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SSRN 2024年

作者： Seo, Dong Hyun Kim, Hyung Rae Yun, Joo Ho Kim, Do Hyeon Heo, Se-Yeon Ma, Rujun Lee, Gil Ju Song, Young Min School of Electrical Engineering and Computer Science Gwangju Institute of Science and Technology Gwangju61005 Korea Republic of School of Materials Science and Engineering National Institute for Advanced Materials Smart Sensing Interdisciplinary Science Center Nankai University Tianjin300350 China Department of Electronics Engineering Pusan National University Busan46241 Korea Republic of AI Graduate School Gwangju Institute of Science and Technology Gwangju61005 Korea Republic of

Solid-state refrigeration, exploiting the electrocaloric (EC) effect, has sparked substantial interest due to its minimal energy consumption and zero-carbon emissions. However, one challenge to solid-state refrigeration technology resides in the limitation of cooling performance by the adiabatic temperature change (ΔT) inherent to caloric materials. To fully replace the traditional cooling technology, an augmentation of the innate heat dissipation capability beyond the intrinsic properties of the material is essential. In this study, we pioneer a method to transcend the native heat dissipation threshold of EC, by implementing a novel radiative heat sink/source-integrated electrocaloric (R-iEC) thermal regulation system. This system ingeniously leverages the outer cold space as a heat sink without energy. Moreover, a non-metallic thermally conductive radiative cooler (TCRC) is implemented with both a high thermal conductivity of 1.1 W/mK and exceptional spectral features (i.e., solar reflectivity ~96% and emissivity ~95% in atmospheric window region). The R-iEC system fortified with the TCRC demonstrates superior heat dissipation relative to conventional EC and radiative cooling, with an extra cooling heat flux of 87 W/m2. This improvement yields a temperature decrease of the heat source by 7.3 K relative to ambient temperature, showcasing the potential for a novel and zero-carbon emission cooling system. © 2024, The Authors. All rights reserved.

关键词： Heat flux

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Gaussian Process Port-Hamiltonian Systems: Bayesian Learning with Physics Prior

Gaussian Process Port-Hamiltonian Systems: Bayesian Learning...

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IEEE Conference on Decision and Control

作者： Thomas Beckers Jacob Seidman Paris Perdikaris George J. Pappas Department of Electrical and Systems Engineering University of Pennsylvania Philadelphia PA USA graduate program in Applied Mathematics and Computational Science University of Pennsylvania Philadelphia PA USA Department of Mechanical Engineering and Applied Mechanics University of Pennsylvania Philadelphia PA USA

ISBN: (数字)9781665467612

ISBN: (纸本)9781665467629

Data-driven approaches achieve remarkable results for the modeling of complex dynamics based on collected data. However, these models often neglect basic physical principles which determine the behavior of any real-world system. This omission is unfavorable in two ways: The models are not as data-efficient as they could be by incorporating physical prior knowledge, and the model itself might not be physically correct. We propose Gaussian Process Port-Hamiltonian systems (GPPHS) as a physics-informed Bayesian learning approach with uncertainty quantification. The Bayesian nature of GP-PHS uses collected data to form a distribution over all possible Hamiltonians instead of a single point estimate. Due to the underlying physics model, a GP-PHS generates passive systems with respect to designated inputs and outputs. Further, the proposed approach preserves the compositional nature of Port-Hamiltonian systems.

关键词： Uncertainty Gaussian processes Probabilistic logic Data models Bayes methods Behavioral sciences Kernel

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Nanometer-Scale Photodetectors for High Performance and Unique Functionality

Nanometer-Scale Photodetectors for High Performance and Uniq...

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International Conference on Emerging Wireless Communication Technologies and Information Security, EWCIS 2020

作者： Inokawa, Hiroshi Satoh, Hiroaki Banerjee, Amit Nagarajan, Anitharaj Manivannan, Revathi Singh, Alka Nishimura, Tomoki Isogai, Koki Research Institute of Electronics Shizuoka University Shizuoka Japan Department of Electrical and Computer Engineering National University of Singapore Singapore Singapore Graduate School of Science and Technology Shizuoka University Shizuoka Japan Graduate School of Integrated Science and Technology Shizuoka University Shizuoka Japan

ISBN: (纸本)9789813363922

As opposed to the case with MOSFETs widely used in the very-large-scale integrated circuit, miniaturization of the photodetectors to the nanometer scale does not always lead the performance improvement mainly due to the reduced thickness and area for the light absorption. However, it is still possible to circumvent the drawback by introducing the optical antenna and to improve the performance by miniaturization. Moreover, the nanometer-scale photodetectors exhibits unique functionalities such as incident angle detection and biosensing. In this report, some examples found in the photodiode with SP antenna, MOSFET single-photon detector, SET-based ultrahigh-frequency rectifier, and terahertz bolometer are introduced. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Photons

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Penrose Super-Radiance in a Synthetically Rotating Metasurface

Penrose Super-Radiance in a Synthetically Rotating Metasurfa...

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2022 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting, AP-S/URSI 2022

作者： Moussa, Hady Alù, Andrea City University of New York Photonics Initiative Advanced Science Research Center New York10031 United States City College of the City University of New York Department of Electrical Engineering New York10031 United States City University of New York Physics Program Graduate Center New YorkNY10016 United States

ISBN: (数字)9781665496582

ISBN: (纸本)9781665496582

Super-radiant amplification of scattering in a rotating medium was predicted by Sir Penrose as an exotic astrophysics phenomenon. Here we demonstrate its electromagnetic analogue using spatio-temporally modulated metasurfaces that experience a form of synthetic rotation. We consider excitations with signals carrying orbital angular momentum (OAM), highly beneficial for multiplexed wireless networks that demand high data rate capacity. The metasurface efficiently couples and can amplify selected OAM orders based on a phenomenon analogous to Penrose super-radiance. We build, analyze, and simulate a single circuit element, modulated in time through varactors, that efficiently manipulates three OAM orders and selectively amplifies them. We then show the possibility of observing angular Doppler shift and amplifying selected OAM signals using an array of these elements forming a metasurface. © 2022 IEEE.

关键词： Astrophysics

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Improvement of clinical wound microcirculation diagnosis using an object tracking-based laser speckle contrast imaging system

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APL Bioengineering 2024年第1期8卷 016105页

作者： Hsieh, Meng-Che Chang, Chia-Yu Hsu, Ching-Han Lin, Yan-Ren Hsieh, Pei-You Ching, Congo Tak-Shing Liao, Lun-De Institute of Biomedical Engineering and Nanomedicine National Health Research Institutes 35 Keyan Road Zhunan Town Miaoli County 35053 Taiwan Program in Tissue Engineering and Regenerative Medicine National Chung Hsing University 145 Xingda Road South District Taichung402 Taiwan Department of Biomedical Engineering and Environmental Sciences National Tsing Hua University No. 101 Section 2 Kuang-Fu Road Hsinchu30013 Taiwan Department of Emergency and Critical Care Medicine Changhua Christian Hospital Changhua Taiwan Graduate Institute of Biomedical Engineering National Chung Hsing University 145 Xingda Road South District Taichung402 Taiwan Department of Electrical Engineering National Chi Nan University 1 University Road Puli Township Nantou County 545301 Taiwan

Wound monitoring is crucial for effective healing, as nonhealing wounds can lead to tissue ulceration and necrosis. Evaluating wound recovery involves observing changes in angiogenesis. Laser speckle contrast imaging (LSCI) is vital for wound assessment due to its rapid imaging, high resolution, wide coverage, and noncontact properties. When using LSCI equipment, regions of interest (ROIs) must be delineated in lesion areas in images for quantitative analysis. However, patients with serious wounds cannot maintain constant postures because the affected areas are often associated with discomfort and pain. This leads to deviations between the drawn ROI and actual wound position when using LSCI for wound assessment, affecting the reliability of relevant assessments. To address these issues, we used the channel and spatial reliability tracker object tracking algorithm to develop an automatic ROI tracking function for LSCI systems. This algorithm is used to track and correct artificial movements in blood flow images, address the ROI position offset caused by the movement of the affected body part, increase the blood flow analysis accuracy, and improve the clinical applicability of LSCI systems. ROI tracking experiments were performed by simulating wounds, and the results showed that the intraclass correlation coefficient (ICC) ranged from 0.134 to 0.976. Furthermore, the object within the ROI affected tracking performance. Clinical assessments across wound types showed ICCs ranging from 0.798 to 0.917 for acute wounds and 0.628-0.849 for chronic wounds. We also discuss factors affecting tracking performance and propose strategies to enhance implementation effectiveness. © 2024 Author(s).

关键词： Image enhancement

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A Distributed Task Allocation Protocol for Cooperative Multi-UAV Search and Rescue Systems

A Distributed Task Allocation Protocol for Cooperative Multi...

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2021 International Conference on Unmanned Aircraft Systems, ICUAS 2021

作者： De Freitas, Edison Pignaton Basso, Maik Da Silva, Antonio Arlis Santos Vizzotto, Marcos Rodrigues Correa, Mateus Schein Cavalheiro Federal University of Rio Grande Do sul Graduate Program in Electrical Engineering Porto Alegre Brazil Federal University of Rio Grande Do sul Graduate Program in Computer Science Porto Alegre91.501-970 Brazil Federal University of Rio Grande Do sul Department of Electric Automation and Energy Porto Alegre Brazil

ISBN: (纸本)9780738131153

Nowadays, applications involving multiple robotic systems connected through a wireless network - to perform tasks together - have an increased research interest. Unmanned Aerial Vehicles (UAVs) are excellent tools for evaluating and surveying distributed robotic systems applications due to their flexibility and three-dimensional mobility capability. Cooperative systems composed of multiples UAVs may have a centralized coordination which assists the members of a team to make their decisions in a distributed manner regarding the tasks to be performed. This paper proposes a system composed of embedded hardware and a high-level communication protocol that serves as a basis for identifying, distributing, and allocating tasks in a simple and distributed way to be used by groups of UAVs. The proposal is evaluated in a search and rescue scenario. The setup is configured with two types of UAVs - namely, searchers (search for new tasks) and workers (execution of tasks). Also, a set of nine simulation experiments covering three different setups were performed. Then the proposal is evaluated by two sets of field experiments with real vehicles. The obtained results in the proposed experiments demonstrate that the system can be successfully used in the proposed scenario for task distribution and allocation. © 2021 IEEE.

关键词： Antennas

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Supervised Score-Based Modeling by Gradient Boosting

arXiv

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arXiv 2024年

作者： Zhao, Changyuan Du, Hongyang Liu, Guangyuan Niyato, Dusit College of Computing and Data Science Nanyang Technological University Singapore CNRS@CREATE 1 Create Way # 08-01 Create Tower 138602 Singapore Department of Electrical and Electronic Engineering University of Hong Kong Hong Kong The Energy Research Institute @ NTU Interdisciplinary Graduate Program Singapore

Score-based generative models can effectively learn the distribution of data by estimating the gradient of the distribution. Due to the multi-step denoising characteristic, researchers have recently considered combining score-based generative models with the gradient boosting algorithm, a multi-step supervised learning algorithm, to solve supervised learning tasks. However, existing generative model algorithms are often limited by the stochastic nature of the models and the long inference time, impacting prediction performances. Therefore, we propose a Supervised Score-based Model (SSM), which can be viewed as a gradient boosting algorithm combining score matching. We provide a theoretical analysis of learning and sampling for SSM to balance inference time and prediction accuracy. Via the ablation experiment in selected examples, we demonstrate the outstanding performances of the proposed techniques. Additionally, we compare our model with other probabilistic models, including Natural Gradient Boosting (NGboost), Classification and Regression Diffusion Models (CARD), Diffusion Boosted Trees (DBT), and non-probabilistic GBM models. The experimental results show that our model outperforms existing models in both accuracy and inference time. © 2024, CC BY.

关键词： Self-supervised learning

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Adaptive and Fair Deployment Approach to Balance Offload Traffic in Multi-UAV Cellular Networks

arXiv

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arXiv 2022年

作者： Lai, Chuan-Chi Bhola Tsai, Ang-Hsun Wang, Li-Chun The Department of Information Engineering and Computer Science Feng Chia University Taichung40724 Taiwan The Electrical Engineering and Computer Science International Graduate Program National Yang Ming Chiao Tung University Hsinchu30010 Taiwan The Department of Communications Engineering Feng Chia University Taichung40724 Taiwan The Department of Electrical and Computer Engineering National Yang Ming Chiao Tung University Hsinchu30010 Taiwan

Unmanned aerial vehicle-aided communication (UAB-BS) is a promising solution to establish rapid wireless connectivity in sudden/temporary crowded events because of its more flexibility and mobility features than conventional ground base station (GBS). Because of these benefits, UAV-BSs can easily be deployed at high altitudes to provide more line of sight (LoS) links than GBS. Therefore, users on the ground can obtain more reliable wireless channels. In practice, the mobile nature of the ground user can create uneven user density at different times and spaces. This phenomenon leads to unbalanced user associations among UAV-BSs and may cause frequent UAV-BS overload. We propose a three-dimensional adaptive and fair deployment approach to solve this problem. The proposed approach can jointly optimize the altitude and transmission power of UAV-BS to offload the traffic from overloaded UAV-BSs. The simulation results show that the network performance improves by 37.71% in total capacity, 37.48% in total energy efficiency and 16.12% in the Jain fairness index compared to the straightforward greedy approach. Copyright © 2022, The Authors. All rights reserved.

关键词： Energy efficiency

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Electrostatic Shield to Mitigate the High Frequency Circulating Bearing Current - A Study for Design Guidelines

Electrostatic Shield to Mitigate the High Frequency Circulat...

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Industrial Applications Society Annual Conference on Petroleum and Chemical Industry

作者： Marco T. A. Êvo Caio Eduardo Silva Isabela O. Zaparoli Hélder De Paula Electrical Engineering Department Federal University of São João del Rei São João del Rei MG Brazil Graduate Program in Electrical Engineering Federal University of Uberlândia Uberlândia MG Brazil Faculty of Electrical Engineering Federal University of Uberlândia Uberlândia MG Brazil

In a previous work, the authors addressed electrostatic shielding to reduce the bearing discharge currents (Electrostatic discharge machining currents - EDM). In order to expand the application of such a shielding device, this paper presents an analysis of its use to reduce the inverter-induced circulating bearing currents on induction machines. Employing finite element analysis (FEA), 2D and 3D models were developed to clarify the tradeoff between the shield effectiveness and the associated additional heat losses and motor efficiency reduction, considering different geometric arrangements and materials for the shielding device construction. The results provide very good guidelines for the shield design, contributing to its practical application viability. It is shown that it is possible to design a shielding configuration that achieves a high mitigating level with a negligible impact on the motor efficiency and developed torque. Furthermore, comparing calculation models of different complexities, the paper also shows the importance of representing all capacitive couplings inside the motor and the non-uniform current distribution in the shield to determine its effectiveness. Since a large fraction of the motor failures are caused by bearing currents, this paper can provide benefits to key topics for industry, such as equipment reliability and availability.

关键词：

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Qualitative Comparison between the Brazilian Labeling program for Buildings and the Portuguese Energy Certification System for Buildings:Proposals for Improving Brazilian Regulations

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Energy engineering 2021年第3期118卷 615-629页

作者： Jaime Francisco de Sousa Resende Andrea Lucia Teixeira Charbel Teresa Cristina Bessa Nogueira Assunção Graduate Program in Energy Engineering Federal University of São João del ReiSão João del ReiBrazil Department of Thermal and Fluid Sciences Federal University of São João del ReiSão João del ReiBrazil Department of Electrical Engineering Federal University of São João del ReiSão João del ReiBrazil

Buildings represent a significant share of the world’s energy consumption,and the sector has drawn the attention of governments,which have adopted policies to reduce energy *** Certifications of Energy Efficiency in Buildings stand out as one possible solution to achieve this goal,employed in several countries *** European Union presents advanced energy assessment programs for buildings,being a reference and model for several other regulations in the *** Energy Certification System for Buildings(SCE)of Portugal is considered a success case,reflected in the significant number of energy certificates *** Brazilian Labeling program for Building(PBE Edifica),first launched in 2009,does not find a broad application today in the Brazilian *** work shows a synthesis of the European Energy Performance of Buildings Directive(EPBD)and the Brazilian and Portuguese regulations’history.A qualitative comparison is made between the SCE and the PBE Edifica to verify a European and a developing country’s regulations with a certain degree of cultural and climatic *** this comparison,proposals are made for improvements to Brazilian certification,seeking to improve its energy planning and energy policy concerning its building *** suggestions for improvement presented may also be appropriate for other developing countries that have started and have not yet successfully implemented their energy certification programs in buildings.

关键词： Energy efficiency energy policy building labeling energy certification improvement proposals

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