检索结果-南通市图书馆

PCA weight and Johnson transformation based alarm threshold optimization in chemical processes

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2018年第8期26卷 1653-1661页

作者： Wende Tian guixin zhang Xiang zhang Yuxi Dong College of Chemical Engineering Qingdao University of Science & Technology

To alleviate the heavy load of massive alarm on operators, alarm threshold in chemical processes was optimized with principal component analysis(PCA) weight and Johnson transformation in this paper. First, few variables that have high PCA weight factors are chosen as key variables. Given a total alarm frequency to these variables initially, the allowed alarm number for each variable is determined according to their sampling time and weight factors. Their alarm threshold and then control limit percentage are determined successively. The control limit percentage of non-key variables is determined with 3σ method alternatively. Second, raw data are transformed into normal distribution data with Johnson function for all variables before updating their alarm thresholds via inverse transformation of obtained control limit percentage. Alarm thresholds are optimized by iterating this process until the calculated alarm frequency reaches standard level(normally one alarm per minute). Finally,variables and their alarm thresholds are visualized in parallel coordinate to depict their variation trends concisely and clearly. Case studies on a simulated industrial atmospheric-vacuum crude distillation demonstrate that the proposed alarm threshold optimization strategy can effectively reduce false alarm rate in chemical processes.

关键词： Alarm threshold Chemical process PCA Johnson transformation Variable weight

Spatial Distribution of High-temperature Risk with a Return Period of Different Years in the Yangtze River Delta Urban Agglomeration

在线全文

学校读者我要写书评

暂无评论

Chinese Geographical Science 2022年第6期32卷 963-978页

作者： zhang guixin WANG Shisheng ZHU Shanyou XU Yongming School of Geographical Sciences Nanjing University of Information Science&TechnologyNanjing 210044China Academy of Environmental Planning&Design CO. LTD.Nanjing UniversityNanjing 210093China School of Remote Sensing and Geomatics Engineering Nanjing University of Information Science&TechnologyNanjing 210044China

Against the background of global warming,research on the spatial distribution of high-temperature risk is of great significance to effectively prevent the adverse effects of high *** using air temperature data from 1951 to 2018 measured by meteorological stations located in the Yangtze River Delta urban agglomeration,the daily maximum air temperature distribution is interpolated at a resolution of 1 km based on the local thin disk smooth spline function;the high-temperature threshold for return periods of 5,10,20 and 30 yr are then calculated by using the generalized extreme value *** yearly average high-temperature intensity and high-temperature days are finally calculated as high-temperature danger *** statistical data and remotely sensed image data in 2018 are used as the background data to calculate the spatial distribution of high-temperature vulnerability factors and prevention capacity factors,which are then used to compute the high-temperature risk index during different recurrence periods in the Yangtze River Delta urban *** results show that the spatial distribution features of high-temperature risk in different return periods are *** high-temperature risk index gradually increases from northeast to southwest and from east coast to inland,which has obvious latitude variation characteristics and a relationship with the comprehensive influence of the underlying surface and urban *** terms of time variation,the high-temperature risk index and its spatial distribution difference gradually decreases with increasing return *** different cities,the high-temperature risk in the central area of the city is generally higher than that in the surrounding suburban ***,Hangzhou of Zhejiang Province and Xuancheng of Anhui Province are the top three cities with high-temperature risk in the study area.

关键词： high-temperature risk generalized extreme value method recurrence period remote sensing spatialization

Charge accumulation characteristic on polymer insulator surface under AC voltage in air and C_(4)F_(7)N/CO_(2)mixtures

在线全文

学校读者我要写书评

暂无评论

High Voltage 2020年第2期5卷 160-165页

作者： Dayu Li guixin zhang Tianyu Wang Yicen Hou Department of Electrical Engineering Tsinghua UniversityBeijingPeople's Republic of China

Charge accumulation has always been a problem for the safe operation of gas insulated switchgear(GIS)/gas insulated transmission line(GIL)both under AC and *** is of great significance to investigate the behaviour of surface charge under high *** this study,the charge distribution characteristics and accumulation mechanism on insulator surface in air and heptafluorobutyronitrile/carbon dioxide(C_(4)F_(7)N/CO_(2))mixtures under AC voltage are studied via the means of surface potential measurement and inversion algorithm,combined with the improved method of controlling the truncated phase of AC *** results show that under the needle–plate electrode structure,charge distribution on the insulator surface presents a three-tier concentric circle structure both in air and C_(4)F_(7)N/CO_(2) gas mixtures,and the charge composition of the innermost circle is closely related to the truncated phase of AC *** the same amplitude of voltage,the range of charge distribution on insulator surface in C_(4)F_(7)N/CO_(2) mixtures is smaller than that in air,with the negative charges *** is suggested that the characteristic of charge distribution in C_(4)F_(7)N/CO_(2) mixtures is related to the larger electron attachment crosssection of C4F7N gas in a wide range of electron energy distribution.

关键词： surface insulator charge

Monitoring Spatio-temporal Variance of an Extreme Heat Event Using Multiple-source Remote Sensing Data

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Geographical Science 2018年第5期28卷 744-757页

作者： ZHU Shanyou LIU Yi HUA Junwei zhang guixin ZHOU Yang XIANG Jiamin School of Remote Sensing and Geomatics Engineering Nanjing University of Information Science & Technology Nanjing 210044China Chuzhou Meteorological Bureau Chuzhou 239001 China

Extreme heat events have serious effects on human daily life. Accurately capturing the dynamic variance of extreme high-temperature distributions in a timely manner is the basis for analyzing the potential impacts of extreme heat, thereby informing risk prevention strategies. This paper demonstrates the potential application of multiple source remote sensing data in mapping and monitoring the extreme heat events that occurred on Aug. 8, 2013 in Jiangsu Province, China. In combination with MODIS products, the thermal sharpening(Ts HARP) method and a binary linear model are compared to downscale the original daytime FengY un 2 F(FY-2 F) land surface temperature(LST) imagery, with a temporal resolution of 60 min, from 5 km to 1 km. Using the meteorological measurement data from Nanjing station as the reference, the research then estimates the instantaneous air temperature by using an iterative computation based on the Surface Energy Balance Algorithm for Land(SEBAL), which is used to analyze the spatio-temporal air temperature variance. The results show that the root mean square error(RMSE) of the LST downscaled from the binary linear model is 1.30℃ compared to the synchronous MODIS LST, and on this basis the estimated air temperature has the RMSE of 1.78℃. The spatial and temporal distribution of air temperature variance at each geographical location from 06:30 to 18:30 can be accurately determined, and indicates that the high temperature gradually increases and expands from the city center. For the spatial distribution, the air temperature and the defined scorching temperature proportion index increase from northern to middle, to southern part of Jiangsu, and are slightly lower in the eastern area near the Yellow Sea. In terms of temporal characteristics, the percentage of area with air temperature above 37℃ in each city increase with time after 10:30 and reach the peak value at 14:30 or 15:30. Then, they decrease gradually, and the rising and falling trends become s

关键词： extreme heat events land surface temperature air temperature downscale remote sensing

Review of Charge Accumulation on Spacers of Gas Insulated Equipment at DC Stress

在线全文

学校读者我要写书评

暂无评论

CSEE Journal of Power and Energy Systems 2020年第3期6卷 496-517页

作者： Hongyang Zhou Guoming Ma Cong Wang Jue Wang guixin zhang Youping Tu Chengrong Li State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources and the Beijing Key Laboratory of High Voltage and EMC North China Electric Power UniversityBeijing 102206China Institute of Electrical Engineering Chinese Academy of SciencesBeijingChina Department of Electrical Engineering Tsinghua UniversityBeijing 100084China

Charge accumulation on the spacer surface in gas insulated equipment is very severe in the DC field,leading to easy flashover,which restricts the application of DC GIS/***,knowledge about the charge accumulation characteristics of gas insulated equipment at DC stress is *** this paper,we reviewed the research methods and the characteristics of charge accumulation on spacers.A summary of charge measurement methods and setups are *** the surface charge inversion algorithms are *** the simulation model for charge accumulation in the DC field is ***,the charge accumulation mechanisms and phenomenon,the influence factor of surface charge accumulation and the influence of accumulated charge on spacer insulation characteristics are *** addition,some suppression methods of surface charge accumulation are ***,based on the understanding of charge accumulation on spacers,some suggestions on further studies are presented to aid in the design of a better spacer free from surface charges.

关键词： Charge accumulation DC gas insulated equipment review spacer

The Wenchuan earthquake creation of a rich database of building performance

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2010年第10期53卷 2668-2680页

作者： SUN BaiTao & zhang guixin Institute of Engineering Mechanics, China Earthquake Administration, Harbin 150080, China 1. Institute of Engineering Mechanics China Earthquake Administration Harbin 150080 China

After the Wenchuan earthquake,The Institute of Engineering Mechanics (IEM) performed an extensive and comprehensive damage survey of the large area affected by the earthquake. Seismic codes in China were revised and updated after the catastrophic 1976 Tangshan earthquake. However,until the Wenchuan earthquake the seismic code provisions were not tested by a large earthquake. Some 5000 buildings,exposed to intensities VI to XI,were investigated in great detail immediately after the earthquake. The investigation and the surveys covered both seismically designed (fortified) buildings and non-code compliant buildings. In the process a comprehensive and documented database of building performance was compiled,which would be very valuable for further research,improvement of the seismic code,improvement of the construction practices,and disaster mitigation planning and management. The database dominantly contains the most prevalent structural types in the region: 1) reinforced and un-reinforced masonry structures; 2) masonry buildings with reinforced frame in the lower stories,and 3) reinforced concrete frame structures. Observed damage characteristics of various structural types were studied and documented,damage patterns analyzed,and corresponding damage probability matrices derived from the data collected during this survey. It is our hope that this investigation and the published material will be utilized for the revision of the seismic codes,leading to a higher level of life safety and damage reduction in future earthquakes.

关键词： Wenchuan earthquake building damage vulnerability damage probability matrices

Multiple fluorescence color transitions mediated by anion-π interactions and C-F covalent bond formation

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2023年第2期34卷 393-396页

作者： Jie Pan Wei Lin Fang Bao Qinglong Qiao guixin zhang Yao Lu Zhaochao Xu CAS Key Laboratory of Separation Science for Analytical Chemistry Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China China Department of Obstetrics and Gynecology The Affiliated Hospital of Qingdao UniversityQingdao 266000China General Surgery Department The First Affiliated Hospital of Dalian Medical UniversityDalian 116011China

The emission changes of fluorescent dyes under the influence of environmental changes or interaction with analytes are the basis for designing ratiometric fluorescent probes and logic gates. However, it is rare that only one external stimulus induces continuous fluorescent color changes in a fluorescent *** this paper, we report a cage-like molecule formed by two benzene rings and three imidazolium salts which produces continuous fluorescence wavelength changes when interacted with fluoride ions. Fluoride ions are first bound to the center of the cage under the action of anion-π interaction, and the(C-H)^(+)···F^(–)type ionic hydrogen bonds induce the blue-shift of fluorescence. The subsequent formation of C-F covalent bonds with fluoride ions makes the fluorophore wavelength continue to blue-shift, and finally obtains continuous multiple fluorescence changes caused by a single external stimulus. According to the fluorescence wavelength and intensity, six different fluorescence signal channels can be obtained,which can be encoded as six numbers from 0 to 5. We expect that this reaction process can find applications in quantitative anion recognition and molecular counters.

关键词： Anion-π Imidazolium C-F bond Miltple color Fluorescent probe

A fluorogenic probe for SNAP-tag protein based on ESPT ratiometric signals

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2023年第5期34卷 641-644页

作者： Jin Li Qinglong Qiao Yiyan Ruan Ning Xu Wei Zhou guixin zhang Jingli Yuan Zhaochao Xu State Key Laboratory of Fine Chemicals School of ChemistryDalian University of TechnologyDalian 116024China CAS Key Laboratory of Separation Science for Analytical Chemistry Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China University of Chinese Academy of Sciences Beijing 100049China General Surgery Department The First Affiliated Hospital of Dalian Medical UniversityDalian 116011China

Protein self-labeling tags achieve selective fusion and labeling of target proteins through genetic coding technology,but require exogenous fluorescent probes with fluorogenicity for protein tag binding to have the performance of wash-free fluorescence imaging in live *** this paper,we reported a fluorogenic probe 1 capable of ratiometric fluorescence recognition of SNAP-tag *** this probe,the O6-benzylguanine derivative of 3-hydroxy-1,8-naphthalimide underwent a selective covalent linkage reaction with SNAP-tag *** hydroxyl group on the naphthalimide fluorophore formed a hydrogen bond with the functional group near the protein *** excited state proton transfer occurred after illumination,to obtain the ratio fluorescence signal from blue emission to red emission,realizing the wash-free fluorescence imaging of the target proteins.

关键词： Fluorogenic probe Ratiometric ESPT SNAP-tag Wash-free imaging

直流GIL中固-气界面电荷特性研究综述Ⅰ:测量技术及积聚机理

在线全文

学校读者我要写书评

暂无评论

电工技术学报 2018年第22期33卷 4649-4662页

作者：张博雅张贵新西安交通大学电力设备电气绝缘国家重点实验室西安710049 清华大学电机工程与应用电子技术系北京100084

气体绝缘输电线路(GIL)是一种先进的输电方式,可满足特殊环境下的输电需求。然而,在直流电压下,GIL绝缘子表面存在显著的电荷积聚现象,极易引发沿面闪络,严重制约了GIL在直流工程中的应用。因此,开展直流GIL中固-气界面电荷特性的研究... 详细信息

气体绝缘输电线路(GIL)是一种先进的输电方式,可满足特殊环境下的输电需求。然而,在直流电压下,GIL绝缘子表面存在显著的电荷积聚现象,极易引发沿面闪络,严重制约了GIL在直流工程中的应用。因此,开展直流GIL中固-气界面电荷特性的研究具有重要意义。在此背景下,本系列文章综述了多年来国内外有关直流GIL中固-气界面电荷特性的主要研究成果。本文综述Ⅰ首先总结了目前测量表面电荷的三种主要方法,介绍了基于数字图像处理技术的电荷反演算法;其次,从早期研究基础和目前研究现状两方面重点分析固-气界面电荷的积聚机理和仿真模型,并提出电荷积聚可能存在的两种模式:"基本"模式和"电荷斑"模式;最后,从固-气界面电荷的测量技术、仿真模型和机理研究三方面对未来工作给出了相关建议。

关键词：直流气体绝缘输电线路表面电荷电荷积聚综述

同方期刊数据库