大气湍流对激光雷达跟踪角误差的影响

本文讨论了大气湍流引起的强度起伏和相位起伏对激光雷达跟踪系统测角精度的影响，得强度起伏导致的对数振幅方差和相位起伏导致的到达角方差，计算了强度起伏和相位起伏对跟踪系统的接收信噪比，角误差的影响，结果表明，大气湍流引起的角误差与仰角、距离等因素有关。     

Combined optical fiber interferometric sensors for the detection of acoustic emission

A type of combined optical fiber interferometric acoustic emission sensor is proposed. The sensor can be independent on the laser source and make light interference by matching the lengths of two arms, so it can be used to monitor the health of large structure. Theoretical analyses indicate that the system can be equivalent to the Michelson interferometer with two optical fiber loop reflectors, and its sensitivity has been remarkably increased because of the decrease of the losses of light energy. PZT is powered by DC regulator to control the operating point of the system, so the system can accurately detect feeble vibration which is generated by ultrasonic waves propagating on the surface of solid. The amplitude and the fre- quency of feeble vibration signal are obtained by detecting the output light intensity of interferometer and using Fourier transform technique. The results indicate that the system can be used to detect the acoustic emission signals by the fre-quency characteristics.     

铆钉防护对其导电性能影响研究

本文分析某型直升机在铆接过程中,对于铆钉做电搭接时,根据技术文件规定需要对铆钉进行了去氧化防护层处理之后在进行铆接。在此过程中,工人无疑增加了工作量,降低了工作效率,因此为探究铆钉防护对其导电性能是否影响很大,进行了铆钉防护对其导电性影响试验,通过试验发现分别用有无表面氧化防护层的两种不同的铆钉HB6231半圆头钉和HB6315埋头钉进行铆接后,经过仪器测试后,其电阻值并没有较大波动,由此证明铆钉有无表面氧化防护层对其导电性能无影响。     

Travelling dipole domains and fluctuations for a current instability due to Bragg scattering

We investigate the stability of uniform and nonuniform current states for a model in which Bragg scattering of hot electrons leads to bulk negative differential conductivity. The system is described by phenomenological balance equations for momentum and energy densities of the carriers. For fixed total current, we find a family of periodic travelling-wave solutions and a solitary solution (dipole domain) which can be stabilized by coupling to a suitable external circuit, if the static domain impedance is negative. The model describes therefore a discontinuous nonequilibrium phase transition to a large-amplitude domain. In order to study fluctuations, we add stochastic forces to the balance equations and discuss the resulting fluctuation spectra.     

一种功率型光耦合单片集成光电检测电路

针对功率型光电检测电路微弱光信号检测和功率输出的需求,研制了一种集成光电探测传感器和信号处理电路,且带功率驱动功能的单片光电检测电路.从理论上探讨了光电探测器的工艺兼容与系统噪声匹配,设计了专用的光电探测器以及适用于功率型光电集成电路(OEIC)的信号处理单元.采用B6035双极工艺,进行了版图设计和流片测试.测试结果表明,该电路的电源电压工作范围、静态功耗和传输延迟时间等综合性能优于同类型混合组装电路.     

基于高导热碳纤维的HgCdTe大面阵探测器热适配结构在空间红外遥感相机中的应用

HgCdTe面阵探测器是空间红外遥感相机的关键部件,随着性能需求的不断提高,器件的规模尺寸不断扩大。HgCdTe面阵探测器在常温下与承载板进行装配,但在深冷状态下工作,需要耐受200 K左右的温度波动。由于探测器与承载板的线膨胀系数不匹配,温度波动会引起探测器翘曲变形,变形严重时,将导致探测器损伤。提出基于高导热碳纤维的HgCdTe大面阵探测器热适配结构,以碳纤维的轴向高热导率降低结构热阻,以碳纤维的极小抗弯截面模量实现热适配结构两端面间的刚度解耦。相对于探测器与承载板直粘,引入基于高导热碳纤维的热适配结构后,探测器与承载板间的热阻仅增加了约1%,而探测器热失配翘曲变形衰减了99.9%,解决了大面阵探测器与承载板间的热失配翘曲变形损伤问题。并对基于碳纤维的热适配结构制备工艺方案进行了简单介绍。     

基于双光纤光栅的加速度传感探头结构的设计

分布式光纤光栅加速度传感技术对微弱振动测量分析及其故障诊断具有重要的实用价值。采用副载波调频、波分复用技术提出了一种分布式光纤布喇格光栅加速度测量系统,并进行了基于双光纤布喇格光栅的加速度传感探头结构的设计。该传感探头具有尺寸小,质量轻,不受电磁干扰等优点,有较高的测量灵敏度和分辨率,而且能自动消除温度噪声和相位噪声的影响。     

Manifestation of percolation conductivity of short-channel field-effect transistors in the spectrum of shallow interface states

The effective density of shallow interface states N _ss is investigated in the temperature range T=77–300 K using the field-effect method in short-channel (0.5–5 μm) Si-MNOS and GaAs-based FET’s with high (greater than 10¹² cm⁻²) concentrations of built-in charge in the subgate insulator. A peculiarity of the density of electronic states N _ss was found having the form of a peak, which manifests itself more distinctly at lower temperatures, higher concentrations of built-in charge, and shorter gates. The peak was observed at the same values of the channel conductance G∼q ²/h, regardless of variations in the above-enumerated parameters, the thickness of the sub-gate insulator, and the channel-length-to-width ratio. This means that the energy depth of the peak (∼40–120 meV) varies in proportion to T, which contradicts the current understanding of the interface states caused by both the fluctuation potential (FP) and surface defects or traps. The results are interpreted within the framework of percolation theory applied to the conductivity of strongly disordered systems. The N _ss peculiarity is associated with a transition from the conductivity of a two-dimensional effective solid, which occurs when the fluctuation potential is strongly screened by surface electrons, to conductivity via a quasi-one-dimensional potential trough organized by local regions with reduced surface potential under conditions of a strong fluctuation potential. Fiz. Tekh. Poluprovodn. 31, 1460–1467 (December 1997)     

Changes in the characteristics of CuInGaSe2 solar cells under light irradiation and during recovery: degradation analysis by the feeble light measuring method

Changes in the characteristics of CuInGaSe₂ solar cells in response to light irradiation were investigated. Then these changes, which suggest long-term degradation, were clarified using the measurement technique by feeble light. The thin-film cell of this type is considered to be “ever stable”. A stable result over the short term was also obtained in the light accelerated test of 2-SUN performed in this experiment. On the other hand, it was found that the characteristics measured with feeble light show a remarkable change over time. As a result of measuring at 0.065–105 mW/cm² light intensity, the change rate of cell output power was so intense the measurement light was weak. This finding reflects the increase in an internal defect and suggests a possibility that light irradiation exerts the influence on long-term cell performance. Moreover, by measuring with feeble light, we found that the changed output recovers by reverse voltage application. The phenomenon of recovery up on comparatively low reverse voltage can be considered as an application for maintaining stability.     

光电跟踪系统力矩波动干扰抑制的研究

光电跟踪系统的力矩波动是影响其跟踪精度的噪声的角度一个关键问题.基于某光电跟踪控制系统动态模型,从抑制噪声的角度分析了加入电流环对抑制力矩波动的影响,同时还分析了系统速度、电流两环闭环带宽与力矩波动抑制之间的关系.分析表明,加入电流环后的光电跟踪系统抑制力矩波动的能力明显增强,同时较高的速度回路带宽有利于抑制力矩波动引起的干扰,且在速度带宽一定的情况下增加电流用环带宽对抑制力矩波动也有一定作用.因此,在设计光电跟踪系统时,在不影响系统稳定性的前提下应选用尽可能大的速度及电流闭环带宽.     

Adaptive dispersion equalization by monitoring relative phase shiftbetween spacing-fixed WDM signals

This paper proposes a novel adaptive dispersion equalization system that equalizes the temperature-induced dispersion fluctuation in long-span ultra-high-speed optical transmission systems. The system monitors the dispersion fluctuation by measuring the relative delay between two wavelength division multiplexed (WDM) signals, and equalizes the dispersion fluctuation by wavelength tuning. A variable-dispersion equalizer can be used instead of wavelength tuning. Adaptive equalization is successfully demonstrated in 40-Gb/s (8-ps-RZ pulses) 400-km transmission. Furthermore, the proposed equalization system is shown to be applicable to WDM systems that use dispersion and dispersion slope compensation. Since the sensitivity to the dispersion fluctuation is improved by extending the wavelength spacing of the signal and monitor channels, the system is shown to operate even when polarization-mode dispersion (PMD) of the transmission fiber must be taken into account     

Influence on Conductivity of Polyparaphenylene by Chemical Doping and Ion Implantation

１ＩｎｔｒｏｄｕｃｔｉｏｎＡｓａｎｅｗｋｉｎｄｏｆｃｏｎｄｕｃｔｉｎｇｐｏｌｙｍｅｒ,ｐｏｌｙｐａｒａｐｈｅｎｙｌｅｎｅ（ＰＰＰ）ｉｓｔｈｅｐｏｉｎｔｏｆａｔｅｎｔｉｏｎｆｏｒｍａｎｙｓｃｈｏｌａｒｓｄｕｅｔｏｉｔｓｌｏｗｃｏｓｔ,ｓｉｍｐｌｅｓｙｎ...     

激光棒中温度分布的时间特性

计算了在光泵期间均匀光泵引起激光棒中温度分布随时间的变化。单次脉冲可以忽略棒的热传导,温度分布完全由光泵决定。求出连续运转和重复脉冲运转的稳态建立时间,温度分布和重复脉冲运转的温度波动。对典型的YAG器件给出了具体的数值。     

地面RCS起伏特性模拟及对ATI检测性能的影响

在假定目标RCS起伏为高斯形状频谱特性的前提下,将高斯白噪声通过一个高斯谱特性的低通滤波器来模拟目标RCS起伏特性。首先用康斯坦尼兹法设计了低通滤波器,并根据地杂波等效速度的不同,得到一组不同的滤波器响应,进而实现了背景RCS起伏程度不同的地杂波的模拟。然后以该地杂波为背景,采用ATI方法进行动目标检测,分析了地面背景RCS起伏特性对动目标检测性能的影响。计算机仿真结果表明：在一定的虚警概率下,当不考虑接收机噪声时,随着RCS起伏加剧,动目标径向最小可检测速度增大。最后得到结论：用基于ATI方法进行动目标检测时,若不考虑雷达接收机噪声,则地面背景RCS起伏特性是影响最小径向可检测速度的主要因素。     

半导体单道剂量仪的硬件设计

半导体单道剂量仪是一种测量仪器。采用半导体探头作为辐射探测器,将辐射信号转化成微弱电流,前置级对微弱信号进行积分,定时测量出电压值,此电压值正比于剂量值。主板以单片机为核心,在其外部扩展了ADC,显示模块,E2PROM,打印机、键盘等,具有数据处理、显示、储存、打印、报警值设置、校正系数设置、测量时间设置以及报警等功能。     

一种分布式发电功率时间序列波动性量化评估方法

未来智能电网将接纳越来越多的分布式能源,而分布式能源的广泛接入具有提高系统的能源效率、经济性、韧性以及可持续性的潜力。然而,以风力发电和光伏发电为主的分布式能源由于其固有的波动特性,在大规模接入电网时会给系统带来诸多问题。因此,定量刻画分布式发电功率的波动性对于现代电力系统而言至关重要。基于此,该文借助时间窗、包络线和勒贝格积分,通过提取分布式发电功率中高频信息和变化趋势的波动性特征,定义了量化分布式发电功率波动性的指标——波动率。通过检验风电功率时间序列的波动性、验证平滑效应以及与预测误差和已有指标进行对比分析,验证了所提出的波动率在衡量分布式发电功率波动性的有效性。     

内腔He—Ne激光器功率稳定性与方向漂移的研究

本文认为，温度及环境气流的变化是影响内腔He—Ne激光器功率稳定性和方向源移的最重要的原因，并采取了相应的改善措施，取得了较好效果。     

Explaining the effects of processing on the electrical properties of PEDOT:PSS

By simultaneously measuring the Seebeck coefficient and the conductivity in differently processed PEDOT:PSS films, fundamental understanding is gained on how commonly used processing methods improve the conductivity of PEDOT:PSS. Use of a high boiling solvent (HBS) enhances the conductivity by 3 orders of magnitude, as is well-known. Simultaneously, the Seebeck coefficient S remains largely unaffected, which is shown to imply that the conductivity is improved by enhanced connectivity between PEDOT-rich filaments within the film, rather than by improved conductivity of the separate PEDOT filaments. Post-treatment of PEDOT:PSS films by washing with H₂SO₄ leads to a similarly enhanced conductivity and a significant reduction in the layer thickness. This reduction strikingly corresponds to the initial PSS ratio in the PEDOT:PSS films, which suggests removal and replacement of PSS in PEDOT:PSS by HSO₄⁻ or SO₄²⁻ after washing. Like for the HBS treatment, this improves the connectivity between PEDOT filaments. Depending on whether the H₂SO₄ treatment is or is not preceded by an HBS treatment also the intra-filament transport is affected. We show that by characterization of S and σ it is possible to obtain more fundamental understanding of the effects of processing on the (thermo)electrical characteristics of PEDOT:PSS.     

Performance degradation induced by polarization-dependent loss in optical fiber transmission systems with and without polarization-mode dispersion

The performance degradation caused by polarization-dependent loss (PDL) in optical fiber transmission systems in both the absence and presence of polarization-mode dispersion (PMD) is studied. First a simple theory is given to show how PDL affects the system performance and then extensive simulation results are presented. We show that PDL causes a much larger fluctuation of optical-signal-to-orthogonal-noise ratio (OSNR/sub ort/) than that of optical-signal-to-parallel-noise ratio (OSNR/sub par/), but OSNR/sub par/ has a much larger impact on the system performance than OSNR/sub ort/. We find that when there is no PMD, the system performance degradation induced by PDL can be effectively reduced by suppressing OSNR/sub par/ fluctuation. However, the presence of PMD in the system could significantly reduce the efficiency of the PDL mitigation technique, especially the mitigation technique that suppresses the OSNR/sub par/ fluctuation.     

频带FSO-OFDM系统建模与LS信道估计研究

本文首先设计了频带FSO-OFDM系统模型,阐述了其发射和接收部分工作原理,介绍了大气散射信道模型。通过对散射信道的仿真,发现FSO-OFDM系统对弱散射有很强的抵御能力,当散射强度强时,系统性能就会急剧恶化,由于提高发射功率不能有效的降低散射对系统的影响,为了解决此问题,本文利用璩算法对导频处大气信道进行估计,最后通过插值恢复出数据处信道参数,通过仿真进行验证,结果表明,通过合理设计导频序列,IS算法能够很好的改善强散射信道中频带FSO-OFDM系统性能。