Stationary Transfer Equation Research Articles

A new model of the impact of information dissemination with emotional responses on disease transmission in multilayer networks

During disease transmission, the dissemination of information about the disease prompts safety concerns among individuals. Individuals’ various emotional responses to information may affect infection prevention measures and, consequently, disease transmission. In this paper, we propose a new coupled information and disease transmission model with emotional factors in multiplex networks. Our specific focus is on the impact of diverse emotional responses on the dynamics process. We employ the Microscopic Markov Chain Approach (MMCA) to analyze the model, and obtaining state transfer equations, and deriving the disease transmission threshold. Extensive numerical simulations show that dissemination of information by relevant authorities motivates individuals to adopt scientific self-protective behaviors, thus helping to control disease transmission. Furthermore, individuals who have different emotional responses after obtaining information have varying effects on disease transmission, and reducing the anxiety response or increasing the calm response of individuals can more effectively decrease the scale of disease transmission and increase the disease transmission threshold. In summary, improving the quality of information released by the emergency management department, reducing the individual’s anxiety response, and encouraging the adoption of positive and effective protective measures are of paramount importance for epidemic prevention and control.

Influence of the Schottky Junction on the Propagation Characteristics of Shear Horizontal Waves in a Piezoelectric Semiconductor Semi-Infinite Medium

In this paper, a theoretical model of the propagation of a shear horizontal wave in a piezoelectric semiconductor semi-infinite medium is established using the optimized spectral method. First, the basic equations of the piezoelectric semiconductor semi-infinite medium are derived with the consideration of biased electric fields. Then, considering the propagation of a shear horizontal wave in the piezoelectric semiconductor semi-infinite medium, two equivalent mathematical models are established. In the first mathematical model, the Schottky junction is theoretically treated as an electrically imperfect interface, and an interface characteristic length is utilized to describe the interface effect of the Schottky junction. To legitimately confirm the interface characteristic length, a second mathematical model is established, in which the Schottky junction is theoretically treated as an electrical gradient layer. Finally, the dispersion and attenuation curves of shear horizontal waves are numerically calculated using these two mathematical models to discuss the influence of the Schottky junction on the dispersion and attenuation characteristics of shear horizontal waves. Utilizing the equivalence of these two mathematical models and the above numerical results, the numerical value of the interface characteristic length is reliably legitimately confirmed; this value is independent of the thickness of the upper metal layer, the doping concentration of the lower n-type piezoelectric semiconductor substrate, and biasing electric fields. Only the biasing electric field parallel to the Schottky junction can provide an evident influence on the attenuation characteristics of shear horizontal waves and enhance the interface effect of the Schottky junction. Since the second mathematical model is also a validation of our previous mathematical model established through the state transfer equation method, some numerical results calculated using these two mathematical models are compared with those obtained using the previous method to verify the correctness and superiority of the research work presented in this paper. Since these two mathematical models can better calculate the dispersion and attenuation curves of high-frequency waves in micro- and nano-scale piezoelectric semiconductor materials, the establishment of mathematical models and the revelation of physical mechanisms are fundamental to the analysis and optimization of micro-scale resonators, energy harvesters, and amplifications.

AN STABILITY ESTIMATE IN 3D SOURCE PROBLEM FOR THE STATIONARY RADIATIVE TRANSFER EQUATION

It is given a stability estimate of a solution of a source problem for the stationary radiative transfer equation. It is suppose that the source is an isotropic distribution. Earlier stability estimates for this problem were studied in several papers, the most part of those was related to a partial case of the emission tomography problem, when the scattering operator vanishes. For the complete transfer equation the stability estimate were given under additional conditions for the absorption coefficient and the scattering kernel, those are sufficiently difficult for checking. Moreover, it is still open the question about dependence a constant in the stability estimate on the coefficients of the transfer equation. In the present work, the stationary transfer equation is considered in an compact strongly convex domain of the tree-dimension space. In a forward problem it is assumed that incoming radiation is absent. In an inverse problem for recovering an unknown source some data for solutions of the forward problem are given. A new simple approach is suggested to obtain a stability estimate for the problem under the consideration. Using this way, an explicit constant in this estimate is given.

Rayleigh wave in layered piezoelectric semiconductor with consideration of PN junction effects

In this paper, analytical solutions for Rayleigh wave in a transversely isotropic piezoelectric semiconductor (PSC) substrate with a covering layer of different type doping are obtained. The PN junction (called also the depletion layer), which is created by the diffusion and drifting due to the different doping type of the substrate and the covering layer, can be considered as an electrically gradient layer between the covering layer and the substrate. Making use of the state transfer equation method, the transfer matrix of the state vector of the depletion layer is derived mathematically. Based on the numerical calculations, we investigate the physical influences of the covering layer, electric boundary conditions and doping concentrations on the dispersion and attenuation, and the effects of PN junction on the wave-mode shapes. Our results show that the semiconductor will slow the Rayleigh waves and induce the attenuation. Both the phase velocity and attenuation are dependent upon the frequency. The existence of PN junction has less influences on the dispersion and attenuation but relatively large influences on the wave-mode shapes, especially, on the electric potential, carriers concentration, electric displacement, and the current density of carriers.

Influences of piezoelectric positive-negative junction on the multi-field coupled waves propagation in the piezoelectric semiconductor.

The influences of the piezoelectric positive-negative junction (PN junction) between two semiconductors with different doping types on the multi-field coupled wave propagation are studied in the present work. The layered structures of semiconductors are often used in intelligent devices, and the PN junction plays an important role for performance improvement. Due to the migration and diffusion of carriers, the electric potential and concentration of the carrier are graded distribution in the PN junction. This inhomogeneity results in the reflection and transmission of coupled waves, which are the complex of multiple physical fields including the mechanical, electric, and carrier fields. The state transfer equation method is used to obtain the transfer matrix of the PN junction, and the reflection and transmission waves under the plane strain situation are evaluated numerically. The energy fluxes of the reflection and transmission waves are estimated and used to validate the numerical results by the check of energy conservation. It is found that PN junction effects hinder the wave propagation and drastically enhance the reflection ability of the interface, especially, on the coupled carrier waves, and thus are very important and cannot be ignored for the wave propagation problem. The influences of external applied stress and bias electric field are also discussed.

A Hybrid Method to Predict the Remaining Useful Life of Scroll Wheel of Control Rod Drive Mechanism

As one of the rotating components in the reluctance motor type control rod drive mechanism (CRDM), the life of the scroll wheel is closely related to the service life of the CRDM. In addition, the prediction of the remaining useful life of the scroll wheel helps to optimize the maintenance process of the CRDM. This paper proposes a hybrid method to predict its remaining useful life when the available degradation data are rare and the failure threshold cannot be accurately defined. First, the particle filtering algorithm, whose state transfer equation is established on the segmental damage physical model, is used to predict the degradation state of the scroll wheel. Second, the proportional hazard model for the relationship between the scroll wheel damage characteristics and reliability model is established to predict the remaining useful life of it. The proposed method focuses on the establishment of segmental damage physical model and the clustering analysis of damage characteristics extracted from vibration signals, which can be used to predict the remaining useful life of the scroll wheel. In addition, the results provide an opportunity for the condition-based preventive maintenance of the CRDM.

Shear horizontal wave in a piezoelectric semiconductor substrate covered with a metal layer with consideration of Schottky junction effects

In this paper, the shear horizontal wave in a transversely isotropic piezoelectric semiconductor substrate covered with a metal layer are obtained. The Schottky junction, which is created by the n-type piezoelectric semiconductor and the metal with a lower Fermi level, is considered as an electrically gradient layer between the layer and the substrate. Making use of the state transfer equation method, the transfer matrix of the state vector of the space charge region is derived mathematically. Basing on the numerical calculations, we investigate the physical influences of the doping density, Schottky junction and covered layer thickness on the dispersion and attenuation and the effects of Schottky junction on the wave mode shapes. Our results show that the Schottky junction has negligible influences on the dispersion curve and displacement and stress mode shapes but evident influences on the attenuation curve and the mode shapes of electric potential, electric displacement, carrier perturbation density and the electric current density.

Reflection and transmission of coupled elastic waves by a semiconduction interlayer with consideration of photothermal effects.

The wave propagation problem through an inhomogeneous semiconduction slab sandwiched between two thermoelastic half-spaces is studied in this paper. Due to the photothermal effects and photoacoustic effects, the multiple physical fields coupled waves are generated in the semiconduction interlayer. For the inhomogenous semiconduction slab of finite thickness, the multiple physical fields coupled waves cannot be expressed explicitly. Instead, the state vector is defined, and the state transfer equation is derived to obtain the transfer matrix of the inhomogeneous slab. The reflection and transmission coefficients as well as the dissipation energy are estimated. The influences of the photothermal effects and photoacoustic effects are discussed based on the numerical results. It is found that the photothermal effects and photoacoustic effects result in some different vibration modes and associated propagation modes. The gradient profiles of the inhomogeneous interlayer have complicated influences on the reflection and transmission behaviors and can be well-designed to adjust the propagation behavior.

An Indoor Navigation Algorithm Using Multi-Dimensional Euclidean Distance and an Adaptive Particle Filter.

The inertial navigation system has high short-term positioning accuracy but features cumulative error. Although no cumulative error occurs in WiFi fingerprint localization, mismatching is common. A popular technique thus involves integrating an inertial navigation system with WiFi fingerprint matching. The particle filter uses dead reckoning as the state transfer equation and the difference between inertial navigation and WiFi fingerprint matching as the observation equation. Floor map information is introduced to detect whether particles cross the wall; if so, the weight is set to zero. For particles that do not cross the wall, considering the distance between current and historical particles, an adaptive particle filter is proposed. The adaptive factor increases the weight of highly trusted particles and reduces the weight of less trusted particles. This paper also proposes a multidimensional Euclidean distance algorithm to reduce WiFi fingerprint mismatching. Experimental results indicate that the proposed algorithm achieves high positioning accuracy.

Thermoelastic wave and thermal shock based on dipolar gradient elasticity and fractional-order generalized thermoelasticity

In the current work, the thermoelastic wave propagation and the thermal shock problems are studied based on the dipolar gradient elasticity and fractional order generalized thermoelasticity in order to take into account the microstructure effect and the thermal effect at a small scale. First, the fractional-order governing equations for coupled thermoelastic wave propagation are derived and the effects of microstructure parameters and fractional order on the dispersion and the attenuation are discussed; next, the transient problems by the thermal shock and the mechanical shock on the surface of half-space are studied. The Laplace transformation method and the state transfer equation method are used to solve this problem. The numerical results for the temperature, the displacement, the stress and the high order stress distributions are provided and shown graphically. The effects of the fractional order and the microstructure parameter on the thermoelastic behavior are investigated. Some interesting phenomenons and conclusions are presented at last.

Multi-stage timetable rescheduling for high-speed railways: a dynamic programming approach with adaptive state generation

A dynamic programming (DP) approach with adaptive state generation and conflicts resolution is developed to address the timetable-rescheduling problem (TRP) at relatively lower computation costs. A multi-stage decision-making model is first developed to represent the timetable-rescheduling procedure in high-speed railways. Then, an adaptive state generation method by reordering the trains at each station is proposed to dynamically create the possible states according to the states of previous stages, such that the infeasible states can be removed and the search space is reduced. Then, conflicts are resolved by retiming the arrival and/or departure times of trains. Furthermore, the state transfer equation is built and Bellman equation is developed to derive the solution to minimize the total delay time (TT). A series of simulation experiments and a real-world case study are used to evaluate the performance of the proposed method. The simulation experiments indicate that the proposed method is able to find the optimal timetable with appropriate overtaking at right stations and reduce the total delay by 62.7% and 41.5% with respect to the First-Come-First-Serve (FCFS) and First-Schedule-First-Serve (FSFS) strategy that are widely used in practice. Comparing to the intelligent scheduling method (e.g., Ant Colony Optimization and Particle Swarm Optimization), similar objective performance can be achieved at a much lower cost of computation time, which make the proposed method more applicable to the TRP in daily operation of high-speed railway.

Remaining Useful Life Prediction of Lithium Batteries Based on Extended Kalman Particle Filter

The prognosis of time‐to‐failure for a battery can avoid the failure caused by battery performance loss. In this paper, a novel and effective algorithm is proposed to predict the remaining useful life of lithium‐ion batteries. The extended Kalman particle filter is used to improve particle degradation problem existing in standard particle filter algorithm. In order to fit battery capacity degradation, a transformed model is proposed based on double exponential empirical degradation model. It can reduce the number of parameters and the training difficulty of parameters; it also matches the form of state transfer equation. In order to improve prediction accuracy, the auto regression model is introduced to correct observation values produced by observation equation. Experimental results show that the proposed algorithm can effectively improve the accuracy of prediction compared with other algorithms. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Theory and Experiment of Enclosing Control for Second-Order Multi-Agent Systems

This article investigates the enclosing control without preset formation of second-order multi-agent systems for stationary targets. This article uses a directed graph to describe and the direction of information exchange between agents and targets. For continuous-time systems, an enclosing control algorithm is proposed, which does not need to preset the desired formation. The state transfer equation is used to transform the solution of the system into a matrix function of first-order linear constant-coefficient non-homogeneous differential equations. By analyzing the convergence of the solution, the value range of the gain parameter is obtained, and the requirements of topology are proposed. Then the discrete protocol is applied to the discrete-time system. Based on the Schur stability analysis of the system, the requirements of topology and parameter for the system to achieve enclosing control are given. Finally, the self-designed multi-agent platform is introduced, and simulation and experimental results are presented to validate the effectiveness of the protocol.

Path planning for drones reconnaissance based on ant colony algorithms

Firstly, the traditional ant colony algorithm is introduced. Then it compares the difference between drone reconnaissance path planning problem and TSP. improving the traditional ant colony algorithm, which constrains the state transfer equation of ant colony algorithm so that the algorithm can simultaneously Planning multiple paths. Finally, we conducted an example analysis of road detection in Puerto Rico with the DroneGo disaster response system, and covered the island with a minimum number of drones.

Multi-Timescale Decision and Optimization for HVAC Control Systems With Consistency Goals

Many optimization problems for heating, ventilation, and air conditioning (HVAC) control systems usually refer to multiple timescales. This paper studies a two-timescale decision problem for indoor temperature regulation by HVAC with the objective to improve user’s comfort under limited energy consumption. A slow timescale is divided into several fast timescales, so the two timescales have inherent association. Using states of fast timescale to represent the state of its slow timescale properly is challenging, thereby the weighted mean type is proposed in this paper. We find that the realizability and consistency in two-timescale cannot be guaranteed in existing empirical models, which are the bases for physical application. Therefore, this paper proposes a method that building the fast timescale model first and then inducing the slow timescale model from the fast timescale model. In addition, such a problem in the high-order system is more complex, whose solution is also discussed in this paper. The results of case studies show that the induced model can guarantee the consistency and realizability and meet the user desired temperature for comfort. Note to Practitioners —This paper was motivated by the multi-timescale problem that making a decision of controlling the indoor temperature for the user’s comfort with energy constraint. Existing approaches to build a two-timescale model by experience would cause the inconsistent deviation. If the HVAC works in a closed environment system like a space station, besides crew comfort, the temperature for experiments in the space station should be accurate. Therefore, the deviation from the actual temperature and the desired temperature will cause adverse effects. In this paper, we mathematically derive the thermal state transfer equations and analyze some problems. Then, this paper suggests a new approach to build the two-timescale model for various conditions, in which the models of two timescales are consistent with each other. Preliminary experiments suggest that this approach is feasible and effective. In future research, we will jointly make optimization and decision of multiple appliances in home energy management (HEM) system.

Effects of functionally graded interlayers on dispersion relations of shear horizontal waves in layered piezoelectric/piezomagnetic cylinders

• Dispersive relations of SH guide waves in layered PE/PM cylinders are studied. • Seven kinds of gradient profiles of graded interlayers are considered. • Four kinds of mechanical and electromagnetic surfaces are considered. • Direct integration of graded interlayer is used instead of layer-wise homogenization. • The radial variation of vibration form for low and high order modes is studied. The effects of functionally graded interlayers on dispersion relations of shear horizontal waves in layered piezoelectric/piezomagnetic cylinders are studied. First, the basic physical quantities of elastic waves in piezoelectric cylinder are derived by assuming that the SH waves propagate along the circumferential direction steadily. Then the transfer matrices of the functional graded interlayer and outer piezomagnetic cylinder are obtained by solving the state transfer equations with spatial-varying coefficients. Furthermore, making use of the electro-magnetic surface conditions of the outer cylinder, the dispersion relations for the shear horizontal waves in layered piezoelectric/piezomagnetic cylinders are obtained and the numerical results are shown graphically. Seven kinds of functionally graded interlayers and four kinds of electro-magnetic surface conditions are considered. It is found that the functionally graded interlayers have evident influences on the dispersion relations of shear horizontal waves in layered piezoelectric/piezomagnetic cylinders. The high order modes are more sensitive to the gradient interlayers while the low order modes are more sensitive to the electro-magnetic surface conditions.

Wave propagation through a flexoelectric piezoelectric slab sandwiched by two piezoelectric half-spaces

Reflection and transmission of plane waves through a flexoelectric piezoelectric slab sandwiched by two piezoelectric half-spaces are studied in this paper. The secular equations in the flexoelectric piezoelectric material are first derived from the general governing equation. Different from the classical piezoelectric medium, there are five kinds of coupled elastic waves in the piezoelectric material with the microstructure effects taken into consideration. The state vectors are obtained by the summation of contributions from all possible partial waves. The state transfer equation of flexoelectric piezoelectric slab is derived from the motion equation by the reduction of order, and the transfer matrix of flexoelectric piezoelectric slab is obtained by solving the state transfer equation. By using the continuous conditions at the interface and the approach of partition matrix, we get the resultant algebraic equations in term of the transfer matrix from which the reflection and transmission coefficients can be calculated. The amplitude ratios and further the energy flux ratios of various waves are evaluated numerically. The numerical results are shown graphically and are validated by the energy conservation law. Based on these numerical results, the influences of two characteristic lengths of microstructure and the flexoelectric coefficients on the wave propagation are discussed.

Love waves on a half-space with a gradient piezoelectric layer by the geometric integration method

ABSTRACTThe propagation of Love waves on an elastic homogeneous half-space with a piezoelectric gradient covering layer is studied by the geometric integration method in this article. First, the state transfer equation of a Love wave is derived from the governing equations and constitutive relations. Then, the transfer matrix of the state vector is obtained by solving the state transfer equation of a Love wave and then the stiffness matrix is obtained. By combining transfer matrices and the stiffness matrices of the gradient covering layer and the homogeneous half-space, the total surface stiffness matrix of a Love wave is obtained. Lastly, the application of the electrically open circuit and short circuit conditions and mechanically traction-free conditions gives the frequency dispersive relation of a Love wave. For the gradient covering layer, the material constants at the bottom of the covering layer may be greater or smaller than that at the top of the covering layer. The two situations and three kinds of gradient profiles for each of these two situations are investigated. The numerical results show that the Love wave speed is sensitive to not only the material constants at the bottom and the top of the covering layer, but also the gradient profiles of the covering layer.

Research on Tracking Algorithm for Fast-Moving Target in Sport Video

Tracking of player actions from sports video sequence is the hotspot in computer vision technology. The state transfer equation and the observing equation In the target tracking system are often nonlinear and non-gauss and mean shift algorithm cannot track the visual target effectively. The paper analyzes the principle and the shortage of the traditional mean shift algorithm. The reason for its weakness is analyzed too. A new tracking algorithm that combines the particle filtering and mean shift is proposed In order to effectively trace the fast-moving target. It estimates the position by particle filter in the previous frame of the targets. The position of the target is updated by the mean shift algorithm. Experimental comparisons show that it has better fusion performance for tracking the fast-moving players in sport video.

Wave propagation through an inhomogeneous slab sandwiched by the piezoelectric and the piezomagnetic half spaces

Wave propagation through a gradient slab sandwiched by the piezoelectric and the piezomagnetic half spaces are studied in this paper. First, the secular equations in the transverse isotropic piezoelectric/piezomagnetic half spaces are derived from the general dynamic equation. Then, the state vectors at piezoelectric and piezomagnetic half spaces are related to the amplitudes of various possible waves. The state transfer equation of the functionally graded slab is derived from the equations of motion by the reduction of order, and the transfer matrix of the functionally gradient slab is obtained by solving the state transfer equation with the spatial-varying coefficient. Finally, the continuous interface conditions are used to lead to the resultant algebraic equations. The algebraic equations are solved to obtain the amplitude ratios of various waves which are further used to obtain the energy reflection and transmission coefficients of various waves. The numerical results are shown graphically and are validated by the energy conservation law. Based on the numerical results on the fives of gradient profiles, the influences of the graded slab on the wave propagation are discussed. It is found that the reflection and transmission coefficients are obviously dependent upon the gradient profile. The various surface waves are more sensitive to the gradient profile than the bulk waves.