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Modulation of a trapezoidal signal: improving signal quality and reducing costs in power inverters

IET POWER ELECTRONICS 2017年第5期10卷 568-576页

作者： Juan Sotorrio-Ruiz, Pedro Sanchez-Pacheco, Francisco J. Perez-Hidalgo, Francisco M. Heredia-Larrubia, Juan Ramon Univ Malaga Elect Technol Dept Escuela Ingn C Dr Ortiz Ramos S-N Malaga Spain Univ Malaga Elect Engn Dept Escuela Ingn C Dr Ortiz Ramos S-N Malaga Spain

Power inverters applied in industries have seen a growth in modulation techniques over recent years. The aim of modulation techniques is to improve the quality of the inverter output signal and to reduce inverter losses. To improve an output signal, the amplitude of the fundamental frequency should be increased and the harmonics should be reduced. If a modulation technique can achieve these two objectives, a much smaller output filter is required to reduce hardware cost and filter losses. In this study, a technique is proposed where the obtained modulated signal can be directly used without the need of filtering. The resulting frequency profile fulfils the EN50160 standard, which sets the limits for harmonic components to ensure the quality in public low-voltage and medium-voltage power supplies. In addition, the proposed scheme requires a low computational algorithm allowing the use of low-cost microprocessors or Digital Signal Processor (DSPs). The proposed algorithm is based on a simple vector seed, making it possible to obtain all the patterns of Pulse Width Modulation (PWM).

关键词： PWM invertors cost reduction power harmonic filters power supply quality digital signal processing chips trapezoidal signal modulation signal quality improvement cost reduction power inverters inverter loss reduction filter losses hardware cost reduction frequency profile EN50160 standard harmonic components public low-voltage power supply quality public medium-voltage power supply quality computational algorithm low-cost microprocessors DSP PWM patterns

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Process Plan for Multimaterial Heterogeneous Object in Additive Manufacturing

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3D PRINTING AND ADDITIVE MANUFACTURING 2014年第4期1卷 210-218页

作者： Khoda, Bashir N Dakota State Univ Ind & Mfg Engn Dept 1410 14th Ave North202F Fargo ND 58104 USA

Additive manufacturing (AM) is evolving toward multimaterial processes for improved functionality and performance. A recently developed AMF format provides the platforms for digitizing multimaterial/feature model suitable for AM processes. However, the current build strategies of monomaterial may not be appropriate for multimaterial objects presented in AMF format. The internal architecture of the part cannot be ignored in heterogeneous solids and functional porous objects. The material deposition path-plan in such multifeature objects can be interrupted by frequent directional changes and/or secondary material source activation. Dealing with these interruptions during fabrication requires more resources and may affect the part integrity, quality, and build time. This research aims to minimize such interruptions by focusing on build direction. A computational algorithm is proposed for the heterogeneous object that quantifies the build direction considering the feature characteristics and manufacturing attributes in order to bundle the slices based on the heterogeneity. The proposed methodology is illustrated by two heterogeneous models and generates more than 42% homogeneous slices generated for both examples. Higher heterogeneity is consolidated in strips that may require more resources during fabrication. Thus, differentiating and bundling the slice based on the resources requirement would certainly benefit the process plan for the multimaterial additive manufacturing technique.

关键词： Additive manufacturing computational algorithm

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Fast and accurate computation of interactions between linear fiber segments

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ENGINEERING COMPUTATIONS 2021年第7期38卷 3061-3076页

作者： Pal, Anirban West Texas A&M Univ Coll Engn Canyon TX 79016 USA

Purpose Fiber networks represent a vast class of materials, which can be modeled by representing its microstructure using one-dimensional fiber embedded in three-dimensional space. Investigating the statics, dynamics and thermodynamics of such structures from computational first principles requires the efficient estimation of cohesive-repulsive energies and forces between interacting fiber segments. This study offers a fast, efficient and effective computational methodology to estimate such interactions which can be coupled with Hamiltonian mechanics to simulate the behavior of fibrous systems. Design/methodology/approach This method preserves the uniformly continuous distribution of particles on the line segments and utilizes adaptive numerical integration of relevant distance-distribution functions to estimate the effective interaction energy and forces. Findings This method is found to be cheaper to compute and more accurate than the corresponding discrete scheme. This scheme is also versatile in the sense that any pair-wise interaction model can be used. Research limitations/implications The scheme depends on the availability of a suitable pair-interaction potential, such as a Lennard-Jones potential or Morse potential. Additionally, it can only be used for systems which are purely fibrous in nature. For example, fiber composites with a non-fibrous matrix are not addressed. Practical implications Paper, woven and hair can be represented as purely fibrous at some relevant length scales and are thus excellent candidate systems for this scheme. Originality/value This paper presents a novel method which allows rapid and accurate implementation of an otherwise computationally expensive process.

关键词： Distance-distribution function Interaction energy computational algorithm Fiber networks

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Exact solution of bending problem for continuous sandwich panels with profiled facings

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JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH 2014年 101卷 53-60页

作者： Gosowski, Bronislaw Gosowski, Maciej Wroclaw Univ Technol Inst Bldg Engn PL-50370 Wroclaw Poland PROKON PL-54142 Wroclaw Poland

The paper presents a closed-form solution, in the distributional form, of the bending problem for continuous sandwich panels in lightweight cladding that has been derived from the general solution of the system of differential equations for the problem of sandwich beams with thick facings. The analysis covers three-layer members with facings made from profiled metal sheets and a core having good insulating properties, for any number and spacing of elastic intermediate supports. Panels are subjected to bending under uniform transverse load and a load caused by temperature difference. The solution for the multi-span panels inflexibly (rigidly) pin-supported at their ends is derived from the general solution for members arbitrarily supported at their ends. A calculation algorithm for this type of panels is provided. Numerical examples are included to illustrate the influence of the intermediate supports on the effort of both the entire sandwich panel and its profiled facing. Finally, practical concluding remarks are given. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Lightweight cladding Sandwich panel (beam) Thick face Global static analysis computational algorithm Distribution calculus

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Soft-constrained stochastic Nash games for weakly coupled large-scale systems

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AUTOMATICA 2009年第5期45卷 1272-1279页

作者： Mukaidani, Hiroaki Hiroshima Univ Grad Sch Educ Higashihiroshima 7398524 Japan

In this paper, we discuss infinite-horizon soft-constrained stochastic Nash games involving state-dependent noise in weakly coupled large-scale systems. First, we formulate linear quadratic differential games in which robustness is attained against model uncertainty. It is noteworthy that this is the first time conditions for the existence of robust equilibria have been derived based on the solutions of sets of cross-coupled stochastic algebraic Riccati equations (CSAREs). After establishing an asymptotic structure with positive definiteness for CSAREs solutions, we derive a recursive algorithm by means of Newton's method so that it can be used to obtain solutions for CSAREs. As another important feature, we propose a high-order approximate Nash strategy based on iterative solutions. Finally, we provide a numerical example to verify the efficiency of the proposed algorithms. (C) 2009 Elsevier Ltd. All rights reserved.

关键词： Weakly coupled large-scale systems Soft-constrained stochastic Nash games computational algorithm

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A convexity preserving scheme for conservative advection transport

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JOURNAL OF computational PHYSICS 2004年第2期198卷 389-402页

作者： Xiao, F Peng, XD Tokyo Inst Technol Dept Energy Sci Midori Ku Yokohama Kanagawa 2268502 Japan JAMSTEC Earth Simulator Ctr Kanazawa Ku Yokohama Kanagawa 2360001 Japan

A simple and practical scheme for advection transport equation is presented. The scheme, namely piecewise rational method (PRM), is a variant of the existing piecewise parabolic method (PPM) of Colella and Woodward (1984). Instead of the parabolic function, a rational function is used for the reconstruction. Making use of the convexity preserving nature of the rational function enables us to obtain oscillation-less numerical solutions, but avoids the adjustments of the cell-interface values to enforce the monotonicity in PPM. The PRM is very simple and computationally efficient. Our numerical results show that PRM is competitive to the PPM in many aspects, such as numerical accuracy and shape-preserving property. (C) 2004 Elsevier Inc. All rights reserved.

关键词： advection transport computational algorithm rational interpolation convexity preserving numerical oscillation mass conservation

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Computing the conditional stationary distribution in Markov chains of level-dependent M/G/1-type

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STOCHASTIC MODELS 2018年第2期34卷 207-238页

作者： Kimura, Masatoshi Takine, Tetsuya Osaka Univ Grad Sch Engn Dept Informat & Commun Technol Suita Osaka 5650871 Japan

This paper considers the computation of the conditional stationary distribution in Markov chains of level-dependent M/G/1-type, given that the level is not greater than a predefined threshold. This problem has been studied recently and a computational algorithm is proposed under the assumption that matrices representing downward jumps are nonsingular. We first show that this assumption can be eliminated in a general setting of Markov chains of level-dependent G/G/1-type. Next we develop a computational algorithm for the conditional stationary distribution in Markov chains of level-dependent M/G/1-type, by modifying the above-mentioned algorithm slightly. In principle, our algorithm is applicable to any Markov chain of level-dependent M/G/1-type, if the Markov chain is irreducible and positive-recurrent. Furthermore, as an input to the algorithm, we can set an error bound for the computed conditional distribution, which is a notable feature of our algorithm. Some numerical examples are also provided.

关键词： computational algorithm conditional stationary distribution error bound level dependence Markov chains of M/G1-type

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Realizable algorithm for approximating Hilbert-Schmidt operators via Gabor multipliers

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JOURNAL OF computational AND APPLIED MATHEMATICS 2018年 337卷 119-124页

作者： Onchis, Darian M. Zappala, Simone Univ Vienna Fac Math Vienna Austria West Univ Timisoara Fac Math & Comp Sci Timisoara Romania

In this work, we consider new computational aspects to improve the approximation of Hilbert-Schmidt operators via generalized Gabor multipliers. One aspect is to consider the approximation of the symbol of an Hilbert-Schmidt operator as L-2 projection in the spline-type space associated to a Gabor multiplier. This gives the possibility to employ a selection procedure of the analysis and synthesis function, interpreted as time-frequency lag;hence, with the related algorithm it is possible to handle both underspread and overspread operators. In the numerical section, we exploit the case of approximating overspread operators having compact and smooth spreading function and discontinuous time-varying systems. For the latter, the approximation of discontinuities in the symbol is not directly achievable in the generalized Gabor multipliers setting. For this reason, another aspect is to further process the symbol through a Hough transform, to detect discontinuities and to smooth them using a new class of approximants. This procedure creates a bridge between features detection techniques and harmonic analysis methods, and in specific cases it almost doubles the accuracy of approximation. (C) 2018 The Authors. Published by Elsevier B.V.

关键词： Spline-type spaces computational algorithm Gabor multipliers Hough transform Hilbert-Schmidt operators approximation

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Application of the Fictitious Domain Method for Navier-Stokes Equations

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Computers, Materials & Continua 2022年第10期73卷 2035-2055页

作者： Almas Temirbekov Zhadra Zhaksylykova Yerzhan Malgazhdarov Syrym Kasenov Al-Farabi Kazakh National University AlmatyKazakhstan Abai Kazakh National Pedagogical University AlmatyKazakhstan Sarsen Amanzholov East Kazakhstan University Ust-KamenogorskKazakhstan

To apply the fictitious domain method and conduct numericalexperiments, a boundary value problem for an ordinary differential equation is considered. The results of numerical calculations for different valuesof the iterative parameter τ and the small parameter ε are presented. Astudy of the auxiliary problem of the fictitious domain method for NavierStokes equations with continuation into a fictitious subdomain by highercoefficients with a small parameter is carried out. A generalized solutionof the auxiliary problem of the fictitious domain method with continuationby higher coefficients with a small parameter is determined. After all theabove mathematical studies, a computational algorithm has been developedfor the numerical solution of the problem. Two methods were used to solvethe problem numerically. The first variant is the fictitious domain methodassociated with the modification of nonlinear terms in a fictitious *** model problem shows the effectiveness of using such a modification. Theproposed version of the method is used to solve two problems at once that arisewhile numerically solving systems of Navier-Stokes equations: the problem ofa curved boundary of an arbitrary domain and the problem of absence of aboundary condition for pressure in physical formulation of the internal flowproblem. The main advantage of this method is its universality in developmentof computer programs. The second method used calculation on a uniform gridinside the area. When numerically implementing the solution on a uniformgrid inside the domain, using this method it’s possible to accurately take intoaccount the boundaries of the curved domain and ensure the accuracy of thevalue of the function at the boundaries of the domain. Methodical calculationswere carried out, the results of numerical calculations were obtained. Whenconducting numerical experiments in both cases, quantitative and qualitativeindicators of numerical results coincide.

关键词： Fictitious domain method Navier-Stokes equations difference schemes approximation computational algorithm numerical experiment

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Receding Horizon Control With Numerical Solution for Nonlinear Parabolic Partial Differential Equations

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IEEE TRANSACTIONS ON AUTOMATIC CONTROL 2013年第3期58卷 725-730页

作者： Hashimoto, Tomoaki Yoshioka, Yusuke Ohtsuka, Toshiyuki Osaka Univ Dept Syst Innovat Toyonaka Osaka 5608531 Japan JFE Steel Corp Tokyo 1000011 Japan Osaka Univ Toyonaka Osaka 5608531 Japan

The optimal control of nonlinear partial differential equations (PDEs) is an open problem with applications that include fluid, thermal, biological, and chemical systems. Receding horizon control is a kind of optimal feedback control, and its performance index has amoving initial time and a moving terminal time. In this study, we develop a design method of receding horizon control for systems described by nonlinear parabolic PDEs. The objective of this study is to develop a novel algorithm for numerically solving the receding horizon control problem for nonlinear parabolic PDEs. The effectiveness of the proposed method is verified by numerical simulations.

关键词： computational algorithm distributed systems nonlinear systems optimal control

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