基于轨迹线性化方法的飞艇姿态控制研究

平流层飞艇在靠浮力升空的过程中,需要对其进行姿态稳定控制.针对飞艇的姿态控制系统的非线性、不确定性和多输入多输出特性,给出了基于轨迹线性化的飞艇姿态控制方法.根据奇异摄动理论,将飞艇姿态系统分成内、外两个回路,依据轨迹线性化方法(TLC)分别设计了内回路控制器和外回路控制器;最后,对所设计的飞艇姿态稳定控制器进行了数字仿真验证.仿真结果表明:即使在控制系统参数存在不确定性的条件下,仍可在所设计的闭环系统中实现飞艇姿态的稳定控制.     

滑模变结构控制在平流层飞艇姿态控制中的应用

为了较好地控制平流层飞艇的姿态,将滑模变结构控制方法和PID控制方法应用于平流层飞艇的姿态控制设计中,该飞艇模型具有参数静不稳定性。首先,以平流层飞艇平台为研究对象,建立了飞艇的六自由度线性动力学方程。然后,结合滑模变结构控制律和经典控制方法,设计了飞艇姿态控制的滑模控制器和PID控制器。最后,通过数据仿真,得出了较好的姿态控制效果,并对两种控制方法进行了对比分析。仿真结果表明,滑模变结构控制可以作为平流层飞艇平台姿态控制的研究方法,能够较好地控制飞艇的姿态。     

平流层飞艇特征结构配置增稳设计

对飞艇非线性六自由度模型进行线性化,得到了飞艇的状态方程,并将其分为纵向和侧向两组.以飞艇非线性模型为基础对飞艇自然特性进行了分析,对飞艇的纵向运动及侧向运动的稳定性进行了分析仿真.运用基于线性矩阵不等式（LMI）的特征结构配置方法对平流层飞艇进行增稳控制律设计,不仅实现了特征值的配置,同时确定闭环系统特征值对应的特征向量和广义特征向量.     

平流层飞艇激光风速仪的设计和分析

准确的风场数据对于平流层飞艇实现长时间驻空任务有着重要的安全保障作用。针对20 km高度处空气稀薄的特点，为实现平流层飞艇航行环境的风场探测需求，设计了波长为532 nm的直接探测多普勒光纤激光风速仪。使用双通道法布里-珀罗标准具为鉴频器和波长可调谐的脉冲光纤激光器，完成了系统的结构设计。系统参考了相干测风激光雷达的光路设计，采用收发合置的望远镜设计方案，无探测盲区，接收视场角较小，提高了全天探测的性能。利用液晶相位延迟器的光束偏振特性可实现光路探测方向的控制。以最小的风速探测误差为标准，通过仿真分析选取了法布里-珀罗标准具的各项参数，并对系统的风场探测性能进行了分析。仿真过程中，激光器的平均功率为500 mW，积分时间为10 s，距离分辨率为100 m，分析结果表明，风速误差在500 m探测距离内小于1 m/s，计算得出的风向误差在风速大于10 m/s的情况下，其风向精度优于5°。     

平流层飞艇晃动对艇载雷达回波影响的分析

平流层飞艇载雷达系统较之地基雷达针对临近空间目标更具探测优势,但也存雷达探测性能受飞艇运动影响的问题,须结合飞艇的运动特点分析艇载雷达的回波形式。对此,本文从艇载雷达天线阵元的速度差别入手,分别建立了艇载雷达天线阵元的运动计算模型和艇载雷达回波计算模型。根据建立的模型,分析了飞艇晃动对雷达信号的影响,计算了不同因素对天线阵元速度的影响,并分别在天线阵元速度差别最大和最小的情形下进行了回波仿真,结果显示:在飞艇运动状态下,艇载雷达探测效果随目标距离增加而下降,但在不同的探测方向上下降程度是不同的。      

一种平流层飞艇高度控制方法

现代平流层飞艇要求飞艇能够安全、平稳地抵达平流层目标高度。首先分析了平流层飞艇高度控制与压差控制的关系, 然后针对平流层飞艇的特点提出了一种前馈式高度控制的方法。仿真结果表明,前馈式高度控制器具有一定的局限性, 不能同时满足高度和压差的控制目标。为此,提出了压差控制器以及两种解决高度控制器与压差控制器融合问题的方案, 最后的仿真结果表明, 限制高度控制权限的方案能保证飞艇安全平稳地到达目标高度。     

关于高空飞艇抗热能力的研究

高空飞艇在平流层高度昼夜工作过程中,作为浮升气体的艇体内氦气受太阳能辐射以及艇外低温环境的影响,其平均温度变化范围较大。艇体内氦气平均温度的变化将导致飞艇艇体内外压差的变化,而艇体内外压差的变化是高空飞艇总体设计阶段对囊体材料选取时必须考虑的重要设计依据之一。通过高空飞艇抗热能力仿真计算与分析,指出高空飞艇的抗热能力必须在提高囊体强度的前提下才可以得到根本的提升,而加大副气囊体积对抗热能力影响不大反而将导致飞艇重量的增加。     

基于多普勒激光雷达低空风切变的数值仿真

多普勒激光雷达是目前在晴空条件下对低空风切变最有效的一种探测手段。完成了基于多普勒激光雷达探测所需的微下击暴流、侧风切变和低空急流等三维变化风场的数值仿真,仿真结果得到了各种风场的基本特征。依据多普勒激光雷达的波束扫描方式,选取雷达扫描仰角为5°,扫描半径为8 km,雷达径向步长为100 m来扫描仿真风场,最后得到雷达探测变化风场的仿真径向数据。这对于深入理解风切变的产生机理以及实现由激光雷达对风切变的探测、识别和预报等后续研究具有重要意义。仿真过程建立的变化风场模型简单,模型参数变化灵活、方便实用。     

基于自适应反演滑模的四旋翼无人机抗风研究

针对四旋翼无人机易受风扰,影响控制精度的问题,提出了一种自适应反演滑模轨迹跟踪控制策略,基于NewtonEuler建立在紊流风场下的四旋翼无人机动力学模型,将控制系统分成姿态子系统■和位置子系统(x,y,z),引入过渡控制律,实现欠驱动耦合控制,解算出理想姿态,滑模控制抑制风场对四旋翼无人机的影响,反演控制来设计镇定控制项,利用Lyapunov理论证明了闭环系统的稳定性,通过MATLAB仿真,仿真结果表明所设计的控制器收敛速度快,响应时间较短,鲁棒性强。     

机载测风激光雷达下视VAD反演及算法仿真

为了研究机载测风激光雷达对机下空域3维风场分布进行探测的问题,基于陆基测风激光雷达建立风场模型,采用Levenber-Marquardt(LM)最小二乘法优化径向速率,与传统反演算法进行了仿真对比.结果表明,机载测风激光雷达的工作原理和扫描方式与陆基测风激光雷达类似,不同的是,机载测风激光雷达不仅受飞机速度干扰,而且存在飞机飞行状态不稳定性影响、地球曲率影响、地面强散射回波干扰、地面杂波干扰等特有误差来源,使得风场反演难度更大;而LM最小二乘法具有Newton-Gaussian最小二乘法的快速收敛特性和梯度下降法的保证收敛特性,能满足风场快速和准确的反演.相关结果对测风激光雷达的优化具有参考价值.     

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.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

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.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.