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Proactive planning of bandwidth resource using simulation-based what-if predictions for Web services in the cloud

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Frontiers of Computer Science 2021年第1期15卷 25-52页

作者： Jianpeng hu Linpeng huANG Tianqi SUN Ying FAN wenqiang hu Hao ZHONG Department of Computer Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China School of Electronic and Electrical Engineering Shanghai University of Engineering ScienceShanghai 201620China

Resource planning is becoming an increasingly important and timely problem for cloud *** more Web services are moved to the cloud,minimizing network usage is often a key driver of cost *** existing approaches focus on resources such as CPU,memory,and disk I/*** particular,CPU receives the most attention from researchers,but the bandwidth is somehow *** is challenging to predict the network throughput of modem Web services,due to the factors of diverse and complex response,evolving Web services,and complex network *** this paper,we propose a methodology of what-if analysis,named Log2Sim,to plan the bandwidth resource of Web ***2Sim uses a lightweight workload model to describe user behavior,an automated mining approach to obtain characteristics of workloads and responses from massive Web logs,and traffic-aware simulations to predict the impact on the bandwidth consumption and the response time in changing *** use a real-life Web system and a classic benchmark to evaluate Log2Sim in multiple *** evaluation result shows that Log2Sim has good performance in the prediction of bandwidth *** average relative error is 2%for the benchmark and 8% for the real-life *** for the response time,Log2Sim cannot produce accurate predictions for every single service request,but the simulation results always show similar trends on average response time with the increase of workloads in different changing *** can provide sufficient information for the system administrator in proactive bandwidth planning.

关键词： what-if analysis bandwidth management network simulation Web service log mining resource planning evolution OPNET

基于现代信息技术的编译技术课程教学实践与探索——以“教、学、练”三体合一为例

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现代信息科技 2024年第18期8卷 189-193,198页

作者：胡雯蔷石桂玲祝建华华中科技大学软件学院湖北武汉430074 华中科技大学计算机科学与技术学院湖北武汉430074

针对编译课程任务重、内容难、课时短的现状,基于头哥实践教学平台(EduCoder)提出了“教、学、练”三体合一的线上线下融合编译技术教学教改思路。结合线上线下融合教学的特点,设计了课程内容层次结构,采用实验和理论教学融合并行以及... 详细信息

针对编译课程任务重、内容难、课时短的现状,基于头哥实践教学平台(EduCoder)提出了“教、学、练”三体合一的线上线下融合编译技术教学教改思路。结合线上线下融合教学的特点,设计了课程内容层次结构,采用实验和理论教学融合并行以及“教、学、练”交叉的教学模式,开发了多层次的通关案例,提出了多维立体评价体系。该教学教改思路已经进行了应用实践,教学质量得到了显著提升。

关键词：编译技术 “教、学、练” 三体合一线上线下融合

Fabrication, mechanical properties, and tribological behaviors of Ti2AlC and Ti2AlSn0.2C solid solutions

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Journal of Advanced Ceramics 2017年第2期6卷 90-99页

作者： Leping CAI Zhenying huANG wenqiang hu Suming HAO Hongxiang ZHAI Yang ZHOU Centre of Materials Science and Engineering School of Mechanical and Electronic Control EngineeringBeijing Jiaotong University Beijing 100044 China Centre of Materials Science and Engineering School of Mechanical and Electronic Control EngineeringBeijing Jiaotong University Beijing 100044 ChinaKey Laboratory of Vehicle Advanced Manufacturing Measuring and Control Technology(Beijing Jiaotong University) Ministry of Education China

Highly pure and dense Ti2AlC and Ti2AlSn0.2C bulks were prepared by hot pressing with molar ratios of 1∶1.1∶0.9 and 1∶0.9∶0.2∶0.85,respectively,at 1450 ℃ for 30 min with 28 MPa in Ar *** phase compositions were investigated by X-ray diffraction (XRD);the surface morphology and topography of the crystal grains were also analyzed by scanning electron microscopy (SEM).The flexural strengths of Ti2AlC and Ti2AlSn0.2C have been measured as 430 and 410 MPa,*** Vickers hardness decreased slowly as the load *** tribological behavior was investigated by dry sliding a low-carbon steel under normal load of 20-80 N and sliding speed of 10-30 m/***2AlC bulk has a friction coefficient of 0.3-0.45 and a wear rate of (1.64-2.97)×10-6 mm3/(N·m),while Ti2AlSn0.2C bulk has a friction coefficient of 0.25-0.35 and a wear rate of (2.5-4.31)× 10-6 mm3/(N·m).The influences of Sn incorporation on the microstructure and properties of Ti2AlC have also been discussed.

关键词： Ti2AlC Ti2AlSn0.2C microstructure mechanical property tribological behavior

Ti2AlC triggered in-situ ultrafine TiC/Inconel 718 composites:Microstructure and enhanced properties

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Journal of Materials Science & Technology 2020年第16期47卷 70-78页

作者： wenqiang hu Zhenying huang Qun Yu Yuanbo Wang Yidan Jiao Cong Lei Leping Cai Hongxiang Zhai Yang Zhou Institute of Materials Science and Engineering School of Mechanical and Electronic Control EngineeringBeijing Jiaotong UniversityBeijing100044China Key Laboratory of Vehicle Advanced Manufacturing Measuring and Control Technology(Beijing Jiaotong University)Ministry of EducationBeijing100044China

In situ ultrafine TiC dispersion reinforced Inconel 718 alloy with enhanced mechanical properties was fabricated by the technique of reactive hot-press sintering Ti2AlC and In718 *** effect of Ti2AlC precursor additions(5 vol.%,10 vol.%,15 vol.%)on microstructure and mechanical properties of TiC/In718 composites were investigated.A relationship of microstructural characteristics,room and elevated temperature mechanical performance,and underlying strengthening mechanisms were *** results show that initial Ti2AlC precursor transformed completely into ultrafine TiC particulate(~230 nm)and distributed uniformly in the matrix after sintering 5 and 10 vol.%Ti2AlC/***,TiC particulates tended to aggregate to stripes with the addition of Ti2AlC up to 15 vol.%,which,in adverse,weaken the properties of *** 5 vol.%Ti2AlC/In718 sample showed a higher tensile strength of 1404±13 MPa with a noticeable elongation of 9.8%at room temperature compared to the pure In718(ultimate tensile strength(UTS)=1310 MPa,elongation=21.5%).At 600℃,700℃,800℃and 900℃,tensile strength of the as-sintered 5 vol.%Ti2AlC/In718 composite was determined to be 1333±13 MPa,1010±10 MPa,685±25 MPa and 276±3 MPa,increased by 9.2%,14.6%,14.2%and 55%,respectively,compared with that of monolithic In718 *** excellent tensile properties of TiC/In718 composite can be ascribed to the combined mechanisms in term of increased dislocation density,dispersive Orowan and load transfer mechanisms.

关键词： Inconel 718 TiC reinforcement Ti2AlC High temperature properties Tensile strength

Heat-resistant Al_(2)O_(3) nanowire-polyetherimide separator for safer and faster lithium-ion batteries

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Journal of Materials Science & Technology 2023年第11期142卷 112-120页

作者： wenqiang hu Wenbin Fu Samik Jhulki Liang Chen Aashray Narla Zhijian Sun Fujia Wang Alexandre Magasinski Gleb Yushin School of Materials Science and Engineering Georgia Institute of TechnologyAtlantaGA 30332USA Institute of Materials Science and Engineering School of Mechanical and Electronic Control EngineeringBeijing Jiaotong UniversityBeijing 100044China Sila Nanotechnologies Inc AlamedaCA 94501USA School of Chemistry and Chemical Engineering Hunan Institute of Science and TechnologyYueyangHunan 414006China

Poor heat/flame-resistance of polyolefin(e.g.,polyethylene and polypropylene)separators and high flammability of organic electrolytes used in today’s lithium-ion batteries(LIBs)may trigger rare yet potentially catastrophic safety ***,we mitigate this challenge by developing a heat-resistant and flame-retardant porous composite membrane composed of polyetherimide(PEI)and Al_(2)O_(3) nanowires(NWs).The membranes are fabricated based on an industrially scalable non-solvent-induced phase separation process,which results in an intimately interconnected porous network of Al_(2)O_(3) NWs and *** produced composite membranes exhibit excellent flexibility,thermal stability,and ***,the composite membranes exhibit minimal thermal shrinkage and superior tensile strength(16 MPa)at temperatures as high as 200℃,significantly exceeding the performance of conventional polyolefin *** with commercial separators,their superior wettability and higher ionic conductivity(by up to 2.4 times)when filled with the same electrolyte,larger electrolyte uptake(-190 wt.%),as well as improved cycle and rate performance demonstrated in LiNiMnCoO_(2)(NCM)-based LIBs make them attractive choices for a variety of electrochemical energy storage devices.

关键词： Lithium-ion batteries Separators Al_(2)O_(3)NWs Polyetherimide Thermal resistance

Recent advances and challenges of nitrogen/nitrate electro catalytic reduction to ammonia synthesis

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Frontiers in Energy 2024年第2期18卷 128-140页

作者： Junwen CAO Yikun hu Yun ZHENG wenqiang ZHANG Bo YU Institute of Nuclear and New Energy Technology(INET) Collaborative Innovation Center of Advanced Nuclear Energy TechnologyTsinghua UniversityBeijing 100084China Department of Chemical Engineering University of WaterlooWaterlooOntario N2L 3G1Canada Institute of New Energy Materials and Engineering School of Materials Science and EngineeringFuzhou UniversityFuzhou 350108China

The Haber-Bosch process is the most widely used synthetic ammonia technology at *** its invention,it has provided an important guarantee for global food ***,the traditional Haber-Bosch ammonia synthesis process consumes a lot of energy and causes serious environmental *** the serious pressure of energy and environment,a green,clean,and sustainable ammonia synthesis route is urgently *** synthesis of ammonia is a green and mild new method for preparing ammonia,which can directly convert nitrogen or nitrate into ammonia using electricity driven by solar,wind,or water energy,without greenhouse gas and toxic gas ***,the basic mechanism of the nitrogen reduction reaction(NRR)to ammonia and nitrate reduction reaction(NO_(3)^(-))to ammonia were *** representative approaches and major technologies,such as lithium mediated electrolysis and solid oxide electrolysis cell(SOEC)electrolysis for NRR,high activity catalyst and advanced electrochemical device fabrication for(NO_(3)^(-))RR and electrochemical ammonia synthesis were *** on the above discussion and analysis,the main challenges and development directions for electrochemical ammonia synthesis were further proposed.

关键词： electrochemical ammonia synthesis nitrogen nitrate nitrogen reduction reaction(NRR)to ammonia nitrate reduction reaction(NO_(3)^(-))RR

Synthesized Optimization of Triangular Mesh

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武汉理工大学学报 2006年第S3期28卷 796-799页

作者： hu wenqiang YANG Wenyu School of software Engineering,huazhong University of Science and Technology,Wuhan 430074,China. School of software Engineering Huazhong University of Science and TechnologyWuhan 430074China

Triangular mesh is often used to describe geometric object as computed model in digital manufacture,thus the mesh model with both uniform triangular shape and excellent geometric shape is *** in fact,the optimization of triangu- lar shape often is contrary with that of geometric *** this paper,one synthesized optimizing algorithm is presented through subdividing triangles to achieve the trade-off solution between the geometric and triangular shape optimization of mesh *** result mesh with uniform triangular shape and excellent topology are obtained.

关键词： mesh optimization subdivision algorithm synthesized optimization

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负荷虚拟同步机及其低电压故障穿越控制

电力系统自动化 2018年第9期42卷 100-107页

作者：胡文强吴在军窦晓波胡敏强东南大学电气工程学院江苏省南京市210096

负荷虚拟同步机(LVSM)是一种电网友好型负荷并网接口,但其本身不具备低电压穿越能力。为此,文中提出一种适应电网对称与不对称故障的LVSM低电压穿越控制方法。首先,提出LVSM的统一拓扑及其基本控制策略。在基本控制策略的基础上增加电... 详细信息

负荷虚拟同步机(LVSM)是一种电网友好型负荷并网接口,但其本身不具备低电压穿越能力。为此,文中提出一种适应电网对称与不对称故障的LVSM低电压穿越控制方法。首先,提出LVSM的统一拓扑及其基本控制策略。在基本控制策略的基础上增加电网电压正序分量提取、低电压穿越检测、功率指令变更策略、故障期间使能的负序电流抑制、故障期间电流环输入限幅5个环节,实现电网故障短时间内LVSM不脱网、负荷稳定运行,并最大限度地为电网提供无功支撑。由于LVSM在故障期间保持惯性功率控制,故障结束后功率振荡平滑且有惯性,可有效减轻对电网的暂态冲击。硬件在环实验验证了所提低电压穿越控制方法的有效性。

关键词：负荷虚拟同步机低电压穿越无功支撑惯性支撑

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大采高综采工作面重装备单通道搬家技术

中国煤炭 2009年第7期35卷 53-55页

作者：胡文强山西焦煤西山煤电股份有限公司山西省太原市030053

针对斜沟煤矿8号煤层综采工作面采高大、装备重,搬迁困难的问题,分析了现有搬家技术的优缺点,提出了单通道搬家技术,介绍了大采高综采工作面重装备单通道回撤系统、大采高综采工作面重装备调车硐室安装系统,以及实施效果和应用前景。

关键词：综采工作面重装备单通道搬家