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The present paper deals with the thermal memory response of wave propagation in an unbounded, homogeneous, isotropic elastic body, emanating from a spherical cavity. To analyze the memory response, the generalized heat conduction model with the fractional order as well as memory-dependent-derivatives (MDDs) concepts are considered. The solution space is obtained in Laplace transform domain by using the eigenfunction expansion method to the vector-matrix form of the corresponding governing equations. Finally, a comparison study is furnished for thermal displacement, stresses, and temperature changes in the space-time domain and is presented graphically. [ABSTRACT FROM AUTHOR]

This paper deals with an M/M/c balking retrial queue with vacation. Both single and multiple vacation policies are analysed. This system is investigated as a quasi-birth-and-death process. Using the matrix-geometric method, we derive the useful formulae for computing the rate matrix and stationary probabilities. Various system performance measures are further developed in the matrix-form expressions. We construct a cost function to determine the optimum value of servers and the optimum mean service rate subject to the stability condition at minimum cost. Quasi-Newton method, Nelder-Mead simplex method and simulated annealing method are employed to perform the optimization tasks. Under optimum operating conditions, we provide the numerical results for a comparison of vacation policies. An application example is given to illustrate the system's potential applicability. [ABSTRACT FROM AUTHOR]

Conic sections have many applications in industrial design, however, they cannot be exactly represented in polynomial form. Hence approximating conic sections with polynomials is a challenging problem. In this paper, we use the monomial form of Delgado and Peña (DP) curves and present a matrix representation for them. Using the matrix form and the least squares method, we propose a simple and efficient algorithm for approximating conic sections by DP curves of arbitrary degree with endpoint interpolation. Finally, we test and compare the proposed algorithm on some numerical examples which validates and confirms efficiency of it. [ABSTRACT FROM AUTHOR]

Digital assets are highly vulnerable and always prone to malicious intervention. Identification of causes of such intervention for timely support and assistance remains a key challenge for businesses to remain functional and thrive with the competition. A framework is proposed in this paper for identifying cyber risk, threat, and countermeasure, based on breach databases and textual information processing. Alongside, a multi-objective optimisation of a mixed-integer non-linear problem (MINLP) is made post linearisation to find out a suitable trade-off between cyber risk and investment. The model helps in effective decision-making by finding the proneness of suppliers (as nodes) in the sequence of reducing vulnerability and pairing of categorised factors. The web scrapping and historical databases are processed to extract relationships among categorised factors using natural language processing (NLP). Pareto optimal pairs are obtained to explain the application of the current contribution in terms of risk-cost trade-off. It helps in forming preventive strategies with a suitable amount of investment and the required order of precedence or susceptibility. [ABSTRACT FROM AUTHOR]

Many numerical methods for computing radiation exchange in enclosures are based on the computation of direct exchange areas (DEAs) and total exchange areas (TEAs). Excessively long computation times can be associated with TEAs computation. Among the best performing methods, the plating algorithm (PA) computes TEAs from DEAs based on a set of simple recursive equations. An efficient CPU and GPU parallelization of the PA are represented. Nevertheless, PA computation complexity isO(N3). A novel formulation, the nonrecursive plating algorithm (NRPA), is introduced. It allows the computation of TEAs with a single nonrecursive step. Its equations are formulated by identification to the PA equations giving TEAs from DEAs, requiring one simple assumption. The NRPA is then written in matrix form as mainly a square matrix multiplication operation. Based on advancement in matrix multiplication computation, the NRPA complexity is proven to beO(N2.38) for the number of multiplications. CPU and GPU NRPA are implemented based on the optimized linear algebra library BLAS for CPU and cuBLAS for GPU CUDA programs. NRPA is found to highly outperform PA in both CPU and GPU computation times. Finally, a test enclosure is considered and serves to validate the accuracy of the NRPA by comparison to the PA. [ABSTRACT FROM AUTHOR]

In this article, the M/M/k/N/N queue is modeled as a continuous-time homogeneous Markov system with finite state size capacity (HMS/cs). In order to examine the behavior of the queue a continuous-time homogeneous Markov system (HMS) constituted of two states is used. The first state of this HMS corresponds to the source and the second one to the state with the servers. The second state has a finite capacity which corresponds to the number of servers. The members of the system which can not enter the second state, due to its finite capacity, enter the buffer state which represents the system's queue. In order to examine the variability of the state sizes formulae for their factorial and mixed factorial moments are derived in matrix form. As a consequence, the pmf of each state size can be evaluated for any t ∈ ℝ+. The theoretical results are illustrated by a numerical example. [ABSTRACT FROM PUBLISHER]

The article investigates the acqusition, structure, magnetic properties and magnetoresistance effect of nanocomposites on the basis of polypropylene matrix and iron nanoparticles, structure, magnetic properties and magnetoresistance. AFM results illustrate that the increase in the volume content of Fe nanoparticles in the polymer matrix causes changes on its supramolecular structure. As a result of the MFM studies, it has been defined that, nanoparticles dispersed in the polymer matrix form domains in the local areas and the sizes of domains vary from 150 to 400 nm. The study of magnetic properties of PP + Fe based nanocomposites showed that intrinsic magnetization increases with increasing magnetic field intensity and saturation occurs at certain value of intensity. If the field is reduced, remanent magnetization and hysterezis loop is observed. The dependence of PP + Fe based nanocomposites on the magnetic field was investigated and magnetoresistive effect was observed and it was found to be related with the presence of tunneling magnetoresistance effect in these nanocomposites. [ABSTRACT FROM AUTHOR]

I argue that teaching evaluation tools (TETs) may function as ethical codes (ECs), and answer certain demands that ECs cannot sufficiently fulfill. In order to be viable, an EC related to the teaching profession must assume a different form, and such a form is already present in several of the contemporary TETs. The TET matrix form allows for certain features that are incompatible with the EC form. The TET’s benchmark scale - ranging from below the acceptable to the ideal level across the dimensions of teachers’ competence - allows it to answer the demands upon ECs, raised by the EC critics. TETs embrace both minimal requirements and lofty ideals, while ECs of different types have a hard time combining these two features. TETs relate to different dimensions of teacher competence, connecting ethical and professional components with didactical, managerial and cognitive components, without lumping them together. [ABSTRACT FROM AUTHOR]

In this paper, the topological structure properties of deterministic finite automata (DFA), under the framework of the semi-tensor product of matrices, are investigated. First, the dynamics of DFA are converted into a new algebraic form as a discrete-time linear system by means of Boolean algebra. Using this algebraic description, the approach of calculating the limit cycles of different lengths is given. Second, we present two fundamental concepts, namely, domain of attraction of limit cycle and prereachability set. Based on the prereachability set, an explicit solution of calculating domain of attraction of a limit cycle is completely characterised. Third, we define the globally attractive limit cycle, and then the necessary and sufficient condition for verifying whether all state trajectories of a DFA enter a given limit cycle in a finite number of transitions is given. Fourth, the problem of whether a DFA can be stabilised to a limit cycle by the state feedback controller is discussed. Criteria for limit cycle-stabilisation are established. All state feedback controllers which implement the minimal length trajectories from each state to the limit cycle are obtained by using the proposed algorithm. Finally, an illustrative example is presented to show the theoretical results. [ABSTRACT FROM AUTHOR]

We study periodic Lyapunov matrix equations for a general discrete-time linear periodic system $ B_px_p-A_px_{p-1}=f_p $ B p x p − A p x p − 1 = f p , where the matrix coefficients $ B_p $ B p and $ A_p $ A p can be singular. The block coefficients of the inverse operator of the system are referred to as the Green matrices. We derive new decay estimates of the Green matrices in terms of the spectral norms of special solutions to the periodic Lyapunov matrix equations. The study is based on the periodic Schur decomposition of matrices. [ABSTRACT FROM AUTHOR]

Panel data model with fixed effects is widely used in economic and administrative applications. However, the presence of factors: measurement errors, data variability and outliers may potentially decrease the accuracy of the model prediction. In this paper, we use panel interval-valued data to represent measurement errors and data volatility of observations. Further, we propose a corresponding panel interval-valued data model with fixed effects, in which both the response and explanatory variables are interval-valued data. To reduce the impact of outliers on our model, we propose a robust estimation method based on the iterative weighted least squares technique. Later, Monte Carlo simulation and empirical application demonstrate that our model is a suitable tool for analyzing the behaviour of panel interval-valued data. [ABSTRACT FROM AUTHOR]

This paper is devoted to the descriptions of automorphisms and local automorphisms on complex solvable Lie algebras of maximal rank. First, it is established that any automorphism on a solvable Lie algebra of maximal rank can be represented as a product (composition) of inner, diagonal and graph automorphisms. We apply the description of automorphism to the specification of automorphisms on solvable Lie algebras of maximal rank with abelian nilradical, and to the description of automorphisms of standard Borel subalgebras of complex simple Lie algebras. Based on the representation of an automorphism, it is proved that all local automorphisms on a solvable Lie algebra of maximal rank are global automorphisms. We also present two examples of solvable Lie algebras which are not of maximal rank and have different behaviours of local automorphisms. Namely, the first algebra does not admit pure local automorphisms, while the second algebra admits a local automorphism which is not an automorphism. [ABSTRACT FROM AUTHOR]

In this work, we characterize the fixed points of the doubly stochastic operators defined on discrete spaces $ \ell ^p(I) , $ ℓ p (I) , where I is a nonempty set and $ p\in [1,+\infty). $ p ∈ [ 1 , + ∞). We use our results to characterize all Markov chains with infinite state space and doubly stochastic transition probability matrix that have at least one stationary distribution vector. [ABSTRACT FROM AUTHOR]

Rack railway is a rail transportation that utilizes the gear-rack engagement to supply the traction forces on large-slope lines, primarily employed in mountainous regions where the conventional trains cannot operate due to the wheel-rail adhesion limitations. However, there is limited research on this system dynamics and further analysis is required to understand the interaction mechanism between the rack vehicle and track. Based on the typical vehicle-track coupled dynamics theory, the rack vehicle-track spatially coupled dynamics model is developed in this paper to evaluate the dynamic behaviours of the rack vehicle and the track system running on large-slope line with a detailed modeling of the longitudinal motion for the rack and sleeper, where the time-varying gear-rack mesh stiffness and the rail geometrical irregularity are incorporated. The excellent agreement observed between simulated and field-test results serves as strong validation for developed dynamics model. The results demonstrate that the vibration responses of the wheelset and the rack are dominated by the gear-rack mesh excitations. It should be noticed that the wheel loads are reduced by the presence of the gear-rack engagement. Furthermore, the vibration of the sleeper can explicitly reflect the gear-rack mesh characteristics through the transfer of the rack fastener. [ABSTRACT FROM AUTHOR]

Many students who enroll in a first course in linear algebra major in STEM disciplines other than mathematics. Teachers who serve such students may find it difficult to provide authentic problems from these broader areas that ignite students' interest in linear algebra. In this paper, we highlight an interdisciplinary learning activity that engages students in using linear systems of equations to model the behavior of practical electric circuits. This exercise fits nicely into standard introductory linear algebra curricula and is designed to excite students majoring in engineering, physics, or applied mathematics. We also include references to a collection of open-access resources to support instructors who want to use this material in project-based, flipped-learning, inquiry-oriented, or independent-study environments. [ABSTRACT FROM AUTHOR]

Split-step quantum walk operators can be expressed as a generalized version of CMV operators with complex transmission coefficients, which we call rotated CMV operators. Following the idea of Cantero, Moral and Velazquez's original construction of the original CMV operators from the theory of orthogonal polynomials on the unit circle (OPUC), we show that rotated CMV operators can be constructed similarly via a rotated version of OPUCs with respect to the same measure, and admit an analogous $ \mathcal {LM} $ LM -factorization as the original CMV operators. We also develop the rotated second kind polynomials corresponding to the rotated OPUCs. We then use the $ \mathcal {LM} $ LM -factorization of rotated alternate CMV operators to compute the Gesztesy–Zinchenko transfer matrices for rotated CMV operators. [ABSTRACT FROM AUTHOR]

Currently, there are two main clustering perforation methods: coiled tubing-conveyed perforation (TCP) and cable-conveyed perforation (CCP). To improve the efficiency of CCP strings in wellbore pass-through capacity problems, considering wellbore geometry constraints, pipe string variable cross-section, flexible tool deformation, and other factors, the pass-through capacity analysis model of the perforating tool string was established and solved by geometric analysis and beam-column theory. Aiming at the running depth problem of a TCP string, considering the influence of the buckling effect, a model of coiled tubing running depth was established by the infinitesimal method. The field test data were used to verify the effectiveness of the two models. The effects of well trajectory, perforating string size, casing inner diameter, and coiled tubing size on the pass-through capacity of the CCP string and running depth of the TCP string were explored. The results indicate that with the increase of perforation string size or the reduction of casing inner diameter, the pass-through capacity of CCP string decreases; with the increase of coiled tubing specification, the running capacity of TCP string is improved. The work presented in this paper provides an effective analysis method and theoretical guidance for clustering perforation jobs in the field. [ABSTRACT FROM AUTHOR]

Fixture layout is an essential factor in intelligent manufacturing in the shipbuilding industry, affecting assembly quality and efficiency. Its optimization has become an urgent problem in the assembly process of compliant parts. Traditional fixture layout depends on workers' experience, which leads to butt clearance along the assembly interface. Thus, this article proposes a butt clearance control-oriented fixture layout optimization (BCCFLO) methodology. First, a method for calculating the part dimensional variation under the influence of fixture layout and fixture locating error is developed. Then, a constrained multi-objective integer nonlinear programming (CMINP) model is innovatively formulated to optimize the fixture layout. Furthermore, the non-dominated sorting genetic algorithm-II based on Latin hypercube sampling is designed to address the CMINP model. The case study illustrates and validates that the fixture layout achieved by the proposed method could significantly control the butt clearance for large compliant part assembly in the shipbuilding industry. [ABSTRACT FROM AUTHOR]

Riverbank and in-stream protection are crucial in numerous river stretches, where erosion of banks and bed material instigates river course alterations, consequently leading to land and property damage. In large Indian braided rivers like Brahmaputra, implementing tetrahedron frames commonly referred to as 'porcupines' has emerged as a cost-effective strategy for river training, yielding commendable outcomes in near bank sedimentation. Using flexible river training structures, such as porcupine, presents an appealing option for managing braided river channel networks in areas where permanent control structures like groynes or dams prove excessively costly or potentially ineffective, particularly in systems exhibiting highly dynamic flow regimes and morphology. This work aims to develop a hydrodynamic model that integrates the porcupine systems within its framework. The model's effectiveness was assessed through a field test near Nematighat, Brahmaputra River, in collaboration with Assam's Water Resources Department. The mathematical modelling provided some valuable insights regarding the flow characteristics surrounding the porcupine structure, shedding light on its hydrodynamic behaviour. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of prescribed-time fault-tolerant control for the formation of quadrotors by utilising the fully-actuated system approach. Since not all quadrotors can directly access the virtual leader's state, a distributed prescribed-time observer is designed to estimate the state of a virtual leader. Leveraging this observer, a horizontal position controller that combines the fully-actuated system approach with the prescribed-time method, as well as altitude and attitude fault-tolerant controller, are proposed. In the design of control law, two distinct sets of controllers are designed: asymptotically stable controller and prescribed-time controller, each tailored to specific control objectives. The proposed distributed prescribed-time observer can ensure that the estimation error of the leader's state reaches zero within any specified time interval. Finally, the numerical simulation is conducted to demonstrate the effectiveness of the proposed fault-tolerant formation control algorithm. [ABSTRACT FROM AUTHOR]

This paper solves the problem of designing positive functional $ H_{\infty } $ H ∞ filters for positive linear time-delay systems. In fact, we propose a new positive reduced order $ H_{\infty } $ H ∞ filter for positive linear constant state time-delay systems for which the states remain in the nonnegative orthant of the state space, subject to disturbances and unknown inputs. This paper is a first attempt to design positive unknown inputs functional $ H_{\infty } $ H ∞ filter for such positive linear delayed systems. The proposed approach is based on the positivity of an augmented system composed of dynamics of both considered system and proposed filter, on the unbiasedness of the estimation error by the resolution of Sylvester equation and also on Lyapunov-Krasovskii stability theory; then conditions for the establishment of such filters are formulated in terms of an optimization problem. An algorithm that summarizes the different steps of the proposed positive functional $ H_{\infty } $ H ∞ filter design is given. Finally, numerical example and simulation results are given to illustrate the effectiveness of the proposed design method. [ABSTRACT FROM AUTHOR]

Composite sandwich structures are predominantly used in aerospace, civil engineering works, and automotive industries for load-bearing and lightweight structures. Recently, the core structures have been getting modified, due to the lack of strength, stiffness, and weight ratio. Very few past researches have shown research data on testing and mechanical properties of sandwich structures with commercial Kevlar honeycomb as a core. To overcome the above-said issues, an innovative composite sandwich structure is designed with carbon fibre resin-based sheets and a Kevlar honeycomb core. Carbon fibre face sheets with a thickness of 0.8 mm also an Aerospace Grade Kevlar honeycomb core with a cell size of 3.2 mm, a density of 48 kg/mm3 and a height of 12.7 mm are used to build the proposed sandwich structure. The fabricated sandwich plate was then subjected to various tests by American Standards for Testing and Materials (ASTM) standards to determine the various mechanical properties, such as stiffness, pressure, and stresses. Also, water absorption and soil degradation experiments were conducted on a sandwich plate to describe the additional properties of this sandwich structure. As a result, the specimen produced by the proposed method has low weight with high load withstanding capability as the shear is restricted with the help of carbon fibre also it has low deflection at critical load and high strength. [ABSTRACT FROM AUTHOR]

This paper derives a general Bartlett correction formula to improve the inference based on the likelihood ratio test in a multivariate model under a quite general parameterization, where the mean vector and the variance-covariance matrix can share the same vector of parameters. This approach includes a number of models as special cases such as non-linear regression models, errors-in-variables models, mixed-effects models with non-linear fixed effects, and mixtures of the previous models. We also employ the Skovgaard adjustment to the likelihood ratio statistic in this class of multivariate models and derive a general expression of the correction factor based on Skovgaard approach. Monte Carlo simulation experiments are carried out to verify the performance of the improved tests, and the numerical results confirm that the modified tests are more reliable than the usual likelihood ratio test. Applications to real data are also presented for illustrative purposes. [ABSTRACT FROM AUTHOR]

This article explores a novel data-driven approach based on recent developments in Koopman operator theory and dynamic mode decomposition (DMD) for modeling signalized intersections. On signalized intersections, vehicular flow and queue formation have complex nonlinear dynamics, making system identification, modeling, and controller design challenging. We employ a DMD-type approach to transform the original nonlinear dynamics into locally linear infinite-dimensional dynamics. The data-driven approach relies entirely on spatio-temporal snapshots of the traffic data. We investigate several key aspects of the approach and provide insights into the usage of DMD-type algorithms for application in adaptive signalized intersections. To validate the obtained linearized dynamics, we perform prediction of the queue lengths at the intersection and compare the results with the benchmark methods such as ARIMA and long short term memory (LSTM). The case study involves intersection pressure and queue lengths at two Orlando area signalized intersections during the morning and evening peaks. It is observed that DMD-type algorithms are able to capture complex dynamics with a linear approximation to a reasonable extent. The merits include faster computation times and significantly less requirement for a "lookback" (training) window. [ABSTRACT FROM AUTHOR]

A new Phase II control chart, which is based on the change-point model and combined with the exponentially weighted moving average (EWMA) mechanism, is proposed to monitor general linear profiles. The new control chart can be used to monitor general linear profiles when the true in-control parameters are unknown, and only a few historical data are available. In addition, when the chart triggers an out-of-control signal, not only can it estimate the location of the change point, it can also identify which of the parameters have changed as well as the change directions. Using Monte-Carlo simulations, the proposed chart is shown to be effective and has good diagnostic performance. Furthermore, the simulation results show that the proposed chart has better performance than the existing charts in most of the out-of-control scenarios considered. An example is used to illustrate how the proposed chart can be implemented in practical applications. [ABSTRACT FROM AUTHOR]

This study aims to discuss queueing modeling of machine repair problems under threshold recovery policy (Q), server unreliability and k-type phase repairs. When one or more machines in the system fails/fail, the service facility (or all $R$ R -servers) is activated and repairs the failed machine according to the first come, first served (FCFS) discipline. The service facility may experience a partial or complete breakdown while providing service and needs to be repaired in required phases under the threshold recovery policy (Q). The matrix geometric approach is applied to solve the system governing equations, and a sensitivity analysis is presented to understand the effect of various parameters on system performance metrics. The greedy selection method and the golden section method are used to compute optimal rates of $\left({{R^*}, {\mu ^*}} \right)$ R ∗ , μ ∗ of service facility in order to minimize the cost function of the system. [ABSTRACT FROM AUTHOR]

A two-level data set can be structured in either long format (LF) or wide format (WF), and both have corresponding SEM approaches for estimating multilevel models. Intuitively, one might expect these approaches to perform similarly. However, the two data formats yield data matrices with different numbers of columns and rows, and their cols : rows is related to the magnitude of eigenvalue bias in sample covariance matrices. Previous studies have shown similar performance for both approaches, but they were limited to settings where cols ≪ rows in both data formats. We conducted a Monte Carlo study to investigate whether varying cols : rows result in differing performances. Specifically, we examined the p : N ( cols : rows ) effect on convergence and estimation accuracy in multilevel settings. Our findings suggest that (1) the LF approach is more likely to achieve convergence, but for the models that converged in both, (2) the LF and WF approach yield similar estimation accuracy, which is related to (3) differential cols : rows effects in both approaches, and (4) smaller ICC values lead to less accurate between-group parameter estimates. [ABSTRACT FROM AUTHOR]

Despite the popularity of traditional fit index cutoffs like RMSEA ≤.06 and CFI ≥.95, several studies have noted issues with overgeneralizing traditional cutoffs. Computational methods have been proposed to avoid overgeneralization by deriving cutoffs specifically tailored to the characteristics of the model being evaluated. Simulations show favorable performance of these methods; however, these methods support a narrow set of scenarios (e.g., certain models or response scales) and the interpretation of cutoffs is not always standardized, which affects empirical researchers' ability to confidently and broadly adopt these methods to evaluate model fit. In this paper, we propose an extension to one recently developed computational method—dynamic fit index cutoffs—that (a) permits application to any covariance structure model (e.g., CFA, mediation, bifactor), (b) standardizes interpretation of cutoffs across any covariance structure model, and (c) supports normal, nonnormal, categorical, and missing data. Software is provided to facilitate implementation of the method. [ABSTRACT FROM AUTHOR]

This paper implements the stochastic filters for state and parameter estimation of nonuniform transmission lines (NTL). In general, transmission line (TL) problem is a continuous time and space problem. By taking the line loading noise into account, the TL equations become a stochastic partial differential equation (PDE) rather than a simple set of coupled finite stochastic differential equations (SDE). By transforming the spatial variables into the Fourier domain, the stochastic PDE can be transformed into an infinite sequence of SDE. After truncation to a finite set of Fourier series coefficients, it becomes a finite set of coupled linear SDE, which is the required domain in which extended Kalman filter (EKF) and unscented Kalman filter (UKF) can be applied. For state space equation of EKF and UKF, the voltage and current of periodic NTL are expanded into an infinite set of spatial harmonics. In this way, the voltage and current measurement of NTL become an eigenvalue problem. The NTL is considered as cascade of small infinite NTL and the four distributed primary parameters of the periodic NTL are expressed using Fourier series expansion. Finally, the Kalman filter (KF)-based state estimation and the EKF- and UKF-based parameter estimation have been compared with recursive least squares (RLS) method. The simulation results present the superiority of the method. [ABSTRACT FROM AUTHOR]

The affine formation maneuver (AFM) control problem using the zero-sum differential game is studied for a second-order multi-agent system (MAS) against cyber-injection attacks on the actuators. First and foremost, the distributed control signals and the cyber-injected attack signals are viewed as two competing teams. Then, the leader-follower tracking error system is established where the followers aim to track the AFMs of the leaders. The leader-follower distributed optimal control policies and the cyber-attack attenuation policies are derived from the Nash equilibrium solution of the Hamilton-Jacobi-Isaac (HJI) equation. The solution of the HJI equation is estimated with the aid of the critic neural network. The weights of the critic system are learned online based on the adaptive dynamic programming (ADP) scheme. The uniformly ultimately bounded stability of the closed-loop system under the formulated zero-sum differential game control strategy has been proven by the Lyapunov stability theorem. A simulation example illustrates that the presented control method can attenuate cyber-injection attacks on the actuators and maintain the AFMs of the agents. [ABSTRACT FROM AUTHOR]

The in-wheel motor (IWM) is a promising advancement in electric vehicle propulsion since it offers greater packaging efficiency and torque vectoring capabilities than a chassis-mounted motor. However, the increased unsprung mass degrades the vehicle dynamics by increasing body vertical acceleration (BVA) and tyre dynamic load (TDL), worsening ride comfort and road-holding respectively. Another important consideration is magnetic gap deformation (MGD), which results from the deflection between the motor stator and rotor. Reducing MGD improves the motor reliability and longevity. This paper addresses these issues by incorporating inerters into an existing IWM model. They are incorporated into the strut and bushes to control BVA, TDL and MGD. The system optimised for MGD resulted in a deflection reduction of over 98% without compromising performance of the other indices. Optimising the strut and bushes for BVA and TDL reduced them by 20% and 9% respectively without degrading MGD. A sensitivity analysis of the results is presented. Here the damping and inertance values are varied by 20% from the optimum, and the resulting performance still improves upon the default. It is concluded that there are significant potential improvements where inerters are included in an in-wheel motor system. [ABSTRACT FROM AUTHOR]

In the current paper, hygro-thermo-magnetically induced vibrations of small-scale viscoelastic tubes containing flow with a spin motion under gravity and tangential loads are analyzed by including surface effects. The dynamic equations are derived in the framework of the modified nonlocal elasticity theory (NET) and Rayleigh beam model. The Galerkin method and Laplace transformation are implemented to solve model equations. Vibration frequencies, stability boundaries, and Campbell diagrams of the system are acquired. Impacts of influential parameters such as scale rotary inertia factor, scale parameter, viscoelastic materials, gravity and tangential loads, flow and spin velocities, geometrical properties, and environmental conditions on the stability of the structure are examined. Also, the obtained results are compared for the Rayleigh and Euler-Bernoulli (EB) beam models. The golden results of this work are that by fine-adjusting the scale parameter and magnetic intensity in the system, destructive effects of hygro-thermal loads can be dampened. Besides, the increment of the rotary inertia factor and nanotube thickness induces destabilizing effect on the system. [ABSTRACT FROM AUTHOR]

In the present work, the general stiffness matrix method is extended in the case of a functionally graded magneto-electro-elastic plate to analyze the free vibration response of a functionally graded composite plate. The material properties are assumed to be continuously graded in the thickness direction. The novelty of this paper is to utilize this efficient method to the dynamic analysis of a wide range of composite (multilayer) plates, with linear or non-linear thickness profiles, and functionally graded in the thickness, without any limitation. The convergence of this method is thoroughly discussed. Here, the converged results are obtained when the number of sub-layer is $ N \le 11 $ N ≤ 11. A parametric study was also conducted to show the effect of gradation of mechanical properties of the composite on the phase velocity and the modal shape. The dynamic model developed here can be used in the graded material design of the functionally graded piezoelectric-piezomagnetic (noted FGPPM) composite plate for achieving specified dynamic characteristics. [ABSTRACT FROM AUTHOR]

The thermoelastic wave propagation analysis is developed in a Love–Bishop nanorod resonator employing the strain gradient elasticity and Green–Naghdi theories with energy dissipation for the first time. The assumed nanorod resonator is subjected to thermal shock loading. The variational principle is applied to derive the coupled system of partial differential equations for temperature and displacement fields in a Love–Bishop nanorod. An analytical solution is proposed to solve the governing equations in Laplace domain. To obtain the temporal variation of fields' variables, a proper Laplace inversion technique is employed in the problem. The size effects in the nano-sized Love–Bishop rods are taken into account with five small-scale parameters including three higher-order materials length parameters, the micro-length inertia and thermal parameters. Two types of thermal shock loadings such as laser pulse-induced suddenly increasing temperature are utilized in this work, and the laser shock-induced thermoelastic wave propagations in both temperature and displacement fields are illustrated. The effects of the higher-order materials length parameters and the micro-length inertia and thermal parameters on the propagation of thermal and elastic waves are studied in detail. [ABSTRACT FROM AUTHOR]

By using the characteristics of two disparate materials (BaTiO $ _3 $ 3 ceramic and PZT-5H ceramic) on SiO $ _2 $ 2 glass, we have analyzed shear horizontal wave (SH wave) propagation through a piezo-visco-elastic composite medium (PVECM). For the better platform of the originality of the situation, the piezo-visco-elastic medium (PVEM) is taken between two elastic materials. The exact solution of the governing equations is obtained and discussed in detail with the variation of various significant parameters. Irregular and irregular free, both boundary conditions are assumed to find relevant results. The influence of viscosity, piezo-electric parameter and dielectric parameter for irregular and irregular free boundaries on SH-wave propagation through BaTiO $ _3 $ 3 ceramic and PZT-5H ceramic materials are shown by some curves. This model contains a huge potential to deal with many commercial and industrial applications. The present investigation has uncovered various crucial results which include for both materials, attenuation coefficient for irregular interface are lower than that of the regular interface. For PZT-5H ceramic material, viscosity, dielectric parameter and piezo-electric parameter have a greater impact on phase velocity and attenuation coefficient in comparison to BaTiO $ _3 $ 3 ceramic. [ABSTRACT FROM AUTHOR]

In this paper, we propose the application of shrinkage strategies to estimate coefficients in the Bell regression models when prior information about the coefficients is available. The Bell regression models are well-suited for modelling count data with multiple covariates. Furthermore, we provide a detailed explanation of the asymptotic properties of the proposed estimators, including asymptotic biases and mean squared errors. To assess the performance of the estimators, we conduct numerical studies using Monte Carlo simulations and evaluate their simulated relative efficiency. The results demonstrate that the suggested estimators outperform the unrestricted estimator when prior information is taken into account. Additionally, we present an empirical application to demonstrate the practical utility of the suggested estimators. [ABSTRACT FROM AUTHOR]

Mangroves are woody plant communities that appear in tropical and subtropical regions, mainly in intertidal zones along the coastlines. Despite their considerable benefits to humans and the surrounding environment, their existence is threatened by anthropogenic activities and natural drivers. Accordingly, it is vital to conduct efficient efforts to increase mangrove plantations by identifying suitable locations. These efforts are required to support conservation and plantation practices and lower the mortality rate of seedlings. Therefore, identifying ecologically potential areas for plantation practices is mandatory to ensure a higher success rate. This study aimed to identify suitable locations for mangrove plantations along the southern coastal frontiers of Hormozgan, Iran. To this end, we applied a hybrid Fuzzy-DEMATEL-ANP (FDANP) model as a Multi-Criteria Decision Making (MCDM) approach to determine the relative importance of different criteria, combined with geospatial and remote sensing data. In this regard, ten relevant sources of environmental criteria, including meteorological, topographical, and geomorphological, were used in the modeling. The statistical evaluation demonstrated the high potential of the developed approach for suitable location identification. Based on the final results, 6.10% and 20.80% of the study area were classified as very-high suitable and very-low suitable areas. The obtained values can elucidate the path for decision-makers and managers for better conservation and plantation planning. Moreover, the utility of charge-free remote sensing data allows cost-effective implementation of such an approach for other regions by interested researchers and governing organizations. [ABSTRACT FROM AUTHOR]

Let $ p_1 \lt p_2 \lt \cdots \lt p_n $ p 1 < p 2 < ⋯ < p n be positive numbers and r a non-negative real number. The Loewner matrix associated with the function $ x^{r+1} $ x r + 1 given by $ L_{r+1}=\begin {bmatrix}\frac {p_i^{r+1}-p_j^{r+1}}{p_i-p_j}\end {bmatrix} $ L r + 1 = [ p i r + 1 − p j r + 1 p i − p j ] and matrix $ P_r=[\begin {smallmatrix}{(p_i+p_j)^r}\end {smallmatrix}] $ P r = [ (p i + p j) r ] (the Hadamard inverse of rth Hadamard power of well-known Cauchy matrix) have same inertia. A question was left open in Inertia of Loewner matrices. Indiana Univ Math J. 2016;65(4):1251–1261 by Bhatia, Friedland and Jain to find a connection between these two matrix families. We aim to answer this question firmly in terms of a congruence relation between $ L_{r+1} $ L r + 1 and $ P_r $ P r . Indeed, a non-singular matrix X over $ \mathbb {R} $ R is explicitly obtained such that $ X'P_rX=L_{r+1} $ X ′ P r X = L r + 1 in this paper. [ABSTRACT FROM AUTHOR]

The dynamic interaction between the vehicle and track is strongly influenced by out-of-round wheels and turnout rail profile geometries, which result in high-magnitude contact forces and abnormal vibrations. This study presents the dynamic response of the tram-turnout interaction due to polygonal wheel wear and analyses its transmission between the wheelsets. A three-dimensional coupled tram-turnout dynamic model was formulated, taking into account the polygonal wear on the front bogie wheelsets. Through numerical simulations, the dynamic characteristics of a tram passing through the turnout switch and crossing panels under the influence of polygonal wear were simulated. Furthermore, the impact of polygonal wear amplitudes and tram speeds on the transmission of dynamic impact forces and vibrations from the front bogie wheelset to the trailer bogie wheels are described. According to the numerical findings, when the flexible wheelset experiences polygonal wear, it can lead to substantial impact forces and vibrations as the tram moves through the turnout switch and crossing zones. Moreover, the transmission of dynamic impact forces and vibrations from the front bogie wheelset to the trailer wheels increases as the wheel wear amplitude and the vehicle speed increase. [ABSTRACT FROM AUTHOR]

In this article, a study of transverse free vibrations of rotating cantilever beams with variable cross-sectional area is carried out using the point collocation method. The study considers four thickness variation functions, including linear, parabolic, sinusoidal, and exponential types, for the beam's cross-sectional area changes. The point collocation method uses Gauss-Legendre points to solve the equation of motion and determine the natural frequencies. To enhance the convergence rate, the initial guess function is based on the precise mode shapes of the stationary uniform beam. The effect of section functions and various rotational speeds on the structure's natural frequencies is investigated. The outcomes of the investigation are compared with 3D finite element simulations and related published results. Through the analysis, the results show that the point collocation method is highly accurate, with a maximum error of 0.0025% compared to 3D finite element simulations. Moreover, the natural frequencies of the rotating cantilever beams decrease as the section functions become steeper. Finally, the increase in rotational speed causes the natural frequencies to increase in a non-linear manner, with the maximum increase rate occurring at a specific rotational speed. [ABSTRACT FROM AUTHOR]

We motivate the advantages of using the Kollo measures, relative to other types of third and fourth moments of multivariate systems, and explore their Monte Carlo simulation and bootstrapping errors. Then we derive necessary and sufficient conditions for simultaneously matching any given mean vector, covariance matrix, Kollo skewness, and Kollo kurtosis. The specification of a suitable orthonormal basis greatly simplifies these moment-matching conditions. We offer semi-closed-form solutions to increase computational efficiency. In this respect, we compare our approach to two competing methods, which anyway can only match Kollo skewness and not the kurtosis at the same time. Ours is the first method for exactly matching all four multivariate moments simultaneously. [ABSTRACT FROM AUTHOR]

To guarantee the stability and performance of an overall heterogeneous multi-agent system, feedback control structures must be capable of addressing the presence of heterogeneous agent-based nonlinear uncertainties, unknown actuation performance, and coupling effects. Additionally, some tasks require agents to track the leader's state and reach different states in a distributed way. Therefore, this paper proposes a distributed adaptive controller that drives a set of agents to user-assigned positions in the presence of the mentioned heterogeneous system anomalies. To address actuator dynamics, a hedging-based reference model is used to decouple adaptive updating from the actuator dynamics. To deal with the coupled dynamics, an observer-based estimation algorithm is proposed. Finally, the low-frequency learning method is used to deal with the high-frequency control response and, therefore, to obtain a better transient performance. The overall closed-loop system's stability is investigated using the Lyapunov Stability Theory, and the Linear Matrix Inequalities (LMI) technique is employed to identify stability limits regarding the actuator bandwidths of each agent. Illustrative numerical examples are presented to demonstrate the designed controller's performance in a heterogeneous uncertain multi-agent system's dynamics with unknown actuation capabilities and coupled dynamics. [ABSTRACT FROM AUTHOR]

This paper deals with the observer design for a class of Interconnected Takagi–Sugeno (TS) systems with Immeasurable Premise Variables (IPV). We first investigate the D-stability of Luenberger-like interconnected multiple observers. However, the resulting constraints can be somewhat conservative due to the use of a common Lyapunov matrix. Then, the so-called Finsler's lemma is used to relax the D-stability conditions through the introduction of additional slack variables providing more flexibility and extra degrees of freedom. The designed conditions are expressed as Linear Matrix Inequalities (LMIs). The proposed approaches are applied in simulation to a Proton Exchange Membrane Fuel Cell (PEMFC) system and a four-tank system. [ABSTRACT FROM AUTHOR]

Surveillance of underwater for maritime warfare is traditionally being carried out by bearings-only tracking from many decades. The measurements used for state estimation here are nonlinear. Also the noise in the measurements and the process cannot be always Gaussian. The traditional nonlinear filtering algorithms like extended Kalman filter and modified gain extended Kalman filter use the linearisation of the system. The unscented Kalman filter (UKF) uses the sigma point approach based on Gaussian distribution to deal with nonlinearity. The particle filter (PF) uses the randomly generated particles based on the pdf of the state. PF is highly complex to implement and it also suffers from sample impoverishment. Hence, ensemble Kalman filter (EnKF) which is a simplified form of PF will be tried out for bearings-only tracking in this research work. The performance of EnKF is compared with PF and UKF and the results obtained using these filters in Matlab are presented. [ABSTRACT FROM AUTHOR]

A modular Gaussian beam model is developed to simulate some ultrasonic testing configurations where multiple interfaces are involved. A general formulation is given in a modular matrix form to represent the Gaussian beam propagation with multiple interfaces. The ultrasonic transducer fields are modeled by a multi-Gaussian beam model which is formed by superposing 10 single Gaussian beams. The proposed model, referred to as the modular multi-Gaussian beam (MMGB) model, is then applied to a typical contact and angle beam testing configuration to predict the output signal reflected from the corner of a vertical crack. The resulting expressions given in a modular matrix form is implemented in a personal computer using the MATLAB program. Simulation results are presented and compared with available experimental results. [ABSTRACT FROM AUTHOR]

A Taylor collocation method is presented for numerically solving the system of high-order linear Fredholm–Volterra integro-differential equations in terms of Taylor polynomials. Using the Taylor collocations points, the method transforms the system of linear integro-differential equations (IDEs) and the given conditions into a matrix equation in the unknown Taylor coefficients. The Taylor coefficients can be found easily, and hence the Taylor polynomial approach can be applied. This method is also valid for the systems of differential and integral equations. Numerical examples are presented to illusturate the accuracy of the method. The symbolic algebra program Maple is used to prove the results. [ABSTRACT FROM AUTHOR]

Let f , p , q , r be analytical functions in D with complex variables and complex values, where D ? C is a simple connected domain of the complex plane in this study. We give approximative solutions of nonhomogenous ordinary differential equation p ( z ) y (2) ( z )+ q ( z ) y (1) ( z )+ r ( z ) y ( z )= f ( z ) via Taylor matrix method. Then we illustrate these solutions by some given applications. [ABSTRACT FROM AUTHOR]

In this paper, a completely new solution scheme for inverse dynamics, which can be commonly applied in different types of link systems such as open- or closed-loop mechanisms, or ones constituting rigid or flexible link members, is presented. The scheme is developed using the finite element method (FEM), which evaluates the entire system as a continuum with the equation of motion in Cartesian coordinates and in dimension of force. The inverse dynamics is calculated by using a matrix-form relation to the nodal forces obtained by the FEM. The matrix-form equations are divided individually into terms of force, transformation between coordinates and length, which makes the scheme potentially better in terms of applicability and expansibility. The scheme cannot only deal with open- and closed-loop link systems independently, but it can also deal seamlessly with those that gradually change their forms and dynamics. There is also no need to revise the basic numerical algorithm of the scheme, regardless of the stiffness of the constituting link member, i.e. rigid or flexible. The main objective of this paper is to present the extensive ability of the scheme as a unified scheme, by carrying out calculations on several types of rigid and flexible manipulators, along with an application to feed-forward control of a link mechanism which continuously changes its form from an open- to a closed-loop. [ABSTRACT FROM AUTHOR]

An analytic solution to the problem of a plane electromagnetic wave scattering by two parallel elliptic conducting cylinders is presented using an iterative procedure to account for the multiple scattered field between the cylinders. To compute the higher order terms of the scattered fields, the translation addition theorem for Mathieu functions is implemented to express the field scattered by one cylinder in terms of the elliptic coordinate system of the other cylinder in order to impose the boundary conditions. Scattered field coefficients of various orders are obtained and written in matrix form. Numerical results are obtained for the scattered field in the far zone for different axial ratios, electrical separations and angles of incidence. [ABSTRACT FROM AUTHOR]

Collaborative robots have open new ways of designing assembly processes, thanks to their ability to share work space with operators. not only may they support the economical performance, but they can also improve the overall ergonomics. Building on existing work on task allocation problems, the authors study further the collaboration opportunities between operator and robot, namely cooperation phases (type of collaboration where both operator and robot act on the same work piece). This work proposes a new formulation of the related problem, and solutions are sought through heuristics methods, to investigate whether concurrent usage of different collaboration modes delivers better performance. The results indicate that cooperation mode enables higher process performances while controlling ergonomic risks. With a concern for real-life application, it has been applied on a real case study to verify its applicability. [ABSTRACT FROM AUTHOR]