Band 18, Heft 1

Electron propagation in a trapped state between an insulator and a metal during very close contact in a triboelectric nanogenerator (TENG) system was considered in this study. A single energy level ( E 0 ) was assumed for the trap and wave function inside the trap, which is related to the ground state energy. The phase of the waveform in the metal (neglecting the rebound effect at the wall) was assumed very small ( δ′ ≪ 1) because of the large size of the metal. The contact distance between the trap and metal is very small, which allows us to ignore the vacuum potential. Based on our results, the probability of finding an electron inside the trap as a function of time was found to be in oscillation ( i.e ., back-and-forth propagation of the electron between the trap and metal leads to an equilibrium state). These results can be used to understand the quantum mechanisms of continuous contact, particularly in sliding-mode TENG systems.

Understanding the dynamic formation mechanism of online collective attention has been attracted diversified interests such as Internet memes, viral videos, or social media platforms and Web-based businesses, and has practical application in the area of marketing and advertising, propagation of information. Bulletin Board System, or BBS can be regarded as an ecosystem of digital resources connected and shaped by collective successive behaviors of users. Clicks and replies of the posts quantify the degree of collective attention. For example, the collective clicking behavior of users on BBS gives rise to the up and down of focus on posts, and transporting attention between topics, the ratio between clicks and replies measure the heat degree of a post. We analyzed the dynamics of collective attention millions of users on an interactive Tianya Zatan BBS. By analyzing the dynamics of clicks we uncovered a non-trivial Hawkes process self-exciting regularity concerning the impact of novelty exponential decay mechanism. Here, it able to explain the empirical data of BBS remarkably well, such as popular topics are observed in time frequently cluster, asymptotic normality of clicks. Our findings indicate that collective attention among large populations decays with a exponential decaying law, suggest the existence of a natural time scale over novelty fades. Importantly, we show that self-exciting point processes can be used for the purpose of collective attention modeling.

We investigate theoretically the entanglement in a hybrid Fabry-Perot cavity system. A membrane in the cavity acts as a mechanical resonator, and a two-level quantum dot is coupled to both the cavity mode and the mechanical resonator. The entanglements between the cavity field and the mechanical resonator, between the mechanical resonator and the quantum dot, as well as between the cavity field and the quantum dot are observed. The logarithmic negativities in the first two subsystems are much larger than those in the system without two-way coupled quantum dot, and the entanglements are robust against the thermal temperature (entanglements still exist in tens of Kelvin). We also find that without direct coupling between the cavity field and the mechanical resonator, one can till observe effective entanglement between them in our system. Our work is helpful and may have potential applications in the research of multipartite entanglement in physical system.

In this work, we construct traveling wave solutions of (1+1) - dimensional Ito integro-differential equation via three analytical modified mathematical methods. We have also compared our achieved results with other different articles. Portrayed of some 2D and 3D figures via Mathematica software demonstrates to understand the physical phenomena of the nonlinear wave model. These methods are powerful mathematical tools for obtaining exact solutions of nonlinear evolution equations and can be also applied to non-integrable equations as well as integrable ones. Hence worked-out results ascertained suggested that employed techniques best to deal NLEEs.

In this study the low visibility in Nanjing city is classified and predicted using observed data during 2014 to 2016 with machine-learning based decision tree algorithm (4.5). For this purpose, the model was trained with 3/4 th of the data samples until the self-learning accuracy of the model reached 88.32%. The remaining 1/4 th of the data samples were used to verify the model’s prediction ability, with the test accuracy reaching 88.34% indicating a good classification diagnosis effect of the model. The results produced with model, generated through learning from the training sample, it is found that the relative humidity, PM10 and PM2.5 are important factors in diagnosing “whether low visibility events will occur in Nanjing”: When relative humidity is favorable ( i.e . <90%) and PM2.5 concentration is not high enough ( i.e . <146), the probability of low visibility events may reduce; when relative humidity is relatively favorable ( i.e . ≥ 90%) with a PM10 concentration ≥ 59, low visibility events are more likely to occur; when relative humidity is extremely favorable ( i.e . ≥ 96%) with a low PM10 concentration ( i.e . <59), there is also a high probability that low visibility events will occur.

Fruit is not only delicious, but it also contains iron, potassium, magnesium, and other microelements necessary for the human body. Banana, pineapple and kiwifruit were selected as samples for testing. A laser with a wavelength of 532 nm was focused on the samples’ surface to generate a plasma. The emission spectrum of the atoms and ions in the plasma were collected by optical receivers, and the optimal condition was confirmed by analyzing the signal-to-noise ratio. The electronic temperature characteristics of the Fe plasma were studied under optimal experimental conditions. The maximum electron temperature of the Fe plasma occurred after a time delay of 300 ns in bananas, after 400 ns in pineapples and after 400 ns in kiwifruit. The electronic temperature of the Fe plasma increased with the time delay before the maximum point was reached. However, the temperature decreased after the maximum point was reached. At the beginning of the decline, the plasma decreased rapidly, but later decreased slowly. The range of the variation of the electron temperature of the Fe plasma in bananas, pineapples, and kiwifruits was 12388.29–19958.3 K, 11994.21–16856.4 K, and 13388.2–19607.32 K, respectively.

Basic structures of liquid-vapor separation cooling plates (LSCPs) and a liquid-vapor separation plate condenser (LVSPC) are innovatively designed. Strengthening heat transfer principle of the LSCPs is demonstrated by theoretical analysis. The average condensation heat transfer coefficients (ACHTCs) of the LSCPs are calculated and compared with conventional cooling plate (CCP). Results show that for a laminar flow, the ACHTCs of 2-parts liquid-vapor separation cooling plate and 3-parts liquid-vapor separation cooling plate are respectively 19% and 32% higher than the ACHTCs of the CCP in the same conditions. The ACHTC ratio of N-parts liquid-vapor separation cooling plates (NLSCP) to CCP is N 4 $\sqrt[4]{N}$in the same conditions. For a turbulent flow, results show the smaller the height of condensation area, the greater the ACHTCs of cooling plate. In the LVSPC study, operation conditions include the refrigerant R134a mass flux ranging from 22 to 32 kg/(m 2 .s) and inlet vapor quality from 0.5 to 1 for the saturated temperature of 40 ∘ C. Calculation results showed that the ACHTCs of the LVSPC are 6–24% higher than the ACHTCs of the given common plate condenser (CPC), and similar to the CPC, the ACHTCs of the LVSPC increases with the increase of mass flux and vapor quality.

A dielectric barrier discharge plasma controlled diffusion flame experimental system was built based on the designed coaxial swirling plasma injector. The air plasma was generated within the annulus gap of the injector by alternating current dielectric barrier discharge. The discharge characteristics and power of plasma injector under different actuation intensities and air flowrates were measured. Through the measurement techniques, such as schlieren imaging, broadband chemiluminescence image and CH* chemiluminescence, the effect and mechanism of plasma on ethylene-air normal diffusive jet and flame was explored. The results showed that a large number of filamentary discharge channels are formed in air plasma. The increase of air flowrates weakened the intensity of discharge to a certain extent. The induced jet generated by the plasma can short the laminar length of the ethylene-air jet, accelerate the transition of the flow jet, enhance the turbulence and the mixing of the fuel and the oxidizer. The higher the actuation intensity, the shorter distance of the cold jet transition zone, the higher the jet turbulence. Depending on the aerodynamic and kinetic effects, plasma can improve the stability of ethylene-air diffusive flame and reduce the lift height between the flame root and injector. The plasma can also expand the flammability limit of ethylene-air flame and make the flame ignited under some conditions that could not be. In addition, the CH* chemiluminescence shows that, in a certain range of discharge voltage, the heat release distribution can be changed on both sides of the flame, and its representative length are generally reduced as the voltage rises. On the contrary, the overtop voltage could lead to a decrease of flame heat release.

The double-diffusive tangent hyperbolic nanofluid containing motile gyrotactic microorganisms and magnetohydrodynamics past a stretching sheet is examined. By adopting the scaling group of transformation, the governing equations of motion are transformed into a system of nonlinear ordinary differential equations. The Keller box scheme, a finite difference method, has been employed for the solution of the nonlinear ordinary differential equations. The behaviour of the working fluid against various parameters of physical nature has been analyzed through graphs and tables. The behaviour of different physical quantities of interest such as heat transfer rate, density of the motile gyrotactic microorganisms and mass transfer rate is also discussed in the form of tables and graphs. It is found that the modified Dufour parameter has an increasing effect on the temperature profile. The solute profile is observed to decay as a result of an augmentation in the nanofluid Lewis number.

In this article, we study the two-flavor Nambu and Jona-Lasinio (NJL) phase diagrams on the T – μ plane through three regularization methods. In one of these, we introduce an infrared three-momentum cutoff in addition to the usual ultraviolet regularization to the quark loop integrals and compare the obtained phase diagrams with those obtained from the NJL model with proper time regularization and Pauli–Villars regularization. We have found that the crossover appears as a band with a well-defined width in the T – μ plane. To determine the extension of the crossover zone, we propose a novel criterion, comparing it to another criterion that is commonly reported in the literature; we then obtain the phase diagrams for each criterion. We study the behavior of the phase diagrams under all these schemes, focusing on the influence of the regularization procedure on the crossover zone and the presence or absence of critical end points.

In this article, a numerical model for a Brusselator advection–reaction–diffusion (BARD) system by using an elegant numerical scheme is developed. The consistency and stability of the proposed scheme is demonstrated. Positivity preserving property of the proposed scheme is also verified. The designed scheme is compared with the two well-known existing classical schemes to validate the certain physical properties of the continuous system. A test problem is also furnished for simulations to support our claim. Prior to computations, the existence and uniqueness of solutions for more generic problems is investigated. In the underlying system, the nonlinearities depend not only on the desired solution but also on the advection term that reflects the pivotal importance of the study.

The purpose of this study is to reduce the maintenance time, cost, and scheduling distance and to determine the maintenance priority of planned shop visit products. This study introduces the concept of maintenance map, establishes the evaluation indicators system of maintenance map from the perspective of organizational quality-specific immune, and puts forward two key dimensions named maintenance plan and technical support of maintenance map. Based on the theoretical framework, construct a heuristic decision model of planned shop visit products based on similar reasoning, set the maintenance services data of Harbin Dongan Engine Co., Ltd., as research objects, and use the concrete schemes and cases to solve and carry out an empirical analysis of the heuristic decision of planned shop visit products based on similar reasoning with the help of the ant colony algorithm; the empirical analysis results indicate that maintenance map and evaluation indicators system are the fundamental basis of the heuristic decision based on similar reasoning, the combinations of similar reasoning and ant colony algorithm can achieve the optimal heuristic decision of planned shop visit products, which have effectiveness, feasibility, and operability. This research will be conductive to give out the heuristic decision of scheduling schemes of planned shop visit products, which will be beneficial to enhance maintenance efficiency and quality, promote learning effects and learning pattern paths, and reduce maintenance scheduling distances of planned shop visit products from the aspects of theoretical framework guidance, empirical system enlightenment, and conceptual paradigm reference.

With the rapid development of traffic infrastructure in China, the problem of crystal plugging of tunnel drainage pipes becomes increasingly salient. In order to build a mechanism that is resilient to the crystal plugging of flocking drainage pipes, the present study used the numerical simulation to analyze the two-dimensional flow field distribution characteristics of flocking drainage pipes under different flocking spacings. Then, the results were compared with the laboratory test results. According to the results, the maximum velocity distribution in the flow field of flocking drainage pipes is closely related to the transverse distance h of the fluff, while the longitudinal distance h of the fluff causes little effect; when the transverse distance h of the fluff is less than 6.25 D ( D refers to the diameter of the fluff), the velocity between the adjacent transverse fluffs will be increased by more than 10%. Moreover, the velocity of the upstream and downstream fluffs will be decreased by 90% compared with that of the inlet; the crystal distribution can be more obvious in the place with larger velocity while it is less at the lower flow rate. The results can provide theoretical support for building a mechanism to deal with and remove the crystallization of flocking drainage pipes.

Building on the existing model, an improved constitutive model for rock is proposed and extended in three dimensions. The model can avoid the defect of non-zero dynamic stress at the beginning of impact loading, and the number of parameters is in a suitable range. The three-dimensional expansion method of the component combination model is similar to that of the Hooke spring, which is easy to operate and understand. For the determination of model parameters, the shared parameter estimation method based on the Levenberg–Marquardt and the Universal Global Optimization algorithm is used, which can be well applied to models with parameters that do not change with confinement and strain rates. According to the established dynamic constitutive equation, the stress–strain curve of rock under the coupling action of the initial hydrostatic pressure load and constant strain-rate impact load can be estimated theoretically. By comparing the theoretical curve with the test data, it is shown that the dynamic constitutive model is suitable for the rock under the initial pressure and impact load.

The traditional target recognition method for the remote sensing image is difficult to accurately identify the specified targets from the massive remote sensing image data. Based on the theory of multitemporal recognition, an automatic target recognition method for the remote sensing image is proposed in this article. The proposed recognition method includes four modules: automatic segmentation of multitemporal remote sensing image, automatic target extraction of multitemporal remote sensing image, automatic processing of multitemporal remote sensing image, and automatic recognition of multitemporal remote sensing image. The automatic segmentation of the image target is introduced. The effectiveness of the segmentation technology is verified through the kernel function bandwidth algorithm. Linear feature extraction is used to extract the segmented image. The image extraction processing is described, which includes image profile analysis, image preprocessing, image feature analysis, the region of interest localization, image enhancement processing, recognition processing, and result output. According to the theory of pattern recognition, three different feature recognition images are given, which are partial separable recognition, weakly separable recognition, and fully separable recognition, and then, a new image recognition method is designed. To verify the practical application effect of the recognition method, the proposed method is compared with the traditional recognition method. Experimental results show that the proposed method can accurately identify the specified objects from the massive remote sensing image data and has a high potential for development. This article has an important guiding significance for image recognition.

This paper presents optical Gaussons by the aid of the Laplace–Adomian decomposition scheme. The numerical simulations are presented both in the presence and in the absence of the detuning term. The error analyses of the scheme are also displayed.

Joint stabilizers and new technology stabilizers are hotspots of ship stabilizing technology research at the present stage. This study proposes a magnetic suspension stabilizing method; expounds the working principle of magnetic suspension stabilization, respectively; establishes the mathematical model of the magnetic suspension stator and the stabilization mass block and the mathematical model of magnetic stabilizer and ship; and stimulates the displacement, velocity, and acceleration. On the basis of the simulation, a set of magnetic suspension stabilizers have been designed; the stability of suspension has been tested; and, respectively, the acceleration value of stator and stabilization mass block has been measured by loading 0–500 Hz sine voltage excitation signal on electromagnetic coil; thus, the feasibility of the magnetic suspension stabilizer has been verified.

To study the dynamic response characteristics of 93W alloy spherical component under high overload, the deformation patterns of the 93W spherical component under different overloads are obtained by the sphereistic impact test, and the microscopic response characteristics are studied by the metallographic analysis experiments. Finally, the response characteristics are analyzed by the finite element method and the stress wave theory. The results show that with the change of impact overload, the axial direction of the 93W spherical component changes linearly with the radial deformation, and the axial strain increases with the increase of the impact overload. At the same time, along the radial direction from the center of the sphere, the micrograin distribution of 93W appears densely packed and sparsely separated, and the grain density is uniformly changed between dense area and sparse area, showing a ring-shaped “bright band” phenomenon between light and dark, and the width of the “bright band” is related to the size of the dense area of the grain; with the increase of the impact overload, the 93W alloy component first breaks at the central axis and the radial maximum position, and the fracture mode changes from the crystal fracture to the transgranular fracture tendency, and the two fracture forms eventually coexist.

The objective of this study is to propose a heuristic model of energy propagation due to an anomaly; electromagnetic (EM) field penetration into a continuously covered conducting enclosure (Faraday shield) from an external radio frequency source, violating the accepted model in the EM field theory. In this study, at an arbitrarily selected frequency, range of 26.965–1,800 MHz, of an external frequency source, an EM field inside the conducting enclosure was observed, contrary to expectations, which was followed by a systematic examination. Although no induced voltage could be expected inside the enclosure according to the classical theory, the experiment revealed a clear induced voltage inside, an attenuated induced voltage of −18.0 to −1.0 dB (for the range of frequencies 26.965–1,800 MHz) was observed. Hence, these results apparently contradict the established notion that an EM field cannot penetrate a Faraday shield. Rationalizing these observations and the results of the investigation leads to an alternative model to the existing models of energy propagation in free space. In this model, novel quantities named “I-Spin-energy” and “I-Spin-energy field” are defined to replace the concept of electric and magnetic fields in the classical EM theory. The proposed I-Spin-energy model is capable of explaining the unexpected presence of the EM field inside the Faraday shield as well as the induction of an alternating current in a conductor placed inside a Faraday shield along with other existing observations in physics such as those in famous Young’s double-slit experiment on interference of light, which provided the basis for the wave theory.

In this study, we propose a new design for a microchannel filter. The closed indoor environments with which we interact daily are sources of diseases for the respiratory system of human beings. Recommendations for the design of microchannel filters for indoor air purification are proposed, implementing low-cost microequipment technology (MET) for the manufacture of the elements that constitute a microfiltration system. For the microchannel filter production, we proposed to use MET, which is a miniaturization technology and can reduce manufacturing costs. The microchannel filter was 3.75 cm in radius with a thickness of 3 mm. It had a triangular profile and a helical trajectory. It was designed, manufactured, and tested for two profile dimensions. The main purpose was to reduce the pressure drop of the air flow through the filter. We described the air flow simulation for the microchannel filter using SolidWorks. A prototype microchannel filter was constructed, which underwent manufacturing tests. It is possible to clean the microchannel using water flow, which allows us to maintain the filtration quality within an optimum range of contaminant removal.

Garay-Avendaño and Zamboni-Rached defined two classes of axisymmetric solutions of the free Maxwell equations. We prove that the linear combinations of these two classes of solutions cover all totally propagating time-harmonic axisymmetric free Maxwell fields – and hence, by summation on frequencies, all propagating axisymmetric free Maxwell fields. It provides an explicit representation for these fields. This will be important, e.g., to have the interstellar radiation field in a disc galaxy modeled as an exact solution of the free Maxwell equations.

In this article, the linear dynamic analysis of AC generators modeled as RLC circuits with periodically time-varying inductances via Floquet’s theory is considered. Necessary conditions for the dynamic stability are derived. The harmonic balance method is employed to predict the transition curves and stability domains. An approximate expression for the Floquet form of solution is constructed using Whittaker’s method in the neighborhood of transition curves. Numerical verifications for the obtained theoretical results are considered. In accordance with the experimental results, a satisfactory agreement is relatively achieved with the closed experimental literature of the problem.

In order to solve the problem of large error of subpixel matching and poor filtering effect in traditional methods, a subpixel matching method based on geographical information is proposed. First, the image quality of the remote sensing image is enhanced by the image enhancement method based on light energy allocation. Then, the boundary geographic information is extracted by the improved thresholding segmentation algorithm based on histogram exponential convex hull for the enhanced remote sensing image of ground features. Based on the extracted geographic information, by matching the boundary image with the function measurement method, the center coordinates of the image block corresponding to the actual measurement map and the reference submap which achieve the best matching are obtained. According to the corresponding geometric transformation relationship between the measured image and the reference image, the subpixel matching of the measured remote sensing image and the reference image can be carried out under the least-square-error criterion. The experimental results show that the enhancement performance and noise filtering performance of the proposed method are better than those of the same type of method, the matching residual is very small, the matching accuracy is high, and the application value is significant.

Using the apparent magnitude-limited Main galaxy sample of the Sloan Digital Sky Survey Data Release 10, we examine the K-band luminosity–density relation at fixed parameters or for different galaxy families. It is found that the limiting or fixing galaxy properties, such as galaxy morphology, stellar mass, and color, exert substantial influence on the environmental dependence of the K-band luminosity of galaxies, which suggests that the K-band luminosity–density relation is likely attributable to the relation between these galaxy properties and density.

According to the design requirements of high-temperature combustion chamber, an advanced shaped hole structure was designed for film cooling. Numerical method was applied in this study to investigate the flow and heat transfer characteristics of shaped holes and compared with those of cylindrical holes. The influence of the forward expansion angle of shaped holes on the flow and heat transfer was studied. The results show that compared to cylindrical holes, the diffused structure of shaped holes decreases the momentum of jet flow, improves the adhesion characteristics of the cooling air film, increases the diffusion of the coolant air outflow and improves the cooling efficiency between adjacent columns of holes in the lateral direction. When the forward expansion angle increases, the expansion section induced the flow vortex, which reduces the radial velocity of coolant flow and enhances the diffusion of cooling air film both in streamwise and spanwise directions. However, as the forward expansion angle increases further, the scale of vortex inside the shaped hole grows. Too large vortex inside the shaped hole increases the coolant eject angle, which weakens the film covering effect. Additionally, the shaped hole results in an increase in lateral spreading and enhances the cooling effect between adjacent columns of the film hole. The enhancement of the film cooling characteristics is due to the change in the shape of the film hole, resulting in the enhancement of the flow vortex, which induces complicated secondary flow.

In general, the seasonal characteristics of small hydropower (SHP) especially the power transmission during the summer flood season would lead to the steady overvoltage of the distribution network. In order to suppress this steady overvoltage, a strategy for coordinated cooperation between generator phase-in operation and shunt reactors which can be called cooperative control is proposed. The distribution network of SHP stations connected to the 35 kV Bantao substation in southern Shaanxi is taken as an example to study the mechanism of overvoltage after the SHP is connected to the grid. A distribution network model with SHP units is established. Based on the model, the effect of separately installing shunt reactors on the node voltage is studied in the case of generator lag phase operation and the influence of the operation mode of SHP unit on the node voltage is also analyzed separately. Finally, the improvement measures of cooperative control between the generator phase-in operation and the parallel reactors are analyzed by simulation. Results are presented to verify the improvement measures that can effectively restrain the overvoltage of the distribution network in the SHP area.

The effect of center of mass (CoM) trajectory on stable walking of biped robot was studied in this study. The method of predictive control by controlling CoM trajectory to generate stable walking patterns was discussed, which simulated the principle of adjusting center of gravity in advance during human walking to adapt to the change of road conditions. As for uncertainty of robot modeling and the influence of environment, adding variable zero moment point for variable predictive control system can achieve self-adaptive adjustment of CoM trajectory to generate stable walking patterns. The simulation experiment results indicated that walking stability of biped robot was sensitive to the change of CoM trajectory. As long as CoM trajectory was adjusted well, stable walking of biped robot can be controlled even in the presence of disturbances. It is proved that the method of predictive control by controlling CoM motion to generate stable walking pattern is consistent with reality.

In view that the traditional dynamic recrystallization (DRX) model cannot effectively predict the DRX process in the hot deformation process of sheet metal, DRX behavior modeling and simulation of q890 steel plate based on the plane strain compression test are designed. The plane strain thermal simulation tests were performed at 1,223–1,373 K and the strain rates of 1–50 −1 on Gleeble-3500 thermal–mechanical simulator. The flow stress curves were well smoothed. The stress–strain data were investigated for the analysis of the dynamic recrystallization in the process of thermal deformation. The activation energy of DRX was calculated as Q = 394.53 kJ/mol by the simulation data. The equation of peak strain was developed with the flow stress data by the Zener–Hollomon parameter. The DRX transformation fraction of Q890 steel was studied, and the DRX kinetics equation was developed by the Avrami equation. The experimental data are in good agreement with the calculated values, which proves the reliability of the DRX model and can be widely used in real life.

This article proposes a thrust equation model of two-degree-of-freedom oscillatory actuator considering its edge effect. The proposed thrust equation model clarifies that asymmetric permanent magnet flux linkage and inductance characteristics cause undesirable magnetic thrust and reluctance thrust, respectively.

In this work, we theoretically analyzed the main factors affecting performance of multistage energy recovery hydraulic turbine (MERHT), and found that the arc radius ( r ) of the edge at the outlet section of the runner guide vane is the determining factor of the hydraulic efficiency of hydraulic turbines. To further improve the performance of the MERHT, a numerical model is then proposed to optimize the arc radius. The MERHT-type DCSGT250-175 × 9 was taken in the simulation. The hydraulic efficiency η h and the corresponding distributions of pressure and velocity were numerically studied with four different values of r ranging from 133.5 to 138 mm. It is found that the flow state and the flow field distribution were the best when r equals to 134 mm. With the optimum r , the external diameter of the runner guide vane ( D ) was further adjusted, which can lead to 3.9% increase of average efficiency according to the simulation results.

The purpose of this article is to present a generic reluctance network modeling tool dedicated to the modeling of electrical machines. This tool is used for the study of permanent magnet machines. The focus will be on the modeling methodology and software implementation. More precisely, the aspects related to genericity will be discussed. In order to validate the developed tool, the simulation of a 12 slot/10 pole flux-switching permanent magnet machine is conducted, and the results obtained from this generic framework are compared to the corresponding finite element analysis.

We applied an optimal control algorithm to an ultra-cold atomic system for constructing an atomic Sagnac interferometer in a ring trap. We constructed a ring potential on an atom chip by using an RF-dressed potential. A field gradient along the radial direction in a ring trap known as the dimple-ring trap is generated by using an additional RF field. The position of the dimple is moved by changing the phase of the RF field [1]. For Sagnac interferometers, we suggest transferring Bose–Einstein condensates to a dimple-ring trap and shaking the dimple potential to excite atoms to the vibrational-excited state of the dimple-ring potential. The optimal control theory is used to find a way to shake the dimple-ring trap for an excitation. After excitation, atoms are released from the dimple-ring trap to a ring trap by adiabatically turning off the additional RF field, and this constructs a Sagnac interferometer when opposite momentum components are overlapped. We also describe the simulation to construct the interferometer.

Alteration in the environmental conditions will cause a reversed reaction between o/w emulsion and w/o emulsion that has similar advantages of different liquids form on the reversible invert emulsion. The reversible phase inversion of the emulsion has a benefit of dealing with drilling cutting, so the reversible invert emulsion also can be thought used as a drilling fluid. The phase inversion from w/o emulsion to o/w emulsion can be divided into three stages. They are w/o emulsion, w/o/w emulsion, and o/w emulsion. In the w/o emulsion stage, the structure appeared among water droplets when the percentage of the HCl solution (5%) was less than 0.375%. In the w/o/w emulsion stage, the structure among water droplets existed at the beginning of this stage; however, the internal phase and the external phase can interchange their positions during the process. In the third stage, the structures among droplets of the emulsion would be broken and the degree of the dispersion of the oil droplet in the emulsion would increase. The changes in the microstructure, conductivity, electrical stability, standing stability, and the viscosity of the emulsion, which have edified among droplets in the process from w/o emulsion to o/w emulsion, were studied. The result of the microstructure microscopic observation agrees with the result of the electrical stability and viscosity experiments. Moreover, the internal phase and the external phase can interchange positions during the process.

Due to the poor mechanical properties of traditional simulation models of the organic light-emitting device (OLED) bending area, this article puts forward a finite element model of 3D bending simulation of the OLED bending area. During the model construction, it is necessary to determine the viscoelastic and hyperelastic mechanical properties, respectively. In order to accurately obtain the stress changes of material deformation during the hyperelasticity determination, a uniaxial tensile test and a shear test were used to obtain data and thus to characterize the hyperelastic properties. In order to measure the viscoelasticity, a stress relaxation test was used to draw the stress relaxation curve, so as to characterize the viscoelastic properties. Then, the plane or axisymmetric stress–strain analysis was achieved, and the material parameters of the 3D model of the OLED bending area were obtained. Finally, the 3D model was applied to the 3D bending of the OLED bending area. Combined with the axisymmetric finite element analysis method, the 3D bending simulation finite element model of the OLED bending area was constructed by dividing the finite element mesh. Experimental results show that the mechanical properties of the proposed model are better than those of traditional OLED bending simulation models. Meanwhile, the proposed model has stronger application advantages.

In order to solve the problem that the long cable variable voltage and variable frequency (VVVF) system does not adopt an effective capacitor voltage sharing control method, resulting in a poor effect of resonance overvoltage control, the resonance overvoltage control algorithm of the long cable VVVF system based on discrete mathematics is studied. First, the long cable frequency conversion drive system is established. In order to ensure voltage loss in the range of motor requirements, a frequency converter–cable–motor (ICM) system connection mode is used to maintain the system operation. Based on the research of the capacitor voltage balance control strategy of a long cable frequency conversion drive system, the discrete mathematical model of the AC side of the ICM system is established by using this control strategy. The improved constant active power controller is obtained by establishing the mathematical model, and the resonant overvoltage in a long cable frequency conversion drive is realized by using the constant active power controller. The experimental results show that the algorithm can effectively control the resonance overvoltage phenomenon in the long cable frequency control system, and the control accuracy is over 97%. It has good performance and can be applied in practice.

Nanosheets are two-dimensional polymeric materials, which are among the most active areas of investigation of chemistry and physics. Many diverse physicochemical properties of compounds are closely related to their underlying molecular topological descriptors. Thus, topological indices are fascinating beginning points to any statistical approach for attaining quantitative structure–activity (QSAR) and quantitative structure–property (QSPR) relationship studies. Irregularity measures are generally used for quantitative characterization of the topological structure of non-regular graphs. In various applications and problems in material engineering and chemistry, it is valuable to be well-informed of the irregularity of a molecular structure. Furthermore, the estimation of the irregularity of graphs is helpful for not only QSAR/QSPR studies but also different physical and chemical properties, including boiling and melting points, enthalpy of vaporization, entropy, toxicity, and resistance. In this article, we compute the irregularity measures of graphene nanosheet, H -naphtalenic nanosheet, SiO 2 {\text{SiO}}_{2} nanosheet, and the nanosheet covered by C 3 {C}_{3} and C 6 {C}_{6} .

To a large extent, the load balancing algorithm affects the clustering performance of the computer. This paper illustrated the common load balancing algorithms and elaborated on the advantages and drawbacks of such algorithms. In addition, this paper provides a kind of balancing algorithm generated on the basis of the load prediction. Due to the dynamic exponential smoothing model, such an algorithm helps obtain the corresponding smoothing coefficient with the server node load time series of current phrase and allows researchers to make prediction with the load value at the next moment of this node. Subsequently, the dispatcher makes the scheduling with the serve request of users according to the load predicted value. OPNET Internet simulated software is applied to the test, and we may conclude from the results that the application of such an algorithm acquires a higher load balancing efficiency and better load balancing effect.

In order to obtain the influence of different seismic motion input modes on the performance of isolated structures with different seismic measures, the two aspects from near-fault seismic motion velocity pulse input and different dimension seismic motion input modes are studied. The finite element model of traditional seismic and base isolation frame structure with different aspect ratios is established. The actual near-seismic strong earthquake record with forward directional effect and slipping speed pulse is used as the input method of structural seismic motion to carry out nonlinear dynamics. The different dimensional seismic motion input method is selected as the quantitative, the tensile–compression stiffness ratio is the variable, and the time-history analysis of the isolation performance of a high-rise isolated structure is carried out. The experimental results show that for structures with an aspect ratio H/B of 1, 2, 3, and 4, the smaller the aspect ratio is, the better the damping effect is; the different dimensional vibration input has less isolation performance for the isolation bearing. From small to large, it is: one-dimensional vibration input, two-dimensional vibration input, three-dimensional vibration input.

Arterial tissue delamination, manifested as the fracture failure between arterial layers, is an important process of the atherosclerotic plaque rupture, leading to potential life-threatening clinical consequences. Numerous models have been used to characterize the arterial tissue delamination fracture failure. However, only a few have investigated the effect of cohesive zone model (CZM) shapes on predicting the delamination behavior of the arterial wall. In this study, four types of CZMs (triangular, trapezoidal, linear–exponential, and exponential–linear) were investigated to compare their prediction of the arterial wall fracture failure. The Holzapfel–Gasser–Ogden (HGO) model was adopted for modeling the mechanical behavior of the aortic bulk material. The CZMs optimized during the comparison of the aortic media delamination simulations were also used to perform the comparative study of the mouse plaque delamination and human fibrous cap delamination. The results show that: (1) the numerical predicted the relationships of force–displacement in the delamination behaviors based on the triangular, trapezoidal, linear–exponential, and exponential–linear CZMs match well with the experimental measurements. (2) The traction–separation relationship results simulated by the four types of CZMs could react well as the corresponding CZM shapes. (3) The predicted load–load point displacement curves using the triangular and exponential–linear CZMs are in good agreement with the experimental data, relative to the other two shapes of CZMs. All these provide a new method combined with the factor of shape in the cohesive models to simulate the crack propagation behaviors and can capture the arterial tissue failure response well.

The surface cleanliness of photovoltaic (PV) panel has an important impact on the efficiency of power generation. The excessive mass of cross arm has always affected the use of cleaning device. Based on the power correlation analysis, the dynamic characteristics of cross arm lightweight of PV panel cleaning device in the power station are proposed. Using the theory of information fusion to weigh it as a comprehensive influence factor, the power prediction value of the model output is transmitted to the cleaning device in real time: design the cleaning device of PV panel and optimize the topology of the mechanical cross arm. The experimental results show that the PV power is related to many meteorological factors, and the lightweight design of the cross arm is more conducive to the natural frequency and mode shape analysis of each mode of the cross arm structure.

This article gives an account of a theoretical research subdivided into three parts. The first stage recalls the theorem of large numbers and the theorem a single number which demonstrate how the frequentist and the subjective models of probability can be used according to distinct assumptions. Based on these achievements, the second stage describes the temporal evolution of the random outcome (this article distinguishes the outcome from the random event or phenomenon that produces it). It is proved that the outcome of a single unpredictable event switches from the indeterministic to the deterministic state when the event winds up. The third stage means to show how the theoretical results apply to physical situations.

This study reveals the characteristics of chemical reaction on Marangoni mixed convective stream towards a penetrable Riga surface. The heat and mass phenomena are analysed within the sight of Dufour and Soret impacts. The administering partial differential equations system is converted into three nonlinear ordinary differential equations utilizing appropriately adjusted transformations. The resultant system of highly nonlinear equations is analytically solved by invoking the homotopy analysis method. Thereafter, the convergence of series solutions is discussed. The impact of appropriate parameters on various flow fields is thoroughly explained with the help of graphs and tables. The wall drag coefficient and relevant flux rates are arranged and discussed for dimensionless parameters. The outcomes show that the stronger Dufour effect of liquid causes a notable incremental variation in heat and mass flux, whereas an opposite trend is noted in the heat flux rate for the Soret effect. However, the mass flux is still found increasing for the stronger Soret effect.

Complementary metal oxide semiconductor (CMOS) cameras have been used to detect ionizing radiation when shaded from light or under the condition of static scenes. We propose a novel idea for simultaneous measurement of ionizing radiation and heart rate (HR) by using a smartphone with its CMOS camera lens covered by a finger in one measurement. Verified experiments were conducted: videos were recorded using a Xiaomi8 smartphone when the camera lens was covered by a finger and a light-tight tape for controlled experiment, with a ∼33 mCi 99m Tc liquid radioactive source at six different distances (from 20 to 70 cm, step size 10 cm) from the camera. The exact HRs were measured using an oximeter at the same time. Image processing algorithm is proposed to extract radiation events and HR in the same videos. Results show that: (1) frame numbers containing radiation-related bright spots in two experiments have a linear relationship, and they are inversely proportional to the square of the distance between the camera and radiation source; (2) the HR difference between the video processing and the oximeter result is less than 2 beats per minute. In conclusion, it verifies that the proposed method is available to detect ionizing radiation and measure HR simultaneously with smartphone camera lens covered by a finger. We have been working on the development of an Android phone application based on the algorithms.

Solving nonlinear evolution equations is an important issue in the mathematical and physical sciences. Therefore, traditional methods, such as the method of characteristics, are used to solve nonlinear partial differential equations. A general method for determining analytical solutions for partial differential equations has not been found among traditional methods. Due to the development of symbolic computational techniques many alternative methods, such as hyperbolic tangent function methods, have been introduced in the last 50 years. Although all of them were introduced as a new method, some of them are similar to each other. In this study, we examine the following four important methods intensively used in the literature: the tanh–coth method, the modified Kudryashov method, the F-expansion method and the generalized Riccati equation mapping method. The similarities of these methods attracted our attention, and we give a link between the methods and a system of projective Riccati equations. It is possible to derive new solution methods for nonlinear evolution equations by using this connection.

In view of the problem of large earthquake displacement in the use of the original concrete engineering shear wall reinforcement method, the energy dissipation and damping structure is used to design the energy dissipation and damping structure reinforcement method in the concrete engineering shear wall. According to the design process of the set method, the anti-vibration coefficient of the concrete shear wall is tested. The energy dissipation structure is used to construct a shear damping wall, and the damper is added to the original shear wall. The concrete shear wall is strengthened by sticking steel technology. So far, the design of shear wall reinforcement method based on the energy dissipation structure has been completed. Compared with the original method, the displacement distance of this method is lower than that of the original method. In conclusion, the effect of shear wall reinforcement method based on the energy dissipation structure is better than that of the original method.

In process industry control, process data is critical for both control and fault diagnosis. Timely detection of outliers and mutation point in process data can quickly adjust control parameters or discover potential failures throughout the system. Aiming at the shortcomings of the traditional mutation point detection method, such as the detection time delay and not being suitable for the process industrial data that mixed outliers, this paper proposes a mutation point and outliers detection method that is suitable for the grinding grading system using the wavelet method to analyze the “Efficient Scoring Vector.” In this algorithm, to distinguish between outliers and mutation points in the detection process, we propose a detection framework based on the relationship between Lipschitz index and wavelet coefficients. Under this framework, the detection algorithm proposed in this paper can detect outliers and mutation points simultaneously. The advantage of this is that the accuracy of the mutation point detection is not affected by the outliers. This means that the method can process grinding grading system process data containing outliers and mutation points under actual operating conditions and is more suitable for practical applications. Finally, the effectiveness and practicability of the proposed detection method are proved by simulation results.

Traditional testing algorithm based on pattern matching is impossible to effectively analyze the heat transfer performance of heat pipes filled with different concentrations of nanofluids, so the testing algorithm for heat transfer performance of a nanofluidic heat pipe based on neural network is proposed. Nanofluids are obtained by weighing, preparing, stirring, standing and shaking using dichotomy. Based on this, the heat transfer performance analysis model of the nanofluidic heat pipe based on artificial neural network is constructed, which is applied to the analysis of heat transfer performance of nanofluidic heat pipes to achieve accurate analysis. The experimental results show that the proposed algorithm can effectively analyze the heat transfer performance of heat pipes under different concentrations of nanofluids, and the heat transfer performance of heat pipes is best when the volume fraction of nanofluids is 0.15%.

Sardar subequation approach, which is one of the strong methods for solving nonlinear evolution equations, is applied to conformable resonant Schrödinger’s equation. In this technique, if we choose the special values of parameters, then we can acquire the travelling wave solutions. We conclude that these solutions are the solutions obtained by the first integral method, the trial equation method, and the functional variable method. Several new traveling wave solutions are obtained including generalized hyperbolic and trigonometric functions. The new derivation is of conformable derivation introduced by Atangana recently. Solutions are illustrated with some figures.

The present study aims to design a second-order nonlinear Lane–Emden coupled functional differential model and numerically investigate by using the famous spectral collocation method. For validation of the newly designed model, three dissimilar variants have been considered and formulated numerically by applying a famous spectral collocation method. Moreover, a comparison of the obtained results with the exact/true results endorses the effectiveness and competency of the newly designed model, as well as the present technique.

Due to the high redundancy of ultra-wideband (UWB) radio frequency (RF) signal receiving channel and the channel’s non-rotation invariance, the signal-to-noise ratio (SNR) of signal transmission is increased. In order to solve this problem, a circularly symmetric algorithm for the UWB RF signal receiving channel based on spectrum compression cannot effectively reduce the redundancy of UWB RF signal receiving channel; the channel does not have rotation invariance; and the effect of noise reduction is poor. A circularly symmetric algorithm for the UWB RF signal receiving channel based on noise cancellation is proposed, and a noise cancellation structure at the input stage of the receiving channel is constructed to ensure channel noise cancellation and reduce noise in the channel. On this basis, five power zones are used to reasonably select RF devices, receive and downconvert UWB RF signal receiving channel, and convert the received UWB RF signal channel into circular symmetric Gabor transform to reduce redundancy and ensure the strict rotation invariance of the channel. The experimental results show that the proposed algorithm guarantees the quality of the signal and the stable transmission of the signal information. The SNR is 3.8672, and the root mean square error is 0.4078. The third-order cross-modulation coefficient of the signal receiving channel controlled by the algorithm meets the requirements of the index and the mirror frequency rejection requirement of the index.

The periodic four-layered model of the pure Cu(111) surface has been considered, and the effect of doping with palladium on CH 4 dissociation has been investigated. The most stable adsorption geometries of CH x species ( x = 1–4) and H atom on the PdCu(111) and pure Cu(111) surfaces have been obtained. Their computed adsorption energy results on the pure Cu(111) surface have been compared with the previously reported studies. Then, transition state geometries of CH 4 dehydrogenation steps on both surfaces were calculated by the climbing image nudged elastic band method. Finally, the relative energy diagram for CH 4 complete dehydrogenation has been represented. The results show that the PdCu(111) surface is more favorable than the Cu(111) surface in terms of the activation energies. The addition of Pd atoms to the Cu(111) surface significantly improves the catalytic activity. This knowledge can enable an efficient catalyst design at a lower cost using different strategies.

The purpose of this article is to construct some novel exact travelling and solitary wave solutions of the time fractional (2 + 1) dimensional Konopelchenko–Dubrovsky equation, and two different forms of integration schemes have been utilized in this context. As a result, a variety of bright and dark solitons, kink- and antikink-type solitons, hyperbolic functions, trigonometric functions, elliptic functions, periodic solitary wave solutions and travelling wave solutions are obtained, and the sufficient conditions for the existence of solution are also discussed. Moreover, some of the obtained solutions are illustrated as two- and three-dimensional graphical images by using computational software Mathematica. These types of solutions have a wide range of applications in applied sciences and mathematical physics. The proposed methods are very useful for solving nonlinear partial differential equations arising in physical science and engineering.

In this work, we perform Lie group analysis on a fifth-order integrable nonlinear partial differential equation, which was recently introduced in the literature and contains two dispersive terms. We determine a one-parameter group of transformations, an optimal system of group invariant solutions, and derive the corresponding analytic solutions. Topological kink, periodic and power series solutions are obtained. The existence of a variational principle for the underlying equation is proven using Helmholtz conditions and, thereafter, both local and nonlocal conserved quantities are obtained by utilising Noether’s theorem and a homotopy integral approach.

Horizontal concave slope structure is a common mining structure. It is the basis of mining safety to grasp the reasonable mining distance of horizontal concave slope. Therefore, based on variable scale chaotic algorithm, the reasonable mining distance of horizontal concave slope is studied. The safety factor is used to describe the reliability of the slope. When the slope is in a reliable state, it is a reasonable mining distance. Based on the Warehouse–Mohr strength theory, the four key parameters of rock cohesion and internal friction angle of horizontal concave slope and major and minor stress of element nodes are considered. The similarity of mining safety factor of horizontal concave slope is measured and the objective function is constructed. The target is searched based on variable-scale chaotic algorithm. The output result is the optimal solution of reasonable mining distance for horizontal concave slope. The experimental study shows that the reasonable mining distance of horizontal concave slope can be obtained effectively based on variable scale chaotic algorithm, and the slope height and slope angle are inversely proportional to the mining reliability of horizontal concave slope.

Traditionally, three-dimensional model is used to classify and recognize multi-target optical remote sensing image information, which can only identify a specific class of targets, and has certain limitations. A mathematical model of multi-target optical remote sensing image information classification and recognition is designed, and a local adaptive threshold segmentation algorithm is used to segment multi-target optical remote sensing image to reduce the gray level between images and improve the accuracy of feature extraction. Remote sensing image information is multi-feature, and multi-target optical remote sensing image information is identified by chaotic time series analysis method. The experimental results show that the proposed model can effectively classify and recognize multi-target optical remote sensing image information. The average recognition rate is more than 95%, the maximum robustness is 0.45, the recognition speed is 98%, and the maximum time-consuming average is only 14.30 s. It has high recognition rate, robustness, and recognition efficiency.

A quasi-static tensile test was performed on a 1.4 mm-thick TRIP780 steel strip with welding points. An MTS810 material test machine was used in the test, and a Split Hopkinson tension bar device was used in performing impact stretch loading at different strain rates. The dynamic tensile stress–strain curve of the spot welding material with different strain rates was obtained through the finely designed Hopkinson rod test, and the strain rate dependence of a TRIP780 steel spot welding material was discussed. According to the dynamic constitutive equation of the TRIP780 steel spot welding material, the test results were numerically simulated, the constitutive description and test curves were compared, and the simulation results and test results were discussed and analyzed. The fractures of the test recovery specimen were scanned with the scanning electron microscope, and the fracture mechanism of the TRIP780 steel spot welding material was explored by observing the fractures. The surfaces of the fractures surface showed obvious cleavage river patterns, and the evolution process of microcracks was determined and used in characterizing brittle fractures in specimen spot welding sample subjected to dynamic stretch loading.

This article addresses the effects of thermal radiation, stratification, and Joule heating for the flow of magnetohydrodynamics Sutterby nanofluid past over a stretching cylinder. The transport phenomenon of heat and mass are modeled under temperature-dependent thermal conductivity and diffusion coefficients, respectively. Moreover, traditional Fourier and Fick’s laws have been implemented in thermal and mass transport expressions. The governing model that consists of a set of coupled partial differential equations is converted into system of nonlinear coupled ordinary differential equations via suitable similarity transformations. The resulting set of expressions is analytically treated through an optimal homotopy scheme. The effects of different dimensionless flow parameters on the velocity, temperature, and concentration fields are illustrated through graphs. The patterns of skin friction coefficient, local Nusselt, and Sherwood numbers are examined via bar charts. The major outcome of the proposed study is that variable thermal conductivity decays the temperature and radiation raises the temperature of the system. Stratification parameters show the reverse behavior for temperature and concentration boundary layers. Shear rate-dependent rheology in view of Sutterby liquid has the ability to reduce the flow of fluid. Therefore, the ability of flow in rheology of Sutterby liquid becomes reduced. Consequently, layer of momentum boundary has increased with respect to parameter of Sutterby liquid.

Pennes’ bioheat equation is the most widely used thermal model for studying heat transfer in biological systems exposed to radiofrequency energy. In their article, “Effect of Surface Cooling and Blood Flow on the Microwave Heating of Tissue,” Foster et al. published an analytical solution to the one-dimensional (1-D) problem, obtained using the Fourier transform. However, their article did not offer any details of the derivation. In this work, we revisit the 1-D problem and provide a comprehensive mathematical derivation of an analytical solution. Our result corrects an error in Foster’s solution which might be a typo in their article. Unlike Foster et al., we integrate the partial differential equation directly. The expression of solution has several apparent singularities for certain parameter values where the physical problem is not expected to be singular. We show that all these singularities are removable, and we derive alternative non-singular formulas. Finally, we extend our analysis to write out an analytical solution of the 1-D bioheat equation for the case of multiple electromagnetic heating pulses.

This research is mainly concerned with the characteristics of magnetohydrodynamics and Darcy–Forchheimer medium in nanofluid flow between two horizontal plates. A uniformly induced magnetic impact is involved at the direction normal to the lower plate. Darcy–Forchheimer medium is considered between the plates that allow the flow along horizontal axis with additional effects of porosity and friction. The features of Brownian diffusive motion and thermophoresis are disclosed. Governing problems are transformed into nonlinear ordinary problems using appropriate transformations. Numerical Runge–Kutta procedure is applied using MATLAB to solve the problems and acquire the data for velocity field, thermal distribution, and concentration distribution. Results have been plotted graphically. The outcomes indicate that higher viscosity results in decline in fluid flow. Thermal profile receives a decline for larger viscosity parameter; however, Brownian diffusion and thermophoresis appeared as enhancing factors for the said profile. Numerical data indicate that heat flux reduces for viscosity parameter. However, enhancement is observed in skin-friction for elevated values of porosity factor. Data of this paper are practically helpful in industrial and engineering applications of nanofluids.

Molecular topology is a key to determine the physiochemical aspects of the molecular structure. To determine the degree of irregularity of a certain molecular structure or a network has been a key source of interest for the molecular topologists as it provides an insight of the key features that are used to guess the properties of the structures. In this article, we are interested in formulating closed forms of irregularity measures of some popular benzenoid systems, namely, zigzag, rhombic, and honeycomb benzenoid systems. We also compared our results graphically and concluded that benzenoid system among above is more asymmetric than the others.

Wireless sensor networks (WSNs) have great application potential in partition parameter observation, such as forest fire detection. Due to the limited battery capacity of sensor nodes, how to reduce energy consumption is an important technical challenge. In this paper, we propose an energy efficient routing algorithm of adaptive double cluster head (CH) based on nonuniform partition for WSN. Firstly, according to the distance information from the base station (BS) to every sensor node, the network is divided into several uneven partitions. Secondly, CH is selected for each partition as the primary cluster head (PCH). Because of the cluster-level routing, the CHs close to the BS need to forward more data than the CHs in other areas, which consumes more energy. Therefore, an adaptive double CH method can be used to generate a secondary cluster head (SCH) in the cluster near the BS according to the parameters. Finally, the PCH is responsible for data collection, data integration, and data transmission. while the SCH is in charge of data routing. Simulation results show that the proposed algorithm can reduce the energy consumption and extend the life of the WSNs, compared with LEACH protocol and the HEED protocol.

In this paper, we obtain a generalization of the Gronwall’s inequality to cover the study of porous elastic media considering their internal state variables. Based on some estimations obtained in three auxiliary results, we use this form of the Gronwall’s inequality to prove the uniqueness of solution for the mixed initial-boundary value problem considered in this context. Thus, we can conclude that even if we take into account the internal variables, this fact does not affect the uniqueness result regarding the solution of the mixed initial-boundary value problem in this context.

Pickering emulsions have attracted extensive attention due to their good properties including easy to manufacture, high stability, and superparamagnetic response. To improve the emulsifying transportation of crude oil, a Pickering emulsion of crude oil and water stabilized by Fe 3 O 4 nanoparticles was prepared and its rheological properties were tested in this research. It was found that the particle size of dispersion droplet polymerization group in stable crude oil Pickering emulsion is negatively correlated with solid content and water content, and the equilibrium apparent viscosity μ ap {\mu }_{\text{ap}} of emulsion follows the power law fluid equation. Besides, this kind of Pickering emulsion has higher elasticity of interface membrane, which means by adding functional particles, it obtains good dynamic stability, and thus, has a great application property in crude oil industry.

Recent studies have highlighted the statistical relevance and applicability of trigonometric distributions for the modeling of various phenomena. This paper contributes to the subject by investigating a new trigonometric family of distributions defined from the alliance of the families known as sine-G and Topp-Leone generated (TL-G), inspiring the name of sine TL-G family. The characteristics of this new family are studied through analytical, graphical and numerical approaches. Stochastic ordering and equivalence results, determination of the mode(s), some expansions of distributional functions, expressions of the quantile function and moments and basics on order statistics are discussed. In addition, we emphasize the fact that the sine TL-G family is able to generate original, simple and pliant trigonometric models for statistical purposes, beyond the capacity of the former sine-G models and other top models of the literature. This fact is revealed with the special three-parameter sine TL-G model based on the inverse Lomax model, through an efficient parametric estimation and the adjustment of two data sets of interest.

Among the many techniques for obtaining heat and electricity, solar thermal collectors, photovoltaic (PV) technology and PV/thermal (PV/T) technology have a very important place. The PV/T collectors enable the simultaneous conversion of solar radiation into thermal and electrical energy in a single device, with better space utilization and cost efficiency during construction. Specially designed PV/T collectors can replace the outer walls or roof covers and can be widely used in private houses, flat complexes, hospitals, schools, tourist and other objects for water heating and electrical energy generation. Due to their great application potential, hybrid collectors have been the subject of very intensive scientific research and technical development for many years. In this review article, the focus is on the research, development and application of the PV/T water systems in the last 10 years. The main task of researchers and manufacturers is to increase the efficiency of PV modules and thermal absorbers, using new materials and design types as well as their proper integration into the PV/T collector. It is also necessary to reduce the cost of these systems and make them more competitive in the market. In addition, the importance of PV/T systems is in providing energy in clean and environmentally friendly ways.

Mass transfer between the phases is a cornerstone of many technological processes and presents a topic whose understanding and modelling is of high importance. For instance, absorption of gases in liquid droplets is an underlying phenomenon for the desulfurization of flue gases in wet scrubbers. Wet scrubbing is an efficient cleaning method where the liquid is sprayed in a stream of rising gases, removing pollutants due to the concentration difference between the gas phase and droplets. A model for absorption in water droplets has been developed to describe the complex physical and chemical interactions during the exposure to flue gases. The main factors affecting the absorption are the mass transfer of pollutants through the gas–droplet interface and the aqueous phase chemistry in a droplet. The mass transfer coefficient, which has been modeled with several approaches, is the most significant parameter regulating the absorption dynamic into the droplet, while the in-droplet chemistry controls the maximum quantity of dissolved pollutants. Dissociation of sulfur dioxide and the chemical reactions in seawater have been described by the equilibrium reactions. Afterward, the influence of the mass transfer coefficient has been investigated, and the model has been validated against the literature data on a single droplet scale. Obtained results are comparable with the experimental measurements and indicate the applicability of the model for the design and development of industrial scrubbers.

In this article, lattice Boltzmann method (LBM) is used to simulate the multi-scale flow characteristics of the engine particulate filter at the pore scale and the representative elementary volume (REV) scale, respectively. Four kinds of random wall-pore structures are considered, which are circular random structure, square random structure, isotropic quartet structure generation set (QSGS), and anisotropic QSGS, with difference analysis done. In terms of the REV scale, the influence of different inlet flow velocities and wall permeabilities on the flow in single channel is analyzed. The result indicates that the internal seepage laws of random structures constructed in this article and single channel are in accordance with Darcy’s law. Circular random structure has better permeability than square random structure. Isotropic QSGS has better fluidity than anisotropic one. The flow in single channel is similar to Poiseuille flow. The flow lines in the channel are complicated and a large number of vortices appear at the ends of channel with high inlet flow rate. With the increase of inlet velocity, the static pressure in channel gradually increases along the axial direction as well as the seepage velocity. The temperature field in the channel becomes more uniform as the flow velocity increases, and the higher temperature distribution appears on the wall of the porous media.

Moisture variation in porous media depends mainly on the pore characteristics. This article used the micro-computed tomography (micro-CT) (a non-destructive imaging technique to generate a three-dimensional virtual model) and the Brooks–Corey model to deduce the moisture migration in sand. Relationship between capillary rise height and time ( h – t ) was achieved by numerical simulation in the capillary suction process, where the parameters fractal dimension, porosity, and air–water interfacial area were obtained by the micro-CT scanning. Meanwhile, experiments of capillary rise in sand column were performed using four different sizes washed sand, and the capillary heights at different times were recorded. Results show that the capillary suction is decided by the aperture size and phase morphology simultaneously, and particle size has obvious effect on capillarity, and the wetting front lowers with the increase in grain size and the decrease in rising rate. Parameters air entry pressure and pore-size distribution index obtained by micro-CT scanning technology and empirical formula are accurate. Method of combing micro-CT images and Brooks–Corey model can predict well the capillary suction of porous media. It is also proved that the capillary suction is decided by the aperture size and phase morphology simultaneously.

In this paper, the flow characteristics and energy equilibrium analysis of the effervescent atomization had been investigated theoretically and experimentally. The effect of the gas–liquid rate (GLR from 0.04 to 0.15) on the atomization stability was revealed. When the GLR was small, the atomization was unstable. The atomization was gradually stable with an increase in the GLR. The optimal atomization region can be obtained. The Sauter mean diameter (SMD) of the droplets was measured by the phase Doppler analyzer. The SMD decreases with an increase in the GLR. The energy equilibrium analysis was investigated for the swirl atomizer theoretically and experimentally. The results show that the energy dissipation terms are mainly compressed gas expansion, liquid viscosity dissipation, and resistance losses. However, the ratio of the spray kinetic energy and the surface tension energy to the total energy is small.

In order to investigate heat transfer characteristics of steam/nitrogen condensation inside horizontal enhanced condensation channels (HECCs), experiments have been performed, respectively, inside HECC and horizontal circular channel (HCC). HECC is formed by inserting different reinforcers into HCC including horizontal multi-start straight channels (HMSSCs) and horizontal spiral channels (HSCs). Effects of nitrogen mass fractions on average condensation heat transfer coefficients (CHTCs), average outlet condensate mass flowrates (CMFRs), and average steam-side pressure drops (SSPDs) are analyzed, respectively. The results indicate that HECC has better condensation performance than HCC under the same conditions, while average SSPDs of HECC will increase slightly. Then, HMSSC is compared against HCC, and enhancement factors of average CHTCs and average outlet CMFRs are about 1.45 and 1.12, respectively, while the enlargement factor of average SSPDs is about 1.16. Similarly, HSC is compared against HCC, and enhancement factors of average CHTCs and average outlet CMFRs are about 1.25 and 1.05, respectively, while the enlargement factor of average SSPDs is about 1.12.

A high accuracy of experimental correlations on the heat transfer and flow friction is always expected to calculate the unknown cases according to the limited experimental data from a heat exchanger experiment. However, certain errors will occur during the data processing by the traditional methods to obtain the experimental correlations for the heat transfer and friction. A dimensionless experimental correlation equation including angles is proposed to make the correlation have a wide range of applicability. Then, the artificial neural networks (ANNs) are used to predict the heat transfer and flow friction performances of a finned oval-tube heat exchanger under four different air inlet angles with limited experimental data. The comparison results of ANN prediction with experimental correlations show that the errors from the ANN prediction are smaller than those from the classical correlations. The data of the four air inlet angles fitted separately have higher precisions than those fitted together. It is demonstrated that the ANN approach is more useful than experimental correlations to predict the heat transfer and flow resistance characteristics for unknown cases of heat exchangers. The results can provide theoretical support for the application of the ANN used in the finned oval-tube heat exchanger performance prediction.

The thermal-hydraulic performance of a new parallel-flow shell and tube heat exchanger (STHX) with equilateral cross-sectioned wire coil (HCBetwc-STHX) is investigated in turbulent regime. Four different surrogate models are established to predict the thermal-hydraulic performance. Their merits and drawbacks are illustrated. The results show that the Nu etwc /Nu RRB and f etwc / f RRB are in the range of 1.1638–1.855 and 4.078–16.062, respectively. The precision of CFM is the lowest, whereas the precision of radial basis function + artificial neural network and Kriging model is the highest. A good balance can be achieved by response surface methodology between precision and cost. Finally, a general analysis procedure is presented for the predicting method of thermal-hydraulic performance of different STHX with relatively small cost and high precision.

Round rod baffle (RRB), plain plate baffle (PPB), wavy-shaped plate baffle (WSB) and polygonal-shaped plate baffle (PSB) are four commonly used baffles in parallel flow shell and tube heat exchangers (STHXs). Comparative study of these four different baffles are numerically carried out using different performance indicators including Nusselt number, friction factor, performance evaluation criterion, entropy generation ratio, and entransy dissipation ratio for flow in full turbulent regime. Heat transfer mechanism has also been discussed. Correlations for Nusselt number and friction factor are fitted and the cost estimation using Hall’s method is compared. It is found that the Nusselt number of STHX-PPB, STHX-WSB, and STHX-PSB increased by 20.9%, 15.2%, and 23.9% averagely compared with STHX-RRB, respectively. The friction factor can be increased on average by 142.0%, 154.5%, and 242.4%, respectively. However, the overall performance of them is only 90.1%, 84.4%, and 82.3% that of STHX-RRB, respectively. The sequence of entropy generation and entransy dissipation is STHX-RRB > STHX-WSB > STHX-PPB > STHX-PSB. The inlet Re and baffle distance have significant effects on different performance indicators while the baffle width does not. Finally, the results show that the STHX-PSB can reduce the total cost as it has better ability on heat enhancement.

The inflow uniformity before selective catalytic reduction (SCR) catalyst carrier is a major issue for DeNO x capability of diesel engine after-treatment. Through the construction of the numerical model and CFD simulation of six perforated plate variations with different structural and positional characteristics, the influence of perforated plates on the uniformity of the airflow velocity at the inlet of the SCR catalyst carrier was analyzed. Comparison of different perforated plate variations shows that the encircling flow is a major hindrance to achieve higher inflow uniformity. Enclosed flow passage can remove the encircling flow and increase inflow uniformity at the cost of increased pressure drop. Rational layout of the perforated plate can achieve uniformity increase, while decrease pressure drop. High-velocity exhaust coupled with larger holes can improve both uniformity and pressure drop. The uniformity index increased from 97.6% of the original design to 98.7% of the optimized design, while pressure drop increased from 11.20 to 12.09 kPa. Weighing the relationship between inflow uniformity and pressure drop is an issue worthy of attention.

To investigate the adsorption kinetics and thermodynamic adsorption mechanism and laws of dry flue gas desulfurization, we prepared a new adsorbent by loading Cr, Cu, and Zn on TiO 2 -loaded multiwalled carbon nanotubes. Desulfurization experiments were also carried out. In this study, three kinds of samples were used for simulation and diffusion processes in the dynamic adsorption of different SO 2 volume fractions in flue gas and thermodynamic model analysis of different temperatures in flue gas. Results show that the diffusion coefficient of SO 2 in three kinds of samples ranges from 10 −16 to 10 −14  m 2  s −1 , and the diffusion may be dominated by configuration diffusion. The intraparticle diffusion model predicts that the performance improves with an increase in the SO 2 volume fraction and a shift of adsorption time. This finding indicates that an increase in SO 2 volume fraction and a change in adsorption time increase the Kundsen diffusion specific gravity and decrease the configuration diffusion specific gravity, thereby increasing the SO 2 diffusion resistance, which becomes faster than the activation energy barrier resistance in the catalytic oxidation reaction. Thus, the diffusion resistance specific gravity increases in the total resistance of the diffusion reaction. One possible mechanism of the adsorption process is the transition to surface reaction control at the early stage of adsorption to joint control of late diffusion and surface reactions. Adsorption thermodynamics studies show that SO 2 adsorption by three adsorbents is a spontaneous, exothermic, and entropic reduction process, and the increase in temperature is inconducive for SO 2 adsorption in three samples.

The combustion instability in a propulsion system is a ubiquitous problem. The radial baffles usually installed on the injector faceplate eliminate the combustion instability (acoustic pressure oscillation) in the propulsion system. In this article, the longitudinal baffles are installed on the inner surface of the combustor wall to control the combustion instabilities. The first-order and second-order tangential modes are induced in the experiments. The effects of the parameters of the baffle on the acoustic pressure oscillation in the cylindrical combustor are investigated. The effect of the combustor nozzle on the tangential modes has been systematically investigated. It is concluded that the eigen-frequency and amplitude of the first-order tangential mode decline with the increase in the longitudinal baffle number and height. For the second-order tangential mode, the eigen-frequency and amplitude monotonically increase until a maximum value (four baffles), subsequently decrease with the increase in the baffle number and height. The combustor without the nozzle obtains a lower frequency than that with the nozzle, especially for the low baffle height in the combustor.

In this paper, we examine conservation laws (Cls) with conformable derivative for certain nonlinear partial differential equations (PDEs). The new conservation theorem is used to the construction of nonlocal Cls for the governing systems of equation. It is worth noting that this paper introduces for the first time, to our knowledge, the analysis for Cls to systems of PDEs with a conformable derivative.

The key purpose of this study is to suggest a new fractional extension of Hermite–Hadamard, Hermite–Hadamard–Fejér and Pachpatte-type inequalities for harmonically convex functions with exponential in the kernel. Taking into account the new operator, we derived some generalizations that capture novel results under investigation with the aid of the fractional operators. We presented, in general, two different techniques that can be used to solve some new generalizations of increasing functions with the assumption of convexity by employing more general fractional integral operators having exponential in the kernel have yielded intriguing results. The results achieved by the use of the suggested scheme unfold that the used computational outcomes are very accurate, flexible, effective and simple to perform to examine the future research in circuit theory and complex waveforms.

This article studies dark, bright, trigonometric and rational optical soliton solutions to the perturbed nonlinear Schrödinger–Hirota equation (PNLSHE). Hence, we have examined two cases: first, restrictions have been done to the third-order (TOD) ( γ ) as constraint relation, and the coupling coefficients ( σ ) is obtained as well as the velocity of the soliton by adopting the traveling wave hypothesis. Second, the TOD and the coupling coefficients are non-zero value, sending back to the PNLSHE, which has been studied in refs. [4,10,16] recently. By employing two relevant integration technics such as the auxiliary equation and the modified auxiliary equation method, miscellaneous optical solitary wave is obtianed, which is in agreement with the outcomes collected by the previous studies [4,16]. These results help in obtaining nonlinear optical fibers in the future.

This article scrutinizes the efficacy of analytical mathematical schemes, improved simple equation and exp ( − Ψ ( ξ ) ) (-\text{&#x03A8;}(\xi )) -expansion techniques for solving the well-known nonlinear partial differential equations. A longitudinal wave model is used for the description of the dispersion in the circular rod grounded via transverse Poisson’s effect; similarly, the Boussinesq equation is used for extensive wave propagation on the surface of water. Many other such types of equations are also solved with these techniques. Hence, our methods appear easier and faster via symbolic computation.

The present paper applies the variation of ( G ′ / G ) (G^{\prime} /G) -expansion method on the space-time fractional Hirota–Satsuma coupled KdV equation with applications in physics. We employ the new approach to receive some closed form wave solutions for any nonlinear fractional ordinary differential equations. First, the fractional derivatives in this research are manifested in terms of Riemann–Liouville derivative. A complex fractional transformation is applied to transform the fractional-order ordinary and partial differential equation into the integer order ordinary differential equation. The reduced equations are then solved by the method. Some novel and more comprehensive solutions of these equations are successfully constructed. Besides, the intended approach is simplistic, conventional, and able to significantly reduce the size of computational work associated with other existing methods.

Humans are part of nature, and as nature existed before mankind, mathematics was created by humans with the main aim to analyze, understand and predict behaviors observed in nature. However, besides this aspect, mathematicians have introduced some laws helping them to obtain some theoretical results that may not have physical meaning or even a representation in nature. This is also the case in the field of fractional calculus in which the main aim was to capture more complex processes observed in nature. Some laws were imposed and some operators were misused, such as, for example, the Riemann–Liouville and Caputo derivatives that are power-law-based derivatives and have been used to model problems with no power law process. To solve this problem, new differential operators depicting different processes were introduced. This article aims to clarify some misunderstandings about the use of fractional differential and integral operators with non-singular kernels. Additionally, we suggest some numerical discretizations for the new differential operators to be used when dealing with initial value problems. Applications of some nature processes are provided.

The Sinh–Poisson equation and the RLC transmission line equation are important nonlinear model equations in the field of engineering and power transmission. The modified simple equation (MSE) procedure is a realistic, competent and efficient mathematical scheme to ascertain the analytic soliton solutions to nonlinear evolution equations (NLEEs). In the present article, the MSE approach is put forward and exploited to establish wave solutions to the previously referred NLEEs and accomplish analytical broad-ranging solutions associated with parameters. Whenever parameters are assigned definite values, diverse types of solitons originated from the general wave solutions. The solitons are explained by sketching three-dimensional and two-dimensional graphs, and their physical significance is clearly stated. The profiles of the attained solutions assimilate compacton, bell-shaped soliton, peakon, kink, singular periodic, periodic soliton and singular kink-type soliton. The outcomes assert that the MSE scheme is an advance, convincing and rigorous scheme to bring out soliton solutions. The solutions obtained may significantly contribute to the areas of science and engineering.

This article concerns with the development of the number of focal values. We analyzed periodic solutions for first-order cubic non-autonomous ordinary differential equations. Bifurcation analysis for periodic solutions from a fine focus z = 0 {\mathfrak{z}}=0 is also examined. In particular, we are interested to detect the maximum number of periodic solutions for various classes of higher order in which a given solution can bifurcate under perturbation of the coefficients. We calculate the maximum number of periodic solutions for different classes, namely, C 10 , 5 {C}_{10,5} and C 12 , 6 {C}_{12,6} with trigonometric coefficients, and they are found with nine and eight multiplicities at most. The classes C 8 , 3 {C}_{8,3} and C 8 , 4 {C}_{8,4} with algebraic coefficients have at most eight limit cycles. The new formula ϰ 10 {\varkappa }_{10} is developed by which we succeeded to find highest known multiplicity ten for class C 9,3 {C}_{\mathrm{9,3}} with polynomial coefficient. Periodicity is calculated for both trigonometric and algebraic coefficients. Few examples are also considered to explain the applicability and stability of the methods presented.

In this study, the behavior of a microchannel flow is examined. The fluid is considered to be a nanofluid, which moves between two parallel flat plates in the presence of an electrical double layer. The Buongiorno nanofluid is considered with body force. In this study, the unphysical supposition presented in the preceding work to the discontinuity of the flow fled where the electrostatic potential in the central of the canal must be equal to zero is removed. The incorrect supposition that the pressure constant is preserved, which is considered a known form, is corrected. The current fresh model equation is modified by using dimensionless parameters to convert partial differential equations into ordinary differential equations. The transformed nonlinear equations are solved by the homotopy analysis method. The physical parameters, magnetic parameters, Eckert number, Lewis number, Brownian motion parameters, thermophoresis parameters, and Prandtl number are analyzed. The influence of both the viscous and Joule dissipation in the presence of magnetohydrodynamic effect is examined.

Tick-borne encephalitis (TBE) is a flaviviral vector-borne disease, which is spread by a tick named Ixodes persulcatus in domestic animals as well as in humans. In this article, susceptible, exposed, infected, recovered model; with no immunity after getting recovered is taken. The only possible immunity is before getting the disease (in our model). The vaccination details are also discussed in the article. Hence, SEIS (susceptible, exposed, infected and again susceptible with zero removal from the specie compartment) is used to construct a mathematical model of TBE. TBE is acute inflammation of the brain parenchyma. After becoming viral in European states and some Asian countries, especially in China, this is an emerging viral disease in Pakistan. After constructing a model, formula for the basic reproduction number R 0 -like threshold has been derived by using the next-generation matrix method. The formula for R 0 -like threshold is used to evaluate whether the disease is going to be outbroken in the respective area from which the specific data are taken into consideration. The main motivation behind selection of this topic is to address the unawareness of this disease specifically in Pakistan and in its neighboring countries when there persists probability for the outbreak of this disease. Some equilibrium points and their local stability is also discussed. Numerical computations and graphs are also presented to validate the results.

In this article, analytical exact and approximate solutions for fractional physical equations are obtained successfully via efficient analytical method called fractional residual power series method (FRPSM). The fractional derivatives are described in the Caputo sense. Three applications are discussed, showing the validity, accuracy and efficiency of the present method. The solution via FRPSM shows excellent agreement in comparison with the solutions obtained from other established methods. Also, the FRPSM can be used to solve other nonlinear fractional partial differential equation problems. The final results are presented in graphs and tables, which show the effectiveness, quality and strength of the presented method.

In the present study, we deal with the space–time fractional KdV–MKdV equation and the space–time fractional Konopelchenko–Dubrovsky equation in the sense of the conformable fractional derivative. By means of the extend ( G ′ G ) \left(\tfrac{G^{\prime} }{G}\right) -expansion method, many exact solutions are obtained, which include hyperbolic function solutions, trigonometric function solutions and rational solutions. The results show that the extend ( G ′ G ) \left(\tfrac{G^{\prime} }{G}\right) -expansion method is an efficient technique for solving nonlinear fractional partial equations. We also provide some graphical representations to demonstrate the physical features of the obtained solutions.

In this article, a modified variational iteration method along with Laplace transformation is used for obtaining the solution of fractional-order nonlinear convection–diffusion equations (CDEs). The proposed technique is applied for the first time to solve fractional-order nonlinear CDEs and attain a series-form solution with the quick rate of convergence. Tabular and graphical representations are presented to confirm the reliability of the suggested technique. The solutions are calculated for fractional as well as for integer orders of the problems. The solution graphs of the solutions at various fractional derivatives are plotted. The accuracy is measured in terms of absolute error. The higher degree of accuracy is observed from the table and figures. It is further investigated that fractional solutions have the convergence behavior toward the solution at integer order. The applicability of the present technique is verified by illustrative examples. The simple and effective procedure of the current technique supports its implementation to solve other nonlinear fractional problems in different areas of applied science.

The aim of this study is to investigate the heat and mass transport over a stretchable surface. The analysis is prolonged to the concept of thermal radiations and chemical reaction over a differentially heated surface with internal heating. This is significant from an engineering and industrial point of view. The nonlinear model is successfully attained by adopting the similarity transforms and then further computation is done via a hybrid Runge–Kutta algorithm coupled with shooting technique. The behavior of fluid velocity and heat and mass transport are then furnished graphically for feasible ranges of parameters. A comprehensive discussion of the results is provided against multiple parameters. Foremost, the local thermal performance and mass transport rate are explained via numerical computation. The major outcomes of the study are described in the end.

In this article, a new continuous model of a peptide group system with higher order saturable nonlinearity is derived. The model is constructed up on discrete Schrodinger equation with higher order saturable nonlinearity. New exact solutions of the proposed model are investigated. Via the generalized Riccati equation mapping method travelling wave and soliton solutions are derived. For certain values of parameters kink, antikink, breathers, and dark and bright solitons are presented.

In this study, the Daftardar–Jeffery polynomials are incorporated in the homotopy of the optimal homotopy asymptotic method (OHAM) for solving the generalized Hirota–Satsuma coupled system of Korteweg–de Vries equations. The results are displayed through graphs and tables. The results obtained in this study are also compared with the published work on OHAM, which shows that OHAM-DJ is more explicit, reliable, and an efficient analytical technique. The exactness of the developed method can be improved by performing the higher iterations.

Nanofluid bioconvective channel flow is an essential aspect of the recent healthcare industry applications, such as biomedical processing systems. Thus, the present work examined the influence of n th order chemical reaction in an unsteady nanofluid bioconvective channel flow in a horizontal microchannel with expanding/contracting walls. The suitable form of the similarity transformation is exercised to transform the governing boundary layer equations into a more straightforward form of system to ease the computation process. The Runge–Kutta method of fifth-order integration technique solved the reduced boundary layer system and generated the numerical results as the governing parameters vary. It is found that the destructive second-order chemical reaction enhances the mass transfer rate at the lower wall but deteriorates the mass transfer rate at the upper wall. The upper channel wall has a better heat transfer rate than the lower wall when the Reynolds number increases.

The purpose of this proposed investigation is to study unsteady magneto hydrodynamic (MHD) mixed initial-boundary value problem for incompressible fractional Maxwell fluid model via oscillatory porous rectangular duct. Considering the modified Darcy’s law, the problem is simplified by using the method of the double finite Fourier sine and Laplace transforms. As a limiting case of the general solutions, the same results can be obtained for the classical Maxwell fluid. Also, the impact of magnetic parameter, porosity of medium, and the impact of various material parameters on the velocity profile and the corresponding tangential tensions are illuminated graphically. At the end, we will give the conclusion of the whole paper.

In this article, the Sinh–Gordon function method and sub-equation method are used to construct traveling wave solutions of modified equal width equation. Thanks to the proposed methods, trigonometric soliton, dark soliton, and complex hyperbolic solutions of the considered equation are obtained. Common aspects, differences, advantages, and disadvantages of both analytical methods are discussed. It has been shown that the traveling wave solutions produced by both analytical methods with different base equations have different properties. 2D, 3D, and contour graphics are offered for solutions obtained by choosing appropriate values of the parameters. To evaluate the feasibility and efficacy of these techniques, a nonlinear evolution equation was investigated, and with the help of symbolic calculation, these methods have been shown to be a powerful, reliable, and effective mathematical tool for the solution of nonlinear partial differential equations.

Multi-term time-fractional partial differential equations (PDEs) have become a hot topic in the field of mathematical physics and are used to improve the modeling accuracy in the description of anomalous diffusion processes compared to the single-term PDE results. This research includes the numerical solutions of two-term time-fractional PDE models using an efficient and accurate local meshless method. Due to the advantages of the meshless nature and ease of applicability in higher dimensions, the demand for meshless techniques is increasing. This approach approximates the solution on a uniform or scattered set of nodes, resulting in well-conditioned and sparse coefficient matrices. Numerical tests are performed to demonstrate the efficacy and accuracy of the proposed local meshless technique.

In this article, a fast algorithm is developed for the numerical solution of twelfth-order boundary value problems (BVPs). The Haar technique is applied to both linear and nonlinear BVPs. In Haar technique, the twelfth-order derivative in BVP is approximated using Haar functions, and the process of integration is used to obtain the expression of lower-order derivatives and approximate solution for the unknown function. Three linear and two nonlinear examples are taken from literature for checking the convergence of the proposed technique. A comparison of the results obtained by the present technique with results obtained by other techniques reveals that the present method is more effective and efficient. The maximum absolute and root mean square errors are compared with the exact solution at different collocation and Gauss points. The convergence rate using different numbers of collocation points is also calculated, which is approximately equal to 2.

In this article, the system for the long–short-wave interaction (LS) system is considered. In order to construct some new traveling wave solutions, He’s semi-inverse method is implemented. These solutions may be applicable for some physical environments, such as physics and fluid mechanics. These new solutions show that the proposed method is easy to apply and the proposed technique is a very powerful tool to solve many other nonlinear partial differential equations in applied science.

Fractal-fractional (FF) differential and integral operators having the capability to subsume features of retaining memory and self-similarities are used in the present research analysis to design a mathematical model for the rubella epidemic while taking care of dimensional consistency among the model equations. Infectious diseases have history in their transmission dynamics and thus non-local operators such as FF play a vital role in modeling dynamics of such epidemics. Monthly actual rubella incidence cases in Pakistan for the years 2017 and 2018 have been used to validate the FF rubella model and such a data set also helps for parameter estimation. Using nonlinear least-squares estimation with MATLAB function lsqcurvefit , some parameters for the classical and the FF model are obtained. Upon comparison of error norms for both models (classical and FF), it is found that the FF produces the smaller error. Locally asymptotically stable points (rubella-free and rubella-present) of the model are computed when the basic reproduction number ℛ 0 { {\mathcal R} }_{0} is less and greater than unity and the sensitivity is investigated. Moreover, solution of the FF rubella system is shown to exist. A new iterative method is proposed to carry out numerical simulations which resulted in getting insights for the transmission dynamics of the rubella epidemic.

In this article, exact solutions of some Laplace-type fractional boundary value problems (FBVPs) are investigated via natural decomposition method. The fractional derivatives are described within Caputo operator. The natural decomposition technique is applied for the first time to boundary value problems (BVPs) and found to be an excellent tool to solve the suggested problems. The graphical representation of the exact and derived results is presented to show the reliability of the suggested technique. The present study is mainly concerned with the approximate analytical solutions of some FBVPs. Moreover, the solution graphs have shown that the actual and approximate solutions are very closed to each other. The comparison of the proposed and variational iteration methods is done for integer-order problems. The comparison, support strong relationship between the results of the suggested techniques. The overall analysis and the results obtained have confirmed the effectiveness and the simple procedure of natural decomposition technique for obtaining the solution of BVPs.

Steel plates bi-axially loaded are characterized by mechanical deformations whose 2D image representations are very difficult to achieve. In this work, the authors propose an innovative approach based on eddy current techniques for obtaining 2D electrical maps to assess the mechanical integrity of a steel plate. The procedure, also exploiting fuzzy similarity computations, translates the problem of the assessment of the mechanical integrity of a steel plate into a suitable classification problem. The results obtained by this proposed procedure show performances comparable to those provided by well-established soft computing approaches with a higher computational complexity.

The paper addresses the uncertainty quantification of physical and geometrical material parameters in the design of wireless power transfer systems. For 3D complex systems, a standard Monte Carlo cannot be directly used to extract statistical quantities. So, surrogate models based on Kriging or polynomial chaos expansions are built to study the impact of variable parameters on the radiated magnetic field and efficiency. Such fast prediction of uncertainties in the parameters of the system can improve the design of inductive power transfer systems taking into account human exposure recommendations and variability of the parameters.

Outer-rotor permanent magnet machines for low-speed and high-torque applications have been used due to their high moment of inertia and torque density. In this paper, the 12-slot/10-pole outer-rotor fractional-slot permanent magnet machine model is established by finite element analysis, the influence of unequal stator tooth width and tooth tip width is investigated for the PM machine, and five different schemes of stator tooth and tip width are designed and analyzed. Detailed comparisons of the performance characteristics of the machines are presented including important issues such as output torque, magnetic field distribution, and tooth flux density. It is shown that the torque density and cogging torque and efficiency can be effectively improved by choosing reasonable tooth and tip width, which lays a foundation for further optimum design and efficiency improvement of the machine.

Reluctance forces are the main cause of vibration in electrical machines. The influence of magnetostriction is still the matter of controversy. In the article, program Ansys (typical for finite element method) was used to analyze stator deformation due to magnetic forces (Maxwell and magnetostriction) for the different boundaries and different methods by taking into account the windings in the mechanical model. Different parameters of numerical model are important factors affecting the level of magnetostriction deformation.

With the development of electrical machines for achieving higher performance and smaller size, heat generation in electrical machines has also increased. Consequently, the temperature rise in electrical machines causes unexpected heating of components and makes it difficult to operate properly. Therefore, in the development of electrical machines, the accurate evaluation of temperature increase is important. In the thermal design of electrical machines, heat-conduction analysis using the heat-transfer boundary set on the surface of a heated target has been frequently performed. However, because the heat-transfer coefficient is dependent on various factors, it is often determined based on experimental or numerical simulation results. Therefore, setting the heat-transfer coefficient to a constant value for the surface of the heated target degrades the analysis accuracy because the actual phenomenon cannot be modeled. To enhance the accuracy of the heat-transfer coefficient, the coupled electromagnetic field with heat-conduction analysis finite element method (FEM), thermal-fluid analysis using FEM, and the highly simplified marker and cell method is applied to the estimation of the distribution of the heat-transfer coefficient. Moreover, to accurately calculate the localized heat-transfer coefficient, the temperature distribution and flow velocity distribution around the heated target are analyzed in the induction-heating apparatus.

In this article, an experimental procedure is presented to handle magnetic measurements under uniaxial tensile stress reaching the plastic domain. The main advantage of the proposed procedure is that it does not require an additional magnetic core to close the magnetic flux path through the studied sample. The flux flows only in the sample, and no parasitic air gaps are introduced, thus avoiding the use of the H-coil to evaluate the magnetic field, which is often very sensitive and not easy to calibrate. A specimen of nonoriented FeSi (1.3%) sheet (M330-35A) is characterized under uniaxial tensile stress. To validate the proposed procedure, a comparison with the single sheet tester procedure is carried out. The results obtained by the two procedures are in good agreement. Moreover, to illustrate the possibilities offered by the proposed procedure, we confirm some results obtained in the literature. We show that the positive plastic strain leads to a significant degradation of magnetic behavior. An applied tensile stress on a virgin (unstrained) sample leads to a degradation of the magnetic behavior. However, on a pre-strained sample, an applied tensile stress results in reducing the deterioration caused by the plastic strain until a stress value called optimum is attained. Above this threshold, the magnetic behavior re-deteriorates progressively.

The high electrical stresses in the Electrical Insulation Systems of machines fed by pulse width modulation (PWM) inverters remain a limitation of the lifetime. The stress is caused by repetitive over voltages caused by the short switching times of the PWM inverter power electronic circuit. This paper provides measurements made on an industrial drive connected to the grid with standard cables that include a ground connection wire, following the current standards. The phase-to-phase, phase-to-neutral, and neutral-to-ground voltages are measured focusing on short and repetitive voltage spikes. The causes of these voltage spikes are analyzed using a high frequency equivalent circuit of the whole drive, including the earthing system. The simulations are made with the well-known SPICE circuit simulator. This study focuses on the common-mode currents flowing in the earthing connections and its influence on voltage spikes. A solution that can reduce significantly the phase-to-neutral voltage spikes is proposed.

This paper aims to present and analyze the materials adapted to design a machine that can work with a high current density without any specific cooling system. In other words, the machine is equipped with material that supports high internal temperature, about 500°C. Candidate materials are selected and the authors indicate that inorganic insulation should be preferred for conductors and slot insulations. Tests are carried out on material selection through measurement of the turn-to-turn voltage, insulation resistances, and the parallel capacitances.

The article proposes an analysis of the possible architectures of synchronous machines with an ability to operate at high temperatures of over 200°C in their environment. Two machine principles have been considered: the permanent magnet synchronous machine and the synchronous reluctance machine. The numerical analyses are carried out with 3D-coupled electromagnetic-fluid-thermal models; the electromagnetic one provides the local losses that give the input data to the coupled thermal-fluid analysis model for computing the temperatures inside the machines. The simulation results are used for estimating the temperature limit of each machine architecture, considering the characteristics of their critical parts.

The Maxwell stress tensor (MST) method is commonly used to accurately compute the global efforts, such as electromagnetic torque ripple and unbalanced electromagnetic forces in electrical machines. The MST has been extended to the estimation of local magnetic surface force for the vibroacoustic design of electrical machines under electromagnetic excitation. In particular, one common air-gap surface force (AGSF) method based on MST is to compute magnetic surface forces on a cylindrical shell in the air gap. However, the AGSF distribution depends on the radius of the cylindrical shell. The main contribution of this study is to demonstrate an analytic transfer law of the AGSF between the air gap and the stator bore radius. It allows us to quantify the error between the magnetic surface force calculated in the middle of the air gap and the magnetic force computed on the stator teeth. This study shows the strong influence of the transfer law on the computed tangential surface force distribution through numerical applications with induction and synchronous electrical machines. Finally, the surface force density at stator bore radius is more accurately estimated when applying the new transfer law on the AGSF.

The increase of the operating temperature of electrical machines is a major challenge in the context of the large-scale use of electricity in many industrial or individual applications such as mobility. Indeed, working at higher temperatures makes it possible to place electrical actuators in critical areas – such as aircraft engines, for example – and/or to significantly improve the power-to-weight ratio of the machine. For several applications (deep pumping, ventilation, etc.), the use of the induction machine is still preferred due to cost, simplicity and robustness essentially. The objective of this study is to estimate the possibilities of making a high-temperature squirrel cage induction machine. A significant increase in the operating temperature of a machine would indirectly allow us to envisage an increase in the current density in the active conductors and thus a significant improvement in the power-to-weight ratio. However, this is at the sacrifice of efficiency. The aim of this study is to evaluate this decrease in efficiency correlated with the increase in the temperature to find the best compromise according to the relevant applications. An analytic sizing model has been proposed for the prediction of losses, which will be coupled with a thermal model to predict the temperature in different parts of the machine. This study presents essential information on the influence of temperature on the parameters important for the performance of an induction machine.

The aim of this study is to present the possibilities of reducing the size of large induction motors with new electrical materials taken into account of thermal constraints. This study highlights the possibilities of reducing losses, increasing the efficiency, and decreasing the weight, by taking different grades of materials. A nonlinear multiobjective optimization is used to determine the best solution, by varying the internal and external geometric parameters.

Emotions are commonly considered to be the most expressive of everyday human experiences, giving a sense of fullness and reality of life. The ability to recognize human emotions as a manifestation of higher intelligence is desirable feature. There are several models of emotional experience that can become the basis for building a universal emotional recognition system. In this article, we check the correctness of the designed emotional model. We check the evaluation of the system’s operation by human observers.

This paper studies the performance of an axial-flux switched reluctance machine (AFSRM) using GOES (grain-oriented electrical steel) in its rotor and comparing it to a NOES (non-oriented electrical steel) rotor. Indeed, the AFSRM structure lends itself well to the use of GOES, especially at the rotor. In order to evaluate the intrinsic capabilities of the AFSRM, self-inductance versus rotor position and static torque were numerically simulated at a given operating point and used as indicators for the NOES and GOES performance comparison. The static torque is also used to determine and compare the torque per volume ratios and grasp the impact of GOES use in a 3D rotating structure. The introduction of GOES in a rotating machine leads to an improvement of the electromagnetic torque mean and maximum values, allowing to evaluate the GOES impact on the machine performance.

This erratum corrects the typing mistakes of the article “Conserved vectors with conformable derivative for certain systems of partial differential equations with physical applications,” published in Open Physics 2020;18(1):164–9, https://doi.org/10.1515/phys-2020-0127 .