太赫兹光谱和成像技术在毒品识别和检测方面的应用

介绍了太赫兹时域光谱和成像技术在毒品识别和检测中的应用研究结果;主要报道了利用太赫兹时域光谱技术对隐藏在信封中的毒品的识别,并对粉末状毒品与片状毒品的太赫兹吸收光谱进行了比较;在理论模拟方面,利用密度泛函理论对毒品振动光谱进行了计算;同时应用太赫兹成像技术对毒品进行了识别.研究结果充分表明太赫兹电磁波在毒品检测和缉毒工作中的有效性.     

虚拟仪器在太赫兹光谱系统中的应用

本文概述了太赫兹技术及其研究领域,并详细介绍了虚拟仪器在太赫兹光谱研究中的应用。基于虚拟仪器技术,我们实现了太赫兹时域光谱系统的自动化测量,并在同一软件系统中集成了太赫兹光谱数据的分析系统,为太赫兹光谱实验平台奠定了基础。     

几种加氢裂化催化剂的太赫兹光谱研究

采用太赫兹时域光谱(THz-TDS)方法,本文研究了几种Y型加氢裂化催化剂(NaY、ReY、USY和HY)在0.2-1.2THz频段的光谱特性.与此同时,对其中的NaY分子筛进行了加热处理,测量了其经过不同温度处理后的太赫兹时域光谱.通过快速傅里叶变换,分别得到了不同种类和不同温度处理后催化剂的太赫兹吸收谱和折射率谱.研究结果表明,太赫兹时域光谱技术既能用于催化剂的种类鉴别和性能表征,又能给出不同温度下催化剂本身内部结构变化对应的太赫兹光谱响应.本研究工作的展开,证明了太赫兹方法用于催化剂性质表征的可行性,对太赫兹技术在催化领域的应用具有一定的指导意义.     

掺硫硒化镓晶体在太赫兹波段的光学特性

利用太赫兹时域光谱技术测量了掺硫硒化镓(GaSe1-xSx)晶体在太赫兹波段的光学参数,包括折射系数、吸收系数等.使用自由空间电光取样法获得了太赫兹电磁波的脉冲波形.对不同硫掺杂量的硒化镓晶体进行了研究,在硫的掺杂量为0,0.01,0.14,0.26,0.37时,在0.2-2.0THz测得了GaSe1.S.的折射系数、...     

基于太赫兹时域光谱系统的爆炸物识别

描述了太赫兹时域光谱系统的原理和组成,研制了太赫兹时域光谱(0.1~3THz)系统。介绍了太赫兹时域光谱技术在爆炸物识别方面的优势及其特点,提出了爆炸物识别的数学模型和方法。采用太赫兹时域光谱系统测试爆炸物样品的特征吸收光谱并将其作为标准模板,然后将爆炸物置于土壤、水泥和塑料障碍物后,采用太赫兹时域光谱系统得到穿透障碍物后爆炸物的特征吸收光谱,并将其与标准模板比对,从而实现爆炸物的隔物穿透识别。实验得到爆炸物RDX的特征吸收光谱,其特征频率为0.82,1.70和2.40THz。实验还对不同厚度和种类障碍物下爆炸物RDX、CL-20、LLM-105和FOX-1进行了实验测试,结果表明:穿透障碍物后爆炸物可识别的特征吸收光谱与标准模板匹配得很好,证明根据爆炸物特征吸收光谱实现爆炸物匹配识别的方法是可行的。基于文中提出的太赫兹时域光谱系统可进一步开展爆炸物残留痕量探测识别和隔物技术研究。     

太赫兹光谱和成像应用及展望

作为近年来颇受科技界和各国政府重视的一个新兴学科和技术领域,太赫兹辐射具有不同于其它波段电磁波的许多独特性质,因而在物理、化学、生物、材料、医学、农业、国防和军事等领域具有广阔的应用前景.结合国内外研究和应用的现状,本文概述了太赫兹时域光谱、太赫兹成像以及太赫兹技术在物理学、化学、生物学和天文领域的应用和机遇,供广大同行参考.     

基于LabVIEW的太赫兹时域光谱数据处理

太赫兹波段位于红外与微波之间。太赫兹时域光谱技术是一种随着超快激光技术的发展而新兴的、非常有效的相干探测技术,其应用前景已为世界公认。目前各实验室使用的多是基于MatLab和Origin软件处理太赫兹光谱实验数据,但这难以与数据采集程序相结合,所以迫切需要一种更加简便快捷的数据分析手段以适应太赫兹技术的发展。LabVIEW作为一种图形化编程语言具有许多优势。本文概述了太赫兹技术及太赫兹时域光谱,介绍了利用LabVIEW提取太赫兹时域光谱数据并进行分析的方法,通过实例并与其它两种工具处理的结果进行了比较,三种方法的结果完全吻合,证明了这种方法的可靠性。与数据采集程序相结合,我们的工作为太赫兹光谱实验提供了有力的数据分析工具。     

原油中硫含量的太赫兹时域光谱检测

原油中硫含量的快速检测对于原油的安全生产、运输、加工和环境保护均具有十分重要的意义.本文运用太赫兹时域光谱技术对不同硫含量的原油进行了实验测量,经过计算得到了样品的吸收谱和折射率谱.通过对这些光谱进行分析,结果表明太赫兹时域光谱不仅能够有效的检测出原油中的硫含量,还能实现对原油中物质的溶解程度进行定性的预测.     

基于太赫兹光谱的天冬氨酸结构分析及鉴定

太赫兹时域光谱技术（THz-TDS）是一种新的远红外波段光谱测量技术,对化合物结构上的微小差异变化十分敏感,因此成为物质分析与检测的新型方法。文章基于太赫兹时域光谱技术的测定方法,在氮气环境中考察不同来源天冬氨酸在太赫兹波段的吸收特性,并结合差示扫描量热仪（DSC）和傅立叶变换红外光谱仪（FITR）进一步验证THz测定结果的有效性。实验结果表明,用太赫兹时域光谱技术可以清楚地分辨出不同结构天冬氨酸的差异,方法简单,快速,准确。     

低温条件下汽车发动机润滑油的太赫兹时域光谱研究

采用太赫兹时域光谱技术研究润滑油的低温性能。在自建的透射式太赫兹时域光谱系统上,检测几种润滑油在-40~0 ℃间的太赫兹时域谱,并通过对太赫兹时域谱的处理得到润滑油的吸收系数和折射率。结果表明,低温导致润滑油中烃类物质结晶析出,使得润滑油黏度增大并且丧失流动性;温度降低对润滑油的影响在太赫兹时域光谱图中表现为时间延迟增大,温度与时间延迟表现出一定规律性;温度降低导致润滑油折射率增大,吸收系数增大,折射率与温度变化也呈现出相关性。研究证明太赫兹时域光谱技术能十分有效地检测温度变化对润滑油的影响,可用于研究润滑油的低温性能。     

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.