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SSRN 2024年

作者： Wang, Renzong Xiong, Yucheng Yang, Juekuan Liu, Zhichun Li, Shouhang Chen, Ge Liu, Xiangjun Institute of Micro/Nano Electromechanical System College of Mechanical Engineering Donghua University Shanghai201620 China School of Mechanical Engineering Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments Southeast University Nanjing210096 China School of Energy and Power Engineering Huazhong University of Science and Technology Wuhan430074 China

Amorphous interfaces/contacts are ubiquitous in numerous micro/nanoelectronic devices and functional composite materials. Traditionally, the thermal resistance of interfaces/contacts was believed to be the primary impediment to heat transport. However, in this study, through measuring thermal resistance between crystalline-amorphous core-shell Ge nanowires, we unveil an ultrahigh thermal conductance across the point contact between the amorphous shell of Ge nanowires with a room-temperature value of 892 MW/m2-K. This value surpasses the typical values observed in point contacts between crystalline nanowires/nanoribbons by one to three orders of magnitude and even exceeds that of epitaxial interfaces between well-lattice-matched materials. Molecular and lattice dynamic simulations further reveal that the observed ultrahigh thermal conductance is attributed to the broadened vibrational bandwidths within the amorphous contact, which facilitates the redistribution of phonon energy into a state conductive to more effective interfacial energy transmission, leading to an enhanced overlap of phonon modes and, consequently, a heightened thermal conductance. © 2024, The Authors. All rights reserved.

关键词： Heat conduction

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Field-Harmonic-Oriented design of Vernier Permanent Magnet Machine Towards High Torque Density and Low Torque Ripple

Field-Harmonic-Oriented Design of Vernier Permanent Magnet M...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Li Fang Dawei Li Yuanzhi Zhang Jiewen Wu School of Electrical and Electronics Engineering Huazhong University of Science and Technology Wuhan China School of Electricla Engineering and Automation (Hubei Key Laboratory of Power Equipment and System Security for Integrated Energy) Wuhan University Wuhan China College of Design and Engineering National University of Singapore Singapore

Vernier permanent magnet machine (VPMM) has been a promising candidate for low-speed large-torque applications owing to high torque density based on multiple-magnetic field-harmonics working principle However, rich field harmonics also cause large torque ripple, meanwhile the regular reducing methods will also undermine torque density. In this paper, the field-harmonic-oriented design approach is proposed for the VPMM towards high torque density and low torque ripple. Based on the permeance unit model, the mapping relationship between torque output and field harmonics is built. Explicit design regulations are established for the airgap structure so as to modulate the optimal field harmonics composition. Via the proposed method, a surface-mounted VPMM is purposely designed and the electromagnetic performance is verified by FEA. Finally, a prototype of the proposed machine has been manufactured and tested. Both analytical and experimental results validate the feasibility of the proposed design method.

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A novel paper-based electrowetting device using cellulose paper and paraffin wax 26

A novel paper-based electrowetting device using cellulose pa...

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26th International Conference on Miniaturized systems for Chemistry and Life sciences, MicroTAS 2022

作者： Li, He Yan, Zhibin Jin, Mingliang Zhou, Guofu Shui, Lingling Guangdong Provincial Key Laboratory of Optical Information Materials and Technology Institute of Electronic Paper Displays South China Academy of Advanced Optoelectronics South China Normal University Guangzhou510006 China Defense Key Disciplines Lab of Novel Micro-nano Devices and System Technology Chongqing University Chongqing400044 China School of Information and Optoelectronic Science and Engineering South China Normal University Guangzhou510006 China Guangdong Shunde Innovative Design Institute Guangdong Foshan528318 China

ISBN: (纸本)9781733419048

Paper-based microfluidic devices based on continuous-flow (μPAD) and electrowetting on dielectric (EWOD), have attracted increasing attention due to their low cost and excellent liquid handling capability. Here, we report a novel paper-based EWOD devices fabricated with the cellulose paper as substrate and paraffin wax as dielectric layer, which have been widely used in μPAD. Two methods are proposed to fabricate paraffin wax layer, including melting and spray-coating. Under DC electric field, the spray-coating-based devices show larger contact angle changes but with smaller hysteresis than the melting-based one. Our study opens up a new way for fabrication of the hybrid paper-based microfluidic device in the future. © 2022 MicroTAS 2022 - 26th International Conference on Miniaturized systems for Chemistry and Life sciences. All rights reserved.

关键词： Wetting

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Effects of Wall Emissivity on Aerodynamic Heating in Scramjets

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Fluid Dynamics & Materials Processing 2020年第6期16卷 206-216页

作者： Yue Zhou Pengfei Ju School of Aeronautical Science and Technology Beihang UniversityBeijing100191China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical EngineeringTianjin University of TechnologyTianjin300384China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education(Tianjin University of Technology) Tianjin300384China

The effects of the wall emissivity on aerodynamic heating in a scramjet are *** supersonic turbulent combustion flow including radiation is solved in the framework of a decoupled strategy where the flow field is determined first and the radiation field *** particular,a finite difference method is used for solving the flow while a DOM(iscrete ordinates method)approach combined with a WSGGM(weighted sum of gray gases)model is implemented for radiative *** nonreactive turbulent channel flows are examined for a DLR hydrogen fueled scramjet changing parametrically the wall *** results indicate that the wall radiative heating rises greatly with increasing the wall *** the wall emissivity rises,the radiative source and total absorption increase,while the incident radiation decreases ***,although the radiative heating can reach a significant level,its contribution to the total aerodynamic heating is relatively limited.

关键词： Scramjet aerodynamic heating wall emissivity radiation

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A Train Cooperative Operation Optimization Method Considering Passenger Comfort based on Reinforcement Learning 11

A Train Cooperative Operation Optimization Method Considerin...

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11th IEEE Data Driven Control and Learning systems Conference, DDCLS 2022

作者： Wang, Xingguo Wu, Yue Huang, Deqing Zhu, Lei Lu, Zheng He, Yan Institute of System Science and Technology School of Electrical Engineering Southwest Jiaotong University Chengdu611756 China Southwest Jiaotong University Key Laboratory of Advanced Energy Traction Comprehensive Energy Saving Railway Industry Chengdu610031 China School of Computing and Artificial Intelligence Southwest Jiaotong University Chengdu611756 China School of Design Arts Southwest Jiaotong University Chengdu610031 China

ISBN: (数字)9781665496759

ISBN: (纸本)9781665496759

This paper mainly focuses on the high-speed train cooperative operation problem, considering passenger comfort. To solve this problem, a speed curve optimization method based on Reinforcement Learning algorithm is proposed. First, according to the train dynamics system, we build the speed curve optimization object. For realizing the train cooperative operation and increasing the passenger comfort, trains distance constraint and jerk rate constraint are fully considered in formulating reward function. And then, agent of Twin Delayed Deep Deterministic Policy Gradient (TD3) is established. Based on TD3 algorithm, two groups of Q-value networks and one group of action action networks have the same structure, different initial values and update rates respectively, which improves the stability and convergence speed of the algorithm. After the training. The Agent can generate a desirable speed curve of train based on constraints of vehicle output and jerk rate under cooperative operation. © 2022 IEEE.

关键词： Speed

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Link Budget Calculation for LoRa-band Remoting Sensing Satellite

Link Budget Calculation for LoRa-band Remoting Sensing Satel...

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IEEE International Symposium on Electromagnetic Compatibility (EMC-Beijing)

作者： Shurui Wang Xiang Zhang Xiaojun Hao Shuaige Gong Chong Li Qian Xu Lei Xing College of Electronic and Information Engineering Nanjing University of Aeronautics and Astronautics Nanjing China College of Mechanical Engineering (Aircraft design and engineering) Nanjing University of Science and Technology Nanjing China State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System (CEMEE) Luoyang China

Small satellites are increasingly attracting the attention of the industry for its many aspects of advantages. We proposed a communication subsystem for commercial remote sensing satellite. The interface between the communication system and other modules on the satellite and the communication protocol are briefly introduced. In order to make sure that the satellite-to-ground link is reliable, we calculate the link budget at 471 MHz for LEO small satellite. Additionally, the transmission power and reception sensitivity is 17 dBm and −123 dBm respectively. The result shows that the proposed subsystem is reliable in RF performance and can be used in other commercial satellite in the future.

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Reshaping the ISAC Tradeoff Under OFDM Signaling: A Probabilistic Constellation Shaping Approach

arXiv

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arXiv 2023年

作者： Du, Zhen Liu, Fan Xiong, Yifeng Han, Tony Xiao Eldar, Yonina C. Jin, Shi The School of Electronic and Information Engineering Nanjing University of Information Science and Technology Nanjing China School of System Design and Intelligent Manufacturing Southern University of Science and Technology Shenzhen China The School of Information and Electronic Engineering Beijing University of Posts and Telecommunications Beijing China Huawei Technologies Co. Ltd Shenzhen China The Faculty of Mathematics and Computer Science Weizmann Institute of Science Rehovot Israel National Mobile Communications Research Laboratory Southeast University Nanjing210096 China

Integrated sensing and communications is regarded as a key enabling technology in the sixth generation networks, where a unified waveform, such as orthogonal frequency division multiplexing (OFDM) signal, is adopted to facilitate both sensing and communications (S&C). However, the random communication data embedded in the OFDM signal results in severe variability in the sidelobes of its ambiguity function (AF), which leads to missed detection of weak targets and false detection of ghost targets, thereby impairing the sensing performance. Therefore, balancing between preserving communication capability (i.e., the randomness) while improving sensing performance remains a challenging task. To cope with this issue, we characterize the random AF of OFDM communication signals, and demonstrate that the AF variance is determined by the fourth-moment of the constellation amplitudes. Subsequently, we propose an optimal probabilistic constellation shaping (PCS) approach by maximizing the achievable information rate (AIR) under the fourth-moment, power and probability constraints, where the optimal input distribution may be numerically specified through a modified Blahut-Arimoto algorithm. To reduce the computational overheads, we further propose a heuristic PCS approach by actively controlling the value of the fourth-moment, without involving the communication metric in the optimization model, despite that the AIR is passively scaled with the variation of the input distribution. Numerical results show that both approaches strike a scalable performance tradeoff between S&C, where the superiority of the PCS-enabled constellations over conventional uniform constellations is also verified. Notably, the heuristic approach achieves very close performance to the optimal counterpart, at a much lower computational complexity. Copyright © 2023, The Authors. All rights reserved.

关键词： Orthogonal frequency division multiplexing

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Research on in-plane fluid-elastic instability of heat transfer tube in steam generator 48

Research on in-plane fluid-elastic instability of heat trans...

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48th International Congress and Exhibition on Noise Control Engineering, INTER-NOISE 2019 MADRID

作者： Qi, Huan-Huan Jiang, Nai-Bin Huang, Xuan Feng, Zhi-Peng Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China 328 Changshun Avenue Chengdu China

ISBN: (纸本)9788487985317

Due to a small gap between the anti-vibration bars (AVBs) and the heat transfer tubes, and according to the position of AVBs and the number of continuous failures of the in-plane support, the in-plane restraint failure analysis of AVB is divided into 13 cases. The influence of the restraint failure on the in-plane mode of the heat transfer tube under different cases is analysed. The mode damping ratio was calculated by performing a weighted average method based on the mode shape function, and then the effects of different restraints by AVBs on fluid-elastic instability of steam generator tubes are studied. The analysis results show that with the increase of the continuous failure position of the in-plane support, the first-order modal frequency in the elbow zone decreases continuously, and the mode shape appearing in the elbow zone becomes more obvious. The first-order mode in the elbow zone is not necessarily the mode in which the largest fluidelastic instability ratio occurs. The vibration mode with the largest ratio of the fluid-elastic instability appears almost in the elbow zone. With the increase of the continuous failure position of the in-plane support, the fluid-elastic instability ratio increases continuously. When three or more continuous AVBs fail in-plane, fluidelastic instability will occur. © INTER-NOISE 2019 MADRID - 48th International Congress and Exhibition on Noise Control Engineering. All Rights Reserved.

关键词： Tubes (components)

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Microresonator Frequency Comb-Based Transmission of Intensity Modulated Direct Detection Data

Microresonator Frequency Comb-Based Transmission of Intensit...

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Conference on Lasers and Electro-Optics (CLEO)

作者： Peng Xing George F. R. Chen Hongwei Gao Xavier Chia Anuradha M. Agarwal Lionel C. Kimerling Dawn T. H. Tan Photonics Devices and System Group Singapore University of Technology and Design Singapore Singapore Microphotonics Center Massachusetts Institute of Technology Cambridge Massachusetts USA Materials Research Laboratory Massachusetts Institute of Technology Cambridge Massachusetts USA Department of Materials Science and Engineering Massachusetts Institute of Technology Cambridge Massachusetts USA Institute of Microelectronics A*STAR Singapore Singapore

We demonstrate high-speed transmission of 30Gbaud NRZ and PAM4 data using a silicon nitride microresonator frequency comb. We achieve bit-error-rates below the FEC limit and a low power penalty of 0.1dB compared to B2... 详细信息

ISBN: (数字)9781957171050

ISBN: (纸本)9781665466660

关键词： Optical fibers Industries Electric potential Frequency modulation Silicon nitride Microcavities Transceivers

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On Corrosion of Zirconium Alloy in Dissolved Oxygen Water：The Role of Cu Addition

SSRN

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SSRN 2023年

作者： Huang, Zongwen Liu, Qingdong Zheng, Fengxin Peng, Jianchao Yu, Yixiao Zeng, Qifeng Li, Qiang Zhao, Yi Institute of Materials Shanghai University Shanghai200072 China School of Material Science and Engineering Shanghai Jiao Tong University Shanghai200240 China Laboratory for Microstructures Shanghai University Shanghai200444 China Shanghai Nuclear Engineering Research & Design Institute Co. Ltd Shanghai200233 China Science and Technology on Reactor Fuel and Materials Laboratory Nuclear Power Institute of China Sichuan Chengdu610213 China

It is of significantly important to improve the corrosion resistance of Zr-Sn-Nb alloys in dissolved oxygen (DO) high temperature water by compositional modification. Here, the effect of Cu addition on the corrosion behaviors of Zr-0.5Sn-0.2Nb-0.4Fe-0.2Cr alloy was studied by using an autoclave circulating water loop at 360℃/20MPa up to 250 days. The oxide microstructures were characterized by a combination of SEM, TEM, STEM-EELS and PED. The results showed that compared with 0Cu alloy and 0.07Cu alloy, 0.13Cu alloy shows better corrosion resistance and its final weight gain after 250 days exposure is even lower than that of commercial Zr-4 alloy. The oxides for 0.07Cu and 0.13Cu alloys are more orderly arranged and thinner with less lateral cracks, and the columnar grains show a stronger {10-3} texture, than the Cu-free counterpart. The t-Zr2Cu SPPs have oxidized in the oxygen-rich layer below the O/M interface. The Cu ions tend to diffuse towards the grain boundary of dense columnar grains and maybe strengthen the grain boundaries, avoiding the defect generation under intrinsic stress in the oxide. © 2023, The Authors. All rights reserved.

关键词： Copper corrosion

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