Effect of Strain Rate on Discontinuous Flow and Mechanical Characteristics of High-Nitrogenous Steel

Experimental study on the effect of strain rate on discontinuous flow and mechanical characteristics of the high-nitrogenous steel Kh23AG19F has been performed. Within the range of strain rates from 4.62 · 10^-5 to 1.85 · 10 ^-4 s^-1, discontinuous flow, reflected by serration on the tensile diagram, is chiefly determined by intergranular deformation mechanisms. Under strain rates over 1.85 · 10^-2 s^-1, combined deformation modes prevail, which cause a change in the character of discontinuous flow and transform a serrated tensile diagram into a wavy graph, with the yield stress of steel increased significantly.     

基于BOOSt结构下不连续导电模式的PFC电路

采用现代高频功率变换技术的有源功率因数校正（Power Factor Corrector,PFC)技术是解决高频开关变换器谐波污染的有效手段。与传统的PFC电路相比，有源PFC电路的输入电流接近正弦波且与输与电压同相位，能有效抑制电流波形畸变和谐波，因此避免了对同一电网设施的干扰。在PFC电路中，Boost变换器是研究和应用得最多的一种变换器。本文着重分析了Boost电路在不连续导电模式状态下，PFC电路的临界条件，对实际电路结构的设计有很好的指导意义。     

New two‐dimensional slope limiters for discontinuous Galerkin methods on arbitrary meshes

In this paper, we introduce an extension of Van Leer's slope limiter for two‐dimensional discontinuous Galerkin (DG) methods on arbitrary unstructured quadrangular or triangular grids. The aim is to construct a non‐oscillatory shock capturing DG method for the approximation of hyperbolic conservative laws without adding excessive numerical dispersion. Unlike some splitting techniques that are limited to linear approximations on rectangular grids, in this work, the solution is approximated by means of piecewise quadratic functions. The main idea of this new reconstructing and limiting technique follows a well‐known approach where local maximum principle regions are defined by enforcing some constraints on the reconstruction of the solution. Numerical comparisons with some existing slope limiters on structured as well as on unstructured meshes show a superior accuracy of our proposed slope limiters. Copyright © 2004 John Wiley & Sons, Ltd.     

露天矿山裂隙岩体爆破孔距变化的研究

文中指出裂隙岩体大孔距爆破在一点条件下与结构面的特性变化关系密切，并按两组三结构面建立了孔距计算公式。     

节理岩体的代表单元集合体模型及弹性参数预测

本文明确提出了节理岩体“代表单元集合体”的概念和模型，通过对节理岩体的“代表单元集合体”进行数值模拟，研究了节理岩体的“代表单元集合体”的变形特性，建立了节理岩体的弹性模型，提出了预测节理岩体宏观等效弹性参数的计算机模拟方法，并将其应用于岩体工程稳定性分析中。     

一种适合于同杆4回线的故障测距方法

在对同杆4回线解耦的基础上，提出了一种适合于同杆4回线的故障测距方法。同杆4回线内部发生故障时，可以将故障分量分解为12序分量，且利用该12序分量进行故障测距。考虑到在任何故障类型下，同杆4回线内部都会存在反序分量，所以提出了基于反序环流分量的故障测距方法。当同杆4回线内部发生故障时，从线路两端计算到故障点的反序环流分量电压相等，利用该关系可以求出故障点的精确位置。由于相互独立的12序分量完全能够解决线间耦合问题，文中提出的测距算法能够精确测距，测距精度不受故障类型影响。大量ATP仿真结果表明所提出的测距算法完全适用于同杆4回线的故障测距，测距精度不受过渡电阻、系统运行方式、线路两端功角的影响。     

CHARACTERISTICS OF INTERNAL FRICTION AND MODULUS ASSOCIATED WITH NON-EQUILIBRIUM DIFFUSION-TYPE PHASE TRANSFORMATION IN EUTECTOID Al-Zn ALLOY

The characteristics of the low frequency internal friction and the modulus effect associatedwith the non-equilibrium spinodal pretransformation and the following discontinuous trans-formation was investigated in an as-quenched eutectiod Al-Zn alloy.It was observed that theloss of the stability in the lattice,which corresponded to the large-amplitude long-wavelengthstatic concentration wave in the non-equilibrium spinodal pretransformation,did not induceany effect of localized soft modulus.Although there are two aging internal friction peaks inphase transformation which correspond to the appearance and disappearance of the coherencyin spinodal pretransformation and the maximum of the interface area in the discontinuoustransformation respectively,the effect of localized soft modulus did not take place yet.     

TiAl基合金在快速加热循环热处理过程中的结构失稳

观察了快速加热循环热处理过程中发生的4种结构失稳现象：形成二次层片组织、原始层片球化、晶界处非连续粗化、相界形核。通过比较连续加热与等温加热条件下的相转变开始线，探讨了连续加热与等温加热条件下结构失稳机制的异同。提出了快速加热循环热处理过程中避免结构失稳的途径：确保合金成分均匀，使各区域相变温度一致；使最高温度下的保温时间尽可能短。     

Interactive Simulation of Rigid Body Dynamics in Computer Graphics

Interactive rigid body simulation is an important part of many modern computer tools, which no authoring tool nor game engine can do without. Such high‐performance computer tools open up new possibilities for changing how designers, engineers, modelers and animators work with their design problems. This paper is a self contained state‐of‐the‐art report on the physics, the models, the numerical methods and the algorithms used in interactive rigid body simulation all of which have evolved and matured over the past 20 years. Furthermore, the paper communicates the mathematical and theoretical details in a pedagogical manner. This paper is not only a stake in the sand on what has been done, it also seeks to give the reader deeper insights to help guide their future research.     

基于广义Hoek-Brown准则的节理岩体力学参数折剪计算

节理化岩体力学参数是矿山工程地质和稳定性分析的重要基础数据,一般在实验室通过单轴、三轴试验只能得到岩石的力学参数,无法得到岩体的力学参数。目前,利用岩石力学参数确定岩体力学参数的方法较多,但都过于烦琐或准确度不高,急需一种新的简易确定方法。因此,通过利用基于广义Hoek-Brown准则的地质强度指标（GSI法）,并结合相应的岩土分析软件,强度折剪岩石力学参数值,从而得到岩体的力学参数。通过将该方法应用于赤峰中色白音诺尔矿业有限公司岩体力学参数的计算中,证明采用该方法考虑岩体的结构面和完整性,可较为准确地反映节理化岩体的力学特性,且方便可行,具有工程实用价值。?