一种计及分层效应的复合材料层合板疲劳寿命计算方法

给出了一种求解多向铺层复合材料层合板自由边层间应力的简化方法，并在此基础上提出了计及分层损伤的多向铺层复合材料层合板疲劳寿命的计算方法；算例与试验结果对比表明，该方法可以提高复合材料层合板疲劳寿命计算值与试验值的吻合程度。     

A determination method of initial camera parameters for coplanar calibration

Most coplanar calibration algorithms determine the initial camera parameters from a single image under the assumption that the principal point is known in advance. However, the camera orientations, the shifted principal point and the noise corrupted on images have an influence on the estimated initial camera parameters under the above assumption. This paper proposes a useful method to determine the initial camera parameters for coplanar calibration. The proposed method can determine the initial camera parameters from the single image, wherein the principal point is considered as a parameter. In our experiments, both synthetic and real images are used. The experimental results show that the proposed method provides both stable initial camera parameters and noise robustness for changes of camera orientations, noise levels and shifts of principal point.     

激光切割工艺参数的智能选择系统

提出用试验设计与人工神经网络相结合的方法,建立了一个激光切割工艺参数的选择优化的智能系统.通过试验设计的方法,只需做少数几次切割试验,将试验结果输入人工神经网络中进行训练和学习,系统便可经过自学得到切割结果与切割参数之间的隐含的定量关系,获得切割知识.在实际切割时,系统根据学到的切割知识,可以对任何给定的切割条件进行推理,对切割参数进行结果预测和优化.这种方法既不需要做大量的工艺试验,也不是单纯的专家经验,而是结合了两者的优点,使结果预测建立在既有试验数据又有专家知识的基础上,因而更加可靠、准确.该系统在激光方位切割的具体应用表明,系统能够准确给出定量的加工参数.     

基于高可靠性冗余环网通信的中压母线差动保护研究

本文介绍了一种基于高可靠性冗余环网通信的中压母线差动(简称"母差")保护技术,采用单间隔综合保护装置完成各自信息采集,将母差保护所需的信息通过环网发送至母差保护装置,母差保护动作后跳闸指令也通过环网到达各单间隔综合保护装置,在不增加电流互感器和接线的情况下实现母差保护功能.母差保护装置体积小、质量轻,可在断路器柜直接安装,测试表明,可以实现一个环网内30个间隔的母差保护功能.     

A new experimental technique for determinations of the activities of P<Subscript>2</Subscript>O<Subscript>5</Subscript> and Fe<Subscript>x</Subscript>O—the system CaO-P<Subscript>2</Subscript>O<Subscript>5</Subscript>-Fe<Subscript>x</Subscript>O

An experimental technique was applied for simultaneous determinations of the activities of P₂O₅ and Fe_xO in slags. With this technique, phosphorus-containing liquid copper was heated inside an iron crucible at temperatures below 1600 K. When copper is melted, the iron crucible dissolves into liquid copper, to a small extent, to form ternary {Cu-Fe-P} liquid alloy, while 〈Cu-Fe-P〉 solid solutions are formed on the inner wall of the iron crucible. Slags containing tri-calcium phosphate were then brought into equilibrium with {Cu-Fe-P} liquid alloy. By measuring the equilibrium oxygen partial pressures with the aid of a zirconia electrolyte cell, activities of P₂O₅ and Fe_xO were obtainable. Between 1553 and 1593 K, the P₂O₅ activities could be expressed as

层合效应与疲劳寿命

通过对T300／QY8911碳纤维／双马复合材料三类多向层压板共5种铺层方式板条的试验研究和理论分析,揭示出不同铺设相邻单向层之间良好的粘合是确保多向层板具有高抗疲劳特性的基础,但自由边区域高的层间应力将引起分层发生与扩展,它将严重降低层板的疲劳寿命。当主要受力方向确定时,层间应力的大小与铺设顺序有密切关系,合理设计铺设顺序是降低层间应力十分有效的措施。     

Extrusion of Metal–Ceramic Composite Pipes

Metal–ceramic composite pipes were prepared through simultaneous extrusion of different pastes by a multi-billet extrusion method. ZrO₂ and stainless steel powders were chosen, and an aqueous solution of water-soluble polymer, hydroxypropyl methylcellulose (HPMC), was used as binder. The maximum extrusion pressure and the minimum amount of binder required reached their lowest values when the mixing fraction of ZrO₂ powder was 0.4. The minimum amount of binder for forming the outer layers was 4%–5% higher than that for inner layers, even for the same powder. It was possible to decrease the binder content and broaden the extrudable range of the binder content by means of mixing coarse and fine powders.     

Analysis of creep behavior in thermoplastics based on visco-elastic theory

Plastics and fiber-reinforced plastics (FRP) are used in the aerospace industry because of their mechanical properties. However, despite their excellent high-temperature mechanical properties, plastics and FRP eventually deform visco-elastically at high temperatures. Most of the research has focused on the creep behavior of FRPs, but few studies have investigated the linear visco-elastic behavior. Linear visco-elastic behavior and non-linear visco-elastic behavior occur with physical aging in these plastics. In this study, the non-linear visco-elastic behavior of plastics and FRP was investigated based on the bending creep deformation of polycarbonate (PC) and polyoxymethylene (POM). Moreover, the effects of the fiber volume fraction on the creep characteristics were investigated using glass fiber-reinforced polycarbonate (GFRPC). The creep deformation was calculated using the linear visco-elastic theory based on these effects, and comparison between experimental and estimated data showed that the creep analysis sufficiently predicted the creep behavior.     

Low confinement loss hybrid-guiding tellurite photonic bandgap fiber

A hybrid-guiding tellurite (TZNLP) photonic bandgap fiber (PBGF) with low confinement loss is presented in this paper. A detailed comparison between the hybrid-guiding tellurite PBGF in which the high-index rods (TLWMN) replace one row of air holes in the radial direction and the all-solid tellurite PBGF has been accomplished. Low confinement loss windows can be achieved in this novel fiber due to the collaborated action of two guiding mechanisms–total internal reflection and antiresonant reflection.