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INFLUENCE OF THE DISCRETIZATION STEP ON THE POSITIVITY OF CONFORMABLE FRACTIONAL LINEAR SYSTEMS

UPB Scientific Bulletin, Series A: applied mathematics and Physics 2023年第1期85卷 77-86页

作者： Benuettou, Kamel Ghezzar, Mohammed Amine Bougada, Djillali Abdelhamid Ibn Badis University Mostaganem ACSY Team-Laboratory of Pure and Applied Math-ematics Department of Mathematics and Computer Science Faculty SEI BP 227/118 Mostaganem27000 Algeria National Higher School of Mathematics ACSY Team-Laboratory of Pure and Applied Mathematics Algeria

The effectiveness of this work lies in the influence of the discretization step on the positivity of the one-dimensional conformable fractional linear systems. A piecewise constant approximation method which converts a continuous fractional order derivative into a discrete time equation is presented as an alternative approach. It aims at investigating whether, how and when this step affects the positive continuous times models. To accomplish this research, a new test was developed and implemented in which the positivity conditions of the considered system was examined both before and after being exposed to the sampling step. i.e., under which conditions the one-dimensional discrete-time linear system obtained by discretization from the one-dimensional continuous time linear systems will be also positive if the one-dimensional continuous time linear system is positive. The new method presented is suggested to test the influence of the discretization step on the positivity of this class of systems. Finally, we discuss some numerical examples to illustrate the validity of the provided results. © 2023, Politechnica University of Bucharest. All rights reserved.

关键词： Linear systems

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Control of a Wind Turbine Emulator Based on Variable Pitch Angle with a Self-Excited Induction Generator 4

Control of a Wind Turbine Emulator Based on Variable Pitch A...

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4th International Conference on Innovative Research in applied science, Engineering and Technology, IRASET 2024

作者： Boutahiri, Chaymaâ Nouaiti, Ayoub Mesbahi, Abdelouahed Hsaini, Abdallah Marhraoui Bouazi, Aziz Moulay Ismail University Ievia Team Est Laboratory Of Computer Science Applied Math And Electrical Engineering Meknès Morocco Systems Hassan Ii University Ensem Laboratory Of Energy & Electrical Casablanca Morocco

ISBN: (纸本)9798350309508

This article highlights the control of an electromechanical wind emulator designed to mimic the behavior of a wind turbine. The emulator employs a self-excited induction generator, which is driven by a DC motor. A DC-DC Buck converter adjusts the rotation speed, adapting to changes in the wind profile. A PI controller is employed to oversee and fine-tune the output current from the converter, ensuring alignment with the characteristics of the wind turbine model in use. The control strategy is crafted to oversee the wind turbine power based on the wind speed. This is achieved by adjusting the pitch angle value and tip speed, aiming to prevent wind turbine from stalling. The efficacy of the implemented control strategy is demonstrated in the Matlab-Simulink environment, where the proposed system is evaluated. The results show accurate tracking and no overshoot. © 2024 IEEE.

关键词： DC motors

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RAISE:A Resilient Anonymous Information Sharing Environment

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computer Modeling in Engineering & sciences 2023年第12期137卷 2743-2759页

作者： Ning Hu Ling Liu Xin Liu Kaijun Wu Yue Zhao Cyberspace Institute of Advanced Technology Guangzhou UniversityGuangzhou510006China Science and Technology on Communication Security Laboratory The 30th Research Institute of China Electronics Technology Group CorporationChengdu610041China College of Computer Engineering and Applied Math Changsha UniversityChangsha410022China

With the widespread application of cloud computing and network virtualization technologies,more and more enterprise applications are directly deployed in the ***,the traditional TCP/IP network transmission model does not fully consider the information security issues caused by the uncontrollable internet *** security communication solutions represented by encrypted virtual private networks(VPN)are facing multiple security *** fact,during the communication process,the user application needs to protect not only the content of the communication but also the behavior of the communication,such as the communication relationship,the communication protocol,and so *** by blockchain and software-defined networking technology,this paper proposes a resilient anonymous information sharing environment,*** RAISE system consists of user agents,a core switching network and a control cluster based on a consortium *** agents are responsible for segmenting,encrypting,and encapsulating user *** core switching network forwards user traffic according to the rules issued by the controller,and the controller dynamically calculates the forwarding rules according to the security *** from onion routing technology,RAISE adopts the controller to replace the onion routing model,which effectively overcomes the uncontrollability of *** dispersed computing model is introduced to replace the TCP/IP pipeline transmission models,which overcomes the problems of anti-tracking and traffic hijacking that cannot be solved by *** propose a blockchain control plane framework,design the desired consensus algorithmand deploy a RAISE systemconsisting of 150 nodes in an internet *** experimental results show that the use of blockchain technology can effectively improve the reliability and security of the control *** maintaining high-performance network transmission,it further provides network communicatio

关键词： Software-defined anonymous communication network blockchain network communication security

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Adjoint-Free 4D-Var Methods Via Line Search Optimization For Non-Linear Data Assimilation

arXiv

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arXiv 2023年

作者： Nino-Ruiz, Elias D. Diaz-Rodriguez, Jairo Applied Math and Computer Science Laboratory Department of Computer Science Universidad del Norte Colombia Department of Mathematics and Statistics York University Canada

This paper proposes two practical implementations of Four-Dimensional Variational (4D-Var) Ensemble Kalman Filter (4D-EnKF) methods for non-linear data assimilation. Our formulations' main idea is to avoid the intrinsic need for adjoint models in the context of 4D-Var optimization and, even more, to handle non-linear observation operators during the assimilation of observations. The proposed methods work as follows: snapshots of an ensemble of model realizations are taken at observation times, these snapshots are employed to build control spaces onto which analysis increments can be estimated. Via the linearization of observation operators at observation times, a line-search based optimization method is proposed to estimate optimal analysis increments. The convergence of this method is theoretically proven as long as the dimension of control-spaces equals model one. In the first formulation, control spaces are given by full-rank square root approximations of background error covariance matrices via the Bickel and Levina precision matrix estimator. In this context, we propose an iterative Woodbury matrix formula to perform the optimization steps efficiently. The last formulation can be considered as an extension of the Maximum Likelihood Ensemble Filter to the 4D-Var context. This employs pseudo-square root approximations of prior error covariance matrices to build control spaces. Experimental tests are performed by using the Lorenz 96 model. The results reveal that, in terms of Root-Mean-Square-Error values, both methods can obtain reasonable estimates of posterior error modes in the 4D-Var optimization problem. Moreover, the accuracies of the proposed filter implementations can be improved as the ensemble sizes are increased. © 2023, CC BY.

关键词： Optimization

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Performance Validation of a Three-Phase NPC Three-Level Inverter using a Novel Sinusoidal PWM technique for Induction Motor Scalar Control

Performance Validation of a Three-Phase NPC Three-Level Inve...

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Innovative Research in applied science, Engineering and Technology (IRASET),Conference on

作者： Badr N’Hili Souhail Barakat Karima Et-Torabi Abdelouahed Mesbahi Ayoub Nouaiti Mohamed Khafallah Departement Of Electrical Engineering LESE Laboratory ENSEM Hassan II University of Casablanca Morocco Laboratory of Computer Science Applied Math and Electrical Engineering EST Moulay Ismail University of Meknes Morocco

ISBN: (数字)9798331532970

ISBN: (纸本)9798331532987

Multilevel inverters have become essential tools in the field of electric energy conversion for both industrial environments and transportation. The performance provided by these converters, particularly in terms of efficiency and the quality of generated electrical signals, has secured them a prominent place in traction applications using asynchronous motors. This document aims to study the performance of an asynchronous motor controlled through a three-phase NPC three-level inverter using a novel modulation technique compared to a two-level inverter. Simulation results are validated using MATLAB/Simulink, while experimental results are obtained using a DSP card for control signal

关键词： Space vector pulse width modulation Total harmonic distortion Induction motors Simulation Transportation Switches Control systems Multilevel inverters Spectral analysis Periodic structures

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Detecting lithium plating dynamics in a solid-state battery with operando X-ray computed tomography using machine learning

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npj Computational Materials 2023年第1期9卷 1402-1410页

作者： Ying Huang David Perlmutter Andrea Fei-Huei Su Jerome Quenum Pavel Shevchenko Dilworth Y.Parkinson Iryna V.Zenyuk Daniela Ushizima Department of Materials Science&Engineering University of California IrvineIrvineCaliforniaUSA National Fuel Cell Research Center University of California IrvineIrvineCaliforniaUSA Applied Math and Computational Research Division Lawrence Berkeley National LaboratoryBerkeleyCaliforniaUSA Department of Chemical&Biomolecular Engineering University of California IrvineIrvineCaliforniaUSA Department of Electrical Engineering and Computer Sciences College of EngineeringUniversity of California BerkeleyBerkeleyCaliforniaUSA Advanced Photon Source Argonne National Laboratory9700 South Cass AvenueLemontIllinoisUSA Advanced Light Source Lawrence Berkeley National LaboratoryBerkeleyCaliforniaUSA Berkeley Institute for Data Science University of California BerkeleyBerkeleyCaliforniaUSA

Operando X-ray micro-computed tomography(µCT)provides an opportunity to observe the evolution of Li structures inside pouch *** is an essential step to quantitatively analyzingµCT datasets but is challenging to achieve on operando Li-metal battery datasets due to the low X-ray attenuation of the Li metal and the sheer size of the ***,we report a computational approach,batteryNET,to train an Iterative Residual U-Net-based network to detect Li *** resulting semantic segmentation shows singular Li-related component changes,addressing diverse morphologies in the *** addition,visualizations of the dead Li are provided,including calculations about the volume and effective thickness of electrodes,deposited Li,and redeposited *** also report discoveries about the spatial relationships between these *** approach focuses on a method for analyzing battery performance,which brings insight that significantly benefits future Li-metal battery design and a semantic segmentation transferrable to other datasets.

关键词： battery lithium state

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Control of a Wind Turbine Emulator Based on Variable Pitch Angle with a Self-Excited Induction Generator

Control of a Wind Turbine Emulator Based on Variable Pitch A...

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Innovative Research in applied science, Engineering and Technology (IRASET),Conference on

作者： Chaymaâ Boutahiri Ayoub Nouaiti Abdelouahed Mesbahi Abdallah Marhraoui Hsaini Aziz Bouazi Laboratory of Computer Science Applied Math and Electrical Engineering Moulay Ismail University IEVIA Team EST Meknès Morocco Laboratory of Energy & Electrical Systems Hassan II University ENSEM Casablanca Morocco

ISBN: (数字)9798350309508

ISBN: (纸本)9798350309515

关键词： Adaptation models Buck converters PI control Induction generators Wind speed DC motors mathematical models

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TLD-WF: Surfing Freely Under Website Fingerprinting Attacks 7

TLD-WF: Surfing Freely Under Website Fingerprinting Attacks

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7th IEEE International Conference on Data science in Cyberspace, DSC 2022

作者： Liu, Ling Liu, Xin Zhao, Yue Hu, Ning Cyberspace Institute of Advanced Technology GuangZhou University Guangzhou510006 China ChangSha University College of Computer Engineering and Applied Math Changsha410022 China Science and Technology on Communication Security Laboratory Chengdu610041 China Peng Cheng Laboratory Shenzhen518000 China

ISBN: (数字)9781665474801

ISBN: (纸本)9781665474801

Anonymous networks hide communication content and communication relationships by encrypting the content and transmission path of traffic. But the website fingerprinting attack can determine the websites a user visits by analyzing the user's traffic patterns and website fingerprints without decrypting the traffic. To defend against website fingerprinting attacks, most of the existing methods reduce the accuracy of analysis by increasing the access delay and background traffic. Unfortunately, such methods not only degrade the user experience, but also affect the performance of anonymity networks. By adopting the Tor pluggable transmission technology, this paper proposes a new targeted, lightweight defense to against website fingerprinting attack (TLD-WF). TLD-WF uses the TLD-flow module to obtain the analyzed flow information with an accuracy rate of over 90%, and conducts targeted dynamic scrambling. TLD-WF not only effectively guarantees the anonymity and security of Tor users, but also has the advantages of zero latency overhead and low bandwidth overhead. The experimental results show that TLD-flow can reduce the analysis accuracy of the CNN classifier from 93.2% to around 8.3% under normal conditions. With guaranteed zero latency and 45% bandwidth overhead, the analytical accuracy of the CNN classifier will be reduced by about 50%. © 2022 IEEE.

关键词： Websites

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Semi-Implicit Lagrangian Voronoi Approximation for Compressible Viscous Fluid Flows

arXiv

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arXiv 2024年

作者： Kincl, Ondřej Peshkov, Ilya Boscheri, Walter Laboratory of Applied Mathematics DICAM University of Trento Trento38123 Italy Laboratoire de Mathématiques UMR 5127 CNRS Université Savoie Mont Blanc Le Bourget du Lac73376 France Department of Mathematics and Computer Science University of Ferrara Ferrara44121 Italy

This paper contributes to the recent investigations of Lagrangian methods based on Voronoi meshes. The aim is to design a new conservative numerical scheme that can simulate complex flows and multi-phase problems with more accuracy than SPH (Smoothed Particle Hydrodynamics) methods but, unlike diffuse interface models on fixed grid topology, does not suffer from the deteriorating quality of the computational grid. The numerical solution is stored at particles, which move with the fluid velocity and also play the role of the generators of the computational mesh, that is efficiently re-constructed at each time step. The main novelty stems from combining a Lagrangian Voronoi scheme with a semi-implicit integrator for compressible flows. This allows to model low-Mach number flows without the extremely stringent stability constraint on the time step and with the correct scaling of numerical viscosity. The implicit linear system for the unknown pressure is obtained by splitting the reversible from the irreversible (viscous) part of the dynamics, and then using entropy conservation of the reversible sub-system to derive an auxiliary elliptic equation. The method, called SILVA (Semi-Implicit Lagrangian Voronoi Approximation), is validated in a variety of test cases that feature diverse Mach numbers, shocks and multi-phase flows. Copyright © 2024, The Authors. All rights reserved.

关键词： Topology

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Semi-implicit Lagrangian Voronoi Approximation for the incompressible Navier-Stokes equations

arXiv

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arXiv 2024年

作者： Kincl, Ondřej Peshkov, Ilya Boscheri, Walter Laboratory of Applied Mathematics DICAM University of Trento via Mesiano 77 Trento38123 Italy Laboratoire de Mathématiques UMR 5127 CNRS Université Savoie Mont Blanc Le Bourget du Lac73376 France Department of Mathematics and Computer Science University of Ferrara Ferrara Italy

We introduce Semi-Implicit Lagrangian Voronoi Approximation (SILVA), a novel numerical method for the solution of the incompressible Euler and Navier-Stokes equations, which combines the efficiency of semi-implicit time marching schemes with the robustness of time-dependent Voronoi tessellations. In SILVA, the numerical solution is stored at particles, which move with the fluid velocity and also play the role of the generators of the computational mesh. The Voronoi mesh is rapidly regenerated at each time step, allowing large deformations with topology changes. As opposed to the reconnection-based Arbitrary-Lagrangian-Eulerian schemes, we need no remapping stage. A semi-implicit scheme is devised in the context of moving Voronoi meshes to project the velocity field onto a divergence-free manifold. We validate SILVA by illustrative benchmarks, including viscous, inviscid, and multi-phase flows. Compared to its closest competitor, the Incompressible Smoothed Particle Hydrodynamics (ISPH) method, SILVA offers a sparser stiffness matrix and facilitates the implementation of no-slip and free-slip boundary conditions. Copyright © 2024, The Authors. All rights reserved.

关键词： Stiffness matrix

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