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

作者： Huijian, Huang Peng, Wang Dongyang, Li Tan, Sichao Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China Fundamental Science on Nuclear Safety and Simulation Technology Laboratory Harbin Engineering University Harbin Heilongjiang China

ISBN: (纸本)9780791883785

In the nuclear field, the reactor using plate fuel assembly forms multiple jets at exit. So, it's meaningful to study multiple jets to learn the behavior of the coolant when it leaves the core. This paper uses PIV technology to study the flow characteristics of 9 jets at low Reynolds number. Firstly, the velocity field reveals that the pressure outside the jet is greater than the inside of the jet, which causes the jet to deflect and converge inward at z/w=0-8. Then, the velocity field with different Re number is analyzed in the center plane, and find that the flow distribution is similar. Then, a detailed analysis is performed on the jet under specific conditions, and the merge point is discussed in the paper. At the same time, the first-order velocity tensor are also calculated in this paper. In addition, this article also analyzes the jet flow field after the central narrow channel was blocked. In this experiment, a plug was used to block the No. 5 jet by 1/3. And the flow redistribution is discussed in this case. The methods of flow calculation using PIV technology is established and compared with the real number of flowmeters, it's found that the calculation method is rather accurate. On the other hand, the experiment find that the distribution of flow in each channel is not uniform, and the blocking condition make an increase in the flow of edge channels, which leads to the decreasing of flow in the blocked adjacent channel. © 2020 American Society of Mechanical Engineers (ASME). All rights reserved.

关键词： Velocity

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Study on natural circulation flow instabilities in rod bundle channel under rolling condition

Study on natural circulation flow instabilities in rod bundl...

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

作者： Cheng, Kun Deng, Jian Cai, Rong Qian, Libo Qi, Peiyao Ke, Bingzheng Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Fundamental Science on Nuclear Safety and Simulation Technology Laboratory Harbin Engineering University Heilongjiang150001 China

ISBN: (纸本)9780791883785

The effects of rolling condition on the flow instability characteristics of natural circulation (NC) in rod bundle channel were experimentally studied. A 3×3 rod bundle channel is used as the testing section. The experimental system pressure range is 0.2 to 0.6 MPa, and the range of inlet subcooling is 10 to 70°C. The ranges of rolling motion amplitude and period are 10 ∼ 20° and 10 ∼ 30s, respectively. Two typical two-phase flow instabilities in rod bundle channel under rolling condition were found in experiments: (a) the trough-type oscillation caused by the vapor generation at the minimum point of flow fluctuation and (b) the compound oscillation formed by the superposition of the trough-type oscillation and DWOI. Experimental results show that the rolling motion can reduce the threshold heating power of trough-type oscillation and cause the occurrence of NC flow instability in advance. But the rolling motion cannot affect the dimensionless boundary of DWOI in rod bundle channel. © 2020 American Society of Mechanical Engineers (ASME). All rights reserved.

关键词： Two phase flow

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Α-Moc@Cs Carrier Modulated Platinum Single Atoms to Enhance Catalytic Activity in Solar Cells

SSRN

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SSRN 2022年

作者： Yao, Jixin Wang, Jie Wang, Wen Meng, Ying Wang, Haibo Lu, Shibin Du, Feng Yang, Li Zuo, Xueqin Li, Guang Anhui Province Key Laboratory of Simulation and Design for Electronic Information System Universitie s Joint Key Laboratory of Photoelectric Detection Science and Technology Hefei Normal University Anhui Province Hefei230601 China School of Materials Science and Engineering Anhui Key Laboratory of Information Materials and Devices Key Laboratory of Structure and Functional Regulation of Hybrid Materials Ministry of Education Institute of Physical Science and Information Technology Anhui University Hefei230601 China Institute of Materials Science and Devices School of Materials Science and Engineering Suzhou China University of Science and Technology Suzhou215011 China

Single-atom electrocatalysts have been proven to be the great promising catalysts for energy-related fields yet their active site structure remains elusive, especially in dye-sensitized solar cell (DSSC). Herein, atomically dispersed Pt is confined into α-MoC@CS carrier (Pt/α-MoC@CS), which vigorously stimulates the activity of Pt single atoms under strong interactions. As expected, the Pt/α-MoC@CS as the cathode in DSSC exhibits high power conversion efficiency (PCE) of 9.87%, exceeding Pt electrode (7.61%). X-ray photoelectron spectroscopy combined with density functional theory calculations reveals that the high activity is mainly derived from charge re-distribution of Pt/α-MoC@CS caused by the interaction between Pt atoms and α-MoC. This interaction not only achieves the optimized adsorption/desorption energy of reactants but also brings synergic advantages to expedite the reaction kinetics of the overall system. This work paves further research prospects for charge re-distribution, stimulating electrocatalysts to effectively enhance their catalytic properties by an atomic-level engineering strategy. © 2022, The Authors. All rights reserved.

关键词： Cathodes

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BREAKING THE DEGREES-OF-FREEDOM LIMIT OF HOLOGRAPHIC MIMO COMMUNICATIONS: A 3-D ANTENNA ARRAY TOPOLOGY

arXiv

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arXiv 2023年

作者： Yuan, Shuai S.A. Wu, Jie Xu, Hongjing Wang, Tengjiao Li, Da Chen, Xiaoming Huang, Chongwen Sun, Sheng Zheng, Shilie Zhang, Xianmin Li, Er-Ping Sha, Wei E.I. College of Information Science and Electronic Engineering Zhejiang University Hangzhou310027 China Anhui Province Key Laboratory of Simulation and Design for Electronic Information System Hefei Normal University Hefei230601 China Wireless Network Research Department Huawei Technologies Shanghai201206 China School of Information and Communications Engineering Xi’an Jiaotong University Xi’an710049 China School of Electronic Science and Engineering University of Electronic Science and Technology of China Chengdu611731 China

The performance of holographic multiple-input multiple-output (MIMO) communications, employing two-dimensional (2-D) planar antenna arrays, is typically compromised by finite degrees-of-freedom (DOF) stemming from limited array size. The DOF constraint becomes significant when the element spacing approaches approximately half a wavelength, thereby restricting the overall performance of MIMO systems. To break this inherent limitation, we propose a novel three-dimensional (3-D) antenna array that strategically explores the untapped vertical dimension. We investigate the performance of MIMO systems utilizing 3-D arrays across different multi-path scenarios, encompassing Rayleigh channels with varying angular spreads and the 3rd generation partnership project (3GPP) channels. We subsequently showcase the advantages of these 3-D arrays over their 2-D counterparts with the same aperture sizes. As a proof of concept, a practical dipole-based 3-D array, facilitated by an electromagnetic band-gap (EBG) reflecting surface, is conceived, constructed, and evaluated. The experimental results align closely with full-wave simulations, and channel simulations substantiate that the DOF and capacity constraints of traditional holographic MIMO systems can be surpassed by adopting such a 3-D array configuration. © 2023, CC BY-NC-ND.

关键词： Energy gap

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Flexible data handling in the flight control decision software for space science satellites 15th

Flexible data handling in the flight control decision softwa...

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15th International Conference on Space Operations, SpaceOps 2018

作者： Zhang, Y.Z. Peng, X.D. Gao, C. Laboratory of System Simulation and Concurrent Design Technology National Space Science Center Chinese Academy of Sciences Beijing100190 China Laboratory of System Simulation and Concurrent Design Technology University of Chinese Academy of Sciences Beijing100049 China

ISBN: (纸本)9781624105623

In order to support the in-orbit operation of the satellites in the Strategic Priority Program on Space Science, the Flight Control Decision Support Software (FCDSS) is developed. It belongs to the mission operation subsystem of the ground support system of the Strategic Priority Program on Space Science. The FCDSS is responsible for the comprehensive analysis of the operating status of the onboard equipment, the use of the satellite resources, the scientific detection results, and full life cycle visualization of the scientific mission in real time and afterwards, and mission situation analysis. The software contains two parts--"Flight Control Decision Analysis and Comprehensive Situation Visualization Unit" and "Full-lifecycle Data Processing Unit". The latter is the main focus in this paper. It is responsible for acquiring required data (such as telemetry data) from the database and do calculations for coverage analysis, observation plan analysis and etc. Due to the various types and massive amount of data need to be processed, it posed high requirements to data processing. In brief, in this paper, we will first describe the software architecture in detail. Then, give detailed information on the design and implementation of the data processing layer. At last, mission applications of the software will be shown with conclusions on the performance and lessons we have learned as the four mission carries on. © 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Visualization

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The friction characteristics and velocity distribution of pulsatile flows in a rod bundle 27

The friction characteristics and velocity distribution of pu...

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27th International Conference on Nuclear Engineering: Nuclear Power Saves the World!, ICONE 2019

作者： Li, Xing Qi, Peiyao Tan, Sichao Mi, Zhengpeng Li, Dongyang Fundamental Science on Nuclear Safety and Simulation Technology Laboratory Harbin Engineering University Harbin Heilongjiang China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

ISBN: (纸本)9784888983051

The transient fluctuation of flow rate in a nuclear reactor is a common phenomenon in floating reactors and possible accident scenarios, the response for transient flow determined the damage threshold of fuel assemblies. Friction characteristics and velocity distribution of low-frequency pulsatile flows in a rod bundle have been studied. The experiments were conducted under the time-averaged Reynolds number 1000 Copyright © 2018-2019 by JSME

关键词： Pressure drop

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An acceleration technique for method of characteristics based on preconditioning method and CUDA technique 27

An acceleration technique for method of characteristics base...

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27th International Conference on Nuclear Engineering: Nuclear Power Saves the World!, ICONE 2019

作者： Zheng, Yong Peng, Minjun Ping, A.N. Wei, L.U. Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu Sichuan China Fundamental Science on Nuclear Safety and Simulation Technology Laboratory Harbin Engineering University Harbin Heilongjiang China

ISBN: (纸本)9784888983051

The method of characteristics (MOC) with matrix form has more favorable performance compared with its standard application. And the linear algebraic solver affects heavily the computation efficiency. As a Krylov subspace technique, the preconditioned generalized minimal residual algorithm (PGMRES) was proposed to solve the resulting linear system in previous work. To accelerate the iteration process further, the current study utilizes the GPU-based compute unified device architecture(CUDA) technique to program the massively parallel PGMRES. The sparse matrix vector multiplication(SpMV), the most time-consuming operation, was optimized using the coherent visiting and shared memory, which improves the parallel computing performance significantly. Based on the analysis of the numerical feature of the coefficient matrix, two parallel optimization strategies are proposed to deal with the first part of the matrix equation, and the different schemes are utilized to the different parts of the matrix based on the size of row vector, which are expected to improve the throughput of the SpMV operation. The benchmark problem HTTR(i.e. 2D high temperature engineering test reactor benchmark problem) has been simulated to verify the parallel code and evaluate the acceleration performance, and the numerical results demonstrate that the parallel strategies are efficient for the HTTR problem, and the speedup can achieve more than 5.5 times with the optimal strategy. © 2018-2019 by JSME

关键词： Linear systems

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Dual-Regulation of Α-Moc Quantum Dots and Mo-N-C Sites to Achieve High Photoelectric Conversion Performance in Solar Cell

SSRN

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SSRN 2022年

作者： Yao, Jixin Wang, Wen Wang, Jie Meng, Ying Lu, Shibin Tong, Xiaowei Du, Feng Yang, Li Xu, Haifeng Yang, Bo Tang, Huaibao Li, Guang Anhui Province Key Laboratory of simulation and design for Electronic information system Universities Joint Key Laboratory of photoelectric detection Science and Technology in Anhui Province Hefei Normal University Hefei230601 China School of Materials Science and Engineering Anhui Key Laboratory of Information Materials and Devices Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education Institute of Physical Science and Information Technology Anhui University Hefei230601 China Institute of Materials Science and Devices School of Materials Science and Engineering Suzhou University of Science and Technology Suzhou215011 China School of Information Engineering Suzhou University Suzhou234000 China School of Physics and Electronic Information Huaibei Normal University Huaibei235000 China

Constructing low-price yet high-efficiency counter electrode (CE) materials for dye-sensitized solar cells (DSSCs) is vital in energy conversion fields. Herein, α-MoC quantum dots (QD) decorated with Mo-N-C site is encapsulated in a unique carbon flower structure (α-MoCQD@NCF) as efficient CE. The α-MoCQD@NCF CE in DSSC exhibits high power conversion efficiency (PCE) with up to 9.12%, which greatly exceeds the pure Pt (7.53%). The electron microscope reveals that α-MoCQD@NCF is an ultrathin-hierarchical hollow structure, which facilitates the adequate contact of the electrolyte. Simultaneously, the ultra-small size of QD is advantageous for maximizing the utilization of active sites to accelerate the tri-iodide reduction reaction. Additionally, theory calculations indicate that atomic engineering Mo-N-C sites coupled with α-MoC quantum dots can complement and reinforce each other to transfer electrons to the carbon matrix. This electronic modulation synergistically accelerates the electron transport on the surface of CE, restraining iodide ion coupling and optimizing reaction kinetics. © 2022, The Authors. All rights reserved.

关键词： Nanocrystals

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Dual Electrical-Behavior Regulation of Α-Moc Quantum Dots and Mo-N-C Sites for High Photoelectric Conversion Performance of Solar Cells

SSRN

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SSRN 2022年

作者： Yao, Jixin Wang, Wen Wang, Jie Meng, Ying Lu, Shibin Wang, Haibo Du, Feng Yang, Li Yang, Bo Tang, Huaibao Xu, Haifeng Li, Guang Anhui Province Key Laboratory of Simulation and Design for Electronic Information System Universities Joint Key Laboratory of Photoelectric Detection Science and Technology in Anhui Province Hefei Normal University Hefei230601 China School of Materials Science and Engineering Anhui Key Laboratory of Information Materials and Devices Key Laboratory of Structure and Functional Regulation of Hybrid Materials Ministry of Education Institute of Physical Science and Information Technology Anhui University Hefei230601 China Institute of Materials Science and Devices School of Materials Science and Engineering Suzhou University of Science and Technology Suzhou215011 China School of Information Engineering Suzhou University Suzhou234000 China School of Physics and Electronic Information Huaibei Normal University Huaibei235000 China

Constructing low-price yet high-efficiency counter electrode (CE) materials for dye-sensitized solar cells (DSSCs) is vital in the field of energy conversion. Herein, α-MoC quantum dots (QDs) decorated with Mo-N-C sites are encapsulated in a unique carbon flower structure (α-MoCQD@NCF) as efficient CE. The α-MoCQD@NCF CE in DSSC exhibits high power conversion efficiency (PCE) with up to 9.12%, which greatly exceeds that of pure Pt (7.53%). Electron microscopy reveals that α-MoCQD@NCF is an ultrathin-hierarchical hollow structure, which facilitates the adequate contact of the electrolyte. Simultaneously, the ultra-small size of the QDs is advantageous for maximizing the utilization of active sites to accelerate the triiodide reduction reaction. Additionally, theoretical calculations indicate that atomically engineered Mo-N-C sites combined with α-MoC quantum dots can complement and reinforce each other to transfer electrons to the carbon matrix. Therefore, through the synergistic effect of the dual regulation of electron transfer rate and pathway by the two structures, the electron transfer on the CE surface is accelerated, the iodide ion coupling is suppressed and the reaction kinetics are optimized. It not only offers a rational approach to develop low-cost yet highly active electrode material, but also opens an avenue for other energy-related fields. © 2022, The Authors. All rights reserved.

关键词： Electrocatalysis

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Stability and energetics of two-dimensional surface crystals in liquid AuSi thin films and nanoscale droplets

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Physical Review Materials 2021年第7期5卷 074003-074003页

作者： Hailong Wang Mengyuan Wang Alireza Shahabi Alain Karma Moneesh Upmanyu CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics CAS Center for Excellence in Complex System Mechanics University of Science and Technology of China Hefei Anhui 230027 China Group for Simulation and Theory of Atomic-Scale Material Phenomena (stAMP) Department of Mechanical and Industrial Engineering Northeastern University Boston Massachusetts 02115 USA Department of Physics Northeastern University Boston Massachusetts 02115 USA

We employ atomic-scale computational frameworks to study the surface crystallization in AuSi films and droplets as a function of composition, temperature, and size. Above the melting point, the surfaces of both thin films and droplets undergo a first-order transition from a two-dimensional (2D) Au2Si crystalline phase to a laterally disordered yet stratified layer. The thin film surfaces exhibit an effective surface tension that increases with temperature and decreases with Si concentration, while for droplets in the size range 10–30 nm, the bulk Laplace pressure alters the surface segregation as it occurs with respect to a strained bulk. Above the transition, the size effect on the surface tension due to the stratified surface layer is small, while the crystalline surface layer below the transition is strained and composed of 2D crystallites separated by extended grain boundary scars that lead to large fluctuations in its energetics. As a specific application, all-atom simulations of AuSi droplets on Si(111) substrate subject to Si surface flux show that the supersaturation dependent surface tension destabilizes the contact line via formation of a precursor wetting film on the solid-vapor interface and has ramifications for size selection during droplet-catalyzed routes for nanowire growth. Our study sheds light on the interplay between stability and energetics of surfaces in this unique class of binary alloys and offers pathways for exploiting their surface structure for varied applications such as catalytic nanocrystal growth, dealloying, and polymer crystallization.

关键词： Crystal forms Growth Interface & surface thermodynamics Nanocrystals Structural phase transition 2-dimensional systems Surfaces Molecular dynamics

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