Estimation of the resident’s additional dose in bone-coal mining areas of the five provinces

1 Introduction In the National Investigation of Natural Radioac-tive Levels (abbreviated as “investigation of levels” hereinbelow) during 1983 to 1990, it is found that the specific activities of radionuclides in bone-coal are relatively high. The increase of radioactive level in the environment and the rise of the public accepted dose might be caused by some artificial activities, which include mainly mining and utilizing spontaneously bone-coal by local peasants, producing bone-coal cind…     

Explicit local buckling analysis and design of fiber–reinforced plastic composite structural shapes

Pultruded fiber–reinforced plastic (FRP) composite structural shapes (beams and columns) are thin-walled open or closed sections consisting of assemblies of flat plates and commonly made of E-glass fiber and either polyester or vinylester resins. Due to high strength-to-stiffness ratio of composites and thin-walled sectional geometry of FRP shapes, buckling is the most likely mode of failure before material failure. In this paper, explicit analyses of local buckling of rectangular orthotropic composite plates with various unloaded edge boundary conditions (i.e., (1) rotationally restrained along both unloaded edges (RR), and (2) one rotationally restrained and the other free along the unloaded edges (RF)) and subjected to uniform in-plane axial action at simply-supported loaded edges are first presented. A variational formulation of the Ritz method is used to establish an eigenvalue problem, and explicit solutions of plate local buckling coefficients in term of the rotational restraint stiffness (k) are obtained. The two cases of rotationally restrained plates (i.e., the RR and RF plates) are further treated as discrete plates of closed and open sections, and by considering the effect of elastic restraints at the joint connections of flanges and webs, the local buckling of different FRP shapes under uniform axial compression is studied. The approximate expressions of the rotational restraint stiffness (k) for various common FRP sections are provided, and their application to sectional local buckling predictions is illustrated. The explicit local buckling formulas of rotationally restrained plates are validated with the exact transcendental solutions. The analytical predictions for local buckling of various FRP profiles based on the present discrete plate analysis and considering the elastic restraints of the flange–web connections are in excellent agreements with available experimental results and finite element eigenvalue analyses. A design guideline for local buckling prediction and related performance improvement is proposed. The present explicit formulation can be applied effectively to determine the local buckling capacities of composite plates with elastic restraints along the unloaded edges and can be further used to predict the local buckling strength of FRP shapes.     

锅炉燃烧器模糊-PID复合控制器的设计

将模糊-PID复合控制器应用于锅炉燃烧器控制器的设计中，许用C8051F020 MCU及其外部接口电路来实现控制。从仿真结果表明，使用这种模糊-PID复合控制器可以获得很好的控制效果。     

图像编码中的容错方法分析

随着信息社会的到来,互联网以及正在迅速发展的移动通信技术,逐渐成为人们获取信息的中心。而这些信息的传输都必须由具有较强鲁棒性的压缩数据来保证。所以,在有干扰的信道中如何保护传输的压缩数据不受干扰成为人们关注的问题。针对现代信息中的最主要的图像数据的传输问题,对一些差错控制方法,特别是在JPEG2000及MPEG-4标准中所采用的新的容错工具和方法进行了较详细地分析。     

电力电容器的相控技术

讨论分析了电力电容器连续相控（ＴｈｙｒｉｓｔｏｒＣｏｎｔｒｏｌｌｅｄＣａｐａｃｉｔｏｒ）ＴＣＣ新技术。其中主要阐崐述了ＴＣＣ技术的工作原理、波形分析结果和谐波抑制方法。     

杆板结构系统的可靠性分析

提出一种可模拟飞行器翼面等薄壁结构的杆板结构系统的可靠性分析方法，导出在Ｍｉｓｅｓ屈服条件下平面应力元件的完全裕量方程。     

高精度七米激光测长机的误差补偿技术

简要介绍一笔者研制的大型计量测试仪器－“高精度七米激光测长机及其计量管理系统”的工作原理，详细地介绍了其测量过程中采用的误差补偿技术并进行实验验证。     

基于边界表示的曲面实体造型系统的数据结构

实体造型是ＣＡＤ系统的核心模块，而二次曲面在工程中常用来描述轴，孔及圆角等形状特征。讨论了在微机上实现的一个基于边界表示的实体模型的数据结构，并针对二次曲面的特点，实现了对自封闭曲面的无二义性拓扩定义，为顺利进行曲面的拼合运算打下了基础。     

A flexible and recoverable client/server database event notification system

A software architecture is presented that allows client application programs to interact with a DBMS server in a flexible and powerful way, using either direct, volatile messages, or messages sent via recoverable queues. Normal requests from clients to the server and replies from the server to clients can be transmitted using direct or recoverable messages. In addition, an application event notification mechanism is provided, whereby client applications running anywhere on the network can register for events, and when those events are raised, the clients are notified. A novel parameter passing mechanism allows a set of tuples to be included in an event notification. The event mechanism is particularly useful in an active DBMS, where events can be raised by triggers to signal running application programs. Received July 21, 1995 / Accepted May 30, 1996