基于伏安法润滑油总碱值测定技术的研究

介绍了润滑油总碱值的一种测定新技术——循环伏安法。研究表明，用该方法测定润滑油总碱值是可行的，具有测定结果准确、自动化程度高、操作简单、测定时间短等优点，适合进行现场润滑油测定。     

水分对高碱值硫化烷基酚钙结构和清净性的影响

采用傅立叶红外光谱仪，分析了水分对清净剂高碱值硫化烷基酚钙结构组成的影响；采用热管氧化试验法和曲轴箱模拟试验法，考察了高碱值硫化烷基酚钙在加水前后清净性能的变化；采用四球试验机和高频往复试验机，分析了水分对高碱值硫化烷基酚钙润滑性能的影响。结果表明，油中的水含量对高碱值硫化烷基酚钙的水解安定性能影响较大，并且随着水含量的增加，油品的清净性能和抗磨性能变差。     

波流环境中污染物混合的分析

本文根据垂向二维数值模型计算求解和分析了波流环境中的一维对流扩散方程中的混合系数。此二维数值模型采用非线性k-ε紊流模型封闭雷诺时均方程，应用VOF方法处理自由面。分析方法是用该二维模型计算波流环境中污染物瞬时源产生的浓度场，计算该浓度场的断面平均浓度，求此断面平均浓度的概率分布，由概率分布的方差随时间的导数得到一维对流扩散问题中的混合系数。通过算例分析，发现波流环境混合系数随着波浪周期和波 高的不同，可能大于纯流和纯波的混合系数之和，也可能比纯流情况下小；波周期与混合系数呈正比。且存在一个使混合系数最大的波高。     

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可燃气体在运输、储存、加工和使用过程中，因可燃气体泄漏而形成的气云爆炸事故，常常会造成巨大的人员伤亡和财产损失。研究气云爆炸的特性和威力，可防范事故，减小损失。中采用有限差分方法编制了求解可燃气云爆炸过程的定解方程的数值模拟程序。方程组中的源项由能量均匀加入法处理，爆炸场中的间断问题通过人工黏性模型处理。经开敞空间乙炔——空气气云爆炸实验结果检验，数值计算结果的偏差在13％以内。计算结果表明，气云半径越大，爆炸最大压力和压力增加速率越大；气云爆热越大，爆炸最大压力和压力增加速率越大。     

基于参考点的模糊知识表示

本文分析了模糊关系模型的知识表示途径，并由此提出基于参考点的模糊知识表示，分析了它与人类记忆经验性知识的相信性，并证明模糊关系模型能以任意精度逼近具有有限个极值点的有界连续函数。     

Use of the time constant to detect corrosion speed in reinforced concrete structures

The relatively simple to measure ‘time constant’ is presented as an index for characterizing the level of corrosion experienced by steel in concrete. This communication, largely in the form of a technical note, explicitly illustrates that the time constant determined from electrochemical testing has significant merit for monitoring corrosion of steel in concrete, and appears to be insensitive to the area of electrode being probed. In this work, the time constant, κ, is determined following a galvanostatic excitation signal, revealing a good correlation between the value of κ and corrosion status across specimens of widely varying geometry. Although this notion has been suggested in the past, this work presents both a survey and consolidated review to indicate the utility of the parameter as an index to corrosion rate on-site.     

A COUPLING MODEL OF WATER FLOWS AND GAS FLOWS IN EXHAUSTED GAS BUBBLE ON MISSILE LAUNCHED UNDERWATER

The gas and water flows during an underwater missile launch are numerically studied. For the gas flow, the explicit difference scheme of Non-oscillation and Non-free-parameter Dissipation (NND) is utilized to solve the Euler equations for compressible fluids in the body-fitted coordinates. For the water flow, the Hess-Smith method is employed to solve the Laplace equation for the velocity potential of irrotational water flows based on the potential theory and the boundary element method. The hybrid Eulerian-Lagrangian formulation for the free boundary conditions is used to compute the changes of the free surface of the exhausted gas bubble in time stepping. On the free surface of the exhausted gas bubble, the matched conditions of both the normal velocities and pressures are satisfied. From the numerical simulation, it is found that the exhausted gas bubble grows more rapidly in the axial direction than in the radial direction and the bubble will shrink at its "neck" finally. Numerical results of the movement of the shock wave and the distribution of the Mach number and the gas pressure within the bubble were presented, which reveals that at some time, the gas flow in the Laval nozzle is subsonic and the gas pressure in the nozzle is very high. Influences of various initial missile velocities and chamber total pressures and water depths on both the time interval when the gas flow in the nozzle is subsonic and the peak of the gas pressure at the nozzle end were discussed. It was suggested that a reasonable adjustment of the chamber total pressure can improve the performance of the engine during the underwater launch of missiles.     

Detection of acylated homoserine lactones in gram-negative proteolytic psychrotrophic bacteria isolated from cooled raw milk

Through a mechanism called quorum sensing, bacteria are able to express specific genes in response to population density. Cell-to-cell communication in bacteria is mediated by signal molecules such as acylated homoserine lactones (AHLs). This work aimed to detect AHL production in Gram-negative psychrotrophic bacteria isolated from raw milk. A total of 84.9% of the bacteria were identified as AHL producers eliciting a diversity of responses in the AHL-monitor systems. These results demonstrate that AHL-production is common among psychrotrophic bacteria isolated from milk, and indicate that quorum sensing may play an important role in the spoilage of this product.     

空间桁架结构拓扑优化设计的线性规划方法

本文以杆件内力为设计变量,构造了多工况作用下空间桁架结构拓扑优化的线性规划模型,考虑了应力和位移约束,能够避免奇异最优拓扑和不稳定结构的产生。     

过渡金属碳化物的催化研究进展

过渡金属碳化物作为一种催化新材料得到了人们广泛的关注,在催化加氢、脱氢、脱硫(HDS)、脱氮(HDN)和重整等方面,表现出优良的催化活性和选择性.综述了碳化钒、碳化钼、碳化钨、碳化铁、碳化钛等碳化物的催化性能和碳化物在各个反应中的催化机理的研究进展.