基于最大选择恒虚警的脉冲探测方法

最大选择恒虚警（GO-CFAR）处理技术是雷达信号检测的一种重要方法。在最大选择恒虚警算法的基础上提出了一种应用于战术空中导航（TACAN）系统脉冲信号的探测方法,通过Simulink仿真对该方法进行了验证。     

基于单片FPGA的雷达动目标检测系统

介绍了一种基于单片现场可编程门阵列（FPGA）的雷达动目标检测系统,阐述了恒虚警处理和FPGA技术,对输入数据的存取方式、多普勒滤波器组和恒虚警处理的实现进行了详细论述。     

基于异常单元删除的改进CFAR检测器

雷达在大入射余角海杂波下进行检测时易受到功率突然增大的杂波异常单元影响,虚警率及误检率较高。为解决此问题,提出具有杂波抑制模块与恒虚警模块的二级检测器。杂波抑制模块通过参考单元的协方差矩阵构造正定矩阵,求解其矩阵范数用以估计杂波功率水平,根据功率水平设置一个动态门限,剔除异常单元后的杂波作为待检测信号输入恒虚警模块,恒虚警模块使用基于有序数据可变性的自动删除平均（ACCA-ODV-）CFAR检测器来改进传统变化指数恒虚警（VI-CFAR）检测器。仿真结果表明,新检测器在均匀杂波环境中检测性能与单元平均恒虚警(CA-CFAR)检测器几乎相同,在多目标环境中检测性能远远优于最大选择恒虚警(GO-CFAR)检测器、最小选择恒虚警(SO-CFAR)检测器、CA-CFAR检测器及VI-CFAR检测器,在杂波边缘环境中虚警控制能力仅次于VI-CFAR检测器与GO-CFAR检测器。综合考虑实测数据中各个检测器的检测结果,改进后的检测器在高分辨率大入射余角情况下具有最优的检测性能。     

雷达杂波环境恒虚警率处理的实现

恒虚警率检测器是雷达信号处理机中的重要组成部分.对雷达自动检测和恒虚警率处理方法进行了综述,讨论了瑞利分布杂波背景中雷达目标恒虚警检测的原理,阐述了实现杂波背景中雷达目标恒虚警检测的方法.     

一种基于GO-CFAR的塔康信号检测技术

在最大选择恒虚警率（GO-CFAR）雷达信号检测方法的基础上提出了一种应用于塔康（TACAN）信号的检测技术,它采用前后滑窗单元平均产生噪声估计,再对二者进行比较取最大值实现对目标信号的检测,从而代替了传统塔康检测中的固定门限设置。在均匀高斯白噪声背景下,得出了塔康信号的检测概率、虚警概率和平均判决阈值的解析表达式。使用SIMULINK建立了系统仿真模型,对该方法进行了验证。分析结果表明,该技术具备较好的塔康信号检测性能。     

多目标环境下的恒虚警率处理器

本文提出一种新型二侧单元平均选大恒虚警率处理器(NEWGO-CFAR)。NEWGO-CFAR处理器不仅能够在“杂波边缘”雷达环境中取得比GO-CFAR处理器更加完美的结果,更重要的是它能够实现多目标检测,而且其处理对时间比能够进行多目标检测的OS-CFAR处理器的处理时间要短得多,进而使得多目标检测向实时处理迈进一大步。本文通过计算仿真展示了这一新型处理器的性能。     

雷达信号处理技术及仿真

在此借助Matlab软件对雷达信号处理过程进行仿真,从仿真图形直观地理解雷达信号处理过程,也体现了Matlab软件在雷达信号处理仿真中的方便、快捷等优点。另外,对当今雷达恒虚警检测技术的现状、不足及其发展动态进行了论述,并通过改进模拟退火算法,提出了一种最优门限恒虚警检测算法。该算法能够在恒虚警检测过程中有效地选取检测门限,提高了雷达系统的恒虚警检测性能,对恒虚警发展具有一定的参考价值。     

一种基于FPGA的慢门限恒虚警处理电路设计

雷达信号的检测多是在干扰背景下进行,如何从干扰中提取目标信号,不仅要求有一定的信噪比,而且必需有恒虚警处理设备。恒虚警处理是雷达信号处理的重要组成部分,慢门限恒虚警处理主要是针对接收机热噪声,文中介绍一种基于FPGA嵌入式设计的慢门限恒虚警处理电路,给出了仿真模型及仿真结果,并已将其用于某检测器中,取得了良好的经济效益。     

一种改善恒虚警处理性能的方法

本文介绍了两侧单元平均选大恒虚警(GO-CFAR)处理的工作原理，重点分析了警戒单元对恒虚警处理性能的影响，并给出了仿真结果，证明了适当选取警戒单元会大大改善系统的检测性能。     

基于FPGA的激光雷达恒虚警率控制技术研究

研究了激光雷达中的雪崩光电二极管恒虚警率控制技术,提出了一种基于FPGA的恒虚警率控制电路,通过噪声检测能够有效地根据背景辐射进行自适应调整,保持恒定的虚警率,并使雪崩二极管处于最佳工作偏压.实验结果表明其良好地实现了恒虚警率控制.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.