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10th Convention of the European Acoustics Association, EAA 2023

作者： Feriani, Sophia Julia Engsig-Karup, Allan P. Pind, Finnur Cosnefroy, Matthias Jeong, Cheol-Ho Acoustic Technology Department of Electrical and Photonics Engineering Technical University of Denmark Denmark Scientific Computing Department of Applied Mathematics and Computer Science Technical University of Denmark Denmark Treble Technologies Hafnartorg Kalkofnsvegur 2 Reykjavík101 Iceland

ISBN: (纸本)9788888942674

In environmental acoustics, sound propagates in open air and can be mathematically modelled in terms of a semi-infinite domain. The calculations for accurate numerical solutions for outdoor acoustics are computationally heavy when the chosen computation domain is large enough to fulfil the Sommerfeld radiation condition. To lower the computational cost, the domain must therefore be truncated to not significantly impact the numerical solution inside the domain and allow outgoing acoustic waves to leave the domain undisturbed. Various radiation conditions (sometimes considering the wind) have been developed to achieve this goal such as the Perfectly Matched Layer method. The aim of this study is to compare the accuracy of different non-reflecting boundaries using the high-order nodal discontinuous Galerkin finite element method (DG-FEM) for the case of an acoustic pulse propagating in a static and moving medium in an unstructured mesh. For each boundary treatment, the tunable parameters of the methods are defined to balance accuracy and computational cost. © 2023 S.J. Feriani et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 3.0 Unported License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

关键词： Galerkin methods

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Blind Equalization using a Variational Autoencoder with Second Order Volterra Channel Model

arXiv

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arXiv 2024年

作者： Nielsen, Søren Føns Zibar, Darko Schmidt, Mikkel N. The Department of Applied Mathematics and Computer Science Technical University of Denmark Denmark The Department of Electrical and Photonics Engineering Technical University of Denmark Denmark

Existing communication hardware is being exerted to its limits to accommodate for the ever increasing internet usage globally. This leads to non-linear distortion in the communication link that requires non-linear equalization techniques to operate the link at a reasonable bit error rate. This paper addresses the challenge of blind non-linear equalization using a variational autoencoder (VAE) with a second-order Volterra channel model. The VAE framework’s costfunction, the evidence lower bound (ELBO), is derived for real-valued constellations and can be evaluated analytically without resorting to sampling techniques. We demonstrate the effectiveness of our approach through simulations on a synthetic Wiener-Hammerstein channel and a simulated intensity modulated direct detection (IM/DD) optical link. The results show significant improvements in equalization performance, compared to a VAE with linear channel assumptions, highlighting the importance of appropriate channel modeling in unsupervised VAE equalizer frameworks. © 2024, CC BY.

关键词： Optical links

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A POLYNOMIAL APPROXIMATION SCHEME FOR NONLINEAR MODEL REDUCTION BY MOMENT MATCHING

arXiv

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arXiv 2024年

作者： Doebeli, Carlos Astolfi, Alessandro Kalise, Dante Moreschini, Alessio Scarciotti, Giordano Simard, Joel Department of Applied Mathematics Imperial College London United Kingdom Department of Electrical and Electronic Engineering Imperial College London United Kingdom

MSC Codes 49M15, 70Q05, 93A30We propose a procedure for the numerical approximation of invariance equations arising in the moment matching technique associated with reduced-order modeling of high-dimensional dynamical systems. The Galerkin residual method is employed to find an approximate solution to the invariance equation using a Newton iteration on the coefficients of a monomial basis expansion of the solution. These solutions to the invariance equations can then be used to construct reduced-order models. We assess the ability of the method to solve the invariance PDE system as well as to achieve moment matching and recover a system’s steady-state behaviour for linear and nonlinear signal generators with system dynamics up to n = 1000 dimensions. Copyright © 2024, The Authors. All rights reserved.

关键词： Galerkin methods

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Improving Image Captioning Using Deep Convolutional Neural Network 2

Improving Image Captioning Using Deep Convolutional Neural N...

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2nd International engineering Conference on electrical, Energy, and Artificial Intelligence, EICEEAI 2023

作者： Basiri, Fahimeh Mohammadi, Alireza Amer, Ayman Ranjbar Naserabadi, Mohammad Javad Moghimi, Mohammad Mahdi Tarbiat Modares University Applied Mathematics Department Tehran Iran Zarqa University Faculty of Engineering Zarqa Jordan College of Engineering University of Business and Technology Jeddah21448 Saudi Arabia Petroleum University of Technology Technical Inspection Department Abadan Iran Yazd Branch Islamic Azad University Department of Electrical Engineering Yazd Iran

ISBN: (纸本)9798350373363

Image captioning is a challenging task that requires a computer vision system to generate natural language descriptions for images. The aim is to build a model that can comprehend the visual content of an image and produce a coherent and accurate caption for it. This technology has various applications in domains such as assistive technology for visually impaired people, image search engines, image understanding in artificial intelligence systems, education, social media, and more. In recent years, recurrent neural networks (RNNs) with long-short-term memory (LSTM) units have been widely used for image captioning. However, RNNs have some limitations in capturing long-term dependencies and modeling complex language structures. In this paper, we propose a novel image captioning method that uses a convolutional neural network (CNN) to extract image features and a bidirectional encoder representation of transformers (BERT) to generate captions. BERT is an advanced language model that uses a transformer architecture to learn bidirectional context embeddings for words in a sentence. We train our hybrid model on a small-scale dataset of images and captions. We evaluate our model on several metrics and compare it with LSTM method. Our results show that our model achieves reliable performance and acceptable error rate (loss score). We also demonstrate that our model can generate more diverse and rich captions than RNN-based models. © 2023 IEEE.

关键词： Long short-term memory

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Analysis of the thermal and electrical parameters of the supply system of an HTS superconducting electromagnet 12

Analysis of the thermal and electrical parameters of the sup...

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12th International Conference and Exposition on electrical and Power engineering, EPE 2022

作者： Dumitru, George Morega, Alexandru Dobrin, Ion Enache, Dan Nedelcu, Adrian National Institute for Research and Development for Electrical Engineering ICPE-CA Applied Superconductivity Laboratory Bucharest Romania University Politehnica of Bucharest Faculty of Electrical Engineering Bucharest Romania 'Gh. Mihoc - C. Iacob' Institute of Statistical Mathematics and Applied Mathematics Romanian Academy Romania National Institute for Research and Development for Electrical Engineering ICPE-CA Department of Electromechanical Systems and Technologies Bucharest Romania

ISBN: (数字)9781665489942

ISBN: (纸本)9781665489942

The proper functioning of a high-temperature superconducting (HTS) electromagnet requests a DC of 300 A supply to obtain a magnetic flux density of 5 T. The current must be applied to the HTS electromagnet through the aid of mixed chain conductors, comprising two types: a copper one and the second, an HTS conductor connected to the magnet. The copper conductor connects the outer terminal on the cryostat to one end of the HTS conductor, having a temperature of 50 K. The second (HTS conductor) has one end at 50 K and the second at 4.2 K, the magnet's temperature. The cooling of the HTS magnet is performed by a Gifford-McMahon cryocooler with two cooling stages: 50 K and 4.2 K. The work aims to design the current conductors and evaluate the heating flux towards the magnet and temperature profile of the system to comply with the cooling power of the cryocooler. © 2022 IEEE.

关键词： Cooling

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On the design of multiplex control to reject disturbances in nonlinear network systems affected by heterogeneous delays

On the design of multiplex control to reject disturbances in...

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American Control Conference (ACC)

作者： Shihao Xie Giovanni Russo School of Electrical and Electronic Engineering University College Dublin Ireland Department of Information and Electrical Engineering and Applied Mathematics University of Salerno Italy

We consider the problem of designing control protocols for nonlinear network systems affected by heterogeneous, time-varying delays and disturbances. For these networks, the goal is to reject polynomial disturbances affecting the agents and to guarantee the fulfilment of some desired network behaviour. To satisfy these requirements, we propose an integral control design implemented via a multiplex architecture. We give sufficient conditions for the desired disturbance rejection and stability properties by leveraging tools from contraction theory. We illustrate the effectiveness of the results via a numerical example that involves the control of a multi-terminal high-voltage DC grid.

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Discrete fully probabilistic design: towards a control pipeline for the synthesis of policies from examples

Discrete fully probabilistic design: towards a control pipel...

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Mediterranean Conference on Control and Automation (MED)

作者： Enrico Ferrentino Pasquale Chiacchio Giovanni Russo Department of Computer and Electrical Engineering and Applied Mathematics (DIEM) University of Salerno Fisciano SA Italy

We present the principled design of a control pipeline for the synthesis of policies from examples data. The pipeline, based on a discretized design, expounds the algorithm introduced in [1] to synthesize policies from examples for constrained, stochastic and nonlinear systems. The pipeline: (i) does not need the constraints to be fulfilled in the possibly noisy example data; (ii) enables control synthesis even when the data are collected from an example system that is different from the one under control. The design is benchmarked on an example that involves controlling an inverted pendulum with actuation constraints. The data that are used to synthesize the policy are collected from a pendulum that: (i) is different from the one under control; (ii) does not satisfy the actuation constraints.

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CONVERGENCE OF DISCONTINUOUS GALERKIN METHODS FOR QUASICONVEX AND RELAXED VARIATIONAL PROBLEMS

arXiv

引用

arXiv 2025年

作者： Grekas, Georgios Koumatos, Konstantinos Makridakis, Charalambo Vikelis, Andreas Computer Electrical Mathematical Sciences and Engineering Division KAUST Saudi Arabia Department of Mathematics University of Sussex United Kingdom Institute of Applied & Computational Mathematics Foundation for Research & Technology-Hellas Greece Department of Mathematics and Applied Mathematics University of Crete Greece Faculty of Civil Engineering Czech Technical University of Prague Czech Republic

In this work, we establish that discontinuous Galerkin methods are capable of producing reliable approximations for a broad class of nonlinear variational problems. In particular, we demonstrate that these schemes provide essential flexibility by removing inter-element continuity while also guaranteeing convergent approximations in the quasiconvex case. Notably, quasiconvexity is the weakest form of convexity pertinent to elasticity. Furthermore, we show that in the non-convex case discrete minimisers converge to minimisers of the relaxed problem. In this case, the minimisation problem corresponds to the energy defined by the quasiconvex envelope of the original energy. Our approach covers all discontinuous Galerkin formulations known to converge for convex energies. This work addresses an open challenge in the vectorial calculus of variations: developing and rigorously justifying numerical schemes capable of reliably approximating nonlinear energy minimization problems with potentially singular solutions, which are frequently encountered in materials science. © 2025, CC BY.

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Research on the Performance of Porous-Si/Si Photoconverters by Optimizing the Anti-Reflective Coating Using PC1D Modeling 5

Research on the Performance of Porous-Si/Si Photoconverters ...

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5th IEEE KhPI Week on Advanced Technology, KhPIWeek 2024

作者： Dyadenchuk, Alena Halko, Serhii Halko, Kateryna Miroshnyk, Oleksandr Hussienat, Lina H. Moroz, Oleksandr Department of Higher Mathematics and Physics Dmytro Motornyi Tavria State Agrotechnological University Melitopol Ukraine Department of Electrical Engineering and Electromechanics Named after Prof. V.V. Ovharov Dmytro Motornyi Tavria State Agrotechnological University Melitopol Ukraine Jagiellonian University Cracow Poland Department of Electricity Supply and Energy Management State Biotechnological University Kharkiv Ukraine Department Electrical Power Engineering Al Balqa Applied University Al Salt Jordan

ISBN: (纸本)9798350384499

In the paper, a porous-Si/Si solar element with single- and double-layer anti-reflective coatings is simulated using PC1D simulation software. The reflection of eight monolayers (Si3N4, ZnO, ZnS, TiO2, SiO2, SiC, MgF2, Al2O3) and nine double-layered (SiO2/ZnS, MgF2/Si3N4, MgF2/SiO2 і SiO2/Al2O3, TiO2/SiO2, TiO2/Si3N4, TiO2/ZnO, SiO2/ZnS, MgF2/ZnS) anti-reflective coatings was studied. These are the most often used in the production of silicon solar elements. Optical propagation and absorption of photoconverters are considered using the transfer matrix method. The results showed that the best reflectance is observed for SiO2/ZnS, MgF2/Si3N4, MgF2/SiO2 і SiO2/Al2O3 double anti-reflective coatings, which were later used to model the photovoltaic parameters of porous-Si/Si solar cells. A decrease in the reflection of visible light indicates a better use of the incident solar radiation. The highest efficiency of 24.6% was achieved for devices on the base DLARC SiO2/ZnS. For DLARC MgF2/Si3N4, MgF2/SiO2 and SiO2/Al2O3 the efficiency was 24.1, 21.8 and 23.5%, respectively. In order to evaluate reflection losses due to texturing of the front surface, modeling of photoconverters with a pyramidal texture 3 μm deep with an angle of 0-89° was carried out. For the investigated DLARC/porous-Si/Si, the efficiency changed with an increase in the angle by 1.5-2.6%, taking the maximum value at angles of 85-87°. ©2024 IEEE.

关键词： Incident solar radiation

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Two-Stage Time-Optimal Planning of Robots Along Pre-Scribed Paths with Integral Optimization of Redundancy

Two-Stage Time-Optimal Planning of Robots Along Pre-Scribed ...

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International Conference on Control, Decision and Information Technologies (CoDIT)

作者： Federica Storiale Enrico Ferrentino Pasquale Chiacchio Department of Computer and Electrical Engineering and Applied Mathematics (DIEM) University of Salerno Fisciano SA Italy

The problem of time-optimal planning of redundant robots is commonly solved with a decoupled two-stage approach. Starting from a task space path, at the first stage, the kinematic redundancy is locally optimized according to some performance index, then, at the second stage, the time-optimal parametrization of the resulting joint space path is performed. The performance indices to consider, as well as the redundancy resolution technique to adopt, impact the overall trajectory duration. First- or second-order Jacobian-based local redundancy resolution does not always guarantee satisfactory results at the second stage, in terms of trajectory duration, due to the choice of the initial positions, tuning of algorithm parameters, difficult joint limits management, non-convexity of the optimization problem. In this paper, we propose a global (or integral) approach for redundancy resolution, based on discrete dynamic programming, which further reduces the trajectory tracking time. To cope with the discretization of the redundancy space, the proposed methodology includes a post-processing optimization stage, aimed at smoothing the resulting joint space trajectory, guaranteeing technical feasibility. The approach is validated, in simulation, on a three-degrees-of-freedom planar robot executing two-dimensional tasks.

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