液压泵污染磨损的研究

本文评述了现有液压泵污染磨损理论,研究了污染物磨损性、颗粒尺寸及分布对液压泵污染磨损的影响。提出了泵的寿命决定于现场实际污染物的磨损性和泵内关键运动副动态间隙尺寸与污染颗粒尺寸的相对关系的污染磨损理论。建立了新的液压泵污染磨损模型,根据此模型可预测泵在实际工况下的寿命。     

Microwave pasteurization of metalworking fluids and lubricating oils

Microwave energy of 2450 MHz was examined as a method of pasteurizing infected lubricating oils and metalworking fluids. In the lubricating oil samples studied, a killing effect was seen at a lower than expected temperature (below 40°C). This was believed to be due to preferential microwave absorption by the aqueous microenvironments around the contaminant bacteria, causing localized high temperatures. When an alternating microwave exposure and cooling regime was employed, in which the localized heat was allowed to dissipate to the bulk oil, no significant change in numbers was seen.In the infected metalworking fluids, some reduction in microbial numbers was seen at low bulk temperature, with virtual sterility being achieved at higher temperatures. An alternating microwave exposure and cooling regime, in which the fluid temperature was kept below 45°C, showed no significant change in microbial numbers.     

基于磁电阻率法和频率域电磁法的地下水污染动态监测仿真

本文对磁电阻率法与频率域电磁法在地下水污染监测中的应用进行了理论研究.以污染物位于地表的均匀介质模型为例,根据污染物扩散的水文地质动态仿真结果,计算出与各监测时刻对应的地下水污染地电模型.通过各地电模型的二维磁电阻率法正演模拟结果以及一维频率域电磁法的反演结果,验证了这两种地球物理方法在地下水污染物运移监测中的有效性.     

基于声发射技术的绝缘子在线监测方法的研究

通过对绝缘子现行的污秽监测方法的研究分析,提出了基于声发射技术的绝缘子污秽放电在线监测方法,对电晕放电和污秽放电声发射信号进行了实验研究,并对两者放电声发射在波形相位与强度上的差别进行了分析比较,基本消除了电晕放电对污秽放电声发射信号的干扰,从而揭示了污秽放电的严重程度和声信号之间的关系,证明了声发射技术在绝缘子在线检测上的可行性。     

The mechanisms of pedestrian slip on flooring contaminated with solid particles

Statistics by the UK Health and Safety Executive (HSE) suggest that slips, trips and falls account for up to one in three major workplace accidents. The vast majority of these accidents are the result of contaminant (fluid or solid) within the shoe-floor contact. Though the lubrication mechanisms for liquid contaminants within the contact are well understood, the same cannot be said for particulate contaminants. This paper considers the key parameters controlling friction in a shoe-floor contact contaminated with various particles of different diameters and shape factors and floors with different roughness values (R_z). Experiments were conducted using a Stanley Pendulum Tester, which is the floor friction tester recommended by the HSE. Results suggest that the adhesive friction is significantly affected by particulate contaminants, while the hysteretic component is not. Three lubrication mechanisms identified as sliding, shearing and rolling have been observed depending on floor roughness, particle size and shape factor and have been plotted in a simple map to predict behaviour.     

A Model for the Assessment of Wheel–Rail Contact in the Presence of Solid Contaminants

An analytical model for the assessment of a contact in the presence of a solid contaminant is presented, mainly aimed at studying the damage to railway wheels and rails operating in third-body-contaminated environments. The model, developed under 2D plane strain idealization, includes multiple evenly spaced rigid cylindrical contaminant bodies entrapped between two elastic cylinders. It allows a very fast calculation of the pressure distribution on the surfaces in contact and it can be used for evaluating the stress field in the subsurface region, at both the small scale of the contact between the main body and the contaminant body and the full scale of the contact between the two main bodies. The model was validated by comparison with finite element (FE) analyses, showing its accuracy. Some examples of application showed the model’s ability to predict the limit of the influence of the solid contaminant bodies and the depth where cyclic plasticity phenomena occur in wheel–rail contacts.     

固相萃取工作站-气相色谱法测定污水处理厂进出水中有机污染物

本文采用全自动固相萃取仪富集城市污水处理厂总进水和二级出水样品中的酚、有机磷、多环芳烃和酯类等20种有机污染物质,萃取柱为反相柱ENVI-18,经浓缩仪浓缩后,使用气相色谱仪进行测定。同时进行了空白加标回收率测定,效果较好。使用本方法进行了两个城市污水处理厂的总进水和二级出水中有机物的测定。结果表明,污水处理厂的二级处理对上述有机污染物中50%以上的去除率可达到80%以上。     

城市污水冷热源污水污杂物分级浓度测试实验

对污杂物的性质、形状以及分级浓度进行了定义,并通过实验在典型时段对哈尔滨市两处具有代表性的污水干渠进行了现场测定.实验结果表明,污水中大尺寸污杂物浓度平均高达1.0kg/m3.实验数据将为理论研究和工程设计提供参考.     

固体颗粒污染物对节流调速回路速度启动特性的影响

通过试验分析固体颗粒污染物对液压节流调速回路启动时间的影响,在不同的污染条件下比较节流调速回路的启动时间,实验的结果有利于液压节流调速系统的设计和实施污染控制措施.     

砷化镓抛光晶片表面沾污的二次离子质谱分析

在砷化镓工艺过程中,很多失效问题与表面的沾污有关,二次离子质谱分析是表面分析的有力手段,本文提供一种用二次离子质谱分析检测砷化镓表面钠、钾和铝的沾污水平的测试方法。     

液态污染物对液压系统污染机理研究

液压系统污染物固态、液态、气态三种物理形态中,液态污染物由于种类繁多,对温度和气压反应敏感,作用机理比较复杂,对液压系统影响较大。文中对液态污染物种类、作用过程、主要危害进行研究,以对控制液压系统污染起到积极作用。     

低温等离子体降低柴油机NOx的研究

根据低温等离子体的净化机理,设计了一种新型低温等离子体净化装置,对柴油机不同负荷下,尾气中的氮氧化物进行处理试验。试验发现,净化装置净化效果明显,净化效率最高可达50%左右。该装置体积小、重量轻、功耗低,加以改进,对于汽车尾气排放控制具有很好发展前景。     

MQ—2000型高架门机管路系统清洗机

文章针对MQ－2000型高架门机液压同步顶升系统在制造安装过程中管路系统所受到的污染,分析了普通的滤油车不能对管路系统进行彻底清洗的原因,并由此给出了自行设计的管路系统清洗机的系统原理图。实践结果表明,所设计的管路系统清洗机满足了管路系统的清洗要求。     

The behavior of the liquid-like Langmuir's adsorbed film on air bearing surfaces

The contamination of slider air bearing surfaces may lead to a critical failure of hard disk drive systems. The contamination may be classified into two types: the liquid-like contamination and the particle contamination. In this study, the liquid-like contamination is concerned. It is assumed that the liquid-like contamination is caused by the adsorption of contaminant molecules in air. A mathematic model has been developed to predict the accumulating process of the liquid-like contaminant on air bearing surfaces. Numerical analysis of the behavior of the liquid-like adsorbed film for two different types of air bearing surfaces was conducted by using the proposed model based on the Langmuir adsorption. The results show that the contaminant tends to accumulate on the recession area of the air bearing surface when the viscosity of the liquid-like adsorbed film is low. However it may also accumulate in the front area of the air bearing surface when the viscosity is as high as 20 Pa s.     

Simple formula for the non-uniform contaminant deposition on a cylindrical human body surrounded by porous clothing

Characteristics of contaminant deposition on a human body underneath porous clothing were studied using numerical analyses of air flow and convective diffusion. A recirculation zone was formed in the middle of the air channel when the penetration Reynolds number exceeded a critical value; in this condition the deposition distribution showed a second peak. In the absence of recirculation, deposition decreased monotonically from the front stagnation point to ~0 at the rear stagnation point. A universal function was derived to quantify the spatial distribution of contaminant deposition and of the concentration boundary layer thickness.     

Practical contaminant analysis of lubricating oil in a steam turbine-generator

In order to identify the level of contamination of lubricating oil in a turbine-generator at a local power plant, contaminant analysis was conducted. The contaminant analysis was also used to assess the condition of tribo-components such as bearings, gears and bearing deflectors. Oil samples were taken and the debris in the used lubricating oil were analysed off-line to provide information for the construction of an on-line monitoring system. Statistical analysis of debris was also carried out to determine the quantitative trend of oil contamination. The on-line contaminant monitoring system was then developed with the capabilities to provide an early warning of excessive oil contamination and to detect any impending failures of tribo-components. Guidelines necessary for maintenance engineers such as preset warning level and a trip level (automatic shutdown) of contamination were established. In the system, a device utilizing a filter blockage principle was employed to measure the contamination level. The on-line system developed was installed and field tested in a turbine-generator at a local power plant. During the two year period of investigation, the lubricating system and related tribo-components were revealed to be in normal condition.     

Condition monitoring of electric motor ball bearings for the detection of grease contaminants

Grease used in the ball bearings of electric motors often get contaminated either from external particles or particles generated within these bearings. The effectiveness of vibration, stator current, acoustic emission and shock pulse measurements in detecting the presence of contaminant particles in bearing grease has been investigated. Silica and ferric oxide particles were used to contaminate grease. The levels of vibration, stator current, acoustic emission and shock pulse appreciably increased as contaminant level and contaminant size increased. Acoustic emission peak amplitude proved to be the best condition monitoring technique for the detection of grease contaminants in motor bearings. It is followed by shock pulse maximum value and carpet value in terms of effectiveness.     

Particle Entrapment in Hybrid Lubricated Point Contacts

This study proposes an innovative approach for the study of particle entrapment in rolling element bearings (REBs). Two couples of contacting materials were considered, the classical steel–steel and silicon nitride–steel used in hybrid bearings. Numerical simulations, as well as experiments, combine theoretical trajectories for incoming contaminant particles and effective entrapment ratios observed within a twin-disc machine. Linking both approaches allows the highlighting of some key parameters leading to particle entrapment under pure rolling conditions in elastohydrodynamic point contacts.     

Effect of volatile organic contamination on head-disk interface tribology and a method for its reduction

Volatile organic contamination is known to be one of the factors to cause the failure of head-disk interface (HDI). Therefore, reduction of its harmful effects and improvement of the stability and reliability of HDI is becoming an important issue. In this study, the effects of some model compounds of volatile organic contamination on the tribological characteristics of HDI were systematically investigated using a contact start/stop (CSS) tester. The slider surface after the CSS tests was analyzed using Time-of-Flight Secondary Ion Mass Spectroscopy (TOF-SIMS). Transfer of lubricating oil onto the slider surface was detected after the CSS tests. The organic contaminants promoted the transfer and resulted in high and unstable friction force. Fluorinated self-assembled monolayers (SAMs) were applied on the slider surface for reducing the transferred amount of the lubricating oil. Tribological performance of the slider coated with the SAMs and the transfer amount of lubricating oil onto the slider surface in the presence of contaminant was investigated. The friction force was low and stable in the case of the SAMs coated slider even under environmental contaminant. This result could be explained by the reduction of the transferred lubricating oil because the SAMs that coated on the slider surface were low surface energy.     

The Influence of Speed,Grease Type,and Temperature on Radial Contaminant Particle Migration in a Double Restriction Seal

Microparticle image velocimetry (μPIV) is used to measure the grease velocity profile in small seal-like geometries and the radial migration of contaminant particles is predicted. In the first part, the influence of shaft speed, grease type, and temperatures on the flow of lubricating greases in a narrow double restriction sealing pocket is evaluated. Such geometries can be found in, for example, labyrinth-type seals. In a wide pocket the velocity profile is one-dimensional and the Herschel-Bulkley model is used. In a narrow pocket, it is shown by the experimental results that the side walls have a significant influence on the grease flow, implying that the grease velocity profile is two-dimensional. In this area, a single empirical grease parameter for the rheology is sufficient to describe the velocity profile.

In the second part, the radial migration of contaminant particles through the grease is evaluated. Centrifugal forces acting on a solid spherical particle are calculated from the grease velocity profile. Consequently, particles migrate to a larger radius and finally settle when the grease viscosity becomes large due to the low shear rate. This behavior is important for the sealing function of the grease in the pocket and relubrication.