核电站稳压器封头带极埋弧堆焊工艺技术

采用带极埋弧堆焊对核电站稳压器半球形封头进行大面积超低碳奥氏体不锈钢耐蚀层堆焊,设计制造了专用装配胎具和辅助曲面垫板,配合100t焊接变位器,采用ESAB焊机完成封头内壁整个曲面的堆焊。讨论了电流、电压、焊接速度、焊道搭接量和工件放置水平度对堆焊质量的影响。确定了合适的焊接参数,最终完成了两台稳压器4个封头内壁堆焊。     

放顶煤开采顶煤运移实测与损伤特性分析

通过分析几个放顶煤工作面顶煤运移实测结果并结合顶煤破坏与非破坏的概念，认为顶煤运移特点和过程符合损伤力学基础，阐述了建立顶煤运移损伤特性方程的原理和方法，并有示例说明     

乡村地区可持续的旅游业--历史建筑保护、修复和功能转换

本文为2004年召开的第七次中德建筑研讨会的会议论文之一,结合实际事例论述了德国农村地区在可持续发展建设过程中传统建造技术、地域形式和传统材料的应用。     

Neue Methoden zur Beurteilung der Betriebsfestigkeit im Fahrzeugauslegungs‐ und ‐absicherungsprozess

Advanced durability evaluation in vehicle design and validation process The modern process of evaluation and validation conducted in the automotive industry uses experimental, metrological, and calculation‐based methods. Offering various examples, the present paper describes new developments in the determination and evaluation of operating strength, particularly in terms of virtual methods and their application in practice. The first point considered is the virtual determination of load data, the second is the improvement of calculated fatigue life. Two current examples in the development of methods are presented in this context: The first example examines the inhomogeneity of materials in calculating aluminium castings. The second example describes the approach taken in the configuration of components made of short‐fibre‐reinforced polymers, applying a new method of calculation.     

150 t超高功率电弧炉整体浇注小炉盖的研制与应用

以特级矾土、电熔棕刚玉、电熔白刚玉等为主要原料,加入一定量的α Al2O3微粉和氧化铬微粉,用纯铝酸钙水泥作结合剂,外加微量防爆纤维、不锈钢纤维和分散剂,制作整体浇注的电弧炉小炉盖。研究了α Al2O3微粉和氧化铬微粉对试样冷热态强度性能、致密性、施工性能的影响;对比了Polyg、Darvan和M（复合型）分散剂的效果,最终筛选出最佳组合方案：α Al2O3微粉合适加量为2a%,氧化铬微粉合适加量为2c%;分散剂选用M型粉末。采用该组合方案制作的预制件试样性能完全满足了实际需要。采用该方案制作的整体浇注小炉盖应用于国内某钢厂150 t超高功率交流电弧炉,其使用寿命由原平均180炉左右提高到537炉,最高达到676炉,效果非常理想。     

Performance analysis of a feasible air-cycle refrigeration system for road transport

The performance of an air-cycle refrigeration unit for road transport, which had been previously reported, was analysed in detail and compared with the original design model and an equivalent Thermo King SL200 vapour-cycle refrigeration unit. Poor heat exchanger performance was found to be the major contributor to low coefficient of performance values. Using state-of-the-art, but achievable performance levels for turbomachinery and heat exchangers, the performance of an optimised air-cycle refrigeration unit for the same application was predicted. The power requirement of the optimised air-cycle unit was 7% greater than the equivalent vapour-cycle unit at full-load operation. However, at part-load operation the air-cycle unit was estimated to absorb 35% less power than the vapour-cycle unit. The analysis demonstrated that the air-cycle system could potentially match the overall fuel consumption of the vapour-cycle transport refrigeration unit, while delivering the benefit of a completely refrigerant free system.     

[111] Heterostructures for Spin Devices

The symmetry properties of [111] quantum wells (QWs) and superlattices, and in particular the fact that the symmetry is not reduced when bulk inversion asymmetry (BIA) is supplemented with structural inversion asymmetry [SIA (Rashba)], have important consequences for spin dynamics and transport. We compute the effective spin Hamiltonians for [111] and [110] structures, and show that for the [111] case the splitting can be made to vanish to lowest order when BIA and SIA effects are of equal strength. As a consequence, the Dyakonov–Perel spin relaxation mechanism is suppressed for all spin components. This effect forms the base for an improved version of the Datta–Das and a recently proposed family of spin transistors. For [110]-grown QWs, the effect of SIA is to augment the spin relaxation rate of the component perpendicular to the well. We derive analytical expressions for the spin lifetime tensor and its proper axes, and see that they are dependent on the relative magnitude of the BIA- and SIA-induced splittings.     

Single-crystal neutron diffraction: a valuable tool for probing bond activation in transition metal σ complexes

Transition metal complexes are ubiquitous intermediates in metal-catalyzed reactions, including hydrogenations, activation and functionalization reactions of hydrocarbons, and hydroborations. For over 20years, single-crystal neutron diffraction has been exploited to investigate bond activation in these systems. Topics investigated include H–H activation in H2 complexes, C–H activation in agostic systems and, most recently, B–H activation in a catecholborane metal complex. These results are illustrated here drawing upon studies carried out at both pulsed neutron sources and steady-state reactors. Despite notable successes such as those that we highlight, however, single-crystal neutron diffraction has seen somewhat limited application here to date primarily due to the need for large crystals. Revolutionary improvements are anticipated with the advent of a new generation of sources including the Spallation Neutron Source (SNS) that is scheduled to become operational at Oak Ridge, TN in 2006. At the SNS, it will be possible to work with crystals approaching the size commonly used in X-ray studies employing laboratory sources and to greatly expand the range of materials that are open to investigation.*To whom correspondence should be addressed.     

Dynamics of Lifeboat and Boom in Deployment from a Moving Support

The equations governing the boom-assisted deployment of a lifeboat from a moving support are formulated in three dimensions using Kanes method, accounting for the coupling of the dynamics of the boom and lifeboat. The effect of wind loading is included. At splashdown we assume a controlled water entry and hence the buoyancy force, but not impact force, is modeled. The equations are solved numerically using a standard Runge-Kutta MATLAB routine. Comparison with a known solution for a special case is illustrated.