Mixing Y(RE)BCO (RE=Nd,Sm) superconductors by crystal pulling method

Y_1−xRE_xBa₂Cu₃O_7−δ [Y(RE)BCO or REsBCO] superconductors were prepared by the crystal pulling method. The RE mixing content x in the crystal can be effectively controlled by the processing temperature. With an increase in processing temperature, the RE concentration in the liquid increased, which resulted in the higher RE substitution content in single crystals. The higher critical temperatures T_c above 92 K could be obtained by an optimized oxygenation treatment. The T_c value of Y(RE)BCO tends to be insensitive to the growth atmosphere of the oxygen partial pressure under a certain limit of the RE content. The Y_.727Nd_.273Ba₂Cu₃O_7−δ and the Y_.941Sm_.059Ba₂Cu₃O_7−δ samples show values of the critical current density J_c are about 2×10⁴ Acm⁻² at 1.2 T and 2.8×10⁴ Acm⁻² at 1.1 T for H//c, respectively, indicating that mixing REs 123 have obvious effects on J_c–H curves since RE ions are likely to substitute at both Y²⁺ and Ba²⁺ sites.     

Effect of the presence of fluid on the dynamic response of buried orthotropic cylindrical shells under a moving load

This paper deals with the theoretical analysis of the axisymmetric steady state dynamic response of a buried fluid-filled orthotropic cylindrical shell subjected to a radial line load moving along the axis of the shell. A thin shell is assumed to be perfectly bonded to the surrounding medium of infinite extent, and only the axisymmetric response has been included. A linear acoustic equation has been used for the wave propagation in fluid. The nature of variation of differences between the results of the empty and fluid-filled shells has been studied for varying soil conditions. Changes in results due to variation in the orthotropy parameters have been compared with the difference in results due to the presence of fluid inside the shell.     

NBI: A fortran program for molecular mechanics calculations on a microcomputer

A FORTRAN program for simple molecular mechanics calculations under the rigid-rotor approximation is presented. The program uses a potential energy function built up from cosine-type functions, for torsional terms, and modified Buckingham functions plus a Coulombic term, for non-bonded interaction. Although no automatic parameter optimization is implemented, “manual” parameter improvements can be performed very easily.     

Solvent-refined coal from high-ash non-coking coals and washery middlings for use in metallurgical coke making Part 1. Production,testing and characterisation

This paper presents studies on the preparation of a potential coking additive, solvent-refined coal (SRC), from typical high-ash Indian non-coking bituminous coals, tertiary Assam coal with a high sulphur content and washery middlings in a bench-scale unit (10 kg h⁻¹ coal throughput capacity) under hydrogen pressure. The extraction of the coal samples was conducted under moderate reaction conditions of temperature, pressure and residence time. No external catalyst was used in the process. Pre-beneficiated coal was used as the feed material and anthracene oil with a boiling range of 270–360°C was used as the solvent. Rigorous solid separation from the extract slurry by filtration was avoided by centrifugation in a super-decanter centrifuge to produce SRC with an ash content of 6–7%. The yield of SRC from non-coking Samla seam coal of the Raniganj coalfield was found to be 85% while its caking index was 44. Substantial improvement in the quality of blast furnace-grade coke was achieved by co-carbonisation of coking blends by mixing only 10% of the SRC prepared from Assam coal. The hydrogen requirement was low (1.5% wt/wt of d.a.f. coal) and recovery was of the order of 96% of the solvent used for the preparation of the coal-oil slurry. The yield of SRC and its quality as a coking agent are reported, along with the quality of the coke produced using SRC obtained from typical coal.     

滚切式联合剪切机组的发展

中厚板剪切线主要采用各种滚切剪将热轧精整后的钢板进行切边、切头和定尺,而将不同种类的滚切剪组合在一起形成联合剪切机组,是一项重要的技术工艺创新,可以获得良好的经济效益。概述了滚切式联合剪切机组的结构组成,并简要分析了组合剪的特点。     

科技进步与创新是我国人造板工业可持续发展的重要保障

从原材料来源与利用、功能性产品的开发、环保产品的开发以及节能减排技术的创新等几方面阐述了科技创新对我国人造板工业可持续发展的重要性.     

电力变压器高压套管末屏接地方式问题探讨

对电力变压器高压套管末屏的接地方式进行了分析,并提出了运行、检修中应注意的问题.     

800 kV罐式SF_6断路器的研制开发

介绍了新沈高800 kV罐式SF6断路器的研制开发过程和技术特点;基于气体质量守恒、能量守恒定律和牛顿第二定律,对其空载、T100s开断条件下压气室内气体压力特性进行了计算分析;应用有限体积法对其空载、T100s开断条件下二维气流场分布进行了计算分析;应用有限元计算方法,对其分合闸状态下的绝缘性能进行了计算分析;该罐式断路器的研制为中国750 kV输电线路的建设提供了经济可靠的技术和设备保障。     

变压器结构的三维模块化设计

介绍了在Pro/E绘图平台下,利用Intralink实现变压器结构的三维模块化设计.