潜孔锤冲击作用下土体变形的有限元分析

潜孔锤冲击挤密钻进过程中周围土体的变形机理是一个高度非线性问题。针对潜孔锤在土中的面-面接触问题,运用Drucker-Prager屈服准则为判据,将土体视为DP材料,通过钻具与土之间的接触及施加冲击载荷来模拟钻进过程,从而建立了潜孔锤在土中冲击挤密钻进的有限元模型。利用非线性瞬态动力学有限元分析手段,对钻进过程中冲击力对土的作用加以研究,分析了钻具周围土体的应力、应变以及钻具与土体的摩擦情况。结果表明,在冲击载荷作用下,锥形钻头前端土体应力集中,并形成应力泡,冲击功主要用于竖向压缩土体,而水平方向的挤压作用相对较小,摩擦应力在钻头锥面附近出现峰值,是影响钻进速度的主要原因之一。     

Fixed collision rate back-off scheme for collision resolution in wireless networks

This investigation proposes a fixed collision rate (FCR) back-off algorithm for wireless networks. The proposed scheme takes advantage of the central unit (CU) in a wireless network to broadcast a common back-off window size to all the users, significantly alleviating the unfairness of bandwidth utilization in conventional binary exponential back-off (BEB) algorithms. It is shown that, when maximum throughput is achieved, collision rate is almost a constant for any traffic load. In the operation of the FCR, the CU dynamically adjusts the back-off window size to keep the collision rate at a constant level for maximum throughput. Simulation results demonstrate that the unfairness of bandwidth utilization in the BEB is significantly lessened and the throughput can be maintained at e^-1≈0.368 when the number of users approaches infinity. The capture effect even further improves system performance.     

The mirror effect and mixture signal detection theory.

The mirror effect for word frequency refers to the finding that low-frequency words have higher hit rates and lower false alarm rates than high-frequency words. This result is typically interpreted in terms of conventional signal detection theory (SDT), in which case it indicates that the order of the underlying old item distributions mirrors the order of the new item distributions. However, when viewed in terms of a mixture version of SDT, the order of hits and false alarms does not necessarily imply the same order in the underlying distributions because of possible effects of mixing. A reversal in underlying distributions did not appear for fits of mixture SDT models to data from 4 experiments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

外商直接投资对上海国内投资的挤出效应研究

建立了衡量挤入、挤出效应的数量模型，利用模型定量地讨论了外商直接投资(FDI)对上海国内投资的挤入、挤出效应，得到了外商直接投资对上海国内投资存在挤出效应的结论，并分析了产生挤出效应的原因。     

阳极炭块压降测试的方法与分析

本文通过阐述新的阳极炭块测试方法，提出了降低阳极炭块Fe-C压降的思路，并分析了降低阳极炭块压降对我公司经济效益的影响，可供同行参考。     

论普通型胶辊表面不处理的合理工艺参数

论述了普通胶辊表面不处理的性能特点和存在问题，技术措施和合理工艺参数，提高了成纱条干水平，减少缠绕和磨损。     

复杂信息处理中因果关联模型的构建及主因判定算法

近来，诸如图形图像、音频视频等复杂类型信息的分析和处理，已日益受到各学科领域专家和学者的重视，文章首先介绍了复杂信息处理中因果关联模型的构建，然后给出了主因分析方法的构造和实现过程，并提出了具体的算法和实例检验。     

时空效应规律在软土深基坑工程中的运用

阐述了时空效应规律在软土深基坑工程中的运用情况，实践证明，运用时空效应规律，能可靠而合理地利用土体自身在基坑开挖过程中控制土体位移的潜力而达到保护环境的目的。     

On the elemental effect of AlCoCrCuFeNi high-entropy alloy system

The AlCoCrCuFeNi high-entropy alloy system was synthesized using a well-developed arc melting and casting method. Their elemental effect on microstructures and hardness was investigated with X-ray diffraction, scanning electron microscopy and Vickers hardness testing. The alloys exhibit quite simple FCC and BCC solid solution phases. Co, Cu and Ni elements enhance the formation of the FCC phase while Al and Cr enhance that of the BCC phase in the alloy system. BCC phases form a spinodal structure during cooling. Copper tends to segregate at the interdendrite region and forms a Cu-rich FCC phase. Low copper content renders the interdendrite as a thin film and the as-cast structure like recrystallized grain structure. The formation of BCC phases significantly increases the hardness level of the alloy system. The strengthening mechanism is discussed.     

Anomalous Hall and Nernst Effects in Normal State of SC Cuprates

It is demonstrated that scattering of mobile charge carriers by fluctuations of local spin density in the normal state of SC-cuprates results in anomalous contribution to the transport phenomena (Hall and Nernst effects are included). Depending on their sign and magnitude, they can change value and sign of the corresponding effect measured.