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Aiming at the problems of low accuracy and slow detection rate of existing target detection algorithms for PCB defect detection, and too many parameters of algorithm model leading to the inability to deploy on mobile terminals, a PCB defect detection algorithm based on MSD-YOLOv5 is proposed. Firstly, to ensure both detection accuracy and speed while reducing the model's size,we combine the lightweight MobileNet-v3 network with the CSPDarknet53 network. Further,the attention mechanism is introduced to highlight the important feature channels and weaken the less useful ones, so as to improve the feature extraction ability of the network. Finally, the coupling detection head is replaced with a decoupling detection head, and the defect location information and category information on the PCB are extracted and learned respectively, which solves the problem of highly coupling of different information feature distributions and enhances the generalization ability of the model. We conduct experiments on a publicly available PCB defect dataset from Peking University using this algorithm. The results show that the proposed method reduces the parameters of YOLOv5 model by 46% and improves the detection accuracy by 3.34%. [ABSTRACT FROM AUTHOR]

Coupled multi-physics problems are encountered in countless applications and pose significant numerical challenges. In a broad sense, one can categorise the numerical solution strategies for coupled problems into two classes: monolithic approaches and sequential (also known as split, decoupled, partitioned or segregated) approaches. The monolithic approaches treat the entire problem as one, whereas the sequential approaches are iterative decoupling techniques where the different sub-problems are treated separately. Although the monolithic approaches often offer the most robust solution strategies, they tend to require ad-hoc preconditioners and numerical implementations. Sequential methods, on the other hand, offer the possibility to add and remove equations from the model flexibly and rely on existing black-box solvers for each specific equation. Furthermore, when problems are non-linear, inner iterations need to be performed even in monolithic solvers, making the sequential approaches an even more viable alternative. The cost of running inner iterations to recover the multi-physics coupling could, however, easily become prohibitive. Moreover, the sequential approaches might not converge at all. In this work, we present a general formulation of splitting schemes for continuous operators with arbitrary implicit/explicit splitting, like in standard iterative methods for linear systems. By introducing a generic relaxation operator, we find the conditions for the convergence of the iterative schemes. We show how the relaxation operator can be thought of as a preconditioner and constructed based on an approximate Schur complement. We propose a Schur-based Partial Jacobi relaxation operator to stabilise the coupling and show its effectiveness. Although we mainly focus on scalar-scalar linear problems, most results are easily extended to non-linear and higher-dimensional problems. The schemes presented are not explicitly dependent on any particular discretisation methodologies. Numerical tests (1D and 2D) for two PDE systems, namely the Dual-Porosity model and a Quad-Laplacian operator, are carried out to investigate the practical implications of the theoretical results. [ABSTRACT FROM AUTHOR]

This paper focuses on investigating a second-order time parallel decoupled algorithm for the mixed Stokes/Darcy model. The main objective of this algorithm is to deal with the issue of low computational efficiency in solving the coupling problem directly. Our scheme not only reduces the computation scale through the decoupling method, but also realizes the parallelism in the time direction through parareal method. Furthermore, we implement a second-order spectral deferred correction method to improve accuracy. For some small time step size, we prove the stability and convergence results of the time parallel decoupled algorithm. Finally, we provide three numerical tests to demonstrate the reliability and computational efficiency of our algorithm. [ABSTRACT FROM AUTHOR]

The decoupling of control and forwarding layers brings Software-Defined Networking (SDN) the network programmability and global control capability, but it also poses SDN security risks. The adversaries can use the forwarding and control decoupling character of SDN to forge legitimate traffic, launching saturation attacks targeted at SDN switches. These attacks can cause the overflow of switch flow tables, thus making the switch cannot forward benign network traffic. How to effectively detect saturation attack is a research hotspot. There are only a few graph-based saturation attack detection methods. Meanwhile, the current graph generation methods may take useless or misleading information to the attack detection, thus decreasing the attack detection accuracy. To solve the above problems, this paper proposes TITAN, a bidirecTional forwardIng graph-based saturaTion Attack detectioN method. TITAN defines flow forwarding rules and topology information, and designs flow statistical features. Based on these definitions, TITAN generates nodes of the bi-forwarding graph based on the flow statistics features and edges of the bi-forwarding graph based on the network traffic routing paths. In this way, each traffic flow in the network is transformed into a bi-directional forwarding graph. Then TITAN feeds the above bidirectional forwarding graph into a Graph Convolutional Network (GCN) to detect whether the flow is a saturation attack flow. The experimental results show that TITAN can effectively detect saturation attacks in SDNs with a detection accuracy of more than 97%. [ABSTRACT FROM AUTHOR]

In this work, a polarization rotating surface is designed, analyzed, and applied to the decoupling of ultra-wideband antennas. A method of using dual-size combined rings is proposed to expand the operating bandwidth to 4.8 to 18.2 GHz, and the polarization conversion rate within the entire bandwidth is higher than 99%. Based on the principle of polarization mismatch, placing the polarization rotating surface between ultra-wideband antennas for decoupling can reduce the coupling between antennas by an average of 20 dB within the operating bandwidth. Simulation and experimental results consistently prove its excellent decoupling capabilities and ultra-wide operating bandwidth. [ABSTRACT FROM AUTHOR]

Analysis of cylinders under axisymmetric loading is of great interest as it finds many practical application. In this work, an attempt has been made to solve this problem through variational principle. The variational statement results in a set of coupled partial governing equation and associated boundary conditions. The solution has been derived after systematic decoupling of governing equation, application of separation of variables and use of Frobenius method. The resulting solution as demonstrated is capable of satisfying all the boundary conditions in an exact sense. The accuracy and efficiency of the presented solution have been validated for problems available in the literature and against three-dimensional finite element simulations for isotropic homogeneous material. It is observed that the present solution not only has excellent agreement with three-dimensional finite element analysis but also is generic in nature. [ABSTRACT FROM AUTHOR]

In this work, we introduce a collision model specifically tailored for the simulation of inextensible textiles. The model considers friction, contacts, and inextensibility constraints all at the same time without any decoupling. Self-collisions are modeled in a natural way that allows considering the thickness of cloth without introducing unwanted oscillations. The discretization of the equations of motion leads naturally to a sequence of quadratic problems with inequality and equality constraints. In order to solve these problems efficiently, we develop a novel active-set algorithm that takes into account past active constraints to accelerate the resolution of unresolved contacts. We put to a test the developed collision procedure with diverse scenarios involving static and dynamic friction, sharp objects, and complex-topology folding sequences. Finally, we perform an experimental validation of the collision model by comparing simulations with recordings of real textiles as given by a Motion Capture System. The results are very accurate, having errors around 1 cm for DIN A2 textiles (42 x 59.4 cm) even in difficult scenarios involving fast and strong hits with a rigid object. In this work, we present a novel collision model for inextensible textiles and validate it experimentally through a comparison with real textiles as recorded by a Motion Capture System. In the figure we can see four frames comparing the recorded hitting with a stick of a DIN A2 (42 x 59.4 cm) polyester sheet (left) with its inextensible simulation (right); its average error being 1.44 cm. The recordings are obtained by attaching 20 reflective markers of diameter 3 mm and weight of 0.013 g to the real textile and following their trajectory. On the bottom, we show a full plot of the mean absolute error of the position of each marker with respect to its simulation and with yellow lines we highlight the moments in which the object is in contact with the cloth. Notice that the biggest errors appear not during the hits but just after because of aerodynamic effects. The above simulations, with a 7 × 9 mesh, are two times faster than real-time. Our custom active-set solver is three times faster than a standard interior-point method using the same mesh resolution. • We develop a cloth collision model which results in a coupled resolution of friction, inextensibility, and contact forces. • Self-collisions are modeled in a way that allows considering cloth's thickness without introducing unwanted oscillations. • An active-set solver for the system's integration is developed, which can start from any non-necessarily feasible point. • An empirical validation is performed, with scenarios involving high-friction surfaces and strong hits with a stick. [ABSTRACT FROM AUTHOR]

Summary: We are considering the problem of designing observers for heat partial differential equations (PDEs) that are subject to sensor delay and parameter uncertainty. In order to get finite‐dimensional observers, described by ordinary differential equations (ODE), we develop a design method based on the modal decomposition approach. The approach is extended so that both parameter uncertainty and sensor delay effects are compensated for. To cope more effectively with sensor delay, an output predictor is designed and the online provided output predictions are substituted to the future output values in the observer. To compensate for parameter uncertainty, we design a parameter estimator providing online parameter estimates, which are substituted to the unknown parameters in the observer. The parameter estimator design is made decoupled from the observer gain design by using an appropriate decoupling transformation. Using an analysis of the small‐gain‐theorem type, the whole (state and parameter) estimation error system is shown to be exponentially stable, under well‐defined conditions on the observer dimension, the sensor delay, and signal persistent excitation (PE). [ABSTRACT FROM AUTHOR]

Recently, a signal sorting algorithm based on the congruence transform has been proposed, which is effective in dealing with the staggered Pulse Repetition Interval (PRI) signals. It can effectively sort the staggered PRI signals and obtain the sub-PRI sequence directly without sub-PRI ranking, and it is less affected by interfered pulses and pulse loss. Nevertheless, we find that the algorithm causes pseudo-peaks in the remainder histogram when sorting signals such as sliding PRI, sinusoidal PRI, etc. (collectively referred to as periodic PRI signal in this paper) and pseudo-peaks will cause errors in signal sorting. To solve the issue of pseudo-peaks when sorting periodic PRI signals, an improved sorting algorithm based on congruence transform is proposed. According to the analysis of the congruence characteristics of the periodic PRI signal, a novel method is proposed to identify pseudo-peaks based on the histogram peak amplitude and symmetric difference set. The signal sorting algorithm based on congruence transform is improved to achieve a good sorting effect on periodic PRI signals. Simulation experiments demonstrate that the novel algorithm can effectively sort periodic PRI signals and improve Precall, Pd, and Pf by 6.9%, 5.1%, and 3.2%, respectively, compared to the typical similar algorithms. [ABSTRACT FROM AUTHOR]

In this paper, we intend to utilize the generalized scalar auxiliary variable (GSAV) approach proposed in recent paper (Ju et al., SIAM J. Numer. Anal., 60 (2022), 1905–1931) for the nonlocal coupled sine-Gordon equation to construct a class of fully decoupled, linear, and second-order accurate energy-preserving scheme. The unconditional unique solvability and discrete energy conservation law of the proposed scheme are rigorously discussed, and the unconditional convergence is then proved by the mathematical induction. Particularly, the convergence analysis covers the proposed scheme in multiple dimensions due to the corresponding nonlinear terms satisfy the global Lipschitz continuity straightforwardly. Finally, time evolution of dynamical behavior of the governing equation with different nonlocal parameters are observed, and ample numerical comparisons demonstrate that the proposed scheme manifests high efficiency in long-time computations. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a new method based on a library of chemical reactions for constructing a system of ordinary differential equations from stochastic simulations arising from an agent-based model. The advantage of this approach is that this library respects any coupling between systems components, whereas the SINDy algorithm (introduced by Brunton et al.) treats the individual components as decoupled from one another. Another advantage of our approach is that we can use a non-negative least squares algorithm to find the non-negative rate constants in a very robust, stable and simple manner. We illustrate our ideas on an agent-based model of tumour growth on a 2D lattice. [ABSTRACT FROM AUTHOR]

The metalized film capacitors (MFC) in converter valves are subjected to high-frequency currents under the action of power electronic switching, which will cause large differences in currents among capacitor elements inside MFC and seriously affect the stability of MFC. In this paper, experiments were conducted to measure the current waveforms among 90 elements under impulse, short-circuit discharge and sine waves at different frequencies. The equivalent circuit topology was simplified by using decoupling and controlled source equivalence, and parameters were extracted by electromagnetic calculations combined with experiments. Finally, an equivalent circuit model was established and the current distribution among elements was calculated. Influenced by the reactance of the parasitic inductor and the capacitor element, the frequency range can be divided into 3 regions based on the current distribution characteristics: in the high frequency range (>100 kHz), the current is mainly concentrated on several capacitor elements near the connection terminals. In the middle frequency range (about 10 kHz–100 kHz), the current oscillates between elements and the inductor, resulting in a wavy distribution of current amplitude, strongly influenced by frequency. In the low frequency range (<10 kHz), the current distribution varies very little among 90 elements. These results can support the study of performance evolution, fault analysis and design optimization in MFC. [ABSTRACT FROM AUTHOR]

For the nonlinear parameter‐varying (NPV) model of unmanned surface vehicle with the consideration of the velocities on yaw and surge as well as wave disturbances, a robust H∞$$ {H}_{\infty } $$ control method is proposed based on extended homogeneous polynomial Lyapunov function (EHPLF) to regulate heading for the superior performance on the rapidity, accuracy, and robustness. First, a NPV model of heading error is established to design a general form of a state feedback controller with a robust H∞$$ {H}_{\infty } $$ performance. Second, a Lyapunov matrix with full states and varying parameter is constructed to derive the robust H∞$$ {H}_{\infty } $$ global exponential stability conditions by Euler's homogeneity relation for the NPV system, known as the EHPLF stability conditions. Third, since the EHPLF stability conditions consist of a set of nonlinear coupled inequalities that cannot be directly solved by sum of squares (SOS) toolboxes, they are decoupled with matrix transformations to obtain the EHPLF‐SOS stability conditions, which is solved for the parameters of the state feedback controller. Finally, the simulation results indicate that EHPLF method exhibits a superior performance on dynamic, steady‐state, and robustness. [ABSTRACT FROM AUTHOR]

We prove an (l², L6) decoupling inequality for the parabola with constant (log R)c. In the appendix, we present an application to the sixth-order correlation of the integer solutions to x² + y² = m. [ABSTRACT FROM AUTHOR]

This paper is focused on the numerical approximations of the incompressible magneto-hydrodynamic equations. Our interest is to develop a novel decoupled, linear and unconditional energy stable fully-discrete scheme, which is achieved by the interior penalty discontinuous Galerkin (DG) method for spatial discretization, the stabilizing strategy and implicit-explicit (IMEX) scheme used to handle the nonlinear coupling terms, and a rotational pressure-correction method for the Navier-Stokes equations. We prove the unique solvability, unconditional energy stability and optimal error estimates of the proposed scheme rigorously. We further present several numerical examples to demonstrate the accuracy, stability, and efficiency of the proposed scheme numerically. [ABSTRACT FROM AUTHOR]

In this article, we propose a fully decoupled first-order time discrete scheme for the unsteady thermally coupled magnetohydrodynamics (MHD) equations with variable density, which is a large nonlinear strongly coupled system consisting of incompressible Navier-Stokes equations with variable density, heat equation and Maxwell equations. The proposed scheme is highly efficient because only the linearised subproblems need to be solved at the discrete level. Furthermore, unconditional stability analysis is established which is a vital issue in the field of multiphysics. We also construct and implement a fully discrete scheme based on conforming finite elements in space. Several 2D/3D numerical tests are conducted to confirm the efficiency and accuracy of the developed scheme with large density differences. [ABSTRACT FROM AUTHOR]

Lighter-than-air (LTA) aerial vehicles such as airships and aerostats can be found in various strategic and commercial applications, primarily due to their capability to hover and stealth. The mathematical model of these vehicles helps in understanding their complex dynamics and designing and developing proper stabilisation systems for them. Stability derivatives have been used for developing mathematical models for heavier-than-air aerial vehicles since their introduction. This paper presents a methodology to develop a mathematical model of an aerostat based on stability derivatives. One of the major contributions of this study is the estimation of aerostat's added mass terms expressed as longitudinal stability derivatives due to acceleration of the longitudinal motion variables. A longitudinally decoupled linear mathematical model of a single-tethered aerostat using stability derivatives is investigated in this study. A computational fluid dynamics (CFD)-based analysis of the 3D model of the vehicle is used to obtain the stability derivatives. The methodology presented considers the aerostat and tether models separately before coupling them to create the full model. The stability derivative analysis is carried out using ANSYS Fluent, and the coupled tethered aerostat model is investigated using MATLAB 2020. The negative pitch angle of the aerostat is caused by the selection of the pitching centre as the aerostat centre of volume instead of the tether confluence point. The tension force on the tether, which is proportional to the wind velocity, and aerostat velocity components are found to be stabilised within 200–400 s. [ABSTRACT FROM AUTHOR]

We construct new three-family N = 1 supersymmetric Pati–Salam models from intersecting D6-branes with original gauge group U (4) C × USp (2) L × U (2) R on a Type IIA T 6 / (Z 2 × Z 2) orientifold. We find that replacing a U (2) with a USp (2) group severely restricts the number of three-generation supersymmetric models such that there are only five inequivalent models. Exchanging the left and right sectors, we obtain five dual models with gauge group U (4) C × U (2) L × USp (2) R . These ten models have different gauge coupling relations at string scale. The highest wrapping number is 4, and one of the models contains no filler O6-planes. Moreover, we discuss in detail the particle spectra, the composite particles through strong coupling dynamics, and the exotic particle decouplings. Also, we study how to realize the string-scale gauge coupling relations in some models. [ABSTRACT FROM AUTHOR]

We introduce a notion of residual diffeomorphism covariance in quantum Kantowski–Sachs (KS) describing the interior of a Schwarzschild black hole. We solve for the family of Hamiltonian constraint operators satisfying the associated covariance condition, as well as parity invariance, preservation of the Bohr Hilbert space of the Loop Quantum KS and a correct (naïve) classical limit. We further explore the imposition of minimality for the number of terms and compare the solution with those of other Hamiltonian constraints proposed for the Loop Quantum KS in the literature. In particular, we discuss a lapse that was recently commonly chosen due to the resulting decoupling of the evolution of the two degrees of freedom and the exact solubility of the model. We show that such a choice of lapse can indeed be quantized as an operator that is densely defined on the Bohr Hilbert space and that any such operator must include an infinite number of shift operators. [ABSTRACT FROM AUTHOR]

The non-decoupling effects of heavy scalars and vector fields play an important role in the indirect search for Beyond the Standard Model (BSM) physics at the LHC. By exploiting some new differential equations for the 1-PI amplitudes, we show that such non-decoupling effects are absent for quite a general class of effective field theories involving dimension six two-derivative and dimension eight four-derivative operators, once the resummation in certain BSM couplings is taken into account and some particular regimes of the relevant couplings are considered. [ABSTRACT FROM AUTHOR]

The traditional structural performance may be seriously degraded due to applied indeterministic cases. A novel framework for robust topology optimization of truss-like continuum considering uncertain loads is presented. The robust optimization formula is constructed as minimizing the weighted sum of expectancy and standard variance of structural compliance with volume constraints. In this framework, both the magnitude and direction of applied loads are uncertain and independent. Truss-like continuum provides the topology optimal structure theoretically. Based on the classic truss-like optimization method, the statistical moments of compliance are accurately evaluated utilizing a bivariate cloud model tool. An effective strategy based on linear decoupling is reported to largely reduce the total number of finite element analysis. The optimization is achieved with gradient-based mathematic programming. Several numerical examples demonstrate a better structural robust performance obtained by the proposed algorithm than the traditional one. [ABSTRACT FROM AUTHOR]

Minimax problems have recently attracted a lot of research interests. A few efforts have been made to solve decentralized nonconvex strongly-concave (NCSC) minimax-structured optimization; however, all of them focus on smooth problems with at most a constraint on the maximization variable. In this paper, we make the first attempt on solving composite NCSC minimax problems that can have convex nonsmooth terms on both minimization and maximization variables. Our algorithm is designed based on a novel reformulation of the decentralized minimax problem that introduces a multiplier to absorb the dual consensus constraint. The removal of dual consensus constraint enables the most aggressive (i.e., local maximization instead of a gradient ascent step) dual update that leads to the benefit of taking a larger primal stepsize and better complexity results. In addition, the decoupling of the nonsmoothness and consensus on the dual variable eases the analysis of a decentralized algorithm; thus our reformulation creates a new way for interested researchers to design new (and possibly more efficient) decentralized methods on solving NCSC minimax problems. We show a global convergence result of the proposed algorithm and an iteration complexity result to produce a (near) stationary point of the reformulation. Moreover, a relation is established between the (near) stationarities of the reformulation and the original formulation. With this relation, we show that when the dual regularizer is smooth, our algorithm can have lower complexity results (with reduced dependence on a condition number) than existing ones to produce a near-stationary point of the original formulation. Numerical experiments are conducted on a distributionally robust logistic regression to demonstrate the performance of the proposed algorithm. [ABSTRACT FROM AUTHOR]

Summary: This article concerns the problem of event‐protocol‐based asynchronous fault detection filtering design for discrete‐time fuzzy singular semi‐Markovian jump systems subjected to system parameters uncertainties, unmatched one‐sided Lipschitz nonlinearities and multi‐cyber‐attacks. First, a well‐designed model structure is proposed to integrate two dynamic quantizers and an improved dynamic event‐triggered protocol into a unified framework to reduce the amount of data in the network transmission and rationalize the use of limited network communication bandwidth resources. Especially, the event‐triggering threshold parameter can be continuously adjusted over the time based on the fluctuation of the network signal. Second, a novel triple‐cyber‐attacks platform is established, of which including random deception attacks, random replay attacks and aperiodic DoS attacks. And with help of the extended decoupling strategy and iterative techniques, the co‐design conditions of the stochastic admissibility with a ℘˘ level of ℋ∞$$ {\mathscr{H}}_{\infty } $$ performance are derived for the fault filtering error systems. Finally, two examples are provided to demonstrate the effectiveness and feasibility of the proposed algorithm. [ABSTRACT FROM AUTHOR]

Economic progress has been founded on environmental pressure by generating all types of environmental harm, such as an increase in greenhouse gases in the atmosphere and significant climate change, which has forced people to reflect. Building a people-oriented, comprehensive, coordinated system to compile experience and lessons assists the government in formulating appropriate policies according to the meaning of the scientific development viewpoint. Based on the above, this research designs Cost–Benefit Decision Tree (CBDT) Algorithm for the economic protection development level using a Decision Tree (DT) and Ensemble Algorithm. In the design of ML Algorithm, this research work initially introduces the Decision Tree model for economic protection evaluation by emphasizing its value as a basic machine-learning framework for fully examining many aspects of economic protection development. Second, it investigates the critical role of Ensemble Algorithms, such as Random Forest in augmenting the capabilities of DT. Third, the paper focuses on the development of a complete Economic Protection Evaluation Index System using the DT Algorithm. To provide a robust, scientifically sound, and practicable framework for evaluating economic protection, this approach integrates scientificity, comparability, systematization, hierarchy, relative decoupling, and data availability principles. Finally, the study constructs the suggested ML Algorithm using the insights from the preceding parts. This algorithm combines the Decision Tree and Random Forest models to generate a single, effective tool for evaluating economic development levels. The experimental findings suggest that the proposed hybrid assessment technique is effective across several dimensions. The proposed CBDT demonstrated its capacity to adapt to changing data circumstances in evaluating low-carbon efficiency using real-world data from 30 major Chinese cities. Furthermore, the algorithm regularly beats rival techniques regarding efficiency improvements, with an average improvement of 12.5% across all cities. Notably, it outperforms other algorithms regarding computational efficiency, with a quicker execution time and an exceptional accuracy rate of 93.2%. The proposed ML Algorithm improves decision-making in the economic protection development level field by effectively balancing cost and benefit considerations. It will improve accuracy and efficiency to outperform existing approaches, thereby advancing economic protection evaluation and decision-making processes in this domain. [ABSTRACT FROM AUTHOR]

In this paper, we establish local well-posedness for the Zakharov system on T d , d ≥ 3 in a low regularity setting. Our result improves the work of Kishimoto (J Anal Math 119:213–253, 2013). Moreover, the result is sharp up to ε -loss of regularity when d = 3 and d ≥ 5 as long as one utilizes the iteration argument. We introduce ideas from recent developments of the Fourier restriction theory. The key element in the proof of our well-posedness result is a new trilinear discrete Fourier restriction estimate involving paraboloid and cone. We prove this trilinear estimate by improving Bourgain–Demeter's range of exponent for the linear decoupling inequality for paraboloid (Bourgain and Demeter in Ann Math 182:351–389) under the constraint that the input space-time function f satisfies supp f ^ ⊂ { (ξ , τ) ∈ R d + 1 : 1 - 1 N ≤ | ξ | ≤ 1 + 1 N , | τ - | ξ | 2 | ≤ 1 N 2 } for large N ≥ 1 . [ABSTRACT FROM AUTHOR]

A photovoltaic (PV) maximum power point tracking (MPPT) converter behaves as a decoupling stage that dynamically tracks the peak power of a PV generator with an output characteristic curve that is nonlinear and changes with respect to solar irradiation and cell temperature. Depending on different voltage transfer functions and application requirements, the classical MPPT converter topologies include buck, boost, buck-boost, flyback, etc. In this paper, an improved Watkins–Johnson (WJ) topology is added to the family of MPPT converters. This improved topology has the merits of a simple circuit structure, power switches that are easy drive, synchronous mode capability, and high efficiency at a marginal duty cycle. To balance the tracking speed and tracking stability of the WJ topology, key issues including the perturbation period and perturbation amplitude have been resolved by means of small-signal modeling and an analysis according to the PV model parameters and converter electrical elements. An experimental prototype has been designed, constructed, and utilized to verify the feasibility of the proposed concept. [ABSTRACT FROM AUTHOR]

Here, we consider the phase field transition system (a nonlinear system of parabolic type) introduced by Caginalp to distinguish between the phases of the material that are involved in the solidification process. We start by investigating the solvability of such boundary value problems in the class W p 1 , 2 (Q) × W ν 1 , 2 (Q) . One proves the existence, the regularity, and the uniqueness of solutions, in the presence of the cubic nonlinearity type. On the basis of the convergence of an iterative scheme of the fractional steps type, a conceptual numerical algorithm, alg-frac_sec-ord-varphi_PHT, is elaborated in order to approximate the solution of the nonlinear parabolic problem. The advantage of such an approach is that the new method simplifies the numerical computations due to its decoupling feature. An example of the numerical implementation of the principal step in the conceptual algorithm is also reported. Some conclusions are given are also given as new directions to extend the results and methods presented in the present paper. [ABSTRACT FROM AUTHOR]

The aim of this work is to present a model reduction technique in the framework of optimal control problems for partial differential equations. We combine two approaches used for reducing the computational cost of the mathematical numerical models: domain–decomposition (DD) methods and reduced–order modelling (ROM). In particular, we consider an optimisation–based domain–decomposition algorithm for the parameter–dependent stationary incompressible Navier–Stokes equations. Firstly, the problem is described on the subdomains coupled at the interface and solved through an optimal control problem, which leads to the complete separation of the subdomain problems in the DD method. On top of that, a reduced model for the obtained optimal–control problem is built; the procedure is based on the Proper Orthogonal Decomposition technique and a further Galerkin projection. The presented methodology is tested on two fluid dynamics benchmarks: the stationary backward–facing step and lid-driven cavity flow. The numerical tests show a significant reduction of the computational costs in terms of both the problem dimensions and the number of optimisation iterations in the domain–decomposition algorithm. • Optimisation–based domain–decomposition algorithm for computational fluid dynamics. • Gradient–based optimisation algorithm for decoupling of the subdomains solves. • Projection–based reduced order model for parameterised Navier–Stokes problem. • Significant reduction in space dimension and optimisation iterations. [ABSTRACT FROM AUTHOR]

High-symmetry transition-metal dichalcogenides (TMDs) have garnered substantial attention in the fields of sensors, optoelectronics, and valleytronics. However, the inherent C3 rotational symmetry of TMDs engenders highly isotropic properties, impeding their further technological progress. To overcome this limitation, we embarked on a study to investigate the effects of isotropic/anisotropic heterostructures engineering on WS2, aiming to break its C3 rotational symmetry. In this work, we designed and fabricated heterostructures composed of WS2 and ReS2 layers. Our comprehensive investigations revealed a remarkable emergence of anisotropic characteristics in excitons originating from the WS2 layers within the engineered WS2/ReS2 heterostructures. Moreover, we observed an enhancement in the valley polarizations of WS2 layers within the heterostructures, which is attributed to the reduced intervalley scattering facilitated by the WS2/ReS2 heterostructure configuration. This observation indicates the potential for leveraging heterostructure engineering to tailor and optimize anisotropic devices, thereby opening promising avenues for future applications in various technological domains. [ABSTRACT FROM AUTHOR]

Because of the control complexity of voltage source converters (VSCs), transient stability analysis of multi-VSC parallel systems is challenging, and there are still no effective methods to solve this problem. Inspired by the decoupling principle and combined with the normal form method, an innovative coupling-factor-based nonlinear decoupling (CFND) method is proposed. According to the coupling factors that can be used to evaluate the nonlinear coupling degree among different state variables, the CFND method approximately transforms a high-order nonlinear multi-VSC parallel system into multiple decoupled low-order modes. Thus, the transient stability of the original high-order multi-VSC system can be reflected indirectly by the mature inversing trajectory method and the phase plane method. The CFND method has universality, flexibility, and insensitivity to system order, and no need to construct corresponding Lyapunov functions for different nonlinear systems, breaking through the inherent limitations of traditional analysis methods. Furthermore, this paper derives a reduced-order large-signal model and the corresponding truncated model for a single VSC grid-connected system. The effectiveness of the reduced-order model is verified through simulation waveforms and ROAs partitioning. Subsequently, a generalized model of the multi-VSC grid-connected system is developed. Finally, taking the grid-connected system with three VSCs as an example, the proposed CFND method is used to analyze typical operation cases, and the conclusions of transient stability analysis are verified using the hardware-in-loop (HIL) experiments. [ABSTRACT FROM AUTHOR]

We study a decoupling limit of M-theory where the three-form gauge potential becomes critical. This limit leads to nonrelativistic M-theory coupled to a non-Lorentzian spacetime geometry. Nonrelativistic M-theory is U-dual to M-theory in the discrete light cone quantization, a non-perturbative approach related to the Matrix theory description of M-theory. We focus on the compactification of nonrelativistic M-theory over a two-torus that exhibits anisotropic behaviors due to the foliation structure of the spacetime geometry. We develop a frame covariant formalism of the toroidal geometry, which provides a geometrical interpretation of the recently discovered polynomial realization of SL(2 , ℤ) duality in nonrelativistic type IIB superstring theory. We will show that the nonrelativistic IIB string background fields transform as polynomials of an effective Galilean "boost velocity" on the two-torus. As an application, we construct an action principle describing a single M5-brane in nonrelativistic M-theory and study its compactification over the anisotropic two-torus. This procedure leads to a D3-brane action in nonrelativistic IIB string theory that makes the SL(2 , ℤ) invariance manifest in the polynomial realization. [ABSTRACT FROM AUTHOR]

The global demand of electrical power has increased enormously due to various reasons such as fast-changing and challenging technologies, climatic change, economic growth, and lifestyle of mankind. Due to global warming issues and the depletion of conventional sources of power generation, the utilization of renewable energy sources has drastically increased. So, many challenges exist in integrating the microgrid with AC grid and load. The alternative arm converter (AAC) is among the most innovative converter topologies used in high voltage direct current (HVDC) applications. This research work presents a new control strategy to generate pulses to trigger the switches in the AAC in a proper sequence to obtain a smooth output waveform. The AAC output is controlled by implementing various controllers such as the proportional-integral-derivative (PID) controller, fractional order PID (FOPID) controller, and FOPID controller tuned by metaheuristic algorithm-bacterial foraging optimization technique (BFOT). Also, a comparative analysis is performed based on the spectral analysis of the output voltage obtained. In comparison to other controllers, the FOPID controller optimized by the bacterial foraging optimization technique (BFOT) produced the least total harmonic distortion (THD) of the AAC output voltage. In addition, this paper also discusses about the performance and analysis on the design of an energy management system (EMS) to optimally utilize the energy sources such as PV system, wind system, and battery based on their availability which feed the AAC. The energy management system controls the entire integrated system in association with an integrated CUK-SEPIC converter to fulfil the load demand at the point of common coupling, either from the microgrid or the AC grid. A nine-level AAC model is designed integrating the microgrid, grid, and industrial loads with an energy management system using MATLAB/Simulink. The performance parameters of the entire model are analysed at every stage to provide stabilized output to meet the load demand. [ABSTRACT FROM AUTHOR]

This paper presents an efficient parallel computing strategy to solve large-scale structural vibration problems. The proposed approach utilises a novel direct method that operates using simplex-shaped space-time finite elements and allows for the direct decoupling of variables during the assembly of global matrices. The method uses consistent stiffness, inertia and damping matrices and deals with non-symmetric matrices. One significant advantage of this approach is that the computational cost remains unaffected by the bandwidth of the matrix in the traditional sense because only non-zero coefficients are retained. The speed of computations demonstrates a noticeable increase as the number of nodes and the problem's dimensionality grow. To demonstrate the effectiveness of the parallel space-time approach, a comparison with a sequentially executed code was conducted. The results indicate that the proposed method enables calculations at least 20 times faster than those achieved using the classical finite element method. Furthermore, the parallelisation algorithm was successfully implemented to solve a dynamics problem involving a large-scale, three-dimensional railway structure subjected to a moving load. Remarkably, the problem was solved in a reasonable amount of time using a relatively low-cost personal computer. • Strategy allows efficient parallel computing for large scale structural problems. • Direct method uses simplex-shaped space-time finite elements. • Variables are decoupled while assembling global matrices. • Computational cost is independent of the bandwidth. • Simulations of travelling load problems exhibit twenty times faster computations. [ABSTRACT FROM AUTHOR]

• The proposed element leads to equivalently analytic solutions at nodes with second-order accuracy. • The concentrated follower load and its load stiffness matrix incorporate an arbitrary load-inclination angle. • Computational time is reduced when considering the load stiffness matrix of the bending moment. • The distributed load presents nonlinearly-varying loading magnitude along the beam centerline. • The proposed element outperforms the B22 element of ABAQUS when solving pressure loading cases. Follower loads interact with the object's configuration, and the two are unknown variables in geometrically nonlinear analysis. This work aims to solve the large deformation of slender beams under follower loads via the Bernoulli–Euler beam element of absolute nodal coordinate formulation. The second-order approximate function of the beam centerline is utilized to model the beam configuration and the Frenet frame. The elastic force vector and its tangent stiffness matrix are formulated following the decoupling elastic line approach. The constraint of adjacent elements is imposed using Lagrange multipliers. The exact kinematics characteristics of typical follower loads are demonstrated; sequentially, the external force vectors and the load stiffness matrices are rigorously derived based on the configuration and the Frenet frame modelled by the second-order approximate function. Benchmark problems of straight and curved beams under different follower loads are solved, wherein the accuracy and efficiency of the proposed approach are validated as compared to relevant analytical and numerical solutions. It is found that the proposed element yields equivalently analytical nodal solutions, including position, rotation and curvature; considerably fewer proposed elements are used as compared with other finite element methods; the load stiffness matrix of the bending moment raises computational efficiency of the proposed element; the obtained solutions are more accurate than that of the B22 element of ABAQUS when solving pressure loading cases. By further extending the proposed approach, it can enable the unveiling of the spatio-temporal evolution characteristic of slender structures and follower loads from the equivalently analytical perspective. [ABSTRACT FROM AUTHOR]

Graph Convolutional Network (GCN) have been widely used in the field of skeleton-based action recognition and have achieved exciting results. Introducing attention mechanism in the process of extracting skeleton features has always been a hot spot in GCN-related research. In this article, we design a new graph convolutional network, which combines the advanced decoupling graph convolutional network (DC-GCN) with spatial, temporal, channel (STC) series attention module and adaptive normalization (AN). The STC attention module helps the network tend to extract important information from skeleton features. In addition, in order to improve the adaptability of the normalization method to GCN, we design the AN module instead of the BN module, which can train the weights of different normalization methods, so that each normalization layer in the network adopts the most suitable normalization operation. The experimental results show that the accuracy of our method is competitive with the state-of-the-art action recognition methods. [ABSTRACT FROM AUTHOR]

We study how the black hole complementarity principle can emerge from quantum gravitational dynamics within a local semiclassical approximation. Further developing and then simplifying a microstate model based on the fragmentation instability of a near-extremal black hole, we find that the key to the replication (but not cloning) of infalling information is the decoupling of various degrees of freedom. The infalling matter decouples from the interior retaining a residual time-dependent quantum state in the hair which encodes the initial state of the matter non-isometrically. The non-linear ringdown of the interior after energy absorption and decoupling also encodes the initial state, and transfers the information to Hawking radiation. During the Hawking evaporation process, the fragmented throats decouple from each other and the hair decouples from the throats. We find that the hair mirrors infalling information after the decoupling time which scales with the logarithm of the entropy (at the time of infall) when the average mass per fragmented throat (a proxy for the temperature) is held fixed. The decoding protocol for the mirrored information does not require knowledge of the interior, and only limited information from the Hawking radiation, as can be argued to be necessitated by the complementarity principle. We discuss the scope of the model to illuminate various aspects of information processing in a black hole. [ABSTRACT FROM AUTHOR]

Model-based decoupling control methods have been widely used in the register control of Roll-to-Roll (R2R) printing systems due to their advantage in dealing with couplings. While they achieve a certain decoupling effect, their registrations are influenced by the accuracy of the model and decoupling compensation. In this paper, a hybrid model is presented to calculate an appropriate compensation to eliminate the complex velocity-error relations in the R2R system, which consists of a general register error model and a data-based supplement model. Then, an adaptive decoupling control (ADC) method is proposed, in which the feedback gains are determined by solving a Riccati equation. The effectiveness of the hybrid model is validated by experiments, while the superior performance of the ADC is demonstrated by simulations. The results indicate that the hybrid model is more accurate than the general model and ADC method can rapidly reduce the register errors into a range of ±10μm. In addition, simulated comparisons of ADC, direct decoupling proportional differential (DDPD), and improved DDPD control methods also show that the ADC owns the highest register precision and smoothest control signal. [ABSTRACT FROM AUTHOR]

Summary: This paper studies the stability analysis and stabilization synthesis problems for a class of continuous‐time jump systems with hidden system modes. To precisely model the switching signals of the considered systems, a novel definition of continuous‐time hidden semi‐Markov process is proposed based on the notions of emission probability and time varying dual‐index transition rate. By virtue of such definition, a dual‐index Lyapunov function is utilized to derive the sufficient stability conditions of the considered systems. By adopting a technology that can decouple the nonlinear terms in the above conditions, the numerically testable existence conditions of the controller for the resulting stabilizing systems are presented. An example is given to illustrate the effectiveness of our results. [ABSTRACT FROM AUTHOR]

Summary: A controller design method based on effective open‐loop transfer function (EOTF) and internal model control (IMC) is proposed for square multivariable systems with uncertain parameters. In this paper, two equivalent substitutions are used to deal with the multivariable system with uncertain parameters. In the first equivalent substitution, the EOTF method is used to solve the coupling problem of the system. In order to prevent the interval explosion problem of parameters, the affine algorithm is adopted in the decoupling process to determine the value region of system parameters. Then, the multivariable system with uncertain parameters is transformed into a set of single‐variable system with uncertain parameters. The second equivalent substitution is based on Kharitonov's theorem to process every single variable system with uncertain parameters and replace it by a set of boundary models. Meanwhile, in order to ensure that the tuning controller can not only make the system stable but also meet a certain degree of robustness, based on the idea of IMC, the maximum sensitivity is introduced to design the PID controller. Finally, numerical simulation results are given to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper considers the wireless powered mobile edge computing combining wireless power transmission (WPT) and mobile edge computing, where the hybrid access point (HAP) uses multiple radio beams to charge multiple wireless devices (WDs) and WD adopts the binary offloading mode to offload computation workload to HAP via FDMA. It is aimed to maximize the sum computation rate (SCR) of WDs by jointly optimizing the binary offloading decision, transmit power of each radio beam, and WPT duration. Due to the strong coupling between the offloading decision and other optimization variables, the SCR maximization is formulated as a mixed integer nonlinear programming problem. To address this challenging problem, an online DRL‐based decoupling optimization algorithm is proposed. Specifically, the original problem is first split into a top‐problem of optimizing binary offloading decision and a sub‐problem of optimizing transmit powers and WPT duration under given offloading decision. Then a self‐learning DRL framework is designed to output the near‐optimal offloading decisions. Finally, for the sub‐problem, based on the Lagrangian dual theory, an efficient approach to fast obtain the closed‐form expression of the optimal solution is proposed. The simulation results show that the proposed DRL‐based algorithm can achieve the near‐maximal SCR with low computational complexity. [ABSTRACT FROM AUTHOR]

The theoretical model of a Galfenol cantilever energy harvester is investigated for vibration energy harvesting. Compared with the numerical solution, the analytical solution can better capture the intrinsic effects of the physical parameters on the performance of the harvester. In this work, an electromechanical coupled distributed-parameter model of the Galfenol cantilever energy harvester is established based on Hamilton's principle, linear constitutive equations of magnetostrictive material, and Faraday's law of electromagnetic induction. The definitions and expressions of the electric damping and modified frequency are proposed due to the electromechanical coupling. The explicit analytical expressions of the average harvested power across the load resistance and tip vibration displacement of the Galfenol energy harvesting model are derived using the methods of Galliakin decomposition and electromechanical decoupling. The accuracy of the derived analytical results is verified by the experimental data and numerical solutions. The vibration response and energy harvesting performance of the Galfenol energy harvesting model are investigated by varying the excitation frequency, external resistance, and excitation acceleration amplitude. The analytical results show that, with the increase of the external load resistance and excitation frequency, the harvested power increases first and then decreases, indicating the existence of the optimal resistance and excitation frequency. From the explicit analytical expressions of the average harvested power, the optimal external load resistance or excitation frequency could be easily found to achieve the maximum harvested power for any fixed excitation frequency or external load resistance. The concept of proposing the electric damping and modified frequency for the Galfenol cantilever energy harvester simplifies the solution process for the output performances benefiting from the exact relationship between the output performances and the electromechanical coupling parameter derived in this work. [ABSTRACT FROM AUTHOR]

Spin-crossover (SCO) materials exhibit thermal conversion of their electronic state from low (LS) to high (HS) spin state, which also involves both intra- and inter-molecular structural reorganisations within the crystal. The occurrence of coupled SCO and symmetry-breaking (SB), also responsible for structural reorganisations, is a current topic of interest because it can generate exotic behaviours such as unsymmetric hysteresis loops, stepwise evolution of the spin conversion, or sequences of phase transitions. Here we study the coupling and decoupling of SCO and SB during the thermal conversion of the prototypical [Fe(ptz)6](BF4)2 compound diluted in the isostructural ruthenium host lattice [Ru(ptz)6](BF4)2. We show that the [Ru0.35Fe0.65(ptz)6](BF4)2 system undergoes a SB between the high-spin high symmetry (HShs) phase (R3¯ space group) and the low-spin low symmetry (LSls) phase (P1¯ space group). We present a structural analysis of the ferroelastic R3¯ → P1¯ phase transition and highlight the structural SB signatures. We also study the metastable low-spin high symmetry (LShs) phase (R3¯ space group) reached upon fast cooling. In the framework of the Landau theory of phase transition adapted by Collet, and considering the elastic coupling between SCO and SB, we discuss the structural distortion between the HShs, LShs, and LSls phases and explain the metastable nature of the LShs phase. [ABSTRACT FROM AUTHOR]

Regime-switching models have been heavily studied recently, as they have some clear advantages of over other non-constant volatility model to resolve the so-called smirk effect displayed when constant volatility models are used to price financial derivatives such as options. However, due to the increased model complexity, the associated computational effort usually increases as well, particularly when they are used to price American-style options. In this paper, a novel computational approach based on integral equations is presented. A distinctive feature of our approach, in comparison with other numerical approaches, is that the coupled partial differential equations (PDEs) in a PDE system have been decoupled in the Fourier space, resulting in a completely decoupled integral equation for each economical states, and thus has greatly reduced computational effort. Some examples with preliminary results for a two-state regime-switching model are used to demonstrate our approach. [ABSTRACT FROM AUTHOR]

A linear-quadratic optimal control problem for a forward stochastic Volterra integral equation (FSVIE) is considered. Under the usual convexity conditions, open-loop optimal control exists, which can be characterized by the optimality system, a coupled system of an FSVIE and a type-II backward SVIE (BSVIE). To obtain a causal state feedback representation for the open-loop optimal control, a path-dependent Riccati equation for an operator-valued function is introduced, via which the optimality system can be decoupled. In the process of decoupling, a type-III BSVIE is introduced whose adapted solution can be used to represent the adapted M-solution of the corresponding type-II BSVIE. Under certain conditions, it is proved that the path-dependent Riccati equation admits a unique solution, which means that the decoupling field for the optimality system is found. Therefore, a causal state feedback representation of the open-loop optimal control is constructed. An additional interesting finding is that when the control only appears in the diffusion term, not in the drift term of the state system, the causal state feedback reduces to a Markovian state feedback. [ABSTRACT FROM AUTHOR]

In this work, we present an anisotropic generalization of the Buchdahl static stellar model by implementing the method of extended gravitational decoupling and further requirement of vanishing complexity (Herrera, Phys Rev D 97:044010,2018). Starting off with a general spherically symmetric static metric with two unknown gravitational potentials, we impose the condition of vanishing complexity which then reduces the problem to a single‐generating metric function [Contreras and Stuchlik, Eur. Phys. J. C (2022) 82:706]. The Buchdahl ansatz is then employed to obtain the complete gravitational behavior of the isotropic seed solution. The method of extended gravitational decoupling is thereafter utilized to obtain an anisotropic counterpart of the Buchdahl perfect gravitating sphere. We subject our solution to rigorous physical tests to ensure that it serves as a viable candidate for compact objects such as neutron stars as well as pulsars. We show that the decoupling parameter plays a crucial role in determining the stability and regularity of several key physical features of the entire stellar model. A novel finding of our investigation is the energy exchange between the seed solution and the secondary source which we show is sensitive to the decoupling parameter. In addition, it has also been shown that the direction of energy flow depends on the radial distance of the shell from the center of the stellar configuration. [ABSTRACT FROM AUTHOR]

In this work, we generate curved Lorentzian manifolds from a flat Minkowskian space–time, through the Gravitational Decoupling by the Minimal Geometric Deformation method interpreting the decoupling sector as a generator of curvature and matter distribution. In particular, we obtain some new wormhole geometries by imposing either physically relevant equations of state or certain physically–motivated geometric constraints. These solutions are analyzed in detail. For all these solutions, we study the associated energy conditions, the geometric behavior and construct their embedding diagrams. [ABSTRACT FROM AUTHOR]

In this paper, we consider a non‐static spherical geometry and formulate its extension for the case of anisotropic matter configuration through minimal gravitational decoupling in f(R,T)$f(\mathbb {R},\mathbb {T})$ theory. We apply a particular transformation only on the radial metric function that divides the modified field equations into two distinct sectors corresponding to their parent (original and additional) sources. The unknowns in the first (isotropic) set are reduced by taking the Friedmann‐Lemaitre‐Robertson‐Walker cosmic model. We then obtain the isotropic solution by employing a linear equation of state and power‐law form of the scale factor. The other set involves the decoupling function and components of an extra source, therefore we adopt a density‐like constraint to close it. Finally, we analyze the role of this modified gravity and the decoupling parameter on three different eras of the cosmos by graphically observing the developed extended solution. It is concluded that the resulting solutions fulfill all the physical requirements only for the matter and radiation‐dominated eras. [ABSTRACT FROM AUTHOR]

In this article, we mainly consider a first-order decoupling penalty method for the 2D/3D time-dependent incompressible magnetohydrodynamic (MHD) equations in a convex domain. This method applies a penalty term to the constraint "divu = 0," which allows us to transform the saddle point problem into two small problems to solve. The time discretization is based on the backward Euler scheme. Moreover, we derive the optimal error estimate for the penalty method under semi-discretization with the relationship 휖 = O(Δt). Finally, we give abundant of numerical tests to verify the theoretical result and the spatial discretization is based on Lagrange finite element. [ABSTRACT FROM AUTHOR]

Nuclear long-lived spin states represent spin density operator configurations that are exceptionally well protected against spin relaxation phenomena. Their long-lived character is exploited in a variety of Nuclear Magnetic Resonance (NMR) techniques. Despite the growing importance of long-lived spin states in modern NMR, strategies for their identification have changed little over the last decade. The standard approach heavily relies on a chain of group theoretical arguments. In this paper, we present a more streamlined method for the calculation of such configurations. Instead of focusing on the symmetry properties of the relaxation superoperator, we focus on its corresponding relaxation algebra. This enables us to analyze long-lived spin states with Lie algebraic methods rather than group theoretical arguments. We show that the centralizer of the relaxation algebra forms a basis for the set of long-lived spin states. The characterization of the centralizer, on the other hand, does not rely on any special symmetry arguments, and its calculation is straightforward. We outline a basic algorithm and illustrate advantages by considering long-lived spin states for some spin-1/2 pairs and rapidly rotating methyl groups. [ABSTRACT FROM AUTHOR]