层间接触对环氧沥青混凝土复合道面结构性能的影响

为了探究环氧沥青混凝土加铺层这种快速、有效的机场道面修建技术,利用ANSYS有限元程序,基于足尺多板体系,考虑了结构层之间不同的接触状态以及旧道面板之间的传荷能力,对复合道面结构层间受力状态进行了分析,结果表明:旧水泥混凝土道面板与基础之间的接触状况对加铺层弯沉影响略大,环氧沥青混凝土与旧水泥混凝土道面板之间的接触状况对复合道面结构应力指标影响明显,增强加铺层界面粘结强度能够改善复合道面结构受力状态,因此,在进行加铺层设计时要考虑选取合理的层间接触状态。     

PCC路面沥青加铺层荷载应力影响因素正交分析

本文采用有限元方法,分析荷载作用下PCC路面沥青加铺层的力学性能。研究发现,荷载作用下接缝区沥青加铺层底的剪应力明显高于弯拉应力;并进一步采用正交设计法研究了沥青加铺层厚度、PCC路面接缝宽度等因素对沥青加铺层底最大剪应力的影响,确定了各影响因素的显著性水平,分析结果对实际工程应用具有一定的参考意义。     

不同碎石化效果下沥青加铺层应力有限元分析

为充分了解碎石化破碎效果对沥青加铺层应力的影响情况，本文运用ANSYS建立了有限元模型，对不同破碎效果下的沥青加铺层进行了对比分析，推荐了合理的碎石化层模量和厚度。     

不均匀飞机轮载作用下沥青道面结构力学响应

为了研究不均匀飞机轮载作用下沥青道面结构力学响应，基于机轮条纹状接触面积假设和轮胎花纹，确定了轮胎的竖向应力函数，再结合已有研究确定了轮胎的纵、横向接触应力，计算获得了A380-800,B747-400,B777-300ER三维非均布接触应力；基于三维有限元分析模型，得到飞机三维非均布轮载作用下的道面结构力学响应，并分析了三种机型的力学响应的差异。研究结果表明：在三维非均布荷载作用下沥青道面的力学响应大于在均布竖向荷载下的力学响应；荷载的不均匀性对于沥青道面力学响应的影响沿沥青道面面层向土基逐渐减小；在三维非均布荷载作用下，沥青道面的力学响应受飞机的最大滑行质量、起落架构型、胎压、机轮个数等因素影响；随着沥青混合料模量增大，各力学响应参数的变化率也逐渐减小。     

夹层防治反射裂缝效果的应力探析

采用三维有限元静力分析方法，计算分析了具有接缝的旧水泥混凝土路面上沥青加铺层在行车荷载和温度变化作用下应力的变化情况，从理论上深人研究了应力吸收夹层和加筋夹层在不同情况下防治反射裂缝的效果，提出了两种夹层的模量推荐取值．     

随机荷载作用下刚性路面动态响应研究

为了研究车辆随机荷载作用下刚性路面的动态响应,基于ANSYS软件,应用1/4车辆模型,得出其在路面不平度激励下的随机荷载,简化了荷载的求解,建立了路面三维有限元模型,讨论了在随机荷载作用下结构层参数对路面动位移幅值及面层层底拉应力幅值的影响规律。结果表明,面层厚度和土基模量对路面动位移幅值影响最大,当面层厚度超过30 cm、土基模量超过60 MPa时,继续增大以上结构层参数路面动位移幅值不再有明显减少;当土基模量小于60MPa继续减少时,要实现路面动位移幅值的不变,需要增加的面层厚度幅度逐渐变大;面层模量及厚度对面层层底拉应力幅值影响最大。     

基于OLSM的旧水泥混凝土路面加铺结构应力分析

针对开级配大粒径沥青碎石(OLSM)优良的抗变形能力,采用有限元法对基于OLSM的旧水泥混凝土路面加铺结构进行应力分析。结果表明:设置OLSM抗裂层后,在车辆作用,温度应力以及二者的耦合作用下,接缝处的最大主应力、等效应力和最大剪应力都有较大程度的减小。     

聚酯玻纤布防裂性能影响因素的灰熵分析

通过分析聚酯玻纤布变形能力、拉应力等参数的特点,结合工程实际采用Abaqus理论构建了防裂道路模型,分析了沥青层底剪应力与聚酯玻纤布模量、厚度、黏弹性之间的相互关系以及与面层模量、基层模量之间的变化规律。进而采用灰关联熵法分析沥青层底剪应力与聚酯玻纤布的厚度、模量、层间黏结系数、面层模量及基层模量的灰熵关联度,发现基层模量和层间黏结系数是影响防裂效果的重要因素,为沥青道路裂缝病害的防治提出了新的思路。     

旧水泥混凝土路面压浆稳板关键技术研究

旧水泥混凝土路面加铺沥青层是一种极为普遍的刚柔复合路面结构,如旧水泥混凝土路面脱空处治不当,将导致反射裂缝等病害过早出现于刚柔复合路面结构内。为降低水泥混凝土路面板脱空对路面结构路用性能造成的影响程度,在加铺沥青层前,为有效防治水泥混凝土板底脱空病害,可选取压浆技术进行施工。为此,该文结合具体工程案例,对旧水泥混凝土路面压浆稳板关键技术进行了探讨。     

粘贴GFRP的钢桥面铺装层的剪切性能

大跨径钢桥由于桥面板厚度薄,容易出现推移、开裂等诸多病害。在桥面钢板上粘贴一定厚度的玻璃钢（GFRP）薄板,形成复合铺装结构,以提高铺装层刚度,延长铺装层使用寿命。采用ANSYS有限元软件,计算分析复合铺装结构的层间剪切应力分布状况,研究GFRP薄板的模量等对铺装结构受力的影响。结果表明,粘贴不同模量GFRP后,铺装层的应力、应变均出现了不同程度的变化。铺装层与钢板粘结处剪应力为未粘贴GFRP的1．44倍;剪应变减小为0．11％。但粘贴GFRP后铺装层层间最大剪应力和剪应变均大于未粘贴GFRP的铺装层,实际工程中应注重提高沥青铺装层的高温抗变形性能。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.