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Electrical Measurement to Assess Hydration process and the porosity Formation

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Journal of Wuhan university of Technology(Materials science) 2008年第5期23卷 761-766页

作者：魏小胜 department of civil {2. Huazhong University of Science and Technology

The change of electrical resistivity with time at early ages was used to investigate the hydration process and the porosity development. porosity reduction process of cement-based materials hydration was developed by a proposed method. The porosity reduction is fast at the setting period. The results find that the pore discontinuity occurs faster at lower water/cement ratios than at higher water/cement ratios which is similar to the results of the percolation method.

关键词： electrical resistivity hydration setting time percolation

High Temperature sensitive Fiber Bragg Grating with polymer Jacket

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Chinese Journal of lasers 1999年第5期B8卷 3-5页

作者： GyAN Bai'ou GUO Zhuanyun liu Zhiguo DONG Xiaoyi(Institute of Modern Optics, Nankai university, Tianjin 300071, {2.)Hwayaw Tam(Electrical engineering department, the hong kong polytechnic university,hung Hom kowloon hong kong, {2.) Institute of Modern Optics Nankai UniversityTianjin 300071China Electrical engineering department The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina

It is demonstrated the high thermal sensitivity of fiber Bragg grating with polymer jacket. Twenty-three times enhanced sensitivity and over 41nm Bragg wavelength-tuning range have been obtained when the fiber grating is packaged with a special kind of polymer. This is the largest thermal sensitivity and largest temperature-tuned range ever demonstrated to our knowledge.

关键词： Fiber Bragg grating temperature sensitivity wavelength-tuning polymer jacketed fiber

Influence of Calcium sulfate state and Fineness of Cement on Hydration of portland Cements Using Electrical Measurement

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Journal of Wuhan university of Technology(Materials science) 2006年第4期21卷 141-145页

作者：魏小胜 department of civil {2. Huazhong University of Science and Technology Wuhan 430074 China

The influence of calcium sulfate state and fineness of cement on hydration of portland cement was studied using electrical resistivity measurement. The bulk resistivity curve of the paste from the abnormal cement mainly with hemihydrate had a characteristic abnormal peak and rapid increase in early period. The resistivity measurement technique can be used to discriminate abnormal setting. For normal cement with gypsum, the increase in fineness of the portland cement decreases the minimum resistivhy due to a higher ionic concentration and increases the 2. hour resistivity due to a reduction in macroscopic pore size. The setting time, compressive strength, pore structure of pastes made from different cements were carried out to compare the influence of water to cement ratio, calcium sulfate state and fineness. It is found that the electrical and mechanical properties are strongly affected by the initial porosity, the presence of hemihydrate or gypsum, and the fineness of cement.

关键词： false setting electrical resistivity fineness hydration

Reflections on the Mechanism of Calcium phosphate Nucleation on Titanium in simulated Body Fluids

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Journal of Materials science & Technology 2005年第5期21卷 613-617页

作者： F.T.Chengdepartment of Applied physics, the hong kong polytechnic university, {2., china department of Applied physics Hong Kong Polytechnic University Hong Kong Hong Kong

The results and main findings of studies reported in the literature in relation to the deposition of calcium phosphate on Ti in simulated body fluids are summarized. The effects of the surface hydroxyl groups and the sign of surface charge on the nucleation of calcium phosphate are reviewed. One major controversy among the conclusions of different studies is the order of adsorption of the calcium ions and the phosphate ions in the initial stage of immersion. A simple model based on the amphoteric nature of the hydroxyl groups on Ti is proposed in an attempt to delineate the nucleation process for calcium phosphate on Ti in simulated body fluids. HpO4^2. ions interact with the hydroxyl groups via ion exchange and/or electrostatic attraction, and Ca^2. ions, via electrostatic attraction only. There is no preferential order of adsorption. seemingly inconsistent results in different studies possibly arise from different prior treatments of the samples, which affect the adsorption properties.

关键词： Titanium Calcium phosphate simulated body fluid Hydroxyl group point of zero charge surface charge

surface Characterization of laser surface Melted NiTi shape Memory Alloy in Hanks' solution

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材料热处理学报 2004年第5B期25卷 988-991页

作者： CUIZhen-duo ZHUsheng-li MANHauchung yANGXian-jin schoolofMaterialsscienceandengineering TianjinUniversityTianjin300072China departmentoflndustrialandsystemsengineering TheHongKongPolytechnicUniversityHungHomKowloonHongKongChina

The surface of Ti-50.8Ni at% shape memory alloy was melted by an Nd-yAG laser. The Ti/Ni and Ti4+/Ti atomic concentration ratios at the surface were changed significantly. The Ni ion release rate of the laser melted surface was much lower than that of the mechanical polished samples. A calcium-phosphorous layer with high Ca/p ratio was detected after immersion in Hanks’ solution.

关键词：离子释放速率形状记忆合金激光表面熔解生物材料

Characteristics of vertical ozone distribution in the lower troposphere in the yangtze River Delta at lin'an in the spring of 2.01

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science china Earth sciences 2005年第9期48卷 1519-1528页

作者： ZHENG Xiangdong1, chan Chuenyu2. CUI hong2. QIN yu3, chan loyan2. ZHENG yongguang3 & lEE yusiang2.1. Chinese Academy of Meteorological sciences, Beijing 100081, china 2. department of civil and structural engineering, hong kong polytechnic university, hung Hom, hong kong, china 3. department of Atmospheric sciences, peking university, Beijing 100871, china 1. Chinese Academy of Meteorological sciences 100081 Beijing China 2. department of civil and structural {2. Hong Kong Polytechnic University Hung Hom Hong Kong China 3. department of Atmospheric sciences Peking University 100871 Beijing China

We analyzed vertical distributions of ozone (O3) in the lower troposphere (< 5 km above ground) at lin’an (119.75°E, 30.30°N), Zhejiang province using electrochemical concen- tration cell (ECC) ozonesonde data obta... 详细信息

We analyzed vertical distributions of ozone (O3) in the lower troposphere (lin’an (119.75°E, 30.30°N), Zhejiang province using electrochemical concen- tration cell (ECC) ozonesonde data obtained from February 2. to April 13, 2.01. The results showed that the vertical O3 distributions are controlled by metrological conditions and the char- acteristics of O3 profiles are related to those of wet bulb potential temperature and wind field. O3 below 2.km showed that the strongest variability and enhanced O3 mixing ratios were associated with easterly winds that blow pollutants from the upwind source region of the yangtze River Delta (yRD) region. Vertical O3 profiles below 5 km can be grouped into 5 categories: (1) peak mixing ratio type, (2. well-mixed type, (3) layered-structure type, (4) episodic pollution type and (5) alti- tudinal increasing type. Vertical distributions of O3 affected by regional transport of polluted air masses were investigated. Transport of polluted air from high latitudes of northern china, ac- companying subsiding motion of air and stagnant atmospheric conditions are important factors that lead to high mixing ratios of O3 at lin’an. The stagnant atmospheric conditions associated with a continental high pressure system and pollution plume transported from the yRD and cen- tral-eastern china also lead to regional accumulation of O3 and high O3 mixing ratio at lin’an. long-range transport of O3 and pollutants from the pearl River Delta in south china and in-situ O3 formation also resulted in elevated O3 mixing ratios at around 1 km altitudes and layered O3 distribution in the lower troposphere.

关键词： vertical ozone distribution, lower troposphere, yangtze River Delta, lin'an.

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 {2. 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

properties of Cementitious Rendering Mortar prepared with Recycled Fine Aggregates

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Journal of Wuhan university of Technology(Materials science) 2010年第6期25卷 1053-1056页

作者：潘智生 department of civil and structural {2. The Hong Kong Polytechnic University

The results of an experimental study on investigating the properties of cementitious rendering mortars prepared with a recycled fine aggregate（RA） were *** RA was obtained from a recycling plant in which mixed demolition wastes were processed by mechanical crushing,sieving and sorting *** series of rendering mortar mixes were prepared with a constant water/cement and a constant aggregate/cement ratios of 0.55 and 3 *** sand and natural crushed rock fine were originally used in the two series separately,and they were consistently replaced by 2.%,50%,75% and 100% by the recycled *** experimental results showed that mechanical properties,such as compressive strength,flexural strength and modulus of elasticity of the mortars prepared with the RA were lower than the mortars made with the natural ***,the bond strength at the interface between the mortar and masonry bricks determined by the Triplet test was found to be higher for the mortars prepared with the RA.

关键词： rendering mortar recycled fine aggregate triplet test mechanical properties

sTUDy ON CONTROllABIlITy AND OBsERVABIlITy FOR THIN plATE sysTEM WITH pARAMETER UNCERTAINTy

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Chinese Journal of Mechanical engineering 1998年第3期11卷 60-67页

作者： li yiyang Ren lihong Chen Guodong liang Tianpei department of Me{2.ical engineering, the hong kong polytechnic university, hong kong hong kong polytechnic Univ Hong Kong Hong Kong

The controllability and observability analysis of thin plate system with parameter uncertainty is presented using the degree of controllability/observability and the robustness index. It provides a guidance to the des... 详细信息

关键词： Degree of controllability/observability Robustness index Active vibration control