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arXiv 2022年

作者： Liu, Yang Zhu, Hongen Lv, Haifeng Guo, Yuqiao Zhao, Yingcheng Lin, Yue Tai, Xiaolin Zhao, Jiyin Yuan, Bingkai Liu, Yi Zhang, Guobin Sun, Zhe Wu, Xiaojun Xie, Yi Wu, Changzheng School of Chemistry and Materials Science CAS Center for Excellence in Nanoscience CAS Key Laboratory of Mechanical Behavior and Design of Materials University of Science and Technology of China Hefei230026 China National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei230026 China Institute of Energy Hefei Comprehensive National Science Center Anhui Hefei230031 China

Excitonic insulators are long-sought-after quantum materials predicted to spontaneously open a gap by the Bose condensation of bound electron-hole pairs, namely, excitons, in their ground state1-3. Since the theoretical conjecture, extensive efforts have been devoted to pursuing excitonic insulator platforms for exploring macroscopic quantum phenomena in real materials. Reliable evidences of excitonic character have been obtained in layered chalcogenides as promising candidates4-9. However, owing to the interference of intrinsic lattice instabilities4,8-10, it is still debatable whether those features, such as charge density wave and gap opening, are primarily driven by the excitonic effect or by the lattice transition. Herein, we develop a novel charge-transfer excitonic insulator in organic‒inorganic superlattice interfaces, which serves as an ideal platform to decouple the excitonic effect from the lattice effect. In this system, we observe the narrow gap opening and the formation of a charge density wave without periodic lattice distortion, providing visualized evidence of exciton condensation occurring in thermal equilibrium. Our findings identify spontaneous interfacial charge transfer as a new strategy for developing novel excitonic insulators and investigating their correlated many−body physics. Copyright © 2022, The Authors. All rights reserved.

关键词： Charge density waves

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Data-driven modeling fast-slow coupling delayed dynamics using noisy data and sparse enhancement

Data-driven modeling fast-slow coupling delayed dynamics usi...

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International Conference on Industrial Artificial Intelligence (IAI)

作者： Huifang Tang Yuqiang Wu Yingming Dong Cheng Cheng Xiuting Li College of Science Huazhong Agricultural University Wuhan China School of Artificial Intelligence and Automation Huazhong University of Science and Techonology Wuhan China Yunnan Key Laboratory of Mechatronics Applied Technology Yunnan Mechanical Research and Design Institute of Machinery Research Institute Group Yunnan China Autonomous Intelligent Unmanned System Engineering Research Center Ministry of Education of China Huazhong University of Science and Technology Wuhan China

In this work, we focus on fast-slow delayed dynamical systems, which are usually described by coupled delayed differential equations with two-time scales. The purpose of this article is to propose a data-driven discovery method to identify the fast-slow delayed differential equations from noisy measurements. The proposed method blends delay dictionary-based sparse identification of nonlinear dynamics (SINDy) framework and a fixed interval sampling strategy. Specifically, we leverage the SINDy methodology to describe the fast-slow delayed differential equations by a few active terms of a large dictionary containing the delay terms and many candidate nonlinear basis functions. To identify the active terms and the corresponding coefficients, a sequential thresholded re-weighted ℓ 2 least squares algorithm is used to solve the resulting sparse regression problem to enhance the sparsity. Once a sparse model with fixed delay is selected, the proposed method further estimates the delayed time by calculating the reconstruction error from the sparse model until the one that makes the reconstruction error minimum. We verify the effectiveness of the proposed method with several classical fast-slow coupling delayed systems. The experimental results show that the proposed method can well automate the fast-slow delayed differential equations from noisy data and the delayed terms also can be detected accurately.

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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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Fluoride-Salt-Cooled High-Temperature reactor: An Integrated Nuclear-Based Energy Production and Conversion system

SSRN

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SSRN 2023年

作者： Zhang, Dalin Li, Xinyu Jiang, Dianqiang Zhou, Xingguang Lv, Xindi Yun, Shichang Wu, Wenqiang He, Xuanang Li, Haoyang Min, Xin Chen, Kailong Tian, Wenxi Qiu, Suizheng Su, Guanghui Zhao, Quanbin Fu, Yao Tang, Chuntao Zhuo, Wenbin Li, Jinggang Zuo, Jiaxu State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai201800 China Shanghai Nuclear Engineering Research & Design Institute Co. Ltd. Shanghai200233 China CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology Nuclear Power Institute of China Chengdu610213 China China Nuclear Power Technology Research Institute Guangdong Shenzhen518000 China Nuclear and Radiation Safety Center Ministry of Ecology and Environment Beijing100082 China

Based on the analysis of energy structure and the development trends of advanced nuclear energy technology, combining the complementary advantages of nuclear energy and other energy sources in China, the Fluoride-salt-cooled High-temperature reactor(FuSTAR) system has been proposed. FuSTAR system is designed to address production capacity issues in areas with energy shortages or resource concentration and can be combined with high-temperature process heat to achieve high-value-added processes such as hydrogen production. In this paper, the design and optimization processes of FuSTAR are described from three aspects: the neutronic and thermal-hydraulic system, the thermal transport system, and the power cycle system. Tri-structural isotropic fuel combined with helical cruciform elements has been studied in detail on the neutron physics and thermal-hydraulic properties, and the flow and heat transfer experiment is carried out for the first time. The multilayer nonlinear programming method has been applied to the design of thermal transport systems and the passive residual heat removal system and proved to be fast and efficient. Then the optimal parameters and configuration of the thermoelectric conversion system are obtained directly by using the superstructure optimization method, which saves computing resources greatly. Based on the above design and parameters, the inherent safety of FuSTAR is demonstrated through deterministic safety analysis. In addition, the iodine-sulfur cycle technology is also designed and analyzed, and the characteristics of tritium production in FuSTAR are calculated. The research provides important guidance for the detailed design and operation of FuSTAR. Moreover, this study highlights the significant potential of integrating nuclear energy with other energy sources in an optimized energy-production system. Based on the current research findings, prospects for future research directions are also suggested. © 2023, The Authors. All rights r

关键词： High temperature reactors

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Subgraph Matching with Diversity Handling and Its Applications to PCB Placement

Subgraph Matching with Diversity Handling and Its Applicatio...

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Electronics design Automation (ISEDA), International Symposium of

作者： Chuandong Chen Haiming Lin Miaodi Su Huan He Jianli Chen Ziran Zhu College of Physics and Information Engineering Fuzhou University Fuzhou China Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou China Hangzhou Huawei Enterprises Telecommunication Technologies Co. Ltd Hangzhou China State Key Lab of ASIC & System Fudan University Shanghai China National ASIC System Engineering Center Southeast University Nanjing China

ISBN: (数字)9798350352030

ISBN: (纸本)9798350352047

Printed circuit board (PCB) placement is a critical stage in industrial chip design, which still heavily relies on manual methods, leading to substantial design time consumption. Given the frequent occurrence of similar or identical modules in different PCB designs, the reuse of placements emerges as a promising avenue to enhance the efficiency of PCB placement. In this paper, we propose a sub graph matching based reference placement algorithm to achieve PCB placement reuse, thereby improving placement efficiency. We first take the netlist of the already placed and unplaced circuits as input and abstract them into graphs. Then, we construct and filter candidate spaces based on the characteristics of components and nets. In the process of filtering candidate spaces, we adopt diversity handling that includes cut edges and block nodes to ensure the proposed algorithm can handle inexact matching. Finally, we introduce virtual nodes to construct a matching tree using a combination of depth-first search (DFS) and breadth-first search (BFS), and then perform hierarchical matching based on this matching tree to complete the sub graph matching and obtain the placement results. Experimental results show that in large-scale PCB cases, our algorithm runs much faster than the state-of-the-art works. Particularly, the matching rate of our algorithm is almost 100% for the tested cases.

关键词： Matched filters design automation Filtering Printed circuits Diversity reception DH-HEMTs Manuals

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An Overview of Bearing Candidates for the Next Generation of Reusable Liquid Rocket Turbopumps

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Chinese Journal of Mechanical Engineering 2020年第2期33卷 43-55页

作者： Jimin Xu Changhuan Li Xusheng Miao Cuiping Zhang Xiaoyang Yuan Institute of Tribology School of Mechanical EngineeringHefei University of TechnologyHefei 230009China Aerospace Propulsion Institute China Aerospace Science and Technology CorporationXi’an 710100China Science Technology on Combustion Internal Flow and Thermal‑structure LaboratoryNorthwestern Polytechnical UniversityXi’an 710012China Superconducting Materials Research Center Laboratory Northwest Institute for Non-ferrous Metal ResearchXi’an 710016China Key Laboratory of Education Ministry for Modern Design and Rotor‑Bearing System Xi’an Jiaotong UniversityXi’an 710049China

There is a consensus in the aerospace field that the development of reusable liquid rockets can effectively reduce the launch *** pursuit of a long service life and reutilization highly depends on the bearing ***,the rolling element bearings(REBs)used in the existing rocket turbopumps present obvious and increasing limitations due to their mechanical contacting *** REBs,high rotational speed and long service life are two performance indexes that mutually restrict each *** go beyond the DN value(the product of the bearing bore and rotational speed)limit of REBs,the major space powers have conducted substantial explorations on the use of new types of bearings to replace the *** review discusses,first,the crucial role of bearings in rocket turbopumps and the related structural improvements of ***,with the prospect of application to the next generation of reusable liquid rocket turbopumps,the bearing candidates investigated by major space powers are summarized *** promising alternatives to REBs include fluid-film,foil,and magnetic bearings,together with the novel superconducting compound bearings recently proposed by our *** more than ten years of relevant research on fluid-film and magnetic bearings are also *** review is meaningful for the development of long-life and highly reliable bearings to be used in future reusable rocket turbopumps.

关键词： Aerospace Reusable liquid rocket turbopumps Rolling element bearings Bearing candidates Review

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Enhancing Irradiation Resistance in Refractory Medium Entropy Alloys with Simplified Chemistry

arXiv

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arXiv 2024年

作者： Tunes, M.A. Parkison, D. Sun, B. Willenshofer, P. Samberger, S. Derby, B.K. Baldwin, J.K.S. Fensin, S.J. Sobieraj, D. Wróbel, J.S. Byggmästar, J. Pogatscher, S. Martinez, E. Nguyen-Manh, D. El-Atwani, O. Chair of Non-Ferrous Metallurgy Montanuniversität Leoben Austria Materials Science and Technology Division Los Alamos National Laboratory United States Department of Nuclear Engineering University of California at Berkeley United States Departments of Mechanical Engineering and Materials Science and Engineering Clemson University United States Center for Integrated Nanotechnologies Los Alamos National Laboratory United States Faculty of Materials Science and Engineering Warsaw University of Technology Poland Department of Physics University of Helsinki Finland Materials Division United Kingdom Atomic Energy Authority Culham Campus Abingdon United Kingdom Department of Materials University of Oxford Parks Road United Kingdom Reactor Materials and Mechanical Design Pacific Northwest National Laboratory United States

Refractory High-Entropy Alloys (RHEAs) hold promising potential to be used as structural materials in future nuclear fusion reactors, where W and its alloys are currently leading candidates. Fusion materials must be able to withstand extreme conditions [1, 2], such as (i) severe radiation-damage arising from highly-energetic neutrons, (ii) embrittlement caused by implantation of H and He ions, and (iii) exposure to extreme high-temperatures and thermal gradients. Recent research demonstrated that two RHEAs - the WTaCrV [3] and WTaCrVHf [4] - can outperform both coarse-grained and nanocrystalline W in terms of its radiation response and microstructural stability [5-8]. Chemical complexity and nanocrystallinity enhance the radiation tolerance of these new RHEAs, but their multi-element nature, including low-melting Cr, complicates bulk fabrication and limits practical applications. Herein, we demonstrate that reducing the number of alloying elements and yet retain high-radiation tolerance is possible within the ternary system W-Ta-V via synthesis of two novel nanocrystalline refractory medium-entropy alloys (RMEAs): the W53Ta44V3 and W53Ta42V5 (in at.%). We experimentally show that the radiation response of the W-Ta-V system can be tailored by small additions of V, and such experimental result was validated with theoretical analysis of chemical short-range orders (CSRO) from combined ab-initio atomistic Monte-Carlo modeling. It is predicted from computational analysis that a small change in V concentration has a significant effect on the Ta-V CRSO between W53Ta44V3 and W53Ta42V5 leading to radiation-resistant microstructures in these RMEAs from chemistry stand-point of views. By returning to terminal solid solutions, we deviate from the original high-entropy alloy concept to show that high radiation resistance can be achieved in systems with simplified chemical complexity, hinting at a new paradigm for the metallurgy of high-entropy and highly-concentrated multi-compo

关键词： Tantalum alloys

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TSU: A Two-stage update approach for persistent skiplist 13th

TSU: A Two-stage update approach for persistent skiplist

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13th Conference on Advanced Computer Architecture, ACA 2020

作者： Wang, Shucheng Cao, Qiang Wuhan National Laboratory for Optoelectronics Key Laboratory of Information Storage System Engineering Research Center of Data Storage Systems and Technology School of Computer Science and Technology Huazhong University of Science and Technology Ministry of Education of China Wuhan China

ISBN: (纸本)9789811581342

Skiplist, a widely used in-memory index structure, could incur crash inconsistency when running on emerging NVRAM (Non-Volatile Random Access Memory). Logging or strict serialization can ensure crash consistency at the cost of severe performance degradation. In this paper, we propose TSU, a Two-stage update approach to improve the performance of persistent skiplist while preserve crash consistency. TSU exploits space locality of skiplist and atomic write of NVRAM, thus effectively reducing expensive cache line flush (clflush) operations. To this end, we category all four crash inconsistent states into two types: recoverable and unrecoverable. TSU could guarantee the crash state is recoverable by constraining the memory access order for insertion and deletion. We further design a persistency algorithm to reduce clflush by preserving the memory persistent order of skiplist update. In addition, we develop a concurrent search for TSU. The evaluation result shows that TSU can reduce cache line flush with up to 47.6%, and decrease the average request latency by up to 36% for insertions compared to the strict serialization. © Springer Nature Singapore Pte Ltd 2020.

关键词： Cache memory

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Optimal design for a High Power Transit Time Oscillator at X-band

Optimal Design for a High Power Transit Time Oscillator at X...

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Progress in Electromagnetic Research Symposium (PIERS)

作者： Zhongwu Xiang Jin Meng Danni Zhu Chaochao Yang Liyang Huang Yuzhang Yuan Haitao Wang Kang Luo Jiangfeng Han National Key Laboratory of Science and Technology on Vessel Integrated Power System Naval University of Engineering Wuhan China

ISBN: (纸本)9781665409889

Considering the lightweight scheme and high-efficiency characteristic of the transit time oscillator (TTO), this paper investigates a TTO for realizing giga-watt level high power microwaves at X-band. We adopt a three-cavity buncher and three-cavity extractor scheme for improving the energy transforming efficiency. For providing a stable high-power microwaves export, the quasi-TM 01 mode is adopted as the working mode. After optimizing the key parameters of the TTO structure and setting constant magnetic to be 0.6 T, diode voltage to be 493 KV, and the corresponding current to be 9.3 KA, the particle-in-cell (PIC) simulation results show that the output power is up to 1.88 GW at 8.14 GHz, and the corresponding energy transition efficiency is 40%.

关键词： Simulation Magnetic resonance Voltage Microwave theory and techniques Harmonic analysis Microwave oscillators Electromagnetics

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Insulating materials for realising carbon neutrality:Opportunities,remaining issues and challenges

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High Voltage 2022年第4期7卷 610-632页

作者： Chuanyang Li Yang Yang Guoqiang Xu Yao Zhou Mengshuo Jia Shaolong Zhong Yu Gao Chanyeop Park Qiang Liu Yalin Wang Shakeel Akram Xiaoliang Zeng Yi Li Fangwei Liang Bin Cui Junpeng Fang Lingling Tang Yulin Zeng Xingtao Hu Jiachen Gao Giovanni Mazzanti Jinliang He Jianxiao Wang Davide Fabiani Gilbert Teyssedre Yang Cao Feipeng Wang Yunlong Zi The State Key Laboratory of Power System Department of Electrical EngineeringTsinghua UniversityBeijingChina Department of Mechanical and Automation Engineering The Chinese University of Hong KongHong KongChina Simpson Querrey Institute Northwestern UniversityEvanstonIllinoisUSA Department of Materials Science and Engineering The Pennsylvania State UniversityUniversity ParkPennsylvaniaUSA Department of Information Technology and Electrical Engineering ETH ZürichZürichSwitzerland School of Electrical and Information Engineering Tianjin UniversityTianjinChina Department of Electrical and Computer Engineering Mississippi State UniversityMississippi StateMississippiUSA Electrical and Electronic Engineering The University of ManchesterManchesterUK Department of Electrical Engineering School of Electronic Information and Electrical EngineeringShanghai Jiao Tong UniversityShanghaiChina Key Laboratory of Control of Power Transmission and Conversion(SJTU) Ministry of EducationShanghaiChina College of Electrical Engineering Sichuan UniversityChengduChina Shenzhen Institute of Advanced Technology Chinese Academy of Sciences ShenzhenShenzhenChina School of Electrical Engineering Wuhan UniversityWuhanChina School of Integrated Circuits Tsinghua UniversityBeijingChina Jiangsu Jinxin Electric Appliance Co.Ltd. YangzhouChina Tai'an Tiancheng Safety Evaluation Co. Ltd.Tai'anChina Department Electrical Electronic and Information EngineeringUniversity of BolognaBolognaItaly National Engineering Laboratory for Big Data Analysis and Applications Peking UniversityBeijingChina Laplace Paul Sabatier Universityand CNRSToulouseFrance Electrical and Computer Engineering University of ConnecticutStorrsConnecticutUSA State Key Laboratory of Power Transmission Equipment&System Security and New Technology School of Electrical EngineeringChongqing UniversityChongqingChina Thrust of Sustainable Energy and Environment The Hong Kong University of Science and Technology(Guangzhou)GuangzhouChina De

The 2050 carbon-neutral vision spawns a novel energy structure revolution,and the construction of the future energy structure is based on equipment *** material,as the core of electrical power equipment and electrified transportation asset,faces unprecedented challenges and *** goal of carbon neutral and the urgent need for innovation in electric power equipment and electrification assets are first *** engineering challenges constrained by the insulation system in future electric power equipment/devices and electrified transportation assets are *** materials,including intelligent insulating material,high thermal conductivity insulating material,high energy storage density insulating material,extreme environment resistant insulating material,and environmental-friendly insulating material,are cat-egorised with their scientific issues,opportunities and challenges under the goal of carbon neutrality being *** the context of carbon neutrality,not only improves the understanding of the insulation problems from a macro level,that is,electrical power equipment and electrified transportation asset,but also offers opportunities,remaining issues and challenges from the insulating material *** is hoped that this paper en-visions the challenges regarding design and reliability of insulations in electrical equipment and electric vehicles in the context of policies towards carbon neutrality *** authors also hope that this paper can be helpful in future development and research of novel insulating materials,which promote the realisation of the carbon-neutral vision.

关键词： neutral insulation extreme

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