全三维电离粒子有源像素探测器优化仿真

提出了一种双外延高能离子注入的单片集成有源像素探测器的传感器结构,以提升传感器对电荷的收集性能和辐射加固,并进行了三维工艺模拟和物理级器件仿真计算.研究结果表明,所提出的传感器结构改善了内部电场和电势的分布,且目标电极的电荷收集效率提高70%,电荷收集时间减少64%.此外,当等效中子辐射流通量在1012—1015cm-2范围内时,所提出的传感器结构比标准传感器结构有更高的电荷收集能力.     

Development of fast,simultaneous and multi‐technique scanning hard X‐ray microscopy at Synchrotron Soleil

A distributed fast‐acquisition system for synchronized multi‐technique experiments is presented, in which the collection of metadata and the asynchronous merging of large data volumes from multiple detectors are managed as part of the data collection process. This fast continuous scanning scheme, named FLYSCAN, enables measurement of microscopy data on a timescale of milliseconds per pixel. Proof‐of‐principle multi‐technique experiments, namely scanning X‐ray fluorescence spectrometry combined with absorption, differential phase contrast and dark‐field imaging, have been performed on biological and geological samples.     

Target extraction from blurred trace infrared images with a superstring galaxy template algorithm

Accurate and efficient targets extraction from blurred trace infrared images has very important meaning for latent trace evidence collection in crime scene. Based on the superstring theory, a superstring galaxy template extraction algorithm for infrared trace target is presented. First, all of the pixels are divided into three classes: target pixels, background pixels and blurred pixels. Next, the superstring template characteristics for every pixel in a blurred infrared image are calculated as the features of each pixel. Finally, a galaxy covering algorithm is proposed, target pixels and background pixels are used for training the galaxy covering domain of every galaxy classifiers, and these classifiers will divide each blurred pixel into two classes: a target pixel or a background pixel. Experimental results indicate that the superstring galaxy template algorithm can improve the target extraction rate and reduce the extraction error rate.     

平面场景和建筑物成像的几何分析

为了识别采集图像中的平面场景以及建筑物,利用摄像机参数,对平面场景及建筑物成像过程进行了几何分析。首先,根据相机参数以及相机飞行状态分析平面场景成像畸变;然后,对平面场景上的建筑物形状的成像进行几何分析;最后,将相机上采集到的平面场景及建筑物的图像像素数与真实平面场景及建筑物的尺寸建立联系。实验结果表明:已知相机参数及飞行状态的情况下,可以对平面场景及建筑物形状信息进行推导,从而完成目标识别与跟踪。本方法适合在典型建筑物、孤立建筑物、建筑群中具有明显形状特征等情况下对立体目标进行自动捕获与跟踪。     

Fast Computation of Fresnel Holograms Employing Difference

We propose an approximation method that can calculate the Fresnel hologram 16 times faster than the conventional method. To compute the hologram, an object is assumed to be a collection of self-illuminated points and the fringes from each object point are superposed. The distance between object point and sampling point on the hologram is used to obtain the phase of the light. Since a sampled hologram usually has small pixel intervals, the difference of the distance values between adjacent pixels is also small and its n-th order difference can be assumed to be constant. Therefore, the distance value at a certain pixel can be obtained from its neighbor with simple additions. The distance error can be reduced less that one wavelength with practical parameters. A hologram, which has a horizontal parallax only, 1.3 Mega-pixels and 1,000 object points, can be calculated in less than one second with a personal computer.     

CW laser-induced fluorescence of toluene for time-resolved imaging of gaseous flows

A laser-induced fluorescence diagnostic is presented for high-speed measurements in gaseous flows. The technique employs a toluene tracer excited at 266 nm by a cavity-doubled 532 nm diode-pumped 5.5 W CW laser. The high power (600 mW) of UV light produced by cavity doubling, together with the high fluorescence yield of toluene, yields strong signal levels needed for high-speed recording. Fluctuation detection limits for tracer mole fraction were investigated by applying the diagnostic to an atmospheric temperature and pressure nitrogen jet. For single-point measurements with a photomultiplier tube, the detection limit for fluctuations in the toluene mole fraction was 0.028%, achieved with 430 mW of laser power and 8.5 kHz bandwidth for a 1×0.4×0.4 mm collection volume. Line (1-D) imaging with a kinetic-readout camera (512 pixels/row) achieved a detection limit of 0.23% with 440 mW of laser power, 9.7 kHz frame rate, and 0.3×0.2×0.4 mm collection volume per pixel, while planar (2-D) imaging with a 512×512 pixel intensified camera achieved a detection limit of 0.88% with 205 mW of laser power, 100 μs exposure time, and 0.4×0.4×0.4 mm volume per pixel. Line and planar imaging were applied to a turbulent jet with Re of about 10000.     

利用图像处理实现平面工作台三自由度位移的同步检测

为了实现平面工作台三自由度位移的同步检测 ,研制了图像处理位移检测系统。以CCD相机为核心 ,结合显微镜放大、图像采集和图像处理构成检测系统。图像处理软件用VC编制 ,计算并绘制了工作台三自由度位移随时间的变化关系 ,以及工作台在平面内的运动轨迹。系统的位移检测不受工作台大幅转动的影响。检测系统达到了亚像素级的位移分辨率。选择合适的显微镜放大倍率 ,可使检测系统既有较高的位移分辨率 ,又有一定的位移检测范围     

平面场景和建筑物成像的几何分析

为了识别采集图像中的平面场景以及建筑物,利用摄像机参数,对平面场景及建筑物成像过程进行了几何分析。首先,根据相机参数以及相机飞行状态分析平面场景成像畸变;然后,对平面场景上的建筑物形状的成像进行几何分析;最后,将相机上采集到的平面场景及建筑物的图像像素数与真实平面场景及建筑物的尺寸建立联系。实验结果表明：已知相机参数及飞行状态的情况下,可以对平面场景及建筑物形状信息进行推导,从而完成目标识别与跟踪。本方法适合在典型建筑物、孤立建筑物、建筑群中具有明显形状特征等情况下对立体目标进行自动捕获与跟踪。     

A fast T1 algorithm.

Multispectral tissue classification using magnetic resonance T1, T2, and rho images may be useful in diagnosing and locating certain pathology. Techniques for generating the T1 images necessary for this classification scheme often require longer data collection and post processing times than are practical. As a consequence, further development of this classification scheme may be limited. This paper addresses an improvement in the post processing time required to generate T1 images. A nonlinear least-squares algorithm is described for rapidly generating spin-lattice relaxation time images from variable repetition time magnetic resonance images. The algorithm generates a 256 x 256 pixel T1 image from nine variable repetition time images in approximately 60 sec on a VAX-6510 computer.     

一种基于自适应权值的立体匹配方法

提出了一种新的自适应权值的立体匹配方法,在匹配中无需逐像素确定其支持窗口的尺寸。首先根据像素间的相似性和邻近性对匹配窗口内每一像素的支持权值进行调整,使与待匹配点位于同一区域的像素权值增大,然后在匹配的代价函数中引入视差平滑性约束项,从而获得最终视差。在Middlebury提供的标准图像上进行了测试。实验结果表明,该方法可以获得良好的视差图。     

数字图像直线特征的亚像素位置检测

根据像素点的梯度方向和直线局部特性提出了一种新的亚像素直线特征检测方法。图像中具有相同方向的直线上的点具有相近的梯度方向。因此首先根据边缘点的梯度方向把它们划分为不同的点集;然后在同一点集中扫描得到组成每一直线各自的像素点;再然后根据直线上局部小邻域内像素灰度分布特性,在直线上边缘点的3×3邻域内得到其中的线段解析表达式;最后通过判断在小邻域内所得线段和由边缘点拟合得到直线的位置关系,在线段上得到亚像素精度的拟合点,进一步拟合得到高精度的直线特征位置。实验表明,这种方法的定位精度可以超过0.05像素,角度定位精度超过0 02°,并且具有较好的实时性。     

质心检测不确定度的估计方法

提出了一种估计质心检测不确定度的新方法.首先由像素强度和像素所在位置的图像梯度估计像素强度的不确定度,然后由像素强度不确定度的估计值和像素之间的相关性确定质心检测的不确定度.给出了估计像素强度不确定度的数学模型和估计质心检测不确定度的解析表达式.实验结果表明.用该方法能准确地估计质心检测结果的不确定度.     

分子超光谱成像系统及其生物医学应用

设计出一种基于AOTF(acousto-optic tunable filters)的分子超光谱成像系统(MHSI).整个系统由显微镜、分光计、CCD镜头、数据采集卡和计算机等几部分组成.系统的光谱范围为550～1 000 nm,可采集225个波段,光谱分辨率优于2nm,空间分辨率达到0.3μm.由于系统的光源对样本的...     

基于物联网的人工智能图像检测系统设计与实现

物联网络的建立促使人工智能领域取得飞跃性进展。传统图像检测方法利用小波能算法进行背景与边缘噪声划分方式进行图像检测,存在低分辨率图像检测精度低、检测速度慢、缺乏图像深度分析等一系列问题。物联网人工智能发展迅速的环境下,提出基于物联网的人工智能图像检测系统设计。采用智能人工像素点特征采集技术(IAPCCT),对图像进行逐点特征提取,运用物联网丰富数据量资源与处理运算能力对采集图像像素点进行特征分析回馈,回馈信号经人工智能信号图像合成模块(AISIS),对信号做图像转换处理并输出分析结果完成图像检测。通过仿真实验测试证明,基于物联网的人工智能图像检测系统设计具有图像检测率高、识别准确度高、运行稳定、处理高效等优点。     

基于立体像素匹配的图像重构技术研究

为了解决目前全景成像技术中分辨率低的问题,提出了一种新的基于3D场景立体像素光线映射的全景图像计算机重构技术.在全景成像技术中,3D场景的每个立体像素点经全景成像系统的编码系统分别映射在一定区域的多个体元素图像的不同像素点上.在计算机重构全景图像时,根据逆光学路径原理,提出了从立体像素映射到的体元素图像区域中提取对应立体像素的多个2D像素点来重构全景图像,使重构的全景图像最大分辨率可达到传统成像方法图像分辨率的N倍（N为映射区域面积）.提出的立体像素的匹配技术大大提高了重构的计算机全景图像分辨率.     

Fast‐scanning high‐flux microprobe for biological X‐ray fluorescence microscopy and microXAS

There is a growing interest in the biomedical community in obtaining information concerning the distribution and local chemical environment of metals in tissues and cells. Recently, biological X‐ray fluorescence microscopy (XFM) has emerged as the tool of choice to address these questions. A fast‐scanning high‐flux X‐ray microprobe, built around a recently commissioned pair of 200 mm‐long Rh‐coated silicon Kirkpatrick–Baez mirrors, has been constructed at BioCAT beamline 18ID at the Advanced Photon Source. The new optical system delivers a flux of 1.3 × 10¹² photons s^?1 into a minimum focal spot size of ～3–5 µm FWHM. A set of Si drift detectors and bent Laue crystal analyzers may be used in combination with standard ionization chambers for X‐ray fluorescence measurements. BioCAT's scanning software allows fast continuous scans to be performed while acquiring and storing full multichannel analyzer spectra per pixel on‐the‐fly with minimal overhead time (<20 ms per pixel). Together, the high‐flux X‐ray microbeam and the rapid‐scanning capabilities of the BioCAT beamline allow the collection of XFM and micro X‐ray absorption spectroscopy (microXAS) measurements from as many as 48 tissue sections per day. This paper reports the commissioning results of the new instrument with representative XFM and microXAS results from tissue samples.     

基于逐行处理的高光谱遥感异常快速检测方法

针对基于逐像元处理的因果实时异常(Causal Real-time Relationship Reed-X Detector,CR-RRXD)检测算法计算量大,以及基于逐像元方式边检测边成像显示的时间过长而不能满足快速处理要求的缺陷,提出了一种基于逐行处理的CR-R-RXD检测算法.与基于逐像元处理的CR-R-RXD检测算法相比,该方法将高光谱图像整行像元向量作为输入,即处理一行高光谱数据只需计算一次,极大地减少了计算次数.实验结果表明,与R-RXD和基于逐像元处理的CR-R-RXD算法相比,本文算法可在获得与R-RXD算法几乎相同的检测准确度的情况下,实现快速实时处理,其检测准确度相较于基于逐像元处理的CR-R-RXD算法有所提高,且算法检测时间大大缩短,增强了算法的时效性.     

公共格栅像素CdZnTe探测器的能谱特性

使用同一块CdZnTe晶体设计制作了像素大小不等的4×4公共格栅像素CdZnTe探测器。通过能谱测定实验及权重势和电场仿真,研究了公共格栅像素CdZnTe探测器中的小像素效应和引导效应。结果表明:由于小像素效应较弱,较大的像素不能有效消除"空穴拖尾",能谱特性较差;由于晶体内部以及像素和公共格栅间隙表层的电荷损失,较小的像素能谱特性也较差。在像素宽度为0.8 mm时,得到了对662keV的137Cs放射源的最佳能量分辨率3.80%和峰谷比5.65。适当增大公共格栅偏压可以引导电子向阳极像素运动,促进电荷的完全收集,改善探测器的能谱特性。过大的偏压则会造成像素和公共格栅间表面漏电流的增加,探测器的能谱特性也会恶化。在像素宽度为0.8mm时最佳偏压为-60V。     

角点检测不确定度评定方法

 提出一种评定角点检测不确定度的新方法。建立了一个像素强度不确定度数学模型,该数学模型在像素强度不确定度与像素强度和图像梯度之间建立了联系。给出了实现角点检测不确定度评定的具体方法：首先利用像素强度不确定度数学模型估计每个参与角点检测的像素的强度不确定度,然后再用蒙特卡罗方法估计出角点检测的不确定度。以经典SUSAN角点检测算子为例,对文中提出的角点检测不确定度评定方法进行了验证。实验结果表明,使用该方法能准确地估计出角点检测结果的不确定度。     

Two-dimensional simulations of plasma flow and charge spreadingacross barrier pixels in AC plasma displays

Two-dimensional multispecies simulations of adjacent pixels separated by a barrier height 80% the gap height in a plasma display pixel cell are performed. The fill gas pressure is 400 torr with 2% xenon in helium. The simulations using a minimum number of excited states of helium and xenon are performed for different cell widths representing different display resolutions. The simulations show plasma transport through the gap to the adjacent pixel which is in the sustained off state. In a sustained off state, there is no discharge in the pixel at the sustained voltage. The simulations show that for low-resolution displays, the plasma overflow does not cause a discharge in the adjacent pixel that is in the sustained off mode, while for a high-resolution display a 20% gap in the barrier height could result in a breakdown in the adjacent off pixel. A higher pixel resolution, or equivalently smaller pixel pitch. requires higher firing and sustained voltages due primarily to increased particle losses as a result of the reduced particle transit times. Finally, using a larger number of excited xenon atomic states including the xenon [6s, j=1] and [6s', j=1] radiative states and the molecular xenon dimer, an isolated single pixel is simulated to model the transport of excited states including the radiative states. The model shows that the density profiles peak in the cathode fall region spreading out to the side walls with decreasing intensity