国家雷电监测网的建设与技术分析

雷电是一种对自然环境和社会经济都会造成很大影响的自然现象。对其进行有效的监测、预测和研究具有十分重要的社会、经济与科学价值。目前我国在雷电监测、预测和研究方面还比较薄弱，特别是在监测领域，与发达国家有较大差距。文章对雷电产生的原因及影响做了介绍，对国内外目前的探测技术及发展方向进行了分析，提出了国家雷电监测网建设应注意的问题和建议     

A photothermocapillary method for detecting delamination of paint and varnish coatings

The photothermocapillary (PTC) method proposed previously [9] for detecting near-surface inhomogeneities hidden under paint and varnish coatings is developed so as to also reveal defects in these coatings. We have measured the PTC response signal from the sites of coating delamination modeled as 1.4-mm-wide gaps formed by two (3 + 3 mm long) steps with the heights of 10, 20 and 20, 30 μm and as holes with diameters of 1.4 mm and depths of 0.5 and ∼2 mm in copper and duralumin plates, respectively. The results of experiments confirm the ability of the proposed PTC method to determine with good precision both the lateral dimensions of delamination regions and the heights of air gaps.     

广义边缘CWD-Hough变换在宽带声成像中的应用

提出了一种基于广义边缘CWD—Hough（GMCWD—Hough）变换的宽带声成像方法。分析了基于时间伸缩-时延的宽带相关声成像的基本模型,介绍了广义边缘CWD—Hough变换。根据目标回波的时频分布特点,该方法基于时间一频率联合分析法,提取信号在时频域的分布特性参数进行时间伸缩时延的声成像。通过设计合理的广义边缘核函数,能有效避免常用的WVD方法产生的交叉项影响,检测性能优于常用的Wigner—ville分布方法。实验结果表明该声成像方法的有效性,不仅适合水声宽带成像,而且对于低信噪比条件下的其它成像方式也具有参考价值。     

A Functional CT Contrast Agent for In Vivo Imaging of Tumor Hypoxia

Hypoxia, which has been well established as a key feature of the tumor microenvironment, significantly influences tumor behavior and treatment response. Therefore, imaging for tumor hypoxia in vivo is warranted. Although some imaging modalities for detecting tumor hypoxia have been developed, such as magnetic resonance imaging, positron emission tomography, and optical imaging, these technologies still have their own specific limitations. As computed tomography (CT) is one of the most useful imaging tools in terms of availability, efficiency, and convenience, the feasibility of using a hypoxia‐sensitive nanoprobe (Au@BSA‐NHA) for CT imaging of tumor hypoxia is investigated, with emphasis on identifying different levels of hypoxia in two xenografts. The nanoprobe is composed of Au nanoparticles and nitroimidazole moiety which can be electively reduced by nitroreductase under hypoxic condition. In vitro, Au@BSA‐NHA attain the higher cellular uptake under hypoxic condition. Attractively, after in vivo administration, Au@BSA‐NHA can not only monitor the tumor hypoxic environment with CT enhancement but also detect the hypoxic status by the degree of enhancement in two xenograft tumors with different hypoxic levels. The results demonstrate that Au@BSA‐NHA may potentially be used as a sensitive CT imaging agent for detecting tumor hypoxia.     

实时监控系统中运动人体图像分割

在运用差图像算法进行运动人体检测、噪声消除的基础上，提出了将统计直方图与梯度边缘检测相结合的算法以消除运动人体的影子；同时运用图像扩展模板并配合图像边界处平滑的算法对被分割人体的断裂处进行连接填充。实验结果验证了上述算法对噪声抑制、人影消除以及人体图像断裂处填充的有效性。     

Direct and real-time visualization of the disassembly of a single RecA-DNA-ATPgammaS complex using AFM imaging in fluid

RecA disassembly from circular double-stranded DNA (dsDNA) was studied by atomic force microscopy (AFM) imaging in fluid on a single molecule scale. The RecA/DNA complex was formed in the presence of ATPgammaS, and the disassembly was then initiated by buffer exchange to rinse off ATPgammaS. Performing AFM imaging in fluid allowed direct and real-time visualization of the disassembly of RecA from dsDNA in solution. It was found that RecA disassembly commenced from multiple sites both in deionized water and in buffer; the areas where RecA dissociated showed the appearance of "gaps" in the filamentous structure. RecA further disassembled either through the already existing "gaps" or by generation of new gaps. The disassembly was slower in buffer than in deionized water, suggesting that ions also contribute to the stabilization of the complex. RecA hexamers and monomers were observed in deionized water and in buffer, respectively, during the disassembly process.     

高压水表裂纹成像检测技术研究

本文介绍一种检测高压水表裂纹的技术,该技术通过IP成像板采集头部X射线扫描生成的图像数据,然后利用软件成像技术处理图像数据,从而实现检测识别裂纹的功能。     

一种基于X射线成像系统医疗设备技术的研究

G形臂X射线成像系统(以下简称"G形臂")集移动性G形臂与X线成像系统于一身,是一种基于X射线成像系统的新医疗设备技术,填补了国内同类产品空白,顺应我国战略新兴产业发展方向。G形臂相较于传统C形臂X射线成像系统,因其独特的设计、工艺、创新,应用于手术,具有精度高、风险相对低、手术时间短、出血少、麻醉需求量少、感染发生机率较低等优点,具有不可比拟的临床优势。     

Representation of non-stationary time series of significant wave height with autoregressive models

A time series of significant wave height measured at the Frigg Platform, in the North Sea is modelled using Box-Jenkins autoregressive models. As this series is non-stationary two different transformations are performed and compared. Since this type of data has several gaps, the whole series was divided into subseries with no gaps which allows piecewise modelling of the initial set. Very similar statistical properties among these subsets were observed and very similar models were obtained. This allowed the derivation of one autoregressive model which would describe adequately the whole data set.     

一种新的超声成像方法振动声成像

文章介绍一种新的超声成像方法———振动声成像。首先从理论上分析了振动声成像的基本原理;然后分别介绍了该方法在钙化动脉血管成像、乳房中微钙化灶的检测以及受热疗和HIFU治疗的肿瘤组织焦斑检测等方面的应用;最后比较了振动声成像与传统超声成像不同点并指出了振动声成像独特的优势。     

Electrical stability of polyimide siloxane films for interlayer dielectrics in multilevel interconnections

Electrical stability of a polyimide siloxane (PSI) film for ultra-large scale integrated circuit (ULSI) multilevel interconnections is studied. The PSI films, modified by p-aminophenyltrimethoxysilane (APTMS), are designed to have three-dimensional polymer structures through Si–O bonds. It has been revealed that the PSI films are more stable in electrical properties at higher temperatures than 150°C, as compared to the conventional polyimide (PI) films. The electrical conduction mechanism study for the PSI films has revealed that Schottky emission is dominant. Barrier height φ_B obtained from the electrical property for the PSI film was 0.460 eV in the temperatures ranging from 25–250°C. On the other hand, barrier height of 0.422 eV at lower temperatures than 150°C and activation energy of 1.09 eV at higher temperatures than 150°C were obtained for the conventional PI film. The difference in polymer structure is very sensitive to the electrical conduction at high temperature, due to sodium ion migration. The ideal band diagrams of metal-insulator-semiconductor (MIS) structures were also discussed. The optical band gaps for PSI and conventional PI films were 3.320 eV and 3.228 eV, respectively. This result suggests that the band gap of PI films can be enlarged by modification with Si–O components. The differential barrier height between the PSI and conventional PI films is 0.038 eV, and is close to the difference in half of optical band gaps (0.046 eV).     

EMCCD用于空间生物光成像探测的可行性分析

生物光检测技术在地面的应用日益广泛,而空间生物光检测技术还处在对光强较强的生物光检测的阶段.空间生命科学研究的持续发展对微弱生物光检测技术提出需求.本文对比分析几种微弱光探测技术,总结了EMCCD在空间应用的技术优势,并提出了基于EMCCD的空间微弱生物光成像检测系统的方案.从目标亮度、探测器光敏面照度及探测器制冷等角度分析了弱信号的获取和系统信噪比,对基于EMCCD技术的空间生物光成像检测系统的可行陛和检测能力进行了分析论证.     

Model for Estimating the Heterogeneity of the Distribution of Globule Characteristics in Images of Skin Neoplasms

Measurement Techniques - The problem of diagnosing skin melanoma by digital imaging of the tumor is considered. Clinical algorithms for detecting skin melanoma are briefly described. A review of...     

Analytic diffraction analysis of a 32-m telescope with hexagonal segments for high-contrast imaging

Large segmented telescopes cannot be modeled accurately with fast-Fourier-transform techniques since small features such as gaps between the segments will be inadequately sampled. An analytic Fourier-transform method can be used to model any pupil configuration with straight edges, including tolerance analysis and some types of apodization. We analytically investigated a 32-m segmented primary with 18 hexagonal segments for high-contrast imaging. There are significant regions in the image in which extrasolar planets could be detected. However, the hexagonal profile of the pupil was not as useful as expected. The gaps between the segments, the secondary obscuration, and the secondary spiders must be as small as possible and their edges must be apodized. Apodizing the edges of the individual segments reduced the useful regions in the image since the gaps appeared to be wider.     

纳米金在肿瘤诊断中的应用

纳米金具有独特的理化性能,在肿瘤诊断和治疗中取得了许多重要进展。综述了纳米金的结构组成、粒径尺寸、形貌特征对其本身性能的影响,介绍了纳米金对肿瘤标志物的检测和作为造影剂对肿瘤成像的研究进展,着重评述了纳米金应用于体内外肿瘤光学成像方面的研究情况,展望了其未来的发展前景。     

Non-destructive Imaging of Standard Cracks of Railway by Photoacoustic Piezoelectric Technology

The photoacoustic piezoelectric (PAPE) technique is an effective non-destructive testing technique for detecting defects in materials. In this paper, Chinese national standard railway cracks have been detected by thermal wave imaging based on the PAPE technique. First, the theory of the PAPE technique has been introduced and the corresponding imaging principle has been analyzed. Second, the corresponding experimental system has been setup, and the imaging tests have been carried out. Third, two kinds of standard cracks have been examined by the imaging system. The results show that thermal wave imaging based on the PAPE technique can effectively image and identify the cracks at different depths, which lays a foundation for practical application to the detection of rail cracks.     

Stereopsis-Inspired 3D Visual Imaging System Based on 2D Ruddlesden–Popper Perovskite

Stereopsis is of great important functions for humans to perceive and interact with the world. To realize the function of stereoscopic imaging, optoelectronic sensors shall possess good photoresponsive performance, multidirectional sensing, and 3D building capabilities. However, the current imaging sensors are mainly focused on 2D imaging, limiting their practical application scenarios. In this study, a stereopsis-inspired flexible 3D visual imaging system (VIS) based on 2D Ruddlesden–Popper perovskite is demonstrated. The 3D-VIS consists of 800 device units, each of which demonstrates excellent photoresponse performance, mechanical characteristics, and environmental stability. In addition to the capability of detecting 2D reflective images, the 3D-VIS realizes the function of detecting the depth of field and fusing object projections of two directions to invert the 3D image by utilizing voxels to rebuild the spatial structure of the object. In the future, the 3D-VIS will have broad application prospects in medical imaging, virtual reality, industrial automation, and other fields.     

双目凝视系统中运动点目标实时检测算法

通过双目凝视系统视场重叠区进入系统的信息量大于通过非重叠区进入系统的信息量,根据这一特征,建立了应用于双目凝视系统的运动点目标并行实时检测算法。算法采用差分向量范数法对原始图像序列做预处理,去掉大量低频噪音和背景,采用光流场法从预处理后的图像中分离可疑运动点目标,再用提出的空间时间并行快速判定准则对分离的可疑运动点目标进行运动连续性和一致性判定,识别出真正的运动点目标。实验结果表明,建立的运动点目标检测算法的平均速度比单目视觉系统提高了50%,在图像信噪比不小于3dB时准确判定识别的概率为95%。     

LiF crystals as high spatial resolution neutron imaging detectors

Neutron imaging by color center formation in LiF crystals was applied to a sensitivity indicator (SI) as a standard samples for neutron radiography. The SI was exposed to a 5 mm pinhole-collimated thermal neutron beam with an LiF crystal and a neutron imaging plate (NIP) for 120 min in the JRR-3M thermal neutron radiography facility. The image in the LiF crystal was read out using a laser confocal microscope. All gaps were clearly observed in images for both the LiF crystal and the NIP. The experimental results showed that LiF crystals have excellent characteristics as neutron imaging detectors in areas such as high spatial resolution.     

Impact damage detection in composite plates using deflectometry and the Virtual Fields Method

This paper presents a new method for detecting damage in layered composite materials using a simple measurement technique, deflectometry. The aim is to locate the damage in a specimen and provide a “signature” from the measured surface slopes. Firstly, this method is applied to plate specimens using numerical and experimental data. Secondly, damage indicator based on a new application of the virtual fields method to compute local apparent gaps in equilibrium is presented and used to process the measurements on plates. It is shown that the damage indicator is very sensitive, allowing detection of damage that is difficult to identify directly from the strain maps.