如何做好寒冷地区冬季施工的监理工作

探讨寒冷地区冬季施工的现场监理问题,提出了如何做好现场工程质量的监理,增强寒冷地区监理人员的责任心与使命感。     

影响屋面防水工程质量的剖析和防治措施

对目前建筑工程中造成屋面渗漏的进行剖析并提出相应的防治措施。     

A study on the prevention of cracks on the trepan area of motor bearing

Trepan prevents the wear of the inside part of a bearing when the initial shaft rotates. It continuously contacts with the eccentric part of the shaft in rotation and is loaded repeatedly. Therefore, even if an early crack of a trepan part is small, the crack may progress by the repeated load. If the crack progresses, very small chips come out. This is put in the rotor and prevents the rotation of the compressor. There can be leaks in a microgroove and extreme wear can occur due to lack of oil on the surface contact part. Therefore, this study was carried out to compare and investigate the trepan strength and deflection characteristics between trepan locations and dimension changes using the finite element method and search a motor bearing for a model with bigger stiffness of a trepan part and the same deflection.     

现浇钢筋混凝土框架质量通病的防治

对现浇钢筋砼框结构在施工中存在的质量问题提出了预防及治理措施。     

某深沟球轴承外圈开裂原因分析

在轴承套圈热处理时,炉内碳势的高低,会造成套圈表面脱、增碳现象。通过对627ZZ失效轴承进行检验分析后发现,热处理时碳势过高,引起表面增碳,导致开裂。     

Dependence of the frictional coefficient on the antifrictional-component concentration in the working layer of a slip bearing

We know that variation in the antifrictional-component concentration affects the frictional coefficient. The relation between factors affecting the frictional properties in the production of antifrictional materials is considered in a complete factorial experiment.     

Stability analysis of double porous and surface porous layer journal bearing

The linear stability analysis of double porous and surface porous layer journal bearing based on long and short bearing approximations is presented. The Brinkman model is employed in the porous region and the infinite permeability porous layer is simulated as surface layer. The coefficients of load, threshold speed and critical whirl frequency ratio are computed for double porous and surface porous layer configurations. The coefficients obtained using long and short bearing approximations yield same results. Higher threshold speed is obtained for double layer configurations of (i) high permeability bearing adsorbent porous layer topped with low permeability porous layer, and (ii) surface porous layer lubricant film.     

Prevention of fluttering fatigue damage in a tilting pad journal bearing

Tilting pad journal bearings have been widely used to support high-pressure/fast rotating turbine rotors owing to their inherent dynamic stability characteristics. However, fatigue damage in the upper unloaded pads and the break of locking pins by pad fluttering continuously take place in actual steam turbines. The purpose of this paper is to develop a bearing model that can prevent bearing problems effectively using pad fluttering in a tilting pad journal bearing. A developed bearing model with a wedged groove is suggested from studies of a fluttering mechanism performed in previous research. The fluttering characteristics of the upper unloaded pad are studied experimentally in order to verify the reliability of the bearing model. It was found that very little pad fluttering nearly occurs in the bearing model under various experimental conditions. In addition, no type of bearing failures by pad fluttering was detected in applications involving actual steam turbines.     

Study of the flaking-off phenomenon on a jet Engine's shaft bearing using the thin layer activation technique

The Thin Layer Activation technique has been applied in order to study the flake-off phenomenon on a jet engine's shaft bearing. The external track of the bearing has been activated following the reaction ⁵⁶Fe(p,n)⁵⁶Co, over a depth of 80 μm. In spite of a very low activation level, the first signs of flaking-off were detected 30 min before any significant increase in the vibration level appeared. At that point, the mass of particles leaving the track was measured on line, with a precision of 0.2 mg.     

Development of the zone method for inhomogeneous non-isothermal participating plane layer media

The purpose of this paper is to present the first step in developing the zone method for inhomogeneous media that has never been published in the literature. It was derived and formulated using matrix relations for a plane layer system enclosing a non-isothermal and inhomogeneous gray and absorbing, emitting and isotropically scattering media. The media are enclosed by two infinite parallel plates that are opaque, diffuse, and gray, but the formulations allow transparent plate. The formulations recover homogeneous cases and satisfy the conservation relations. The accuracy of the zone method is verified by comparing with available exact solutions. Through the accuracy check, validity of the zone method is also shown. Thus, formulations presented can be used to test the accuracy of the works by others for the problem in the study that has many applications in engineering and science.