激光等离子体X射线能谱诊断

为了诊断激光装置聚爆靶辐射等离子体内部的分布及运动过程,搭建了基于球面弯曲晶体的能谱成像系统。该系统的核心元件为弯曲半径为200mm的石英球面弯曲晶体(1011),利用晶体的晶格结构进行反射,利用弯曲表面实现聚焦。在中国工程物理研究院神光Ⅲ原型激光装置上利用该能谱成像系统首次进行X射线能谱成像实验。IP成像板得到了清晰的高Z元素Au等离子体X射线能谱。能谱信息分析显示,石英球面弯曲晶体得到的能谱分辨率约为1 380,与能谱分辨模型理论值的误差为3.9%。该结果表明石英球面弯曲晶体具有很好能谱分辨能力。     

X射线单色成像用透射式对数螺线晶体分析器

利用对数螺线晶体在大视场范围内的保角特性,研究了一种用于等离子体X射线单色成像的透射式对数螺线晶体分析器。与反射式弯晶成像谱仪相比,该分析器具有单能成像视场更大,实现相同放大倍数时的空间排布简单等优点。根据晶体衍射成像原理及对数螺线晶体的表面方程,分析了透射式对数螺线晶体分析器的成像原理以及成像性能,包括子午、弧矢放大倍数以及视场大小等。以铜靶X射线源为背光源,用研制石英晶体透射对数螺线分析器对网丝直径为100μm的金属网格进行了单色背光成像实验。实验结果表明,晶体分析器的空间分辨力约为30μm,子午和弧矢方向视场分别达到15.938 7mm和5.900 6mm。     

激光等离子体X射线极化光谱研究

为了诊断激光等离子体X射线的极化光谱,研制了一种新型的基于空间分辨的极化谱仪。将平面晶体和球面弯晶色散元件在极化谱仪内正交布置,即在水平通道用PET平面晶体作为色散元件,而在垂直通道用Mica球面弯晶作为色散元件,球面半径为380mm。信号采用成像板进行接收,有效接收面积为30×80mm,从等离子体光源经晶体到成像板的光路约为980mm。物理实验首次在中国工程物理研究院激光聚变研究中心“2×10J激光装置”上进行,成像板获得了铝激光等离子体X射线的光谱空间分辨信号。实验结果表明该谱仪具有较高谱分辨率,适合激光等离子体x射线极化光谱的诊断。     

基于等离子体激光的X射线弯晶谱仪研究

X射线光谱议是一种强有力的激光等离子体诊断工具。为了获取激光等离子体发射的X射线中所包含大量信息,基于椭圆几何原理设计制造了X射线弯晶谱议。在上海神光 号装置上利用LiF弯曲晶体分析器,用150J激光能量对Ti靶进行了试验。通过X射线CCD记录获取的谱线,结果表明这种聚焦型晶体分析器的灵敏度有了明显的提高。     

大曲率弧矢弯曲复合晶体的研制

为提升国家同步辐射实验室X射线吸收精细结构(NSRL-XAFS)的光束线性能,提出将现有双平面晶单色器改造成弧矢聚焦双晶单色器的思想。采取将晶体与钛合金复合的工艺,实现了晶体的大曲率弹性弯曲,并将其用作弧矢聚焦晶体单色器中第二晶体的成像元件。鉴于NSRL-XAFS实验的光学要求,设计制作了复合晶体试验模型,通过有限元分析计算和长程面形仪实际测量得到了不同弯曲半径下晶体的面形精度,并用激光模拟其聚焦性能。结果表明,在缩放比为1/3时,样品上的成像束斑水平尺度(FWHM)由43mm(无聚焦)缩小到3mm,光子密度提高了近一个量级。这些结果满足NSRL在现有光源条件下提升XAFS数据采集质量的要求。     

一种新型曲面晶体成像系统的研制

为了对诊断目标进行瞬态辐射成像,提出了研制X射线聚焦成像系统,主要器件为一各向同性的X射线点光源及超环面弯曲晶体成像器.X射线照射至被成像物体后再投射到超环面晶体,经该凹面晶体聚焦后在X射线探测器表面成像.讨论了超环面晶体在布拉格几何结构中的聚焦成像特性,提出利用X射线源进行二维优化成像的适用条件.利用模拟软件对网格物体进行仿真成像,研究像距及光源尺寸对成像空间分辨力的影响,并据此确定了实验参量.设计的超环面弯晶采用云母材料,子午面曲率半径为290 mm,弧矢面曲率半径为190 mm.利用该系统进行了X射线背光成像实验,实验结果表明:系统的成像空间分辨力最高可达到34μm,能够满足聚爆辐射成像的要求;在光源尺寸较大时像距变化对成像效果有明显影响.     

氟化锂椭圆弯晶分析器的特性及应用

设计了测试能量范围为0.6~6 keV的椭圆弯晶谱仪。此谱仪利用椭圆自聚焦原理,晶体分析器采用氟化锂材料,椭圆焦距为1 350 mm,离心率为0.958 6,布拉格角范围为30~65°。在神光Ⅱ靶室进行了实验,入射激光波长为0.35 μm,激光功率约为1.6×10¹⁴ W/cm²,与厚度为100 μm的钛平面靶法线夹角约为45°。实验结果证实,弯曲的氟化锂晶体具有极佳探测效果,弯晶分析器对波长为0.2~0.35 nm的X射线的分辨率可达500~1 000,同时具有等光程而便于空间分辨测量的优点,在同样距离条件下比平晶分析器高一个数量级的收光效率,故适合于激光等离子体X射线的光谱学研究。     

椭圆弯晶谱仪分析器研制

针对激光惯性约束核聚变辐射的X射线分析,可得到关于等离子体电子密度、温度、电荷分布等重要信息.研究的X射线弯晶谱仪分析器是用来诊断X射线光谱,进而实现对激光惯性约束核聚变的控制.探讨了椭圆弯晶谱仪理论原理,分析了积分反射率和质量吸收系数.弯晶谱仪采用LiF弯晶分析器,椭圆焦距2c为1 350 mm,椭圆离心率e为0.958 6,晶体布拉格角范围为30°至60°.在此对LiF弯晶分析器的制作工艺进行详细描述.实验结果表明,该晶体分析器对X射线的分辨率(λ/Δλ)可达900以上,能够用来对激光等离子体的X射线光谱进行诊断.     

用修正双晶技术诊断激光等离子体X射线极化度

研制了激光等离子体极化光谱仪,用于诊断波长为0.2～20 nm的激光等离子体X射线的极化度并推断等离子体内部的各向异性状态.设计的谱仪在电子束垂直入射面内正交布置的色散元件均为PET晶体,两通道均用成像板接收光谱信号,其有效面积为30 mm×80 mm,从光源经晶体到成像板的光程分别为980mm和310 mm.在中国工...     

弯晶X射线光学

近年来,人们付出很大精力研制新的具有独特性能的同步辐射装置和自由电子激光器,而飞秒激光等离子源可提供具有高峰值亮度的超短X射线脉冲,用来作为波荡器辐射的补充X射线源。此外,所有最新型的X射线源的诊断和应用也都需要专用X射线光学元件或仪器。X射线光谱测量是激光聚变应用中最重要的等离子诊断方法之一,该方法根据实验目的,可获得单色X射线图像或与空间或时间分辨相组合的高分辨率图像。已经研制出拥有多达10个环状弯晶的高精单色成像仪,用以研究激光聚变实验中的内爆过程并通过获得的数据对等离子体参数的时间分辨图做出评估。大功率飞秒激光器可提供实用的相对价格不高的大功率X射线脉冲源,但需要有发光效率,能量分布,以及热电子传输方面的信息来实现理想K层辐射线或者连续X射线输出的最大化,以便得到相当于同步辐射输出的峰值亮度。把这些新的射线源与弯晶光学元件相组合,可完成亚皮秒时间量级的衍射实验。激光泵浦的X射线探针实验已经展示了若干晶体在250 fs内的结构变化。作者所在研究所使用光线追踪和布拉格反射方法设计了1D或2D或1D与2D结合的弯晶X射线光学仪器。在仪器制备过程中,非常注重晶体完整,反射选择的优化,弯曲精确,以及成像和反射特性的测量,还使用X射线形貌相机和衍射仪对分析器晶体的相关特性做了测试。     

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.