基于控制器局域网络的γ辐射监测系统研制

基于控制器局域网络(CAN)总线设计了网络化辐射监测系统。监测系统以盖革-米勒计数管(简称G-M管)作为γ射线探测器,采用CAN总线的通信方式实现数据传输的可靠性。整个系统采用模块化设计,可扩展性强,能够实现对γ辐射剂量的在线实时监测。     

基于CAN网络的环境辐射监测系统的研究

该系统以AVR微处理器为核心,利用CAN总线的优势性能,实现了对存在γ辐射场的环境进行远程、实时和可靠的监测。将CAN总线网络应用到辐射监测系统有效地提高了数据传输的可靠性和安全性。文中详细介绍了该系统(CIT-2000A)的基本结构、硬软件设计的方法、上位机数据处理以及实验结果。系统经过长时间的运行,证明技术可靠,性能优良。     

基于CAN总线的辐射监测网与以太网接口设计

介绍了基于CAN总线的辐射监测网与以太网接口设计.系统以LPC2294作为核心处理器,DM9000以太网控制器作为以太网主控芯片构建了Ethemet和多路CAN的网关的硬件电路,将CAN总线探测到的数据通过以太网传输到主控中心进行数据图形汇总显示.     

基于CAN/USB总线的测氡仪多道数据采集系统

岩层塌陷过程壤氡α能谱异常规律研究中,在覆岩采动裂隙动态演变过程的监测监控方面,需要一种可靠、有效、易操作的方法和手段。就此问题提出了基于USB总线和CAN总线的测氡仪多道采集系统,通过CAN总线进行数据传输,实现了多节点通讯,提高了通信质量;同时,使用USB接口实现CAN总线网络与计算机连接和数据采集的解决方案。     

CAN总线在北京正负电子对撞机直线加速器控制系统中的应用

以CAN总线在北京正负电子对撞机(BEPC)直线加速器控制系统中的应用为例,介绍了CAN总线的特点,系统结构以及基于VME总线的CAN接口卡在实验物理和工业控制系统(EPICS)中的软件设计。CAN总线已成功地在北京正负电子对撞机直线加速器控制系统的磁铁电源控制EPICS样机系统中得到应用,取得了满意的结果。     

基于CAN总线的微波干燥装置数据传输系统的研究设计

在微波干燥煤炭的工业环境下,为了保证数据的可靠传输,研究并设计了一种基于CAN总线的数据传输系统。讨论了传输系统的结构、硬件设计、CAN应用层协议、上位机监控等内容,并且重点论述了CAN应用层协议。测试结果表明该数据传输系统稳定性好,可靠性高。     

VME测试系统在嵌入式Linux上的实现

介绍了基于VME总线的测试系统,该测试系统采用PowerPC作为VME机箱的读出插件、嵌入式Linux为操作系统,实现电子学小系统测试的相关功能.首先介绍了系统相关硬件和软件框架及本系统的关键技术和各项功能模块的实现,最后介绍了图形用户界面.该系统可以用于基于VME总线的系统测试以及初步的系统控制.     

核聚变装置辐射监控系统研究

核聚变装置在放电实验期间会产生高能中子和γ射线等辐射,部分辐射会通过生物屏蔽物透射或天空反散射而到达工作场所或者环境。设计并实现了可用于全范围(近、中、远程三种应用条件)中子和光子辐射、计算机集中监控系统(RMS),包括对工作场所进行监测的CAN系统、基于一种新的TRP蓝牙树型拓扑Ad Hoc网络的形成机制和路由协议在装置周围区域内移动状态下进行环境辐射监测的无线网络系统、对远程环境进行监测的移动GPRS无线网络系统。     

CH4气体浓度分布式监控系统研究与设计

针对热催化元件检测方式精度较低、检测范围窄,对高浓度瓦斯气体(CH4)检测会得到致命错误信息的弊端,本系统利用红外瓦斯气体传感实现CH4浓度信号采集,通过运算放大、采样保持、A/D转换后,送入单片机进行处理,并控制现场通风设备等工作,保证煤矿瓦斯浓度值在规定范围以内,以避免事故的发生.另外,系统通过CAN总线将监控装置连接,主控PC机通过RS232及CAN总线通信模块与CAN总线连接实现了工作现场实时监控、数据分析与处理.文章对系统硬件设计及部分软件流程进行了描述.通过实验测试,系统通信良好,浓度检测精度不大于±0.2%,检测线性度好、稳定时间较快,且室温下漂移误差较小.     

BESⅢ超导磁体失超保护及信号采集

介绍了北京正负电子对撞机上北京谱仪(BESⅢ)的超导磁体失超保护系统的设计原理,重点介绍了基于CAN总线的信号采集系统的设计和实现.信号采集系统监测和记录磁体内部关键电压信号以及磁体外部重要的辅助信号,用于分析和诊断磁体的状态,并用LabVIEW完成用户界面程序设计.     

Preparation of Zn/TiO2 powder and its photocatalytic performance for oxidation of P-nitrophenol

Zn-doped TiO2 catalysts were prepared using a sol-gel method and characterized by XPS,UV-Vis, BET, XRD in this study. Under the irradiation of simulant sunlight, the photocatalytic activity for the degradation of p-nitrophenol was studied too. After irradiation for 2.5 h, the degradation percentage of p-nitrophenol could rise to more than 80 %. The results showed that the spectrum absorption band edge of Zn/TiO2 powder does not broaden obviously comparing with pure TiO2 powder. Zinc exists as Zn （11）. When calcined at 973 K, there is a new phase as ZnTiO3 in Zn/TiO2 catalyst. The order of photocatalytic activity of Zn/TiO2 catalysts calcined at different temperatures for p-nitrophenol is 773 K 〉 673 K 〉 873 K 〉 573 K 〉 973 K and the photocatalytic activity of Zn/TiO2 catalyst calcined at 773 K is better than TiO2 catalysts heated at the same temperature, and outclasses that of commercial TiO2 catalyst. It also showed that the photocatalytic degradation of p-nitrophenol follows first-order kinetics under the irradiation of simulant sunlight.     

Current status of radiation therapy for prostate cancer

Radiotherapy for the treatment of prostate cancer has been extensively explored in the past. Along with the comprehensive understanding of the biology of prostate cancer and rapid advances in terms of technology, the out- come of treatment for the patients with prostate cancer has improved. The authors review radiotherapy as the primary treatment for the disease, with particular emphasis on the technological advances from both the radiobiological and radiophysics aspects. Nonconventional fractionated irradiation like hyper- or hypo-fractionation has been imple- mented in the clinic, the final results still need to be confirmed in the future. Technological advances like IMRT, IGRT, in the last two decades have significantly improved the delivery of external radiotherapy to the prostate. This has re- sulted in an overall increase in the total dose that can be safely delivered to the prostate, which has led to modest im- provements in the biochemical outcome. However, establishing the standard therapy for prostate cancer remains con- troversial. It is hoped that the next decades will bring continued advances in the development of biologicals that will further improve current clinical outcomes.     

The control system for SSRF injection and extraction

This paper introduces the injection and extraction control system design for SSRF,which is a distributed control system aimed at stability and reliability of the pulse power supplies,PPS(Personnel Protection System)and MPS(Machine Protection System).The hardware environment is mainly based on PLC(Programmable Logic Con- troller),and ARM(Advanced RISC Machine)is also applied for studying stability of the power supplies.WinCC and EPICS(Experimental Physics and Industrial Control System)have been selected as the platforms of SCADA(Super- visory Control and Data Acquisition).For unifying the interfacing to the control computer,all front-end equipments are connected via Industrial Ethemet.     

水平管内含空气蒸汽强制对流冷凝换热模型研究

为研究含空气蒸汽在水平管内强制对流冷凝换热特性,基于对传热传质过程的分析,建立了管内为环状流与波状流条件下的流动冷凝换热模型。从潜热、显热和液膜3个环节对整个换热过程进行建模,最终得到计算局部冷凝换热系数的理论关系式。模型预测结果与实验数据的对比表明,二者相对偏差在±20%以内,验证了该换热模型的准确性与适用性。通过进一步的研究发现：从换热管入口至出口,随着冷凝的进行,管内换热主要热阻由液膜热阻向气液界面的凝结热阻转变;主流气体对流换热过程基本可忽略。     

Investigations on landmine detection by BF3 detector

Experiments were carried out to investigate the possible use of neutron backscattering for the detection of polyethylene (PE) sample buried in the soil. In detection of landmine by neutrons, the neutron detector and its shield play an important role. In this paper, the effects of graphite, heavy water, polyethylene and boric acid moderators on the flux of back scattered neutrons were investigated. We have also experimentally verified the effect of BF3 detector shield and obtained good agreement with theory.     

Web Services interface of SSRF archive data analysis system

Accelerator database stores various static parameters and real-time data of accelerator. SSRF (Shanghai Synchrotron Radiation Facility) adopts relational database to save the data. We developed a data retrieval system based on XML Web Services for accessing the archive data. It includes a bottom layer interface and an interface applicable for accelerator physics. Client samples exemplifying how to consume the interface are given. The users can browse, retrieve and plot data by the client samples. Also, we give a method to test its stability. The test result and performance are described.     

Assessment of radioactivity levels in some oil samples from the western desert, Egypt

Distributions of natural gamma-emitting radionuclides were determined in 93 oil samples collected from some petroleum fields in the western desert of Egypt. The radioisotope activities in the area under investigation lay in the range of (21 ± 4) to (38 ± 13) Bq?L-1 for 226Ra, (9 ± 2) to (15 ± 5) Bq?L-1 for 232Th, and (154 ± 28) to (303 ± 54) Bq?L-1 for 40K. The mean values were 27, 12, and 201 Bq?L-1, respectively. Among oils, variations in radionuclide ac- tivities could be on account of differences in TDS, HCO3, and Ba, with high or low pH. In this environment, oil prop- erties differently affected the mobilization of natural radionuclides. The range of 226Ra variation had been compared with available data from other countries. The calculated absorbed dose rate ranged from 22.33 to 32.66 nGy?h-1 in lo- cation (B) and (E) respectively, which was less than the accepted value.     

Preparation and properties of 117m Sn(IV)-TTHMP in in-vitro and in small animals

In this work,TTHMP was synthesized and labelled with 117m Sn.The preparation conditions,stability and lipophilicity of 117m Sn(IV)-TTHMP were investigated.Biodistribution of the complex in rabbits and mice was studied.It was found that the quantity of TTHMP and pH value of the prepararion solution had vital effects on the labeling yield of 117m Sn(IV)-TTHMP.It was also found that 117m Sn(IV)-TTHMP was hydrophilic and stable at room temperature and 37℃ in open air 117m Sn(IV)-TTHMP showed unexpectedly high bone uptake and bone-to-blood ratio in the animals.This made it potentially useful as an reagent for skeletal scintigraphy and radiotherapy of bone tumors.     

The role of AGFA high-energy CR in the calibration and quality control of multileaf collimators （MLC）

Linear accelerators equipped with multileaf collimators （MLC） are becoming more common and are widely used in the intensity-modulated radiotherapy （IMRT）. There is an imperative need to ensure the commissioning specification of the linear accelerators for the sake of quality assurance （QA） and quality control （QC）. This paper is aimed to investigate the role of AGFA high-energy CR （Computed Radiography） in calibrating dynamic multileaf collimators and evaluating the accuracy of the leaf position. The result shows that AGFA high-energy CR can easily and conveniently be used to calibrate MLC and verify its position. Hence, the application of AGFA high-energy CR is proved to be an accurate and time-saving method for routine MLC QC, especially when MLC calibration adjustments are required.     

Gamma radiation levels in the ambient environment of the QNPP Base

Monitoring results of gamma dose rate level in 1992～2004 in the ambient environment of the Qinshan Nuclear Power Plants(QNPP)Base,the northeast of Zhejiang Province,are reported in this paper.It is shown that the gamma dose rate of five monitoring sites of 2.5 km to QNPP Base is 84～113 nGy/h,with an average of 96 nGy/h in the 13 years.The average value is close to the background level of 93 nGy/h prior to operation of the QNPP Base,and is lower than the monitoring result of 101 nGy/h at the reference site in Hangzhou City.Within 50 km from the QNPP Base,the cumulative dose rate of the thermoluminescent dosimeter(TLD)is 90 nGy/h,which is lower than the back- ground level of 111 nGy/h.