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Sustainable Power and Energy Conference (iSPEC)

作者： Jinxin Wang Peng Renyong Kailei Dai Zhiqiang Zhang Ting Zhang Junjie Zhao Qian Chen Jianjian Zhang Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China Nuclear Power Institute of China Chengdu China

ISBN: (数字)9781728191645

ISBN: (纸本)9781728191652

The integrated charging system of Electric vehicle consists of a single-phase PWM rectifier and a Buck converter. When the single-phase PWM rectifier works with unit power factor, the dc-link voltage contains a large voltage harmonic of twice the grid frequency. Although the output voltage ripple can be controlled within the required range using the proper control of the Buck converter, the second-order harmonic on the dc-link capacitor is inevitable. This paper proposes a de-side decoupling method for the second-order harmonic problem of the dc-link voltage of the integrated charging system. A de-side decoupling half bridge is connected in parallel to absorb the ripple power of twice the grid frequency. This paper analyzes the operating principle of the de-side decoupling half bridge. Based on a theoretical analysis of the topology and the design procedure for controlling system, the proposed converter is designed and simulated. Finally, simulation results are given to verify the method.

关键词： Capacitors Rectifiers Bridge circuits Pulse width modulation Harmonic analysis Control systems Voltage control

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Anomalous Polarization-Switching Phenomena and Noteworthy Pyroelectricity in Ferroelectric Hf0.5zr0.5o2 Polycrystalline Films

SSRN

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SSRN 2023年

作者： Wang, Xudong Zhou, Yong Xiong, Ke Wu, Shuyu Tu, Luqi Chen, Yan Wu, Shuaiqin Zeng, Jinhua Zheng, Yuqing Gu, Shiqun Luo, Man Lin, Tie Shen, Hong Meng, Xiangjian Liu, Qi Chu, Junhao Wang, Jianlu State Key Laboratory of Infrared Physics Shanghai Institute of Technical Physics Chinese Academy of Sciences Shanghai200083 China Key Laboratory of Microelectronics Device and Integrated Technology Institute of Microelectronics Chinese Academy of Sciences Beijing100029 China Frontier Institute of Chip and System Fudan University Shanghai200433 China Shanghai Frontier Base of Intelligent Optoelectronics and Perception Institute of Optoelectronics Fudan University Shanghai200433 China Hangzhou Institute for Advanced Study University of Chinese Academy of Sciences Chinese Academy of Sciences Hangzhou330106 China BirenTech Shanghai201114 China Jiangsu Key Laboratory of ASIC Design School of Information Science and Technology Nantong University Jiangsu Nantong226019 China

Hafnia-based oxide thin films exhibit unconventional robust ferroelectricity at the nanoscale, paving the way for advancements in next-generation nanoelectronics. However, the stability and dynamics of ferroelectric polarization in hafnia-based oxides films, particularly at the nanoscale, warrant further exploration. In this study, we delve into the factors influencing the formation of the ferroelectric phase. Our findings illuminate that the confinement effect of the capped layer enhances the stabilization of the metastable orthorhombic phase, thereby bolstering its ferroelectricity and endurance. Furthermore, we identify an unprecedented polarization-switching behavior in HfO2-based ferroelectric films, characterized by a decrease in the remanent polarization and an increase in the coercive field as the temperature drops. This peculiar phenomenon can be ascribed to the reduction in the long-range interaction of polarization dipoles upon cooling, as evidenced by the dielectric spectrum. The diminished long-range interaction results in the emergence of nanodomains and a re-entrant relaxer behavior, offering novel insights into the origin of ferroelectricity and the stability of ferroelectric polarization in hafnia-based thin films. Given the commendable compatibility of Hf0.5Zr0.5O2 films with Si substrates and a pyroelectric coefficient of -62.1 μC/m2·K, they emerge as a prime candidate for sensor device applications. © 2023, The Authors. All rights reserved.

关键词： Thin films

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A review and correlations for two phase flow heat transfer in helically coiled tubes 27

A review and correlations for two phase flow heat transfer i...

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

作者： Ma, Haifu Xu, Tao Li, Peiying Gou, Junli Yuan, Hongsheng Chen, Wei Wu, Yirui Zhong, Mingjun Gao, Yingxian Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China School of Nuclear Science and Technology Xi'an Jiaotong University Xi'an710049 China

ISBN: (纸本)9784888983051

Helically coiled heat exchangers have been widely applied in many power conversion systems for their advantages, such as compactness and high efficiency in heat transfer. Reliable heat transfer models are required to analyze the thermal hydraulic characteristics of the once-through helically coiled tube steam generator. The purpose of this study is to evaluate the applicability of the existing heat transfer models. This paper review the experiments for heat transfer in helically coiled tubes in the case of two-phase flow, and summarize and screening corresponding experimental data and correlation. Then, this article compared these correlations to the existing available experimental data to evaluate the applicability of these correlations. Most of the correlations for two phase heat transfer were also valid within the parameter range of pressure, mass flux and heat flux. Results indicate that the currently existing correlation could not accurately match the experiment date. And the Steiner-Taborek correlation was recommended even though the 70% experiment date within the 20% deviation of predicted. Therefore the steam-water two phase flow need to further study to conclude a more suitable correlation in the further. Copyright © 2018-2019 by JSME

关键词： Two phase flow

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Effect of variable stroke on combustion characteristics and stability of a free-piston engine generator

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Applied Thermal Engineering 2025年 277卷

作者： Chang Liu Boru Jia Zhen Liu Zhiyuan Zhang Xiaoxu Hu Shuojian Wei Yuguo Ma School of Mechanical Engineering Beijing Institute of Technology Beijing 100081 China Hubei Key Laboratory of Power System Design and Test for Electrical Vehicle Hubei University of Arts and Science Xiangyang 441053 China

The free-piston engine generator (FPEG) features a variable stroke structure, offering significant advantages in multi-fuel adaptability and high-efficiency combustion technologies. Stroke control and design directly affect combustion regulation and system performance, and thus represent a key challenge in FPEG development. Existing studies on stroke variation mostly rely on numerical simulations, often neglecting fuel short-circuit losses and lacking experimental validation of actual combustion performance and stability. In this study, an experimental approach was employed to investigate the effects of stroke length variation (47–55 mm) on the combustion characteristics, system performance, and operational stability of an FPEG. The results show that shortening the stroke reduced the indicated work by 4.3 % from 55 mm to 47 mm, but increased the operating frequency by 14.7 %, resulting in a 10 % improvement in indicated power. Moreover, shorter stroke lengths enhanced both indicated thermal efficiency and fuel economy, with the indicated thermal efficiency increasing by 19.6 % and the minimum ISFC reaching 336 g/(kW·h). In terms of stability, the short-stroke configuration markedly reduced cycle-to-cycle variations in both combustion and system operation: COV Pmax and COV IMEP decreased by 34.5 % and 50.6 %, respectively, while COV f dropped to 0.59 %.This study is the first to experimentally reveal the influence of stroke variation on FPEG performance, providing valuable data support for structural optimization and performance control of FPEG systems.

关键词： Combustion characteristics Engine performance Free-piston engine generator Stability Variable stroke

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The SIF model of Zr-4 cladding tube with axial cracks 14

The SIF model of Zr-4 cladding tube with axial cracks

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14th International Nuclear Fuel Cycle Conference, GLOBAL 2019 and Light Water reactor Fuel Performance Conference, TOP FUEL 2019

作者： Chen, L. Liu, L.L. Song, X.M. Pang, H. Xie, X.M. Zeng, X.G. Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China No.328 1st Section of Changshun Avenue Chengdu610213 China Sichuan University No.24 1st South Section of 1st Ring Road Chengdu610021 610213 China

The calculation of the stress intensity factor (SIF) on the axial cracking of the cladding tube is the basis for the study of the failure phenomena of delayed hydride cracking (DHC) and hydrogen embrittlement (HE). In most hydrogen failure models, especially the DHC model, an infinite or semi-infinite plate is used as the modeling basis. There is no doubt that cylindrical shell as a modeling object will make the calculation more accurate for nuclear fuel cladding. This work analyzes the influence of geometric conditions and the external load conditions on SIF of tubular components, respectively, based on virtual crack closure technique (VCCT), using single variable. Then the influence of crack length on SIF is analyzed under concentrated stress loading on the end of Zr-4 cladding tube by numerical analysis method. The approximate calculation formula of the stress intensity factor on the crack front is obtained and verified. Copyright © GLOBAL 2019 - International Nuclear Fuel Cycle Conference and TOP FUEL 2019 - Light Water reactor Fuel Performance *** rights reserved.

关键词： Stress analysis

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Estimation of Anthropogenic Heat from Buildings Based on Various Data Sources in Singapore

SSRN

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SSRN 2022年

作者： He, Wenhui Li, Xian-Xiang Zhang, Xiaohu Yin, Tiangang Norford, Leslie K. Yuan, Chao School of Atmospheric Sciences Key Laboratory of Tropical Atmosphere-Ocean System Ministry of Education Sun Yat-sen University Guangdong Zhuhai China Southern Marine Science and Engineering Guangdong Laboratory Zhuhai China Department of Urban Planning and Design The University of Hong Kong Hong Kong Earth System Science Interdisciplinary Center University of Maryland College ParkMD United States Department of Architecture Massachusetts Institute of Technology CambridgeMA United States Center for Environmental Sensing and Modeling Singapore-MIT Alliance for Research and Technology Singapore Department of Architecture National University of Singapore Singapore

Heat released from the energy consumption in buildings (QB) is an important component of anthropogenic heat, which is a major contribution to the urban heat island (UHI) phenomenon. However, it is still a challenge to integrate all the available data to improve the estimation of QB due to inconsistence among multiple data sources. This paper presents a solution to estimate the anthropogenic heat from buildings in Singapore by classifying the buildings into the electricity consumption sectors based on random forest classification model using multiple data sources. The classification model achieves a cross validation accuracy score of 95% by using building use type, land use type of land parcel where the building stands, location and area as predictors. Based on the classification result, the daily average QB from the commercial buildings (CS), Housing and Development Board (HDB) apartments, private apartments and condominiums (AC), and landed properties (LP) were estimated to be 12.1, 4.4, 3.2 and 1.1 W m-2 on a 200 m-by-200 m grid, respectively. QB was approximately 9% of the net all-wave radiation in Singapore in 2015. Our approach can serve as a useful tool for integrating dataset from different sources with inconsistent categorisations. © 2022, The Authors. All rights reserved.

关键词： Energy utilization

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Flexible, Multi-Shank Stacked Array for High-Density Omini-Directional Intracortical Recording

Flexible, Multi-Shank Stacked Array for High-Density Omini-D...

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IEEE International Conference on Micro Electro Mechanical systems

作者： Zhejun Guo Longchun Wang Bowen Ji Ye Xi Bin Yang Jingquan Liu National Key Laboratory of Science and Technology on Micro/Nano Fabrication Shanghai Jiao Tong University China Unmanned System Research Institute Northwestern Polytechnical University Xi'an China

ISBN: (数字)9781665419123

ISBN: (纸本)9781665430241

This paper presents a flexible multi-shanks omini-directional neural probe array. The flexible probe includes eight shanks with different length, each shank contains 128 recording sites. Traditional Multilayer lithography is applied to fabricate the probe and a novel stacked structure is design with four-sided electrodes (32 sites on surface and 96 sites on sidewall) is proposed in this multi-shank array, which increases the electrode density of integration and the stacked structure can be readily scaled up to 1024 channels. It has been proved that the impedance at 1 kHz of the electrodes on the surface and the sidewalls are 830 kΩ and 1.1 MΩ in vitro respectively. With such design, longer life span can be achieved and the probe can capture richer neural signal. In addition, a method of microwire assisted implantation is proposed to ensure successful implantation in agar model.

关键词： Electrodes Micromechanical devices Surface impedance Reliability Impedance Probes In vitro

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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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Accelerating catalysts design by machine learning

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science Bulletin 2020年第19期65卷 1593-1594页

作者： Haishan Yu Jun Jiang Hefei National Laboratory for Physical Sciences at the Microscale CAS Key Laboratory of Mechanical Behavior and Design of MaterialsSchool of Chemistry and Materials ScienceUniversity of Science and Technology of ChinaHefei 230026China

The climate crisis associated with rapid accumulation of carbon dioxide in atmosphere has posed increasing threat to human wellbeings[1].It is of great significance to capture and convert CO2 to realize sustainable utilization of carbon resources[1].The electrocatalytic CO2 reduction reaction(CO2RR)provides a sustainable,carbon-neutral method for solving this *** the difficulty of finding an efficient catalysts slows down the realization of the ambitious *** is mainly because it requires simultaneous optimization of selectivity for a specific product,energy conversion efficiency,current density and stability of the reaction system.

关键词： realization dioxide neutral

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Ray-Tracking Simulation and Analysis of Propagation for Typical Scene of High Speed Maglev

Ray-Tracking Simulation and Analysis of Propagation for Typi...

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International Conference on Communication technology (ICCT)

作者： Chen Kewei Liu Hongbo Liang Jiaqi Liu Qintao College of Electronic Engineering Naval University of Engineering Wuhan China National Key Laboratory of Science and Technology on Vessel Integrated Power System Naval University of Engineering Wuhan China

ISBN: (纸本)9781665432078

The propagation of 38 GHz and 3.5 GHz in typical scenarios of high-speed maglev train is studied. Referring to the magnetic field configuration of Shanghai Maglev, the viaduct and tunnel scenes are modeled and simulated. The propagation characteristics at 38GHz and 3.5GHz are compared in terms of receiving power and Doppler frequency shift, and the broadband path loss and delay spectrum parameters are modeled, which provides suggestions for the design of high-speed data transmission communication system.

关键词： Reflectivity Doppler shift Magnetic levitation vehicles Scattering Propagation losses Data models Magnetic analysis

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