检索结果-南通市图书馆

Dynamic damage and stress-strain relations of ultra-high performance cementitious composites subjected to repeated impact

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2010年第6期53卷 1520-1525页

作者： LAI JianZhong1 & SUN Wei2 1 Department of Materials science and Engineering,nanjing university of science and technology,nanjing 210094,china 2 College of Materials science and Engineering,Southeast university,nanjing 211189,china 1. Department of Materials science and Engineering Nanjing University of Science and Technology Nanjing 210094 China2. College of Materials Science and Engineering Southeast University Nanjing 211189 China

Ultra-high performance cementitious composites (UHpCC) were prepared by replacing 60% of cement with ultra-fine industrial waste *** dynamic damage and compressive stress-strain relations of UHpCC were studied using split Hopkinson pressure bar (SHpB).The damage of UHpCC subjected to repeated impact was measured by the ultrasonic pulse velocity *** show that the dynamic damage of UHpCC increases linearly with impact times and the abilities of repeated impact resistance of UHpCC are improved with increasing fiber volume *** stress waves on impact were recorded and the average stress,strain and strain rate of UHpCC were calculated based on the wave propagation *** effects of strain rate,fibers volume fraction and impact times on the stress-strain relations of UHpCC were *** show that the peak stress and elastic modulus decrease while the strain rate and peak strain increase gradually with increasing impact times.

关键词： ultra-high performance cementitious composites (UHpCC) split Hopkinson pressure bar (SHpB) repeated impact damage stress-strain

EXpLICIT SIMULATION ON THE TrACK AND INTENSITY OF TrOpICAL CYCLONE WINNIE (1997)

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2006年第6期18卷 736-741页

作者： ZHONG Zhong ZHANG Jirl-shan institute of Meteorology PLA University of Science and Technology Nanjing 211101 China nanjing Hydraulic research institute Nanjing 210029 China

An explicit simulation of the tropical cyclone Winnie （1997） was conducted by use of a triply-nested 3-D nonhydrostatic mesoscale model MM5, before and after its landfall. The simulated results show that the model can well reproduce the track of Winnie （1997） with a BOGUS storm-like vortex inserted in the large-scale first-guess field at the initial model time. The mean track error in a 6 h interval is 54.5 km, which is much less than that obtained with the operational prediction. Comparisons between simulation and observation near the landfall place show that the main temporal variation features of sea level pressure and surface wind speed can also be successfully captured. The characteristics of the eyewall, the spiral cloud band and the corresponding precipitation were disclosed, and the applications of the model outputs were also discussed.

关键词： tropical cyclone simulation track intensity,eyewall spiral cloud band storm surge

Large-Eddy Simulations of turbulent flows with lattice Boltzmann dynamics and dynamical system sub-grid models

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2009年第3期52卷 670-679页

作者： GUAN Hui1 & WU ChuiJie2 1 research Center for Fluid Dynamics, pla university of science and technology, nanjing 211101, china 2 School of Aeronautics and Astronautics, Dalian university of technology, Dalian 116024, china research Center for Fluid Dynamics PLA University of Science and Technology Nanjing 211101 China School of Aeronautics and Astronautics Dalian University of Technology Dalian 116024 China

In this paper, two sub-grid scale (SGS) models are introduced into the Lattice Boltzmann Method (LBM), i.e., the dynamics SGS model and the dynamical system SGS model, and applied to numerically solving three-dimensional high re turbulent cavity flows. results are compared with those obtained from the Smagorinsky model and direct numerical simulation for the same cases. It is shown that the method with LBM dynamics SGS model has advantages of fast computation speed, suitable to simulate high re turbulent flows. In addition, it can capture detailed fine structures of turbulent flow fields. The method with LBM dynamical system SGS model dose not contain any adjustable parameters, and can be used in simulations of various complicated turbulent flows to obtain correct information of sub-grid flow field, such as the backscatter of energy transportation between large and small scales. A new average method of eliminating the inherent unphysical oscillation of LBM is also given in the paper.

关键词： Large-Eddy Simulation Lattice Boltzmann Method dynamics sub-grid scale model dynamical system sub-grid scale model parallel computation

MASS　CONSErVATION　BEHAVIOr　OF　WAVE　EQUATION　MODEL　FOr　SOLVING　SHALLOW　WATEr　EQUATION

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 1995年第4期7卷 1-12页

作者： Wu Jian-kang(Huazhong university of science and technology,Wuhan 430074,p.r.china) Huazhong Univ of science and Technology Wuhan China

Wave equation model(WEM)first developed by Lynch and Gray [2]is one of accurate and effective numerical methods to resolve shallow water *** paper shows the numerical consistency of the second- order wave equation and the first- order continuity equation, analyzes the error between them. This paper also shows that the numerical friction factor τo appearing in wave equation is of key importance to the numerical solutions and mass conservation of wave equation *** calculations of M2 tidal waves in rectangular harbor and a quarter annular harbor are made to demonstrate that it is possible to find a proper numerical friction factor τowith which accurate solutions and satisfactory mass conservation can be achieved by wave equation model.

关键词： numerical calculation tidal waves harbor

The Class of the Generalized αk-Major Efficient Solutions for Multi-objective programming

在线全文

学校读者我要写书评

暂无评论

Journal of Systems science and Systems Engineering 2001年第4期13卷 439-442页

作者： XU Ze-shui institute of sciences, pla university of science and technology, nanjing 210016, Jiangsu, china institute of sciences PLA University of Science and TechnologyNanjing 210016 Jiangsu China

This paper proposes the concepts of generalized αk-major efficient solutions and generalized αk- major optimal solutions for multi-objective programming, and studies their some important properties.

关键词： multi-objective programming generalized αk-major efficient solutions generalized αk-major optima1 solutions

A Method for Generating Super Large Fractal Images Useful for Decoration Art

在线全文

学校读者我要写书评

暂无评论

Communications in Nonlinear science and Numerical Simulation 1996年第3期1卷 24-27页

作者： Huajie LIU Jun LUO(research Center for science & Society peking university, p.r.china)(Department of Computer science & technology, peking university, p.r.china) [b] research Center for science & Society peking university p.r. china [a] Department of Computer science & technology peking university p.r. china

Many authors have reported the techniques to iterate nonlinear equations oncomplex plane, but generally, the sise of image calculated by usual VGA style (640×480) istoo small to fit the needs for high quality publications or decorative patterus. We describea universal method for generating and storing (in *.GIF format) fractal forge large enoughas you need, such as an wie 5000×5000 256-color(25,000, 74 bytes 23.8MB), whichcan thoroughly display the intricate beauty of fractals.

关键词： super large fractal images iteration decoration art

A SEMI-CIrCLE THEOrEM FOr UNSTABLE pErTUrBATION IN TrOpICAL CYCLONE-SCALE VOrTICLES

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2009年第4期21卷 473-481页

作者： HUANG Hong ZHANG Ming XU Ming institute of Meteorology PLA University of Science and Technology Nanjing 211101 China Shanghai Typhoon institute China Meteorological Administration Shanghai 200030 China Laboratory of Typhoon Forecast Technique/CMA Shanghai 200030 China

In this paper, we discusses the spectrum distribution of baroclinic disturbances in tropical cyclone-scale vortices with the assumption that the basic flow does not vary with height. The semi-circle theorem for the unstable perturbation is obtained and the upper bound of growth rate can be estimated. The upper bound of instability growth rate increases with the increase of the maximum basic-state tangential wind speed, angular speed, inertial parameter, absolute vorticity, radial gradient of absolute vorticity and static stability. The upper bound of instability growth rate is greater for vortices of larger horizontal scale and smaller vertical scale and lower wave-number disturbances.

关键词： tropical cyclone-scale vortex spiral bands instability semi-circle theorem

A STUDY ON THE rELATION BETWEEN THE VArIATION OF THE prECIpITATION IN EASTErN JIANGHUAI WATErSHED AND SEDIMENT TrANSpOrT IN CHIHE rIVEr VALLEY

在线全文

学校读者我要写书评

暂无评论

Chinese Geographical science 2002年第1期12卷 44-49页

作者： ZHANG Jian chun, pENG pu zhuo(Department of Urban and resources sciences,nanjing university,nanjing 210093,p.r.china ) Department of Urban and resources sciences Nanjing University Nanjing P. R. China

rainfall resource is very important to the development of society and economy,especially to eastern Jianghuai watershed which is now facing serious challenge of water shortage. Based on the observational records covering the period from 1957 to 1999,the characteristics of precipitation changing over eastern JiangHuai watershed and its connection to sediment discharge in Chihe river valley were studied using tendency analysis and correlation analysis .results show that the rainfall in this area had a declining tendency in Spring at a rate of -21.2mm/10a, annual and Summer precipitation was increasing at the rate of 10.6mm/10a and 14.8mm/10a. The gray correlation analysis shows that sediment discharge correlates most closely with runoffs and the frequency of the rainstorm with a daily precipitation of 50-100mm, on the second place,with the rainfall and the frequency of the rainstorm of a daily precipitation no less than 100mm;and thirdly with the number of rainy days. In addition, the paper suggests the major countermeasures and methods for controlling of soil and water losses in this area.

关键词： eastern Jianghuai watershed Chihe river rainfall sediment discharge correlation grade

在线全文

学校读者我要写书评

暂无评论

咖啡因的科学共识

中国食品学报 2024年第6期24卷 498-504页

作者：中国食品科学技术学会北京100048

咖啡因是一种常见于咖啡、茶叶和可可等植物中的天然活性成分,作为功能添加成分已在国际食品领域广泛应用多年,适量摄入有助于健康人群提高注意力,促进运动能力,缓解疲劳。国内外相关食品安全监管机构一致认为,咖啡因虽在日常饮食中的... 详细信息

咖啡因是一种常见于咖啡、茶叶和可可等植物中的天然活性成分,作为功能添加成分已在国际食品领域广泛应用多年,适量摄入有助于健康人群提高注意力,促进运动能力,缓解疲劳。国内外相关食品安全监管机构一致认为,咖啡因虽在日常饮食中的摄入是安全的,但需关注个体差异、摄入量以及频率。许多国家和地区已对咖啡因在食品中的应用制定了严格的应用限量和标识规定。为进一步提升大众对咖啡因的科学认知,消除对咖啡因的偏见,推动咖啡因在相关食品产业的合理应用,中国食品科学技术学会组织食品科学、公共卫生、食品安全与食品营养等领域专家与相关产业界代表,通过现场咨询、文献检索、专题研讨等形式和方法,经广泛讨论形成咖啡因的科学共识,以推动咖啡因在我国的规范使用。

关键词：咖啡因健康益处摄入量应用管理