Promoting contact strength of steel by rolling

The article deals with findings of experimental research on the running-in process of steel pieces with rollers that harden the contact strength. The hardening effectiveness of steel pieces physically simulates the bearing strain process, the physical and mechanical properties of the surface layer and its microstructure, and the diffusion of chemical elements by surface deformation using the chemical microanalyzer. The method and technology of running-in steel pieces of complex profile with the wedge roller and the device for the process implementation are developed. The findings are demonstrated for the adaptation of novel technology to production.     

智能复合控制系统的研究现状与展望

主要总结了近年来智能复合控制系统的研究与发展,介绍了智能复合控制的主要方面的研究成果,探讨了这一领域的研究趋向。     

Seasonal ultrastructural changes in apocrine gland cells in back skin of male brown bears (Ursus arctos)

Oily secretions from the back skin are involved in the marking behavior of male brown bears (Ursus arctos), and apocrine glands in back skin are activated during the breeding season. Here, we investigated seasonal changes in the intracellular organelles of apocrine gland cells in the back skin of male brown bears using transmission electron microscopy (TEM) and osmium‐maceration scanning electron microscopy (OM‐SEM). The morphological features of mitochondria and intracellular granules, and secretory mechanisms obviously differed between breeding and non‐breeding seasons. The TEM findings showed that contents of low‐density granules were released into the glandular lumen by frequent exocytosis, and sausage‐shaped mitochondria were located in the perinuclear region during the non‐breeding season. In contrast, high‐density granules appeared in the apical region and in projections during the breeding season, and swollen mitochondria and lysosome‐like organelles separating into high‐density granules were located in the perinuclear region. The OM‐SEM findings revealed swollen mitochondria with only a few partially developed cristae, and small mitochondria with cristae shaped like those in swollen mitochondria in the apical regions during the breeding season. These findings indicated that the small mitochondria corresponded to the high‐density granules identified by TEM. These findings suggested that mitochondria in apocrine gland cells swell, degenerate, fracture into small pieces, and are finally released by apocrine secretions during the breeding season. Small mitochondria released in this secretory manner might function as the source of chemical signals in the oily secretions of brown bears during the breeding season.     

拼焊板冲压成形与成形极限研究

概括了拼焊板在车身覆盖件冲压成形中的应用和技术优势,综述了拼焊板的冲压成形性能和成形问题及其影响因素,简要介绍了国内外在拼焊板冲压成形极限方面的研究现状和研究成果,重点讨论了在拼焊板冲压成形极限研究中仍存在的问题和进一步的研究发展方向。拼焊板的冲压成形及其成形极限的研究对汽车覆盖件冲压成形和未来汽车设计具有重要的理论和现实意义。     

Real-time in vivo imaging collagen in lymphedematous skin using multiphoton microscopy

Changes of dermal collagen are characteristic for chronic lymphedema. To evaluate these changes, a real-time imaging based on two-photon excited fluorescence and second-harmonic generation was developed for investigating collagen of lymphedematous mouse and rat tail skin in vivo. Our findings showed that the technique could image the morphological changes and distribution of collagen in lymphedematous mouse and rat tail skin in vivo. More importantly, it may allow visualization of dynamic collagen alteration during the progression of lymphedema. Our findings demonstrated that multiphoton microscopy may have potential in a clinical setting as an in vivo diagnostic and monitoring system for therapy in lymphology.     

Experimental analysis of factors influencing the cage slip in cylindrical roller bearing

This paper deals with the effect of operating parameters on cage slip in cylindrical roller bearing. A cylindrical roller bearing test rig is developed to measure the running speed of bearing elements at various operating conditions. The effect of operating parameters namely shaft speed, radial load, viscosity of lubricating oil, number of rollers, and bearing temperature on cage slip are experimentally obtained. The critical load and magnitude of cage slip for various operating conditions are obtained. The non-dimensional number is derived based on the operating parameters. The region where cage slip occurs is developed from the derived non-dimensional number and the experimental data. The temperature raise is experimentally obtained during slip condition and its effect on viscosity is included for calculations. The frictional forces are experimentally obtained and are compared with the theoretical findings. The significant effect of operating parameters on cage slip of cylindrical roller bearing is discussed based on the experimental findings.     

Approximate expressions for electron lens properties*

New approximate formulae for the focal length and principal aberration coefficients of electrostatic and magnetic lenses have been suggested by Crewe. These are compared with earlier approximate expressions and similarities and differences are indicated; they are also compared with calculated values for some real lenses. These comparisons confirm Crewe's findings and elucidate some unexplained features of these.     

机械零件毛刺控制及去除工艺现状

阐述近几年来机械制造领域中毛刺控制技术的研究成果及研究进展，列出了毛刺去除工艺的应用状况、新的去毛刺方法及其研究，并指出了去毛刺技术的发展方向。     

高校管理干部的领导行为、领导风格和领导技能分析——以北京市属高校的管理干部为调查对象

本研究抽样调查了高校管理干部的领导行为、领导风格和领导技能的整体状况;比较了不同性别、不同专业背景和不同毕业院校的高校管理干部领导力方面的差异.从整体状况来分析,高校管理干部在领导行为方面更倾向于关系维持,在领导风格方面更倾向于民主型,在领导技能方面人际关系技能和概念技能较高,管理技能稍弱.从差异性来看,男性高校管理干部的领导技能比女性稍高,偏爱权威型的领导风格且对任务维度更为关注.文科和理工科背景的管理干部的领导力状况差别不明显,但后者更关注任务维度.然而,毕业于重点与非重点院校的高校管理干部的领导力状况没有明显差异.因此,高校在遴选管理干部时要消除专业背景和毕业院校与领导力相关的一般观念,同时要采取多种方式来提高女性干部的管理技能,并给管理干部更大的实践空间.     

Photogrammetric measurement process capability for metrology assisted robotic machining

This paper documents the findings of experiments done to assess the capability of a photogrammetric measurement process for use in a metrology assisted robotic machining application. Capability is judged from the perspective of uncertainty and error across various part geometries over several days. The influence of operator technique on error and point acquisition ability for challenging geometry is also assessed. The process is found to be resistant to short-term error drift when operating in a controlled environment but systematic and random errors are demonstrated to be highly dependent on geometry. Operator influence on capability is found to be minimal when scanning freeform geometry, although this is unlikely for more complex parts. Acquisition of inspection points on cylindrical pockets is found to be a limitation. Technological development opportunities are highlighted in the context of the metrology assistance application considered. Overall, a thorough assessment of the measurement process capability is made and findings provide a quantification of current state, setting a base case for comparing research progress against.     

Externally Pressurized Spherical Gas Bearings

Spherical gas-lubricated bearings are of considerable interest in applications requiring a pivoting or rotating support with three degrees of freedom, for instance hi attitude control simulators of space vehicles. An analytical and experimental study of externally pressurized spherical gas bearings with orifice regulation is presented along with the experimental findings, which are in good agreement with the predictions of the viscous flow theory.     

ZL40B装载机弧齿锥齿轮质量分析报告及对策

通过对 ZL4 0 B装载机主传动弧齿轮锥齿轮进行性能分析 ,对存在的问题进行分析并提出解决的办法 ,其结论对装载机传动系统的设计具有指导意义。     

机械行业信息化水平测度的研究

本文运用主成分分析方法对机械工业所属的6个分行业——金属制品业、普通机械制造业、专用设备制造业、交通运输设备制造业、电气机械及器材制造业和仪器仪表及文化办公用品制造业进行了产业信息化水平的实证分析,也基本上反映了我国机械工业信息化水平的现有状况。本文的研究结果对分析我国产业信息化水平的相关研究有一定的参考作用,测度方法对其他产业信息化水平的研究分析工作也有较大的参考借鉴价值。     

Resolution effect on the stereological estimation of surface and volume and its interpretation in terms of fractal dimensions

Estimating surface and volume density of subcellular membrane systems at different magnifications yield different results. As the magnification is increased from × 18,000 to × 130,000 the estimates of surface density of endoplasmic reticulum and inner mitochondrial membranes increase by a factor of 3, whereas that for outer mitochondrial membranes increases only by 20%. The estimate of volume density of endoplasmic reticulum also increases by a factor of 3. No further increase is observed at magnifications above × 130,000 which is therefore called critical magnification. The findings are interpreted on the basis of the concept of fractals proposed by Mandelbrot, and the fractal dimensions of the membrane systems considered are estimated. This can lead to the derivation of resolution correction factors which permit measurements obtained at any magnification to be converted to estimates at critical magnification. These findings may explain, at least in part, the large discrepancy in the estimates of the surface of cytomembranes found in the literature.     

Determining the optimal scale width for a rating scale using an integrated discrimination function

How to determine the optimal number of response categories for a rating scale has been debated for more than 100 years and has not yet been solved thoroughly. This study aims to provide an approach to determine the issue for stimulus-centered rating scale. We are one of the first to develop an integrated discrimination function of scale width and the number of stimuli, by integrating the findings about information transmission, reliability, effects of stimulus number and Shannon’s information entropy theory. The optimal scale width is determined by optimizing the integrated discrimination function for any given number of stimuli. We validate the proposed model to predict the findings of the empirical research in information transmission, response reliability, and accuracy. We also propose the concept of scoring validity and suggest a heuristic criterion to judge the validity.     

The effect of fibrous fillers and metallic powders on the triboengineering characteristics of frictional composites based on the combined phenol-rubber binder

The findings of studies of the triboengineering characteristics of frictional composites based on the combined phenol-rubber binder filled with glass, basalt, carbon, and polyoxadiasol fibers and copper and iron powders are presented. The fibrous filler type and quality are found to influence the strength, friction, and wear characteristics of the composites. It is demonstrated that the composites filled with metallic powders have better thermal and physical characteristics.     

Analytical modelling of kirschner wires in Ilizarov circular external fixators using a tensile model

Mechanical characteristics of orthopaedic fixators, such as the stiffness and stability, directly influence the mechanobiological environment in which the bone is healed. In circular external fixators, the transfixing Kirschner wires are the major contributors to the biomechanics involved. A comprehensive understanding of the mechanical behaviour of the wires is therefore the key to biomechanical analysis of the Ilizarov fixator. In this study, to model the behaviour of the wires, a purely theoretical approach has been adopted to obtain explicit equations for a solely tension-based model formulation. Mathematical modelling leads to new algebraic polynomials whose solutions are the exact maximum deflection, angle of deflection, and total (final) tension in the wire. The predictions are compared with published experimental and computational findings on the deflection and stiffness of the wires, and analytical explanations are provided for the previously observed behaviours. Parametric (practical) implications of this type of abstraction include the fact that the angle of deflection as well as the tension in the wire are independent of its length. The inverse proportionality of wire stiffness to its length is also deduced. The findings are applicable to tensile elements (ropes, chains, etc.), provided that the tensile deformation (elongation) can be deemed to be the dominant mode of deformation.     

月球车润滑与密封技术综述

本重点介绍月球车系统摩擦失效以及由此产生的润滑与密封问题。美国航空航天局(NASA)研究表明摩擦失效是限制月球车使用寿命的主要因素，月球车关键组件的发展离不开润滑与密封技术的支持。为保证月球车在其使用年限内正常工作，润滑与密封技术就成为发展月球车关键技术之一。     

Analysis and synthesis of eccentric chainwheel drives

An analysis is presented which proves the kinematic feasibility of a chain drive in which the driving and jockey wheels are eccentric and the driven wheel is concentric, the axes of rotation of all three wheels being fixed. Application of the analysis is found to confirm the findings of previous work.     

New observations on the mechanism of chip formation when machining titanium alloys

Titanium and other aerospace structural superalloys are extremely difficult to machine except at low cutting speeds because of rapid tool wear. To increase productivity it is necessary to understand the mechanics of chip formation when machining these alloys. In this paper we report some new findings towards that goal.