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Analysis for magnetic field disturbance of modular multilevel converter based high voltage direct current(MMC-HVDC)converter valve

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High Voltage 2023年第1期8卷 91-101页

作者： Lei Qi Muxue Wang xiangyu zhang Hong Shen Hongyu Wang Chongqing Jiao State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijingChina

The standardised design and operational reliability enhancement of the flexible DC converter valve are impending with the construction of high shares of renewables and power electronics power system.A power frequency magnetic field calculation model able to obtain the electromagnetic disturbance at the submodule(SM)drive board during normal operation of a flexible DC converter valve is *** of SMs with complex structures in a converter valve tower are simplified by the equivalent to the line current to fulfil calculation accuracy *** addition,a random function is employed to simulate the non-sequential switching process of the *** comparing the calculated results with the measured data obtained from the SM equivalent operation experiment of 2200 V/2150 A,the validity of the calculation model is *** to the final calculations,the influence of non-sequential switching cannot be ignored when recognising the time-domain distribution features of the power frequency magnetic field of the drive ***,engineering design can be guided only by the power frequency magnetic field intensity of the drive board calculated based on SM’s full removal in the valve tower.

关键词： disturbance converter magnetic

Preparation of Poly(ε-caprolactone)/Poly(ester amide)Electrospun Membranes for Vascular Repair

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Chemical Research in Chinese Universities 2022年第4期38卷 1111-1117页

作者： zhang xiangyu BAI Shan ZANG Leilei CHEN Xiaoqi YUAN Xiaoyan School of Materials Science and Engineering Tianjin Key Laboratory of Composite and Functional MaterialsTianjin UniversityTianjin300350P.R.China Institute of Energy Resources Hebei Academy of SciencesShijiazhuang050081P.R.China

With adjustable amphiphilicity and anionic/cationic charge,biodegradability and biocompatibility,amino acid-based poly(ester amide)s(PEAs)have drawn attention in the research of tissue engineered vascular *** this work,L-phenylalanine-based PEAs with or without L-lysine were synthesized through polycondensation,and ultrafine fibrous grafts consisted of PEAs and poly(ε-caprolactone)(PCL)in given mass ratios were further prepared via blend *** characterizations by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed the chemical structure,and the wettability indicated that the prepared PCL/PEAs electrospun membranes exhibited less hydrophobic than *** results showed that the PCL/PEAs membranes possessed suitable mechanical properties,which could meet the requirements of artificial blood *** culture and hemolytic tests exhibited that the PCL/PEAs electrospun membranes are *** general,the electrospun grafts of PCL/PEAs could be applied for vascular repair.

关键词： Poly(ester amide) Poly(ε-caprolactone) Electrospun membrane Mechanical property Vascular repair

Bacteria Adherence Properties of Nitrided Layer on Ti6Al4V by the Plasma Nitriding Technique

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Journal of Wuhan University of Technology(Materials Science) 2013年第6期28卷 1223-1226页

作者： FAN Ailan zhang Huiqiao MA Yong zhang xiangyu zhang Jianqiang TANG Bin Research Institute of Surface Engineering Taiyuan University of Technology College of Environmental Engineering Taiyuan University of Technology Department of Architectural Engineering Shanxi Polytechnic College

The nitrided layer on Ti6A14V substrate was prepared by the plasma nitriding technique. The sample was characterized by X-ray diffraction （XRD）, glow discharge optical emission spectroscopy （GDOES）, X-ray photoelectron spectroscopy （XPS）, and rough-meter. X- ray diffraction analysis reveals that TiN, Ti2N and Ti phase exist in the nitrided layer subsurface. GDOES analysis shows the thickness of the nitrided layer is about 3 ~tm. XPS analysis shows that there is higher N, lower A1 and lower V in the nitrided layer surface than in the Ti6A14V surface. Rough-meter analysis results show the roughness of the nitrided layer is greater than that of Ti6A14V alloy base. The bacteria adherence property of the nitrided layer on Ti6A14V substrate on the Streptococcus mutans was investigated and compared with that of Ti6A14V alloy by fluorescence microscope. It shows that the nitrided layer inhibits the bacteria adherence.

关键词： Ti6A14V plasma nitriding technique nitrided layer bacteria adherence property

A New Understanding of the Sedimentary Environment of the Laiyang Group in the Lower Cretaceous of Lingshan Island,Shandong Province,East China

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Acta Geologica Sinica(English Edition) 2020年第5期94卷 1325-1338页

作者： zhang xiangyu LI Shoujun ZHAO Xiuli GENG Geng YAN Mingming College of Earth Science&Engineering Shandong University of Science and TechnologyQingdaoShandong 266590China Key Laboratory of Stratigraphy and Palaeontology Ministry of Natural ResourcesBeijing 100037China

The sedimentary background and sedimentary environment of the Lower Cretaceous of Lingshan Island,Shandong,remain *** is considerable controversy as to whether the sedimentary environment was marine or *** this study,analyses were conducted with respect to indicators of paleosalinity,the chemical composition of clay,paleobiota,the characteristics of strata exhibiting salinization in eastern China during the Early Cretaceous,and the relationship between paleosalinity and *** results indicate that the sedimentary environment of the Lower Cretaceous Laiyang Group of Lingshan Island was that of a salified lake rather than a marine *** study not only provides a reference for determining the sedimentary environment of the Lower Cretaceous Laiyang Group of Lingshan Island but also offers a new perspective for the study of Cretaceous strata with salinization characteristics in eastern China.

关键词： paleobiota paleosalinity paleoclimate salified lake Lower Cretaceous Lingshan Island

Automated regression test method for scientific computing libraries:Illustration with SPHinXsys

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Journal of Hydrodynamics 2024年第3期36卷 466-478页

作者： Bo zhang Chi zhang xiangyu Hu TUM School of Engineering and Design Technical University of MunichMunichGermany

Scientific computing libraries,whether in-house or open-source,have witnessed enormous progress in both engineering and scientific ***,it is important to ensure that modifications to the source code,prompted by bug fixing or new feature development,do not compromise the accuracy and functionality that have been already validated and *** paper introduces a method for establishing and implementing an automatic regression test environment,using the open-source multi-physics library SPHinXsys as an illustrative ***,a reference database for each benchmark test is generated from observed data across multiple *** comprehensive database encapsulates the maximum variation range of metrics for different strategies,including the time-averaged,ensemble-averaged,and dynamic time warping *** accounts for uncertainties arising from parallel computing,particle relaxation,physical instabilities,and ***,new results obtained after source code modifications undergo testing based on a curve-similarity comparison against the reference *** the source code is updated,the regression test is automatically executed for all test cases,providing a comprehensive assessment of the validity of the current *** regression test environment has been successfully implemented in all dynamic test cases within SPHinXsys,including fluid dynamics,solid mechanics,fluid-structure interaction,thermal and mass diffusion,reaction-diffusion,and their multi-physics couplings,and demonstrates robust capabilities in testing different *** is noted that while the current test environment is built and implemented for a particular scientific computing library,its underlying principles are generic and can be easily adapted for use with other libraries,achieving equal effectiveness.

关键词： Scientific computing open-source library verification and validation regression test automatic test environment curve similarity comparison smoothed particle hydrodynamics

Experimental study on ageing characteristics of electric locomotive ethylene propylene rubber cable under mechanical-thermal combined action

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High Voltage 2022年第4期7卷 792-801页

作者： Lijun Zhou Cong Liu Shengwei Quan xiangyu zhang Dongyang Wang School of Electrical Engineering Southwest Jiaotong UniversityChengduChina

The train-mounted ethylene propylene rubber(EPR)cables of electric locomotive are partly restricted by the body structure and spatial layout and are in a combined envi-ronment of strong mechanical bending and thermal *** degradation character-istics of the insulation layer have not yet received sufficient *** order to study the ageing characteristics of EPR cables of electric locomotive under the combined action of machine and thermal,this paper designs a bending-thermal combined ageing test platform for cables with a temperature of 135°C,bending diameter of 393.52 mm,590.28 mm and unbending cables,and tests after *** product has been tested by infrared spectroscopy,scanning electron microscopy,elongation at break and broadband dielectric *** research results show that the bending outer part of the train-mounted EPR cable is a pain *** the combined action of bending and thermal,whether it is microstructure or macro performance,the degradation rate and degree of the bending of outer insulation layer are greater than the value under a single thermal ageing *** bending has an accelerating effect on the ageing of the EPR insulation *** research results can provide a reference for the ageing characteristics of the train-mounted EPR cable under the bending-thermal synergy and the evaluation of operating state of the train-mounted EPR cable under bending-thermal operating conditions.

关键词： microstructure thermal bending

Catalytic urea hydrolysis by composite metal oxide catalyst towards efficient urea-based SCR process:performance evaluation and mechanism investigation

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Frontiers of Environmental Science & Engineering 2023年第5期17卷 67-80页

作者： Yuchen Li Zhen Chen xiangyu zhang Kun Yang Lidong Wang Junhua Li MOE Key Laboratory of Resources and Environmental Systems Optimization Department of Environmental Science and EngineeringNorth China Electric Power UniversityBeijing 102206China State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China Xi’an Thermal Power Research Institute Co. Xi’an 710032China

As a promising option to provide gaseous NH_(3) for SCR system,catalytic urea hydrolysis has aroused great attention,and improving surface area and activity of catalysis are the crucial issues to be solved for efficient urea ***,a composite metal oxide(TiO_(2)@Al_(2)O_(3))catalyst was prepared by a simple hydrothermal method,with mesoporous alumina(γ-Al_(2)O_(3))as *** results verify the mesoporous structure and submicron cluster of TiO_(2)@Al_(2)O_(3),with exposed crystal faces of(101)and(400)for TiO_(2)andγ-Al_(2)O_(3),*** electronegativity difference of Ti4+and Al3+changes the charge distribution scheme around the interface,which provides abundant acid/base sites to boost the urea ***,for an optimal proportioning with nano TiO_(2)content at 10 wt.%,the hydrolysis efficiency can reach up to 35.2%at 100℃ in 2 h,increasing by~7.1%than that of the blank experiment.^(13)C NMR spectrum measurements provide the impossible intermediate species during urea *** calculations are performed to clarify the efficient H_(2)O decomposition at the interface of TiO_(2)@Al_(2)O_(3).The result offers a favorable technology for energy-efficiency urea hydrolysis.

关键词： SCR Urea hydrolysis Catalytic Water dissociation Electronegativity

Reinforcement learning building control approach harnessing imitation learning

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Energy and AI 2023年第4期14卷 60-72页

作者： Sourav Dey Thibault Marzullo xiangyu zhang Gregor Henze Department of Civil Environmental and Architectural EngineeringUniversity of ColoradoBoulderCOUSA National Renewable Energy Laboratory GoldenCOUSA Renewable and Sustainable Energy Institute BoulderCOUSA

Reinforcement learning(RL)has shown significant success in sequential decision making in fields like autonomous vehicles,robotics,marketing and gaming *** success has attracted the attention to the RL control approach for building energy systems which are becoming complicated due to the need to optimize for multiple,potentially conflicting,goals like occupant comfort,energy use and grid ***,for real world applications,RL has several drawbacks like requiring large training data and time,and unstable control behavior during the early exploration process making it infeasible for an application directly to building control *** address these issues,an imitation learning approach is utilized herein where the RL agents starts with a policy transferred from accepted rule based policies and heuristic *** approach is successful in reducing the training time,preventing the unstable early exploration behavior and improving upon an accepted rule-based policy-all of these make RL a more practical control approach for real world applications in the domain of building controls.

关键词： Reinforcement learning Building controls Imitation learning Artificial intelligence

测试工装引起的单板FPGA失效分析及改进方案

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电工技术 2024年第14期 159-165,176页

作者：秦健徐伟强高礼张祥钰特变电工新疆新能源股份有限公司陕西西安710000

针对某直流输电工程单板出现的FPGA失效故障,以故障FPGA失效表现为出发点,分析单板FPGA失效背景与原因,审视单板测试工装原理及测试方案,并针对问题提出整改措施。

关键词： FPGA失效电应力继电器接触器工装测试