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Sensor Configuration and Test for Fault Diagnoses of Subway Braking System Based on Signed Digraph Method

Chinese Journal of Mechanical Engineering 2014年第3期27卷 475-482页

作者： ZUO Jianyong CHEN Zhongkai Institute of Railway and urban Mass Transit Tongji University

Fault diagnosis of various systems on rolling stock has drawn the attention of many researchers. However, obtaining an optimized sensor set of these systems, which is a prerequisite for fault diagnosis, remains a major challenge. Available literature suggests that the configuration of sensors in these systems is presently dependent on the knowledge and engineering experiences of designers, which may lead to insufficient or redundant development of various sensors. In this paper, the optimization of sensor sets is addressed by using the signed digraph （SDG） method. The method is modified for use in braking systems by the introduction of an effect-function method to replace the traditional quantitative methods. Two criteria are adopted to evaluate the capability of the sensor sets, namely, observability and resolution. The sensors configuration method of braking system is proposed. It consists of generating bipartite graphs from SDG models and then solving the set cover problem using a greedy algorithm. To demonstrate the improvement, the sensor configuration of the HP2008 braking system is investigated and fault diagnosis on a test bench is performed. The test results show that SDG algorithm can improve single-fault resolution from 6 faults to 10 faults, and with additional four brake cylinder pressure （BCP） sensors it can cover up to 67 double faults which were not considered by traditional fault diagnosis system. SDG methods are suitable for reducing redundant sensors and that the sensor sets thereby obtained are capable of detecting typical faults, such as the failure of a release valve. This study investigates the formal extension of the SDG method to the sensor configuration of braking system, as well as the adaptation supported by the effect-function method.

关键词： fault diagnosis subway braking system signed directed graph sensor set optimization.

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Energy Storage Performance of a PCM in the Solar Storage Tank

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Journal of Thermal Science 2019年第2期28卷 195-203页

作者： MAO Qianjun CHEN Hongzhang YANG Yizhi School of urban Construction Wuhan University of Science and Technology

High-temperature solar thermal power station with solar energy storage is one of the effective ways to solve energy shortage and environmental pollution. The heat storage characteristics of phase change materials in solar energy storage tanks directly affect the performance of the system and its future promotion and utilization. Based on the knowledge of heat transfer, fluid mechanics and engineering thermodynamics, this paper uses MATLAB software to compile the dynamic heat storage characteristics calculation program of phase change materials in energy storage tanks, and verify the results. This paper analyzes the phase change heat storage process with three PCM initial temperatures and three HTF speeds. The results show that when the initial temperature of the PCM changes from 185°C to 210°C, the latent heat storage heat increases by 21.8%, and the total heat storage decreases. Increasing the HTF speed from 1.8 m/s to 2.2 m/s, the melting time was reduced from 414 minutes to 390 minutes, and the total heat storage and sensible heat storage were also increased. The results also show that changing the initial temperature of the PCM and the flow rate of the HTF will change the thermal storage performance of the system. The research has certain reference significance for mastering the basic principle of high temperature solar thermal power generation system and promoting the application of the system.

关键词： solar phase change materials energy storage performance sensible heat latent heat

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Estimation method for a skip-stop operation strategy for urban rail transit in China

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Journal of Modern Transportation 2014年第3期22卷 174-182页

作者： Zhichao Cao Zhenzhou Yuan Dewei Li MOE Key Laboratory for urban Transportation Complex systems Theory and Technology Beijing Jiaotong University Beijing Jiaotong University

The skip-stop operation strategy （SOS） is rarely applied to Chinese urban rail transit networks because it is a simple scheme and a less universally popular transportation service. However, the SOS has performance advantages, in that the total trip time can be reduced depending on the number of skipped stations, crowds of passengers can be rapidly evacuated at congested stations in peak periods, and the cost to transit companies is reduced. There is a contradiction between reducing the trip time under the SOS and increasing the passengers＇ waiting times under an all-stop scheme. Given this situation, the three objectives of our study were to minimize the waiting and trip times of all passengers and the travel times of trains. A comprehensive estimation model is presented for the SOS. The mechanism through which the trip time for all passengers is affected by the SOS is analyzed in detail. A 0-I integer programming formulation is established for the three objectives, and is solved using a tabu search algorithm. Finally, an example is presented to demonstrate that the estimation method for the SOS is capable of optimizing the timetable and operation schemes for a Chinese urban rail transit network.

关键词： rail transit algorithm Skip-stop operation strategy network Integer programming Chinese urban Genetic

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A rapid modeling method for urban microscale meteorology and its applications

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Science China Earth Sciences 2023年第10期66卷 2224-2238页

作者： Xiaoran GUO Chao YAN Shiguang MIAO Institute of urban Meteorology China Meteorological AdministrationBeijing100089China Key Laboratory of urban Meteorology China Meteorological AdministrationBeijing100089China

This paper introduces a fast urban microscale meteorological model with a horizontal resolution of O(10)m,named urban(urban Rapid&Building-Aware Neighborhood),which is capable of rapid assessment of meteorological fields over key urban areas,including wind speed,air temperature,humidity and thermal comfort index,with the execution time less than10 minutes consuming 1 CPU *** uses a fast wind diagnostic method to construct three-dimensional(3-D)wind fields surrounding complex building clusters with their geometry resolved *** enhance the accuracy of wind reconstruction and the continuity of the initial wind field around irregular buildings,we propose a new parameterization method based on stream functions,which can accurately characterize the influences of complex urban building clusters on the three-dimensional wind *** model can provide various results for the meteorological service of large outdoor activities,including conventional meteorological elements(wind,temperature,humidity,radiation,etc.)and the Universal Thermal Comfort Index,which is derived from the relationship between physiological processes and environmental meteorological *** this paper,urban is applied to develop an automatic analysis and forecast system of microscale meteorological elements over the central Beijing region in summer during a large outdoor *** comparing with the half-hourly observations from three auto weather stations(AWSs)in the region,the root-mean-square errors(RMSEs)of the modeled 10-meter-height wind speed,2-meter-height air temperature and humidity are 0.98 m s^(-1),1.37℃and 7.37%,respectively.

关键词： urban microscale meteorology Wind diagnose Fast simulation Human comfort index Weather service

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An exclusion process with dynamic roadblocks

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Chinese Physics B 2016年第6期25卷 118-122页

作者：郭宁陈金邕胡茂彬姜锐 School of Engineering Science University of Science and Technology of China Hefei 230026 China MOE Key Laboratory for urban Transportation Complex systems Theory and Technology Beijing Jiaotong University Beijing 100044 China

We study an exclusion process with multiple dynamic *** roadblock can move diffusively forward or backward with different rates,as well as unbind from/rebind to a free *** Monte Carlo simulations,the two moving types are investigated in combination of roadblock *** case of only diffusive roadblocks shows an asymmetric current-density *** case of only long-range jumping roadblocks presents that flux decreases with increasing roadblock number.

关键词： exclusion process roadblocks diffusion unbinding/rebinding

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Survival analysis of car travel time near a bus stop in developing countries

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Science China(Technological Sciences) 2012年第8期55卷 2355-2361页

作者： YANG XiaoBao GAO ZiYou GUO HongWei HUAN Mei MOE Key Laboratory for urban Transportation Complex systems Theory and Technology Beijing Jiaotong UniversityBeijing 100044China Department of Transportation Engineering Beijing Institute of TechnologyBeijing 100081China

This paper presents an important investigation into car travel time affected by mixed traffic flow near a bus stop on the basis of survival analysis *** time data associated with mixed traffic characteristics near a bus stop were collected by video cameras.A hazard-based duration model was introduced to analyze the effects of mixed traffic flow on car travel *** results indicate that mixed traffic flow impacts car travel time *** the presence of bus berthing violation would delay car travel *** proposed model can be used to forecast temporal shifts in car travel time due to changes in mixed traffic *** influential factors related to mixed traffic flow should be given full consideration in the planning and designing of bus stops in developing countries.

关键词： survival analysis travel time duration model bus stop mixed traffic

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GPS/BDS/INS tightly coupled integration accuracy improvement using an improved adaptive interacting multiple model with classified measurement update

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Chinese Journal of Aeronautics 2018年第3期31卷 556-566页

作者： Houzeng HAN Jian WANG Mingyi DU Key Laboratory for urban Geomatics of National Administration of Surveying Mapping and Geoinformation School of Geomatics and urban Spatial Informatics Beijing University of Civil Engineering and Architecture

An Extended Kalman Filter（EKF） is commonly used to fuse raw Global Navigation Satellite System（GNSS） measurements and Inertial Navigation System（INS） derived measurements. However, the Conventional EKF（CEKF） suffers the problem for which the uncertainty of the statistical properties to dynamic and measurement models will degrade the *** this research, an Adaptive Interacting Multiple Model（AIMM） filter is developed to enhance performance. The soft-switching property of Interacting Multiple Model（IMM） algorithm allows the adaptation between two levels of process noise, namely lower and upper bounds of the process noise. In particular, the Sage adaptive filtering is applied to adapt the measurement covariance on line. In addition, a classified measurement update strategy is utilized, which updates the pseudorange and Doppler observations sequentially. A field experiment was conducted to validate the proposed algorithm, the pseudorange and Doppler observations from Global Positioning System（GPS） and Bei Dou Navigation Satellite System（BDS） were post-processed in differential *** results indicate that decimeter-level positioning accuracy is achievable with AIMM for GPS/INS and GPS/BDS/INS configurations, and the position accuracy is improved by 35.8%, 34.3% and 33.9% for north, east and height components, respectively, compared to the CEKF counterpartfor GPS/BDS/INS. Degraded performance for BDS/INS is obtained due to the lower precision of BDS pseudorange observations.

关键词： Adaptive filtering BeiDou navigation satellite system (BDS) Classified measurement update Global positioning system (GPS) Inertial navigation system (INS) Interacting multiple model Tightly coupled

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Extreme rain event highlights the lack of governance to face climate change in the Southeastern coast of Brazil

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Geography and Sustainability 2024年第1期5卷 29-32页

作者： M.L.Ferreira Postgraduate program in Architecture and urban Planning University of Varzea GrandeMT 78118-900Brazil

New rainfall records were registered in the southeastern region of Brazil during February *** amount of rain in the north coast region of the State of São Paulo was more than 650 mm in less than two *** and tragedies with a socioeconomically vulnerable population marked this climatic *** country has a regulatory system that suggests the elaboration and implementation of municipal public policies aimed at territorial organization,environmental conservation,and the prevention of disasters induced by natural *** addition,both federal and state funds earmarked for such hazard's prevention have been underutilized over the last *** addition to this current devastating climate episode,other events were registered in this decade,reinforcing that financial governance is a key challenge to face the climate crisis in *** predicted future extreme events in different regions of Brazil will require a different governance system to minimize social inequality,seek sustainable alternatives for urban environments and manage to adapt cities for the challenges posed by climate change.

关键词： Disaster risk Environmental public policies Public funds Territorial planning

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Growth and metal uptake of energy sugarcane (Saccharum spp.) in different metal mine tailings with soil amendments

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Journal of Environmental Sciences 2014年第5期26卷 1080-1089页

作者： Xin Zhang Yongguan Zhu Yuebin Zhang Yunxia Liu Shaochun Liu Jiawen Guo Rudan Li Songlin Wu Baodong Chen State key Laboratory of urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of Sciences Key Lab of urban Environment and Health Institute of Urban EnvironmentChinese Academy of Sciences Sugarcane Research Institute Yunnan Academy of Agricultural Sciences

A pot experiment was conducted to investigate the feasibility of growing energy sugarcane （Sac- charum spp.） in three different metal mine railings （Cu, Sn and Pb/Zn tailings） amended with uncontaminated soil at different mixing ratios. The results indicated that sugarcane was highly tolerant to tailing environments. Amendments of 20% soil to Sn tailings and 30% soil to Cu tailings could increase the biomass of cane-stem for use as the raw material for bioethanol production. Heavy metals were mostly retained in roots, which indicated that sugarcane was useful for the stabilization of the tailings. Bagasse and juice, as the most valuable parts to produce bioethanol, only accounted for 0.6%- 3% and 0.6%-7% of the total metal content. Our study supported the potential use of sugarcane for tailing phytostabilization and bioenergy production.

关键词： bioenergy crop sugarcane metal mine tailings phytoremediation

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Effect of Partial Replacement of Fly Ash by Decoration Waste Powder on the Fresh and Mechanical Properties of Geopolymer Masonry Mortar

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Journal of Wuhan University of Technology(Materials Science) 2024年第3期39卷 698-704页

作者：刘惠 ZHANG Ruidong 朱平华 WANG Xinjie CHEN Chunhong School of urban Construction Changzhou UniversityChangzhou 213164China

This study aims to investigate the feasibility of using decoration waste powder(DWP)as a partial replacement for fly ash(FA)in the preparation of geopolymer masonry mortar,and to examine the effect of different DWP replacement rates(0%-40%)on the fresh and mechanical properties of the *** results showed that each group of geopolymer masonry mortar exhibited excellent water retention performance,with a water retention rate of 100%,which was due to the unique geopolymer mortar system and high viscosity of the alkaline activator *** to the control group,the flowability of the mortar containing lower contents of DWP(10%and 20%)was ***,as the DWP replacement rate further increased,the flowability gradually *** DWP could absorb the free water in the reaction system of geopolymer mortar,thereby limiting the occurrence of geopolymerization *** incorporation of DWP in the mortar resulted in a decrease in compressive strength compared to the mortar without ***,even at a replacement rate of 40%,the compressive strength of the mortar still exceeded 15 MPa,which met the requirements of the masonry *** was feasible to use DWP in the geopolymer masonry *** the addition of DWP caused some performance loss,it did not affect its usability.

关键词： fly ash-based geopolymer decoration waste powder masonry mortar workability compressive strength

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