组网雷达检测概率研究

分析了单部雷达对非起伏目标和起伏目标（Swerling Ⅰ～V）的检测概率与检测因子的关系,对多部雷达的检测概率进行融合,研究并比较了组网雷达与单部雷达的检测概率及检测范围.对基于单脉冲雷达和多脉冲积累雷达的检测概率仿真分析表明,在一定的虚警概率下,组网雷达提高了对目标的检测概率,相同的发现概率下的组网探测距离大于单部雷达探测距离.     

雷达组网反隐身可行性仿真分析

通过仿真算法分析出同一目标在不同空间角度的雷达截面（RCS）值以及不同频段探测时的不同RCS值,并通过仿真计算提出雷达组网反隐身的可行性。     

雷达目标特征数据库在雷达组网仿真上的应用

传统雷达组网仿真中,认为目标为点目标,目标的RCS(Radar Cross Section)是一个常数;实际上目标的RCS是随雷达频率、目标相对雷达姿态变化的函数。该文通过对复杂雷达目标进行电磁建模,计算其在各姿态和各频点的RCS数据,把计算结果存储在数据库中建立雷达目标特征数据库。建立了雷达组网仿真系统,系统由主控计算机、雷达目标特征数据库、若干雷达站组成。仿真结果表明:利用雷达目标特征数据库获得雷达在每个时刻观察的RCS比传统的把飞行器RCS当成常数,进行雷达组网仿真,仿真结果更接近实际的情况;通过多个雷达组成雷达网进行数据融合共同探测目标,可以大大提高雷达对目标的检测概率。     

微波超视距雷达组网探测范围研究

本文研究了雷达组网时目标雷达散射截面（radar cross section, RCS）在方位角上的分布对微波超视距雷达探测范围的影响. 首先在蒸发波导条件下,利用抛物方程法推导了电磁波的传播因子,得到了电磁波场强随传播距离和高度的变化规律;然后在此基础上,结合目标RCS在高度和方位角上的分布,研究了目标的回波功率,利用改进的雷达方程得到了微波超视距雷达对目标最大探测距离的计算方法,建立了雷达网探测范围评估模型并进行了仿真. 仿真计算结果表明:在目标运动姿态未知情况下,雷达组网使雷达的探测范围增加了11.20%,在特定方向上使探测距离增加了16.67%;在目标运动姿态已知情况下,雷达组网在部分方位角上增大了最大探测距离,为微波超视距雷达的组网使用提供了理论支撑.     

雷达组网探测巡航导弹能力建模与仿真

建立雷达组网探测巡航导弹能力的评估模型是雷达组网作战效能评估的一个重要内容。本文在模拟巡航导弹飞行航迹的基础上,通过网内雷达与目标间的坐标转换,推导了网内各雷达对巡航导弹雷达散射截面积（RCS）观测值随着时间变化的起伏模型,再依据雷达组网点迹融合探测性能模型,仿真分析了雷达组网对巡航导弹的探测能力。结果表明该方法能够比较准确地计算雷达组网对巡航导弹的发现概率,为雷达组网系统的作战效能评估提供了一定的依据。     

反隐身飞机突防战术仿真

为研究体系作战条件下地基雷达组网和预警机结合探测隐身飞机能力,基于隐身飞机三维建模并计算雷达散射截面积(Radar Cross Section, RCS),分析了隐身飞机突防过程中不同时刻雷达探测性能变化情况。首先,采用专业软件建立了某型隐身飞机三角面元模型,采用物理光学法(Physical Optics, PO)计算了飞机RCS。其次,建立了雷达坐标系与飞机机身坐标系转换关系,计算了不同时刻机身坐标系中雷达照射角度。最后,通过构建隐身飞机突防模型,研究不同时刻地基雷达组网和预警机联合探测隐身飞机的雷达探测距离和探测概率变化情况。仿真结果表明,地基雷达组网和预警机能够有效利用隐身飞机侧向、后方和上方RCS较大(10～20 dB)的特点,其中,预警机最大探测距离达151 km,平均探测距离在80 km左右,地基雷达组网的平均距离探测为50 km左右,对隐身飞机具有良好探测能力。     

一种组网雷达波束资源优化分配模型

针对空面目标组网雷达协同调度的资源优化分配问题,通过分析不同目标的重要性、RCS和跟踪质量对调度资源的差异化需求,以组网系统探测效益为优化目标,构造了一种基于波位调度的动态规划模型。利用改进的拍卖算法对该模型求解各雷达最优的波位分配,在满足不同类型目标对跟踪资源需求的同时,降低了组网系统总体波束资源的消耗。该方法解决了多雷达目标调度中资源分配和冲突消解的协同问题,降低了计算量,提高了时间和能量两种资源的合理分配和有效利用率,实现了组网系统高效的波束资源管理。通过仿真验证,证明了所提模型的正确性和算法的有效性。     

基于仿真计算的飞行器雷达隐身性能评估

从飞行器雷达散射截面的计算机仿真出发,对运动飞行器的RCS动态特性和复杂电磁环境下的隐身性能进行研究.基于运动目标姿态参数的转换原理,得到运动目标的动态RCS特性,通过相对计算方法计算雷达的瞬时探测概率,并给出有源和无源干扰条件下探测概率的计算方法;以单部雷达的目标检测准则为基础,给出了雷达组网模式下的综合检测准则;考...     

雷达组网协同探测试验航次数量设计改进

雷达组网协同探测试验是在实际的外场环境下,利用实装飞机作为目标,测试两部同型雷达对目标协同探测的稳定跟踪距离。通过对传统航次数计算方法进行分析,发现其将距离取样间隔内检测概率的变化视为线性变化,当距离取样间隔增加时,数据评估的检测概率与实际雷达检测概率间出现明显误差,使得统计结果的可靠性下降,提出一种试验航次数量改进算法,该方法能够实时计算检测概率误差并进行修正,选择最佳距离取样间隔,在确保样本量的前提下获得合理的航次数量,节约了试验成本。     

多频外辐射源雷达无人机探测实验研究

外辐射源雷达作为一种新兴的无人机监视手段近年来得到了广泛关注。常规的单频外辐射源雷达容易受无人机飞行姿态、观测角度等因素影响,在探测稳定性和跟踪连续性上表现不足。多频探测对缓解目标RCS起伏,提高雷达探测性能具有重要的意义,是外辐射源雷达的发展方向之一。本文从目标散射特性的角度论述了多频探测的重要性,首先分析并仿真了照射源频率对无人机RCS的影响,然后提出了针对数字电视外辐射源雷达无人机探测的多频检测方法。仿真与实测结果表明,使用不同频率照射源探测时无人机的RCS和信噪比有明显差异,多频联合处理能使目标信噪比更加平稳。研究成果为外辐射源雷达向多频融合发展提供了参考依据。     

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.     

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.     

Technology innovation and process integrations for sub-100nm gate patterning

This paper presents a brief overview of the Applied Centura(R)DPS(R)system,configured with silicon etch DPS Ⅱ chamber, with emphasis on discussing tuning capability for CD uniformity control. It also presents the studies of etch process chemistry and film integration impact for an overall successful gate patterning development. Discussions will focus on resolutions to key issues, such as CD uniformity, line-edge roughness, and multilayer film etching integration.     

White organic light-emitting devices based on fac tris（2- phenylpyridine） iridium sensitized 5,6,11,12-tetraphenylnap -hthacene

We have fabricated the white organic light-emitting devices （WOLEDs） based on 4,4＇ -bis（2,2 -diphenyl vinyl）-1,1＇ - biphenyl （DPVBi） and phosphorescence sensitized 5,6,11,12,-tetraphenylnaphthacene （rubrene）. The device structure is ITO/2T-NATA （20 nm）/NPBX （20 nm）/CBP： x%Ir（ppy）3：0.5% rubrene （8 nm）/NPBX （5 nm）/DPVBi （30 nm）/Alq（30 nm）/LiF（0.5 nm）/A1. In the devices, DPVBi acts as a blue light-emitting layer, the rubrene is sensitized by a phosphorescent material, fac tris （2-phenylpyridine） iridium [Ir（ppy）3], acts as a yellow light-emitting layer, and N,N＇ -bis- （1-naphthyl）- N,N＇ -diphenyl -1, 1＇ -biphenyl-4,4＇ -diamine （NPBX） acts as a hole transporting and exciton blocker layer, respectively. When the concentration of Ir （PPY）3 is 6wt%, the maximum luminance is 24960 cd/m^2 at an applied voltage of 15 V, and the maximum luminous efficiency is 5.17 cd/A at an applied voltage of 8 V.     

Complete approach to automatic identification and subpixel center location for ellipse feature

To meet the need of automatic image features extraction with high precision in visual inspection, a complete approach to automatic identification and sub-pixel center location for similar-ellipse feature is proposed. In the method, the feature area is identified automatically based on the edge attribute, and the sub-pixel center location is accomplished with the leastsquare algorithm. It shows that the method is valid, practical, and has high precision by experiment. Meanwhile this method can meet the need of instrumentation of visual inspection because of easy realization and without man-machine interaction.     

小角度扩展相关性近似算法分析

本论文提出一种在多天线MIMO信道相关性建模中小角度扩展近似理论算法,并应用于分析MIMO系统性能。分析中分别对三种不同角能量分布情况下的空间相关性研发快速近似计算法,并同时提出双模(Bi-Modal)角能量分布情况下的近似运算。通过分析这些新方法的近似效率,可以得到计算简单、复杂度低、而且符合实际的MIMO相关信道矩阵,对系统级的快速高效计算法的研究和系统级的评估以及误差分析具有重要的意义。     

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.