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Some Performance Measures of Transfer line Consisting of Two Unreliable Machines with Reprocess Rule

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Systems Science and Systems Engineering 1998年第3期8卷 27-36页

作者： li Wei CAO Jinhua institute of applied mathematics, chinese academy of sciences,beijing 100080

In this paper, we consider a transfer line with two unreliable machines and a single storage buffer, in which the second machine’s processing time and repair time have general distributions, and a piece processed by machine i will be reprocessed with probability q i (i=1, 2) because of uncompletely or not very well processed just before. At first, the exactly results of the reprocessed rate, the output rate and the blocked probability of machine 1, the reprocessed rate and the starved probability of machine 2, and the production rate of the system, are obtained when the first machine is reliable. And then, some approximating results of above indices are given when two machines are both unreliable.

关键词： transfer line reprocess rule blocked probability production rate.

SOME　PERFORMANCE　MEASURES　OF　REPAIRABLE　TRANSFER　liNE　WITH　GENERAL　DISTRIBUTIONS

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Systems Science and Mathematical sciences 1994年第4期7卷 344-351页

作者： li Wei CAO Jinhua(institute of applied mathematics, Academia Sinica, beijing 100080, china)(Open laboratory on the Complex System Control, institute of Automation,Academia Sinica, beijing 100080, china) 中科院应用数学所北京

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关键词： Transfer line vector Markov process

Characteristic Rainfall for Warning of Debris Flows

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Journal of Mountain Science 2010年第3期7卷 207-214页

作者： HU Kaiheng Cui Peng Wang Chuanchang li Yong Lu Xiaobing Key laboratory of Mountain Hazards and Earth Surface Processes Chinese Academy of Sciences Chengdu 610041 China institute of Mountain Hazards and Environment Chinese Academy of Sciences & Ministry of Water Conservancy Chengdu 610041 China institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

A characteristic rainfall is introduced to overcome the difficulties encountered in determining a critical rainfall value for triggering debris *** characteristic value is defined as the rainfall at which debris-flow occurrence probability shows a rapid increase,and can be used as a warning rainfall threshold for debris *** of recorded debris flows and 24-hour rainfall data at Jiangjia basin,Yunnan Province,in southwestern china,demonstrates the existence of such a characteristic *** was found that the characteristic rainfall corresponds to the daily rainfall of 90% cumulative probability by analyzing the basin's daily rainfall *** result provides a simple and useful method for estimating a debris-flow warning rainfall threshold from the daily rainfall *** was applied to estimate the debris-flow warning rainfall threshold for the Subaohe basin,a watershed in the 2008 Wenchuan earthquake zone with many physical characteristics similar to those of the Jiangjia basin.

关键词： Debris flow Wenchuan earthquake warning rainfall threshold statistics of daily rainfalldistribution

Some Bounds of Tail probability

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Some Bounds of Tail Probability

FLEXIBLE MAGNETIC WHEEL TYPE INTELliGENT WELDING ROBOT FOR SPHERICAL TANK

中国运筹学会第六届学术交流会

作者： li Gang CHENG Kaninstitute of applied mathematics, academy of mathematics and Systems sciences chinese academy of sciences, beijing 100080

For a special probability model, some upper bounds of tail probability are given by martingale, and some lower bounds of tail probability are given by Jensen and Lardan inequality.

关键词： Bounds Supermartingale NWU NBUE Inequality

来源： cnki会议评论

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cnki会议

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chinese Journal of Mechanical Engineering 2002年第2期15卷 173-176页

作者： Jiang lipei Jiao xiangdong Xue Long Ma Hongze li Mingli Yang Zhaochun Department of Mechanical Engineering, institute of Petro-chemical Technology,beijing 102600, china 北京石油化工学院北京 102600

An intelligent welding robot for spherical tank's all-position multi-layerwelds is developed. Based on the dynamics analyzing and simulation testing, a flexible magneticwheel mechanism is created as the robot's walking carriage. It makes the robot directly attracted tothe surface of the spherical tank so as to realize the all-position walking and welding withoutrail. At the same time, a CCD real-time tracing system is developed for the robot to repeatedlytrace the all-position and multi-layer seams. The welding tests show that the welding robot can makethe all-position and multi-layer welds with high tracing accuracy, excellent quality and reliablebehavior, and it can be applied for practical production.

关键词： Welding robot All-position welding Automatic welding Spherical tank

基于实测弓网接触力的高速铁路接触线疲劳寿命研究

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中国铁道科学 2024年第4期45卷 168-179页

作者：李向东韦友春代林峰北京铁科英迈技术有限公司北京100081 中国国家铁路集团有限公司工电部北京100089 中国铁路成都局集团有限公司重庆供电段重庆400053

针对传统仿真计算方法得到的弓网接触力不能用于准确分析实际运营时复杂环境因素影响下的接触线疲劳寿命问题,在接触线受力分析基础上,借助高速综合检测车并基于弓网等效质量模型,通过采集的弓网垂向接触力、补偿加速度和气动抬升力得... 详细信息

针对传统仿真计算方法得到的弓网接触力不能用于准确分析实际运营时复杂环境因素影响下的接触线疲劳寿命问题,在接触线受力分析基础上,借助高速综合检测车并基于弓网等效质量模型,通过采集的弓网垂向接触力、补偿加速度和气动抬升力得到弓网接触力实测数据,再采用雨流计数法对其进行压缩、提取峰谷值、循环计数等处理;在此基础上,结合接触线材料特性得到接触线疲劳寿命及单弓运行下上下行接触线的安全运行年限,对比分析单弓运行、双弓运行及检修前后弓网接触力对接触线疲劳寿命的影响。结果表明:线路各锚段内接触线疲劳寿命差异较大,通常定位点或吊弦处等质量负荷集中处的接触线疲劳寿命较低;单弓运行下接触线最小安全运行年限为13.05 a,双弓运行为10.03 a,小于单弓运行;接触网检修后,单弓运行下最小安全运行年限提升为17.78 a,整体运行安全年限在17.78~28.38 a之间。

关键词：高速铁路接触线疲劳寿命雨流计数法弓网接触力

基于原子层沉积技术的X射线多层膜的制备研究

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光学学报 2024年第4期44卷 363-369页

作者：吕文思吴宏昌李艳丽孔祥东韩立中国科学院电工研究所北京100190 中国科学院大学电子电气与通信工程学院北京100049 兰州大学物理科学与技术学院甘肃兰州730000

X射线多层膜是X射线光学领域的重要反射元件,可利用X射线的布拉格反射实现特定波段X射线的高效反射。多层膜的反射率与膜层材料和膜层结构密切关系,根据多层膜的工作原理,对于高能波段的X射线,为获得较大掠射角下的高反射率,通常需要多... 详细信息

X射线多层膜是X射线光学领域的重要反射元件,可利用X射线的布拉格反射实现特定波段X射线的高效反射。多层膜的反射率与膜层材料和膜层结构密切关系,根据多层膜的工作原理,对于高能波段的X射线,为获得较大掠射角下的高反射率,通常需要多层膜具有更小的周期厚度和更大的周期数,因此高精度薄膜生长技术是X射线多层膜元件制备的必要条件。本文研究了基于原子层沉积技术的X射线多层膜的制备,首先利用Fresnel系数递推法计算出HfO_(2)/Al_(2)O_(3)、Ir/Al_(2)O_(3)、Ru/Al_(2)O_(3)、W/Al_(2)O_(3)四种材料组合的多层膜的反射率,讨论了材料组合、周期厚度、周期数、占空比等参数对多层膜反射率的影响。在此基础上,选取并制备了周期厚度为4 nm、周期数为60、占空比为0.5的HfO_(2)/Al_(2)O_(3)X射线多层膜。X射线(0.154 nm)反射率的分析结果显示,该多层膜的周期厚度为3.86 nm,反射率约43%,多层膜截面的透射电子显微镜(TEM)图显示膜层间界面清晰。该结果验证了原子层沉积法制备小周期厚度X射线多层膜元件的可行性。

关键词：原子层沉积 X射线多层膜反射率

Prediction of petroleum exploration risk and subterranean spatial distribution of hydrocarbon accumulations

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Petroleum Science 2011年第1期8卷 17-23页

作者： Xie Hongbing Guo Qiulin li Feng li Jianzhong Wu Na Hu Suyun liang Kun School of Energy Resources China University of GeosciencesBeijing 100083China Research institute of Petroleum Exploration ＆ Development PetroChinaBeijing 100083China Science ＆ Technology Management Department China National Petroleum CorporationBeijing 100007China

Investigation of spatial distribution of oil and gas resource and accurate prediction of the geographic location of its undiscovered resource is significant for reducing exploration risk and improving exploration benefit.A new method for predicting spatial distribution of oil resource is discussed in this *** consists of prediction of risk probability in petroleum exploration and simulation of hydrocarbon abundance. Exploration risk probability is predicted by multivariate statistics,fuzzy mathematics and information processing techniques.A spatial attribute database for sample wells was set up and the Mahalanobis distance and Fuzzy value of given samples were ***,the Bayesian formula was used to calculate the hydrocarbon-bearing probability at the area of exploration ***,a hydrocarbon probability template is formed and used to forecast the probability of the unknown area. The hydrocarbon abundance is simulated based on Fourier integrals,frequency spectrum synthesis and fractal ***,the fast Fourier transformation（FFT） is used to transform the known hydrocarbon abundance from the spatial domain to the frequency domain,then,frequency spectrum synthesis is used to produce the fractal frequency spectrum,and FFT is applied to get the phase information of hydrocarbon-bearing ***,the frequency spectrum simulation is used to calculate the renewed hydrocarbon abundance in the play. This method is used to predict the abundance and possible locations of the undiscovered petroleum accumulations in the Nanpu Sag of the Bohai Bay Basin,*** prediction results for the well-explored onshore area of the northern Nanpu Sag agree well with the actual *** the less-explored offshore areas in the southern Nanpu Sag,the prediction results suggest high hydrocarbon abundance in Nanpu-1 and Nanpu-2,providing a useful guiding for future exploration.

关键词： Hydrocarbon resources abundance risk forecast Nanpu sag frequency spectrum simulation fractal theory

Effect of helmet-wearing regulation on electric-bike riders:a case study of two cities in china

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Transportation Safety and Environment 2024年第3期6卷 62-70页

作者： Wenxin Ma Zhiyong liu Ruimin li Department of Civil Engineering Tsinghua UniversityBeijing 100084China School of Traffic and Transportation Beijing Jiaotong UniversityBeijing 100044China

Objectives:Electric bikes(e-bikes)are widely used for commuting and delivery in *** the rapid increase in e-bikes on the road,related accidents have become crucial issues threatening the *** research aims to explore the protective effect of helmet-wearing regulation and to investigate some factors influencing head injury with reference to two case cities in china,obtaining information to protect e-bike ***:The traffic police-reported crash data cover the periods before and after the implementation of helmet-wearing regulations in Taizhou(with data from 2017 to 2019)and Nanning(with data in 2020)of *** statistical analysis,logistic regression and chi-square test with a Bonferroni correction were applied in the ***:A lack of helmets was common among victims in the context of a high helmet-wearing rate among general e-bike riders in Taizhou,indicating that fatality could be avoided to some extent by wearing ***,helmet wearing could reduce the probability of suffering fatal head injury by 6.4%.After the regulation implementation in Taizhou,the proportion of fatal head injuries decreased from 89%to 79%,remaining at a high level,which indicates that other measures in addition to helmet-wearing regulations should be *** to the results from Nanning,mandatory regulation worked more effectively than encouraged regulation in terms of reducing head ***:Mandatory helmet-wearing regulations are highly recommended to policymakers to reduce head injury among e-bike *** in addition to helmet-wearing regulation,*** law-abiding awareness and improving road infrastructure,should be considered to further protect e-bike riders.

关键词： e-bike safety accident analysis helmet-wearing regulation head injury