Specific features of the influence of hydrogen on the properties and mechanism of fracture of the metal of welded joints of steam pipelines at thermal power plants

We study the standard tensile mechanical properties of a live-steam pipeline operated for about 2 · 10⁵ h and model (repair) welded joints. As a result of the degradation of weld metal under service conditions, its strength becomes lower than that of base metal. We show that the unregulated orientation of specimens along the axis of a welded joint is the most acceptable for detecting the degradation of weld metal. Cathode polarization facilitates evaluating the state of the degraded weld metal and that of the base metal. We have also disclosed the specific features of the influence of internal (preliminary hydrogenation) and external (electrolytic hydrogenation in the course of tests) hydrogen on the properties and mechanisms of the fracture of weld metal. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 42, No. 4, pp. 26–35, July–August, 2006.     

Doppler ultrasonography in successful varicocele surgery

The authors examined 47 patients after operation on account of varicocele by colour flow mapping and Doppler frequency analysis. In addition they evaluated the postoperative finding clinically and examined also the spermiogram. The greatest success of surgical treatment was observed after laparoscopic ligature of the v. spermatica--a success rate of 91% was recorded after this operation. Bernardi's operation was successful in 62%, Paloma's in 56% of the patients. From 18 patients with a pathological spermiogram before operation they observed improvement in 25%.     

Edge dislocation climb over non-deformable circular inclusions

Edge dislocation climb over non-deformable circular inclusions is studied as a possible rate limiting mechanism for creep of dispersion strengthened metals. The inclusion and matrix are assumed to exhibit no misfit and to be elastically isotropic, with the inclusion, more rigid than the matrix. The climb motion of the dislocation is assumed to be diffusion controlled and very much slower than glide. We calculate the path taken by the dislocation as it climbs past the inclusion. Special attention is given to the equilibrium separation distance between the dislocation and inclusion, the total climb distance required to pass the inclusion and the total lag time imposed on the dislocation motion by the presence of the inclusion. We discuss the results of these calculations and their implications in connection with the problem of creep of dispersion strengthened metals.     

Influence of Hydrogen on the Formation of Fatigue Thresholds in Structural Steels

We analyze certain phenomena related to the influence of gaseous hydrogen and hydrogen dissolved in a metal on the near-threshold growth of fatigue cracks. The significant decrease in crack growth resistance due to the action of hydrogen as compared with that in vacuum is caused mainly by the adsorption decrease in strength due to adsorption. We established three factors of the ambiguous influence of hydrogen on the effective fatigue threshold K _theff, for which a positive influence is replaced by a negative one, namely: the strength level, temperature of testing, and high-temperature degradation of the metal. The following fractographic peculiarities of the near-threshold growth of cracks in a degraded metal are revealed: the local tunneling along the front of a crack and the presence of fatigue grooves. We propose a mechanism of crack closure due to both roughness and the component of longitudinal shear at the tip of the crack. We analyze the scale effect of fatigue thresholds, determine the conditions for invariance of the parameter K _theff under conditions of plane deformation, and established the dependence of K _theff on the thickness of specimens in the case of tests of a hydrogenated degraded metal.     

我是麦霸

夏亚：哟哟哟～又一个梦幻系列，哈哈～看来我们的电饭煲又有新花样可以品尝啦!下面就来看看最新的《妖怪A梦》吧!     

Equipment selection and justification through total productivity model

Traditional methods of economic analysis to justify equipment selection and use are based on several methods such as the Net Present Value, Break-Even Analysis, Pay-Back Period, Return on Investment, among others. However, with the introduction of automation, Flexible Manufacturing Systems (FMS), and Computer Integrated Manufacturing Systems (CIMS), such economic analyses have often resulted in decisions that management did not like to support but did not have much choice to avoid on account of pressure from manufacturing engineers, design engineers and others in the operations areas. The real problem of equipment selection and justification lies in the methodologies used.

This paper presents a unique approach to equipment justification by applying Sumanth's TOTAL PRODUCTIVITY MODEL, whereby the anticipated impact of the proposed equipment on profitability is assessed from the point of total productivity and the five partial productivities. Then, only if the equipment increases the total productivity level beyond its break even point, the equipment is selected or justified.

This method offers a non-traditional approach to justifying and selecting equipment in all types of environment. A numerical example is presented by using LOTUS 1-2-3^TM on an IBM PC. Advantages and limitations to this approach are discussed to provide a balanced perspective on the important issue of equipment selection and justification.     

铜厚膜环行器的研制

采用新型的在大气气氛中烧结的铜厚膜多层导电浆料,应用厚膜混合技术制作了2。2GHz和2.8GHz的环行器。其性能指标可与同类型采用薄膜贵金属制作的环行器相媲美,且工艺简单,成本低及生产周期短。     

A micro computer decision support system for the total-productivity model (TPM)

The Total Productivity Model (TPM), developed by Sumanth in 1979, has been applied to a number of situations involving manufacturing as well as service-oriented operations. The diversity of applications on the one hand, and the flexibility of usage of the microcomputers on the other hand, have helped to focus the need for a micro-computer based Decision Support System (DSS). This paper presents such a system using the Macintosh Computer. This DSS is a highly interactive, menu-driven program that can provide on-the screen capabilities of individual operational units as well as the firm that comprises of them. The system has several convenient features to assess the “PRODUCTIVITY- ORIENTED PROFITABILITY” of any type companies/organizations. The system logic and flow chart, data input and output formats, and sensitivity analysis will be shown and discussed in the paper. A balanced critique will be offered to view the system in a proper perspective with respect to structural elements of the Decision Support System.     

利用GTD分析微波双反射面天线效率

本文根据场相关定理,应用几何绕射理论(GTD),分析计算主面为抛物面,副面为任意旋转对称面的微波双反射面天线效率.通过实际证实,运算简明,效果良好.     

大嘴救援站

Q 车载播放器不认优盘怎么办？ 为什么爸爸的汽车不认我的优盘呢？国庆的时候出去玩，我把歌曲都复制到优盘上了，但是插进去却一点反应都没有；我还以为优盘被汽车弄坏了，后来插到电脑上，歌都那儿摆着呢!（杨雅冰 广州 读者来信）