Comparative analysis on performance of vertical drain improved clay deposit under vacuum or surcharge loading

This paper presents two well-instrumented large-scale field tests of PVD-improved soft soil with vacuum and surcharge preloading, respectively. The two large-scale field tests were conducted adjacent to each other with the same preload. A comparative analysis was performed to investigate the performance of subsoil (i.e., the ground settlement, the layered settlement, the lateral displacement of subsoil and pore water pressure) under vacuum preloading and equivalent surcharge preloading. Some design methods were verified based on the field data. Cone Penetration Tests (CPT) and Vane Shear Tests (VST) were conducted to assess the improvement effects on subsoil after preloading. The results showed that as compared with surcharge preloading, vacuum preloading mitigated the differential settlement of the ground. The vacuum pressure transmitted into the soil with a minor loss through the PVD length. From a practical point of view, the improvement effects by vacuum preloading and surcharge preloading were similar in terms of influence depth and soil strength based on the in-situ tests.     

Perspectives of atmospheric reference leaks calibration by gravimetric method

The measurement of freon (mainly R134a) leaks is an important task of metrology. The paper deals with the study of the possibilities of improvement of gravimetric traceability method for the permeation secondary standards of atmospheric freon leaks. Their leak rates are different under atmospheric and vacuum conditions; only the first one is interesting for practical use. Moreover, the desirable steady state after changing the conditions is achieved only after certain relaxation time. This complicates the correction of the buoyancy influence, which causes the uncertainty increase. The leak rates of a typical secondary standard of this kind under atmospheric and vacuum conditions are compared, the needed relaxation times searched and some possibilities of further improvement discussed.     

Tribochemical Surface Reaction and Lubricating Oil Film

A radioactive tracer technique was used to investigate a tribo-chemical surface reaction obtained by a thrust collar type friction Machine. Radioactive dibenzyl disulfide labeled with sulfur-35 was used as an additive. Steel and copper disks were used as friction specimens.

Radioactive copper sulfide on the friction surface was quantitatively measured with a G-M tube, and a kinetical analysis of the reaction was carried out.

The friction coefficient decreased linearly depending on the amount of surface produced on the friction surface. This dependency was accompanied by adsorption of dibenzyl disulfide, which made a more effective lubricating oil film and was enhanced by the sulfide on the friction surface.

The results of kinetical analysis were explained effectively by considering the oil film behavior related to the adsorptive action of the surface sulfide.     

In-Situ,On-Demand Lubrication System for Space Mechanisms

Many of today's spaceraft have long mission lifetimes. Whatever the lubrication method selected, the initial lubricant charge is required to last the entire mission. Fluid lubricant losses are mainly due to evaporation, tribo-degradation, and oil creep out of the tribological regions.

In the past, several techniques were developed to maintain the appropriate amount of oil in the system. They were based on oil reservoirs (cartridges, impregnated porous parts), barrier films, and labyrinth seals. Nevertheless, all these systems have had limited success or have not established a proven record for space missions.

The system reported here provides to the ball-race contact fresh lubricant in-situ and on demand when the ball bearing is close to failure. The lubricant is stored in a porous cartridge attached to the inner or the outer ring of a ball bearing. The oil is released by heating the cartridge to eject oil, taking advantage of the greater thermal expansion of the oil compared to the porous network. The heating may be activated by torque increases that signal the depletion of oil in the contact. The low surface tension of the oil compared to the ball bearing material is utilized and the close proximity of the cartridge to the moving balls allows the lubricant to reach the ball-race contacts. This oil re-supply system avoided a mechanism failure, reduced torque to an acceptable level, and extended the life of the component.     

改性道路沥青的研制

以锦西石化分公司生产的辽河减压渣油为基质沥青,SBS为改性剂,采用适当的助溶剂,试制SBS改性道路沥青。相容剂对改性沥青的针人度、低温延度、软化点均有较大影响,选择合适的助溶剂添加粮是非常必要的。     

高速钢表面硬质合金覆层的组织及性能

通过热喷涂-真空粉末烧结的方法在高速钢表面制备硬质合金覆层，分析了硬质合金覆层组织和界面结构的特点、测试了硬质合金覆层的结合强度、硬度和耐磨性。结果表明，热喷涂后经过1200℃烧结，获得1—3mm厚度的硬质合金覆层，结合强度达到450MPa，硬度达到85HRA，具有较高的耐磨性能。     

多晶硅的真空感应熔炼及定向凝固研究

以工业硅为原料进行了多晶硅的真空感应熔炼及定向凝固研究，用自行设计的真空定向凝固设备制备了多晶硅铸锭。金相显微镜观察显示铸锭的显微组织为粗大的柱状晶，经电感耦合等离子体发射光谱仪分析，其纯度由99．50％提高到99．86％，各种杂质含量都有所减少。     

真空渗流法制备泡沫铝及其动态力学性能的研究

以真空渗流法制备陶瓷中空球泡沫铝,研究了应变率对吸能量和吸能效率的影响、相对密度对屈服强度的影响,并与普通泡沫铝进行比较。结果表明,工艺简单可行,所制备的泡沫铝的动态压缩应力-应变曲线只有弹性变形区和塑性变形区;随应变率的增大,屈服强度和吸能效率变化规律不明显,吸能量增大;随相对密度的增大,屈服强度增大,吸能量增大,吸能效率也增大;动态压缩时两种泡沫铝的吸能效率均较高,最大吸能效率大于0.9,是良好的吸能材料。     

护色工艺对真空油炸脱水马铃薯片品质的影响

采用真空油炸前预处理技术，研究了护色工艺对真空油炸马铃薯片品质的影响。结果表明，马铃薯片经过第四组护色液配方（柠檬酸1‰，亚硫酸氢钠1‰，VC1．5‰）处理后，产品具有最佳的感官品质和色泽值，而且对其水分含量、水分活度和脂肪含量均无显著性影响。     

真空干燥设计方案的模糊综合评价

构建了真空干燥模糊综合评价指标体系，运用综合评价法和模糊数学的相关理论建立了模糊综合评价模型，通过对300t／d玉米真空低温连续干燥具体案例的评价，为真空干燥在设计过程中选择最佳的方案提供了理论依据。