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Numerical simulation of pedestrian flow past a circular obstruction

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Acta Mechanica Sinica 2011年第2期27卷 215-221页

作者： Yan-qun jiang Ru-Xun Liu Ya-Li Duan Department of Mathematics Southwest University of Science and Technology 621010 Mianyang China Department of Mathematics University of Science and Technology of China 230026 Hefei China

In this paper, a revisiting Hughes’ dynamic continuum model is used to investigate and predict the essential macroscopic characteristics of pedestrian flow, such as flow, density and average speed, in a two dimensional continuous walking facility scattered with a circular obstruction. It is assumed that pedestrians prefer to walk a path with the lowest instantaneous travel cost from origin to destination, under the consideration of the current traffic conditions and the tendency to avoid a high-density region and an obstruction. An algorithm for the pedestrian flow model is based on a cellcentered finite volume method for a scalar conservation law equation, a fast sweeping method for an Eikonal-type equation and a second-order TVD Runge-Kutta method for the time integration on unstructured meshes. Numerical results demonstrate the effectiveness of the algorithm. It is verified that density distribution of pedestrian flow is influenced by the position of the obstruction and the path-choice behavior of pedestrians.

关键词： Pedestrian flow · Continuum model ·Finite volume method · Unstructured meshes · Obstruction

Estimation of Land Production and Its Response to Cultivated Land Conversion in North China Plain

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Chinese Geographical Science 2011年第6期21卷 685-694页

作者： jiang qun＇ou DENG Xiangzheng ZHAN Jinyan HE Shujin Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Graduate University of Chinese Academy of Sciences Beijing 100049 China Center for Chinese Agricultural Policy Chinese Academy of Sciences Beo＇ing 100101 China State Key Laboratory of Water Environment Simulation School of Environment Beijing Normal University Beijing 100875 China

Food safety and its related influencing factors in China are the hot research topics currently,and cultivated land conversion is one of the significant factors influencing food safety in *** the North China Plain as the study area,this paper examines the changes of cultivated land area using satellite images,estimates land productivity from 1985 to 2005 using the model of Estimation System for Land Productivity(ESLP),and analyzes the impact of cultivated land conversion on the land *** with the grain yield data from statistical yearbooks,the results indicate that ESLP model is an effective tool for estimating land *** productivity in the North China Plain showed a slight decreasing trend from 1985 to 2005,spatially,increased from the north to the south gradu-ally,and the net changes varied in different *** land area recorded a marginal decrease of 8.0 × 105 ha,mainly converted to other land *** land conversion had more significant negative impacts on land produc-tion than land productivity *** production decreased by about 6.48 × 106 t caused by cultivated land conversion between 1985 and 2005,accounting for 91.9% of the total land production *** the land productivity increased in Anhui and jiangsu provinces,it can not offset the overall adverse effects caused by cultivated land ***,there are significant meanings to control the cultivated land conversion and improve the land pro-ductivity for ensuring the land production in the North China Plain.

关键词： land productivity land production cultivated land cultivated land conversion North China Plain

SCREEN:predicting single-cell gene expression perturbation responses via optimal transport

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Frontiers of Computer Science 2024年第3期18卷 255-257页

作者： Haixin WANG Yunhan WANG qun jiang Yan ZHANG Shengquan CHEN Cadre Medical Department The 1st Clinical CenterChinese PLA General HospitalBeijing 100853China School of Statistics Renmin University of ChinaBeijing 100872China Ministry of Education Key Laboratory of Bioinformatics Bioinformatics Division of BNRISTDepartment of AutomationTsinghua UniversityBeijing 100084China School of Mathematical Sciences and LPMC Nankai UniversityTianjin 300071China

1 Introduction Recent advances in single-cell RNA sequencing(scRNA-seq)have enabled the study of how individual cells respond to various external perturbations such as drug stimulation at gene expression level[1].Precisely inferring perturbation responses allows us to explore how and why individual tumor cells evade cancer treatment,greatly advancing personalized medicine research and deepening our understanding of biological mechanisms[2].However,considering the high costs of sequencing and the complexity of obtaining perturbed samples,utilizing computational methods to predict cellular responses to perturbations holds great potential[2].

关键词： stimulation perturbation deepening

Environmental cost and pollution risk caused by the industrial transfer in Qinghai Province

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Frontiers of Earth Science 2014年第3期8卷 362-374页

作者： qun'ou jiang Chengcai TANG Jinyan ZHAN Wei ZHANG Feng WU School of Soil and Water Conservation Beijing Forestry University Beijing 100038 China School of Tourism Management Beijing International Studies University Beijing 100024 China State Key Laboratory of Water Environment Simulation School of Environment Beijing Normal University Beijing 100875 China

With the rising pressure due to energy consumption and costs of environmental protection and recovery, industrial transfer from the eastern to central and western areas has surged in China. However, extremely fragile ecological conditions and severe water shortage are significant hurdles for industry development in Western China. Whether the vulnerable environment can bear the pollution caused by the transferred industry from Eastern China becomes a significant issue. This study firstly estimates energy and environmental costs in different areas of China, and assesses the necessity to upgrade the industrial structure of Qinghai Province. Then the emis- sions of waste water, waste gas, and smoke caused by transferred industries are calculated by Input-Output Model. On the basis of the effect analysis of waste emission on environment, pollution risks of Qinghai province are assessed. The results illustrate that the costs of environmental protection and recovery in China have a gradient distribution, of which the energy efficiency is Lower while environmental costs are higher in Western China. Industrial structure adjustment has different impacts on the pollution of different sectors. Although the development of machinery and equipment, hotels and catering services, and real estate, leasing, and business services has increased the emission of pollutants, it is offset by the decreasing emissions caused by other industries such as construction and metal products. Therefore, although economic development will increase environ- mental pollution, industrial adjustments can effectively decrease waste water and waste gas emissions to reduce the pollution risk. It should be noted that there are still tremendous challenges for industrial transfer in Qinghai Province to coordinate the environment and industry development.

关键词： environmental cost industrial transfer energy,pollution risk Qinghai

Non-isolated stacked bidirectional soft-switching DC-DC converter with PWM plus phase-shift control scheme

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Journal of Modern Power Systems and Clean Energy 2017年第4期5卷 631-641页

作者： Ye MEI qun jiang Heya YANG Wuhua LI Xiangning HE Shun LI College of Electrical Engineering Zhejiang UniversityHangzhou 310027China State Grid Zhejiang Electric Power Research Institute Hangzhou 310027China

In this paper, a non-isolated stacked bidirectional DC-DC converter with zero-voltage-switching(ZVS) is introduced for the high step-up/step-down conversion systems. The extremely narrow turn-on and/or turn-off duty cycle existing in the conventional bidirectional buck-boost converters can be extended due to the stacked module configuration for large voltage conversion ratio applications. Furthermore, the switch voltage stress is halved because of the series connection of half bridge modules. The PWM plus phase-shift control strategy is employed, where the duty cycle is adopted to regulate the voltages between the input and output sides and the phaseshift angle is applied to achieve the power flow *** decoupled control scheme can not only realize seamless bidirectional transition operation, but also achieve adaptive voltage balance for the power switches. In addition, ZVS soft-switching operation for all active switches is realized to minimize the switching losses. Finally, a prototype of 1 kW operating at 100 kHz is built and tested to demonstrate the effectiveness of the proposed converter and the control strategy.

关键词： Bidirectional DC-DC converter PWM plus phase-shift control(PPS) Zero voltage switching(ZVS) Large voltage conversion ratio Flexible power flow regulation

Bonding characteristics of the Al_2O_3-metal composite coating fabricated onto carbon steel by combustion synthesis

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International Journal of Minerals,Metallurgy and Materials 2014年第9期21卷 886-893页

作者： Xiao-feng Xue Ze-hua Wang Ze-hua Zhou Shao-qun jiang jiang-bo Cheng Chang-hao Wang Jia Shao College of Mechanics and Materials Hohai University

The fabrication of an alumina-metal composite coating onto a carbon steel substrate by using a self-propagating high-temperature synthesis technique was demonstrated. The effects of the type and thickness of the pre-coated layer on the binding structure and surface qual- ity of the coating were systematically investigated. The macrostructure, phase composition, and bonding interface between the coating and the substrate were investigated by scanning electronic microscopy （SEM）, X-ray diffraction （XRD）, and energy-dispersive X-ray spectrometry （EDS）. The diffraction patterns indicated that the coating essentially consisted of α-Al2O3, Fe（Cr）, and FeO-Al2O3. With an increase in the thickness of the pre-coated working layer, the coating became more smooth and compact. The transition layer played an important role in enhancing the binding between the coating and the substmte. When the pre-coated working layer was 10 mm and the pre-coated transition layer was 1 ram, a compact structure and metallurgical bonding with the substrate were obtained. Thermal shock test results indicated that the ceramic coating exhibited good thermal shock resistance when the sample was rapidly quenched from 800℃ to room temperature by plunging into water.

关键词： carbon steel combustion synthesis composite coatings phase composition morphology thermal shock resistance

Application of artificial neural network for switching loss modeling in power IGBTs

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Journal of Zhejiang University-Science C(Computers and Electronics) 2010年第6期11卷 435-443页

作者： Yan DENG Xiang-ning HE Jing ZHAO Yan XIONG Yan-qun SHEN Jian jiang School of Electrical Engineering Zhejiang University Hangzhou 310027 China

The modeling of switching loss in semiconductor power devices is important in practice for the prediction and evaluation of thermal safety and system *** simulation-based behavioral models and data processing-based empirical models are difficult and have limited *** the artificial neural network(ANN) algorithm has often been used for modeling, it has never been used for modeling insulated gate bipolar transistor(IGBT) transient *** this paper, we attempt to use the ANN method for this purpose, using a customized switching loss test *** compare its performance with two conventional curve-fitting models and verify the results by *** model is generally superior in calculation speed, accuracy, and data requirement, and is also able to be extended to loss modeling for all kinds of semiconductor power devices.

关键词： Insulated gate bipolar transistor(IGBT) Switching loss Modeling Artificial neural network(ANN)

Superinfective Hepatitis E Virus Infection Aggravates Hepatocytes Injury in Chronic Hepatitis B

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Current Medical Science 2019年第5期39卷 719-726页

作者： Semvua Bukheti Kilonzo Yong-Ii WANG qun-qun jiang Wen-yu WU Peng WANG Qin NING Mei-fang HAN Department and Institute of Infectious Disease Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430030China

Hepatitis E virus(HEV)infection is a major cause of morbidity in endemic *** consequences among chronic hepatitis B(CHB)patients have been *** aim of this study was to assess the impact of superinfective HEV infection(acute and past)on virological and clinical features of patients with CHB ***,biochemical,virological and immunological data of 153 CHB patients including 98 with hepatitis B virus(HBV)monoinfection and 55 with HBV-HEV superinfection with both HEV and HBV infection was retrospectively investigated and analyzed in this study conducted in Wuhan,*** overall anti-HEV IgG seroprevalence was found to be 35.9% in CHB ***-HEV superinfection patients showed significantly higher rate of complications(ascites,hepato-renal syndrome&encephalopathy)(all with P=0.04),cirrhosis(P<0.001)and acute-on-chronic liver failure(P<0.001)than HBV monoinfection *** also displayed elevated ALTs(P<0.001)and total serum bilirubin(P<0.001)with diminished albumin(P<0.001)and HBV viral load(P<0.001).Cytokines assay revealed increased expression of IL-6(P=0.02),IL-10(P=0.009)and TNF-α(P=0.003)in HBVHEV superinfection patients compared to HBV monoinfection *** study demonstrated that HEV superinfection in CHB patients was associated with progressive clinical manifestation,which is likely due to the enhanced expression of cytokines related with hepatocytes *** was also associated with repressed HBV replication,but the underlying mechanism requires further investigation.

关键词： hepatitis E hepatitis B superinfection liver failure replication

scEpiTools: a database to comprehensively interrogate analytic tools for single-cell epigenomic data

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Journal of Genetics and Genomics 2024年第4期51卷 462-465页

作者： Zijing Gao Xiaoyang Chen Zhen Li Xuejian Cui qun jiang Keyi Li Shengquan Chen Rui jiang Ministry of Education Key Laboratory of Bioinformatics Bioinformatics Division at the Beijing National Research Center for Information Science and TechnologyCenter for Synthetic and Systems BiologyDepartment of AutomationTsinghua UniversityBeijing 100084China School of Mathematical Sciences and LPMC Nankai UniversityTianjin 300071China

Recent advances in single-cell sequencing technologies provide significant implications for understanding cellular heterogeneity,developmental biology,and disease *** fully exploit the potential of these data,numerous tools have been proposed for upstream and downstream *** the the single-cell RNA sequencing(scRNA-seq)community,scRNA-tools(Zappia et al.,2018)was proposed to help researchers navigate the plethora of tools by *** its inception,scRNA-tools has been widely used and its updated version further reveals trends in the field with over 1000 collected tools(Zappia and Theis,2021),providing a valuable guidance in selecting tools for analyses.

关键词： analytic selecting Tools