毫米波辐射计在探测空中涂层隐身目标中的应用研究

介绍了毫米波辐射计探测空中涂层隐身目标的机理,对涂层隐身目标和光洁金属目标的天线温度对比度进行了对比计算,并利用毫米波辐射计对空中涂层隐身目标和光洁金属目标进行了探测实验.计算和实验表明,隐身目标引起的天线温度对比度比同等大小的光洁金属目标引起的天线温度对比度大;对毫米波辐射计探测空中目标而言,目标的隐身涂层起不到隐身功能.     

星载红外探测对比度的计算与分析

推导了星载红外探测在地面、大气双背景下探测器处的辐射照度对比度计算公式,计算了目标在不同温度、不同高度的目标与背景的绝对对比度和相对对比度。分析指出:随着目标温度、高度增加,在波长大于2.5 m 区域绝对对比度与相对对比度相应增大,目标高度越高,同等距离下对比度随目标高度的变化越小;波长小于2.5 m 需考虑太阳的影响;当目标在0 km 高度时,2.9~4.1 m 波段为最佳探测波段,随着目标高度的增加,可用探测波段范围增大,峰值波长向短波方向微移,当目标高度大于10 km 时,相对对比度峰值在2.6~2.8 m 之间;距离地面越近,大气对红外辐射的衰减越大。     

3mm与8mm波段无源探测特性的比较

研究了毫米波无源探测器探测草地背景中水泥路面的原理.根据8mm和3mm波段下天线和地物辐射计的特性,计算出8mm和3mm辐射计探测地面目标的天线温度对比度,得到这两种辐射计在各种天线口径和工作条件下的最大探测距离,并对两者的实际探测效果进行了比较.     

基于微波高光谱技术的数据仿真及参数反演研究

发展高光谱微波辐射计对于提升大气参数反演精度具有重要意义。利用微波辐射传输模型mpm93以及BP 神经网络方法分别构建正演上行辐射亮温和反演大气温度廓线的模型,并研究了晴空条件下高光谱微波辐射计反演大气温度廓线的精度。54～58 GHz、64～68 GHz 在氧气吸收波段选取80 个通道作为高光谱通道,基于2015 年5～12 月昆明的探空资料进行正、反演仿真实验。选取微波成像仪/ 探测仪(SSMIS)的9 个温度探测通道进行对比实验,评估分析反演效果。实验结果表明:在大气3～10 km 高度范围内,高光谱通道的反演精度较SSMIS 提高了0.3 ～0.6 K;在0～3 km 高度范围内,反演精度提高了1 K。     

亚毫米波被动探测目标辐射方程与特性研究

目前亚毫米波系统正处于开拓和发展时期,在军事与民用中均具有重要应用.文中主要研究了目标物质的亚毫米波辐射传递方式,并给出目标物质的亚毫米波辐射传递方程新的求解方法.分析了天气现象影响亚毫米波辐射计的探测距离,以云(雾)衰减为例,对探测距离和温度,以及含水量的关系进行了分析.     

探测天顶角与太阳天顶角对卫星红外探测的影响

为了分析不同探测环境对卫星红外探测的影响,推导了倾斜探测路径下目标与背景在探测器入瞳处的辐照度对比度计算公式。计算了目标在海天背景下不同温度、不同高度、不同太阳天顶角、不同探测天顶角条件下,目标与背景在0.75~14μm波段的红外单色辐射照度对比度。分析指出:太阳天顶角对红外探测的影响主要在2.7μm以下波段,探测波长大于2.7μm可不考虑太阳的影响。目标在5 km以下、探测天顶角在60°以上继续增加时,探测波段变窄,不可探频段增宽;目标在10km以上,探测天顶角变化对探测影响很小。这些结论可用于指导卫星红外探测波段选择与探测结果分析。     

红外预警卫星最佳探测波段分析

为解决红外预警卫星在近中红外的最佳探测波段问题,采用建模仿真的方法获得了2～5μm波段范围内不同高度条件下火箭尾焰目标的红外辐射光谱特性,利用MODTRAN软件包计算了典型大气条件下同样波段范围内不同高度处的大气透过率和地球/大气背景红外辐射光谱特性,在此基础上计算了目标背景之间的对比度.通过分析目标背景对比度的变化规律可知:随着飞行高度的增加,目标背景对比度会先增大后减小,但无论在什么飞行高度,2.63～2.83μm和4.18～4.50μm波段的目标背景对比度都较大,比较适合目标探测,并且这两波段还具有更加精细的波段结构,实际应用中可根据探测需求选择更小的波段范围并确定相应的中心波长.     

地基多通道微波辐射计在大气遥感中的应用

地基多通道微波辐射计可实时探测大气微波辐射亮温并反演出大气温度、水汽密度、相对湿度和液态水廓线等。本文主要介绍了自主研制的地基多通道微波辐射计以及数据反演方法,同时将微波辐射计反演的大气参数与探空资料对比分析了反演精度,结果表明微波辐射计观测反演大气温度、湿度和液态水廓线具有很好的精度。同时辐射计可实时精确的探测反演大气边界层逆温,能够很好的探测到地表辐射逆温的强度和逆温厚度,这对研究大气边界层有着重要作用。     

大气透过率对红外系统作用距离的影响分析

红外系统的作用距离是评价系统探测能力的重要性能指标。研究了大气传输介质对中红外探测波段的影响,计算了典型飞行目标中红外辐射在大气中的传输,分析了红外系统作用距离随相对湿度和大气能见度的变化。结果表明:红外系统作用距离随相对湿度的增加而减小,随能见度的增加而增大。对于800 K的目标,在能见度小于8 km的浑浊大气中,8~12 μm 探测波段的作用距离大于3~5 μm。在中等及良好能见度时,8~12 μm探测波段的作用距离小于3~5 μm波段。为红外探测跟踪系统的设计、性能指标考核与评价提供参考。     

基于地基微波辐射计的大气参数廓线遥感探测

介绍了实时连续遥感探测大气温度廓线、湿度廓线和液态水含量廓线的地基微波辐射计。通过无线电气球探空测量的温度、湿度廓线、太阳辐射计测量的晴天水汽总量与微波辐射计探测结果的对比,证明该微波辐射计可以可靠地探测大气温度、湿度和水汽总量。通过对两个典型天气事件微波辐射计的观测数据分析表明：微波辐射计还可以监测云和天气变化的过程信息。     

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.     

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.     

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.     

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正Communications—VLSI Researches and industries of telecommunications have been growing rapidly in the last 20 years and will keep their high growing pace in the next decade.The involved researches and developments cover mobile communications,highway and last-mile broadband communication,domain specific communications,and emerging D2D M2M communications.Radio communication steps into its