Scalar Method Research Articles

Differential graphical game‐based multi‐agent tracking control using integral reinforcement learning

AbstractThis paper studies the cooperative tracking control problem of interacted multi‐agent systems (MASs) under undirected communication. Based on differential graphical game theory, the MAS tracking control problem is formulated as an infinite horizon cooperative differential graphical game‐theoretic tracking control framework, where a multi‐objective optimization problem is designed and then cast into a Pareto‐equivalent single‐objective optimization problem using a scalarization method. Necessary and sufficient conditions for the existence of the Pareto‐optimal strategy to the game theoretic tracking control are established, where it has been proven that the solution to the integral Bellman optimality equation leads to Pareto‐optimal strategy. Then, an off‐policy integral reinforcement learning scheme to find optimal control strategy using a pure data‐driven manner is developed, which consumes less computation efforts than the traditional learning scheme. Simulated results are conducted to validate the effectiveness of the proposed game and IRL‐based tracking control method.

The Mapping of Research on Workplace Management and Control Using a SCALAR Method and Bibliometric DSS

The Mapping of Research on Workplace Management and Control Using a SCALAR Method and Bibliometric DSS

Three-dimensional finite-memory quasi-Newton inversion of the magnetotelluric based on unstructured grids

Abstract Simulation optimization of complex geological bodies is a necessary means to improve inversion accuracy and computational efficiency; thus, inversion of magnetotelluric (MT) based on unstructured grids has become a research hotspot in recent years. This article realizes the three-dimensional (3D) finite element forward modeling of MT based on the magnetic vector potential-electric scalar potential method, using unstructured grids as the forward modeling grid, which improves computational efficiency. The inversion uses the limited-memory Broyden–Fletcher–Goldfarb–Shanno (LBFGS) method, and in the process of calculating the objective function gradient, the quasi-forward method is used to avoid solving the Jacobian matrix, which has the advantages of requiring small storage space and fast computational efficiency. Finally, the 3D LBFGS inversion algorithm of MT based on unstructured grids was realized, and the inversion studies of classic and complex models verified the effectiveness and the reliability of the algorithm proposed in this article.

Swelling behavior of sodium lignosulfonate grafted polyacrylic acid highly absorbent hydrogels with two-phase structure

There exist two theories on the swelling behavior of cross-linked polymer networks treated by statistical thermodynamic and scalar methods, respectively. These two theories predict inconsistent network chain length dependence of the swelling ratio. The swelling of biopolymer gels is analysed with scaling laws from polymer physics, as an alternative for the classical Flory-Rehner theory. In this paper, the swelling data of sodium lignosulfonate grafted polyacrylic acid cross-linked networks in good solvents are reanalyzed, and it is pointed out that these networks are a typical model network conforming to the two-phase structural picture. For the swelling behavior of gels in the semi-dilute regime we derive the scaling theory based swelling equations, which make them compact and universal character.

A variable diagonal-matrix-step-size APA robust to impulsive noises

This study introduces a variable diagonal-matrix-step-size affine projection algorithm (APA), which shows robustness against to impulsive noises. Unlike the normal scalar step-size method, the independent step size for each input vector is used as the entry of the diagonal matrix, and the optimal step size at each time step is ascertained by conducting mean-square-deviation (MSD) analysis. In addition, a recursive equation of weight update has been derived without approximating posteriori error as priori error. Using the Lagrange multiplier method, we formulate a scalar step size affine projection algorithm that shows resilience to impulsive noises. This algorithm emerges as a solution to a constrained optimization problem. To further enhance convergence performance, a diagonal-matrix-step size is introduced and its MSD is analyzed. The step size at each time step is optimized by interpreting the MSD mathematically, resulting in the variable diagonal-matrix-step size APA (VDMSS-APA). Various simulations exhibit low steady-state error and fast convergence rate of the proposed algorithm.

Decomposition with adaptive composite norm for evolutionary multi-objective combinatorial optimization

The multi-objective evolutionary algorithm based on decomposition (MOEA/D) decomposes a multi-objective problem into a series of single-objective subproblems for collaborative optimization. The weighted sum (WS) method and the Tchebycheff (TCH) method are the two most popular scalarization methods. They have pros and cons in solving multi-objective combinatorial optimization problems (MOCOPs) the WS method allows MOEA/D to converge faster than the TCH method; the WS-based MOEA/D cannot obtain unsupported non-dominated vectors, while the TCH-based one can overcome this shortcoming. This inspired us to use the WS method to drive the population towards the Pareto front and then switch to the TCH method to maintain a more diverse population. To better balance convergence and diversity, we propose a new scalarization strategy called adaptive composite norm (ACN). The ACN strategy can combine the WS and the TCH with dynamic weighting. The experiments consider 16 instances including 4 MOCOPs and run on the PlatEMO. Results reveal that MOEA/D-ACN can rank first and significantly outperform the other evolutionary multi-objective combinatorial optimization algorithms on almost all instances.

On characteristic behavior and flattened chromatic dispersion properties of bent photonic crystal fibers

Abstract In this paper by using modified scalar effective index method, first effective refractive index of straight and bent photonic crystal fibers are determined and then propagation parameters, such as chromatic dispersions for different structural designs of PCF, are obtained. By changing the values of affecting parameters in the bent PCF, such as different bent radius, distance between air holes Λ $\Lambda $ and air-filling factor d / Λ , $d/\Lambda ,$ the chromatic dispersion is determined in terms of propagating wavelengths. The obtained results of bent PCF are compared with the results of straight PCF. The results of the present paper might be useful in designing optical devices and sensing systems.

A generalized scalar auxiliary variable method for the time-dependent Ginzburg-Landau equations

A generalized scalar auxiliary variable method for the time-dependent Ginzburg-Landau equations

An improved pure quasi-P-wave equation for complex anisotropic media

Abstract An accurate pure qP-wave equation in transverse isotropic (TI) media and its efficient and stable implementation are valuable for seismic imaging and inversion. Owing to the complexity of the qP-wave phase velocity expression in anisotropic media, it is difficult to construct such a pure qP-wave equation. In this paper, we combine the Taylor expansion and scalar operator methods to formulate an efficient and stable pure qP-wave equation in TI media. First, the Taylor expansion method is used to convert the square-root term into a fractional term in the qP-wave phase velocity expression. We further improve the approximation accuracy of the resulting equation by a correction technique. Then, the scalar operator is applied to scalarize the equivalent form of the fractional term in the approximated dispersion equation, deriving a simple and easy-to-implement pure qP-wave equation. We use the optical flow method to compute the direction of wave propagation, which improves the calculation accuracy of the scalar operators. Numerical experiments with representative models demonstrate that the new method has higher accuracy and better adaptability to models with strong anisotropy, complex structure, and rapid variation of the tilt angle than previous methods.

Design And Simulation Of 10 kW BLDC Motor Speed Control For Electric Vehicles Using FOC Based On Fuzzy Logic Control

The use of electric vehicles in the current era has begun to spread evenly. Apart from the issue of air pollution produced by ICE vehicles, the ease and practicality of using electric vehicles is the reason why the public is starting to become interested in electric vehicles. Electric vehicle manufacturers are currently choosing BLDC motors for their production vehicles because they are considered suitable for applications that require high power and torque output. However, BLDC motors require more complicated control techniques than other DC motors. The commonly used BLDC motor speed control methods are trapezoidal scalar control and field oriented control. FOC is a type of BLDC motor control with a vector control method which has advantages in terms of efficiency compared to scalar control methods. Many studies on implementing FOC as speed control for BLDC motors, but the research that has been carried out still uses PI control as a basis, where it is known that PI control has shortcomings in the form of complexity in its design. Fuzzy Logic Control is known to be easy to design and reliable in control, so this paper will show the performance of Fuzzy-PI based FOC control as speed control for 10kW BLDC motor in simulation using Simulink program. The simulation results of proposed Fuzzy-PI based FOC method have better response than PI based FOC in terms of starting response with 6.43 times faster rise time, 2.45 times faster settling time, 96.31% lower overshoot value and reliability in overcoming disturbances up to 78.05% lower overshoot value and 2.33 times faster recovery time.

A linear, second-order accurate, positivity-preserving and unconditionally energy stable scheme for the Navier–Stokes–Poisson–Nernst–Planck system

Electrokinetic phenomena involving the transport of ions in fluids generally appears in biological system, hydrodynamics and geodynamics. The underlining mathematical models involve the nonlinear coupling between the fluid motion and ion transportation. Performing efficient, accurate and structure preserving computation for these electrohydrodynamic models is challenging due to their multiphysics and complex nature. The Navier–Stokes–Poisson–Nernst–Planck (NSPNP) system is a widely used electrokinetic model in the existing literature. In this paper, a linear, second-order accurate, positivity-preserving and unconditionally energy stable scheme is developed for the NSPNP system. First, a square root transformation is employed to ensure the positivity of ion concentrations. Next, a specific ordinary differential equation is introduced to deal with the nonlinear coupling terms satisfying the “zero-energy-contribution” feature, which is combined with the scalar auxiliary variable method for nonlinear potentials to achieve a decoupled energy stable scheme. Therefore, only several linearly independent equations need to be solved at each time step. The staggered grid finite difference method is used for the spatial discretizations, and the unconditional energy stability of the fully discrete scheme is established. Finally, the unique solvability of the scheme is proved. Numerical experiments are carried out to demonstrate the accuracy and performance of the proposed scheme, and the effect of electric Coulomb force on the flow and motion of ions are also illustrated.

Combining neutral scalar and isothermal Shan-Chen lattice Boltzmann method to simulate droplet placement on a wall in isothermal and non-isothermal states

BackgroundIn the current article, two-phase thermal fluxes are created by combining the thermal model of the neutral scalar model with the two-phase Shan-Chen model of the lattice Boltzmann method (LBM). MethodsThe different intermolecular powers for the isothermal Shan-Chen model show how a droplet would be placed on a wall. By raising the droplet intermolecular power parameter, the surface area increases and becomes wet. Next, the isothermal Shan-Chen method and the neutral scalar method are combined to investigate multi-phase thermal problems. The droplet placement on the hot wall is therefore done at relatively high Rayleigh numbers. By raising the Rayleigh number, the isothermal lines within the droplet's interior gradually become less ascending and less descending until they eventually achieve a uniform state when it is placed against a hot wall. Additionally, the channel's Rayleigh-Bénard convective heat transfer is enhanced by increasing the Rayleigh number. Significant findingsNatural convection in the enclosures can be used in solar collectors. As the Rayleigh number increases, the average Nusselt number (Nuavg) rises as would be expected. The results demonstrate that LBM is a practical method for simulating multi-phase thermal flows.

Psychometric Properties of the Tendency to Avoid Physical Activity and Sport Scale Among Hong Kong University Students

ABSTRACT The present study aimed to validate the Chinese version of the Tendency to Avoid Physical Activity and Sport Scale (TAPAS) among university students living in Hong Kong to assess weight and body image concerns. A convenience sample of 787 students (63.5% females; 24.5% overweight) were recruited online. The factor structure of the scale was examined using confirmatory factor analysis (CFA). Multigroup CFA was used to assess measurement invariance across gender and weight categories. The unidimensional structure of the scale was confirmed (χ2 = 78.046, CFI = 0.996). Factor loading ranged from 0.536 to 0.902, and internal consistency was good (α = .93, ω = .95). The scale was measurement invariant across gender and weight status using both metric and scalar invariance methods (−0.004<ΔCFI<-0.002). The scale can help to identify barriers of weight concerns regarding physical activity engagement which would help in the development of preventive interventions.

A Dual Scalar Magnetic Target Localization Method Using Anderson Basis Functions and Cuckoo-Search-Based Spiral Update

A Dual Scalar Magnetic Target Localization Method Using Anderson Basis Functions and Cuckoo-Search-Based Spiral Update

Theoretical design of polyazole based ligands for the separation of Am(III)/Eu(III)

The extraction of radioactive minor actinides (An(III)) from lanthanides (Ln(III)) is an extremely important step in nuclear waste reprocessing. Designing ligands with high-performance actinide-selectivity remains an essential task. Recent works have reported that some polyazole based ligands exhibit good An(III)/Ln(III) separation performance. Herein, we first evaluated the effects of different polyazole side chains on the Am(III)/Eu(III) selectivity by exploring three pyridine-derived polyazole ligands L1, L2 and L3 with 1,2,4-triazole, 1,2,3-triazole, and pyrazole side chains, respectively, using scalar relativistic theoretical methods. The coordination structures, bonding properties and thermodynamic behaviors of AmL(NO3)3 and EuL(NO3)3 complexes were investigated, which clarifies that the side chains do affect the electronic structure of ligand and its selectivity for Am(III)/Eu(III) ions. Moreover, L1 with 1,2,4-triazole side chains exhibited the highest selectivity for Am(III) over Eu(III) while the lowest complexation ability for metal ions among the three pyridine-derived polyazole ligands. Subsequently, we designed a new ligand L4 containing 1,2,4-triazole side chains and a preorganized phenanthroline backbone. Theoretically, such a new ligand was verified to show stronger complexation ability and higher selectivity for Am(III)/Eu(III) ions than L1. This work clarifies the complexation nature of polyazole based ligands with Am(III)/Eu(III) ions and provides design strategies for highly efficient polyazole based ligands for An(III)/Ln(III) separation.

Vector Field-Based Volume Peeling for Multi-Axis Machining

Abstract This paper presents an easy-to-control volume peeling method for multi-axis machining based on the computation taken on vector fields. The current scalar field-based methods are not flexible and the vector field-based methods do not guarantee the satisfaction of the constraints in the final results. We first conduct an optimization formulation to compute an initial vector field that is well aligned with those anchor vectors specified by users according to different manufacturing requirements. The vector field is further optimized to be an irrotational field so that it can be completely realized by a scalar field’s gradients. Iso-surfaces of the scalar field will be employed as the layers of working surfaces for multi-axis volume peeling in the rough machining. Algorithms are also developed to remove and process singularities of the fields. Our method has been tested on a variety of models and verified by physical experimental machining.

Development of the Phaseless Calibration Algorithm for a Digital Antenna Array

In this paper, we will discuss a calibration algorithm for a digital antenna array that diagnoses its real performance. It can be applied at such stages of the antenna system life cycle as design, tuning, and especially maintenance. A calibration implementation using a scalar method for a multi-beam digital antenna array is proposed and investigated. On-the-fly calibration ensures a continuous improvement in beam pointing accuracy by reducing internal errors in the receiving (transmitting) channels. The purpose of the study is to experimentally examine the capabilities of digital beamforming to increase the angle-of-arrival estimation accuracy. A simulation model of the receiving antenna was created in an anechoic chamber with a planar antenna positioner. The possibility of precise estimation of the direction of arrival using the digital beamforming with electronic scanning was demonstrated. The proposed simulation model made it possible to observe the convergence of the antenna array calibration process using the proposed method for various errors in the signal paths, as well as different signal-to-noise ratios. It has been proven that even under adverse conditions early in the calibration algorithm, the phase error detection converges with high accuracy, and its value decreases uniformly even to the fractions of an angular degree.

Optimality Conditions in Uncertain Multi-Objective Optimization Problems with a Variable Domination Structure

In this paper, we first establish some new properties of a kind of nonlinear scalarization function. Second, based on set approaches, we introduce a class of new definitions of robustness for an uncertain multi-objective optimization problem with a variable domination structure. Finally, by applying the scalarization method, we obtain the necessary and sufficient optimality conditions of the robustness for the uncertain multi-objective optimization problem with a variable domination structure in a more general setting. Some of the obtained results extend and imply the corresponding ones in recent literature.

A SMART methodology for assessment of hexanal in potato crisps using electronic nose technology: sensor screening by scalar machine learning classifier method.

The online version contains supplementary material available at 10.1007/s13197-023-05831-y.

Variable-step numerical schemes and energy dissipation laws for time fractional Cahn–Hilliard model

Two temporal second-order energy stable schemes with variable time step sizes are constructed for the time fractional Cahn–Hilliard model. Nonuniform L1+ formula is utilized for the discretization of the fractional derivative, while the nonlinear term is handled by the fully-implicit scheme and the scalar auxiliary variable method, respectively. By means of the recently proposed discrete gradient structure of the temporal discretization operator, the discrete energy dissipation laws are developed via a unified framework, which are stronger than the energy boundedness results reported in the previous literature. Moreover, the discrete energy decay nature coincides with the classical analogies as the fractional order tends to one. The optimal convergence rate is verified numerically, furthermore, the coarsening dynamics simulation demonstrates the efficiency of the variable-step schemes combined with the adaptive time strategy.