Design and prototyping of the readout electronics for the transition radiation detector in the high energy cosmic radiation detection facility

The high energy cosmic-radiation detection(HERD)facility is planned to launch in 2027 and scheduled to be installed on the China Space Station.It serves as a dark matter particle detector,a cosmic ray instrument,and an observatory for high-energy gamma rays.A transition radiation detector placed on one of its lateral sides serves dual purpose,(ⅰ)calibrating HERD's electromagnetic calorimeter in the TeV energy range,and(ⅱ)serving as an independent detector for high-energy gamma rays.In this paper,the prototype readout electronics design of the transition radiation detector is demonstrated,which aims to accurately measure the charge of the anodes using the SAMPA application specific integrated circuit chip.The electronic performance of the prototype system is evaluated in terms of noise,linearity,and resolution.Through the presented design,each electronic channel can achieve a dynamic range of 0–100 fC,the RMS noise level not exceeding 0.15 fC,and the integral nonlinearity was<0.2%.To further verify the readout electronic performance,a joint test with the detector was carried out,and the results show that the prototype system can satisfy the requirements of the detector's scientific goals.

FPGA-based position reconstruction method for neutron beam flux spatial distribution measurement in BNCT

A new measurement method for the spatial distribution of neutron beam flux in boron neutron capture therapy(BNCT)is being developed based on the two-dimensional Micromegas detector.To address the issue of long processing times in traditional offline position reconstruction methods,this paper proposes a field programmable gate array based online position reconstruction method utilizing the micro-time projection chamber principle.This method encapsulates key technical aspects:a self-adaptive serial link technique built upon the dynamical adjustment of the delay chain length,fast sorting,a coordinate-matching technique based on the mapping between signal timestamps and random access memory(RAM)addresses,and a precise start point-merging technique utilizing a circular combined RAM.The performance test of the selfadaptive serial link shows that the bit error rate of the link is better than 10-12 at a confidence level of 99%,ensuring reliable data transmission.The experiment utilizing the readout electronics and Micromegas detector shows a spatial resolution of approximately 1.4 mm,surpassing the current method’s resolution level of 5 mm.The beam experiment confirms that the readout electronics system can obtain the flux spatial distribution of neutron beams online,thus validating the feasibility of the position reconstruction method.The online position reconstruction method avoids traditional methods,such as bubble sorting and traversal searching,simplifies the design of the logic firmware,and reduces the time complexity from O(n2)to O(n).This study contributes to the advancement in measuring neutron beam flux for BNCT.

Online Magnetic Flux Leakage Detection System for Sucker Rod Defects Based on LabVIEW Programming

Aiming at the detection of the sucker rod defects,a real-time detection system is designed using the non-destructive testing technology of magnetic flux leakage(MFL).An MFL measurement system consists of many parts,and this study focuses on the signal acquisition and processing system.First of all,this paper introduces the hardware part of the acquisition system in detail,including the selection of the Hall-effect sensor,the design of the signal conditioning circuit,and the working process of the single chip computer(SCM)control serial port.Based on LabVIEW,a graphical programming software,the software part of the acquisition system is written,including serial port parameter configuration,detection signal recognition,original signal filtering,real-time display,data storage and playback.Finally,an experimental platform for the MFL detection is set up,and the MFL measurement is carried out on the transverse and longitudinal defects of the sucker rod surface.The experimental result shows that the designed acquisition and processing system has good detection performance,simple design and high flexibility.

Composite excitation multi-extension direction defect magnetic flux leakage detection technology

In the traditional pipeline magnetic flux leakage(MFL)detection technology,circumferential or axial excitation is mainly used to excite the magnetic field of defects.However,the domestic and foreign pipeline detection devices currently in operation are mainly axial excitation MFL detection tools,in which circumferential cracks can be clearly identified,but the detection sensitivity of axial cracks is not high,thus forming a detection blind zone.Therefore,a composite excitation multi-extension direction defect MFL detection method is proposed,which can realize the simultaneous detection of axial and circumferential defects.On the basis of the electromagnetic theory Maxwell equation and Biot Savart law,a mathematical model of circumferential and axial magnetization is firstly established.Then finite element simulation software is used to establish a model of a new type of magnetic flux leakage detection device,and a simulation analysis of crack detection in multiple extension directions is carried out.Finally,under the conditions of the relationship model between the change rate of leakage magnetic field and external excitation intensity under unsaturated magnetization and the multi-stage coil magnetization model,the sample vehicle towing experiment is carried out.The paper aims to analyze the feasibility and effectiveness of the new magnetic flux leakage detection device for detecting defects in different extension directions.Based on the final experimental results,the new composite excitation multi extension direction leakage magnetic field detector has a good detection effect for defects in the axial and circumferential extension directions.

Initial Rotor Position Detection of 12/10 Flux-switching Permanent Magnet Motors

电机转子初始位置检测的精度直接决定其启动运行时的性能。针对12/10极永磁磁通切换型电机,在验证其凸极性的基础上,采用注入脉振高频信号实现转子初始位置估计。通过对传统高频脉振正弦电压信号注入的分析,研究了基于高频方波或三角波的注入方法,再利用电流差值调制或直接信号调制方法得到位置误差信号,同时根据磁路的饱和效应,通过对d轴电流过零点时间差值的累加,实现了磁极方向辨识。分析了位置误差信号的系数与初始位置检测收敛性的关系。通过实验验证了所提方法的正确性和可行性。

Readout electronics for a high-resolution soft X-ray spectrometer based on silicon drift detector

The readout electronics for a prototype soft X-ray spectrometer based on silicon drift detector(SDD),for precisely measuring the energy and arrival time of X-ray photons is presented in this paper.The system mainly consists of two parts,i.e.,an analog electronics section(including a pre-amplifier,a signal shaper and filter,a constant fraction timing circuit,and a peak hold circuit)and a digital electronics section(including an ADC and a TDC).Test results with X-ray sources show that an energy dynamic range of 1-10 keV with an integral nonlinearity of less than 0.1%can be achieved,and the energy resolution is better than 160 eV @ 5.9 keV FWHM.Using a waveform generator,test results also indicate that time resolution of the electronics system is about 3.7 ns,which is much less than the transit time spread of SDD(<100 ns)and satisfies the requirements of future applications.

Key technique of a detection sensor for coal mine wire ropes

Wire ropes,employed extensively in coal mine hoists and transportation systems are subject to damage due to wear,corrosion and fatigue.The extent of damage and the carrying capacity of ropes are closely related to the sense of safety by staff and equipments.Magnetic flux leakage detection method(MFL),as an effective method,is these days widely used in detection of broken strands of wire ropes.In order to improve the accuracy of detection of flaws in wire ropes by magnetic flux leakage(MFL),the effect of the distance between a sensor and the surface of a wire rope(i.e.,lift-off) on detection by magnetic flux leakage was in-vestigated.An analysis of the main principles for the choice of lift-off is described by us and a new method that improves the structure of the detector is proposed from the point of view of the design of a magnetic circuit,to restrain the impact of fluctuations of sensor lift-off.The effect of this kind of method is validated by simulation and computation.The results show that the detection sensitivity is markedly increased by this method.Furthermore,the signal-to-noise ratio(SNR) can be increased by over 28%.This method will lend itself to offer reliable scientific information to optimize the structure of excitation devices and improve the accuracy of MFL detection.

Detecting the Position of the Moving-iron Solenoid by Non-displacement Sensor Based on Parameter Identification of Flux Linkage Characteristics

Currently, most researches use signals, such as the coil current or voltage of solenoid, to identify parameters; typically, parameter identification method based on variation rate of coil current is applied for position estimation. The problem exists in these researches that the detected signals are prone to interference and difficult to obtain. This paper proposes a new method for detecting the core position by using flux characteristic quantity, which adds a new group of secondary winding to the coil of the ordinary switching electromagnet. On the basis of electromagnetic coupling theory analysis and simulation research of the magnetic field regarding the primary and secondary winding coils, and in accordance with the fact that under PWM control mode varying core position and operating current of windings produce different characteristic of flux increment of the secondary winding. The flux increment of the electromagnet winding can be obtained by conducting time domain integration for the induced voltage signal of the extracted secondary winding, and the core position from the two-dimensional fitting curve of the operating winding current and flux-linkage characteristic quantity of solenoid are calculated. The detecting and testing system of solenoid core position is developed based on the theoretical research. The testing results show that the flux characteristic quantity of switching electromagnet magnetic circuit is able to effectively show the core position and thus to accomplish the non-displacement transducer detection of the said core position of the switching electromagnet. This paper proposes a new method for detecting the core position by using flux characteristic quantity, which provides a new theory and method for switch solenoid to control the proportional valve.

Real-Time Traffic State and Boundary Flux Estimation with Distributed Speed Detecting Networks

The rapid development of 5G mobile communication and portable traffic detection technologies enhances highway transportation systems in detail and at a vehicle level. Besides the advantage of no disturbance to the regular traffic operation, these ubiquitous sensing technologies have the potential for unprecedented data collection at any temporal and spatial position. While as a typical distributed parameter system, the freeway traffic dynamics are determined by the current system states and the boundary traffic demand-supply. Using the three-step extended Kalman filtering, this paper simultaneously estimates the real-time traffic state and the boundary flux of freeway traffic with the distributed speed detector networks organized at any location of interest. In order to assess the effectiveness of the proposed approach, a freeway segment from Interstate 80 East (I-80E) in Alameda, Emeryville, and Northern California is selected. Experimental results show that the proposed method has the potential of using only speed detecting data to monitor the state of urban freeway transportation systems without access to the traditional measurement data, such as the boundary flows.

长输油气管道内检测技术

管道内检测技术是长输油气管道内检测最有效的方法之一,是长输油气管道缺陷检测、评估与完整性评价的重要手段。随着我国能源行业的高速发展,管道成为能源输送的最有效载体,这对管道内检测技术提出了新的挑战,应运而生多种新的检测方法与解决方案。梳理了长输油气管道内检测技术的发展过程,阐述了长输油气管道内检测技术的国内外研究现状,针对长输油气管道内检测现存在的问题,对新技术、新方法的原理、应用情况进行归纳总结,并提出管道内检测行业的未来展望。

基于主动识别声呐的养殖塘南美白对虾探测与初步分析

为实现高效、快速和准确的虾类识别和行为观测,提出一种基于主动识别声呐(DIDSON)的养殖塘南美白对虾探测和行为分析方法。该方法利用无人艇搭载主动识别声呐(DIDSON)对养殖塘设置的8个观测点进行连续定点观测,利用基于ECHOVIEW构建的虾类识别计数模型对采集的图像数据进行识别提取,通过目标识别、目标提取、通量分析以及方向分析等方法获得养殖塘南美白对虾的初步行为特征。试验在8个观测点观测的虾群数量极值分别为251只和208只,均值为234只,单位时间内的虾群通量区间为[108,131]只/(min·m^(2)),不同点位虾群正向游塘的占比均大于85%,通量变化较小。结果显示,该方法可以观测到养殖塘内虾群存在规律性的游塘行为,相较于传统的水下视觉观察和被动声呐调查,有效解决了养殖塘中虾群行为观测的难题,为制定更加高效的虾塘饲养和管理方案提供科学的数据支持。

一种基于单轴向充磁永磁环励磁的钢丝绳无损检测方法

为提高钢丝绳缺陷检测能力,简化励磁结构,提出一种基于单个轴向充磁永磁环励磁的钢丝绳无损检测方法。通过分析钢丝绳缺陷在单个轴向充磁永磁环励磁方法下产生的漏磁场,得到该方法能通过漏磁场感知缺陷运动方向的结论。在此基础上,利用COMSOL软件对该励磁方式进行有限元建模,通过仿真计算缺陷处漏磁的分布,验证了结论的正确性,分析了影响漏磁场的因素,并结合霍尔元件性能参数,给出了传感器的最佳布置位置。最后,通过设计信号调理电路,结合3D打印实现传感器结构,完成了实验平台搭建。仿真结果表明,对于同一缺陷,基于该励磁方式产生的最大漏磁场明显大于传统方式。实验结果表明,对于10 mm粗的钢丝绳,当霍尔元件布置的提离值为3 mm和8 mm时,均能够通过缺陷处漏磁信号感知钢丝绳运动方向。

拱顶储罐罐顶缺陷漏磁检测技术研究

针对拱顶储罐在长期使用过程中,罐顶因环境因素和储存介质的影响造成内外壁腐蚀损伤而严重威胁储罐安全运行的问题,对拱顶储罐罐顶进行了缺陷漏磁检测技术研究。建立了罐顶漏磁检测三维模型,并采用有限元分析方法对该模型进行求解;分析不同影响因素对漏磁信号特征的影响,通过对漏磁场峰值的拟合,得到了不同影响因素对罐顶缺陷漏磁场的影响规律。结果表明,外壁半球形缺陷漏磁检测信号峰值与缺陷半径符合线性拟合规律,内壁半球形缺陷漏磁检测信号峰值与缺陷半径符合二次拟合规律,加强肋处形成的漏磁检测信号与缺陷检测信号波形相反。通过试验验证了漏磁检测方法能有效检测储罐罐顶的缺陷,并能确定缺陷的深度和位置。

飞轮储能用磁轴承综述

磁轴承是利用磁场力将转子悬浮于空间,实现定子与转子之间无机械接触的一种新型支承轴承,在飞轮储能领域具有非常广阔的应用前景。阐述了飞轮储能工作原理以及常见的4种磁轴承支承方式,根据偏置磁通产生方式、受控自由度数量、磁极数量对磁轴承结构进行分类介绍,并对磁轴承关键技术参数优化、无传感控制技术以及解耦控制技术进行综述,指出磁轴承关键技术的未来发展趋势是使用智能算法建立模型求最优解。

Domain-flux僵尸网络域名检测

针对现有Domain-flux僵尸网络检测方法在检测范围方面的不足,提出基于域名访问活跃特征的Domain-flux僵尸网络域名检测方法。通过阐述Domain-flux僵尸网络所利用的域名集合在访问方面所表现出的时间行为特征,提出一种基于域名访问活跃特征的检测算法,给出检测算法的具体描述、检测处理流程及系统整体结构,利用某运行商DNS服务器镜像数据实验验证检测算法。实验结果显示,检测算法不依赖于具体的域名字符特征,可以有效过滤出Domain-flux僵尸网络所利用的域名。

基于IP分布及请求响应时间的恶意fast-flux域名检测算法

提出了一种基于域名对应IP分布及IP对请求响应时间波动的恶意fast-flux域名检测算法。该算法基于合法域名与fast-flux僵尸网络域名在域名解析IP的分布特性与IP对请求响应时间波动特性方面的差异,将解析IP分布特性与IP对请求响应时间的波动性作为参量生成两维特征,给出具体的特征表示。通过SVM分类器进行实验验证了该两维特征的分类效果。特征分析及实验结果表明,相比于现有的检测方法,文章算法能够更准确地检测恶意fastflux域名,虚警率、漏报率较低。

改进Canny算子的小管径弯头漏磁缺陷图像量化方法

弯头作为管道的重要组成部件,受流体冲刷侵蚀等形成的缺陷对其安全运行构成威胁。漏磁检测是管道缺陷检测的有效技术,缺陷的精确量化具有重要意义。为了研究小管径弯头不同位置缺陷图像规律,并提高缺陷量化精度,提出一种改进Canny算子的小管径弯头漏磁缺陷图像量化方法。通过建立小管径弯头漏磁内检测仿真模型,分析了弯头不同位置处金属损失缺陷的图像规律。采用形态滤波和OTSU优化Canny算子,结合图像处理方法构建了缺陷图像量化模型,并对弯头不同位置缺陷深度量化做修正处理。实验结果表明,弯头不同位置缺陷在图像上呈现出明显的差异性,量化模型对缺陷长度和宽度的量化具有较高的精度,误差均小于2 mm。缺陷深度的量化误差较大,修正后深度量化的精度为86.34%,满足金属损失缺陷量化精度需求。该方法可实现缺陷漏磁图像量化处理,对管道漏磁缺陷量化具有一定意义。

掺氢天然气管道氢损伤管外漏磁检测机构设计

掺氢天然气管道受氢损伤等因素影响,容易产生缺陷进而导致管道失效,因此需要定期对掺氢管道进行检查。通过对掺氢管道的主要缺陷产生机制和缺陷特征进行分析,得到主要的缺陷形式,设计一种针对掺氢管道氢损伤的管外漏磁检测机构对管道进行缺陷检测,利用Maxwell进行漏磁检测仿真模拟,采用响应面法建立检测探头各参数与轴向漏磁曲线峰谷差值、吸附力和成本之间的函数,得到探头的结构参数最优组合。最后搭建实验台,利用单组探头进行单通道的漏磁检测。结果表明:与未优化结构对比,优化后管外缺陷检测效果提高26.2%,管内缺陷检测效果提升11%,探头与管壁吸附力降低56.7%,探头成本降低14%,检测效果得到提升;优化探头不仅能检测到已成型的比较明显的掺氢管道缺陷,也可以在缺陷形成早期管壁损失达到整体壁厚40%时将其检测出来。缺陷检测实验验证了文中设计方案的可行性。

基于多模态特征融合的Fast-Flux恶意域名检测方法

Fast-Flux恶意域名是僵尸网络通信中的一种重要载体,通过快速变换域名解析的IP抵御检测。目前,恶意域名检测系统大多基于传统机器学习模型,需要对数据进行复杂处理和特征提取,并且需要借助大量第三方数据源,导致检测的实时性较差。域名解析是一个复杂的过程,并且具有丰富的特征,文章设计了基于多模态特征融合的Fast-Flux恶意域名检测方法。首先利用GCN模块提取空间特征,采用BiLSTM模块提取域名文本特征,然后利用MLP模块提取侧信息特征,最后利用神经网络将这3种特征进行融合。在Fast-Flux-Attack-Datasets公开数据集上进行实验,实验结果表明,该方法的精确率达99.94%、召回率达99.76%、准确率达99.69%,总体效果优于当前同类方法。文章所提方法有效融合了域名解析的多模态特征,明显提升了检测效果,对于提高僵尸网络检测能力具有重要意义。

原油储罐泄漏检测技术研究

原油储罐在复杂的内外部环境中最容易出现的失效形式是底板穿孔从而导致原油泄漏。文章介绍了声发射方法和漏磁扫描方法应用于储罐底板的泄漏检测。两种方法都可以评估与定位底部材料的损伤及底板材料的微泄漏。文章介绍了原油储罐泄漏检测原理,分析了现场检测过程,对同一具原油储罐进行声发射和漏磁扫描检测后,对两种方法的检测结果进行分析与经济性对比,进而给出该储罐的完整性评估,并提出储罐的检修意见。