雷达辐射源信号识别结果评估方法研究

针对雷达辐射源信号识别结果评价方法杂乱,指标单一等问题,提出一种新的信号识别结果评估体系结构,将识别率测试结果引入到雷达辐射源信号识别结果评估中,构建了基于识别率测试结果的雷达辐射源信号识别结果评估指标体系,建立了评估指标的层次结构模型,应用模糊综合评价法对识别结果进行评估,并对三种识别方法进行了计算机仿真评估实验,验证了新方法的可行性.     

基于脉冲样本图的雷达辐射源识别方法

雷达辐射源识别是雷达对抗侦察信号处理的关键环节。由于现代雷达体制日益复杂,传统的辐射源识别方法面临着越来越严峻的问题。因此针对这种情况,提出了一种基于脉冲样本图雷达辐射源识别算法。这种算法无需对相互叠加的雷达辐射源信号进行完全分选,并且不需要进行传统识别方法中的特征提取过程,简化了处理环节。在脉冲流密度适中的情况下,该算法具有很好的判别准确率。仿真结果验证了该方法的可行性和实用性。     

基于DAGSVM的雷达辐射源信号分选与识别

支持向量机具有较好的解决小样本、非线性问题的能力,而DAG算法具有分类精度高的优点。针对现有方法分选与识别准确率不高和对参数变换敏感的问题,在DAGSVM的基础上,提出一种新的雷达辐射源分选与识别方法。首先概述了支持向量机的原理及特点,然后完成了对SVM多分类器的设计,介绍了DAG算法,提出了基于DAGSVM的雷达辐射源信号分选与识别。并通过仿真实验分析了分类器对分选识别结果的影响。实验结果表明,使用DAGSVM这种方法是可行的,该方法具有较强的泛化性能,明显地提高了信号分选识别的准确性。     

雷达信号识别效果的模糊综合评价研究

雷达辐射源识别是电子对抗情报系统中的关键技术之一,对其识别效果进行科学的评估是一项全新的课题。以往大多数学者评价雷达信号识别方法的好坏主要是比较识别率的高低。针对雷达辐射源识别效果评估指标单一等缺点,选取识别时间、识别率测试结果的均值和方差作为评估指标,将模糊综合评价法引入雷达辐射源识别效果的评估,提出基于模糊综合评价的雷达信号识别效果评估方法,并通过计算机仿真,对三种识别方法进行了评估实验,验证了该方法的可行性。     

基于径向基概率神经网络的雷达辐射源信号识别

雷达辐射源信号识别是电子情报系统和电子支援系统的重要组成部分。文章提出一种基于径向基概率神经网络的雷达辐射源信号识别方法，通过对几种典型雷达辐射源信号复杂度特征提取和采用径向基概率神经网络分类器进行分类识别的实验结果表明，文章所提出的方法是有效的，能在较宽的信噪比范围内获得满意的识别率。     

基于最近邻方法的雷达辐射源信号识别研究

在分析最近邻方法理论的基础上,提出了一种新的雷达辐射源信号识别结构,引入了一种新的距离贴近度度量方式。建立了基于最近邻方法的雷达辐射源信号识别模型,并分别在大样本和小样本数据集合对不同噪声背景下的雷达辐射源正确识别率和识别时间进行了比较分析。仿真表明,基于最近邻的雷达辐射源信号识别方法简单易行,快速简洁,有较高的正确识别率。     

数据库样本缺失下的雷达辐射源识别

目前,基于机器学习的雷达辐射源识别技术大多以训练集和测试集同分布为假设,当雷达数据库样本不足导致与信号真实分布存在偏差时,传统的分类方法效果不佳.为此,将迁移学习理论引入识别系统,设计了一种基于结构发现与再平衡的雷达辐射源信号识别方法.通过对数据库和待识别辐射源信号样本进行聚类分析发现数据结构信息,通过重采样处理修正其分布差异.将新采样数据输入支持向量机进行训练并对侦收样本进行识别.仿真实验表明,在新训练样本集上学习的模型对测试集的分类性能有了很大的提升.     

一种基于脉冲样本图和模糊理论的雷达辐射源识别

在现代信号密集环境中,传统的雷达信号特征描述方式很难对复杂体制雷达辐射源进行描述和识别.因此提出了一种基于脉冲样本图和模糊理论的雷达辐射源识别算法,运用格贴近度的模糊识别算法进行雷达辐射源识别.该方法省略了特征提取过程,简化了处理环节,仿真结果表明,这种方法具有很高的识别准确率.     

基于KNN和雷达辐射源脉间参数的舰船目标个体识别方法

针对同型多目标位置接近无法有效区分的问题,提出了一种基于KNN和雷达辐射源脉间参数的舰船目标个体识别方法.根据雷达辐射源脉间参数计算待识别雷达信号与已识别雷达信号的参数关联度,若关联度小于阈值则认为是不同雷达,否则认为是同型雷达则利用最近邻分类算法通过计算待识别雷达目标位置点与已识别雷达目标历史航迹点的距离来判决待识别...     

基于距离度量方法的雷达辐射源信号识别研究

为了能够在多种距离度量方法中选择一种最优的算法,提高基于距离度量方法的雷达辐射源信号识别的正确识别率,构建了雷达辐射源信号识别模型.并在不同的噪声背景下对基于距离度量方法的雷达辐射源识别模型的正确识别率和识别时间做了比较,最后进行了大量的仿真实验,给出了识别结论.     

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.     

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.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

中国建立EB级存储实验室,致力云计算应用(英文)

正With the support of 863 programs,Sugon Information Industry Co.,Ltd.,set up a dawning EB-class storage laboratory to address massive data storage requirements and largescale cloud computing demonstration applications.The Dawning EB-class cloud storage system adopts advanced fault-tolerant architecture,efficient data fault-tolerant algorithms with user authentication and data encryption policies to deal with the"lost""wrong"and"stolen"problems of data for ensuring the reliability and safety of the EB-class storage system in the public network application environments.The Dawning EB-class Storage Laboratory taking advan-