Toughness enhancement and equivalent initial fracture toughness of cementitious composite reinforced with aligned steel fibres

Based on theoretical analysis and numerical simulation, the impact of steel fibres on the stress intensity factor (SIF) at the crack tip for cementitious composite was studied. The enhanced toughness of steel fibre reinforced cementitious composite (SFRC) in resisting cracks was explained by the decrement of SIF caused by steel fibre inclusions at the crack tip of the composite. The equivalent initial fracture toughness was used to characterize the crack initiation of SFRC. A simplified method for determining the of SFRC was proposed based on a linear regression method. Fracture tests were conducted on three‐point bending notched beams with different steel fibre volume fractions and specimen sizes to study the crack initiation behaviour of aligned steel fibre reinforced cementitious composite (ASFRC). of ASFRC was calculated, and the size effect of was analysed. The results showed that slightly increased with the steel fibre volume fraction and gradually became stable. For the tested specimens, whose heights varied between 40 and 100 mm, the specimen size had little impact on the .     

海上稠油油田蒸汽吞吐产量确定新方法

针对目前蒸汽吞吐产量预测模型假设条件简单、普适性差等问题,一般采用测试法和类比法综合确定海上稠油油田蒸汽吞吐初期产量。由于目前海上油田通常只开展常规测试,无法直接获得热采开发初期产量。笔者提出海上稠油油田蒸汽吞吐初期产量确定新方法,建立蒸汽吞吐相对于常规开发的初期产量倍数预测模型,通过蒸汽吞吐产量倍数,将常规测试确定的产量转化为蒸汽吞吐产量。研究表明,蒸汽吞吐初期产量倍数主要受储集层渗透率、原油黏度、注入强度、蒸汽干度等因素影响,利用正交试验设计和多元回归等方法,建立海上稠油油田蒸汽吞吐初期产量倍数与油藏地质参数及注入参数之间的非线性预测模型,该模型经实际生产数据验证,预测误差小于5%,可靠性高,能够为海上稠油油田蒸汽吞吐初期产量的确定提供依据。     

纺丝组件漏浆原因分析

通过对纺丝组件工艺对比调试,分析了纺丝组件消耗材料对纺丝组件漏浆的影响,指出了纺丝组件漏浆的主要影响因素。     

具有初始弯曲转子振动峰值的控制方法

本文从理论上研究了控制初始弯曲引起的转子振动幅值的一种新方法。通过在与转轴初始弯曲方向成较大夹角的方向添加不平衡质量的方法 ,使转子新的不平衡方向与初始弯曲方向夹角接近 180° ,则可以减小转子在临界转速附近的振幅。无论新的不平衡参数大于或小于初始弯曲参数 ,只要新的不平衡参数不至于太大 ,则临界转速附近的振幅响应肯定会得到改善。特别是当新的不平衡参数近似等于初始弯曲参数时 ,无论转速高低 ,振幅都会大幅下降。当重力参数、外阻尼系数和内阻尼系数改变后仍有同样结论。本文援引文献 [2 ]中的实例对这种方法进行了验证 ,并给出了解决类似故障的步骤。本文的方法可用于处理生产实际中转轴初弯引起的振动问题     

混合态二能级原子双光子过程中原子的压缩效应

本文采用时间演化算符方法和数值计算研究了相干光场与混合态二能级原子相互作用双光子过程中原子的压缩效应．结果表明：原子初始所处的混合态对原子压缩性质有较大的影响，当０．８５＜Ｓ＜１时，会周期性地呈现出短时的原子压缩效应，随着原子初始混合程度的增大，原子越来越远离压缩状态．     

小浪底水利枢纽的初期运行

总结了小浪底水利枢纽投运初期的水沙情况、孔板洞原型观测试验、调水调沙试验和枢纽的安全监测情况,介绍了大坝防渗、转轮裂纹问题的处理方案,总结了枢纽在防洪、防凌、减淤、供水和发电等方面发挥的作用。试验和对监测资料的分析表明,枢纽运行稳定,孔板洞设计合理、消能效果显著,各部位建筑物性态稳定,发挥了巨大的综合效益。     

On solving systems of ordinary differential equations on MIMD-computers

The error of solution of Cauchy problems for systems of ordinary differential equations is estimated in the case where the input data are approximate. It is shown how to prepare a program for computing the right-hand sides of the system automatically and simultaneously. Diagrams are presented to illustrate the efficiency of parallelization. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 175–182, March–April 2007.     

Choice With Initial and Terminal Link Reinforcement: An Alternative Self-Control Paradigm.

Self-control is demonstrated when a less desirable immediate outcome is chosen to ensure a substantially better future. In a novel animal analogue of this situation, primary reinforcement was delivered in both the initial and terminal links of a concurrent chain schedule. Rats made initial link choices between equal amounts of ethanol-free or ethanol-containing milk. Choosing the ethanol-free reinforcer resulted in delivery of the larger terminal link reinforcer and was thus analogous to self-control. Self-control decreased as the delay between initial and terminal links increased. The results have implications for human choice situations where decisions are made between two immediately available reinforcement alternatives each associated with a different delayed outcome. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

铀表面初始氧化行为的电子能量损失谱研究

利用俄歇电子能谱仪获取了表面清洁的铀及其在氧化过程中的电子能量损失谱(EELS)，研究这些电子能量损失谱线显示：清洁表面铀的等离子损失的实验值与理论值较为符合；随着氧化程度的加剧，体等离子体(BP)、表面等离子体(SP)以及价带间跃迁所造成的电子能量损失峰发生了明显的连续偏移和强度的变化，表明室温下清洁表面铀暴露微量纯氧后，在铀表面上发生了U→UO→UO2初始氧化过程。同时，又采用了俄歇电子能谱(AES)和X射线光电子谱(XPS)对照分析了铀的初始氧化过程。