低工作温度的氧化钨气敏材料

本文报道了一种可以在１００℃左右工作的氢化钨气敏材料，它对氢气和一氧化氮有很高的灵敏度和良好的选择性，并可对空气中的一氧化氮进行探测     

CODAS在CAI中的应用研究

控制系统的设计与仿真是着眼于充分掌握和运用反馈控制系统原理的非解析课件。控制系统的设计与仿真实验课作为广东机械学院计算机辅助教学的一部分已经在Ｎｏｖｅｌｌ局域网上开出．该课程的各种练习、例题、问题及实例教学鼓励学生自测和开发他们所学的知识．是特别适合自学的控制系统计算机辅助教学课程。     

Towards a consolidated model for a collaborative courseware authoring system

Abstract In an effort to reduce the expensive resource requirements in courseware production and to allow effective management of, and communication and collaboration between authors, a model is needed to harmonize the diverse theoretical backgrounds such a process requires. To this end we look at five abstract models which where chosen for their apparent appropriateness within the general area of collaborative authoring and reuse of multimedia courseware. These models consist of a functional model of hypertext, an infrastructure model for an open collaborative authoring system, two object-oriented communication models, and a courseware production model. We attempt a consolidation of these models and ultimately make several conclusions, which are exposed during a conceptual harmonisation. The principal conclusion is that a hypermedia logical model is not by itself adequate to support collaboration and reuse. Our modeling conclusions have driven the design of a system which will be implemented and tested.     

旋转式伽玛刀的辐射剂量学

旋转式伽玛刀的辐射剂量学指标的物理测试在放射性医疗设备投放医院正式临床使用前是必不可少的，是对设备及其附件的设计、加工制造、安装以及电气控制系统等的全面综合性检定。用电离室作辐射剂量学的绝对测量，用胶片法进行相对测量，给出了测量结果并进行了讨论。     

Modeling and design of an AC to DC converter

A step-up/down single-phase AC-to-DC power converter without current sensor is proposed to achieve high performance and simple control logic. The power converter adopts a front-end diode rectifier so that only one active switch is required. The familiar state-space averaging technique for discontinuous mode DC-to-DC power converters is extended to model the proposed AC-to-DC converter. Unlike the existing model, which is valid only for a very low frequency range, namely below line frequency, the proposed model is applicable up to half switching frequency. The design of the controller is detailed. Selected experimental results are presented to verify the proposed theory     

北京谱仪Ⅱ（BESⅡ）顶点探测器数据获取系统

北京谱仪（ＢＥＳⅡ）顶点探测器数据获取系统是北京谱仪数据获取系统的一部分，该子系统电子学采用快总线标准，本文描述了该系统的硬件结构和软件系统，软件包括快总线系统的微码软件和上层控制软件，该系统的死时间为１．５ｎｓ，对ＢＥＳⅡ系统总死时间的贡献小于０．５ｍｓ。     

Evaluation of Soybean Seedcoat Cracking During Drying:PART II. Using MRI

MRI techniques were developed and employed for non-destructive and noninvasive study of seedcoat cracking in low moisture soybean kernels during heated air drying. Proton density image and transient moisture distribution profile of a single soybean kernel can be obtained using MRI. These MRI techniques proved to be particularly useful for the continuous observation of initiation and propagation of seedcoat cracking during the entire period of drying process without interruption.

The proton density images of soybean kernels showed that seedcoat cracking was initiated perpendicular to the long axis of the kernel near the hilum. The transient moisture distribution profiles in soybean kernels during drying indicate that moisture gradient developed during drying was higher in the seedcoat than in the cotyledon. Drying temperature and initial average moisture content were positively correlated with the soyhean seedcoat crackig. The location of the