计算机绘图中机器语言程序的应用

本文介绍在APPLE—Ⅱ机上,采用汇编语言程序,按磁盘道段直接存取信息,能充分利用外存容量,提高程序运行速度,并解决了计算机绘图中,运行大程序数据传递和复盖的困难.     

Investigation of the collapse of bubbles after the impact of a piston on a liquid free surface

A novel technique based on the impact of a piston on a liquid confined in a vessel is described. Pressure measurements reveal that strong pressure variations (up to 100 atmospheres) with a rich content of frequencies are efficiently transmitted to the liquid. High‐speed camera visualizations show that pre‐existing millimetric bubbles always collapse during the first instants of the impact whereas the behavior of submillimetric bubbles depends on the features of the pressure evolution in the system. In addition to the impact velocity, the amount of gas/vapor trapped between the piston and the liquid's surface plays an important role on how pressure evolves. Only when negative pressure occurs tiny bubbles grow significantly and collapse. The violent collapse of bubbles promote turbulence and mixing at very small length‐scales which renders this technique interesting to intensify processes limited by heat and mass diffusion. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2483–2495, 2017     

软弱破碎围岩深埋隧道拱顶渐进性塌方机理及控制

隧道拱顶塌方事故是近年来隧道施工中造成重大人员伤亡的主要事故类型,危害极大,因此必须掌握隧道拱顶塌方发生机理和演化规律、制定科学有效的控制对策,为塌方事故的防治提供依据。基于上限变分法,建立深埋地层中隧道拱顶塌方模型,研究隧道拱顶塌方范围及其影响因素,进一步建立软弱破碎围岩隧道拱顶渐进性塌方模型,推导渐进性塌方范围全过程曲线,并与模型试验结果进行对比。据此提出了拱顶塌方事故的安全性控制措施,揭示预控制、过程控制两类措施下拱顶塌方安全性控制机理和承载特性,提出支护措施的围岩荷载确定方法。结果表明：隧道塌方宽度L随着初始粘聚力c0和单轴抗拉强度σt的增大而增大,随着重度γ和非线性系数m的增大而减小;隧道塌方高度h1随着抗拉强度σt和非线性系数m的增大而增大,随着初始粘聚力c0和围岩重度γ的增大而减小;基于渐进性塌方过程中围岩物理力学参数逐渐减弱的特性,建立了考虑围岩粘聚力和抗拉强度衰减的隧道拱顶渐进性塌方模型;根据控制机理和目标,将拱顶塌方控制措施分为预控制措施和过程控制措施;围岩的形变荷载和总荷载随着塌方荷载的增大而增大。相关研究成果将为隧道拱顶塌方的预测及安全性控制提供借鉴。     

Research of Energy Deposition Caused by Pore Collapse

Mechanisms of energy deposition at the interface of particles in explosive compaction of metal powders are analyzed. A one-dimensional model of a spherically symmetric pore is proposed to reflect the collapse. The effect of heat conduction is taken into account in axisymmetric flow equations, and the temperature distribution during the sphere collapse is solved by the finite-difference method under the assumption that the material is rigid-plastic or thermoviscoplastic. The results show that the effect of heat conduction becomes more remarkable if the scale of the holes is small. During the collapse, the inner surface is converted from the elastoplastic to the fluid state, and its temperature becomes much higher than that of the remaining part of the sphere, which favors retaining of the amorphous structure in explosive consolidation of amorphous powders.__________Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 3, pp. 133–138, May–June, 2005.     

HEAT TRANSFER ANALYSIS FOR A VAPOR BUBBLE

In this work, we review the basic heat-transfer mechanisms of a vapor bubble immersed in an unbounded and subcooled liquid. The governing equations for the vapor and liquid phases, together with appropriate initial and boundary conditions, are presented in dimensionless form. In particular, if the characteristic inertial times are smaller than the characteristic process times, the evolution for the radius of the bubble depends basically on the Jakob number, Ja, and the vapor densities ratio, ρ. Recognizing that the Jakob number is very large compared with unity, the resulting governing equations are modeled by a thermal boundary layer, adjacent to the radius of the bubble. We show that higher order corrections due to curvature effects, associated with conductive and convective heat terms of the energy equation for the liquid, characterize the collapse of the bubble. For different values of Ja and ρ, the numerical results for the evolution of the nondimensional radius of the bubble,a, and for the corresponding nondimensional temperature profiles, θ, show that the ending collapse state has a singular behavior, which we have denoted as a “thermal runaway.”     

齿形件精冲成形时的齿顶塌角分析及措施

针对精冲成形齿形件时的齿顶塌角问题,首先分析了齿形零件的几何特征及精冲成形特点,并分析了这些特征与齿形零件精冲时齿顶塌角的关系;将精冲变形区分为2个核心变形区和2个变形影响区,对核心变形区Ⅰ精冲塌角的形成过程进行了分析。然后,通过有限元模拟软件Deform-3D,找出齿顶塌角处材料在成形过程中的流动规律。结果表明:齿顶处A面轮廓附近的材料沿齿顶径向运动,一部分材料流向齿顶外侧;齿廓B、C侧附近的材料沿其轮廓线所指向的齿顶方向流动。再次,全面分析了影响精冲齿顶塌角大小的各种因素,找出压边力和反顶力对塌角大小的影响规律,得出反顶力比压边力对控制塌角的效果更显著。最后,提出了在齿形零件精冲成形过程中减小或消除齿顶塌角的具体措施对策。     

热轧宽带钢塌卷缺陷的分析与控制

针对莱钢1500mm热轧宽带生产线生产部分品种规格时出现塌卷缺陷的问题,分析了卷取张力、带钢断面形状、卷取温度、卷筒涨缩、助卷辊辊缝设定对卷形的影响,并提出了相应的控制措施,取得了较好效果。     

阳春硫铁矿疏干及地表塌陷

广东省阳春硫铁矿矿区水文地质条件复杂,围岩富含岩溶水,为整治地下涌水,采取了一系列措施对井下和地表进行治理。详细介绍了生产疏干放水与地表塌陷的情况,对存在的问题提出了探索性建议。     

超高压水射流中空化现象对轮胎破碎作用研究

为了探讨超高压水射流破碎轮胎过程中,冲击波和微射流的作用机理,基于FLUENT软件环境,采用VOF模型求解Navier-Stokes方程,数值模拟了近壁面的空泡溃灭过程,结果表明,射流冲击物面时,空泡溃灭产生的压力脉冲远大于微射流产生的冲击压力。结合超高压水射流破碎轮胎试验,通过对胎面胶的切槽断面形貌进行观察,研究了微射流和冲击波对橡胶材料的破坏作用,认为橡胶材料在受到空化作用破坏时,表现出明显的冲击脆化现象,微射流在材料壁面冲击出边缘齐整的针孔状形貌,冲击波引发材料产生拉伸破坏。     

荔浦市岩质崩塌形成条件及失稳运动特征

通过对荔浦市境内碳酸盐岩区岩质崩塌及该区域地质环境条件的调查,总结了岩质崩塌的规模、发育高度、控制结构面等发育特征,分析了岩质崩塌形成条件,并判断岩质崩塌的失稳运动特征.本文以一处危岩为例,用无人机进行三维扫描并分析其形成原因及预测其失稳运动特征.