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XiaoMu: an AI-driven assistant for MOOCs

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Science China(Information Sciences) 2021年第6期64卷 222-224页

作者： Zhengyang SONG Jie TANG Tracy Xiao LIU Wenjiang ZHENG Lili WU wenzheng FENG Jing ZHANG Institute for Interdisciplinary Information Sciences Tsinghua University Department of Computer Science and Technology Tsinghua University School of Economics and Management Tsinghua University Center for Strategic Studies Chinese Academy of Engineering Information School Renmin University of China

Nowadays, massive open online courses(MOOCs), are attracting widespread interest as an alternative education model. Several MOOCs platforms, such as Coursera, edX,and Udacity have been built and they provide low-cost opportunities for anyone who needs to access a massive number of courses from the worldwide top universities. However, the learning completion rate of the learners via MOOCs is extremely low compared with that in real classroom ***, this study builds a system, called XiaoMu, to design intelligent intervention strategies for the learning process of learners and improve the learning efficiency through automatic analysis of courses and learners. We deployed our system on the website1), which is one of the largest MOOCs in China.

关键词： Information Systems and Communication Service

Pre-chamber turbulent jet ignition of methane/air mixtures with multiple orifices in a large bore constant volume chamber: effect of air-fuel equivalence ratio and pre-mixed pressure

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Frontiers in Energy 2019年第3期13卷 483-493页

作者： Xiang LI wenzheng ZHANG Zhong HUANG Dehao JU Li HUANG Mingzhi FENG Xingcai LU Zhen HUANG Key Laboratory of Power Machinery and Engineering Ministry of EducationShanghai Jiao Tong UniversityShanghai 200240China Shanghai Marine Diesel Engine Research Institute Shanghai 201108China

Liquefied natural gas (LNG), mainly composed of methane, is in progress to substitute diesel fuel in heavyduty marine engine for practical, economic, and environmental considerations. However, natural gas is relatively difficult to be ignited in a large bore combustion chamber. A combustion enhancement technique called prechamber turbulent jet ignition (TJI) can permit combustion and flame propagation in a largebore volume. To investigate the effect of air-fuel equivalence ratio and pre-mixed pressure on pre-chamber TJI of methane/air mixtures with multiple orifices in a large bore volume, experimental tests and computational simulations were implemented to study the discharge of hot turbulent jets from six orifices of the pre-chamber. Different initial pressures and air-fuel equivalence ratios were considered to analyze the characteristics of TJI. The asymmetry of the turbulent jet actuated from six different orifices were found due to the asymmetric orientation of the spark plug, resulting in the inhomogeneous distribution of combustion in the constant volume chamber, which should be considered seriously in the marine engine design. Besides,as the premixed pressure increases, it has more effect on the flame propagation and plays a more important role, as it further increases.

关键词： marine engine natural gas methane turbulent jet ignition (TJI) pre-chamber

A Real-time Cutting Model Based on Finite Element and Order Reduction

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Computer Systems Science & Engineering 2022年第10期43卷 1-15页

作者： Xiaorui Zhang wenzheng Zhang Wei Sun Hailun Wu Aiguo Song Sunil Kumar Jha Wuxi Research Institute Nanjing University of Information Science&TechnologyWuxi214100China Engineering Research Center of Digital Forensics Ministry of EducationJiangsu Engineering Center of Network MonitoringSchool of Computer and SoftwareNanjing University of Information Science&TechnologyNanjing210044China School of Automation Nanjing University of Information Science&TechnologyNanjing210044China State Key Laboratory of Bioelectronics Jiangsu Key Lab of Remote Measurement and ControlSchool of Instrument Science and EngineeringSoutheast UniversityNanjing210096China IT Fundamentals and Education Technologies Applications University of Information Technology and Management in RzeszowRzeszow Voivodeship100031Poland

Telemedicine plays an important role in Corona Virus Disease 2019(COVID-19).The virtual surgery simulation system,as a key component in telemedicine,requires to compute in ***,this paper proposes a realtime cutting model based on finite element and order reduction method,which improves the computational speed and ensure the real-time *** proposed model uses the finite element model to construct a deformation model of the virtual ***,a model order reduction method combining proper orthogonal decomposition and Galerkin projection is employed to reduce the amount of deformation *** addition,the cutting path is formed according to the collision intersection position of the surgical instrument and the lesion area of the virtual ***,the Bezier curve is adopted to draw the incision outline after the virtual lung has been ***,the simulation system is set up on the PHANTOM OMNI force haptic feedback device to realize the cutting simulation of the virtual *** results show that the proposed model can enhance the real-time performance of telemedicine,reduce the complexity of the cutting simulation and make the incision smoother and more natural.

关键词： Virtual surgery cutting model finite element model model order reduction Bezier curve

Study of generation characteristics of glow-type atmospheric-pressure plasma jet based on DC discharge in air

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Plasma Science and Technology 2019年第12期21卷 40-49页

作者： wenzheng LIU Qingtian ZHENG Mingchao HU Luxiang ZHAO Zhiyi LI School of Electrical Engineering Beijing Jiaotong UniversityBeijing 100044People's Republic of China

In order to form an atmospheric-pressure plasma jet without airflow, a needle–ring electrode structure is proposed in this paper. When heteropolar potentials are applied to a needle and a ring, a marked electric field strength enhancement around the needle’s pointed end has been found. When the same potential is applied to both the needle and the ring, the lateral electric field strength for the needle can be weakened. By using the above two methods, an increase of the difference between the pointed end electric field strength and the lateral one is achieved and stable plasma jets are formed. A symmetrical space electric field distribution is established at the pointed end of the needles when several sets of heteropolar needle–ring electrodes are uniformly arranged, which is conducive to forming a uniform array plasma jet. Under DC discharge conditions, a safe and stable plasma jet of high density and an array plasma jet are successfully achieved.

关键词： DC discharge space electric field atmospheric-pressure air plasma jet array jet

Characteristics of Climate Change in the Lake Basin Area of Gangcha County

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Computers, Materials & Continua 2022年第10期73卷 363-379页

作者： wenzheng Yu Aodi Fu Li Shao Haitao Liu Xin Yao Tianliang Chen Hanxiaoya Zhang School of Geographical Sciences Nanjing University of Information Science&TechnologyNanjing210044China School of Environmental Science&Engineering Nanjing University of Information Science&TechnologyNanjing210044China Faculty of Science The University of Auckland1010New Zealand

This paper mainly was based on the average temperature,precipitation,humidity,and wind direction of Gangcha county from 1960 to *** using wavelet analysis and Mann-Kendall(M-K)mutation analysis,specifically analyzed the climate change characteristics in the lake basin area of Gangcha *** result showed that the climatic change in the lake basin area of Gangcha county is *** average temperature,average minimum temperature,average maximum temperature,and evaporation showed an increasing *** the evaporation in the study area was higher than *** average relative humidity showed a decreasing *** the sunshine and the average wind speed percentage showed a significant decreasing *** the Morelet wavelet,The time series of annual mean temperature,annual evaporation and annual sunshine percentage all have quasi3a and quasi4A periods,and the annual mean precipitation has quasi2–3A,quasi2–5A and quasi2–6A periods,which appear in 1996–2005,1962–1978 and 1978–1996 *** mean annual relative humidity has obvious quasi2–7A and quasi3A time series,which appear from 1960 to 1996,1997 to 2005 and after 2008,*** annual mean wind speed has quasi3–4A and quasi5A time series characteristics,which appear in 1964–1967,1984–1995,after 2009 and 1971–1983,*** Mann-Kendall(M-K)mutation analysis,it is found that the mutations of evaporation and the average speed of wind are *** mutation of evaporation started in 2004,and the mutation of average started in 2003.

关键词： Climate change the qinghai lake Morelet wavelet Mann-Kendall test

A new model for Doppler shift of C-band echoes backscattered from sea surface

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Acta Oceanologica Sinica 2023年第6期42卷 100-111页

作者： Jianbo Cui Yunhua Wang Yanmin Zhang Huimin Li wenzheng Jiang Yushi Zhang Xin Li College of Information Science and Engineering Ocean University of ChinaQingdao 266100China Qingdao National Laboratory for Marine Science and Technology Qingdao 266237China School of Marine Sciences Nanjing University of Information Science and TechnologyNanjing 210044China First Institute of Oceanography Ministry of Natural ResourcesQingdao 266061China National Key Laboratory of Electromagnetic Environment/China Research Institute of Radiowave Propagation Qingdao 266107China

Within the framework of the two-scale scattering model,the Doppler shift of C-band radar return signals from the nonlinear sea surface are numerically *** an analytical approximation method,the Bragg resonance scattering method cannot accurately describe the backscattering field from sea ***,in the twoscale scattering model,more accurate scattering coefficient(the normalized radar cross section,NRCS)evaluated by the C-band dual-polarized(HH/VV)empirical geophysical model function(CSAR model)is employed to replace the traditional Bragg NRCS to weight the Doppler *** numerical results indicate that there are obvious differences between the Doppler shift weighted by the CSAR NRCS and that weighted by the traditional Bragg *** hydrodynamic modulation of the large-scale waves is one of the important factors that affect the difference between the Doppler shift predicted in upwind and downwind *** the relaxation rate in the hydrodynamic modulation is set to be the angular frequency of the dominant water waves,the Doppler shift predicted by the numerical method can fit the results of the empirical model(C-band empirical geophysical model function,CDOP)well at moderate wind *** low wind condition,the comparison shows that the empirical CDOP model appears to overestimate the Doppler *** order to facilitate the application,at the end of this paper a semi-empirical CSAR-DOP model,which is a polynomial fitting formula,is developed for evaluating the Doppler shift of C-band signals from time varying sea surface.

关键词： Doppler shift microwave scattering numerical simulation

Assessment of popular techniques for co-processing municipal solid waste in Chinese cement kilns

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Frontiers of Environmental Science & Engineering 2022年第4期16卷 139-151页

作者： Hua Long Yang Liao Changhao Cui Meijia Liu Zeiwei Liu Li Li wenzheng Hu Dahai Yan State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 100012China College of Chemistry and Materials Science Sichuan Normal UniversityChengdu 610068China Zibo Environmental Pollution Prevention and Control Center Zibo 255000China

Cement kiln co-processing techniques have been developed in the past 20 years in China,and more than 60 factories now use fermentation,screening,and gasification pre-treatment techniques to coprocess municipal solid waste(MSW).There three complete MSW pre-treatment techniques,coprocessing procedures,and environmental risk assessments have been described in few *** this study,we assessed the effectiveness of each *** results suggested that the pollutant content released by each pre-treatment technology was lower than the emission *** reveal the mechanisms of pollutant migration and enrichment,the substances in the kiln and kiln products are *** input of co-processing materials(Co-M)produced by fermentation caused formation of polychlorinated dibenzo-p-dioxins and dibenzoftiran(PCDD/Fs)in the bypass flue gas(By-gas)in excess of the regulatory *** Co-M input produced by the screening and gasifier technologies caused the total organic carbon(TOC)concentration to exceed the *** addition,the NOx,TOC,and PCDD/Fs in the By-gas exceeded the regulatory *** meal was the primary chlorine and heavy metals input stream,and clinker(CK)and cement kiln dust(CKD)accounted for>90%of the total chlorine output *** gas and CKD were the primary volatile heavy metal(Hg)output *** than 70%of the semi-volatile heavy metals(Cd,Pb,T1 and Se)distributed in hot raw meal and bypass cement kiln *** low-volatility heavy metals were concentrated in the *** results indicated that co-processing techniques used in China still require improvement.

关键词： Cement kiln Co-processing Environmental risk assessment By-pass system

Differential Tectonic Deformation of the Longmen Mountain Thrust Belt,Western Sichuan Basin,China

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Acta Geologica Sinica(English Edition) 2009年第1期83卷 158-169页

作者： TANG Liangjie YANG Keming JIN wenzheng WAN Guimei LüZhizhou YU Yixin State Key Laboratory of Petroleum Resource and Prospecting Beijing 102249 China Key Laboratory for Hydrocarbon Accumulation Mechanism China University of Petroleum Ministry of Education Beijing 102249 China Basin and Reservoir Research Center China University of Petroleum Beijing 102249 China Southwest Branch Company SINOPEC Chengdu Sichuan 610081 China

Field investigation and seismic section explanation showed that the Longmen Mountain Thrust Belt has obvious differential deformation： zonation, segmentation and stratification. Zonation means that, from NW to NE, the Longmen Mountain Thrust Belt can be divided into the Songpan- Garz~ Tectonic Belt, ductile deformation belt, base involved thrust belt, frontal fold-thrust belt, and foreland depression. Segmentation means that it can be divided into five segments from north to south： the northern segment, the Anxian Transfer Zone, the center segment, the Guanxian Transfer Zone and the southern segment. Stratification means that the detachment layers partition the structural styles in profile. The detachment layers in the Longmen Mountain Thrust Belt can be classified into three categories： the deep-level detachment layers, including the crust-mantle system detachment layer, intracrustal detachment layer, and Presinian system basal detachment layer; the middle-level detachment layers, including Cambrian-Ordovician detachment layer, Silurian detachment layer, etc.; and shallow-level detachment layers, including Upper Triassic Xujiahe Formation detachment layer and the Jurassic detachment layers. The multi-level detachment layers have a very important effect on the shaping and evolution of Longmen Mountain Thrust Belt.

关键词： differential deformation detachment layer segmentation stratification transfer zone,zonation Longmen Mountain Thrust Belt

Comparative Proteomic Analysis of Arabidopsis Mature Pollen and Germinated Pollen

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Journal of Integrative Plant Biology 2009年第5期51卷 438-455页

作者： Junjie Zou Lianfen Song wenzheng Zhang Yi Wang Songlin Ruan Wei-Hua Wu State Key Laboratory of Plant Physiology and Biochemistry College of Biological Sciences China Agricultural University Beijing 100193 China Institute of Biotechnology Hangzhou Academy of Agricultural Sciences Hangzhou 310024 China

Proteomic analysis was applied to generating the map of Arabidopsis mature pollen proteins and analyzing the differentially expressed proteins that are potentially involved in the regulation of Arabidopsis pollen germination. By applying 2-D electrophoresis and silver staining, we resolved 499 and 494 protein spots from protein samples extracted from pollen grains and pollen tubes, respectively. Using the matrix-assisted laser desorption ionization time-of-flight mass spectrometry method, we identified 189 distinct proteins from 213 protein spots expressed in mature pollen or pollen tubes, and 75 new identified proteins that had not been reported before in research into the Arabidopsis pollen proteome. Comparative analysis revealed that 40 protein spots exhibit reproducible significant changes between mature pollen and pollen tubes. And 21 proteins from 17 downregulated and six upregulated protein spots were identified. Functional category analysis indicated that these differentially expressed proteins mainly involved in signaling, cellular structure, transport, defense/stress responses, transcription, metabolism, and energy production. The patterns of changes at protein level suggested the important roles for energy metabolism-related proteins in pollen tube growth, accompanied by the activation of the stress response pathway and modifications to the cell wall.

关键词： 2D-polyacrylamide gel electrophoresis Arabidopsis thaliana matrix-assisted laser desorption ionization time-of-flight mass spectrometry pollen pollen tube proteome.