Vertical shaking table tests on the structure with viscoelastic multi-dimensional earthquake isolation and mitigation devices

The viscoelastic multi-dimensional earthquake isolation and mitigation device is a new kind of passive control device, which can perform its "name-giving" task of earthquake isolation and earthquake mitigation simultaneously. In order to quantify its vertical earthquake isolation and mitigation effect on structures, firstly, shaking table tests on steel frame structures with and without the devices were carried out; secondly, analysis on dynamic characteristics and dynamic responses of the structures was al...     

Mathematical models of grinding manufacture and tooth contact analysis of spherical gears

The spherical gear is a gear-driven mechanism with two degrees of freedom (DOF), which can transfer spatial motion and power. Grinding machining of the spherical gear is performed with a plate grinding wheel by using generating method, and based on mathematical model of the plate grinding wheel, the mathematical model of the spherical gear is set up. And then, the meshing model of a spherical gear pair is developed and the tooth contact analysis (TCA) of the spherical gear pairs is performed. After that, th...     

Discrimination for ablative control mechanism in solid-propellant rocket nozzle

The ablation in solid-propellant rocket nozzle is a coupling process resulted by chemistry, heat and mass transfer. Based on the heat and mass transfer theory, the aero-thermo-dynamic, and thermo-chemical kinetics, the thermal-chemical ablation model is established. Simulations are completed on the heat flow field and chemical ablation in the nozzle with different concentrations, frequency factors and activation energy of H2. The calculation results show that the concentration and the activation energy of H...     

Examining the use of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles to enhance the NH<Subscript>3</Subscript> sensitivity of polypyrrole films

Summary Polypyrrole (PPy) composite films with different contents of Fe₃O₄ were prepared by in-situ polymerization of pyrrole in aqueous solutions. The dependence of dc current changes on the response of the samples exposure to NH₃ vapor has been investigated. The results shows the composite films are more stable than the pristine ones after being exposed to NH₃ vapor. Meanwhile, the response time was reduced with increasing the Fe₃O₄ content in the films. The results might be originated from the structural changes in the PPy films caused by the addition of Fe₃O₄.     

Study on volume ratio and plasticizer screening of free coating membranes composed of ethyl cellulose and chitosan

The aim of this study was to optimize the formula of free blended coating membrane of ethyl cellulose (EC) and chitosan (CS), including their suitable ratio range and the best plasticizer used. The dry films were produced by a casting/solvent evaporation method, with different volume ratio of EC and CS solution plasticized by various plasticizers, respectively. The wet films were prepared by immersing dry films in pH 6.8 phosphate buffer saline (PBS) for 24 h. The promising ratio range of EC/CS was below 20/5 or 20/6 with various plasticizer, which was determined by comparing the viscosity of the blended solutions and the morphology of the blended films. The efficiency of plasticization was evaluated by measuring glass transition temperature (T_g). All the testing plasticizers have good compatibility with EC or CS and dibutyl phthalate (DBP) have the strongest efficiency inducing the lowest T_g (39.9°C) of the film. Mechanical properties were evaluated by the ratio of tensile strength (T) to elastic modulus (E). In the wet state, the films with DBP had the highest T/E value (1.2). The results of leaching of plasticizers also verified that DBP was the most stable plasticizer in the films. The release rates of tetramethylpyrazine phosphate (TMPP) through the pellets coated with the blended films of EC/CS (20 : 6 v/v) plasticized by various plasticizers showed that the more water‐soluble the plasticizer was, the more quickly TMPP dissolved from the coated pellets, which further indicated that the water‐insoluble plasticizers (such as DBP) could be more applicable to keep the sustained or controlled release property of the blended films in wet state. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1932–1939, 2006     

Computational fluid dynamics (CFD) modeling of spouted bed: Influence of frictional stress, maximum packing limit and coefficient of restitution of particles

Following the previous article [Du, W., Bao, X., Xu, J., Wei, W., 2006. Computational fluid dynamics (CFD) modeling of spouted bed: assessment of drag coefficient correlations. Chemical Engineering Science 61 (5), 1401-1420], this contribution describes the influences of the frictional stress, maximum packing limit and coefficient of restitution of particles on CFD simulation of spouted beds. Using the two-fluid method embedded in the commercial CFD simulation package Fluent 6.1, the spouting hydrodynamics of a cylindrical-conical spouted bed was simulated and verified with the experimental data of He et al. [He, Y.L., Lim, C.J., Grace, J.R., Zhu, J.X., Qin, S.Z., 1994a. Measurements of voidage profiles in spouted beds. Canadian Journal of Chemical Engineering 72 (4), 229-234; He, Y.L., Qin, S.Z., Lim, C.J., Grace, J.R., 1994b. Particle velocity profiles and solid flow patterns in spouted beds. Canadian Journal of Chemical Engineering 72(8), 561-568]. The results showed that, for coarse particles, the frictional stress is important only for the annulus computation and has no obvious effects on the hydrodynamics of the solids flow in the spout region. The specification of the maximum packing limit could significantly affect the properties of the pseudo-fluid phase of the particles by changing the radial distribution function. The strong dependence of the pseudo-fluid properties of the particle phase, such as pressure, bulk viscosity and shear viscosity, on the granular temperature accounts for the influence of the coefficient of restitution of particles on CFD modeling. The solids volume fraction at loose packing state is suitable for spouted bed simulations, and a pretest of the coefficient of restitution of particles must be conducted when no experimental datum is available.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

聚苯乙烯-铂络合物催化硅氢加成反应机理的研究

将巯甲基化交联聚苯乙烯－铂络合物微球用于催化苯乙烯与甲基二氯硅烷的加成反应，考察了用硅氢加成试剂处理催化剂的时间对其催化行为的影响。发现催化活性中心主要是Pt（Ⅱ），催化剂的后处理时间明显影响硅氢加成反应的诱导期和活性，并根据实验结果提出了可能的催化机理。     

Energetic surface heterogeneity of nanocrystalline TiO<Subscript>2</Subscript> films for dye-sensitized solar cells

Dye sensitized solar cells (DSSCs) have been receiving significant attention because they have many advantages compared to conventional organic solar cells. It has been known that the photovoltaic characteristics of DSSC are highly dependent on the adsorption properties of dyes on TiO₂ films. To analyze the surface heterogeneity of TiO₂ surfaces, single-phase anatase nanocrystallite titanium films were prepared by sol-gel method using the hydrolysis reaction of titanium tetraisopropoxide under acidic condition and characterized by XRD, FE-SEM and BET analysis. The adsorption energy distribution functions were calculated by the generalized nonlinear regularization method. It was found that the shape and the intensity of the adsorption energy distribution curve determined were highly related with the physical properties (i.e., geometrical heterogeneity) and chemical characteristics (i.e., energetic heterogeneity) of nanocrystalline TiO₂ for DSSC.     

畜禽精确饲喂控制系统的研究与实施

基于Win CE 6.0平台,开发一套精确饲喂控制系统实现对畜禽的精确饲喂。以每个舍为单元,采用实时监控管理形式。使用耳标对猪进行身份识别。通过人工智能和畜禽养殖专家的知识库,自动计算,鉴别不同时期的畜禽,以此给予不同的喂食量,不同的饲料。系统主要有识别模块,实时监测模块,数据处理模块,人工控制模块,系统参数设定模块等组成。系统较智能化,易操作,可靠性强,易升级,可辅助畜禽养殖场,实现优质高产高效的养殖目的。