直升机起降中无线紫外光喷泉码引导方法研究

为了提高直升机在应急无线紫外光通信辅助起降中信标搜寻、定位降落的效率和可靠性,该文提出一种基于喷泉(LT)码的分等级编码通信方案,采用不同等级编码的分级方法设计了不同场景、不同引导阶段的通信策略,分析了高丢包率信道环境中变化删除概率下的误比特率,并与其他传统信道编码进行了比较。实验仿真结果表明,在二进制删除信道下,该分等级编码方法可显著降低LT码的误比特率,提高了编译码性能;该通信策略适用于高丢包率信道环境,能获得更好的通信效果,提高了直升机应急辅助起降的安全性。     

无线紫外光MIMO直升机助降ALOS链路性能分析

无线紫外光通信具有高速率高可靠性的特点,可以满足复杂环境下的通信。通过直升机助降的过程提出近似直视通信方式,并研究了无线紫外光MIMO系统的ALOS通信链路模型,同时计算了弱湍流条件下ALOS链路中MIMO系统的误码性能,并仿真分析其信噪比、发射功率、发射（接收仰角）以及通信距离对误码率的影响。计算分析当发射（接收）仰角小于35时,误码率随着发射（接收）仰角的增大,其增长趋势比较明显,当大于35时,误码率随着发射（接收）仰角的增大,其增长趋势变缓。结果表明,在无线紫外光ALOS链路中,采用天线阵列和多探测器的MIMO技术能够较好地降低误码率和抑制大气湍流,并提高抗衰弱能力。     

无线紫外光非直视通信信道容量估算与分析

无线紫外光非直视通信中,大气散射和收发角度是影响紫外光通信系统性能的重要因素。在无线紫外光非直视通信单次散射模型的基础上,提出了一种适合于紫外光非直视通信的信噪比和信道容量估算方法,并将该方法与量子极限法进行对比计算,验证了无线紫外光通信信道容量估算法的正确性。利用计算机仿真了收发端角度对紫外光通信中路径损耗、信道容量的影响,并分析了不同背景噪声环境下的信道容量。仿真结果表明,发送、接收仰角及接收视场角对紫外光通信中的路径损耗、信道容量影响较大,而发散角对其影响不大,且信道容量随背景噪声的增大而减小。     

基于单LED的无线紫外光通信系统设计与实现

介绍了紫外光通信特点和信道模型,以LED为光源、光电倍增管为光接收器设计无线紫外光数字通信系统方案,研制了无线紫外光通信设备样机,在不同条件下进行实验.实验结果表明,在夜晚,晴天,近距离,校准条件下的通信效果优于白天,下雨,远距离,未校准的条件下的通信效果,验证了无线紫外光通信的可行性.     

直升机助降中紫外光近直视通信分集接收技术

为了有效抑制直升机降落过程中尾流造成的强湍流效应，采用分集接收技术来进行抑制。根据无线紫外光斜程通信和近直视通信的特性，给出接收信号强度的边缘分布概率密度函数，建立了基于gamma-gamma分布的紫外光近直视通信系统修正模型，将分集接收技术引入该模型。理论分析了湍流效应对接收光信号强度边缘概率密度分布的影响以及最大比合并（MRC）、等增益合并（EGC）和选择性合并（SC）的误码性能。结果表明，大气湍流强度越强，紫外光近直视通信系统的误比特率性能越差；二分集时，MRC，EGC，SC 3种合并方式信噪比性能分别提升了22dB，18dB，16dB。分集接收技术能有效抑制直升机助降过程中的强湍流效应，提升通信系统的稳定性和抗衰落性能。     

无线紫外光Mesh网络技术研究

具有低背景噪声和散射传播特点的无线日盲紫外光通信技术成为人们关注的热点,利用无线Mesh网络技术能充分发挥日盲紫外光通信的优势。本文介绍了日盲紫外光通信的特点,分析了无线Hesh网络采用定向天线的优势和带来的问题,研究了无线紫外光Mesh网络的关键技术,包括定向转发结构模型、单向链路的产生、定向路由技术和可靠性路由技术等。     

无线紫外光协作蜂群无人机集结算法研究

针对存在电磁干扰的复杂多变环境下,蜂群无人机机间通信与位置信息交互受到较大干扰,导致无人机之间形成编队速率和效率降低.提出以"日盲"紫外光(200 nm～280 nm)作为通信媒介,利用其全天候、可非视距、抗干扰能力强等优点设计紫外光信标结构,同时提出一种利用无线紫外光在蜂群无人机机间进行通信定位的方法提升电磁干扰环境下蜂群无人机的通信定位能力;通过建立飞行引导误差模型,改进领航者-跟随者算法在蜂群无人机集结过程中误差反馈大的问题.最终对比理想情形下仿真结果,验证了改进的算法在实际情形下,通过较小幅度的调整可以迅速完成集结.     

大气湍流中直升机助降紫外光引导调制研究

为了研究大气湍流中不同调制方式对无线紫外光通信系统的性能影响,基于紫外光非直视通信模型,理论推导了弱湍流条件下开关键控、脉冲位置调制的误比特率。采用紫外光引导直升机助降模型,在不同调制方式下仿真分析了发射功率、通信距离、发散角、接收视场角、收发仰角对误比特率的影响。结果表明,不同调制方式的误比特率随着发射功率、发散角、接收视场角的增大而不断减小,随着通信距离、收发仰角的增大而增大; 在相同条件下,脉冲位置调制比开关键控的误比特率更低,而且随着调制阶数的增加,误比特率会越来越小。这一结果对提高紫外光通信系统在大气湍流中的抗干扰能力具有一定的应用价值。     

无线紫外光MIMO通信系统信道容量估算方法

无线紫外光通信系统易受大气散射等因素的影响,导致通信信道容量估算准确率较低。为此,提出一种无线紫外光多入多出(Multiple-Input Multiple-Output, MIMO)通信系统信道容量估算方法。根据信道特征,构建无线紫外光MIMO通信系统的信道容量估计模型,获取无线紫外光的单次散射传输特性,利用符号补码式的方法改进空时编码,设定高级检测器中符号的接收能耗,使每个符号保持在标准功率数值范围内,完成通信系统信道检测式编码。根据不同发射角和接收角计算无线紫外光通信的路径损耗比,通过泊松随机分布获得最终通信系统信道容量的估算结果。实验结果表明,所提方法的传输速率可高达8 Mbps,误码率始终低于10^-3 bit/s,估算准确率在90%以上,估计时间低于4 ms,估算效果好,可为通信行业发展提供理论依据。     

紫外光通信及其军事应用前景

紫外光通信是一种新兴的无线光通信技术,可作为常规通信手段的一种补充,其中主要器件的研制和核心技术研究是紫外光通信发展的主要推动力。文章介绍了紫外光大气传输散射特性,紫外光通信的核心器件、技术及发展方向。根据紫外光通信的特点,着重阐述了紫外光通信的应用场合以及在未来战场中具有重要的军事意义。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

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.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

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.