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A Data-driven Method for Transient Stability Margin Prediction Based on Security Region

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Journal of Modern Power Systems and Clean Energy 2020年第6期8卷 1060-1069页

作者： Jun An jiachen Yu Zonghan Li Yibo Zhou Gang Mu the Key Laboratory of Modern Power System Simulation and Control&Renewable Energy Technology(Northeast Electric Power University) Ministry of EducationJilin 132012China China Electric Power Research Institute Beijing 100192China

Transient stability assessment(TSA)based on security region is of great significance to the security of power systems.In this paper,we propose a novel methodology for the assessment of online transient stability margin.Combined with a geographic information system(GIS)and transformation rules,the topology information and pre-fault power flow characteristics can be extracted by 2 D computer-vision-based power flow images(CVPFIs).Then,a convolutional neural network(CNN)-based comprehensive network is constructed to map the relationship between the steady-state power flow and the generator stability indices under the anticipated contingency set.The network consists of two components:the classification network classifies the input samples into the credibly stable/unstable and uncertain categories,and the prediction network is utilized to further predict the generator stability indices of the categorized samples,which improves the network ability to distinguish between the samples with similar characteristics.The proposed methodology can be used to quickly and quantitatively evaluate the transient stability margin of a power system,and the simulation results validate the effectiveness of the method.

关键词： Security region computer-vision-based power flow image(CVPFI) transient stability margin convolutional neural network(CNN) comprehensive network

(Hf_(0.5)Ta_(0.5))C ultra-high temperature ceramic solid solution nanowires

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Journal of Materials Science & Technology 2023年第16期147卷 91-101页

作者： Hui Chen Yulei Zhang Yanqin Fu jiachen Meng Qing Miao Jianhua Zhang Hejun Li State Key Laboratory of Solidification Processing Carbon/Carbon Composites Research CenterNorthwestern Polytechnical UniversityXi’an 710072China Carbon Matrix Composites Research Institute Henan Academy of SciencesZhengzhou 450046China

Ultra-high temperature ceramic(UHTC)nanowires are potential reinforcement materials due to it combines the perfect properties of bulk materials and unique geometric properties of one-dimensional(1D)nanostructures.Thus,developing 1D nanomaterials that have excellent morphology and structure retention in ultra-high temperature environments is of prime importance to bring their outstanding performance into full play.Herein,we report the novel solid solution((Hf_(0.5)Ta_(0.5))C)ceramic nanowires,which could not only maintain morphological and structural stability at 1900°C but also exhibit 1D nanostructures under oxyacetylene scouring and ablation at 2300°C.The morphology evolution of nanowires obeys the Rayleigh instability mechanism,and the internal structure and element distribution of nanowires remain unchanged even if the surface atoms are rearranged.The fascinating nanowires are demonstrated to have great potential as ideal reinforcement materials of composite materials and toughening phases of ceramics that are applied in ultra-high temperature environments,as well as excellent performance enhancement phases of functional materials.Our work may provide new insights into the development of ceramic nanowires and widen their applications.

关键词： (Hf_(0.5)Ta_(0.5))C solid solution nanowires Vapor-liquid-solid mechanism Catalyst/nanowire interface High-temperature stability Ablation resistance

Mixing and segregation of binary mixtures of biomass and silica sand in a fluidized bed

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Particuology 2021年第5期19卷 58-73页

作者： Tolu Emiola-Sadiq jiachen Wang Lifeng Zhang Ajay Dalai Department of Chemical and Biological Engineering University of Saskatchewan.SaskatoonSK S7N 5A9Canada

In this work,mixing and segregation of binary mixtures involving biomass materials in a fluidized bed was experimentally investigated.A frozen bed method was employed to investigate both axial and radial distribution of biomass particles in silica sand.Three different biomass materials were studied:willow sawdust,pelletized soy and oat hull materials.Biomass loading investigated ranged from 5% to 30% by weight.The extent of mixing for each of the biomass composition was investigated using Lacey’s mixing index which is based on the standard deviations of the sample at different axial positions in the bed.The radial composition was also investigated by means of digital imaging analysis using a high-resolution digital camera.The experiments revealed the differences in the extent of particle distribution for pelletized biomass materials vs non-densified materials as a result of differences in particle size,density and importantly,the particle shape of the materials utilized.The results showed an increase in the extent of mixing as the fluidizing velocity increased for both pellet materials while the mixing index for sawdust decreased beyond a loading of 20%.With an increase in biomass loading,an increase in mixing index was found for the two pellet materials.A similar trend was observed for sawdust at the lower loading level.However,the mixing index started to decrease at higher loading level beyond 20%.The results greatly contributed to the understanding of the hydrodynamics of binary and multicomponent mixtures involving biomass materials,especially pelletized materials in fluidized beds.

关键词： Mixing Segregation Biomass Binary Fluidization Pellets

水夹层式pVTt标准装置容器温度场数值模拟

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江苏大学学报（自然科学版） 2019年第6期40卷 655-661页

作者：李伯全陈彩俊张嘉琛石建荣江苏大学机械工程学院江苏镇江212013 江苏省质量技术监督气体流量计量检测中心江苏镇江212000

针对pVTt法气体流量标准装置运行过程中存在容器内气体稳定时间逐渐变长的问题,探索标准装置容器内温度场快速稳定的机理和途径,建立其双向流固热耦合数学模型及自然恒温模式和水夹层式恒温模式下的温度场仿真模型.采用COMSOL多物理场... 详细信息

针对pVTt法气体流量标准装置运行过程中存在容器内气体稳定时间逐渐变长的问题,探索标准装置容器内温度场快速稳定的机理和途径,建立其双向流固热耦合数学模型及自然恒温模式和水夹层式恒温模式下的温度场仿真模型.采用COMSOL多物理场耦合软件对进气过程和恒温过程进行了仿真和试验对比分析.结果表明:水夹层式恒温模式可以有效消除自然恒温模式下存在的严重温度梯度现象,缩短标准装置容器内气体稳定时间;影响标准装置容器内气体快速稳定的主要因素是容器进气气源温度和水夹套中水温间的温度差,保持水夹套中水温与标准装置进气气源温度基本一致,可以有效缩短标准容器内气体稳定时间,提高气体流量计检定工作效率.

关键词：水夹层 pVTt 双向流固热耦合 COMSOL 数值模拟

An Open-circuit Fault Diagnosis Method for PMSM Drives Using Symmetrical and DC Components

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Chinese Journal of Electrical Engineering 2021年第3期7卷 124-135页

作者： Wentao Huang jiachen Du Wei Hua Qigao Fan School of Internet of Things Engineering Jiangnan UniversityWuxi 214122China School of Electrical Engineering Southeast UniversityNanjing 201196China

In this paper,a diagnostic method based on symmetrical and DC components is presented for multiple open-circuit faults(OCFs)in a three-phase permanent magnet synchronous motor drive.The remaining phase currents under faulty situations are theoretically analyzed based on the Fourier series method and the mechanism of torque generation.To evaluate the asymmetry and discriminate fault types,the magnitude ratio of the positive sequence to the negative sequence of phase currents is designed as a fault detection index.Thereafter,the DC components of the phase currents in different reference frames are utilized to locate faults.Specifically,the polarities of the DC contents in the natural reference frame are utilized to locate a single OCF and two OCFs in different legs.Two OCFs in the same leg are diagnosed by evaluating the signs of the phase currents in the dq reference frame with a negative rotating direction.The simulated and experimental results validate the effectiveness of the developed method in fault detection and robustness against operating point and motor parameter variations.

关键词： Permanent magnet synchronous motor open-circuit fault fault diagnosis symmetrical component

The patterns and participants of parental histone recycling during DNA replication in Saccharomyces cerevisiae

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Science China(Life Sciences) 2023年第7期66卷 1600-1614页

作者： Zhongqing Shan Yan Zhang jiachen Bu Huizhi Li Zhuqiang Zhang Jun Xiong Bing Zhu National Laboratory of Biomacromolecules CAS Center for Excellence in BiomacromoleculesInstitute of BiophysicsChinese Academy of SciencesBeijing100101China College of Life Sciences University of Chinese Academy of SciencesBeijing100049China

Epigenetic information carried by histone modifications not only reflects the state of gene expression,but also participates in the maintenance of chromatin states and the regulation of gene expression.Recycling of parental histones to daughter chromatin after DNA replication is vital to mitotic inheritance of epigenetic information and the maintenance of cell identity,because the locus-specific modifications of the parental histones need to be maintained.To assess the precision of parental histone recycling,we developed a synthetic local label-chasing system in budding yeast Saccharomyces cerevisiae.Using this system,we observed that parental histone H3 can be recycled to their original position,thereby recovering their position information after DNA replication at all tested loci,including heterochromatin boundary,non-transcribed region,and actively transcribed regions.Moreover,the recycling rate appears to be affected by local chromatin environment.We surveyed a number of potential regulatory factors and observed that histone H3-H4 chaperon Asf1 contributed to parental histone recycling,while the eukaryotic replisome-associated components Mcm2 and Dpb3 displayed compounding effects in this process.In addition,the FACT complex also plays a role in the recycling of parental histones and helps to stabilize the nucleosomes.

关键词： epigenetic inheritance parental histone recycling Asf1 Mcm2 Dpb3 FACT

固相萃取-超高效液相色谱-串联质谱法检测粮食及其制品中的玉米赤霉烯酮类真菌毒素

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色谱 2010年第6期28卷 601-607页

作者：孟娟张晶张楠施嘉琛邵兵北京市疾病预防控制中心北京100013

建立了粮食及其制品中6种玉米赤霉烯酮类物质(α-玉米赤霉醇、β-玉米赤霉醇、α-玉米赤霉烯醇、β-玉米赤霉烯醇、玉米赤霉酮和玉米赤霉烯酮)的超高效液相色谱-串联质谱(UPLC-MS/MS)检测方法。样品用84%(体积分数)乙腈水溶液提取,通过E... 详细信息

建立了粮食及其制品中6种玉米赤霉烯酮类物质(α-玉米赤霉醇、β-玉米赤霉醇、α-玉米赤霉烯醇、β-玉米赤霉烯醇、玉米赤霉酮和玉米赤霉烯酮)的超高效液相色谱-串联质谱(UPLC-MS/MS)检测方法。样品用84%(体积分数)乙腈水溶液提取,通过ENVI-Carb石墨化炭黑(GCB)固相萃取柱进行富集净化,用6mL二氯甲烷-甲醇(7∶3,v/v)溶液洗脱,采用UPLC-MS/MS进行测定。在ACQUITY UPLCTMBEH C18反相柱上分离,梯度洗脱,流动相为水和乙腈;质谱采集模式为电喷雾负离子多反应监测模式。以α-玉米赤霉烯酮-d4为内标,6种目标物的线性范围为0.1～50μg/L,相关系数(R2)大于0.99,检出限为0.1～0.2μg/kg,3个不同水平的加标平均回收率为79.9%～104.0%,相对标准偏差不大于10%。应用该方法对北京市的粮食及相关产品进行了分析,结果发现玉米赤霉烯酮的检出率最高,含量为0.42～220.7μg/kg;此外还检出了α-和β-玉米赤霉烯醇。该方法具有操作简单、灵敏度高、重现性好等特点,符合食品样品中痕量污染物的检测要求。

关键词：固相萃取超高效液相色谱-串联质谱玉米赤霉烯酮真菌毒素粮食粮食制品

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混凝土桥面沥青铺装病害原因及对策研究

上海公路 2019年第3期 1-4,9,M0002页

作者：朱天同姚鸿儒史佳晨同济大学道路与交通工程教育部重点实验室上海201804 上海城建日沥特种沥青有限公司上海200231

由于我国对混凝土桥面沥青铺装设计要求较低及其他原因,造成混凝土桥面沥青铺装病害频发,严重影响交通安全及社会经济发展。通过理论分析及实验研究,从设计因素、铺装结构、层间黏结、水损害及混合料本身性能等方面分析混凝土桥面沥青... 详细信息

由于我国对混凝土桥面沥青铺装设计要求较低及其他原因,造成混凝土桥面沥青铺装病害频发,严重影响交通安全及社会经济发展。通过理论分析及实验研究,从设计因素、铺装结构、层间黏结、水损害及混合料本身性能等方面分析混凝土桥面沥青铺装产生病害的原因。针对以上原因,提出了防排水相结合的设计思想、合适的铺装结构和沥青及相应混合料所需的性能指标以提高混凝土桥面沥青铺装的抗损害性能。此外,试验研究发现溶剂+涂膜类黏结材料在几种试验材料中性能最为优良。以上研究成果可为后续混凝土桥面沥青铺装新建及养护提供指导意见。

关键词：混凝土桥面沥青铺装病害原因解决方案

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显示触控系统人为因素适航符合性验证技术

中国安全科学学报 2021年第2期31卷 63-68页

作者：董磊刘嘉琛赵长啸党香俊史春蕾中国民航大学民航航空器适航审定技术重点实验室天津300300 中国民航大学适航学院天津300300 天津市民用航空器适航与维修重点实验室天津300300

为解决传统人为因素适航符合性验证技术对先进驾驶舱显示触控系统设计的不适用性问题,首先,详细阐述显示触控系统的技术特点;然后,依据相关适航条款,确定显示触控系统在人为因素适航审定中需重点考虑的要素和审定计划的条理性方法;最后... 详细信息

为解决传统人为因素适航符合性验证技术对先进驾驶舱显示触控系统设计的不适用性问题,首先,详细阐述显示触控系统的技术特点;然后,依据相关适航条款,确定显示触控系统在人为因素适航审定中需重点考虑的要素和审定计划的条理性方法;最后,结合符合性验证可能产生的问题,给出显示触控系统人为因素符合性验证要求及实现方法。结果表明:人为因素适航符合性验证技术能够在符合性验证方法的框架内,通过位置和可达性、功能和可靠性等6个方面的要求,实现显示触控系统的人为因素适航符合性验证。

关键词：民机驾驶舱触控屏人为因素适航审定符合性验证