Band 7, Heft 1

In the process of estimating the thrust of an aircraft engine, there is a big problem that the differential pressure signal has large fluctuation. To deal with this problem, we develop an effective and robust adaptive de-noising algorithm based on domain transform combined with wavelet transform (D-WT). First, we do the domain transform for the signal, then sample the transformed signal, and finally the wavelet threshold transform is performed for the signal. Compared with the traditional wavelet transforms, the D-WT method filters the noise effectively and keeps more details.

This paper presents a robotic test stand for the ultrasonic transmission tomography (UTT) inspection of stator vane thickness. The article presents the method of the test stand design in Autodesk Robot Structural Analysis Professional 2013 software suite. The performance of the designed test stand solution was simulated in the RobotStudio software suite. The operating principle of the test stand measurement system is presented with a specific focus on the measurement strategy. The results of actual wall thickness measurements performed on stator vanes are presented.

This paper presents statistical analyses of rock engineering properties and the measured penetration rate of tunnel boring machine (TBM) based on the data of an actual project. The aim of this study is to analyze the influence of rock engineering properties including uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), rock brittleness index (BI), the distance between planes of weakness (DPW), and the alpha angle (Alpha) between the tunnel axis and the planes of weakness on the TBM rate of penetration (ROP). Four (4) statistical regression models (two linear and two nonlinear) are built to predict the ROP of TBM. Finally a fuzzy logic model is developed as an alternative method and compared to the four statistical regression models. Results show that the fuzzy logic model provides better estimations and can be applied to predict the TBM performance. The R-squared value (R 2 ) of the fuzzy logic model scores the highest value of 0.714 over the second runner-up of 0.667 from the multiple variables nonlinear regression model.

The problem of an unsteady MHD Casson fluid flow towards a stretching surface with cross diffusion effects is considered. The governing partial differential equations are converted into a set of nonlinear coupled ordinary differential equations with the help of suitable similarity transformations. Further, these equations have been solved numerically by using Runge-Kutta fourth order method along with shooting technique. Finally, we studied the influence of various non-dimensional governing parameters on the flow field through graphs and tables. Results indicate that Dufour and Soret numbers have tendency to enhance the fluid velocity. It is also found that Soret number enhances the heat transfer rate where as an opposite result is observed with Casson parameter. A comparison of the present results with the previous literature is also tabulated to show the accuracy of the results.

This paper reports an experimental comparison between the use of the refrigerants R409A and R437A in a heat pump unit designed and developed to work with R12. Although the use of both refrigerants in new equipments were abolished in EU and US according the new F-Gas Regulation of EU and SNAP, they still being used as options for R12 in old equipments, especially in developing countries. Both refrigerants were studied for the same test conditions, according to two groups of tests: group A (variation of the heat source temperature) and group B (variation of refrigerant flow rate). The results obtained showed that the R437A presents a higher discharge pressure and a lower discharge temperature. The heating and cooling capacities of both refrigerants were similar, as well as the exergetic efficiency. For the group A of tests the COP of both refrigerants was similar and for the group B of tests the R409A presented an average COP 15% higher. According to the results obtained it is recommended the use of R409A in old equipments (as transition refrigerant) until the acquisition of equipments operating with refrigerants with low-GWP becomes technically and economic feasible.

The impact phenomenon is inseparable part of every physical things, from substantial particle until macrostructure namely ship. In ship collisions, short-period load is distributed during impact process from striking ship into struck ship. The kinetic energy that is used to move striking ship is absorbed by struck ship that makes its structure undergoes plastic deformation and failure. This paper presents study that focuses on predicting occurred damage on side hull of struck ship for various impact scenario models. These scenarios are calculated by finite element approach to obtain characteristic on damage, energy as well as load during and after impact processes. The results indicate that the damages on impact to longitudinal components such as main and car decks are smaller than impact to transverse structure components. The damage and deformation are widely distributed to almost side structures including inner structure. The width between outer and inner shells is very affecting the damage mode where the width below the two meters will make inner shell experience damage beyond plastic deformation. The contribution of structure components is proofed deliver significant effect to damage mode and material strengths clearly affect the results in energy and load characteristic.

This article describes a method of in-situ process monitoring in the digital light processing (DLP) 3D printer. It is based on the continuous measurement of the adhesion force between printing surface and bottom of a liquid resin bath. This method is suitable only for the bottom-up DPL printers. Control system compares the force at the moment of unsticking of printed layer from the bottom of the tank, when it has the largest value in printing cycle, with theoretical value. Implementation of suggested algorithm can make detection of faults during the printing process possible.

In automotive industry plants, which use injection molding machines for rubber processing, tar contaminates air to such an extent that air fails to enter standard heat recovery systems. Accumulated tar clogs ventilation heat recovery exchangers in just a few days. In the plant in which the research was conducted, tar contamination causes blockage of ventilation ducts. The effect of this phenomenon was that every half year channels had to be replaced with new ones, since the economic analysis has shown that cleaning them is not cost-efficient. Air temperature inside such plants is often, even in winter, higher than 30°C. The air, without any means of heat recovery, is discharged outside the buildings. The analyzed plant uses three types of media for production: hot water, cold water at 14°C (produced in a water chiller), and compressed air, generated in a unit with a rated power consumption of 180 kW. The aim of the study is to determine the energy efficiency improvement of this type of manufacturing plant. The main problem to solve is to provide an air purification process so that air can be used in heat recovery devices. The next problem to solve is to recover heat at such a temperature level that it would be possible to produce cold for technological purposes without air purification. Experimental studies have shown that air purification is feasible. By using one microjet head, a total of 75% of tar particles was removed from the air; by using 4 heads, a purification efficiency of 93% was obtained. This method of air purification causes air temperature to decrease from 35°C to 20°C, which significantly reduces the potential for heat recovery. The next step of the research was designing a cassette-plate heat exchanger to exchange heat without air purification. The economic analysis of such a solution revealed that replacing the heat exchanger with a new one even once a year was not cost-efficient. Another issue examined in the context of energy efficiency was the use of waste heat from the air compressor. Before any changes, the heat was picked up by a chilled water system. The idea was to use the heat for cold generation. Temperature of oil and air in the compressor exceeds 65°C, which makes it a perfect heat source for an adsorption refrigeration device. This solution reduced the cooling demand by 147 kW, thus reducing power consumption by 36.75 kW. This study shows that even in factories where air is heavily polluted with tar, there are huge potentials for energy recovery using existing technical solutions. It is important to note that problems of this kind should always be approached individually.

This study proposes cyclic yield strength as a potential characteristic of safe design for structures operating under fatigue and creep conditions. Cyclic yield strength is defined on a cyclic stress-strain curve, while monotonic yield strength is defined on a monotonic curve. Both values of strengths are identified using a two-step procedure of the experimental stress-strain curves fitting with application of Ramberg-Osgood and Chaboche material models. A typical S-N curve in stress-life approach for fatigue analysis has a distinctive minimum stress lower bound, the fatigue endurance limit. Comparison of cyclic strength and fatigue limit reveals that they are approximately equal. Thus, safe fatigue design is guaranteed in the purely elastic domain defined by the cyclic yielding. A typical long-term strength curve in time-to-failure approach for creep analysis has two inflections corresponding to the cyclic and monotonic strengths. These inflections separate three domains on the long-term strength curve, which are characterised by different creep fracture modes and creep deformation mechanisms. Therefore, safe creep design is guaranteed in the linear creep domain with brittle failure mode defined by the cyclic yielding. These assumptions are confirmed using three structural steels for normal and high-temperature applications. The advantage of using cyclic yield strength for characterisation of fatigue and creep strength is a relatively quick experimental identification. The total duration of cyclic tests for a cyclic stress-strain curve identification is much less than the typical durations of fatigue and creep rupture tests at the stress levels around the cyclic yield strength.

Alkaline water electrolysis powered by renewable energy sources is one of the most promising strategies for environmentally friendly hydrogen production. However, wind and solar energy sources are highly dependent on weather conditions. As a result, power fluctuations affect the electrolyzer and cause several negative effects. Considering these limiting effects which reduce the water electrolysis efficiency, a novel operation strategy is proposed in this study. It is based on pumping the electrolyte according to the current density supplied by a solar PV module, in order to achieve the suitable fluid dynamics conditions in an electrolysis cell. To this aim, a mathematical model including the influence of electrode-membrane distance, temperature and electrolyte flow rate has been developed and used as optimization tool. The obtained results confirm the convenience of the selected strategy, especially when the electrolyzer is powered by renewable energies.

An intuitionistic fuzzy TOPSIS model, which is based on an exponential-related function (IF-TOPSIS) and a fuzzy entropy method, has been proposed in this study. The exponential-related function, which represents the aggregated effect of positive and negative evaluations in the performance ratings of the alternatives, based on the intuitionistic fuzzy set (IFS) data. Serves, as a computational tool for measuring the separation distance of decision alternatives from the intuitionistic fuzzy positive and negative ideal solution to determine the relative closeness coefficient. The main advantage of this new approach is that (1) it uses a subjective and objective based approach for the computation of the criteria weight and (2) its simplicity both in its concept and computational procedures. The proposed method has successfully been implemented for the evaluation of some engineering designs related problems including the selection of a preferred floppy disk from a group of design alternatives, the selection of the best concept design for a new air-conditions system and finally, the selection of a preferred mouse from a group of alternatives as a reference for a new design. Also, for each of the three case studies, the method has been compared with some similar computational approaches.

Evaluation of software quality is an important aspect for controlling and managing the software. By such evaluation, improvements in software process can be made. The software quality is significantly dependent on software usability. Many researchers have proposed numbers of usability models. Each model considers a set of usability factors but do not cover all the usability aspects. Practical implementation of these models is still missing, as there is a lack of precise definition of usability. Also, it is very difficult to integrate these models into current software engineering practices. In order to overcome these challenges, this paper aims to define the term ‘usability’ using the proposed hierarchical usability model with its detailed taxonomy. The taxonomy considers generic evaluation criteria for identifying the quality components, which brings together factors, attributes and characteristics defined in various HCI and software models. For the first time, the usability model is also implemented to predict more accurate usability values. The proposed system is named as fuzzy hierarchical usability model that can be easily integrated into the current software engineering practices. In order to validate the work, a dataset of six software development life cycle models is created and employed. These models are ranked according to their predicted usability values. This research also focuses on the detailed comparison of proposed model with the existing usability models.

We present exact solutions for new (3+1)-dimensional nonlinear equations of wave propagation and fluids. We use the tanh/sech method combined with a computer symbolic system for a reliable treatment of this work. We determine a variety of exact solutions for each equation that contains soliton, kink and periodic solutions. The constraints that guarantee the existence of soliton and kink solutions were examined and found to be related to the coefficients k , r and s of the space variables x , y , and z respectively.

This article deals with the investigation of three-dimensional axisymmetric steady flow of micropolar fluid over a rotating disk in a slip-flow regime. Further, the generation of entropy due to heat transfer and fluid friction is identified. It is noticed that the entropy generation can be decreased and controlled in the presence of slip. The anisotropic slip has vital characteristics and it has a great influence on the flow field and heat transfer. The von Kármán similarity transformation is used to establish the equations governing the flow and heat transfer characteristics of the fluid. The impact of some important parameters on velocity profiles, angular velocity (microrotation) and energy distribution is discussed and illustrated through graphs and tables. The effects of physical parameters on the entropy generation and Bejan numbers are also presented graphically. In addition, the most favorable agreement is observed among the results of the present study and those of the earlier studies.

The application of different mode-shape expansion (MSE) methods to a CFRP based on model order reduction (MOR) and component mode synthesis (CMS) methods is evaluated combining the updated stiffness parameters of the full FE model obtained with a mix-numerical experimental technique (MNET) in a previous work. The eigenvectors and eigenfrequencies of the different MSE methods obtained are compared with respect to the experimental measurements and with a full FE model solutions using the modal assurance criteria (MAC). Furthermore, the stiffness and mass weighted coefficients (K-MAC and M-MAC respectively) are calculated and compared to observe the influence of the different subspace based expansion methods applying the MAC criteria. The K-MAC and M-MAC are basically the MAC coefficients weighted by a partition of the global stiffness and mass matrices respectively. The best K-MAC and M-MAC results per paired mode-sensor are observed in the subspace based expansion MODAL/SEREP and MDRE-WE methods using the updated stiffness parameters. A strong influence of the subspace based on MOR using MSE methods is observed in the K-MAC and M-MAC criteria implemented in SDTools evaluating the stiffness parameters in a contrieved example.

In the new competitive electric world, it is compulsory for the electrical industry to make effective utilization of the available resources. Optimal tuning of generators and implementation of FACTS devices has been found to be very effective in this regard. In this paper, a combination strategy of optimal tuning of generators using Krill herd (KH) algorithm in the presence of Static VAR Compensator (SVC) has been proposed. A combinatory index (CI), which is a combination of Vi/Vo index and L-index, has been formulated and verified for obtaining the optimal location of SVC. A multi objective function has been formulated for tuning the generators. The results obtained after performing Optimal Power Flow on an IEEE 30 bus system for normal loading and for severe system conditions due to line outage in the presence of SVC using KH has been verified with that of GA, to prove the effectiveness of the chosen methodology.

One way that helps maintain the sustainability of agro-ecosystems land is the application of compost from municipal solid waste as fertilizer, because it can recover the nutrients contained in them, minimizing the negative impact on the environment. Composting as a method for preparing organic fertilizers and amendments is economically and ecologically sound and may well represent an acceptable solution for disposing of municipal solid waste. In the present work, the quality of compost is studied made from municipal solid waste; the content of mineral nutrients: potassium, calcium, magnesium, sodium, zinc, manganese, cupper, iron, nickel, chromium and lead has been investigated. The objective was to evaluate the changes in mineral nutrient concentration during the composting process. The compost was prepared in a pilot-plant using the turning-pile system. Temperature was used as a monitoring parameter to follow the composting progress, which underwent the typical trend of municipal solid waste composting mixtures. The results showed a similar evolution on the content of mineral nutrients of the mixture of municipal solid waste. This evolution originated in a mature compost (end sample) with an adequate content of mineral elements and physical-chemical characteristics for its use in agriculture. So, the use of compost of municipal solid waste represents an important tool for fertilization requirements for its use in agriculture.

The reinforcing effect of fibers in cement composites often results in the improvement of the brittle nature of cementitious materials. But the decrease in the workability of fresh concrete is often the disadvantage of fibers addition. Conventional single-point workability tests cannot characterize workability of concrete in terms of fundamental rheological parameters. To this end, this paper describes an investigation of the influence of synthetic fiber additions (fiber length in the range 12–50 mm and volume fraction in the range 0–4%) on the rheological properties of fiber reinforced fresh mortar (FRFM) and development of these properties over time. The rheometer Viskomat XL was used in this study. Within the limitations of the instrument and testing procedure it is shown that FRFMs conform to the Bingham model. Natural postglacial sand 0/4 mm was used as a fine aggregate and cement CEMI 42.5 R was used as a binder. Three commercial synthetic fibers were selected for these examinations. Rheological properties were expressed in terms of Bingham model parameters g (yield value ) and h (plastic viscosity). Based on the test results it was found out that the fiber type and volume fraction affected both the yield stress and plastic viscosity.

The paper presents the results of model tests conducted for a flood embankment under varying conditions of saturation. Test embankments were formed from the natural sea sand. The test apparatus consisted of the box with internal dimensions 200 × 100 × 4.5 cm, and thus ensured the implementation of the plane strain state. In most tests during watering air entrapment was observed, leading to formation of open soil discontinuities, called macropores (their dimensions many times exceeded the grain size of the soil skeleton). Analysis of images from a number of tests allowed to create a simplified model of the evolution of a macropore. The numerical model has been based on the finite element method using the PLAXIS 2D software. A comparison has been made between the observation of the phenomena occurring in the physical model and the results of the simulation of the phenomena in the numerical model. A correlation has been proven between the results acquired in reality and the results derived from the numerical model.

We describe an engineering solution to manufacture electromagnetic linear actuators for moving rudders and fin stabilizers of military ships Italian Ministry of Defence, General Direction of Naval Equipments (NAVARM), Projects ISO (2012-2014) and EDDA (2015-2017). . The solution defines the transition from the conceptual design of the device initially studied from an electromagnetic point of view to mechanical configurations that really work. The structural problems that have been resolved with the proposed configuration are described. In order to validate the design choices discussed we illustrate some results of the numerical simulations performed by the structural finite elements method. These results quantitatively justify the suggested mechanical solution by evaluating stresses and deformations in a virtual prototype of the structure during its functioning. The parts of the device that have been studied are the most critical because in cases of excessive deformation/stress, they can irreparably compromise the actuator operation. These parts are the pole piece-base set and the retention cages of the permanent magnets. The FEM analysis has allowed us to identify the most stressed areas of the previous elements whose shape has been appropriately designed so as to reduce the maximum stresses and deformations. Moreover, the FEM analysis helped to find the most convenient solution to join the pole pieces to the respective bases. The good results obtained by the suggested engineering solution have been experimentally confirmed by tests on a small prototype actuator purposely manufactured. Finally, a qualitative analysis of the engineering problems that have to be considered to design electromagnetic linear actuators bigger than the one already manufactured is illustrated.

The quality of the autoclaved aerated concrete (AAC) strongly depends on the chemical composition of the raw materials, as well as on the process of the hydrothermal reaction during autoclaving. Performance parameters depend on material structure: fine micron-scale matrix porosity generated by the packing of thin tobermorite plates and coarse aeration pores arising from the foaming of wet mix. In this study the binder varied in calcium sulfate dihydrate (CaSO 4 ⋅2H 2 O) content. Five series of AAC specimens were produced, with gypsum content 0; 0.55; 1.15; 2.3 and 3.5% of dry mass respectively. AAC units were produced in UNIPOL technology. The study presents experimental results of AAC moisture stabilization. The initial moisture content was determined directly after autoclaving. Slower drying process was observed for samples containing over 2% of gypsum. Whereas other performance parameters, compressive and tensile strength, as well as water absorption and capillary rise, were significantly better comparing to the reference AAC samples.

In this paper, theoretical analysis of microstrip line fed rectangular patch antenna loaded with parasitic element and split-ring resonator is presented. The proposed antenna shows that the dualband operation depends on gap between parasitic element, split-ring resonator, length and width of microstrip line. It is found that antenna resonates at two distinct resonating modes i.e., 0.9 GHz and 1.8 GHz for lower and upper resonance frequencies respectively. The antenna shows dual frequency nature with frequency ratio 2.0. The characteristics of microstrip line fed rectangular patch antenna loaded with parasitic element and split-ring resonator antenna is compared with other prototype microstrip line fed antennas. Further, the theoretical results are compared with simulated and reported experimental results, they are in close agreement.

Proton exchange membrane fuel cells (PEMFC) not only offer more efficient electrical energy conversion, relative to on-ground/backup turbines but generate by-products useful in aircraft such as heat for ice prevention, deoxygenated air for fire retardation and drinkable water for use on-board. Consequently, several projects (e.g. DLR-H2 Antares and RAPID2000) have successfully tested PEMFC-powered auxiliary unit (APU) for manned/unmanned aircraft. Despite the progress from flying PEMFC-powered small aircraft with 20 kW power output as high as 1 000 m at 100 km/h to 33 kW at 2 558 m, 176 km/h [1, 2, 3], durability and reliability remain key challenges. This review reports on the inadequate understanding of behaviour of PEMFC under aeronautic conditions and the lack of predictive methods conducive for aircraft that provide real-time information on the State of Health of PEMFCs. Highlights: The main research findings are – To minimize performance loss due to high altitude and inclination by adjusting cathode stoichiometric ratio. – To improve quality of oxygen-depleted air by controlling operating temperature and stoichiometric ratio. – Need to devise real time prediction methods conducive for determining PEMFC SoH in aircraft.

The contribution deals with the laser marking as one of the progressive and environment friendly technologies with utilisation in many branches of industry. Engraving and other types of laser marking of different types of materials are very actual technologies these days. Laser marking decreases the waste creation in comparison with the other classical marking technologies, which use paintings or created chips. In this experimental investigation the laser marking surface texturing of material AL99,7 according to STN 42 4003:1993-08 (STN EN 573) has been conducted. The laser marking machine TruMark 6020 and software TruTops Mark were used. Laser surface texturing after laser marking has been realised under different combinations of process parameters: pulse frequency, pulse energy and laser beam scanning speed. The morphological characterization of engraving or annealing surfaces has been performed using scanning electron microscopy (SEM) technique. The evaluation of roughness of engraved surfaces has been realized according to STN EN ISO 4287 by using Surftest SJ 301. The aim of the contribution was to show how different laser parameters affect the surface texture and colour change of metallic materials while creating minimal waste.

The paper presents the results of laboratory tests, that verify the correlation between the grain-size characteristics of non-cohesive soils and the value of the dynamic shear modulus. The problem is a continuation of the research performed at the Institute of Soil Mechanics and Rock Mechanics in Karlsruhe, by T. Wichtmann and T. Triantafyllidis, who derived the extension of the applicability of the Hardin’s equation describing the explicite dependence between the grain size distribution of sands and the values of dynamic shear modulus. For this purpose, piezo-ceramic bender elements generating elastic waves were used to investigate the mechanical properties of the specimens with artificially generated particle distribution. The obtained results confirmed the hypothesis that grain size distribution of non-cohesive soils has a significant influence on the dynamic shear modulus, but at the same time they have shown that obtaining unambiguous results from bender element tests is a difficult task in practical applications.

The objective of this research was to obtain thermal performance data for reflective insulations in a South East Asia environment. Thermal resistance data (RSI, m 2 ⋅ K/W) for reflective insulations are well established from 1-D steady-state tests, but thermal data for reflective insulation in structures like those found in South East Asia are scarce. Data for reflective insulations in South East Asia will add to the worldwide database for this type of energy-conserving material. RSI were obtained from heat flux and temperature data of three identical structures in the same location. One unit did not have insulation above the ceiling, while the second and third units were insulated with reflective insulation with emittance less than 0.05. RSI for the uninsulated test unit varied from 0.37 to 0.40 m 2 ⋅ K/W. RSI for a single-sheet reflective insulation (woven foil) varied from 2.15 to 2.26 m 2 ⋅ K/W, while bubble-foil insulation varied from 2.69 to 3.09 m 2 ⋅ K/W. The range of RSI values resulted from differences in the spacing between the reflective insulation and the roof. In addition, the reflective insulation below the roof lowered attic temperatures by as much as 9.7° C. Reductions in ceiling heat flux of 80 to 90% relative to the uninsulated structure, due to the reflective insulation, were observed.

Background Precious metal alloys can be supplied in traditional plate form or innovative drop form with high degree of purity. Objective The aim of the present work is to evaluate the influence of precious metal alloy form on metallurgical and mechanical properties of the final dental products with particular reference to metal-ceramic bond strength and casting defects. Method A widely used alloy for denture was selected; its nominal composition was close to 55 wt% Pd – 34 wt% Ag – 6 wt% In – 3 wt% Sn. Specimens were produced starting from the alloy in both plate and drop forms. A specific test method was developed to obtain results that could be representative of the real conditions of use. In order to achieve further information about the adhesion behaviour and resistance, the fracture surfaces of the samples were observed using ‘Scanning Electron Microscopy (SEM)’. Moreover, material defects caused by the moulding process were studied. Results The form of the alloy before casting does not significantly influence the shear bond strength between the metal and the ceramic material (p-value=0,976); however, according to SEM images, products from drop form alloy show less solidification defects compared to products obtained with plate form alloy. This was attributed to the absence of polluting additives used in the production of drop form alloy. Conclusions This study shows that the use of precious metal denture alloys supplied in drop form does not affect the metal-ceramic bond strength compared to alloys supplied in the traditional plate form. However, compared to the plate form, the drop form is found free of solidification defects, less expensive to produce and characterized by minor environmental impacts.

In this article, a mathematical description of tooth flank surface of the globoidal worm and worm wheel generated by the hourglass worm hob with straight tooth axial profile is presented. The kinematic system of globoidal worm gear is shown. The equation of globoid helix and tooth axial profile of worm is derived to determine worm tooth surface. Based on the equation of meshing the contact lines are obtained. The mathematical description of globoidal worm wheel tooth flank is performed on the basis of contact lines and generating the tooth side by the extreme cutting edge of worm hob. The presented mathematical model of tooth flank of TA worm and worm wheel can be used e.g. to analyse the contact pattern of the gear.

The Alto Douro Wine Region , located in the northeast of Portugal, a UNESCO World Heritage Site, presents an abundant vernacular building heritage. This building technology is based on a timber framed structure filled with a composite earth-based material. A lack of scientific studies related to this technology is evident, furthermore, principally in rural areas, this traditional building stock is highly deteriorated and damaged because of the rareness of conservation and strengthening works, which is partly related to the non-engineered character of this technology and to the knowledge loosed on that technique. Those aspects motivated the writing of this paper, whose main purpose is the physical and chemical characterization of the earth-based material applied in the tabique buildings of that region through field tests. Consequently, experimental work was conducted and the results obtained allowed, among others, the proposal of a series of adequate field tests. At our knowledge, this is the first time field tests are undertaken for tabique technology. This information will provide the means to assess the suitability of a given earth-based material with regards to this technology. The knowledge from this study could also be very useful for the development of future normative documents and as a reference for architects and engineers that work with this technology to guide and regulate future conservation, rehabilitation or construction processes helping to preserve this important legacy.

In recent machining operation, tool life is one of the most demanding tasks in production process, especially in the automotive industry. The aim of this paper is to study tool wear on HSS in end milling of aluminium 6061 alloy. The experiments were carried out to investigate tool wear with the machined parameters and to developed mathematical model using response surface methodology. The various machining parameters selected for the experiment are spindle speed (N), feed rate (f), axial depth of cut (a) and radial depth of cut (r). The experiment was designed using central composite design (CCD) in which 31 samples were run on SIEG 3/10/0010 CNC end milling machine. After each experiment the cutting tool was measured using scanning electron microscope (SEM). The obtained optimum machining parameter combination are spindle speed of 2500 rpm, feed rate of 200 mm/min, axial depth of cut of 20 mm, and radial depth of cut 1.0mm was found out to achieved the minimum tool wear as 0.213 mm. The mathematical model developed predicted the tool wear with 99.7% which is within the acceptable accuracy range for tool wear prediction.

Transport volume in the Slovak Republic is growing continuously every year. This rising trend is influenced by the development of car industry and its suppliers. Slovak republic has also a geographic strategy position in middle Europe from the side of transport corridors (east-west and north-south). The development of transport volume in freight transport depends on the transport and business processes between the European Union and China and it is an opportunity for Slovak republic to obtain transit transport flows. In the Slovak Republic, road transport has a dominant position in the transport market. The volume of road transport has gradually increased over the past years. The increase of road transport is reflected on the highways and speed roads in regions which have higher economic potential. The increase of rail transport as seen on the main rail corridors is not as significant as in road transport. Trade globalization also has an influence on the increase of transport volume in intermodal transport. Predicted increase in transport volume for this transport mode is from 2,3 mil ton per year at present to 8 mil ton in the year 2020. Selection of transport mode and carrier is an important aspect for logistic management, because companies (customers) want to reduce the number of carriers which they trade and they create the system of several key carriers. Bigger transport volume and more qualitative transport service give a possibility to reduce transport costs. This trend is positive for carriers too, because the carriers can focus only on the selected customers and provide more qualitative services. The paper is focused on the selection of transport mode based on the proposed methodology. The aims of the paper are, definition of criteria which directly influence the selection of transport modes, determination of criteria based on the subjectively methods, creation of process for the selection of transport modes and practical application of proposed methodology.

Global business is currently still influenced by the economic crisis and the economic development in each country of the EU. The construction sector is among the most affected sectors of the national economies. The production of building material is a part of the construction industry. Several companies of this sector in the European Union use business logistics effectively. The overall efficiency of the company is influenced by many various external and internal determinants, especially the distribution logistics.

This paper is focused on perceiving the logistic services as the competition advantage in frame of the ecommerce. Customers consider their purchases in its complexity and all the logistic services should be designed to meet with customers’ preferences as much as possible. Our aim was to identify and evaluate of customers perceiving in frame of sales proposals offered by e-shops. Collected data of research were processed with the usage of cluster analysis. The aim of this paper is to present the results and conclusions from this research with focus on the elements of logistics services within e-commerce. These outputs can be used for knowledge base of information systems through which enterprises evaluate their decisions and selection of variants. For the enterprise, it is important to appropriate decisions about resource allocation and design of the structure of logistics services were set based on real customer preferences.

This paper focuses on utilization of analysis of different possibilities of merging two production sites with the help of simulation model of company processes. Software SIMUL8 was chosen as a development environment for its possibility of dynamic discrete simulation of company processes. In the first phase, it analyses current status of both production sites. It is followed by suggesting several possible solutions for their potential merger. Each solution is analyzed with the help of simulation models. They have been evaluated and the optimal solution was selected.

Risk management facilitates risk identification, evaluation, control, and by means of appropriate set of measures, risk reduction or complete elimination. Therefore, the risk management becomes a strategic factor for a company’s success. Properly implemented risk management system does not represent a tool to avoid the risk; it is used to understand the risk and provide the bases for strategic decision-making. Risk management represents a key factor for the supply chain operations. Managing the risks is crucial for achieving the customer satisfaction and thus also a company’s success. The subject-matter of the article is the assessment of the supply chain in the automobile industry, in terms of risks. The topicality of this problem is even higher, as after the economic crisis it is necessary to revaluate the readiness of the supply chain for prospective risk conditions. One advantage of this article is the use of the Saaty method as a tool for the risk management within the supply chain.

Supply process is one of the most important enterprise activities. All raw materials, intermediate products and products, which are moved within enterprise, are the subject of inventory management and by their effective management significant improvement of enterprise position on the market can be achieved. For that reason, the inventory needs to be managed, monitored, evaluated and affected. The paper deals with utilizing the methods of the operational analysis in the field of inventory management in terms of achieving the economic efficiency and ensuring the particular customer’s service level as well.

Currently, when there is a need for transport services adapted to the customer requirements and create a workable operational system, there is increasing talk about transport terminals. Since the South Bohemian region is one of those where this issue will be increasingly dealt with, this paper suggests ways to use transport terminals as important support systems for freight and passenger transport.

In this article, the temperatures in transport of different types of perishable foodstuffs will be compared. The comparison will be made based on the evaluation of measurement data from the remote probe and compared with the temperature measured by a thermograph installed in the vehicle. The results will be compared with a tolerance listed in the individual regulations, laws and Agreement ATP (Agreement on the International Carriage of Perishable Foodstuffs and on the Special Equipment to be Used for such Carriage), which are further described in the first part of the article.

The contribution will focus on the development of e-commerce. The extent of the development of internet by age category will be assessed and the development of this factor will be monitored by correlation analysis. Analysis of logistics operators will be performed in the field courier, express and parcel shipments. Market competitiveness B2C will focus on flexibility in delivery, evening delivery or on weekends, term delivery (increasing the cost of tracking shipments and their records), use and offering banking products with secure payment system, readiness deliver the goods via its own fueling point. On the contrary, legal provision regulating the entrance to the parking are, entrance into pedestrian zone service may limit or prevent.

Difficult to cut materials such as nickel and titanium alloys are used in the aeronautical industry, the former alloys due to its heat-resistant behavior and the latter for the low weight - high strength ratio. Ceramic tools made out alumina with reinforce SiC whiskers are a choice in turning for roughing and semifinishing workpiece stages. Wear rate is high in the machining of these alloys, and consequently cutting forces tends to increase along one operation. This paper establishes the cutting force relation between work-piece and tool in the turning of such difficult-to-cut alloys by means of a mechanistic cutting force model that considers the tool wear effect. The cutting force model demonstrates the force sensitivity to the cutting engagement parameters (a p , f) when using ceramic inserts and wear is considered. Wear is introduced through a cutting time factor, being useful in real conditions taking into account that wear quickly appears in alloys machining. A good accuracy in the cutting force model coefficients is the key issue for an accurate prediction of turning forces, which could be used as criteria for tool replacement or as input for chatter or other models.

Nickel based superalloys offer high strength, corrosion resistance, thermal stability and superb thermal fatigue properties. However, they have been one of the most difficult materials to machine due to these properties. Although we are witnessing improved machining strategies with the developing machining, tooling and inspection technologies, machining of nickel based superalloys is still a challenging task due to in-process strains and post process part quality demands. Selecting optimum machining parameters for quality, productivity and profitability is of paramount importance. Many studies have been conducted on various aspects of machinability of nickel based superalloys including defining the optimum cutting parameters, to develop a better understanding of machining them. The recent studies suggest new findings, and discuss previously reported results, related to the concerns of superalloy machining. This review presents the influences of the most significant cutting parameters on various machinability characteristics with respect to the recent studies as well as the previous ones. The reviewed machinability characteristics may be listed as: tool wear, cutting forces and surface integrity.

We survey the areas of Desktop Grid task scheduling that seem to be insufficiently studied so far and are promising for efficiency, reliability, and quality of Desktop Grid computing. These topics include optimal task grouping, “needle in a haystack” paradigm, game-theoretical scheduling, domain-imposed approaches, special optimization of the final stage of the batch computation, and Enterprise Desktop Grids.

A volunteer computing project aimed at solving computationally hard inverse problems in underwater acoustics is described. This project was used to study the possibilities of the sound speed profile reconstruction in a shallow-water waveguide using a dispersion-based geoacoustic inversion scheme. The computational capabilities provided by the project allowed us to investigate the accuracy of the inversion for different mesh sizes of the sound speed profile discretization grid. This problem suits well for volunteer computing because it can be easily decomposed into independent simpler subproblems.

A regular Desktop Grid bag-of-tasks project can take a lot of time to complete computations. An important part of the process is tail computations: when the number of tasks to perform becomes less than the number of computing nodes. At this stage, a dynamic replication could be used to reduce the time needed to complete computations. In this paper, we propose a mathematical model and a strategy of dynamic replication at the tail stage. The results of the numerical experiments are given.

The LHC@Home BOINC project has provided computing capacity for numerical simulations to researchers at CERN since 2004, and has since 2011 been expanded with a wider range of applications. The traditional CERN accelerator physics simulation code SixTrack enjoys continuing volunteers support, and thanks to virtualisation a number of applications from the LHC experiment collaborations and particle theory groups have joined the consolidated LHC@Home BOINC project. This paper addresses the challenges related to traditional and virtualized applications in the BOINC environment, and how volunteer computing has been integrated into the overall computing strategy of the laboratory through the consolidated LHC@Home service. Thanks to the computing power provided by volunteers joining LHC@Home, numerous accelerator beam physics studies have been carried out, yielding an improved understanding of charged particle dynamics in the CERN Large Hadron Collider (LHC) and its future upgrades. The main results are highlighted in this paper.

The article deals with the problem of analysis of effectiveness of the heuristic methods with limited depth-first search techniques of decision obtaining in the test problem of getting the shortest path in graph. The article briefly describes the group of methods based on the limit of branches number of the combinatorial search tree and limit of analyzed subtree depth used to solve the problem. The methodology of comparing experimental data for the estimation of the quality of solutions based on the performing of computational experiments with samples of graphs with pseudo-random structure and selected vertices and arcs number using the BOINC platform is considered. It also shows description of obtained experimental results which allow to identify the areas of the preferable usage of selected subset of heuristic methods depending on the size of the problem and power of constraints. It is shown that the considered pair of methods is ineffective in the selected problem and significantly inferior to the quality of solutions that are provided by ant colony optimization method and its modification with combinatorial returns.

In this research, the study concerns around several features of diagonal Latin squares (DLSs) of small order. Authors of the study suggest an algorithm for computing minimal and maximal numbers of transversals of DLSs. According to this algorithm, all DLSs of a particular order are generated, and for each square all its transversals and diagonal transversals are constructed. The algorithm was implemented and applied to DLSs of order at most 7 on a personal computer. The experiment for order 8 was performed in the volunteer computing project Gerasim@home. In addition, the problem of finding pairs of orthogonal DLSs of order 10 was considered and reduced to Boolean satisfiability problem. The obtained problem turned out to be very hard, therefore it was decomposed into a family of subproblems. In order to solve the problem, the volunteer computing project SAT@home was used. As a result, several dozen pairs of described kind were found.

We consider the problem of packing the maximal number of unit squares in a hypograph of a function. A polynomial time algorithm is described to solve this problem for a piecewise linear function.

Chemical compositional simulation of enhanced oil recovery and surfactant enhanced aquifer remediation processes is a complex task that involves solving dozens of equations for all grid blocks representing a reservoir. In the present work, we perform a numerical validation of the newly developed mathematical formulation which satisfies the conservation laws of mass and energy and allows applying a sequential solution approach to solve the governing equations separately and implicitly. Through its application to the numerical experiment using a wettability alteration model and comparisons with existing chemical compositional model’s numerical results, the new model has proven to be practical, reliable and stable.

The aim of the study is to develop innovative intelligent technology and information systems of distance education for people with impaired vision (PIV). To solve this problem a comprehensive approach has been proposed, which consists in the aggregate of the application of artificial intelligence methods and statistical analysis. Creating an accessible learning environment, identifying the intellectual, physiological, psychophysiological characteristics of perception and information awareness by this category of people is based on cognitive approach. On the basis of fuzzy logic the individually-oriented learning path of PIV is con- structed with the aim of obtaining high-quality engineering education with modern equipment in the joint use laboratories.

The paper considers the implementation and verification of a test suite containing 150 benchmarks for global deterministic box-constrained optimization. A C++ library for describing standard mathematical expressions was developed for this purpose. The library automate the process of generating the value of a function and its’ gradient at a given point and the interval estimates of a function and its’ gradient on a given box using a single description. Based on this functionality, we have developed a collection of tests for an automatic verification of the proposed benchmarks. The verification has shown that literary sources contain mistakes in the benchmarks description. The library and the test suite are available for download and can be used freely.

Methodology of analysis of stability is expounded to the one contour systems automatic control feedback in the presence of non-linearities. The methodology is based on the use of the simplest mathematical models of the nonlinear controllable systems. Stability of program manifolds of one contour automatic control systems is investigated. The sufficient conditions of program manifold’s absolute stability of one contour automatic control systems are obtained. The Hurwitz’s angle of absolute stability was determined. The sufficient conditions of program manifold’s absolute stability of control systems by the course of plane in the mode of autopilot are obtained by means Lyapunov’s second method.

In this study the work presents the system designed for automated load balancing of the contributor by analysing the load of compute nodes and the subsequent migration of virtual machines from loaded nodes to less loaded ones. This system increases the performance of cluster nodes and helps in the timely processing of data. A grid system balances the work of cluster nodes the relevance of the system is the award of multi-agent balancing for the solution of such problems.