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61.
In the present work, high temperature tensile properties and abrasive wear performance of a microalloyed medium carbon steel has been examined. Tensile and abrasive wear testing were carried out on as-received and heat treated specimens. The research has shown that microalloyed medium carbon steel was susceptible to dynamic strain ageing due to interaction of mobile dislocations and solid atoms, such as carbon and/or nitrogen. The interaction between dislocations and solid atoms at 200–300 °C changes the work hardening rate and contributes to dynamic strain ageing. These interactions also increased abrasive wear resistance of the microalloyed medium carbon steel at 300 °C. Therefore, the inference can be drawn that dynamic strain ageing caused an improvement on abrasion resistance. 相似文献
62.
The calculations of the elastic scattering properties of ultra-cold francium isotopes are reported in detail. A parametric model potential for the triplet molecular states of the Fr2 is represented, and the scattering lengths at and the effective range re are calculated using WKB and Numerov methods for Fr--Fr in the triplet state. The convergence of these scattering properties depending on a K0 parameter and core radius is also investigated using two methods: Quantum Defect Theory and analytical formula of Symskoviski. 相似文献
63.
In this study we consider a rescheduling problem on identical parallel machines. The rescheduling is undertaken because of a period of unavailability on one of the machines. We consider the total flow time as an efficiency measure and stability is gauged in terms of the number of jobs processed on different machines in the original and new schedules. We show that all efficient schedules with respect to efficiency and stability measures can be generated in polynomial time. 相似文献
64.
一株丝状真菌发酵法产红色素培养基的研究 总被引:1,自引:0,他引:1
研究了一株丝状真菌Miug-2.7发酵法生产红色素的液体培养基最佳组分,以及液体发酵培养基最佳配方.结果表明,本试验范围内最佳质量配比是淀粉3%,蛋白胨1.0%,诱导物1%,起始pH7.5. 相似文献
65.
王为 《湖北工业大学学报》2003,18(4):23-26
介绍了先进制造技术的发展历程及其系统体系,重点阐述了现代制造系统工程设计技术的重要地位,并对我国加入世贸组织后制造业前景作了简要展望. 相似文献
66.
基于快速原型制造技术的产品开发 总被引:2,自引:0,他引:2
介绍了适应市场的快速响应设计技术的内容,关键技术和具体实施策略,快速响应设计在企业竞争中的作用.同时说明了快速原型制造技术在快速制造中的作用. 相似文献
67.
Microstereophotolithography using a liquid crystal display as dynamic mask-generator 总被引:2,自引:0,他引:2
A new laser microstereophotolithography process has been developed in our laboratory to manufacture three-dimensional parts
with a high accuracy. As usual in laser stereophotolithography or laser microstereophotolithography, the part is manufactured
layer by layer by a light-induced space-resolved polymerization. Until now, in all the already existing microstereophotolithography
devices a layer is manufactured vector by vector, by moving the part beneath the initiating light source which remains motionless.
We developed a simpler and easier process, in which we can manufacture an entire layer by irradiating its whole surface only
once: we used a liquid crystal display as a dynamic generator of masks. In the device we set up, we need only one mobile element,
the z translator, all the others are fixed. We manufactured several different 3D microparts, in particular a piece of bevel
microgearing with helicoidal cogs, the volume of which is less than half a cubic millimetre.
Received: 14 December 1995 / Accepted: 16 September 1996 相似文献
68.
Optimal design of frames including cross-sectional dimensions (size parameters) and rigid joint positions between beams (configuration parameters) is treated in the paper. The optimal design corresponds to a minimal mass structure with constraints set on damping capacity of free vibration modes. The sensitivity analysis of distinct as well as multiple frequencies is performed analytically using a complex variable sensitivity method. The linking process of size and configuration variables is applied to generate different classes of optimal designs. The numerical algorithm is based on quadratic approximation of the objective function and linear approximation of active constraints. The examples are provided for 2, 12, and 124 beam frames.Presented at WCSMO-2, Zakopane, Poland, May 26–30, 1997 相似文献
69.
M. Hjiaj Z‐Q Feng G. de Saxc Z. Mrz 《International journal for numerical methods in engineering》2004,60(12):2045-2076
This paper presents an algorithm for solving anisotropic frictional contact problems where the sliding rule is non‐associated.The algorithm is based on a variational formulation of the complex interface model that combine the classical unilateral contact law and an anisotropic friction model with a non‐associated slip rule. Both the friction condition and the sliding potential are elliptical and have the same principal axes but with different semi‐axes ratio. The frictional contact law and its inverse are derived from a single non‐differentiable scalar‐valued function, called a bi‐potential. The convexity properties of the bi‐potential permit to associate stationary principles with initial/boundary value problems. With the present formulation, the time‐integration of the frictional contact law takes the form of a projection onto a convex set and only one predictor–corrector step addresses all cases (sticking, sliding, no‐contact). A solution algorithm is presented and tested on a simple example that shows the strong influence of the slip rule on the frictional behaviour. Copyright 2004 John Wiley & Sons, Ltd. 相似文献
70.