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频率预测是保障短波通信的关键技术。针对现有短波频率预测方法中数据处理过程复杂、输入参数条件苛刻、工程实现难度较大等问题,提出了一种基于泛克里格(Universal Kriging)空间重构法的海上短波通信频率预测方法。利用海军频率管理系统中大量的实用通信频率数据,基于球状模型、指数模型、高斯模型三种典型变异函数理论模型,研究了通信频率的空间相关性,建立了反映沿纬度方向通信频率变化剧烈程度的漂移表达式,通过交叉重构法对海上短波通信频率进行预测。实验结果表明,泛克里格法在海上短波通信频率预测中具有良好的适用性和可靠性,对未知海域短波通信频率的预测优选具有重要意义。 相似文献
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如何有效实现短波通信频率的优选,是推动短波通信技术发展和应用的关键。针对这一核心问题,分析介绍了一种新的频率优选方法——短波通信自优化技术,并阐述了其提出背景和技术特点。在系统梳理频率优选方法分类的基础上,对各类方法的优缺点、适用范围、相互关系进行分析讨论。对短波通信频率自优化技术发展中涉及的数据要素选取、频率数据重构等关键技术进行初步分析讨论,明确了频率自优化技术的地位和作用。 相似文献
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提出了一种基于多体制探测数据融合的最高可用频率(maximum usable frequency,MUF)预报方法.该方法基于数据融合的思想,将电离层垂测数据和斜向探测数据进行融合处理,对短波通信最大可用频率进行预报,试验结果表明,该方法能够有效提升对MUF预报的准确性,预报相对误差降低19.23%,绝对误差降低0.33 MHz;对比实验结果,春秋季和冬季的预报精度提升尤为明显,平均达到25%以上,夏季能达到10%以上.该方法易于工程实现,能够对短波通信选频、短波广播覆盖分析等提供准确的数据支撑. 相似文献
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为便于海上短波通信频率数据的有效管理和使用,实现短波通信频率的优选,设计了基于电子海图的短波频率辅助决策系统。系统以电子海图显示技术为支撑,短波频率数据为核心,结合短波频率预报理论研究成果实现短波频率数据管理、短波选频辅助决策。将短波频率数据与电子海图相融合实现短波频率数据可视化以及与实际海域相结合的联合分析,系统的构建对于实现频率的优选具有实际参考价值。 相似文献
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机载短波通信是CNI(通信/导航/识别)体系内不可或缺的组成部分。运用短波通信理论分析了机载短波通信通信频率与通信距离之间的关系,鉴于通信距离在实战中的的重要性,提出了一种预测短波通信频率的方法。方法主要为以下2点:一、特定时间和路程下的最高可用频率;二、每一频率在每一时段的信噪比及可用性百分比。方法主要经由理论分析、软件辅助计算,并结合电磁环境的监测结果和实际地面互联互通经验对预测结果进行修正,给出每一时刻的最佳通信频率。最后,通过真实飞行试验对该方法的可行性进行了工程验证。 相似文献
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GU Min-fen LIANG Zhong-cheng WANG Ren-zhou DONG Xiang-mei ZHANG Pei-ming CHEN Jia-bi 《光电子快报》2008,4(2):150-152
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. 相似文献
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R.Pelzer P.Lindner T.Glinsner B.Vratzov C.Gourgon S.Landis P Kettner C.Schaefer 《半导体技术》2004,29(7):86-91
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… 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献
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Michael Reilly 《半导体技术》2004,29(12)
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. 相似文献
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Thomas M.Trexler 《半导体技术》2004,29(5)
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. 相似文献