检索结果-南通市图书馆

Discrete event model-based simulation for train movement on a single-line railway

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2014年第8期23卷 233-239页

作者：徐小明李克平杨立兴 State key laboratory of Rail Traffic control and Safety Beijing Jiaotong University beijing laboratory of Urban Rail Transit Beijing Jiaotong University

The aim of this paper is to present a discrete event model-based approach to simulate train movement with the con- sidered energy-saving factor. We conduct extensive case studies to show the dynamic characteristics of the traffic flow and demonstrate the effectiveness of the proposed approach. The simulation results indicate that the proposed discrete event model-based simulation approach is suitable for characterizing the movements of a group of trains on a single railway line with less iterations and CPU time. Additionally, some other qualitative and quantitative characteristics are investigated. In particular, because of the cumulative influence from the previous trains, the following trains should be accelerated or braked frequently to control the headway distance, leading to more energy consumption.

关键词： train movement discrete event model railway energy saving

A SIMULATION METHOD FOR ANALYZING AND EVALUATING RAIL SYSTEM PERFORMANCE BASED ON SPEED PROFILE

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science and Systems Engineering 2018年第6期27卷 810-834页

作者： Hangfei Huang Keping Li Yanhui Wang State key laboratory of Rail Traffic control and Safety Beijing Jiaotong University Beijing 100044 China

This paper presents and discusses a simulation method for analyzing and evaluating system performance on a rail line from the perspective of speed profile. Dynamic analysis for train motions is introduced, and a discrete time-operation graph is proposed to represent the relation between speed profile and energy consumption. Based on them, an analytical model is formulated to provide a quick insight into the system performance. The discrete-time simulation （DTS） method is then implemented to study the system in detail. Compared to the existing simulations, two innovations are included in the DTS：（1） the analytical lookup tables that can simplify the dynamic computation and, （2） the speed profile adjustment process that forecasts and avoids future conflicts based on practical constraints. The numerical results show that the DTS speed profile has advantages over existing methods. Finally, the DTS method is used to analyze and evaluate the system performance of the current timetable on beijing Yizhuang Metro Line. The results suggest that the current timetable is not robust enough, and thus possible improvements are discussed at both scheduling and operating stages. The proposed method is verified to be effective and reliable for practical uses.

关键词： Simulation speed profile discrete graph dynamic analysis system evaluation

Population divergence of aggregation pheromone responses in Ips subelongatus in northeastern China

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

Insect Science 2016年第5期23卷 728-738页

作者： Da-Feng Chen Ye-Jing Li Qing-He Zhang Su-Fang Zhang Hong-Bin Wang Zhen Zhang Li-Lin Zhao Xiang-Bo Kong key laboratory of forest Protection of State forestry Administration Research Institute of Forest Ecology Environment and Protection Chinese Academy of Forestry Beijing China State key laboratory of Integrated Management of pest Insects and Rodents Institute of Zoology Chinese Academy of Sciences Beijing China Sterling International Inc. Spokane Washington USA

The Asian larch bark beetle, Ips subelongatus, is considered to be the major pest of larch within its natural range. We investigated the electrophysiological and behavioral characteristics as well as mitochondrial DNA cytochrome oxidase subunit I sequences of L subelongatus from 13 geographic populations throughout northeastern China in order to explore population divergence of aggregation pheromone responses and the extent of potential genetic divergence. Electrophysiological analyses showed that antennae of I. sube-longatus from all the six tested populations responded strongly to （S）-（-）-ipsenol （100% detection; 0.35-0.73 mV） in gas chromatography （GC）-electroantennographic detection （EAD） analyses, while its antipode, （R）-（＋）-ipsenol was antennally inactive. I. subelon- gatus populations varied in their responses to （R）-（-）- and （S）-（＋）-ipsdienol in GC-EAD analyses. Behavioral bioassays demonstrated that （S）-（-）-ipsenol alone was significantly attractive at all the tested sites, supporting its status as a key pheromone component of L subelongatus, whereas （S）-（＋）-ipsdienol was inactive alone. Adding （S）-（＋）-ipsdienol to （S）-（-）-ipsenol did not have any effect on the trap catches from some populations in Inner Mongolia. However, （S）-（＋）-ipsdienol showed a strong synergistic effect on （S）-（-）- ipsenol from several populations in Jilin and Liaoning Provinces, and a weak synergistic effect from some transition populations in Heilongjiang Province. Furthermore, 27 mito- chondrial haplotypes were found among the 13 populations （intraspecific nucleotide di- vergence, 0.1%-1.1%）. Analyses of molecular variance and haplotype networks indicated that different geographic populations have developed some genetic variation but did not form completely independent groups. From an applied point of view, a universal synthetic binary blend ofracemic ipsenol and （S）-（＋）-ipsdienol might have a potential for monitoring or even mass-trapping of I. subelongatus across northeastern Chin

关键词： aggregation pheromone GC-EAD field trapping Ips subelongatus mtDNA-COI population divergence

A two-layer optimization model for high-speed railway line planning

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

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第12期12卷 902-912页

作者： Li WANG Li-min JIA Yong QIN Jie XU Wen-ting MO State key laboratory of Rail Traffic control and Safety Beijing Jiaotong University Beijing 100044 China

Line planning is the first important strategic element in the railway operation planning process,which will directly affect the successive planning to determine the efficiency of the whole railway system.A two-layer optimization model is proposed within a simulation framework to deal with the high-speed railway (HSR) line planning *** the model,the top layer aims at achieving an optimal stop-schedule set with the service frequencies,and is formulated as a nonlinear program,solved by genetic *** objective of top layer is tominimize the total operation cost and unserved passenger *** a specific stop-schedule,the bottom layer focuses on weighted passenger flow assignment,formulated as a mixed integer program with the objective of maximizing the served passenger volume andminimizing the total travel time for all *** case study on Taiwan HSR shows that the proposed two-layer model is better than the existing *** addition,this model is also illustrated with the beijing-Shanghai HSR in *** result shows that the two-layer optimization model can reduce computation complexity and that an optimal set of stop-schedules can always be generated with less calculation time.

关键词： Line plan Stop-schedule Passenger assignment High-speed railway (HSR)

Microsatellites reveal the genetic structure of thelytokous strains of the migratory locust

在线全文

学校读者我要写书评

暂无评论

Insect Science 2007年第3期14卷 193-199页

作者： ZHAO-QIAN TENG LE KANG State key laboratory of Integrated Management of pest and Rodents Institute of Zoology Chinese Academy of Sciences Beijing China

This study reports on two parthenogenetic strains of the migratory locust Locusta migratoria. The offspring of thelytokou females had a single fragment per microsatellite loci. All offspring of the parthenogenetic F1 females were genetically identical. These results further confirmed that restitution of the sister products of early cleavage mitoses and cell fusion might be the most likely diploidization mechanisms in the thelytokous locusts. Polymerase chain reaction amplification results demonstrated that thelytoky in the locust was not induced by Wolbachia bacteria. Apart from the low fitness gained in thelytokous females, large populations with migration and losing heterozygosity may be other reasons why regular parthenogenesis has not evolved in the locust.

关键词： genetic structure Locusta migratoria microsatellites thelytokous parthenogenesis Wolbachia

On the placement of actuators and sensors for flexible structures with closely spaced modes

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7期53卷 1973-1982页

作者： LIU XiaoXiang1,2 & HU Jun1,2 1 beijing Institute of control Engineering, beijing 100190, China 2 State key laboratory of Science and Technology on Space Intelligent control, beijing 100190, China beijing Institute of control Engineering Beijing China State key laboratory of Science and Technology on Space Intelligent control Beijing China

This paper analyzed the fundamental limitations of previous work and developed a new method to optimally locate actuators and sensors for structures with close modes. Optimization criteria were defined based on the distinguishing modal controllability and observability measures of close modes. An appropriate genetic algorism was adopted as the optimization algorism. Solving the high order Lyapunov functions was avoided by means of the closed-form expressions for controllability and observability Grammians. Since structure with widely separated natural frequencies is approximately balanced, computational efficiency was improved by grouping close modes together and dealing with the resulting subsystems independently. Finally, the effectiveness and optimality of the novel placement scheme were verified on a model structure with close modes.

关键词： close modes controllability/observability sensor/actuator optimization criterion optimization algorithm

An equivalent ground thermal test method for single-phase fluid loop space radiator

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2015年第1期28卷 86-92页

作者： Ning Xianwen Wang Yuying Zhang Jiaxun Liu Dongxiao beijing key laboratory of Space Thermal control Technology Beijing Institute of Spacecraft System Engineering (ISSE)

Thermal vacuum test is widely used for the ground validation of spacecraft thermal control system. However, the conduction and convection can be simulated in normal ground pressure environment completely. By the employment of pumped fluid loops＇ thermal control technology on spacecraft, conduction and convection become the main heat transfer behavior between radiator and inside cabin. As long as the heat transfer behavior between radiator and outer space can be equivalently simulated in normal pressure, the thermal vacuum test can be substituted by the normal ground pressure thermal test. In this paper, an equivalent normal pressure thermal test method for the spacecraft single-phase fluid loop radiator is proposed. The heat radiation between radiator and outer space has been equivalently simulated by combination of a group of refrigerators and thermal electrical cooler（TEC） array. By adjusting the heat rejection of each device, the relationship between heat flux and surface temperature of the radiator can be maintained. To verify this method,a validating system has been built up and the experiments have been carried out. The results indicate that the proposed equivalent ground thermal test method can simulate the heat rejection performance of radiator correctly and the temperature error between in-orbit theory value and experiment result of the radiator is less than 0.5 C, except for the equipment startup period. This provides a potential method for the thermal test of space systems especially for extra-large spacecraft which employs single-phase fluid loop radiator as thermal control approach.

关键词： spacecraft rejection orbit conduction branch pumped employment convection outer correctly

Enhanced catalytic performance of Cu-and/or Mn-loaded Fe-Sep catalysts for the oxidation of CO and ethyl acetate

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2017年第10期25卷 1427-1434页

作者： Lisha Liu Yong Song Zhidan Fu Qing Ye Shuiyuan Cheng Tianfang Kang Hongxing Dai key laboratory of beijing on Regional Air Pollution control Department of Environmental Science Beijing University of Technology Beijing 100124 China beijing key laboratory for Green Catalysis and Separation Key Laboratory of Beijing on Regional Air Pollution Control Key Laboratory of Advanced Functional Materials Education Ministry of China Laboratory of Catalysis Chemistry and Nanoscience Department of Chemistry and Chemical Engineering College of Environmental and Energy Engineering Beijing University of Technology Beijing 100124 China

The Fe-modi fied sepiolite-supported Mn–Cu mixed oxide(Cux Mny/Fe-Sep) catalysts were prepared using the co-precipitation *** materials were characterized by means of the XRD,N_2 adsorption–desorption,XPS,H_2-TPR,and O_2-TPD techniques,and their catalytic activities for CO and ethyl acetate oxidation were *** results show that catalytic activities of the Cux Mny/Fe-Sep samples were higher than those of the Cu1/Fe-Sep and Mn2/Fe-Sep samples,and the Mn/Cu molar ratio had a distinct in fluence on catalytic activity of the *** the Cux Mny/Fe-Sep and Cu1Mn2/Sep samples,Cu1Mn2/Fe-Sep performed the best for CO and ethyl acetate oxidation,showing the highest reaction rate and the lowest T50 and T90 of 4.4×10^(-6) mmol·g-1·s-1,110,and 140 °C for CO oxidation,and 1.9×10^(-6) mmol·g-1·s-1,170,and210 °C for ethyl acetate oxidation,***,the Cu1Mn2/Fe-Sep sample possessed the best lowtemperature reducibility and the lowest temperature of oxygen desorption as well as the highest surface Mn^(4+)/Mn^(3+) and Cu^(2+)/CuO atomic *** is concluded that factors,such as the strong interaction between the Cu or Mn and the Fe-Sep support,good low-temperature reducibility,and good mobility of chemisorbed oxygen species,might account for the excellent catalytic activity of Cu1Mn2/Fe-Sep.

关键词： Fe-modified sepiolite Supported Mn–Cu mixed oxide Reducibility Strong metal-support interaction CO oxidation Ethyl acetate oxidation

A comprehensive classification method for VOC emission sources to tackle air pollution based on VOC species reactivity and emission amounts

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2018年第5期30卷 78-88页

作者： Guohao Li Wei Wei Xia Shao Lei Nie Hailin Wang Xiao Yan Rui Zhang Municipal Research Institute of Environmental Protection Beijing 100037China key laboratory of beijing on Regional Air Pollution control Beijing University of TechnologyBeijing 100124China key laboratory of beijing on VOC Pollution control Technology and Application of Urban Atmosphere Beijing 100037China

In China, volatile organic compound（VOC） control directives have been continuously released and implemented for important sources and regions to tackle air pollution. The corresponding control requirements were based on VOC emission amounts（EA）, but never considered the significant differentiation of VOC species in terms of atmospheric chemical reactivity. This will adversely influence the effect of VOC reduction on air quality improvement. Therefore,this study attempted to develop a comprehensive classification method for typical VOC sources in the beijing–Tianjin–Hebei region（BTH）, by combining the VOC emission amounts with the chemical reactivities of VOC species. Firstly, we obtained the VOC chemical profiles by measuring 5 key sources in the BTH region and referencing another 10 key sources, and estimated the ozone formation potential（OFP） per ton VOC emission for these sources by using the maximum incremental reactivity（MIR） index as the characteristic of source reactivity（SR）. Then, we applied the data normalization method to respectively convert EA and SR to normalized EA（NEA） and normalized SR（NSR） for various sources in the BTH ***, the control index（CI） was calculated, and these sources were further classified into four grades based on the normalized CI（NCI）. The study results showed that in the BTH region,furniture coating, automobile coating, and road vehicles are characterized by high NCI and need to be given more attention; however, the petro-chemical industry, which was designated as an important control source by air quality managers, has a lower NCI.

关键词： VOC Source chemical profile Source classification beijing-Tianjin-Hebei (BTH) region