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Wave propagation and energy dissipation in viscoelastic granular media

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Journal of Central South University 2001年第3期13卷 185-188页

作者： SUN Ye-zhi 1, WU Ai-xiang 1, LI Jian-hua 1,2.(1. College of Resources, Environment and Civil engineering, Central South Unive rsity, Changsha 410083, China 2. The 5th building Company in Guangdong Province, Shaoguan 512.2., China) College of Resources Environment and Civil Engineering Central South University Changsha China The 5th building Company in Guangdong Province Shaoguan China

In terms of viscoelasticity, the relevant theory of wave i n granular media is analyzed in this paper. Under the conditions of slight deforma tion of granules, wave equation, complex number expressions of propagation vecto r and attenuation vector, attenuation coefficient expressions of longitudinal wa ve and transverse wave, etc, are analyzed and deduced. The expressions of attenu ation coefficients of viscoelastic longitudinal wave and transverse wave show th a t the attenuation of wave is related to frequency. The higher the frequency is, the more the attenuation is, which is tested by the laboratory experiment. In a ddi tion, the energy dissipation is related to the higher frequency wave that is abs orbed by granular media. The friction amongst granular media also increase the e nergy dissipation. During the flowing situation the expression of transmission f actor of energy shows that the granular density difference is the key factor whi ch leads to the attenuation of vibrating energy. This has been proved by the exp eriment results.

关键词： viscoelastic granular media wave motion energy dissipation flowing situation

Reaction Products of MgO and Microsilica Cementitious Materials at Different Temperatures

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Journal of Wuhan University of Technology(Materials Science) 2011年第4期26卷 745-748页

作者：韦江雄 School of Materials Science and engineering South China University of Technology

The paste was prepared by mixing MgO, microsilica and H2. in the presence of water reducer at different reaction ratios and temperatures, and characterized by XRD, DTA, TGA, IR, and solid-state 2.Si NMR. The experimental results showed that, besides Mg（OH）2. magnesium silicate hydrate （M-S-H） was formed at a low temperature such as 2. and 50 ℃. At a high temperature of 100 ℃, Mg（OH）2.can be further transformed into M-S-H completely, for instance, within ca. 1 month in an excess of microsilica. The average composition and structure of M-S-H was mainly related to the reaction mixture and curing temperature and was discussed in detail.

关键词： MgO microsilica magnesium silicate hydrate (M-S-H)

Magnetron sputtering synthesis of large area well-ordered boron nanowire arrays

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Science China(Physics,Mechanics & Astronomy) 2004年第4期47卷 403-415页

作者： CAO Limin1,2. ZHANG Ze2.& WANG Wenkui1,2.1. Key Laboratory of Metastable Materials Science and Technology and College of Materials Science and engineering, Yanshan University, Qinhuangdao 066004, China 2. Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China Key Laboratory of Metastable Materials Science and Technology and College of Materials Science and engineering Yanshan University Qinhuangdao China Institute of Physics Chinese Academy of Sciences Beijing China

One-dimensionally nanostructured materials, such as nanowires and nanotubes, are the smallest dimensional structures for efficient transport of electrons and excitons, and are therefore critical building blocks for nanoscale electronic and mechanical devices. In this paper, boron nanowires with uniform diameters from 2. to 80 nm were synthesized by radio-frequency magnetron sputtering of pure boron powder and B2.3 powder mixtures in argon atmosphere. The boron nanowires produced stand vertically on the substrate surface to form well-ordered arrays over large areas with self- organized arrangements without involvement of any template and patterned catalyst. The high-density boron nanowires are parallel to each other and well distributed, forming highly ordered and uniform arrays. A more interesting and unique feature of the boron nanowires is that most of their tips are flat rather than hemispherical in morphologies. Detailed studies on its structure and composition indicate that boron nanowires are amorphous. Boron nanowire appears as a new member in the family of one-dimensional nanostructures. Considering the unique properties of boron-rich solids and other nanostructures, it is reasonable to expect that the boron nanowires will display some exceptional and interesting properties. A vapor-cluster-solid (VCS) mechanism was proposed to explain the growth of boron nanowires based on our experimental observations.

关键词： boron nanowires, magnetron sputtering, arrays, self-assembly.

Effects of Water/Binder Ratio on the Properties of Engineered Cementitious Composites

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Journal of Wuhan University of Technology(Materials Science) 2010年第2期25卷 298-302页

作者：杨英姿 School of Civil engineering Harbin Institute of Technology China building Materials Academy

The effects of water/binder ratio （w/b） on the toughness behavior, compressive strength and flexural strength of engineered cementitious composites （ECC） were investigated. The w/b ratios of 0.2., 0.31, 0.33 and 0.37 were selected and the specimens were tested at the ages of 7 d and 2. d. The experimental results showed that there was a corresponding increase in first cracking strength, modulus of rupture, compressive strength and flexural strength with the decrease of w/b. Within the w/b range of 0.2.-0.37, higher w/b was found to have improved effects on deflection, strain hardening index and toughness index of ECC. In the permission of meeting the requirement of compressive strength grade, selecting higher w/b in mix design will help to obtain robust ECC.

关键词： engineered cementitious composites (ECC) toughness water/binder ratio compressive strength

Magnesia Modification of Alkali-Activated Slag Fly Ash Cement

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Journal of Wuhan University of Technology(Materials Science) 2011年第1期26卷 121-125页

作者：沈卫国 Key Laboratory of Silicate Materials Science and engineering of Ministry of Education Wuhan University of Technology School of Materials Science and engineering Wuhan University of Technology

A new type of magnesia modification alkali-activated cement was prepared, the strength, setting time, shrinkage ratio and cracking behavior, as well as the composition and structure of the hydration product were investigated. The results indicate that the setting time of this cement is similar to that of the ordinary commercial cements; its strength reaches the standard of 42.5 degree cement, its cracking resistance has been remarkably improved because of the micro-aggregate effect of fly ash and shrinkage compensating of magnesia.

关键词： alkali-activated cement crack magnesia volume stability hydration

building Distributed Web GIS: A Mobile Agent Based Approach

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Wuhan University Journal of Natural Sciences 2001年第Z1期6卷 474-481页

作者： jhguan@*** Guan Ji hong 1 , Zhou Shui geng 2., Bian Fu ling 3, Meng Ling kui 3 1. School of Computer, Wuhan University, Wuhan 430072. China 2. State Key Laboratory of Software engineering, Wuhan University, Wuhan 430072. Chin School of Computer Wuhan University Wuhan 430072 China

The diversity of GISs and the wide spread availability of WWW have led to an increasing amount of research on integrating a variety of heterogeneous and autonomous GISs in a cooperative environment to construct a new generation of GIS characterizing in open architecture, distributed computation, interoperability, and extensibility. Our on going research project MADGIS (Mobile Agent based Distributed Geographic Information System) is reported, in which we propose the architecture of MADGIS to meet the requirements of integrating distributed GIS applications under Internet environment. We first describe the architecture of MADGIS, and detailed discussions focusing on the structure of client site, server site and mobile agent in MADGIS. Then we explore key techniques for MADGIS implementation.

关键词： distributed GIS mobile agent architecture mobility interoperability

Intuitionistic fuzzy hierarchical clustering algorithms

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Journal of Systems engineering and Electronics 2009年第1期20卷 90-97页

作者： Xu Zeshui1,2.1. Coll. of Economics and Management, Southeast Univ., Nanjing 2.0096, P. R. China 2. Inst. of Sciences, PLA Univ. of Science and Technology, Nanjing 2.0007, P. R. China Coll. of Economics and Management Southeast Univ. Nanjing 210096 P. R. China Inst. of Sciences PLA Univ. of Science and Technology Nanjing 210007 P. R. China

Intuitionistic fuzzy set （IFS） is a set of 2.tuple arguments, each of which is characterized by a membership degree and a nonmembership degree. The generalized form of IFS is interval-valued intuitionistic fuzzy set （IVIFS）, whose components are intervals rather than exact numbers. IFSs and IVIFSs have been found to be very useful to describe vagueness and uncertainty. However, it seems that little attention has been focused on the clustering analysis of IFSs and IVIFSs. An intuitionistic fuzzy hierarchical algorithm is introduced for clustering IFSs, which is based on the traditional hierarchical clustering procedure, the intuitionistic fuzzy aggregation operator, and the basic distance measures between IFSs： the Hamming distance, normalized Hamming, weighted Hamming, the Euclidean distance, the normalized Euclidean distance, and the weighted Euclidean distance. Subsequently, the algorithm is extended for clustering IVIFSs. Finally the algorithm and its extended form are applied to the classifications of building materials and enterprises respectively.

关键词： intuitionistic fuzzy set interval-valued intuitionistic fuzzy set hierarchical clustering intuitionisticfuzzy aggregation operator distance measure.

Experimental study of human-induced effects on floor slab of an ancient Tibetan structure

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Earthquake engineering and engineering Vibration 2012年第4期11卷 513-523页

作者： Yang Na Guo Ting S.S. Law School of Civil engineering Beijing Jiaotong University Civil and Structural engineering Department Hong Kong Polytechnic University

With the opening of ancient Tibetan structures to visitors worldwide, human load has become the principal live load on these structures. This project studies the properties of the floor structure of an ancient Tibetan building and its behavior under human-induced load effects. Tests were conducted with static and dynamic crowd load, including stepping and jogging by people at a fixed position. The tests show that the floor structure does not behave as a continuous slab. It takes the load from local areas with minimal load transference properties. The acceleration response shows significant peaks when the footstep frequency is close to the natural frequency of the s~＇ucture, but the human jogging excitation frequency does not have any obvious effect on the structural response. The elastic modulus of the Agatu material is estimated to be close to zero from the measured natural frequency of the slab. The Agatu material is concluded to be a discrete compacted material with insignificant contribution to the structural rigidity of the floor slab.

关键词： ancient Tibetan structure crowd load static dynamic floor slab Agatu elastic modulus

Earthquake Disaster Management and Insurance

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地球科学进展 2004年第S1期19卷 1-8页

作者： TANG Ai-ping~1, WEN Ai-hua~2.1. School of Civil engineering, Harbin Institute of Technology, Harbin 150090, China 2. School of Science, Harbin Institute of Technology, Harbin 150090, China)

As one of the most powerful tools to reduce the earthquake loss, the Earthquake Disaster Management [EDM] and Insurance [EI] have been highlighted and have had a great progress in many countries in recent years. Earthquake disaster management includes a series of contents, such as earthquake hazard and risk analysis, vulnerability analysis of building and infrastructure, earthquake aware training, and building the emergency response system. EI, which has been included in EDM after this practice has been...

关键词： Earthquake risk analysis Disaster management Earthquake insurance GIS.