一种提高光电探测系统测量上限的方法

在分析各种调节光电探测器灵敏度常用方法的基础上,提出一种提高光电探测器测量上限的方法,其基本要点是通过使用狭缝准直器来限制进入光电探测器的辐射强度;通过使辐射侧照闪烁体,有效屏蔽或避开强辐射源对光电探测器光阴极的直接辐射干扰;通过拉开闪烁体至光阴极的距离,利用空气柱进一步衰减进入光电探测器光阴极的荧光光子数,按这种方法设计的光电探测系统,在相同的信噪比情况下可以测量更高的核辐射注量,本文提供了设计实物照片和实验测量数据.     

基于FPGA和ARM的中子能谱测量系统设计

针对多球中子谱仪不便于携带、测量时间长、操作过程复杂等问题,设计了基于FPGA和ARM的单球中子谱仪。将⁶Li玻璃闪烁体和硅光电倍增管(SiPM)耦合制成热中子探测器,采用互阻放大电路对信号进行转换,经过放大、整形、采集和处理,得到各探测器计数值,用于计算中子能谱。实验结果表明：探测单元设计合理,能够有效实现中子信号向电压信号的转换,输出信号脉冲幅度为-2.80 V,脉冲宽度为325 ns;电子学系统软硬件稳定可靠,采集计数的漏计数率低于1%。     

基于雪崩光电二极管阵列的化学发光测量系统设计

以开发便携式化学发光免疫分析仪为应用目标,进行了基于雪崩击穿光电二极管阵列（SiPM）化学发光测量系统软硬件平台的设计。系统采用ARM9为主处理器,负责数据分析、无线通信与人机交互界面功能的实现;采用FPGA控制高速A/D转换器进行信号采集和数据缓存;具体进行了各功能模块之间的接口设计。     

光纤阵列准直器设计及其发散角测量

传统基于单个固定折射率透镜和渐变式折射率透镜制备光纤阵列准直器的方法,存在阵元数扩展困难、封装工艺复杂且集成化困难等缺点。利用光学微透镜易阵列化且阵元特性一致性好等优点,提出了基于平凸微透镜阵列制备光纤阵列准直器的方法。根据高斯光学和矩阵光学理论,对光纤阵列准直器的准直特性进行了理论分析和仿真,确定了光纤阵列准直器的相关设计参数,据此加工制备了四阵元一维排布光纤阵列准直器,其阵元间距为250 μm。通过远场光斑法对光纤阵列准直器的主要性能参数远场发散角进行了测量,并采用蒙特卡洛法对测量不确定度进行了分析与评定。光纤阵列准直器各通道远场发散角的测量值分别为0.69°,0.67°,0.71°,0.68°,测量扩展不确定度为0.02°,该测量结果在设计容差(0.68±0.03)°之内。该光纤阵列准直器具有良好的准直特性,能够满足光纤通信系统中光纤阵列准直器小型化和集成化的需求。     

基于SiPM的线阵式X射线背散射探测器设计与性能评估

为了实现现场快速安全检查过程中敏感物质的细分,探讨了一种通过X射线背散射信号求取物质密度的方法,并完成了实现该方法的核心部件——一种基于硅光电倍增管（SiPM）的的线阵式闪烁体探测器的设计和功能验证。该探测器具有能量分辨的能力,能够分析不同物质在不同能量下的散射衰减。在环境温度-10℃～50℃条件下,该探测器输出的脉冲幅值稳定,能量分辨率在221%～257%变化（室温条件时能量分辨率为236%@595 KeV）。其线阵的结构为实现散射与透视图像空间上的一一对应,进而实现散射信息与透视信息的融合打下了基础。不同材料的散射能谱测量结果表明,该探测器所探测的能量曲线能够反映物质的密度特性,验证了其用于散射能谱探测以实现物质分类的可行性,在现场查缉装备的智能识别方面极具应用前景。     

气动高压激励的阵列式盘型压电俘能器

提出了利用气动高压激励的阵列式盘型压电俘能器实现气体能量的转化,以满足低功耗传感器的自供能需求。通过压电单晶片将气缸内部高压气体能量转化为电能,设计了阵列式盘型压电俘能器的样机结构;结合气缸的正常工作状态,分析了压电阵列的工作原理并进行了相应的实验。理论分析显示:盘型压电阵列具有较高的电荷量与良好的电容性,适合对具有交变载荷的高压气体能量进行收集。采用外径为12 mm、厚度为0.2 mm的压电单晶片及缸径为63mm、行程为150mm的气缸制作了实验样机,利用气动组件模拟气体环境搭建了测试系统。分别调节压力、周期、流量等参数进行了实验测试。结果表明:在交变的气动高压激励下,阵列式盘型压电俘能器可较好地收集交变高压气体载荷能量,其最佳匹配电阻为600kΩ,最大的瞬时功率为1 052μW,输出功率可满足低功耗传感器的能量需求。     

新型组合式离子探测器

本离子探测器是由连续电子倍增管和闪烁探测器两部分组成的。国产BDT型陶瓷连续电子倍增管用作离子—电子转换和次级电子放大。闪烁晶体及光电倍增管等组成的闪烁探测器用来探测电子倍增管输出的电子束流。这种组合式离子探测器具有低噪声(10~(-21)安培)和优良的脉冲幅度分辨率等优点。在15千伏转换电压下可获得幅度为6伏的脉冲信号,探测灵敏度为10~(-19)安培。     

小型准直式红外地球模拟器研究

地球模拟器是卫星姿态测量控制关键部件—摆动扫描式红外地球敏感器的一种重要地面模拟试验与精度标定仪器。本文针对卫星同步轨道高度(35786km),采用准直式方案,研制了一种口径为Φ150mm的准直式红外地球模拟器,它能提供17.46°的地球张角,实现了地面上模拟卫星在太空中所看到的地球。文中详细介绍了准直式红外地球模拟器的组成和总体结构,采用红外光学技术,设计了锗准直透镜,通过理论分析得出地球光阑、热地球位置和大小与地球张角、锗准直透镜光学参数之间的关系,为地球模拟器的研制提供了设计依据。地球张角是衡量地球模拟器精度的指标,通过实验对地球张角进行了测试,结果表明地球张角误差小于±0.05°。     

SiPM阵列电子特性建模和三维测深仪前端电子学优化

从硅光电倍增管(SiPM)单个微元的微等离子体电子行为模型出发,分析了SiPM的电子特性,提出了SiPM前端电子学最优设计方案。阐述了SiPM的工作机理,给出了SiPM的电子行为模型,分析了SiPM应用于水下三维测深的优势。根据水下测深信号的回波特性,设计了高速、高带宽的前置放大器,并对前置放大器进行了交流分析和瞬态分析。结果表明,该前置放大电路在带宽内具有很高的增益平坦度,相位裕度大于60°,基本保证了信号的完整性,同时保持了激光脉冲的波形。分析和测试结果表明,该探测器和电路设计方案完全能够满足水下三维测深的需要。     

闪烁探测器—计算机测量系统

本文报道配置在МИ1301型质谱计上的闪烁探测器—计算机测量系统。闪烁探测器包括由离子入口缝、法拉第筒、离子—电子转换电极、闪烁晶体、光导管和光电倍增管组成的转换电极室;由振簧静电计、记录仪组成的直流测量装置;由脉冲放大器、多道分析器、磁场—多道扫描器、打印机、扫谱仪组成的脉冲计数测量装置。计算机采用匈牙利EMG666微机,自行设计多道分析器—计算机接口。对本测量系统的转换效率、脉冲幅度分布以及转换电压等多种条件与探测器性能的关系进行了系统的测定。用本系统测定的铷同位素丰度比为2.596±0.003,无质量歧视效应。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.