Preliminary Tests of a Kerma-Area Product (KAP) Meter to Be Used as a Monitor Chamber in a Conventional Diagnostic X Ray System

This study presents the results of the preliminary tests performed using a kerma-area product (KAP) meter in order to verify its usefulness as a monitor chamber in a clinical X ray system, which will be used in ionization chambers’ quality control program. The tests performed were repeatability, surface measurement uniformity, linearity with tube current, measurement variation changing the distance and field size, KAP chamber radiation attenuation, and energy dependence. The KAP meter has presented a good repeatability (a maximum variation of 0.4%);its surface has a homogeneous response (a maximum variation of 1.0% among the different irradiated regions);the response is linear with the tube current and the variation of the PKA along the distance is less than 3.43%. On the other hand, the results obtained for chamber attenuation and energy dependence show that some corrections must be applied when the measurements are made. The results have shown a good performance of the KAP meter, confirming that it is possible to use this instrument as a monitor chamber. However, it is important to highlight that some correction factors for energy dependence and chamber radiation attenuation must be considered.

Collection efficiency of a monitor parallel plate ionization chamber for pencil beam scanning proton therapy

The collection efficiency of monitor parallel plate ionization chambers is the main uncertainty in the beam control of pencil beam scanning systems.Existing calculation methods for collection efficiency in photon or passive scattering proton systems have not considered the characteristics of non-uniform charge density in pencil beam scanning systems.In this study,Boag’s theory was applied to a proton pencil beam scanning system.The transverse distribution of charge density in the ionization chamber was considered to be a Gaussian function and an analytical solution was derived to calculate collection efficiency in the beam spot area.This calculation method is called the integral method and it was used to investigate the effects of beam parameters on collection efficiency.It was determined that collection efficiency is positively correlated with applied voltage,beam size,and beam energy,but negatively correlated with beam current intensity.Additionally,it was confirmed that collection efficiency is improved when the air filling the monitor parallel plate ionization chamber is replaced with nitrogen.

The Calibration and Use of a New Ring-Shaped Ionization Chamber for Monitoring and Dosimetry of X-Ray Beams

Today, dosimeters are used generally for dosimetry of the diagnostic X-ray beam. Ionization chambers are appropriate instruments for monitoring and also the dosimetry of X-ray beam in medical diagnostic equipment. The present work introduces design and investigation of a new ring-shaped monitor chamber with a PMMA body, graphite-coated PMMA windows (0.5 mm thick), a special graphite-foil central electrode (0.1 mm thick, 0.7 g/cm3 dense) that creating two sensitive volumes and a central hole for crossing the radiation beam with less attenuation. The results of performance tests conducted at the Nuclear Science and Technology Research Institute, AEOI in Karaj- Iran proved the high short and long-term stability, the very low leakage current, the low directional dependence and very high ion collection efficiency through the special design of the collecting electrode. Moreover, the FLUKA Monte Carlo simulations certified the negligible effect of central electrode on this new ring-shaped monitor chamber. According to the results of the performance tests, the new monitor chamber can be used as a standard dosimeter in order to monitor X-ray beam in primary standard dosimetry laboratories.

Development of a novel system for monitoring tritium in gaseous form

Tritium real-time measurement in glovebox or workplace is important to ensure safe operation of tritium. A novel tritium monitor system including an open-walled ionization chamber, an electrometer and an IPC(Industrial Personal Computer) has been developed to measure tritium in gaseous form. Using mesh walls, instead of sealed wall, the open-walled ionization chamber has less tritium absorption and lower memory effect. In addition, tritium gas can diffuse into the chamber's sensitive region without the assistant of sampling system and ion trap, which are installed at the front-end of commonly used flow-through ionization chambers. Background signal of this monitor system is about 3.7 × 105Bq/m3, and after exposed to tritium concentration at about 1011Bq/m3 for 4h, background of the monitor can recover after purging it several times with dry air. It is suitable for longtime tritium measurements in both glovebox and workplace.

Fusion Neutron Flux Monitor for ITER

Neutron flux monitor （NFM） as an important diagnostic sub-system in ITER （international thermonuclear experimental reactor） provides a global neutron source intensity, fusion power and neutron flux in real time. Three types of neutron flux monitor assemblies with different sensitivities and shielding materials have been designed. Through MCNP （Mante-Carlo neutral particle transport code） calculations, this extended system of NFM can detect the neutron flux in a range of 10^4 n/（cm^2.s） to 10^14 n/（cm^2.s）. It is capable of providing accurate neutron yield measurements for all operational modes encountered in the ITER experiments including the in-situ calibration. Combining both the counting mode and Campbelling （MSV; Mean Square Voltage） mode in the signal processing units, the requirement of the dynamic range （107） for these NFMs and time resolution （1 ms） can be met. Based on a uncertainty analysis, the estimated absolute measurement accuracies of the total fusion neutron yield can reach the required 10% level in both the early stage of the DD-phase and the DD-phase, the absolute measurement accuracy full power DT operation mode. In the advanced would be better than 20%.

大型低速风洞结构健康监测系统

为提高风洞调试和运行时的结构安全性,设计研制一种大型低速风洞结构健康监测系统。针对风洞监测对象位置散、可移动的特点,对结构健康监测(structural health monitoring,SHM)需求进行精准分析。在分析基础上,系统采用基于光纤环网和星形连接的混合网络架构,实现对分散结构状态数据的分布式采集、边缘计算和高效传输。运行系统表明:该系统在消声室流致振动监测评估、防护网拦截异物监测诊断等方面发挥了显著作用,有力保障了大型低速风洞运行安全。

选频电磁辐射监测仪器电波暗室比对测量分析

为了提高监测仪器比对结果的可比性,选择场强稳定且不受外界电磁环境影响的场所开展比对是必要的。本文分析总结了在标准电波暗室里开展选频射频电磁辐射监测仪器比对测量的经验和做法,通过比对,暴露出日常工作难以发现的问题,提出监测仪器期间核查相关建议;在稳定的、标准的电磁场环境开展比对,为电磁环境监测仪器比对提供一种新做法。

井下避难硐室系统失效评价与在线监测系统研究

为了实现井下避难硐室的安全管理与灾变应急联动,防止系统功能失效,采用事故树定量分析硐室失效成因与各子系统内在联系,结合工程实践,推导出硐室系统失效经验公式,建立失效评价预警模型。根据井上与井下空间分布特点,提出“双网+双系统”协作架构模式及监测系统的物联网架构;搭建一站式指挥调度专线、双向视频语音等设施,保障了系统在线监测与应急网络安全,扩大了系统协同范围;根据预警模型设计了系统软件的六大功能,完善了系统监测与应急应用,实现了井上、井下信息交互安全畅通。该监测系统已在西南某矿成功应用,有利于降低避难硐室失效事件发生,减少安全检查工作量,提高运维管理效率,提升矿山安全管理智能化水平。

热力小室管道状态远程智慧监测系统的设计与实现

集中供暖系统中直埋敷设方式铺设的管道具有一定的局限性,如不便于检查,管网分布图局限于纸质,巡检人员无法准确地对管网及附属设备进行数字化管理,管网和附属设施的运行状况无法及时获取等。针对以上局限性,设计了一种集中供热管网远程智慧监测系统,能监测管网小室的运行状况(包括温度、水位、补偿器位移量、管网泄漏),及时发现管网小室内的异常情况;DN1400管道收缩膨胀系数会受到钢管温度的影响;预制直埋保温钢管相关参数会随着供热温度的变化而产生一定的变化。系统前端采集设备使用STM32作为主控芯片,配备标准型传感装置进行信息获取,由锂电池供电。系统采用A7680作为终端无线通信装置与系统分析平台进行通信。经过实际测试,系统可以准确获取小室环境温度、管壁温度、水位、补偿器位移量、泄漏相关参数。

基于DBSCAN与BP神经网络的轮速传感器故障诊断研究

针对工业生产时轮速传感器性能测试数据过多,难以对其故障类型进行识别的问题,设计了基于DBSCAN与BP神经网络的轮速传感器故障诊断方法。首先,根据轮速传感器工作原理以及实际测试数据分析了轮数传感器故障类型以及对应的故障数据。然后,利用DBSCAN对轮速传感器的性能测试数据进行异常值检测,同时建立BP神经网络进行训练及测试,用于对异常值对应的故障类型进行诊断与分类,并将BP神经网络与GRNN神经网络以及PNN神经网络的故障诊断速度以及准确率进行对比。实验结果显示:针对轮速传感器故障类型检测BP神经网络的速度及准确率有明显优势,该文设计的轮速传感器故障检测算法能够准确的从测试数据中提取故障数据并进行故障诊断。

引江济淮东淝河船闸施工技术

针对引江济淮东淝河船闸四面临水、建设条件复杂、船闸闸室墙一次成型等问题,进行水文与地质情况分析,并进行降水井的试验井对比试验,确定了深基坑降水方案与监测方法。结合已有船闸闸室墙钢筋安装和人字门安装方法,分析其存在的问题,提出船闸闸室墙钢筋整体预制与安装、人字门精细制作与精确定位等施工技术。研究成果保证东淝河复线船闸得以顺利建成,提升了船闸建设安全与质量,闸室墙钢筋预制安装工艺在船闸闸室墙工程的应用进一步丰富和提升了改扩建船闸施工的方法和品质。

基于嵌入式的药品稳定性试验箱远程监控系统设计

药品稳定性试验箱在药品领域中的关键作用日益凸显,然而传统的设备管理方式存在效率低、维护成本高等问题。为解决这一问题,设计了一种基于嵌入式的药品稳定性试验箱远程监控系统。该系统可实时监控试验箱的温度、湿度、加热器和制冷器等运行状态信息,巡视人员通过App可远程实时监控,有效提高管理效率,降低维护成本。

家用吸氧雾化诊疗监控语音微压氧舱

现有家用微压氧舱功能单一,只能吸氧,体验感差,无视频监控语音通话、体征监测、大数据统计、养生雾化等功能。针对这些问题,提出了吸氧雾化诊疗监控语音一体家用氧舱,其既可以吸氧,又可以加入雾化液,还配备了按摩椅和医疗级别的智能体征监测手环,记录吸氧过程和人体健康状况,以进行横向和纵向对比,生成每日健康表。使用大数据与同龄其他人进行比较,配备了高清平板电脑,并具有语音识别功能,用户可通过带唤醒词的语音控制氧舱基本操作。其安装了可以视频通话功能的摄像头,其可远程查看与通话,极大地提高了用户体验感,功能更丰富。

辐射环境空气自动监测站故障及处理的研究

随着核电事业的快速发展和核技术应用的不断扩大,辐射环境安全问题日益受到社会关注。辐射环境空气自动监测站作为监测环境辐射水平的重要设施,在保障公众健康、维护社会稳定方面发挥着不可替代的作用。然而,由于自动监测站长期在野外运行,设备老化、供电系统不稳定、网络通信故障等问题频发,严重影响了监测数据的准确性和时效性。因此,开展辐射环境空气自动监测站故障与处理的研究,对提高监测站运行效率、保障监测数据质量具有重要意义。

TAM-Ⅱ型空气中氚监测仪的研制

介绍了 TAM- 型实时连续氚监测仪的研制。仪器的探测器由 4个对称放置的有效体积为2 L丝壁电离室构成 ,使电离室对被监测氚产生的记忆效应减到最小 ,对 γ本底的补偿 ,在几乎所有方向好于 97%。该探测器配备一台工作在微电流积分模式的场效应管静电计 ,氚监测仪的测量过程由一个单片机自动控制 ,如自动转换量程、数据显示、储存与处理。该监测仪的测量范围为 6～ 10 6Bq/L,特别适用于氚设施和实验室手套箱或烟囱排出氚的连续自动监测。

ITER中子通量监测器原型的研制

研制的用于国际热核实验堆(ITER)的中子通量监测器由裂变室探测器组合构成,包括两只不同灵敏度的阴极上涂有高纯裂变材料235U的裂变室探测器和一只未涂裂变材料的'空白'探测器。此组合用于中子、γ射线、硬X射线的混合辐射场条件下对中子的测量,可完全扣除后两种辐射对中子通量测量的影响,提高测量精确度。探测器的电压坪长、坪宽、坪斜、计数坪特曲线及宽度、输出脉冲宽度和探测系统计数率等主要参数经测试已达到设计要求,部分参数(如计数率)已接近ITER近期的技术水平。通过提高相关材料的纯度、优化裂变室结构和采用Campbelling模式及高精度的信号选择器,可研制出适用于ITERD D聚变条件下(低聚变中子产额)的快中子通量监测器。

大气中PAN的测定及其与前体物的关系

对北京中关村地区大气中PAN的监测结果表明:在强日照条件下,PAN浓度随汽车等排放和NO_2浓度的增加而增加,高PAN浓度水平与高O_3浓度相关联;夏季的PAN浓度明显高于春季.模拟实验的结果证实:C_3H_6是大气中重要的PAN前体物,在一定范围内,其浓度越高,PAN浓度越大;C_2H_4生成PAN是困难的,H_2O_2的存在对C_2H_4反应生成PAN有促进作用;大气中SO_2的存在可降低PAN的生成速率.在<400nm光照条件下,PAN光解迅速;而其热解则需较高温度,在室温下其热解的半衰期达17.3b,这对说明大气中PAN的长距离传输和深夜PAN的存在是重要的.

高压氧舱自动监控系统的设计与开发

在高压氧舱自动监控系统设计中采用基于PC总线的工控机,利用PCL系列控制板对舱室进行控制,并利用Lab Windows／CVI虚拟仪器编程语言实现了监控系统的软件编程。采取了模糊-神经元控制策略,提高了系统的可靠性。

基于AT89C52的恒温室监控系统设计

阐述了AT89C52单片机的工作原理,对当前采用的恒温加热方式进行对比和分析,从生物制品和药品所用恒温室的功能和材料两方面,分析说明了恒温室的设计思路和控制方法;给出了恒温系统的设计电路和恒温控制方法。在系统控制算法中,采用分段拟合PID控制算法,实现了恒温室的恒温控制;最后,用具体实例进行了论证。

数字式温湿度传感器在氡室监测系统中的应用

阐述了在氡室监测系统中使用的基于CMOSens 技术的SHT75数字式温湿度传感器的主要特点、内部结构、测量标度转换方法和监测系统中温湿度数据采集的整体实现。基于SHT75数字式温湿度传感器的氡室温湿度监测系统具有电路结构简单、实时性强、精度高、稳定性好、直观等特点。