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SSRN 2024年

作者： Peng, Xiaoqiang Huang, Guoliang Chen, Huan Duan, Qian Huang, Ke College of Materials Science & Engineering Sichuan University Chengdu610065 China Key Laboratory of Advanced Special Materials & Technology Ministry of Education Chengdu610065 China Sichuan University Jingwei Huacheng Additive Manufacturing Joint Laboratory Chengdu610065 China National Key Laboratory of Nuclear Reactor Technology Nuclear Power Institute of China Chengdu610213 China

Aspiration performance (K/Reff) is a crucial performance indicator of the wick. However, it is difficult to enhance the permeability (K) and capillary force (1/Reff) at the same time. A wick with a grooved and porous hybrid structure was fabricated using Laser Powder Bed Fusion (LPBF) to achieve superior liquid absorption performance. The grooved structure ensures excellent permeability (K), while the porous structure offers a high capillary force (1/Reff), which is further enhanced by the corner flow effect. The optimal structure, featuring a 0.6 mm square channel and 70.99% porosity, achieved an ultra-high liquid absorption performance of 3.24×10-6 m, which is 106.3% higher than the previously reported best value. This study introduces a novel design concept and preparation method for high-performance heat pipes. © 2024, The Authors. All rights reserved.

关键词： Heat pipes

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Experimental Study on the Characteristics of Annular Fluid Film in a Locally Deformed Narrow Rectangular Channel

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SSRN 2024年

作者： Wang, Fenze Ren, Quanyao Liu, Haidong Xiao, Yi Chen, Deqi Key Laboratory of Low-grade Energy Utilization Technologies and Systems Chongqing University Ministry of Education Chongqing400044 China Department of Nuclear Engineering and Technology School of Energy and Power Engineering Chongqing University Chongqing400044 China Science and Technology on Reactor System Design Technology Laboratory Chengdu610041 China Liangjiang International College Chongqing University of Technology Chongqing401135 China Chongqing Research Institute of HIT Chongqing401151 China School of Flight Technology Civil Aviation Flight University of China Sichuan618307 China China

The local deformation of plate fuel assembly due to neutron irradiation will lead to the deterioration of heat transfer in the flow channel. Studying the characteristics of annular flow films in narrow rectangular channels under localized deformation provides a foundation for understanding the heat and mass transfer and the hydrodynamic characteristics of the locally deformed narrow flow channel. In this study, the annular flow liquid film characterization experiments were conducted in a narrow rectangular channel under three conditions: no local deformation, ellipsoidal deformation, and pillow-shaped deformation. Various parameters of the annular flow liquid films, including liquid film thickness, disturbance wave height, and disturbance wave wavelength, were obtained using a high-speed camera acquisition system and advanced image processing techniques. The effects of flow conditions and local deformation on the liquid film parameters of each annular flow were analyzed. As the radial size of the local deformation increases relative to the liquid film thickness, the viscous bottom layer of the liquid film disintegrates, resulting in a reduction of the total liquid film thickness. When the gas-phase velocity is low, the local deformation exerts a greater shear force on the disturbance wave, prolonging the action time and increasing the likelihood of wave disintegration. Under conditions of no channel deformation, the disturbance wave wavelength is negatively correlated with the gas-phase velocity;conversely, under localized channel deformation, the wavelength is positively correlated with the gas-phase velocity. Thus, the effect of localized deformation on wavelength is bidirectional. Local deformation impact factor functions for liquid film thickness, disturbance wave height, and disturbance wave wavelength have been derived, with the error of these impact factor functions maintained within ±30%. © 2024, The Authors. All rights reserved.

关键词： Neutron irradiation

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Energy-Efficient Caching and User Selection for Resource-Limited SAGINs in Emergency Communications

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IEEE Transactions on Communications 2024年

作者： Wei, Qing Chen, Yingyang Jia, Ziye Bai, Wenle Pei, Tingrui Wu, Qihui North China University of Technology School of Information Beijing100144 China Jinan University College of Information Science and Technology Guangzhou510632 China Nanjing University of Aeronautics and Astronautics Key Laboratory of Dynamic Cognitive System of Electromagnetic Spectrum Space Ministry of Industry and Information Technology Nanjing211106 China Southeast University National Mobile Communications Research Laboratory Nanjing211111 China

The ever-increasing requests of users in emergency communication scenarios lead to high data traffic and transmission delay, posing challenges for resource-limited space-air-ground integrated networks (SAGINs). To address this issue, this paper proposes a joint caching optimization and user selection (JCOUS) problem that leverages unmanned aerial vehicle (UAV) caching to maximize the residual energy of the satellite, considering the limited resources of UAVs. To address the complex time-coupling optimization problem with discrete variables, we propose a primal decomposition method to decouple the problem, and design an energy-efficient user selection algorithm with dynamic caching. Furthermore, to reduce computational complexity and cost, we consider a statistical scenario and maximize the statistical residual energy in the JCOUS problem. Simulation results verify that the proposed scheme can achieve a higher residual energy and fast optimization, thus realizing energy saving and quick decision making especially in large-scale computation-intensive SAGINs. © 1972-2012 IEEE.

关键词： Unmanned aerial vehicles (UAV)

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Investigation of turbulent prt model and the segmentation rule for lbe turbulent heat transfer

Investigation of turbulent prt model and the segmentation ru...

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2020 International Conference on Nuclear Engineering, ICONE 2020, collocated with the ASME 2020 Power Conference

作者： Peiying, Li Jian, Deng Lei, Zhong Libo, Qian Rong, Cai Yugao, Ma Hongxing, Yu Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

ISBN: (纸本)9780791883785

With liquid metal like lead-bismuth alloy(LBE) acting as a coolant for nuclear reactors, it is necessary to use a more accurate heat transfer relationship and a more reliable Prt model for the low Pr fluid. Because of the low Pr of liquid metal, the thermal conductivity is more dominant than the momentum transfer, which is quite different from ordinary fluids. In this case, the turbulent Prt can better reflect the heat transfer process. In this study, the Prt=A1+A2/Pr form is selected, and the corresponding coefficients are obtained by the renormalization group analysis method, then corrected by Pr. Furthermore, the applicable range and segmentation rule of the turbulent Prt model are discussed, and the obtained Prt segmentation theoretical model is written into CFD. The result shows that, compared with the previously unmodified model, the radial temperature distribution and Nusselt number (Nu) of the annular and bundle channel obtained by RANS method with the improved Prt model is in good agreement with experimental results, and the deviations are within 5%. It is proved that the turbulent Prt segmentation theoretical model proposed in this study is effective and can represent the heat transfer characteristics of liquid metal from the mechanism. © 2020 American Society of Mechanical Engineers (ASME). All rights reserved.

关键词： Liquid metals

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An Ontology-based Knowledge Modeling towards Eco-design for Additive Manufacturing 31

An Ontology-based Knowledge Modeling towards Eco-Design for ...

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31st CIRP Conference on Life Cycle Engineering, LCE 2024

作者： Wang, Yanan Peng, Tao Kim, Samyeon Xiong, Yi Tang, Yunlong Tang, Renzhong State Laboratory of Fluid Power Components and Mechatronic Systems School of Mechanical Engineering Zhejiang University Hangzhou310058 China Department of Mechanical Engineering Jeonju University Jeonju-si Jeollabuk-do55069 Korea Republic of School of System Design and Intelligent Manufacturing Southern University of Science and Technology Shenzhen518055 China Mechanical and Aerospace Engineering Department Monash University Melbourne3800 Australia Materials Science and Engineering Department Monash University Melbourne3800 Australia Zhejiang Province Key Laboratory of Advanced Manufacturing Technology School of Mechanical Engineering Zhejiang University Hangzhou310058 China

Owing to the unique technological merits of additive manufacturing (AM), design for AM, particularly eco-design for AM, has been gaining attention in improving the sustainable performance of AM-fabricated (AMed) parts. The main challenge in harvesting potential sustainability benefits is how to capture the impact of design on sustainable performance. Though several existing studies adopted quantitative evaluation on AM sustainability and investigated the relationships between design information and sustainability information of AMed part, the sustainability information is still unavailable in the design phase. This hardly guides eco-design for AM in practice. To support the increasing industrial applications of AM, this paper illustrates related knowledge, that is, material-process-structure-ecoProperty (MPSeP) relationships to connect design and sustainability information in eco-design for AM. An ontology-based method is proposed to model the MPSeP relationships of the AMed part in a structured way. An example of an AMed hydraulic valve body was used to demonstrate the MPSeP modeling process. It is discussed that how the constructed model effectively assists AM designers through providing eco-design recommendation, and enables design software tools to perform sustainability analysis towards eco-design for AM. © 2024 The Author(s).

关键词： 3D printing

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Shifting Classification of Automatic Transmission Based on Shapelet Transform 4

Shifting Classification of Automatic Transmission Based on S...

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4th International Conference on Communications, Information system and Computer Engineering, CISCE 2022

作者： Zou, Wujun Wang, Ye Pu, Jiarong Zhong, Chaojie Tank Transmission National Defense Science and Technology Key Laboratory China Northern Vehicle Research Institute Beijing China Micromotor Design Institute AVIC Beijing Shuguang Aviation Electric Co. Ltd. Beijing China

ISBN: (数字)9781665498487

ISBN: (纸本)9781665498487

During the driving process of the vehicle, a large amount of time series containing shifting information was continuously generated. It is a laborious process to accurately detect the factory quality inspection and shifting characteristics of automatic transmissions through these data. In this context, this paper proposed a method to classify shifting data using shapelet transform, which is a local shape similarity classification method based on the most discriminative subsequence in a time series. In consideration of the low efficiency of traditional shapelet extraction methods, we introduce the idea of mathematical statistical probabilistic models into the extraction of shapelets. More specifically, we first build a probabilistic model of the training dataset and sample some time series from the training dataset by the utilization of distribution estimation algorithm (EDA). Then we use the probabilistic model update method to find discriminative subsequences in the time series as shapelet candidates. We next prune highly similar shapelet candidates through shapelet filters. Finally, we use the best k shapelets to convert each time series in the dataset into k corresponding features, which can be used in conjunction with traditional classifiers to classify the data. The automatic transmission shifting classification experiment shows that the shapelet discovery algorithm based on the probability model proposed in this paper can greatly improve the efficiency of the algorithm while ensuring the classification accuracy. © 2022 IEEE.

关键词： Classification (of information)

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Diffusion Model-based Metaverse Rendering in UAV-Enabled Edge Networks With Dual Connectivity

Diffusion Model-based Metaverse Rendering in UAV-Enabled Edg...

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IEEE Conference on Wireless Communications and Networking

作者： Guoquan Wu Jiangtian Nie Jianhang Tang Yuling Chen Yang Zhang Luchao Han Zehui Xiong School of Information Science and Engineering Yanshan University China School of Computer Science and Engineering Nanyang Technological University Singapore State Key Laboratory of Public Big Data Guizhou University China College of Computer Science and Technology Nanjing University of Aeronautics and Astronautics China National Natural Science Foundation of China China Pillar of Information Systems Technology and Design Singapore University of Technology and Design Singapore

ISBN: (数字)9798350303582

ISBN: (纸本)9798350303599

Metaverse is an immersive, seamless, interactive, comprehensive virtual world, as well as a replication, extension, and transcendence of the real world. Unmanned aerial vehicle (UAV)-enabled mobile edge computing (MEC) is becoming a key technology for ubiquitous Metaverse services. To enhance network resource utilization, we introduce dual connectivity (DC) technologies in UAV-enabled MEC, which increases the time complexity associated with resource management. Considering the specific features of DC communication channels, we propose a UAV-assisted Metaverse rendering problem to enhance the Metaverse service experience and reduce the energy cost of edge devices. To solve the rendering problem with low complexity, we propose a diffusion model-based Metaverse rendering algorithm, where a novel diffusion model is used to generate integer rendering decisions with the aid of the gradient provided by the model-based Metaverse rendering problem. Moreover, with the given rendering decisions, the communication and computation resource allocation results are derived by the model-based optimization method. Finally, we conduct extensive simulation experiments based on real-world datasets. Comprehensive simulation results demonstrate that the diffusion model-based Metaverse rendering algorithm can reduce the Metaverse frame rendering time and improve user experience.

关键词： Costs Metaverse Computational modeling system performance Rendering (computer graphics) Autonomous aerial vehicles User experience

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Small-Target Infrastructure Detection with Spatial Tracking and Multi-Level Feature Extraction of Railway Track Scenes

Small-Target Infrastructure Detection with Spatial Tracking ...

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Intelligent Communication, Sensing and Electromagnetics (ICSE), International Conference on

作者： Heng Du Huaiming Cang Yiwen Bai Xinyi Wang Beijing Elephant Technology Co. Ltd Beijing China School of Transportation Science and Engineering Beihang University Beijing China The State Key Lab of Intelligent Transportation System Beijing China Tianjin Key Laboratory for Advanced Mechanical System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology) Tianjin China

ISBN: (数字)9798350354935

ISBN: (纸本)9798350354942

In the field of railway transportation, with the continuous improvement of train running speed and the continuous increase of operating mileage, it becomes particularly important to ensure the safety and integrity of small-target infrastructure along the railway train. Although many small-target detection methods have been proposed, the research on small-target infrastructure detection along rail trains is very rare. To solve this problem, this paper proposes a small-target infrastructure detection network with spatial tracking and multi-level feature extraction based on Yolov8n. The experimental results show that ST-YOLO has a 3.6% mAP improvement on the OSDaR23 dataset compared to the baseline Yolov8n, and shows significant advantages over other state-of-the-art methods.

关键词： Rails Transportation Railway safety Switches Feature extraction Rail transportation Real-time systems Sensors Safety Monitoring

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Sensitivity Study of Thermal Hydraulics to Corrosion of Heat Exchange Tubes in Steam Generator

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SSRN 2022年

作者： Wang, Weibing Cheng, Kun Wang, Bo Zhang, Meng Tian, Ruifeng College of Nuclear Science and Technology Harbin Engineering University Harbin150001 China Heilongjiang Provincial Key Laboratory of Nuclear Power System & Equipment Harbin Engineering University Harbin150001 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

A leakage accident occurs in the circulating water system in PWRs, impurity ions enter the SG with the secondary circuit feed water and cause electrochemical corrosion of the heat transfer tubes(HTTs). Based on the hide out and return mathematical model in the SG, a coupled mathematical model of mass transfer-electromigration-hydrodynamics of impurity ions in the secondary boiling channel of SG is deduced. The accuracy of the mathematical model is verified by experiments, and the effects of heat flux density ( Pe q ), flow velocity ( Pe u ), impurity ion concentration ( Pe c ) and relative solubility of impurity ions ( K p ) on impurity ions migration and electrochemical corrosion are analyzed and discussed. The results show that P e q mainly controls the diffusion of impurity ions and thus affects the migration rate of impurity ions, and the mass transfer of impurity ions driven by Pe q can enhance the reduction of H + , thereby accelerating the corrosion rate of HTTs. The synergistic effect of convective mass transfer and electromigration during impurity ions migration is mainly affected by Pe u , and the electrochemical corrosion of the surface of HTTs is mainly controlled by charge transfer with the increase of Pe u . The Pe c on the surface of HTTs changes linearly with time, and the corrosion rate increases with the increase of Pe c . The corrosion rate of HTTs is proportional to K p , and K p is a main factor that causes different corrosion rates in different location of HTTs. In this paper, a coupled model for the sensitivity of thermal-hydraulic parameters ( Pe q , Pe u , Pe c and K p ) in SG to electrochemical corrosion of HTTs is proposed for the first time. The research results can provide important support for the development of corresponding response strategies, schemes for the life prediction of HTTs and the safety maintenance of nuclear power plants. © 2022, The Authors. All rights reserved.

关键词： Steam generators

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Experimental study on the energy loss from flow and electrical of vanadium battery with constant pump frequency 2

Experimental study on the energy loss from flow and electric...

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2023 2nd International Conference on New Energy, Energy Storage and Power Engineering, NESP 2023

作者： Sun, Yanzhao Zou, Tao Li, Dianhong Li, Juntao School of Electrical Engineering and Automation Wuhan University Hubei Wuhan430072 China Big Pawer Electrical Technology Xiangyang Co. Ltd. Hubei Xiangyang441057 China Hubei Key Laboratory of Power System Design and Test for Electrical Vehicle Hubei University of Arts and Science Hubei Xiangyang441053 China Hunan Vanadium Valley New Energy Technology Co. Ltd. Hunan Changsha410116 China

When the vanadium battery was running, pump frequency and current density were two frequently adjusted parameters. When the pump frequency was constant, the main flow-electrical parameter variation needs to be further studied. To this end, a 10 kW vanadium battery was built. When the current density was relatively high during the charge-discharge, the flow-electrical parameters of the cathode and anode including the temperature, flow resistance, turning voltage difference, capacity loss, energy loss and energy efficiency were studied. Besides, the compositions of capacity and energy were introduced, and the loss calculation scheme was proposed. Firstly, in flow analysis, the flow resistance was defined, which represents the flow state of the electrolyte. It was found that the flow resistance was nearly linear with the temperature. Secondly, in electric analysis, the turning voltage difference increased with the current density increasing. For the same current density, the total energy loss of charge was less than the discharge, and the energy loss of bypass was less than the internal resistance. With the current density increasing, the energy efficiency decreased. The research can be provided insight into the optimizing operation for the vanadium battery. © Published under licence by IOP Publishing Ltd.

关键词： Current density

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