A new method of preform design in hot forging by using electric field theory

The preform design in metal forging plays a key role in improving product quality, such as ensuring defect-free property and proper metal flow. In industry, preforms are generally designed by the iterative trial-and-error approach. This approach, however, leads not only to the increase of significant tool cost but also to the extended down-time of the production equipment. It is thus necessary to reduce time and man power through an effective method of preform design. In this paper, the equi-potential lines designed in the electric field are introduced to find an appropriate preform shape. The equi-potential lines generated between two conductors of different voltages show similar trends for the minimum work paths between the undeformed shape and the deformed shape. Based on this similarity, the equi-potential lines obtained by the arrangement of the initial and final shapes are utilized for the design of the preform, and then the artificial neural network is used to find the range of initial volume and potential value of the electric field.     

多频电磁波测井数据的反演成像技术及应用

针对测井数据反演成像问题的不适应定性，采用了带不等式约束的正则化最小二乘迭代反演，模型响应的正演计算用有限元方法实现，模型响应对电阻率及介电常数的偏导数用格林函数和互换原理计算，对高低频电磁波测井数据的反演分两步进行，首先用低频数据得到电阻率的大致分布，再以此为初值，用高频电磁波数据同时反演电阻率和介电常数，通过对模型的数值模拟和某地热田1口井的实际资料的应用表明，电磁波测井数据的反演厉像能给出井周近旁介质的电性参数分布，而在离井较远的区域不能得到稳定可靠的解释结果，无论高频还是低频测井数据，要得到高质量的成像结果，工作频率的适当选择及接收器灵敏度的提高是至关重要的。     

列车对半圆拱形隧道中电磁波截止频率的影响

在空隧道中电磁波存在着截止频率，列车的存在改变了隧道的截面形状和尺寸，从而影响了电磁波的截止频率。应用有限元方法研究了煤矿井下巷道中列车的高度，宽度和位置对半圆拱形隧道电磁波截止频率的影响，其结果对铁路隧道，公安隧道等有限空间的无线通信也具有重要的意义。     

一种测定深部岩体地应力的新方法——钻孔局部壁面应力全解除法

简要回顾了基于钻孔进行地应力测量的几种方法，并指出了这些方法自身存在的局限性。提出了一种测定深部岩体地应力的新方法-钻孔局部壁面应力全解除法。该方法的明显优点是，不需要套钻，而且在确定地应力的主值及其方向时也不需要作任何假定。从理论上讲，该方法将不受测量深度的限制，对于深钻孔是普遍适用的，这将为大陆科学钻探计划中深部岩体地应力测量提供一种新途径。     

AlSn20Cu/Steel双金属板(带)复合轧制过程的厚度匹配

通过对AlSn20Cu/Steel双金属板(带)复合轧制过程变形区变形规律的分析，确定了轧制过程的总变形率与各分层变形率的关系，解决了实际生产中各分层原料的厚度匹配问题。     

次生伽马能谱分析方法的实验研究

本文指出一种地化学闭合模型的热中子瞬发活化伽马分析方法，它是地球化学测井的核心技术，标准谱的获得，基于标准谱的加权最小二乘解谱方法、灵敏度刻度及地球化学闭合模型是这一方法的关键环节。     

挤压六通管及其连接结构的安全性研究

六通管是石油化工设备及压力管道中的重要元件,传统的制作及连接方法是在集流管上开孔,然后将支管插入并焊接而成或采用锻制的方法制成。采用挤压的方法制作六通管,将其与支管对接焊接。并通过试验及数值模拟对该结构的安全性进行了研究,实践证明,这种挤压六通管的强度性能优于普通的焊接六通管,可以广泛应用于工业生产。     

螺栓球网架杆件在非节点横向荷载作用下承载力的有限元分析

运用ANSYS有限元程序 ,研究了在轴向力与非节点横向力共同作用下网架螺栓球节点杆件的受力性能 ,得出其应力分布状况及弹性极限承载力 ,并提出了螺栓球网架杆件在非节点横向力作用下承载力的计算公式。     

刚体极限平衡法与有限元法在工程边坡稳定性分析中的应用与比较

刚体极限平衡法、有限元法在工程边坡稳定分析中是两个常用的计算方法,文中对两种方法的理论基础和计算过程进行了简要介绍,并应用两种方法对一工程实例进行了分析。结果表明,二者的计算结果相近,且相同工况下有限元计算安全系数略小于刚体极限平衡法计算安全系数。     

Drying of Chestnuts (Castanea sativa Mill.) after Osmotic Dehydration with Sucrose and Glucose Solutions

Chestnuts were dehydrated by using a combined method of osmotic dehydration followed by air drying. Samples were osmotically pretreated with sucrose (60% w/w) and glucose (56% w/w) for 8 h, air-dried at temperatures of 45, 55, and 65°C, at a relative humidity of 30% and at a velocity of 2.7 m·s^-1 and the experimental data of the drying kinetics were obtained. Whole samples were dried with different peelings: (a) removal of endocarp and pericarp (peeled) and (b) additionally the internal rough surface (cut). In all cases, cut chestnuts show greater drying rates than peeled samples, indicating that a significant mass transfer resistance in the layer nearest to the surface takes place. Peeled samples pretreated with sucrose solutions behave in a similar way to untreated samples. For the rest of the samples, the cut samples osmotically treated with sucrose solutions and all the samples treated with the glucose solution, the drying rates decrease during drying. Drying kinetics are successfully modeled by employing a diffusional model that takes the shrinkage into account. The effective coefficient of water diffusion was evaluated and correlated with temperature. The quality of the final product was monitored by color change. In spite of the fact that the total color difference is not modified by the osmotic treatment, the L*, a*, and b* color coordinates of cut samples treated with sucrose and glucose solutions do undergo changes; the L* and a* coordinates change less than the b*.