigzag pattern and rejoining the two parts by placing variable expansion plates between web posts and welding them together. Generally, the depth of the mid-span will be increased. A standard I-section (IPE140) was selected as a parent beam to fabricate three TCB specimens and one prismatic castellated beam. The experimental results showed that the ultimate load capacity of the TCBs could be increased up to 140% of the ultimate load capacity of the parent section. Fabricating a TCB is an effective way of increasing the allowable load of a long-span member while remaining within International Building Code-defined deflection limits. The experimental results showed that the allowable load at deflection (L/360) increased up to 183% of the allowable load for the control specimen at the same deflection. Finally, the experimental results showed that web-post buckling and joint-weld rupture failure modes occurred in TCBs due to the formation of high shear forces that tried to twist the web posts.

In this article, a numerical model based on site theory is developed to study the stability of a pipeline system consisting of a valve, pipe, and surge tank. In the study, four parameters were studied to see how they impact the water hammer phenomenon. They are the pressure in the pipelines, the velocity of the flow, diameter of the conduit carrying liquid, and the liquid’s density. The equations are programmed, analyzed, and graphed using MATLAB. The stability analysis shows that the force of the water hammer is significant at low frequencies and for large diameters. The high frequency of a particular pipe is affected by the type of material the pipe is made from, the method of installation, and the friction coefficient of the inner surface. High frequencies reduce the impact of water hammer forces. Among the main parameters listed, it is found that the oscillations of liquids of low density are higher in the case of water hammers.

This work intends to make structural lightweight aggregate concrete by using artificial expanded clay aggregate with different replacement levels from normal coarse aggregate and improve it with a high-performance superplasticizer to increase its strength. The mechanical characteristics covered in the present work were compressive strength, flexural strength, and splitting tensile strength in addition to freezing and thawing resistance. Different densities were found for all mixes ranging between normal and lightweight concrete and that depends on the replacement of normal aggregate with lightweight aggregates. Mixes with replacement exceeding 25% give compressive strength less than 17 MPa and cannot be regarded as structural lightweight concrete. Modified mixes give higher values of mechanical properties, and also some non-structural lightweight concrete mixes were improved to structural lightweight concrete by using PC-superplasticizer in this study. The research also includes freezing and thawing cycles on reference mixes and lightweight mixes. Lightweight mixes give high durability against freeze-thaw cycles where the reduction in compressive strength was 6.2, 4.6, and 5.5% for 10% rep, 15% rep, and 20% rep mixes, respectively, compared with 32.2% reduction for reference mix.

Volume delay functions (VDFs) are mathematical relationships used by the traffic allocation step of demand forecasting models to take into account the effect of increased traffic flow on the time spent to travel each possible route between different travel sources and destinations. The VDF is usually applied in static traffic assignment to describe the resultant link travel times, as a function of flow and capacity and free-flow travel time. This study aims to investigate the interface between the delay functions used by demand forecasting models and the highway capacity manual (HCM) model flow-speed relationships. The most commonly used VDFs in transport demand modeling packages in the literature were identified. The Bureau of Public Roads (BPR), conical functions (CF), Akçik and Troutbeck function (ATF), and delay logistics function (LF) were described. The four VDFs and the current HCM models were calibrated for the Iraqi road environment, and their compatibilities were examined. Results show that the best adjustments were obtained using the BPR function (quadratic error 0–0.012) and LF (quadratic error 0–0.002). The roles of CF and ATF were used with care, as both appear to neglect the delay in the condition of small to medium traffic patterns typical to country roads. Particularly, in response to single-lane roads, the LF has proven to be useful due to its potential to represent significant delays for low traffic flows and simultaneously produce more delays in congestion conditions; furthermore, the effect of flow as well as intersection spacing is obviously nonlinear. As flow reaches 600 pcu/h/lane, running time increases quickly. With more intersections per kilometer, the impact is obviously greater.

There is a significant challenge to developing the strength and durability of the aerated concrete (AC) for structural applications, but to date, no researchers have focussed on the effect of expanded polystyrene beads (EPS) on the AC properties. EPS-AC consists of cement, sand, water and aluminium powder with commercially available spherical small, hollow and impermeable polystyrene beads. In this research, different contents of EPS from 0 to 4% by cement weight were added to create the AC with different densities. It is revealed that the greatest enhancements in the properties of EPS-AC were noticed when the EPS volume fraction was increased to 4%. The compressive, flexural strength and modulus of rupture were enhanced by 48, 37 and 125% respectively, whereas the density was raised slightly. Moreover, it was shown that all EPS-AC mixes could satisfy the requirements of structural lightweight concrete.

In this research, a hydraulic model is used to find the effect of the cutoff angle and dimensions of the void in the soil on the head pressure and leakage under the dam, and finding the best angle and size of the void will have a positive effect. The model was designed with a cutoff that can be moved in three angles (45°, 90° and 135°) in the center of the dam and three ratios of void dimensions (width of the void ( W )/the dam width ( b ) = 0, 0.34 and 0.69) were taken. Head pressure was measured using a piezometer installed in the front of the model. When the flow reached the balance, leakage and pressure head were measured. From the results, it was observed that the lowest head pressure value occurs when the angle is 90° and the void ratio is 0.69. The principles of dimensional analysis and non-linear regression by using IBM SPSS 19 were used to find an empirical formula for the computation of the head pressure depending on the angle of the cutoff and the size of the void.

The mitigation of vibrations due to a harmonic load induced by a mechanical oscillator is studied experimentally. The vertical components of soil particle velocities are measured (via geophones) at different locations apart from the source, where various frequencies (30–70 Hz) are generated. For normal conditions where no mitigation means are used, it is found that the measured peak particle velocities are proportional to the excitation frequencies. The mitigation effect of constructing an active (near source) open (0.4 m wide × 3 m long × 2 m deep) trench barrier is also studied. The measurements revealed velocity increase at the points in front of the trench due to the reflected waves. This increase is proportional to the vibration frequency. Although the presence of the barrier greatly reduced the peak particle velocities beyond it, it is found that the efficiency of screening is more pronounced at high vibration frequencies. Increased and fluctuated trends of the amplitude reduction ratio are reported away from the barrier. It is realized that passive (near target) screening is less effective for all frequencies except at 30 Hz. Active and passive trenches, filled with native soil–rubber mixture at various ratios (20–40% rubber), are also considered. The rubber material is in a form of tire chips purchased from the Unit of Recycling Scrap Tires in Al-Diwaniyah Tires Factory. Although the in-filled trenches are less effective in screening the vibrations, similar trends and behavior to the open trenches are noted. It is found that the mitigation efficacy is increased with the rubber content.

This article introduced a three-dimension CAD model of a prosthesis testing platform using SolidWorks software to conduct a kinematic and dynamic analysis of the transfemoral prosthesis of the virtual model. Concurrently, the event-based motion simulation (EBMS) procedure was carried out on the CAD model. The concept of the operational strategy of the test platform was clarified through the machine’s real-life experience before being constructed in vitro . The platform model is capable of reproducing two active movements to simulate the locomotion of the thigh angle and hip vertical displacement for assessing the artificial knee angle motion during the gait cycle. These motions were controlled by two rotary forces (motors) that are utilized to implement control actions in EBMS. The prosthetic knee joint was built with a single axis that performs flexion and extension via the axial force of the spring. The simulation results of the thigh angle motion ranged from 2 0 ° 2{0}^{^\circ } to − 1 5 ° -1{5}^{^\circ } , while the maximum flexion of the prosthetic knee joint was ( 4 6 ° 4{6}^{^\circ } ). The mean absolute error was ( 2.72 7 ° 2.72{7}^{^\circ } ) and ( 8.33 8 ° 8.33{8}^{^\circ } ) for the thigh and knee joints, respectively. In conclusion, the findings can be utilized to facilitate the design and development of prostheses.

Resistance spot welding (RSW) is considered as predominant welding technique that is used in the manufacturing of modern automobile structure. The automobile structure is made of high strength steel which is preferred by the car industry companies due to its high strength-weight ratio. This work presents an optimization method for RSW of high-strength low-alloy steel DOCOL 500 LA. Tensile test and microstructure analysis for base material (BM) were carried out to get the mechanical properties of BM and to specify the rolling direction. Taguchi method, high efficiency technique, was applied using Minitab19 software to achieve the optimization process. Tensile shear test was carried out to evaluate the strength of welding nugget, absorbed energy and failure mode. The results showed that the optimum parameters were 8,800 A for the current, 30 cycles for the welding time and 2,230 N for the electrode force and two types of failure modes could be observed which were interfacial and full pullout mode.

Reduced beam section (RBS) behaviours with various cut-flange configurations were investigated numerically in this study. A three-dimensional finite element model material non-linearity was built and validated experimentally, and the impacts of the cut--flange profile on the moment-rotation behaviour and ductility response of moment-resisting connections were investigated in a parametric form. Five-moment connections with various forms of decreasing beam flange were thus modelled using ABAQUS software and compared in terms of cyclic behaviour. RBS with circular, rectangular, trapezoidal, triangular, and drilled holes cut-flange configurations were adopted, and the finite element analysis results showed that radius cut RBS have uniform stress contours, while a re-entrant corner in rectangular, trapezoidal, or triangular cut-flange profiles’ connections may result in stress concentration, resulting in a fracture of the flange. In addition, the numerical testing showed that the RBS connection with a circular cut-flange profile offers a lower rupture index than other connections. Thus, the RBS created using circular cut-flange profiles dissipates more energy than other connections.

In the construction industry, time overrun in construction projects has become a global phenomenon. In Iraq, this problem is very considerable where a high percentage of projects are completed behind schedule, causing a large negative impact on society on the one side and the economic impact on the other side of the country. This study aims to define the major factors that cause construction project’s time overrun by studying delay causes of projects and performing a number of interviews with a group of specialists in project construction. Next, a questionnaire is used to obtain responses from 115 participants in the city of Najaf. In addition, agreement analysis is performed to ensure that the arranged rankings by all involved respondents’ categories are not ordered by coincidence, and the Chi-squared test is put to use as well to mark the agreement or disagreement context among the respondent category rankings. The target respondents of the study included: clients, consultants, project managers, contractors, and engineers who have an experience in project management and construction. The findings of the study revealed that the top five most essential factors causing delay in public construction projects are global and local economic crises, bureaucracy and corruption, public holidays, delay in getting governmental permits, and issuing numerous change orders by owners. Moreover, eight components are extracted from the 45 questionnaire items put to use for factor analysis. Among the extracted factors are the inaccuracy of tendering process, technical performance management, and government interferences.

The aim of this study is to integrate the best lift-to-drag ratio zone to chief the highest power coefficient for horizontal axis wind turbine (HAWT) blade. Different cross-section, symmetrical, unsymmetrical, and supercritical airfoils (NACA 0012, NACA 4412, and Eppler 417) are used. FORTRAN code (f.90) was built to calculate aerodynamic data and the power coefficient based on Blade Element Momentum theory. This article deals selection of the most effective zone from the lift-to-drag ratio versus blade radius curve that gives the best incidence angle distribution. The results show a good performance that leads to approximated equal lift-to-drag distribution along the blade radius that indicates the highest power coefficient of at least 15% increases. The highest values of the power coefficient of NACA 0012, NACA 4412, and Eppler 417 were 0.476, 0.4966, and 0.482, respectively. The lift-to-drag ratio distribution zones were the most specific method of generating the maximum power coefficient for the HAWT blade. Important results and conclusion were found for further blade design.

In this research, the geotechnical properties of the soil profile in Hilla city within Babylon Governorate in the middle parts of Iraq are described. The geotechnical data at the specific sites were collected from some geotechnical investigation reports performed at some selected locations. This article is devoted to studying the distribution of soil properties (the physical and mechanical) in the horizontal and vertical directions. Moreover, a correlation between different physical and mechanical properties is performed. The correlation is executed using statistical analysis by Microsoft Excel Software (2016). From the regression results, it was found that the nature of the soil is cohesive up to 15 m under the natural ground level, and the soil will change to noncohesive. The new line in the plasticity chart has been drawn parallel to A-line especially for the investigated region, the shear strength parameters depend on the consistency of the soil and the depth, and finally, there is a direct correlation between mechanical and physical parameters. Using these correlations with some available information help to predict the value of shear strength and consolidation parameters.

The influence of different concentrations and nanoparticles’ diameter of silicon dioxide nanoparticles on the Nusselt number enhancement ratio and friction factor for solar thermal collector (STC) was examined numerically. The CFD model was designed to show the influence of the flow of water/SiO 2 and pure water inside the pipe on the enhancement of the performance of the STC. Different concentrations of SiO 2 nanoparticles are used ( ϕ = 1–4%) with several nanoparticle diameters (dp = 20–50 nm). The water/SiO 2 and pure water flow under different Reynolds numbers ranging from 5,000 to 30,000. The average Nusselt numbers Nu avg improved by increasing the Reynolds numbers for both fluids. The Nu avg increases with the increase in the concentration of SiO 2 nanoparticles. The water/SiO 2 with nanoparticle concentration of ( ϕ = 5%) and nanoparticle diameter of (dp = 20 nm) has the highest Nusselt number. The Nu avg enhances 25% with water/SiO 2 nanofluid flow at Re = 5,000 and 15% flow at Re = 30,000. It is noted that the skin friction factor decreases with the increase in the Reynolds number for both fluids. Water/SiO 2 nanofluid has a higher skin friction factor than pure water. The Nu avg improved by 31% at the lowest Reynolds number by using water/SiO 2 nanofluid as the working fluid with a change in the concentration of SiO 2 nanoparticles from ( ϕ = 1%) to ( ϕ = 4%) and improved by 42% at the highest Reynolds number of 30,000. The decrease in the nanoparticle diameter led to an increase in the Nusselt number across all Reynolds numbers. The lowest size SiO 2 nanoparticles (dp = 20 nm) provides the highest Nusselt number. The lowest size SiO 2 nanoparticles (dp = 20 nm) provide the highest ratio of enhancement for the Nusselt number in STC. This investigation has confirmed that the flow of water/SiO 2 with AL 2 O 3 nanoparticles of 5% (diameter of 20 nm) has a significant influence on heat transfer enhancement to improve the thermal efficiency of STC.

Greenhouse is one of the most recent agricultural systems that provides an economic resource by increasing production and allowing crops to be grown all year. In Iraq, this approach encounters an impediment during the summer. As a result of the rapid rise in temperatures, greenhouses are becoming increasingly ineffective. In this season, it is unusable. A two-stage evaporative cooling system was used in this study, with one indirect evaporative cooling heat exchanger and three direct evaporative cooling pads. The performance of the proposed indirect–direct evaporative cooling (IDEC) unit with various settings was tested during the summer season in Kirkuk, with dry bulb temperatures ranging from 45 to 50°C. The results reveal that using groundwater increased the IDEC unit’s efficiency to 98.3%, compared to 67.5% when using direct evaporative cooling. When covering layers were used, solar intensity entering the greenhouse was lowered from 11.4% for a single layer to 28.4% for two layers with one layer of green mesh. In comparison to ambient circumstances and according to the parameters analyzed, the IDEC system employing groundwater results in a decrease in greenhouse temperature and an increase in greenhouse relative humidity. The IDEC unit was verified using TRANSYS software and experimental measurements from a test greenhouse. For the same ambient temperature, simulated and experimental findings revealed that the simulated temperature is lower than the experimental temperature. The percentage difference in greenhouse temperature between the TRANSYS simulation and experimental measurements reached a maximum of 9.43%.

Polyolefin fiber is a new type of fiber that was used in concrete to improve some of the poor properties of concrete including; tensile strength, ductility, and fracture energy. In this research, the contribution of Polyolefin fiber in improving the properties of hardened concrete was examined by adding polyolefin fibers to mix with different fiber content. The polypropylene fibers were added as a ratio of 0.5, 0.75, 1.0, 1.5, and 2% of concrete volume. Destructive and non-destructive tests were carried out: slump, compression, splitting, and bending, Schmidt Hammer, and ultrasonic pulse velocity tests. The results showed that, as the polyolefin fiber content increases, the workability of concrete reduces dramatically. The experimental findings demonstrate that the concrete tensile strength and ductility were improved by a small improvement in overall compressive strength. The results show that the compressive strength increased gradually with the increase in fiber content of up to 1.5%, and then, the compressive strength starts to decrease. However, the tensile strength increases continuously with the fiber content increasing. A good relationship was obtained between the destructive and nondestructive tests.

Soil functions such as water storage, soil filtration, and reducing reservoir life due to sediment load are directly affected by the process of “soil erosion.” The Universal Soil Loss Equation was adopted to predict the erodibility factor for watersheds feeding the Al-Shewicha trough. The K -average factor’s determined value was 0.156, indicating that the K -factor had substantial variability. The K -factor for erodibility values was linked to the high sand content in the topsoil of the study area because of the high sand content of the topsoil. The topsoil is coarse-textured and then permeable. ArcGIS (geographic information system) was used to obtain the distribution of soil types as well as the erodibility factor distribution.

Researchers have been focused on evaluating topographic maps in order to identify property and infrastructure and address issues relating to property disputes and its ramifications for a given country. However, over time, the requirements for map production have changed and evolved, and there is a need for an increased level of quality and standard in the map making process. Several cities in Iraq, including Baghdad (capital), do not comply with the existing standards set by the Department of Survey Mapping in Iraq (DSMI). One of the main concerns and issues is with the quality of mapping which is mainly due to inaccurate digitizing procedures. Therefore, the aim of this study is to produce seamless topographic maps using vector data to overcome the problem of no-overlapping that often occurs in producing maps. However, there is another issue regarding edge matching and the lack of standards being met according to the MS1759 procedure. To address this issue, ArcGIS 10.3 software is used as a tool to process data, analyze the index maps, and to produce seamless geospatial data using seamless methods. The database is set up using the characteristics and code properties from the MS1759 standard. The orthophoto image is used as the base map in which the series of maps used is MY Series and its area is of Baghdad. The results indicated that seamless topology is far easier to handle than the base cartography. It also demonstrated that using this method aids in analyzing the data in a far more detailed manner than existing techniques. Overall, the study concludes that seamless topographic map has a better GIS ready quality and the produced map is far more qualitative than the existing map of the Baghdad.

This article investigates the novel mechanical behavior of metal–metal gradients (Al/Zn) of the functionally graded materials (FGM) type. The experimental work includes the manufacture of three different models (FGM 1, FGM 2, and FGM 3) with various proportions of volume fraction and gradation as (100% Al–50% Al–50% Zn–50% Zn–50% Al–100% Zn), (100% Al–30% Zn–70% Al–70% Zn–30% Al–100% Zn) and (100% Al–70% Zn–30% Al–30% Zn–70% Al–100% Zn), respectively. The annealing process was carried out to eliminate the casting problems of the FGM. Mechanical tests such as tensile and hardness were performed using different parameters of the gradient of properties for each model. Hardness tests for each model were carried out by the circumferential method along the rod made of the FGM and in the radial direction from the core of the models and at different distances. In the third model, the modulus of elasticity and ultimate strength were 79 and 377 MPa, respectively. The densities of the three models were measured experimentally and theoretically. The results show that model FGM 3 has a tensile strength of 6, which is 10% more than that of models FGM 1 and FGM 2. The results showed a significant improvement of 22% in the tensile strength on average compared to the aluminum–zinc alloy. The circumferential method of hardness testing gives variant results than the radial type due to the properties of FGMs.

In construction projects, the nature of the construction process is complicated, and many factors and variables have a significant role at any stage of the project. Thus, when change orders (COs) occur, the project’s function is strongly affected. This study aims at identifying and evaluating the causes of COs in Al-Najaf province projects based on project cycle (stages), to initiate proactive measures to reduce changes during the construction process. This research reviews the previous literature to identify factors causing the COs to develop a categorized questionnaire based on project cycle/stages. Data were collected through field surveys by completing 45 questionnaires during the Autumn of 2018. Analysis results indicated that the COs in construction sites were the result of 24.10% planning, 24.70% design, 11.30% bidding, 36.20% implementation, and 3.70% handover. However, top-ranking causative factors show that the unavailability of project materials in the market is 2.60%, the economic situation of the country and the lack of financial returns is 2.55%, owner capacity in cost estimation is 2.35%, obstruction and delay in giving responses and approvals is 2.30%, indirect cost is 2.29%, and the contractor’s experience or technical competence which is not compatible with the project is 2.29%. The top-ranking factors which belonged to the design stage were implementation, planning, design, and bidding stages. The results revealed that the validity of the proposed methodology compared to previous studies and recommendations for further studies was indicated. These outcomes can assist the construction engineers and contractors to enhance the effective change management process and could initiate further research in this field.

An aqueducts are a water source (the channel that a flowing body of water follows) designed to transport water from a specified point to a point where the designer aims to distribute the water within it. To enhance the hydraulic properties of pipe aqueducts, a workable, efficacious, and convenient method for the optimal design of an aqueduct has been determined in this research article to study the optimum design of pipe aqueduct (finding optimum diameter) and study the effect of design parameters on safe span length by MATLAB Software R2017b and Newton–Raphson method and check the effects of the parameters of design such as the span length ( L ), discharge ( Q ), overhead loss ( H ), inlet and outlet coefficient ( K K 1 & K K 2), etc. Also, this article studies the safe span ( L ) depending on the optimum value of pipe diameter.

This work presents finite element (FE) modeling using the ABAQUS program to investigate the effect of steel reinforcement with three different types of high-strength steels, grades 420, A1035, and SD685 on the flexural behavior of RC beams under monotonic loading. Experimental findings from the literature have been used to validate the proposed model. The numerical load, deflection, mode of failure, failure concrete strain, and bottom steel strain at failure of 24 numerical specimens with collapsed conditions of tension-controlled, balanced, and compression-controlled are recorded. Also, the effect of compression reinforcement is being investigated. The results reveal that the flexural behavior of the experimental test for the three steel grades is well validated by FE analysis. The ductile and brittle behavior features of yield strength (YS) larger than 420 can be predicted for specimens designed according to current standards ACI-318M-19. Also, the compression reinforcement improves load capacity while reducing displacement. It may be argued that when YS decreases, tensile stress and strain of flexural rebar rise, causing the beam to become more ductile. When the YS increased, the brittle behavior was induced.

The intensity of rainfall can be considered as an essential factor in designing and operating hydraulic structures. The intensity–duration–frequency (IDF) curve is used for designing hydraulic projects such as drainage networks, road culverts, bridges, and many other hydraulic structures. In the field of water resources engineering, IDF curve is dependent widely on the plan, designing, and operating the project. Additionally, it can be used for different flood engineering structures. The purpose of this research is to get the frequency of the intensity of rain duration for Al KUTcity, Iraq, and find curves. Three essential techniques of frequency analysis (Gumbel distribution, lognormal, and log Pearson Type III) were depended to formulate this relationship based on data of rainfall intensity during the period between 1992 and 2019. Distribution methods involving lognormal, Gumbel, and log Pearson Type III were applied by Indian Meteorological Department (IMD) for short periods of 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 12, and 24 h with 2, 5, 10, 25, 50, and 100 years return periods. The results showed that rainfall intensity reduced as the duration of the storm increased, and if the return period of the rainfall was large, rainfall of any specific duration showed a higher intensity. Using EasyFit 5.5 software, for all durations, the lognormal probability distribution showed the best fit for the data group and estimated intensities of precipitation for return periods of 2, 5, 10, 25, 50, and 100 years. According to the obtained results, one can notice that the intensity of rainfall increased with the increment in return periods, but decreased with the increment in duration. The resulting IDF models could be used to improve accuracy and results.

Quantum-dot cellular automata (QCA) technology was proposed as a way to implement digital circuits with a transistorless approach for overcoming CMOS limitations in terms of short channel effects and scale-down continuity. The main building block in QCA technology is the square cell with a couple of free movement electrons, the electrons’ configuration inside the cell gives the cell the ability to represent binary information. Researchers were attracted to QCA because of its impressive features such as size and speed. Many important circuits, such as multiplexers and exclusive-OR, were presented in QCA technology with various layouts, looking for reducing the main metrics such as cell count, area, and implementation cost. In this work, a dual functional XOR block is proposed. The proposed block can function as a 2-input XOR or a 3-input XOR, providing greater flexibility. When compared to earlier 3-input XOR gates that did not have the dual function, the results show a significant improvement in cell count, area, and cost of about 7%, 50%, and 54%, respectively. The QCADesigner software is used to design the block as well as for verification issues.

The disposal of the waste material is the main goal of this investigation by transformation to high-fineness powder and producing self-consolidation concrete (SCC) with less cost and more eco-friendly by reducing the cement weight, taking into consideration the fresh and strength properties. The reference mix design was prepared by adopting the European guide. Five waste materials (clay brick, ceramic, granite tiles, marble tiles, and thermostone blocks) were converted to high-fine particle size distribution and then used as 5, 10, and 15% weight replacements of cement. The improvement in strength properties is more significant when using clay bricks compared to other activated waste ceramics and granite tiles. The percentage increases to 11.59% at 28 days for compressive strength when using 10% replacement of cement weight. The ability to produce eco-SCC with less cement content and lower cost consumption is encouraged, although the enhancement in strength is not high since the waste can be disposable. While the percentage reduction in the strength of SCC mixes containing marble tile or thermostone block powder increases with the replacement of cement weight with a greater need for superplasticizer justification, we recommend using 5% as a replacement by weight of cement with an insignificant retardation of strength. Finally, there is a good relationship between compressive strength and ultrasonic pulse velocity and between tensile and flexural strength with a high R 2 .

The purpose of this work is to evaluate the performance of the anaerobic baffled reactor (ABR) for on-site primary treatment of domestic wastewater in rural areas of Iraq. The performance of the three-chamber ABR has been investigated at four different hydraulic retention times (HRTs) ranging from 6 to 36 h. The results showed that the chemical oxygen demand (COD) removal efficiency is enhanced with increasing HRT, where it was recorded at 75, 71, 63, and 56% removals rate of COD at HRTs of 36, 24, 12, and 6 h, respectively. The mean steady-state removals of total suspended solids are 91, 78, 72, and 67% at HRTs of 36, 24, 12, and 6 h, respectively. Also, it was shown that there was low-nutrients removal within the ABR. Consequently, the effluent ABR wastewater needs to be post-treated before being discharged to the receiving water bodies. In general, it is concluded that the ABR could introduce a solution for on-site primary treatment of domestic wastewater in rural communities in Iraq.

Currently, there is a rapid increase in demand for the transmission of large amount of data with extreme accuracy, which is usually performed by the antenna system. Therefore, this work aims to design an antenna system that has the potential of improving the performance of such system in terms of reducing the antenna size, and expanding the bandwidth. First, a single-port antenna was designed after calculating the basic requirements and then a comprehensive analysis of the antenna performance was carried out to reach optimum performance. Then, the antenna was connected to two, three, and four ports. Such connection was implemented while maintaining efficiency and magnification in each case within the range for wireless applications. The antenna with four input ports was designed with a 45° angle on a circular circumference around the antenna to prevent interference between the ports. The modified antenna was designed to accommodate wireless communication applications (such as the 5G mobile communications network as well as the future 6G mobile communications network). The experimental results were compared with those obtained from the simulation studio Computer Simulation Technology, which is more compatible with the practical results.

Turbidity is one of the major problems in the treatment of drinking water. Turbid water contains molecules, plankton, and colloids, and is dealt with through the addition of coagulation chemicals in processes called coagulation and flocculation. In this research, three of the most commonly used coagulants utilized in the process of turbid water treatment are examined for their efficiency in reducing turbidity. The three types of different coagulants that have been employed are aluminum sulfate (alum), ferric chloride, and poly aluminum chloride (PACl). The samples are taken from the Tigris River at various levels from the water’s surface (60, 120, 180, 240, and 300 cm). The results showed that PACl is more efficient in removing turbidity than alum and ferric chloride. Ferric chloride is a more efficient coagulant than alum at different ranges of turbid water. In this study, the effects of employing a natural coagulant such as “Walnut coat” with PACl and synthetic polyacrylamide with PACl for removing turbidity are compared to using PACl alone. When compared to PACl alone, polyacrylamide with PACl was effective in removing turbidities of 22.8 and 25.7 NTU. Walnut coat was also proven to be more effective when combined with PACl for lower turbidities (20.7 and 21 NTU). Within the first 5 min of slow mixing with polyacrylamide, large, transparent, and readily settled flocs formed, whereas the same flocs formed after 30 min of slow mixing with PACl and walnut coat as flocculant. With both polyacrylamide and walnut coat as coagulants, better sludge properties were obtained, with low water content and high density that can be readily dried and disposed of.

This article presents test results documentation for four grouted ground anchors embedded in sandy soil. Three anchors were trial, while one was a working anchor. One trial anchor is instrumented with eight resistance-type strain gauges glued on the corrugated pipe and embedded within the grouted body. An acceptance test was made for all anchors to determine the working load. Acceptance criteria suggested by the Post-Tensioning Institute were applied, and the working anchor did not pass the creep criterion, so it was taken out of service. The strain measurements indicated that the compression stresses were generated along the free length, while the tension stresses were generated along the bonded length. The transition point, which is the point with zero axial stress within the grouted body, was located at a distance of 10–12% of the bonded length, measured from the proximal end of the bonded length. The skin friction distribution along the grouted body was nonuniform, and it had a peak at the transition point. The maximum measured value of the skin friction is almost compatible with the estimated one by Fujita’s formula. The skin friction developed along the free length indicates a significant contribution of the free length to the pullout capacity.

One of most important things now is to create smart street and smart lighting system to save enormous electrical energy. Especially Iraq is suffering shortage of electrical energy generation up to 45%. Because of this, Iraq needs to save a lot of electrical energy in the entire country so as to meet the electrical demand and reduce the large amount of CO 2 emission. However, this work presents a very unique and economic control lighting system (CLS) for main streets and sidewalks, which can control the lighting system to give sufficient illumination to the drivers and the pedestrians simultaneously. And at the same time, the CLS system can reduce a lot of electrical energy consumption and the CO 2 emissions together. However, by using these smart systems with the exciting illumination source in the streets, the CLS can minimize the electrical energy consumed for the lighting at the main roads and the footpath by about 60% and can use the surplus energies to fill the shortage of electricity in the country. Also, this system will increase the lifetime of the lighting system which means further decrease in cost. Finally, this work presents new type of illumination source, high-intensity discharge (HID), which can reduce the electrical consumption much more by up to 90%, when using the CLS with HID.

The impacts of different replacement levels of micro silica (MS), fly ash (FA), and the combined usage of MS and FA on the behavior of concrete were investigated. Design of experts has been used incorporating the response surface methodology to find the synergetic effect of FA and MS on fresh and hardened concrete properties. A total of 15 and 30% of the binder content were replaced by FA. As well as a total of 5 and 10% of the binder content were replaced by MS. Experimental results of concrete mixtures have been used to construct ANOVA models. These models have also been confirmed to expect the properties of concrete mixtures based on different fractions of FA ash and MS. All statistical models are significant because P -value is less than 5%, and the difference between predicted R 2 and adjusted R 2 is lower than 20%. The variation between confirmation tests for the optimized mixture and test results are lower than 5%.

The ergodic capacity of the ideal multiple-input and multiple-output (MIMO) channel grows unboundedly at the-high SNRs because of the assumption that the transceivers used in the system do not affect the signal that passes through them. In reality, the transceivers used in the MIMO system suffer from many impairments such as phase noise, quantization noise, and non-linear amplifier. These physical transceivers will affect the signal that passes through them. Thus, the influence of the physical transceivers cannot be neglected in the analysis of the MIMO channel capacity. Additionally, another essential thing that must be considered when analyzing the MIMO channel capacity is the correlation between the channel elements. Therefore, to get results close to the behavior of the practical results for the capacity of any MIMO system, this article proposes an algorithm that simulates the capacity of the correlated MIMO channel that suffers from Rayleigh flat fading with the presence of the physical transmitter. This work is done by considering that the effect of the physical transmitter at the n th transmitting antenna is a Gaussian distortion noise with a zero mean and variance proportional to the power of the signal transmitted through the same antenna. The simulation process for the proposed technique is manipulated by MATLAB software with 10,000 realizations of the channel. Also, the transmitter impairment thresholds employ in the simulation are 0.08 and 0.175. The simulation results showed that the channel capacity with the physical transmitter stopped growing at a specific limit in the very high-SNRs, and it decreased at the medium and high SNRs when the correlation coefficient increased.

Conjugate heat transfer is a complex problem because heat is transferred from a solid medium to a liquid medium through their interfaces. The steady-state laminar flow formed inside the microtubules is subjected to a constant temperature at the outer sidewall surface. These images cover a wide range of wall-to-fluid thermal conductivity ratios (ksf = 1, 2, 3, 4, and 5) and wall thickness-to-inner diameter ratios ( δ /Ri = 0.25, 0.5, 0.75, 1, 1.25, and 1.5) and Reynolds numbers (Re = 200, 400, 600, 800, and 1,000). The results are processed by a Fluent program based on the finite volume method to numerically integrate the driver’s differential equations. The results show that increasing the wall-to-fluid thermal conductivity ratio ksf increases the inner wall dimensionless temperature and decreases the average Nusselt number. Conversely, an increase in the ratio of wall thickness to inner diameter results in a decrease in the dimensionless temperature of the inner wall and an increase in the average Nusselt number.

Global energy consumption is increasing due to population growth and with it the adverse impact of fossil fuels on the environment, making it necessary to use renewable energy sources and convert them to electrical energy using different technologies. However, the solar energy potential remains unused, while it has numerous advantages, including as a source of clean electricity and heat. One of the main difficulties in energy-saving and compacted design is how to increase the heat transfer of solar equipment. As an innovative approach to enhancing fluids’ heat transfer performance, some of the most active techniques are to exchange the working fluid with nanofluids. This work attempted to demonstrate heat transfer behavior changes when using nickel oxide (NiO), aluminum oxide (Al 2 O 3 ), and copper oxide (CuO) as nanofluids at concentration volumes of 0.05, 0.075, and 0.1%. For this goal, a conical solar collector was built using local public steel sheets. Insulating polyurethane foam padding is used inside the cone. The sun’s energy is focused on the absorbing surface using thin reflective aluminum foil. The study also includes a literature review showing how nanofluids can improve heat transfer in solar collectors. The results showed that adding nanoparticles can increase the rate of heat transfer and CuO nanofluids have better augmentation in heat transfer than Al 2 O 3 or NiO-water nanofluids where 1% CuO nanofluids increases the efficiency by up to 7% compared to water.

Designing mixtures of asphalt with a porous structure to gain good trainability decreases both the propagation and generation of traffic noise. Porous asphalt (PA) mixtures use crushed stone, a small proportion of processing sand, admixtures, and asphalt binders. Therefore, this study aims to examine the impact of adding crumbed rubber into the mix of PA. However, the optimum amount of the binder used in the reference mixture without crumb rubber (CR) and the mixture with 10, 15, and 20% of crumbed rubber waste was identified by utilizing drain down. The test of Cantabro loss, air voids, and indirect tests of tensile and permeability were performed on samples to identify the influence of adding crumbed rubber on the features of the PA mixes. The optimum asphalt content achieved is 6.3%. The results indicated that CR decreases PA permeability, while the additional amount of crumbed rubber in PA negatively influences PA characteristics.

Scholars have spent much time studying metal deposition procedures involving the deposition of electroless nickel, alloy, and composite coatings on various surfaces; the most current uses were feasible advantages of the coatings’ many good properties for achieving the final product innovation. Lately, these coatings have demonstrated intriguing wear and corrosion resistance features, resulting in several innovative macro-level developments. The notion of composite coating by co-deposition coating has been presented in this article. The characteristics of Ni–Pb alloy coatings were examined by inserting ZrO 2 {{\rm{ZrO}}}_{2} particles into the electroless deposited solution. The stainless steel (SS) specimens have been electroless coated with Ni–Pb and ZrO 2 {{\rm{ZrO}}}_{2} nanoparticles (size = 30–70 nm) at 0, 10, and 20 g/L amounts. The materials have been examined using scanning electron microscope and atomic force microscope, followed by wear-resistant and microhardness testing. According to the investigation findings, including inert particles improved the hardness magnitude and wearing resistance considerably. The base metal exhibited the highest wear rate at 10 N, while the wear rate decreased in the Ni–Pb– ZrO 2 {{\rm{ZrO}}}_{2} -coated SS316L by 34%. The Vickers hardness magnitudes of the Ni–Pb– ZrO 2 {{\rm{ZrO}}}_{2} -coated samples at different ZrO 2 {{\rm{ZrO}}}_{2} contents (0, 10, and 20 g/L) were 19, 50, and 81%, respectively.

Concrete is the most popular construction material and has a relatively high compressive strength and it does not crack under its own weight, but its tensile strength is much lower compared to its compressive strength. The compressive strength can be changed according to the water to cement ratio during concrete formation or mixing, while the tensile strength rises when additives are used, concrete needs reinforcing steel, and added to plain concrete, resulting in reinforced concrete. In other terms, concrete consists of sand or fine aggregate, gravel (which is a coarse aggregate), water, and cement (which is considered a bonding material), and it is a brittle material that needs reinforcement and also some admixtures to improve its low tensile resist. This research aims to increase and improve some mechanical properties of concrete by using waste tiles as coarse aggregate. The study includes replacing normal aggregates with waste tile and using them as crushed aggregate with 25, 50, 75, and 100% replacement. Studies show increment in compressive and tensile strength and flexural strength by using waste tile aggregate compared with ordinary concrete; compressive strength increased from 34.1 MPa for reference mixes without waste tiles to 39.8 MPa using waste tiles. The study included improving all mixes with polycarboxylate superplasticizer and gaining high strength concrete, especially mixes with 50, 75, and 100% waste tile aggregate; the compressive strength with totally waste tile replacement gave the highest value of compressive strength, which was 57.5 MPa, tensile and flexural strength also increased by using waste tile aggregate, and 100% replacement shows optimum values of mechanical properties in this study.

The present study considered an impingement jet using hybrid nanofluid CuO–Cu/water. A single rounded nozzle was used to impinge a turbulent coolant (water) on the hot circular plate at Reynold’s number range of (5,000–15,000). CuO–Cu nanoparticles were physically synthesized at 50 nm size and dispersed by one-step preparation method. The experimentations were conducted with nanoparticle concentrations range of (0.2–1%) by volume. The results showed that the presence of hybrid nanoparticles exhibits a significant improvement in the overall thermal performance of the working fluid. Where the gained heat interpreted by the Nusselt number was found to be 2.8% (in comparing with deionized water) at ϕ = 1% and Re = 15,000, while the minimum gain in the heat was found to be 0.93% at ϕ = 0.2% and Re = 5,000. Furthermore, it was noted that the excessive increase in CuO–Cu nanoparticle concentration causes more pumping power consumption. Moreover, the CuO–Cu nanoparticles residual layer was found to be formed at a high CuO–Cu concentration, which acts as an insulation layer that hinders the heat exchange. It was also found that the threshold of nozzle-to-plate spacing is H = 4, before which, the heat gain is positive, and negative plummet after.

Over space optical communications are considered as the critical technology for high-bandwidth, high-speed, and large-capacity communications. Indeed, the laser wavelength’s narrow beam divergence requires a precise beam pointing at both ends of the optical link. The precise beam pointing makes the laser beam pointing to or from a moving object is one of the most challenging processes for optical space communications. In this work, the effect of the pointing error due to satellite platform vibration over the performance of the laser communication link of the optical inter satellite network (OISN) system in terms of the quality factor is investigated. Indeed, an optical communication system has been built using the OptiSystem program to simulate the link between satellites in space for the OISN system. In addition, the proposed system shows by simulation the optimal parameters’ values required for the design of the optical communication link between satellites of the OISN system. Moreover, the effect of pointing error due to the platform vibration on the performance of the OISN system is investigated for different scenarios of the pointing error (i.e., no pointing error; one side of the link with pointing error, and two sides of the link with pointing error). The simulation shows that, first, the optimal parameters that can be used for the optical communication link between satellites of the OISN system in terms of the laser wavelength; laser power; optical modulation scheme; optical telescope aperture diameter; and telescope optical efficiency. In addition, the simulation shows that existing pointing error due to vibration at one side of the optical link leads to degradation of the performance of the OISN system in terms of the quality factor for different laser beam power; distances between satellites; telescope diameters; and telescope efficiencies. Moreover, existing pointing errors at the two sides of the optical link lead to rapid degradation of the considered OISN system performance even with the increase of the laser power or telescope diameter, which tend to compensate for its effect initially and then quit.

The use of recycled polymers in natural fiber-based composites provides an additional competitive advantage with their environmentally friendly properties. This study utilizes recycled high-density polyethylene (r-HDPE) as a composite matrix with bamboo fiber reinforcement that has been treated with an alkaline process. This study aims to analyze the mechanical properties and thermal properties of r-HDPE composites manufactured by extrusion molding with different bamboo fiber loadings. The specimens were subjected to tensile and impact testing for evaluating the mechanical properties. Thermogravimetric analysis (TGA) was performed to identify thermal stability, while the differential scanning calorimeter (DSC) was used to analyze the melting point phase of each specimen. This study indicated that the tensile strength of the composites decreases with increase of fiber fraction. The composite with 0% bamboo fiber showed the highest tensile strength of 8.3 N/mm 2 , while the lowest tensile strength is shown by the composite with 30% of bamboo fiber. Scanning electron microscopy showed porosity, pull-out, fiber cracking as the indicators for the material failure during tensile testing. From the impact test, it can be shown that the composite with 10% bamboo fiber records the highest impact strength at 37.7 J/m 2 . The TGA indicated high thermal stability of r-HDPE composites with 10% of bamboo fiber at 362.4°C temperature. A similar result was also exhibited from the DSC test, where the material with 10% fiber loading shows a big change in melting phase temperature. This research evidences the effect of bamboo fiber in increasing the impact strength and thermal stability of recycled HDPE matrix. This material could be the alternative for light-bearing applications such as automotive indoor components.

Batteries are a very efficient energy source used in an all-digital environment that adapts to today’s human mobility. The lithium-ion battery is one of the batteries used in various household appliances. There are some problems caused by the anode in terms of utility. This is due to high electrochemical reactivity, which can reduce battery performance. One of the innovations in lithium-ion batteries is anode-free Li-ion battery (AFLB). The working mechanism of this battery is the same as the previous Li-ion battery, but with a smaller anode capacity, so that it can reduce the volume (large) of the battery. The problem that arises is the growth of dendrites that interferes with the battery’s running mechanism, so it needs to be evaluated for its growth. The way that can be done is to modify the copper foil by adding Cu. The innovation of this research is to modify Cu-foil by adding Cu from cable waste. The research method used is leaching Cu from cable waste, followed by reducing Cu powder to form a modified Cu. This study’s data collection techniques include empirical research derived from previous studies and instrumental analysis using SEM, FTIR, and electrochemical performance tests. Electrochemical testing using a cylindrical battery with a current of 1 C (1 C = 430 mA g −1 ) and a voltage of 2.6–4.3 V obtained ALFB and ALFB Cu-modification batteries with a discharge capacity of 70 and 123 mA h g −1 , respectively.

The high sulfide ion polarization is known to cause increased ionic conductivity in the solid sulfide-type electrolytes. Three groups of sulfide-based solid-state electrolytes, namely, Li-P-S, Li 6 PS 5 X (X: Cl, Br, and I), and Li x MP x S x (M: Sn, Si, and Al) were reviewed systematically from several aspects, such as conductivity, stability, and crystal structure. The advantages and disadvantages of each electrolyte were briefly considered and compared. The method of the preparation was presented with experimental and theoretical studies. The analysis that has been carried out showed that the solid electrolyte Li 10 GeP 2 S 12 is superior to others with an ionic conductivity of 12 × 10 −2  S cm −1 . This conductivity is comparable to that of conventional liquid electrolytes. However, the availability and high price of Ge are the problems encountered. Furthermore, because sulfide-based solid electrolytes have low chemical stability in ambient humidity, their handling is restricted to inert gas environments. When solid sulfide electrolytes are hydrolyzed, structural changes occur and H 2 S gas is produced. The review’s objective includes presenting a complete knowledge of sulfide-solid electrolyte synthesis method, characteristics, such as conductivity, structure, and stability, as well as generating more efficient and targeted research in enhancing the performance of the chemical substance.

Gel polymer electrolyte (GPE) membranes of polyvinylidene fluoride-based polymer matrix of different filler types such as nano-clay, ZnO, and SiO 2 extracted from fly ash is produced using the non-solvent induced phase separation method. Moreover, the electrochemical properties, electrode compatibility, and the batteries performance are investigated using these gel electrolyte membranes. It is observed that gel electrolytes with nano-clay filler exhibited more stable ionic conductivity and charge–discharge performance than those containing ZnO and SiO 2 extracted from fly ash. A maximum ionic conductivity of 5.62 × 10 –3  S cm −1 was obtained with the addition of 8 wt% nano-clay filler at room temperature. The LiFePO 4 performance assembled with these membranes is examined using coin cells (LiFePO 4 /GPE/graphite). After 50 cycles with a rate of 0.2 C, the battery with a different filler retained 97.7% of its initial capacity. It should be noted that this type of filler influences the electrolyte absorption, electrochemical properties, and performance of the LiFePO 4 .

Bismuth ferrite (BiFeO 3 ) is an interesting multiferroic material due to its ferroelectric properties at room temperature. In this study, Bi 1− x Pr x FeO 3 and BiFeO 3 films were grown on quartz substrates by the chemical solution deposition method at 600 o C of annealing temperature. Variation in molar concentration in Bi 1− x Pr x FeO 3 was set ( x = 0.03, 0.05, 0.1, and 0.2) to investigate their crystal structure and optical characteristics. BiFeO 3 and Bi 1− x Pr x FeO 3 films were examined using X-ray diffraction (XRD) and ultraviolet (UV)-vis spectrophotometer. The XRD results demonstrated that the addition of Pr in BiFeO 3 shifted the diffraction angle to smaller angles so that it reduced their lattice constant. Besides, the crystal size declined with more Pr numbers, while the lattice strain expanded. The UV-vis characteristics of the films were measured in the wavelength range of 200–800 nm. The transmittance values of the Pr-doped BiFeO 3 increased. Because of Pr doping, the refractive index of the Bi 1− x Pr x FeO 3 films decreased while the energy dispersion increased.

The increasing use of lithium-ion batteries (LIBs) presents a serious environmental problem. These spent LIBs are suitable sources of metals for the production of LIB cathode active material. This study successfully recovered nickel, cobalt, and aluminum from spent LIB nickel cobalt aluminum oxide (NCA) and regenerated NCA cathode. The effect of the spent anode as a reducing agent was also investigated. The spent anode alone did not reduce the metals Ni and Co sufficiently. The leaching efficiency was only 34.8, 47.15, and 86.75% for Ni, Co, and Al, respectively, and these values did not increase with increasing citric acid concentration or the addition of ascorbic acid as a reducing agent. However, it increased significantly to 85, 90.12, and 100%, for Ni, Co, and Al, respectively, with the addition of 2% v/v H 2 O 2 . The ternary metal oxalate (TMO) precipitation of the leaching solution confirmed the synthesis of TMO from the precursor. The regenerated NCA synthesized from TMO had better electrochemical performances than those of new commercial NCA. It had a specific discharge capacity of 137 mA h/g and a retention capacity of 85.4% at 2 C after 50 cycles, whereas the new commercial had a specific discharge capacity of 133.4 mA h/g and a retention capacity of 82.6% at 1 C after 50 cycles.

Li-ion secondary battery is highly recommended as a power source to highly advanced battery electric vehicles. Among various types, the lithium nickel cobalt aluminum oxide (NCA) battery is considered suitable for high energy and power application. In this study, the NCA cathode material LiNi 0.89 Co 0.08 Al 0.03 O 2 was produced via the oxalate co-precipitation technique to reduce the overall production cost and process complexity. Oxalic acid and a small amount of sodium hydroxide were used as the precipitant and pH regulator, respectively. Homogenous and loose metal oxalate precipitate formation was confirmed by X-ray diffraction (XRD), scanning electron microscopy, and Fourier-transform infrared spectroscopy analysis. XRD patterns of the as-obtained micron-sized NCA showed a well-layered hexagonal structure. The electrochemical properties of the cathode in the full cell were thoroughly examined. The specific discharge capacity of the as-obtained NCA in NCA/LiPF 6 /graphite at a current rate of 20 mA/g was 142 mAh/g. The as-prepared NCA sample had capacity retention of 80% after being charged and discharged at 0.1 A/g for 101 cycles. Scaling up of NCA production process to 2 kg per batch was conducted and evaluation of NCA product quality was performed by material characterization. Based on the overall results and considering the overall process, such an approach is expected to be developed and improved for future large-scale production purposes.

The corrosion polarization behavior of 439ll ferritic (439ll), 316L austenitic (316L), and NO7208 nickel-chromium-aluminum-iron (NO7208) stainless steels, and Ti6Al4V titanium (Ti6Al4V) alloys was studied in 4 M H 2 SO 4 + 5% NaCl solution at 35 and 70°C. Corrosion rate ( C R ) of the alloys were generally higher at 70°C. NO7208 and 439ll alloy exhibited higher resistance to general corrosion at 35°C (0.067 and 0.050 mm/year) while Ti6Al4V was the most reactive (0.506 mm/year). Passivation behavior was evident on the plots of NO7208 and Ti6Al4V alloys. NO7208 pitted at 1.04 V with passivation range of 0.17 V. Metastable pitting occurred at 0.02 V and ceased at 0.19 V. Pitting was absent from the polarization plot of Ti6Al4V though it exhibited metastable pitting at −0.39 V and passivated at −0.21 V. At 70°C, NO7208 alloy exhibited the lowest C R (0.392 mm/year), while Ti6Al4V was the most reactive at 21.868 mm/year. C R of the alloys increased by 97.63%, 91.18%, 82.83%, and 97.69% at 70°C. Corrosion potential of the alloys shifted cathodically at 35 and 70°C signifying dominant cathodic processes. Ti6Al4V exhibited passivation behavior at 70°C with no pitting evidence. Open circuit potential measurement showed that Ti6Al4V was the most electronegative and NO7208 alloy was the most electropositive due to the significant growth of its protective oxide. Grain boundary corrosion was visible on 439ll and 316L at 35°C and total surface deterioration at 70°C. Pseudo corrosion pits were visible on NO7208 and Ti6Al4V alloy at 35°C. At 70°C, total surface degradation was visible on Ti6Al4V and grain boundary corrosion on NO7208.

As a consequence of increased axle loads and speeds of trains on modernised railway lines, there may occur problems with bearing capacity and stability of the subgrade in some sections of the railway network. This is the situation we are dealing with right now on the Polish State Railways network. Therefore, as a case study, a fragment of an existing railway embankment based on a weak foundation was chosen for the analysis of train–track–subgrade interaction. A two-stage train–track–subgrade model has been developed. The model consists of the upper part (train–track) and the lower part (subgrade-foundation). The first part is modelled as a self-contained system of differential equations which are solved by means of finite difference method and yield the stress levels on the subgrade. These stresses are treated as a load for the lower system modelled using FEM. The model has been validated using experimental data from literature, authors’ measurements, and railway staff measurements of the track geometry. Several cases of strengthening methods were calculated and compared with measurements on the railway section under consideration. Good agreement between the prediction and the measurement was found. The novelty of the model is including the heterogeneity of the subgrade, the strengthening methods, and very deep layers of its foundation as well as adding the influence of vibration on the weakening of soils. It was found that this influence is noticeable and should be included in the prediction of railway subgrade behaviour

This work considers flexible manufacturing operations based on reconfigurable robotic skills and their usage in fully automated service manufacturing. In agile and ultra-flexible manufacturing operations, where lot sizes go down to one, the setup and execution of new tasks must be instant. We extend service manufacturing towards applications of multi-purpose autonomous mobile robots. We take digital data and service-oriented approach to configure and utilize re-usable robot operations formulated as robot skills. We integrate service requests, and system and robot skill models for an easily executable manufacturing service system. We show the feasibility of our approach by experimental tests with merged indoor logistics, assembly, and finishing tasks.

The Internet-of-things (IoT) concept is based on networked, mobile, and sensor-equipped microelectronic devices. They are capable of reacting to their environment by collecting and processing data, computing, and communicating with other IoT devices and the cloud. The deployment of artificial intelligence (AI) to IoT, referred to as artificial intelligence of things (AIoT), enables intelligent behavior for the whole cyber-physical system whether it is designed for human co-operation, completely autonomous operations, or something in between. The IoT devices, including smart phones and wearables, can be applied in a plethora of applications ranging from building automation and industrial systems to self-driving vehicles and health services. The distributed and growing usage of the connected devices deliver the users more responsive and intelligent support for decision-making in a given environment. The foundation of AI is based on data fed to algorithms for machine learning (ML). They require a lot of processing power due to the amount of data and recursive/concurrent nature of calculation. Until recently, this has been accomplished mainly in the cloud environment, where the raw data is uploaded into. This exposes all the data, even private and sensitive data, to the transmission phase and processing system. In conjunction with IoT, there is a possibility to perform ML closer to the origin of data concerning local intelligence. It means that only the results of local or edge ML are transmitted to cloud for more general aggregation of AI. Local systems do not need to send the raw data anymore, which helps on prevailing the privacy and security of the data. This type of ML is referred to as federated/collaborative learning. This study focuses on finding the existing and/or recommended solutions for up-to-date AI close to the devices. First, definitions of devices are reviewed to find out classifications of their capacity to contribute for the computation and scalability. Second, other computing and serving options between devices and the cloud are studied. Those are referred to as Fog/Edge services, and they are more stationary than the IoT devices. Third, the facts learned are being applied in two use cases to support the discussion and applicability of AIoT in practice. The main conclusion is that currently there are no single solutions – neither hardware nor software – for solving all the identified requirements were found. Instead, there are multiple options from mutually connected devices via middle-layer support to cloud services and distributed learning, respectively.

Autonomous mobile machines are applied increasingly often in outdoor applications, but only in places, where logistic problems and safety issues are resolvable. Solving safety issues require good hazard identification and risk estimation. The aim of this study is to show which new risks emerge in autonomous mobile machines compared to manual machines. There are new risks, which are valid only in autonomous mobile machines (e.g., related to sensors for situational awareness), and risks, which exist in both machine types, but human presence can make the difference in resolving the situation. Humans can take sophisticated protective measures during an unexpected hazardous situation. Another aim of this work is to give information to designers and assessors to consider risks of their own design. Autonomous mobile machines are complex, and their performance is not always easily predictable. A checklist of risks would help an assessor, but currently, it may be difficult to find a checklist for a specific autonomous mobile machine. The main result of this study is a checklist of new risk sources or hazards of autonomous mobile machines.

Research has been undertaken to analyze the possibilities of using the residual magnetic field, as a result of local changes in the electromagnetic properties of the rope material, for identification of steel wire rope technical condition. Under the influence of cyclically changing workloads, due to the effects of magnetomechanics, changes in electromagnetic properties occur both in the wires and in the entire rope. The article presents the use of magnetic sensors to determine the relationship between the number of steel wire rope bends and its magnetic field induction value. This knowledge, referred to as ropes working on real objects, allows us to determine the state of stress prevailing in them as well as their technical condition.

Coating–substrate adhesive joints are used in mechanical engineering and automotive vehicle construction. Monitoring their condition, both at the manufacturing and operational stages, is important for durability and extended lifetime. The article proposes a method for continuous monitoring of the state of the coating–substrate joint using ultrasonic surface wave. The waveforms of ultrasonic parameters such as gain of pulse of ultrasonic wave, resonant frequency and bandwidth over the lifetime of the tested joint were determined. The resonant frequency change precedes the final stage of degradation of the coating–substrate connection, which leads to complete detachment of the coating from the body sheet. Both, during the period of constitution and degradation, rapid changes in the pulse gain of the ultrasonic surface wave were recorded. The knowledge about the waveforms of the selected ultrasonic wave parameters makes it possible to assess the condition of the joint and is the basis for deciding on its further operation or repair.

Structural materials under various mechanical loads are damaged as a result of their plastic deformation and subsequent nucleation and propagation of cracks. Detection of damage in its initial phase is crucial to ensure safety and durability of construction elements. In this work, we proposed contact stiffness ( S S ) determined using the instrumented indentation technique as the damage indicator. New procedure for deformation-induced damage investigation is proposed and the indentation tests were performed in the specially designed specimens made from Inconel 718 alloy, which was previously subjected to mechanical loads. Damage parameter ( D ε {D}_{\varepsilon } ) determined on the basis of Johnson–Cook damage model was used as a reference measure of damage degree. Fracture analysis was carried out to investigate the early stage of damage development in the tested specimens. The value of contact stiffness determined from the instrumented indentation shows linear correlation with the value of damage parameter. This innovative approach was used in the presented investigation.

This work presents an attempt to identify local changes in materials caused by local grinding burnings by using the eddy current (EC) method. The locally heat-treated AISI 9310 steel specimen was prepared by using a laser surfacing process to imitate three different grinding burns. These burn marks were characterized in terms of changes in microstructure and hardness on the surface and cross-section of the specimen. On such a basis, the depth of the heat-affected zone caused by the grinding tool was examined. Subsequently, the specimen was subjected to the EC measurements for the quantitative description of the signal from each of the defects by using a commercial NORTEC 600D flaw detector working in specimen scanning mode and with a pencil probe. The changes in the amplitude and the phase angle of the signal from three defects indicate the possibility to identify burns along with their quantitative description and subsequent estimation of their depth. The differences in the phase angle value, related to the local changes in the stress state, serve as an effective indicator of the specimen overheating degree in the area of the EC induction.

This article discusses the research to determine the suitable magnetorheological (MR) damper model to produce the damping force generated by the sliding mode control (SMC) strategy. The MR damper models studied are parametric, i.e., the Bingham model, the Bouc-Wen model, and the Bouc-Wen model with a hyperbolic tangent function. The damping force of SMC usually includes sudden changes in the force and chattering. The research was carried out by calculating the value of the similarity measure of the damping force of the controller and the damping force of each model. The results show that the two Bouc Wen models had a high similarity measure. The Bouc Wen model with the hyperbolic tangent function was selected because it provides a sudden change of force and reasonable force tracking needed to develop the inverse MR damper model.