Operational experience and recent developments at the National Medical Cyclotron, Sydney

The National Medical Cyclotron, Sydney, Australia commenced operation in mid 1991, with a mission to provide PET and SPECT radionuclides throughout Australia. The realization of the present production capacity has been synonymous with the development of the facility's industrial cyclotron (IBA Cyclone 30). The choice of cyclotron was based on the Cyclone 30's virtues as a compact, user-friendly, energy efficient cyclotron, offering the beam quality characteristic of negative ion technology. Development of the cyclotron has improved reliability and increased beam capacity, while improvements to targetry have increased production reliability. More recently, the installation and commissioning of a new solid target irradiation facility has provided much needed redundancy. This paper describes the major cyclotron and targetry developments carried out to date.     

日本关西宽带实验网印象

本文根据实地考察内容，结合宽带网络技术和业务重点及实施策略，全面介绍了日本关西宽带实验网发展背景，通信与广播电视综合应用实验和Ｂ－ＩＳＤＮ实用化实验的进展以及ＮＴＴ所起作用。文章最后就关西宽带实验网的借鉴意义提出了几方面意见。     

一种VSAT数据通信网络报文传输协议的分析

本文描述并分析了一种适用于多信道ＶＳＡＴ卫星数据通信网的报文传输协议，特别是考虑了无线信道误码率对传输协议的影响，分析表明利用Ｓ－ＲＥ－ＡＬＯＨＡ作为预订信道的多址方式及按报文占用数据信道方法可以减小报文传输延时并增加系统吞吐量。     

Influence of water and ammonia on hydrotreating catalysts and activity for tetralin hydrogenation

The effects of H₂O and NH₃ on the kinetics of the liquid phase hydrogenation of tetralin to decalin at 6.9 MPa and 330°C over commercial P---Ni---Mo/alumina catalysts in the presence of H₂S have been investigated. H₂O functioned as a mild kinetic inhibitor to an extent sensitive to the H₂S level. Quasi in situ XPS was used to investigate the catalyst structure after exposure to H₂0/H₂S.     

面向对象的设计特征与实现语言

在管理信息系统的开发以及分布式数据库系统的设计中，已开始使用面向对象的技术．本文论述了面向对象的设计特征，介绍了用于面向对象设计的各种实现语言，并着重分析了各种实现语言支特面向对象设计的能力．     

Mapping of Trellises Associated with General Encoders onto High-Performance VLSI Architectures

A rate 1/n binary generic convolutional encoder is a shift-register circuit where the inputs are information bits and the outputs are blocks of n bits generated as linear combinations on the appropriate shift register contents. The decoding of the outputs of a convolutional encoder can be carried out by the well-known Viterbi algorithm. The communication pattern of the Viterbi Algorithm is given as a graph, called trellis, associated to the state diagram of the corresponding encoder. In this paper we present a methodology that permits the efficient mapping of the Viterbi algorithm onto a column of an arbitrary number of processors. This is done through the representation of the data flow by using mathematical operators which present an inmediate hardware projection. A single operator string has been obtained to represent a generic encoder through the study of the data flow of free-forward encoders and feed-back encoders. The formal model developed is employed for the partitioning of the computations among an arbitrary number of processors in such a way that the data are recirculated opimizing the use of the processors and the communications. As a result, we obtain a highly regular and modular architecture suitable for VLSI implementation.     

用热分析法研究硝化棉的熔化过程

用ＭＤＳＣ，显微镜温台熔点测定仪和固体原位反应池／快速扫描傅立叶变换红外光谱联用装置考察了硝化棉的熔化过程。ＭＤＳＣ曲线表明吸热过程是可逆的，它系由ＮＣ和部分分解凝聚相产物的混合物的固液相变所引起。由ＮＣ的ＭＤＳＣ曲线得到的熔点，熔化含，熔化熵，分解含和分解反应热温熵分别为４７６．８４Ｋ，２０５．６Ｊ．ｇ＾－１，０．４３１２Ｊ．ｇ＾－１．Ｋ＾－１，－２４７５．０Ｊ．ｇ＾－１，－５．２４２Ｊ．ｇ＾－     

新型聚丙烯酸(934P、980)树脂的制备

详细研究了以乙酸乙酯和环己烷为溶剂，丙烯酸为单体，BPO，LPO，AIBN为引发剂，聚烯基多醚为交联剂，合成增稠能力强、透明度高的聚丙烯酸树脂。于混和溶剂存在下制得的聚合物，消除了以往由二氯甲烷为溶剂的反应介质中所得产品的毒性，可广泛应用于医药及日用化工等行业。     

A self-organizing fuzzy control of weld pool size in GMA welding processes

In arc welding processes, because of the complexity and nonlinearity of heat transfer phenomena, it is often difficult to design an effective control system based upon an exact mathematical model. In this paper, a self-organizing fuzzy control method is proposed to obtain a uniform weld quality by regulation of the surface temperature at a desired level. The proposed control system is designed to comprise a combined structure of the fuzzy SOC with conventional PD control for improving the system's stability. The control experiments show that the proposed controller guarantees a uniform weld quality for various welding conditions.     

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。