Super-resolution reconstruction of images based on uncontrollable microscanning and genetic algorithm

Aiming at these disadvantages like lack of details, poor contrast and blurry edges of infrared images reconstructed by traditional controllable microscanning super-resolution reconstruction （SRR）, this paper proposes a novel algorithm, which samples multiple low-resolution images （LRIs） by uncontrollable microscanning, and then uses LRIs as chro- mosomes of genetic algorithm （GA）. After several generations of evolution, optimal LRIs are got to reconstruct the high-resolution image （HRI）. The experimental results show that the average gradient of the image reconstructed by the proposed algorithm is increased to 1.5 times of that of the traditional SRR algorithm, and the amounts of information, the contrast and the visual effect of the reconstructed image are improved.     

高速移动环境下无线信道的检测与估计

在高速移动的环境下,无线信道呈现快速变化的特征,导致对信道的估计难度增加。针对高速移动环境下的信道特征,提出一种新的信道估计方法,根据当前信道信息选取最佳负载因子,对时变信道进行更准确的估计。仿真结果证明了该估计算法的有效性。     

Towards a framework for high-speed communication in a heterogeneousnetworking environment

The issues that are specific to heterogeneous networks are addressed. Some background on both the current ARPA internet model and high-speed packet switching is provided. This discussion includes: the internet components; the internet protocol hierarchy, popularly known as the transmission control protocol/internet protocol (TCP/IP) protocol suite; and the internet strengths and weaknesses. The major elements of an extended internet model that allows internetworking of new high-speed packet networks with a wide range of other networks, including current data networks and national telephone networks, are outlined. Some end-to-end and host interface issues are examined     

VC环境下高速实时数据采集的实现

为了满足发动机试验工程背景的需要,研究了在VC＋＋环境下,利用多线程技术进行发动机高速数据采集系统的设计,对设计中的几个关键性技术进行了较为详细的研究,并给出了部分代码,试验证明该方案是可行的,并有一定的通用性。     

高速铁路环境下无线链路的一体化建模与分析

采用时域有限差分(FDTD)法和完全匹配层(PML)技术对高速铁路环境下的无线链路进行了一体化建模研究,较详细地模拟了更接近实际情况的机车模型以及电气化接触网导线、钢轨等高速铁路环境,通过数值模拟给出了高速列车处在铁路沿线不同位置时,机车顶部单极天线输出电压电流的变化规律.目的是研究包含机车复杂环境影响的空间入射场与天线输出电压电流的关系.结果表明:一体化建模与分析能够将空间场参数与真实天线的输入端的路参数联系起来,这是传统的电波传播研究方法难以做到的.     

非球面面形精细重构方法研究

针对非球面反射镜在抛光初期干涉仪不能全口径检测面形误差的问题,提出一种三坐标测量机(CMM)和数字干涉仪组合测量以实现全口径波前复原的方法.将CMM与干涉仪测量数据组合,即面形误差以干涉测量为主,干涉检测不能复原的局部波前采用CMM测量数据进行精细重构,从而获得可用于数字化加工的全口径面形误差,并最终达到非球面镜全口径干涉检测.采用该方法对Φ为540 mm的离轴非球面反射镜在精磨后期进行数据组合补偿,成功实现了反射镜从精磨阶段到抛光阶段的全口径波前检测,从而证明了该方法对实现非球面镜全口径检测有效可行.     

Optical excitation of surface plasmons

Described are the resonance effects associated with surface plasmon excitation (the excitation of evanescent electro-magnetic surface waves) which occur when light is reflected from metal gratings and rough surfaces.     

陆地高速移动环境下电波传播特性的建模与分析

采用有限状态的马尔克夫链得出陆地高速移动环境下电波传播路径的动态仿真模型。将模型与真实的陆地高速移动电波传播环境相结合,建立了更符合实际传播环境的电波传播仿真模型,通过该传播模型得出陆地高速移动环境下的电波传播特性。将得出的模型运用于较平坦地理环境,基站信号覆盖区域约为3km,存在视距(LOS)路径。通过仿真给出了高速列车在沿线不同位置和不同速度时的电波路径数目、各电波路径的衰减系数、延迟时间等,以及由此分析计算出的在该环境下的多普勒频谱、电平通过率等电波特性。最后,对这些仿真数据进行统计分析,证实了该传播模型的有效性。     

点钞机中纸币高速运动状态及轨迹重构试验

为清晰显示走钞姿态,以广州康艺TBYD-HT-9000系列点钞机为研究对象,将高速相机置于样机侧面对纸币在走钞机构中的运动状态进行实时捕捉、数据处理,将原始图片导入Auto CAD标定处理,可将纸币在不同结构参数走钞机构中的整个运动轨迹进行重构,进而研究该结构参数的变动对纸币运动时间和平顺性的影响。试验表明,在纸币即将离开滚轮轴时前缘的翘曲程度会因从动轮偏转角的不同而不同,当左偏转至10°时,纸币传输最平顺,传输时间最短,单张纸币传输时间最短为0.076 s。     

离轴抛物面镜像面扫描太赫兹光学设计

为了提高太赫兹成像速度,设计了一种像面扫描太赫兹快速成像系统。它为反射式单像素探测器成像,成像系统采用新设计的表面镀金的离轴抛物面镜结构以实现大口径、无遮拦、高反射率、高质量成像;反射成像系统光学设计F数为2.93,通光孔径为100 mm,视场为1,焦距为293.45 mm,成像窗尺寸为64 mm64 mm,圆孔直径为2 mm,扫描采集1616像素图像时间为0.1 min,3232像素图像时间为0.42 min,6464像素图像时间为1.7 min,空间分辨率为1 cm。扫描系统结合压缩传感成像理论采用新型像面扫描方法实现快速成像,在系统焦平面位置加入旋转多孔盘,对像面的图像进行太赫兹能量强度扫描,使用金属光锥收集能量到高莱探测器。利用压缩传感理论的特殊条件（采样数目与图像像素数相等）进行像面图像采集,然后利用正则归一化方程重构像面图像,该系统具有成像速度快、分辨率高、低成本、结构紧凑合理的优点。     

高速光纤通信中的光纤放大器及其发展

光纤放大器是高速光纤通信中的重要器件之一,文章综述了掺铒光纤放大器、掺铥光纤放大器、喇曼放大器、布里渊放大器、参量放大器以及混合光纤放大器等的工作原理、结构和工作特性,并对今后的发展方向进行了讨论.     

Optical adaptive equalization of high-speed signals using time-domain optical Fourier transformation

This paper describes a new distortion-free optical transmission method that can eliminate any kind of linear perturbation including jitter, polarization-mode dispersion, and higher order dispersion as well as time-varying dispersion. This method uses transform-limited pulses and time-domain optical Fourier transformation (OFT). With this technique, particular attention is given to the spectral envelope profile of the transmitted signal, which is unchanged regardless of the type and magnitude of the linear perturbation in the transmission fiber. OFT converts the unchanged spectral profile into the time domain and allows to obtain undistorted original waveforms at the output. Experimental and analytical results to show the effectiveness of this method are presented, especially when the method is applied to high-speed signals up to 160 Gb/s, which are sensitive to both higher order and time-varying dispersions. This paper also describes a new all-optical time-domain Fourier transformation technique that uses an optical parabolic pulse. This technique is promising, with a view to improving the elimination of distortion at 160 Gb/s and above.     

Optical assessment of a fouling-resistant surface (PHEMA/ benzalkonium chloride) after exposure to a marine environment

A hydrogel based on poly(2-hydroxyethyl methacrylate) (PHEMA) containing benzalkonium chloride (BAK) can be used as an environmentally acceptable, fouling-resistant material in the marine environment. The loaded hydrogel system is transparent and has the potential to be used in the protection of optical ports in underwater instruments. Ultraviolet–visible (UV–vis) spectroscopy was used to study the optical properties of the material after a marine exposure period. The optical transmittance of PHEMA/ BAK was higher for 10 weeks than that detected for poly(methyl methacrylate) (PMMA), a material currently used in commercial instruments, which confirmed the superior fouling resistance of the PHEMA/ BAK combination. The UV–vis spectroscopic method was quick, relatively cheap and accurate enough to allow the effects of the development of marine fouling on transparent surfaces for use in marine underwater optical applications to be monitored. © 1998 John Wiley & Sons, Ltd.     

Optical probing of surface acoustic waves

Light diffraction by surface acoustic waves is used in studying the propagation characteristics of Rayleigh waves on y-cut z-oriented LiNbO3. In reflection, only the surface deformation contributes to the diffracted light. In transmission, the photoelastic effect, which is incident beam polarization dependent, must also be considered. Such optical probing has been used to study the Fresnel diffraction radiation pattern of an interdigital transducer, to measure beam steering effects related to transducer misalignment on an anisotropic substrate, and to measure reflection and transmission coefficients of an electrically loaded transducer. Attenuation measurements have been made over frequencies as high as 3.5 GHz. The power dependence of attenuation and harmonic generation is also examined.     

基于压缩感知的高速移动环境中OFDM信道估计

针对目前高速移动信道中通信质量较差,为降低高速移动环境中信道估计误差,建立了以Winner Ⅱ信道为基础的高速信道OFDM系统仿真模型,通过压缩感知技术对移动信道进行估计,并与传统的信道估计方法进行比较.仿真结果表明,压缩感知技术能大幅度提高高速移动环境中的OFDM系统信道估计精度.     

超精密抛光自由曲面光学的表面生成

超精密抛光是一种新兴的用于制造高精度、高品质的自由曲面光学加工技术.该技术可突破其他自由曲面加工技术的限制.如飞刀铣削和快刀伺服加工的低效、非铁材料的局限等.然而,对超精密抛光中表面生成机理的理解,目前还不完善.探讨了超精密抛光过程中加工策略对表面生成的影响.进行了一系列抛光实验.研究结果表明:抛光表面的质量很大程度上依赖于加工过程条件及抛光策略的适当选择.抛光加工不仅可用于去除其他加工方式所产生的不利性刀纹,还可以产生功能性应用的结构性表面.该研究结果为深入理解超精密抛光自由曲面光学的表面生成机理,以及优化超精密抛光的表面质量,提供了重要依据和方法.     

高速列车天线及其环境的一体化建模与分析

采用时域有限差分(FDTD)法和完全匹配层(PML)技术对高速列车顶部单极天线及列车车体进行了一体化建模研究,通过数值模拟直接给出了空间入射场与天线输出电压、电流的关系,分析了入射波方向和高速电气化铁路接触网导线对天线输出电压、电流的影响.研究了入射角不同时天线上电流分布的变化情况.结果表明:一体化建模与分析能够直接将空间场参数与天线输入端路参数联系起来,这是传统的电波传播研究方法难以做到的.     

高空高速环境热光学分析及光学窗口设计

为提高高空高速环境下机载光谱相机光学系统的成像性能,分析了飞行高度对光学窗口面型变形的影响,合理设计光学窗口厚度。基于有限元流固耦合、流热耦合模型,仿真高空高速环境下气动压力、气动热载荷对光学窗口的作用,分析了飞行高度对不同厚度光学窗口面型变形的影响;初步选择光学窗口厚度,利用Zernike多项式对该光窗面型变形进行拟合并输入光学软件,以MTF及波相差为评价指标,分析了光学窗口变形对光学系统成像性能的影响,最终确定合理的光学窗口厚度。结果表明:飞行器在5～30 km高空以3 Ma速度、5毅攻角飞行时,口径200 mm的光学窗口合理设计厚度为15 mm。为不同飞行高度范围光学窗口厚度的选择及优化提供了一定依据。     

Multisectional modeling of high-speed electrooptic modulators integrated in a microwave circuit CAD environment

We present a new multisectional model for high-speed electrooptic modulators, fully integrated within the framework of a microwave circuit computer-aided design (CAD) suite (MWOFFICE). Starting from geometrical and layout parameters, the model allows both simple (traveling-wave) and complex (phase reversal, periodically loaded) structures to be assembled, analyzed, and optimized from the standpoint of the electrical and electrooptic response (including chirp effects) both in small-signal (analog) and in large-signal (digital) operation, exploiting standard simulator tools. At no additional effort, parasitic and passive elements (such as optical or electrical delay paths) can be directly included in the modulator schematic, and the effect of transitions and package parasitics can be readily accounted for at a circuit level. Moreover, model integration within a circuit CAD suite enables one to seamlessly perform driver and modulator design and optimization within the same monolithic or hybrid circuit environment. Comparisons with experimental and literature data and design examples are presented to validate the approach and stress its potential in the design of high-speed electrooptic modulators.     

PC-BASED SURFACE RECONSTRUCTION OF MEDICAL CT IMAGES

It is an active research area to reconstruct 3-D object and display its visible surfacesfrom cross-sectional images. In this paper, the methods of reconstructing 3-D object from medicalCT images and displaying the visible surfaces are discussed. A polygon approximation methodthat forms polygon with the same number of segment points and a fast interpolation method forcross-sectional contours are presented at first. Then the voxel set of a human liver is reconstructed.And then the liver voxel set is displayed using depth and gradient shading methods. The softwareis written in C programming language at a microcomputer image processing system with a PC/ATcomputer as the host and a PC-VISION board as the image processing unit. The result of theprocessing is satisfying.