Stability of a crystal surface in fractional crystallization on a band

The problem on the morphological and thermal stability of a crystal surface in fractional crystallization on a band has been investigated theoretically. A model to describe the dynamics of the development of a striped perturbation of the crystal surface is suggested. It is used as a basis for analyzing the influence of the main factors on the stability, and a stability criterion has been derived. It has been established theoretically that the thermal instability must appear at small Reynolds numbers (Re < 10). Numerical experiments have shown that an increase in the length of the band, its inclination angle, as well as a decrease in the rate of melt feed and in the band motion velocity increase the thermal instability. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 82, No. 1, pp. 106–113, January–February, 2009.     

MPLS VPN在山西电力调度数据网的应用

山西电力调度数据网是山西电网调度实时监控系统及与调度生产直接相关的各应用系统信息传输的基础平台,是山西电网调度生产的专用数据网络.本文讨论了山西电力调度数据网络的拓扑结构、组网方案、路由组织等.     

Inverse design of directional solidification processes in the presence of a strong external magnetic field

A computational method for the design of directional alloy solidification processes is addressed such that a desired growth velocity ν_f under stable growth conditions is achieved. An externally imposed magnetic field is introduced to facilitate the design process and to reduce macrosegregation by the damping of melt flow. The design problem is posed as a functional optimization problem. The unknowns of the design problem are the thermal boundary conditions. The cost functional is taken as the square of the L₂ norm of an expression representing the deviation of the freezing interface thermal conditions from the conditions corresponding to local thermodynamic equilibrium. The adjoint method for the inverse design of continuum processes is adopted in this work. A continuum adjoint system is derived to calculate the adjoint temperature, concentration, velocity and electric potential fields such that the gradient of the L₂ cost functional can be expressed analytically. The cost functional minimization process is realized by the conjugate gradient method via the FE solutions of the continuum direct, sensitivity and adjoint problems. The developed formulation is demonstrated with an example of designing the boundary thermal fluxes for the directional growth of a germanium melt with dopant impurities in the presence of an externally applied magnetic field. The design is shown to achieve a stable interface growth at a prescribed desired growth rate. Copyright © 2001 John Wiley & Sons, Ltd.     

山东昌乐新生代玄武质岩石中的刚玉及共存矿物

昌乐方山新生代玄武质岩石中的刚玉具有明显的不同世代的结晶特征。分析与刚玉共存的各种矿物稳定存在的温度、压力范围，可以推断不同世代的刚玉结晶时的温压条件。     

考虑粘结滑移的RC非锚固区段平均本构关系

根据静力平衡和变形协调,针对受拉裂缝处钢筋的不同应力阶段分别考虑粘结强度变化和裂缝宽度发展的影响,推导了钢筋混凝土结构非锚固区段在粘结滑移作用下的平均应力—应变关系。应用平均平均本构关系对典型的钢筋混凝土梁试验进行非线性模拟,并与试验结果进行对比,分析表明：采用平均本构关系考虑钢筋混凝土非锚固区段粘结滑移作用的分析模型,可以获得与试验相近的计算结果,并能简化非线性分析过程。     

Effect of intermetallics on susceptibility of Mg alloy welds to liquation cracking

ABSTRACT

The circular-patch welding test was used to study the liquation and liquation cracking of AZ-series Mg alloys. A heat treatment was carried out on the as-received AZ91 alloy to dissolve the γ(Mg₁₇Al₁₂) particles before welding. The circular-patch welding test was then conducted on the heat-treated, as-received AZ91 alloy using AZ61 and AZ91 filler wires. The results showed that the susceptibility of AZ91 alloy to liquation and liquation cracking was significantly reduced by the dissolution of massive γ(Mg₁₇Al₁₂) particles via a heat treatment before welding as the liquation mechanism was changed. Both constitutional liquation and incipient melting occurred in the partially melted zone of the as-received AZ91 welds, while only incipient melting occurred in the heat-treated AZ91 welds.     

非常规分割线的构成方法及其创意

非常规分割线能充分展示现代女装设计中变化多端的造型需求。结合实例,分别运用平面裁剪、立体裁剪、平面与立体相结合 的裁剪方法对非常规分割线进行研究,对各种不同方法得到的样版在省道量转移、松量、丝绺方向、样版准确度、成衣效果等各方面进行分析和比较,归纳总结非常规分割线不同构成方法的规律和差异。通过对非常规分割线结构设计原则的应用,在分割线处加入褶裥或空间量等方式实现服装结构创意,满足服装设计个性化需求。     

自蔓延离心熔铸TiB2-(Ti,W)C-TiC陶瓷研究

基于离心热爆反应、难熔液相分离与快速凝固原理,选取(WO3+Al+C)体系辅助(B4C+Ti)反应体系,采用自蔓延离心熔铸工艺可以成功制备出TiB2微纳米晶补强TiC-(Ti,W)C陶瓷基复合材料.将(B4C+Ti)、(WO3+Al+C)两种反应体系依次装填入坩埚中进行SHS离心熔铸实验,发现因W-Ti-C液相动力学粘度的降低、Al2O3液滴迁移路程减小,极大促进Al2O3液滴的Stokes上浮过程,故而显著减小残存于陶瓷基体上的氧化物夹杂含量与尺寸,进而TiB2微纳米片晶诱发的强烈自增韧机制与Al2O3微纳米晶产生的残余应力增韧效应,使得TiB2-(Ti,W)C-TiC陶瓷的弯曲强度、断裂韧性与维氏硬度分别达到(952±25)MPa、(12.6±2.5)MPa·m1/2与(28.6±1.2)GPa.     

Housing policy in the UK: the importance of spatial nuance

The UK has been engaged in an ongoing process of constitutional reform since the late 1990s, when devolved administrations were established in Northern Ireland, Scotland and Wales. As devolution has evolved there has been a greater trend towards divergence in housing policy, which calls into question any notion of a ‘UK experience’. Whilst the 2014 Scottish independence referendum again returned constitutional reform high onto the political agenda, there still remain tensions between devolved governments and the UK Government in Westminster, with England increasingly becoming the outlier in policy terms. Informed by ideas of social constructionism, which emphasises the politics of housing, this paper draws on an analysis of policy narratives to highlight the need for greater geographical sensitivity. This requires not only more spatial nuance, but also a recognition that these differences are underpinned by divergent political narratives in different parts of the UK. This emphasis on the politics underpinning policy has relevance internationally in other geographical contexts.