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SSRN 2023年

作者： Chen, Deqi Chen, Mingjing Liu, Hanzhou Liu, Haidong Zhong, Lei Deng, Jian Key Laboratory of Low-grade Energy Utilization Technologies and Systems Chongqing University Ministry of Education Chongqing400044 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China

This study aims to explore the dynamic distribution and hydrodynamic characteristics of droplets in the process of strong transient reflood. However, the quasi-steady state analysis is generally adopted in the current study, ignoring the dependence of droplet formation and breaking mechanism in the Dispersed flow film boiling (DFFB) mechanism on the time-related historical behaviors such as the advance of the quench front. A series of reflood cooling visualization experiments of zirconium alloy high-temperature rod-shaped heating surface were carried out to achieve this research goal. The wall surface and fluid temperature history curves were recorded, and the parameters, such as the size and velocity of DFFB regime droplets, were quantitatively extracted by visual image processing technology. Based on the formation and breakup mechanism of droplets in the dispersed flow, the reasons for droplet size distribution and velocity change with input heat flux, initial wall temperature, inlet subcooling, and inlet flow rate are well analyzed and explained. At the same time, the experimental results also show a strong correlation between droplet behavior and the reflood process in time. This study can provide more detailed physical support for the subsequent development of droplet behavior models more suitable for the strong transient reflood process and the evaluation of existing models. © 2023, The Authors. All rights reserved.

关键词： Heat flux

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Topological hinge modes in Dirac semimetals

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Frontiers of physics 2023年第1期18卷 85-95页

作者： Xu-Tao Zeng Ziyu Chen Cong Chen Bin-Bin Liu Xian-Lei Sheng Shengyuan A.Yang School of Physics Beihang UniversityBeijing 100191China Department of Physics The University of Hong KongHong KongChina Peng Huanwu Collaborative Center for Research and Education Beihang UniversityBeijing 100191China Research Laboratory for Quantum Materials Singapore University of Technology and DesignSingapore 487372Singapore Center for Quantum Transport and Thermal Energy Science School of Physics and TechnologyNanjing Normal UniversityNanjing 210023China

Dirac semimetals(DSMs)are an important class of topological states of ***,focusing on DSMs of band inversion type,we investigate their boundary modes from the effective model *** show that in order to properly capture the boundary modes,k-cubic terms must be included in the effective model,which would drive an evolution of surface degeneracy manifold from a nodal line to a nodal *** k-cubic terms are also needed for better exposing the topological hinge modes in the *** first-principles calculations,we demonstrate that this feature and the topological hinge modes can be clearly exhibited inβ-*** extend the discussion to magnetic DSMs and show that the time-reversal symmetry breaking can gap out the surface bands and hence is beneficial for the experimental detection of hinge ***,we show that magnetic DSMs serve as a parent state for realizing multiple other higher-order topological phases,including higher-order Weyl-point/nodal-line semimetals and higher-order topological insulators.

关键词： topological hinge Dirac semimetals

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design and Optimization of a Samara-Inspired Lightweight Monocopter for Extended Endurance

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IEEE Robotics and Automation Letters 2025年第7期10卷 7214-7221页

作者： Xinyu Cai Shangkun Zhong Tee Meng Tan Wei Jun Ang Shaohui Foong Engineering Product Development Pillar Singapore University of Technology and Design (SUTD) Singapore Aviation Key Laboratory of Science and Technology on Flight Control AVIC Xi'an Automatic Flight Control Research Institute Xi'an China

Small multirotors demonstrate significant potential due to their simple airframe and human-friendly operation. However, the reduced size results in substantially higher energy consumption, which severely limits their flight endurance and restricts their range of applications. Ornithopters, while offering better aerodynamic efficiency, experience energy losses due to the mechanical complexity required to generate reciprocating motion. In this work, inspired by the samara, we present a lightweight aircraft with an exceptionally simple design featuring a single actuator and a mono airfoil. To optimize the flight configuration for minimal power consumption, we employed a Surrogate optimization method that integrates spinning airfoil dynamics, motor-propeller efficiency, and hovering equilibrium. As a result, the proposed vehicle achieves position-controlled hovering flight for up to 26 minutes with a takeoff weight of only 32 grams. Its superior power efficiency is demonstrated by a high power loading of 9.1 grams per watt. Compared to state-of-the-art systems, the proposed design shows significant improvements in both flight endurance and power efficiency. The reliable and stable position-holding flight over an extended period further validates the effectiveness of the proposed methods and the practical applicability of the fabricated prototype.

关键词： Actuators Aerodynamics Automotive components Robots Propellers Torque Spinning Power demand Atmospheric modeling Payloads

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Sustainable Development of Photovoltaic Market in Zhejiang, China 1st

Sustainable Development of Photovoltaic Market in Zhejiang, ...

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1st International Conference of Urban Climate, Sustainability, and Urban design, UCSUD 2023

作者： Zhang, Gaochuan Lin, Qiaoyuan He, Bao-Jie School of Civil Engineering and Architecture Zhejiang University of Science and Technology Hangzhou310023 China Zhejiang Southeast Architectural Design Group CO. LTD Hangzhou310023 China Joint Laboratory for Urban Renewal and Future City Zhejiang310023 China School of Architecture and Urban Planning Key Laboratory of New Technology for Construction of Cities in Mountain Area Ministry of Education Chongqing University Chongqing China

ISBN: (纸本)9789819784004

Greenhouse gases, such as carbon dioxide and methane, emitted from thermal power generation, pose significant threats to human survival and development, contributing to phenomena such as floods, droughts, and storms. The photovoltaic market, as an emerging source of clean energy in China, has experienced widespread adoption and rapid growth, emerging as a cornerstone industry driving local economic development. This study focuses on the photovoltaic (PV) market in Zhejiang Province, analyzing its fundamentals across four key dimensions: market conditions, economic benefits, technological advancements, and policy frameworks. Findings demonstrate that a PV power station operating over a 30-year lifespan could potentially generate up to 864.275 billion kWh of electricity, yielding tariff revenues of 358.93 billion yuan. Moreover, such installations could significantly mitigate environmental impact by reducing carbon dioxide emissions by 873.965 billion metric tons, nitrogen oxide emissions by 245,100 metric tons, sulfur dioxide emissions by 163,900 metric tons, and conserving 261 million metric tons of standard coal. © The Author(s) 2025.

关键词： Clean energy

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Understanding Xenon and Vacancy Behaviors in Uo2, Un and U3si2: A Comparative Ab Initio Study

SSRN

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SSRN 2022年

作者： Zhao, Jiajun Sun, Dan Wang, Yuanyuan Xi, Liu Chen, Ping Zhao, Jijun Dalian University of Technology Liaoning Dalian China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Sichuan Chengdu China

Extensive attention has been paid to accident tolerant fuels (ATFs), such as uranium mononitride (UN) and uranium sesquisilicide (U3Si2), which are regarded as the potential candidates to replace uranium dioxide (UO2) in light water reactor (LWR). However, the thermodynamic behavior of fission gas atom in these fuels that can quantitatively affect the burnup characteristics of ATF needs to be explored. To this end, the systematic ab initio investigation on the energetic properties of xenon (Xe)-vacancy complexes in UO2, UN and U3Si2 is performed with the GGA+U approach as well as the corrected chemical potential. The stabilities of Xe-vacancy clusters, including interstitial trap site (IS), mono-, bi- and tri-atomic vacancy, are thoroughly assessed. The formation energies of vacancy complexes indicate that it is more likely to form vacancy cluster defects and their complexes with Xe in UO2 and to generate mono-atomic vacancy and Xe-vacancy complex in both UN and U3Si2. Xe can be strictly confined by the trap sites in UO2 and UN, and yet in U3Si2, it prefers to move to the centre of a large free volume trap site. The strongest soluble characteristic of Xe in U3Si2 indicates excellent storage compacity of fission gas products in the matrix. This work can provide comprehensive insights into the original reason of interplay between Xe and vacancy as well as the thermodynamic behavior of those defects in the uranium-based fuels. © 2022, The Authors. All rights reserved.

关键词： Uranium dioxide

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Experimental study on the sub-channel void fraction characteristics of bubbly flow in rod bundles

Experimental study on the sub-channel void fraction characte...

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

作者： Ren, Quan-Yao Pu, Zeng-Ping Zheng, Mei-Yin Su, Min Chen, Ping Pan, Liang-Ming He, Hui He, Qing-Che Science and Technology on Reactor System Design Technology Laboratory Chengdu China Chongqing China

ISBN: (纸本)9780791883785

The gas-liquid two-phase flow behaviors are always associated with its dynamic void fraction, such as flow resistance, heat transfer coefficient, phase distribution, critical heat flux etc. As regard to the commercial PWR and BWR, rod bundles are the typical geometry, which contains many subchannels for coolant flowing. In present study, the sub-channel void fraction was measured in 5×5 rod bundles with the subchannel impedance void meter consisting of 12 strip electrodes. Based on the measured void fraction in different sub-channels, the void fraction dynamics, PDF (probability distribution function) and CDF (cumulative distribution function) curves were analyzed to make clear the effect of superficial gas and liquid velocity, flow development and casing tube. The empirical correlation for PDF of dynamic sub-channel void fraction has been developed, which showed good fitness with PDF and CDF curves and satisfying accuracy of averaged void fraction. © 2020 American Society of Mechanical Engineers (ASME). All rights reserved.

关键词： Void fraction

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Summary of Effects of Oxide Layer on Permeability Coefficient of Tritium 29

Summary of Effects of Oxide Layer on Permeability Coefficien...

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2022 29th International Conference on Nuclear Engineering, ICONE 2022

作者： Zhou, Ziling Li, Wenqian Wang, Yu Guo, Jingni Wen, Yanwei Shan, Bin Xie, Feng Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy Technology Key Laboratory of Advanced Reactor Engineering and Safety Ministry of Education Tsinghua University Beijing100084 China School of Materials Science and Engineering Huazhong University of Science & Technology Wuhan430074 China

ISBN: (纸本)9780791886502

Tritium is an important nuclear fuel in fusion reactors and one of the dominant nuclides in the primary coolant in fission reactors. The storage, feeding, control, monitoring, and transport of tritium are important for practical engineering applications. Because of the high mobility of tritium in both fission and fusion nuclear systems and its effect on human body, tritium has received great attention worldwide. The retention and prevention of tritium permeation from primary loop to secondary loop is a common research interest in various reactors. Previous studies indicated that a surface oxide layer is an efficient method to reduce tritium permeation. In this paper, we summarize the effects of various oxide layers on the permeation of hydrogen isotopes in nuclear reactors. The permeation reduction factor for materials used in fusion reactors ranges from 1000 to 100000. The diffusion behavior of tritium in several materials with and without oxide layer is discussed in detail. The oxide layer is more important than intrinsic permeability to prevent tritium permeation. As tritium is the only radioactive source term in the secondary loop of high temperature gas-cooled reactors, we also reviewed the permeation of hydrogen isotopes in the heat exchanger, which is an important issue in nuclear hydrogen production. The present study provides a comprehensive overview of tritium permeation behavior and is expected to promote the development and design of tritium-permeation-proof materials in the future. © 2022 by ASME.

关键词： Tritium

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Thinning air-water films stabilized by bacterial particles

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Acta Mechanica Sinica 2021年第1期37卷 27-34,I0001页

作者： Song Wu Yuehua Yang Hongyuan Jiang Hefei National Laboratory for Physical Science at the Microscale CAS Key Laboratory of Mechanical Behavior and Design of MaterialsDepartment of Modern MechanicsCAS Center for Excellence in Complex System MechanicsUniversity of Science and Technology of ChinaHefei230026China

The ability of particles to stabilize liquid films has broad applications in many fields,such as drug delivery,biofuel catalysis,and crude-oil *** mechanism of particles to stabilize emulsions has been widely ***,how particles affect the stability of suspension films is still ***,the dynamics of bacterial particles on free liquid films during evaporation is obtained by direct microscopic *** find that the initial concentration of the bacterial solution affects the evolution of the shapes and stabilities of liquid *** liquid film with a low bacterial concentration exhibits a drainage and rupture process similar to pure water,and bacteria would be evacuated during the evaporation of liquid ***,when the bacterial concentration is high,bacteria form a single-layer array in the center of the film and greatly enhance the stability of the liquid *** demonstrate that these two distinct film evaporation dynamics are caused by the difference in the lateral capillary force of the particles at different positions on the liquid film,which is not affected by the active motility of ***,our research reveals the critical role of bacteria concentration in stabilizing suspension liquid film.

关键词： Bacterial concentration Evaporation dynamics Film stability Lateral capillary force

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Neural Oscillation-dependent Electroencephalographic Microstates Reveal Emotional Process-specific Dynamic Neuromarkers of Depression

Neural Oscillation-dependent Electroencephalographic Microst...

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2024 IEEE International Conference on Bioinformatics and Biomedicine, BIBM 2024

作者： Cui, Kunbo Zhao, Mingqi Wu, Zhongqing Zhang, Lixin Jiang, Hua Zhao, Qinglin Hu, Bin Lanzhou University School of Information Science and Engineering Lanzhou China Lanzhou University Key Laboratory of Special Functional Materials and Structural Design Ministry of Education Lanzhou China Beijing Institute of Technology School of Medical Technolog Beijing China

ISBN: (纸本)9798350386226

Depressive affective dysfunction could be manifested by dynamic reorganization processes of functional brain networks under emotional tasks. However, such emotional task-specific reorganizations remain not fully understood in terms of spatiotemporal organization of oscillation dynamics. The insufficiency of approaches for quantifying such dynamic reorganization limits the effective extraction of dynamic neuromarkers of depressive affective dysfunction. To address this gap, this study presents a neural oscillation-dependent microstate approach to quantify the dynamic reorganization process of functional networks at high temporal resolution. The approach was tested by analyzing a 64-channel electroencephalography (EEG) dataset with 110 participants (55 depressed patients and 55 normal controls) collected during emotional tasks with four affective polarities (positive, neutral, negative, and resting state). Our analyses revealed oscillation-dependent microstates that reflected abnormalities in the networks associated with external information processing and interoception in depression. Our analyses further suggest that such abnormalities may be caused by dysfunction in a limited number of brain regions, which then dynamically affects functional brain networks. These findings may reflect increased self-focus and deficits in the perception of external information in depression. In summary, our study further explores source-level evidence related to abnormalities in microstate features of depression based on the generalization of depression microstate research to a multi-band framework. Our study provides a direction for expanding the application of dynamic reorganization analyses of functional networks with high temporal resolution, and provides new support and insights into the neural mechanisms of affective dysfunction in depression. © 2024 IEEE.

关键词： Electroencephalography

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Load Calculation of Cylinder Moving in Waves 34th

Load Calculation of Cylinder Moving in Waves

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34th International Ocean and Polar Engineering Conference, ISOPE 2024

作者： Li, Jing Wang, Junyi Wang, Xianzhou Wang, Qing School of Naval Architecture and Ocean Engineering Huazhong University of Science and Technology China Key Laboratory of ship and ocean hydrodynamics of Hubei Province Hubei Wuhan China Wuhan Second Ship Design and Research Institute Hubei Wuhan China

ISBN: (纸本)9781880653784

In order to investigate the wave load of cylinder such as masts on submarines, this study compares numerical simulations of cylinder under different submerged depths and speeds in irregular wave and calm water. Before the study, validation of the numerical method was conducted for time-steps/grid independent studies and uncertainty analysis of the numerical simulation results includes evaluation of significant wave height. Then, the numerical loads in wave conditions are compared with those in calm waters, and the numerical wave results are also compared with those calculated by Morison formula. Finally, the discipline of wave load under different conditions and the ratios of numerical results to Morison formula results are concluded. © 2024 by the International Society of Offshore and Polar Engineers (ISOPE).

关键词： Uncertainty analysis

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