纤维复合材料在预应力混凝土结构中的应用

近年来，纤维复合塑料材料作为钢筋和预应力钢筋被日益广泛就应用于预应力混凝土结构，文中对国际上这一新技术研究和应用情况进行一些介绍和讨论。     

Monel合金高速塑性剪切变形与动态再结晶

采用Ｈｏｐｋｉｎｓｏｎ杆加载技术和帽状试样，研究Ｍｏｎｅｌ合金在εｓ≈４．３×１０５ｓ－１的高应变速率条件下的应力－应变关系及塑性变形行为．实验及计算结果表明，塑性区（简称剪切带）内温度随剪切应变增加呈线性升高．透射电镜证实剪切带组织发生了动态再结晶，再结晶晶粒约为１７０ｎｍ．分析了剪切带中组织结构的演变过程，讨论了动态再结晶的机制     

Three-dimensional rigid–plastic finite element analysis of non-steady-state shaped drawing process

In this paper, non-steady-state shaped drawing processes have been investigated by using the three-dimensional rigid–plastic finite element (FE) method. In order to analyze the shaped drawing process, a method to define a straight converging die by considering a straight die part, a die radius part and a bearing part has been proposed. In addition, the modeling of the initial billet and the generation procedure of the mesh system have been suggested. The three-dimensional rigid–plastic FE simulation has been performed for a square sectional drawing process and its validity has been confirmed by comparison with existing experimental results. Under the same process conditions, the effect of perimeter ratio and drawing stress in the shaped drawing process has been investigated. Also, the effects of process variables, such as the reduction in area and semi-die angle, on drawing stress and corner filling in the drawing process of a square rod from a round bar have been investigated by using the rigid–plastic FE code developed. In order to investigate corner filling, the diagonal ratio is calculated and compared with the results of the FE simulations. Furthermore, limits of the process variables are determined by considering bulging and necking. From the results, an optimal process condition satisfying reasonable corner filling and a minimum value of drawing stress is suggested.     

射水法建造薄型塑性混凝土防渗墙在向阳水库除险加固中的应用

射水法建造塑性混凝土防渗墙,是近十生年来才发展并日趋完善的建造地下连续墙的新工法.该工法具有工艺合理,工序衔接紧密,设备配套完整且自成系统,适应地层范围广,成墙垂直精度高,施工布置灵活,事故处理难度小及造墙性价比高等显著优点.本文通过该技术在向阳水库除险加目中的应用,介绍射水法建造塑性混凝土防渗墙施工工艺及施工中应注意的一些问题.     

数控铣削加工中刀具补偿的应用

阐述了如何利用刀补原理,来正确、快捷的编制铣削加工程序,以保证数控铣削加工程序的有效性和加工零件的精确性。     

A Study of Effective Deployment in Ultra-Low-Permeability Reservoirs With Non-Darcy Flow

Abstract

Due to the existence of a threshold pressure gradient (TPG) in ultra-low-permeability reservoirs, the peripheral reserves of the wellbore are difficult to deploy effectively. The main problem is that it is hard to ensure that well pattern, well spacing, and drawdown pressure easily and accurately because of the existence of low-velocity non-Darcy flow in such reservoirs. Simple and accurate calculation methods of the problem are most popular with reservoir engineers, so effective deployment calculation methods of ultra-low-permeability reservoirs are presented in this article. They include control radius calculation, control distance calculation, control area calculation, and control coefficient calculation, which can be directly used in the evaluation of well pattern thickening of developed oilfields and reserves of undeveloped oilfields. Based on theory of fluid mechanics in porous medium considering TPG, the non-Darcy flow mathematic model was established to reveal the characteristics of pressure distribution of ultra-low-permeability reservoirs. According to the analytical solution of non-Darcy radial flow, the relationship between control radius for ultra-low-permeability medium and TPG under different drawdown pressures was established. A calculation method combined with ellipse flow theory for control coefficient is presented, which was used to characterize the producing degree of reserve in a rectangular pattern. The control radius and coefficient of ultra-low-permeability reservoirs can provide a theoretical foundation for reservoir evaluation and development design.     

新型镶嵌式催化剂挤条成型装置的研制

介绍一种新型镶嵌式组合结构催化剂挤条成型装置。新型镶嵌式催化剂挤条成型装置的模架为不锈钢材料,镶嵌模块采用工程塑料,模块更换方便,催化剂挤出顺畅,能满足石化行业催化剂挤条生产中耐温、耐压、耐腐蚀以及规模化生产的要求。与不锈钢整体结构挤条模板相比,新型镶嵌式催化剂成型装置不仅成本降低较大,而且制作周期缩短。     

带有螺纹塑料件的自动退扣模具设计

通过分析内、外表面带有螺纹的塑料件结构,阐述带有螺纹的塑料件的设计特点,对分型面的选择、型腔数目的确定、浇注系统以及推出机构的设计进行了讨论.确定推出机构采用齿轮、齿条自动退螺纹的模具结构.此模具结构简单,成本低,可确保产品质量,适用于批量生产.     

Enzymatic interesterification of lard and high-oleic sunflower oil with Candida antarctica lipase to produce plastic fats

Lard and high-oleic sunflower oil (Trisun® Extra) were interesterified at 55°C for 24 h with SP435 lipase from Candida antarctica to produce plastic fats. As the amount of trisun increased, percentage free fatty acid, unsaturated fatty acid/saturated fatty acid value, oxidizability, and the amount of 18:1 found at the sn-2 position of triglyceride products increased. Differential scanning calorimetry showed that the low-melting components in the product contained more 18:1 than the high-melting components. A 60:40 (w/w) ratio of lard to trisun had the widest plastic range (3–26°C). The scaled-up reaction to produce this blend resulted in a product that had 60.1% 18:1 at the sn-2 position compared to 44.9% for the physical blend. The solid fat content of the 60:40 interesterified mixture resembled soft-type margarine oil.     

基于改进空间正则化相关滤波器的运动目标跟踪研究

为降低光照、遮挡、尺寸变化等因素对目标跟踪过程的影响,提出在经典空间正则化核相关滤波基础上,增加遮挡检测及处理机制,并分别采用相似度计算与空间距离计算作为遮挡评判标准。在模型更新之前先判断遮挡是否存在,如有遮挡,则不更新模型;否则更新模型。提出搜索半径择优处理,分别以6种搜索半径进行目标跟踪,寻找最优搜索半径;进而提出特征择优处理,分别提取HOG特征、PHOG特征、Haar-like特征、LBP特征以及FHOG特征与改进算法结合,选取最佳特征。采用两组实验进行验证:分别采用经典KCF算法、Mean Shift算法、Fragment算法、DSST算法、经典SRDCF算法和改进SRDCF算法对Bolt2和Basketball两个视频中运动目标进行跟踪对比。实验结果表明:FHOG特征与改进空间正则化核相关滤波相结合,且在搜索半径为8个像素点时的跟踪性能最佳,优于其他经典跟踪算法,处理速度可达3. 7 fps。