Impact Initiated Annular Retonation Wave in explosive

Experiments conducted at the White Oak Laboratory with a pentolite explosive charge impacted by a flat-ended cylinder of mild steel, showed a hole drilled at the center of the impactor, if the explosive was detonated. A computer simulation was carried out with the finite element hydrocode DEFEL and the Forest-Fire reaction-rate model. Computed results verified the hypothesis that the annular retonation was the cause of the drilled hole. The detonation started at a distance of about 10 mm from the impact surface, then developed into an annular shape and propagated inwards and backwards, to the axis of symmetry and the impact surface. The converging wave generated a pressure of about 100 GPa near the center of its impact surface, which is believed to be the real cause of the hole.     

Retonation Wave upon Shock-Wave Initiation of Detonation of Solid Explosives

An original photograph of a retonation wave is presented; the wave arose spontaneously in a charge of a 20/80 nitroglycerine/ammonium nitrate mixture with a density of 0.9 g/cm³ at a distance of 0.8 of the charge length and went back half of the charge length toward the place of initiation. The velocity of the forward wave was 2300 m/sec, and the velocity of the retonation wave was 1700 m/sec. The retonation wave was registered only in one, unique experiment. Key words: initiation, detonation, retonation wave, velocity, nitroglycerine, ammonium nitrate.     

稠油蒸汽吞吐加热半径与动用半径关系研究

正确确定稠油油藏的加热半径和动用半径,是油藏确定井距、制定调整措施的基础。基于能量平衡方程和稠油非达西渗流理论,分别对稠油的加热半径和动用半径进行了计算,得到了多轮次注汽后,不同油层厚度下注汽量和加热半径关系和不同流度与动用半径关系,计算的动用半径与现场实测情况相近。在此基础上,得到了加热半径、动用半径随流度的变化模式,确定了不同油藏类型的最小井距。     

Detonation Velocity Deficits and Curvature Radius of Mild Detonation Cords

In order to study the detonation velocity deficits of wound mild detonation cords, a physical model and a theoretical mathematical equation for detonation velocity deficits of wound mild detonation cords were established based on the detonation wave’s corner effects and delay time phenomenon by using non‐dimensional analysis method. Besides, a semi‐empirical formula for detonation velocity deficit of wound mild detonation cords in the same charge size was obtained through experiments and curve fitting. Both the theoretical mathematical equation and the semi‐empirical formula show that the detonation velocity deficit of wound mild detonation cords and the reciprocal of the curvature radius have an exponential relationship.     

高端艺术与乡土民艺的距离

高端艺术和乡土民艺之间并没有不可逾越的鸿沟,甚至可以说,两者之间本无距离。一幅蓝底的图画,画面由大小不同的白点组成星河,飘渺、神秘;斑驳的土墙上,白色的鞋垫组成花环,鞋垫上的白色刺绣纹样闪烁着迷人的光辉……北京荔空间,一场别开生面的艺术展＂天堂＂吸引着中外观众：《在那遥远的地方》、《活着》、《我的书》、《家》和《我们》五组作品全部由宁夏当地的绣花线、羊皮等材料制作,呈现着当代艺术和传统手工艺巧妙嫁接带来的视觉冲击和观念嬗变。这些作品均出自一个叫＂艺术扶贫计划＂的项目,     

聚合物发泡泡孔尺寸调控

采用核壳模型建立了描述聚合物发泡泡孔增长过程的一组控制方程，并采用有限元法而不是通过浓度边界层的积分对控制方程组进行了求解；同时考察若干影响最终泡孔尺寸的因素。计算表明对于一具体发泡过程壳层厚度主要影响最终泡孔尺寸。     

超高压管式反应器的最佳弹性-塑性交界面半径

应用Mises屈服条件,考虑温差应力对超高压管式反应器疲劳寿命的影响,从剪应力强度最小原理与剪应力强度均匀分布原则,分析得到最佳弹性-塑性交界面半径公式,结果表明剪应力强度最小原理和剪应力强度均匀分布原则是相容的。文中公式可供超高压管式反应器的工程设计参考。     

短半径厚壁弯头成型工艺研究

短半径弯头成形变比很大,故采用两次热压方式成形,本文采用新钢种A335P92,介绍了其加工性能并对原来使用的厚壁弯头热压成形工艺提出了改进方法,改进后的厚壁弯头热压成形工艺具有减少模具制造成本、成形操作简单、降低劳动强度和提高成形质量的优点。     

带式输送机凹弧段曲率半径的非标设计

针对老厂改造中经常遇到的带式输送机因受场地和工艺条件的限制而无法布置的情况,介绍带式输送机凹弧段曲率半径的非标设计方法。着重叙述了如何确定凹弧段曲率半径,半提出了防止带式输送机空载起动时输送带脱离托辊的措施。实践证明,该非标设计方法是可行的,可供类似的技术改造项目参考。     

浅水爆炸对破坏半径的影响

水中兵器装药在离水面比较近处爆炸,由于自由面的影响,其装药的有效破坏半径减小,毁伤效能降低。现采用1kgTNT当量药包,进行浅水爆炸试验;应用最小二乘法、冲量等效、能量等效方式处理p（t）关系式,得到二种有效破坏半径的计算公式：Rs＝0．7636R＋0．2603H;Rs＝0．9301R＋0．1047H。     

Friction Coefficient and Mobility Radius of Fractal-Like Aggregates in the Transition Regime

The influence of geometric properties and particle size on mobility properties of fractal-like aggregates was studied in the mass and momentum-transfer transition regimes. Two methodologies were investigated. The Collision Rate Method (CRM) that determines the slip correction factor through the ratio of two fictitious Brownian particle-aggregate effective collision rates, and the Adjusted Sphere Method (ASM) that assumes the existence of a virtual, flow-independent adjusted sphere with the same slip correction factor as the aggregate over the entire transition regime. The simulated fractal-like aggregates were synthetic as they were generated via a cluster–cluster agglomeration algorithm. The CRM was used to calculate the adjusted-sphere radius of various aggregates: we found it to be weakly dependent on the monomer Knudsen number for Kn greater than 0.5. Numerical expressions for the aggregate orientationally-averaged projected area and the adjusted-sphere radius are proposed. Both expressions depend on geometric, non-ensemble averaged quantities: the radius of gyration and the number of monomers. The slip correction factor and the mobility radius of DLCA and RLCA aggregates were calculated using the ASM: for a given number of monomers, fractal dimension and prefactor, and Knudsen number their values were approximately constant (averaged over aggregate realizations). A fractal-like scaling law based on the mobility radius was found to hold. The mobility fractal dimension and prefactor were determined for different aggregates. The hydrodynamic radius, proportional to the friction coefficient, and the dynamic shape factor of DLCA and RLCA aggregates were also calculated.     

二氧化碳储罐物理爆炸能量及波及半径的定量评价

运用高压气体爆炸能量计算公式,二氧化碳储罐物理爆炸能量及波及半径进行定量评价,计算出损伤半径,为装置的安全管理提供依据。     

喷射流扩展半径及喷射火后果模拟计算方法研究

根据喷射能量守恒关系推导出喷射流扩展口半径计算式,该表达式体现扩展半径与泄漏口半径、喷射物密度之间的关系。采用HSE（Health and Safety Executive）的MHAU（Major Hazards Assessment Unit）程序中的通用喷射火模型程序SHELF2案例验证文章推导的扩展半径计算式代入API喷射火模型模拟计算喷射火的准确性,结果表明文章中的模拟方法能较准确地模拟喷射火,模拟计算结果符合L.T.Cowley总结CEC（Commission of European Communities）实验数据得出的结论。     

环隙式离心萃取器界面半径的测定与关联

采用“快速放液法”测定转筒内的存留量，并用合适的相分布模型计算出相应的界面半径，即实验值。系统研究了转速、流比、重相堰直径、流量、两相密度差和粘度６个参数对环隙式离心萃取器界面半径的影响。用多元回归关联了６个自变量，拟合了界面半径的经验公式。计算值与实验值吻合较好，平均误差３．０３％，可用来确定２０ｍｍ环隙式离心萃取器最佳工作条件。     

喉道半径与可动流体对低渗透储层渗流性的影响

渗流性能是储层评价的一个重要方面。本文在前人研究的基础上,深入研究了低渗透油田中喉道半径、可动流体百分数与储层物性之间的关系,指出喉道半径、可动流体百分数是影响低渗透储层渗流性能的重要因素。对大庆外围低渗透油田的开发具有一定的指导意义。     

大口径小曲率半径高难度顶管施工技术和质量控制

大口径小曲率半径曲线顶管施工具有较高的施工难度。该文以上海地区首例雨水管道Φ2 400顶进泵工程为例,介绍了某改进型泥水机械平衡式顶管机作为关键设备用于该工程,总结了该项目施工的技术要点与注意事项,以其为相关大口径小曲率半径顶管工程的施工提供参考。     

钻井液完井液侵入半径预测新模型

油气田开发时,需要使用钻井液钻开油气层,形成渗流通道,建立油气井的良好生产条件.然而,外来流体由于所包含的化学剂及本身的流变性和人工操作方面的原因,在进入地层时会造成地层伤害,使岩石结构和表面性质改变,甚至引起储集层润湿性和流体相态的改变,导致井筒附近地层渗透率下降,增加油气流流向井筒的阻力,使产能和注入量下降.因此,本文从地层伤害的基本原理出建立了一种新的钻井液滤失模型.     

成人现代远程教育：问题与建议

现代远程教育是利用网络及多媒体技术等现代信息技术手段开展的新型教育形态,随着信息技术的发展,现代远程教育已经越来越普及,它使学习方式变得灵活,为在职人员获取知识,成年人终身学习及学习型社会的构建提供了支持。本文分析了成人现代远程教育的现状及存在的问题,并据此提出了发展我国成人现代远程教育的几点建议。