新型X射线管的研制与性能测试

普遍应用于工业探伤的无损检测设备-X射线探伤机．其核心部分是X射线管。本文设计制作了一种新型结构的X射线管。其阳极采用“大靶”并装有热管，根本上解决散热问题．同时使用无油超高真空排气技术．提高了管内真空度从而改进其性能。使探伤机的连续工作时间与效率提高了一倍。     

基于非介入式X射线管电压测量的研究

为了实现X射线诊断机的质量控制,根据辐射剂量测量的原理,设计了非介入式X射线管电压测量系统.该测量系统以单片机控制系统为平台,智能判断X射线诊断机的照射,通过不同传输路径的射线强度的对比,计算X射线管电压,实现X射线管电压波形的实时存储.实验数据表明,该方法简单有效,安全可靠,适用于X射线诊断机的质量控制,具有广阔的应用前景.     

X射线测厚仪的维护

介绍X射线测厚仪的测量原理、设备构成,着重从生产现场的角度出发,介绍X射线测厚仪的维护要点,并介绍了现场更换X射线管的注意事项。     

关于X光射线管质量特征评定方法的探讨

X光射线管电压,管电流指标是X射线机的重要参数之一.针对传统的管电压,管电流测量方法虽然可以检测出X射线管电压,管电流误差值,但不能反映其质量特征的状况,在分析影响X射线质量高低的因素的基础上,引入了射线管能量带宽的含义,并由此提出了基于Q值及其派生QL值、QH值的射线管电压,管电流分析方法.经过一系列模拟测试和对比分析,结果表明,该方法是传统检测方法的有效补充,能更准确地表征出X射线管电压/管电流质量特征.     

X射线管出射谱源项及过滤谱的蒙特卡罗模拟

利用蒙特卡罗方法对X射线管出射谱及过滤谱进行模拟,研究了X射线管Be窗及靶角对X射线谱的影响,并模拟分析了不同靶角及管电压下X射线管阳极效应.将1 m处经过附加过滤后的模拟谱与德国联邦物理技术研究院(PTB)实测谱进行对比,结果表明,模拟谱与实测谱符合较好,验证了蒙特卡罗方法对模拟X射线管出射谱的有效性及所建模型的正确性.     

医用数字摄影(CR、DR)系统X射线辐射源管电压的测量不确定度评定

医用数字摄影(CR、DR)系统X射线辐射源是疾病诊断的重要设备,X射线管电压是其计量检定中的一个重要项目,本文测量了X射线管电压的示值误差,并评定了其测量结果的不确定度,分析了不确定度来源及评定过程,最后给出测量不确定度报告。     

碳纳米管在X射线管中的应用

迄今碳纳米管的制备技术业已成熟,正逐渐向它的应用进行研究.主要介绍了碳纳米管在X射线管中的应用,给出了两种碳纳米管场致发射X射线管.     

回馈读者 低价售书

JJG744-2004《医用诊断X射线辐射源》检定规程规定,“焦点星卡射线照相法”（如图1所示）检定X射线管焦点时,必须测量X光机焦点到星卡的距离L1及焦点到胶片暗盒的距离L2,这样得到星卡照片上的放大倍率M＇=L2/L1.此种方法对于有标尺和X射线管焦点位置明晰的X光机,测量两点距离简便、适用;对于无标尺及焦点具体位置标注不明确或找不到的X光机,可采用以下两种方法测定M＇.     

残余应力测定的基本知识——第四讲 X射线应力测定方法(三)

5辐射、衍射晶面与应力常数 5.1辐射和滤波片 X射线管发射的X射线分为连续谱线和标识谱线(图19).X射线衍射分析使用标识谱线.当X射线管电压达到并超过靶材的激发电压VK时,来自阴极的高速电子具有了充分的动能,能够撞出靶原子内层(例如K层)电子而产生空穴,原子处于激发状态,外层(例如L和M层)电子向空穴跃迁,以使原子恢复常态;跃迁电子的能级之差以X光量子的形态辐射出来,便是标识谱线.     

医用X射线机射线管真空度降低对检定结果的影响

本文介绍了医用X射线机X射线管真空度降低产生的原因及对检定结果的影响.     

高电压小光斑X射线光管的设计与研制

X射线智能安全检查系统等应用场合,X射线光管的管电压和光斑大小直接影响系统的穿透度与分辨力,管电压越高,穿透力越强,光斑越小,分辨力越高,因此在国家重点研发计划的支持下,设计制造了一种管电压为200 kV、光斑大小为0.4 mm ×0.4 mm的高电压小光斑X射线光管.利用Lorentz电子光学设计软件与热模拟软件对此...     

Measurement of the Parameters of the Focal Spot of an x-Ray Tube Using Kumakhov Optics

A technique of determining the parameters of the focal spot of an x-ray tube by obtaining its image by means of Kumakhov optics is described. Through the use of the image thus obtained, it is possible to determine the size and shape of the effective focal spot. Results of investigations of different x-ray tubes are presented.     

CPT色纯漂移自动测量

提出了凹点法测量显示管色纯漂移,建立了自动测试系统,实现了快速高精度的测试,为高分分辨率彩色显像管（ＨＤＴＶ）的研制提供了有力的工具。     

提高小管径频差法超声波流量计测量精度的数理分析

小管径频差法超声波流量计的测量精度受各种因素的影响，因而获得较高精度比较困难。本文对影响小管径频差法超声波流量计测量精度的多种因素进行数理分析。在此基础上结合多年研制该流量计的实际经验，提出提高测量精度的措施及其方法。     

Secondary radiation in transmission-type X-ray tubes: Simulation, practical issues and solution in the context of X-ray microtomography

In laboratory-based X-ray radiography and computed tomography, the X-rays are assumed to originate from one single focal spot with a finite spot size, which is generated by focussing accelerated electrons on the target material. However, apart from this focal spot, X-rays can also be produced elsewhere in the tube system. A major contribution of this parasitic radiation originates from electrons that are backscattered from the target material, into the X-ray tube system, where they can produce so-called off-focus or secondary X-rays. This phenomenon has been widely studied for rotating anode X-ray tubes in medical imaging systems, but not for transmission-type microfocus X-ray tubes. This paper presents a study on the origin of secondary radiation in this kind of X-ray tubes, which is performed by Monte Carlo simulations and by experimental measurements. The impact of this phenomenon on the imaging process is studied, and two correction methods are proposed, both on the hardware and on the software levels.     

负-正相速跳变慢波结构行波管的小信号理论辅助分析

应用Pierce小信号理论,对设计高效率宽带行波管的一般方法进行分析,采用螺距跳变渐变技术,形成了相速减少和相速增加两段结合的输出段作为宽带行波管的慢波结构,并采用散热性能好的半金属化夹持杆慢波结构产生反常色散曲线。为了提高行波管工作频带的电子效率,在高频点(18 GHz),利用遗传算法并调用1维BWIS互作用程序,对相速减少和相速增加两段相结合输出段的慢波结构进行了优化。计算结果表明:行波管在工作频带(6~18 GHz)获得了比较平坦的饱和输出功率,为下一步实际研制宽带行波管提供了理论依据。     

Process analysis and optimization for failure energy of spot welded titanium alloy

Titanium and its alloys have been applied in many industrial fields because of their high specific strength, good corrosion resistance and high thermal stability. Whereas, there is limited valuable references for recommendations of welding parameter selection and specific standards of the small scale resistance spot welding (SSRSW) of titanium alloy though it has been applied in many industrial production fields. Seventeen tests were designed according to the three-level three-factor Box–Behnken experimental design and the mathematical model correlating the process parameters and the failure energy was established on the basis of response surface methodology (RSM) technique. And then this model was used to analyze the effects/interactions of the welding parameters on the failure energy. The verification test results which were conducted with completely new welding parameters verified that the model presented in this paper was effective and robust. Sensitivity analysis was also carried out to explore the impact of each process parameter on the quality of welding joint. The optimal combination of process parameters for maximum failure energy of the welded joint was obtained using the model based on artificial fish swarm algorithm (AFSA).     

Effects of polarization and phase modulation on the focal spot in 4Pi microscopy

Abstract

In 4Pi microscopy, the intensity and polarization distributions of the focal spot directly determine the system resolution, influencing its extended applications. This paper illustrates how the focal spot is affected by the polarization and phase modulation of the incident beams. Various combinations of polarization states and phase modulations are considered and their effects on the focal spot are investigated. The optimal configurations for generating a solid spot and a doughnut-shaped spot are proposed. This paper provides the theoretical basis and reference for extended applications, such as super-resolution confocal microscopy, 4Pi microscopy or 4Pi-STED microscopy.     

浅谈智慧景区标准化建设

本文从智慧景区的建设现状、旅游景区标准化现状、智慧景区标准化问题,智慧景区标准化实现4个方面进行讨论,并以浙江省服务业标准化试点项目——“江心屿景区智慧旅游标准化试点项目”中的智慧景区标准化建设为例,探讨智慧景区标准化建设内容及智慧景区标准体系框架（智慧部分）的构建。     

汽车制动鼓的失效分析

对两种典型失效形式的汽车制动鼓化学成分、显微组织和硬度等进行了检验和分析。结果表明，制动鼓表面出现的亮白点是成分不合理和制动时摩擦热作用引起相变等导致的，致使制动效果差；而制动鼓表面出现黑斑、龟裂是由于耐热疲劳性能差及发生相变造成的。