平台惯导系统中的半球谐振陀螺

半球谐振陀螺仪(HRG)是一种高精度、高可靠、长寿命的新型固体振动陀螺仪。为了使陀螺可适用于平台惯导系统的应用,通过对半球陀螺控制电路的改进,提高了半球陀螺的动态特性、带宽、精度等性能指标,测试结果表明,半球陀螺的动态测量范围达到-60~+60(°)/s;带宽扩展到≥75 Hz;漂移达到0.06(°)/h,满足了平台惯导系统的应用需求。     

力反馈模式半球谐振陀螺幅度控制方法优化

半球谐振陀螺(HRG)幅度控制环路用于陀螺的振动激发和振动幅度维持,工作于力反馈模式的半球谐振陀螺,其标度因数与陀螺振动幅度成正比。该文对半球陀螺力反馈模式工作原理进行了理论推导,然后分析了传统幅度控制方式受外界温度变化、电子元器件老化等原因影响,将会导致半球陀螺标度因数发生变化,最后提出了半球陀螺幅度控制的优化方法,在实现相同标度因数稳定性的的情况下,大幅降低电路实现难度。     

检测误差对半球谐振陀螺进动因子的影响分析

全角(WA)模式的半球谐振陀螺(HRG)进动因子只与球壳谐振子的物理尺寸有关,但由于读出电极非正交耦合及间隙失配、检测电路增益误差等检测误差,导致进动因子的周向一致性退化。该文首先对理想半球谐振陀螺的进动因子进行了理论推导,然后针对检测误差对进动因子的影响进行了分析,结合具体的全角模式控制电路与算法,提出了检测误差的校正方法,最后通过实验验证了该校正方法的有效性。实验结果表明,进动因子的周向一致性提升了2个数量级。     

基于频率解调的半球谐振陀螺控制系统设计

与力平衡模式相比,半球谐振陀螺的全角模式具有测量范围大及线性度高等优点。该文针对现有全角模式解调方案里驻波方位角计算过程中存在的精度损失,以及输出对温度变化敏感等问题,以行波线性叠加原理为基础,提出基于顺时针、逆时针行波同步频率解调的半球谐振子驻波信息解算方法。设计基于频率解调的全角模式半球谐振陀螺多回路控制方法,实现驻波的频率、幅度及正交控制。针对现场可编程门阵列(FPGA)电路算法优化难及浮点运算精度低等问题,设计并实现了现场可编程门阵列+数字信号处理(FPGA+DSP)双核心半球谐振陀螺数字控制电路。通过实物实验验证了该文提出的控制方案及数字控制电路的有效性。实验结果表明,此方法可减小由温度波动引起的谐振频率改变对陀螺输出的影响。     

MEMS半球谐振陀螺的角速度积分及其FPGA设计

微电子机械系统(MEMS)半球谐振陀螺是MEMS微陀螺领域的研究热点,能工作在角速度积分模式下,具有体积小、质量轻、功耗低、成本低、对称性高、Q值高,以及精度高等优点.文章给出了一种微型半球谐振陀螺的结构,研究了其工作原理以及检测方法,设计了一种数字式MEMS半球谐振陀螺仪的角速度积分工作模式方案及其FPGA实现方法,以完成目前MEMS半球谐振陀螺的角速度积分模式的控制与检测工作.     

基于平板电极的半球谐振陀螺全角技术研究

全角模式下的半球谐振陀螺是速率积分陀螺,具有测量范围宽、带宽高和精度高等特点。该文对由谐振子和平板电极组成的两件套半球谐振陀螺的全角模式进行了研究,介绍了全角模式振型控制与信号解算方法;通过FPGA+DSP的构架,实现了全角模式半球谐振陀螺振型控制,并解算了驻波方位角。实验数据证实,研制的两件套半球谐振陀螺样机能够实现速率积分陀螺的功能,测量范围达±400 (°)/s,陀螺最大系统漂移20 (°)/h。相对于力平衡模式半球谐振陀螺,其拓宽了半球谐振陀螺的测量范围,为进一步提升全角半球谐振陀螺的精度奠定了基础。     

半球谐振陀螺快速启动技术研究

半球谐振陀螺是一种新型振动陀螺仪,在装备领域有着广泛的应用前景。制造误差、干扰源及工作环境的变化影响了半球谐振陀螺的快速启动性能。该文分析了半球谐振陀螺输出的影响因素,讨论了谐振子品质因数(Q)值特性、装配、温度及信号干扰对快速启动性能的影响,并针对敏感器制造和信号处理进行了优化改进。结果表明,优化改进后的半球谐振陀螺可在通电3 min内达到稳定,相比改进前的大于1 h有显著提升。     

Cordic算法在半球陀螺中的应用及实现

半球谐振陀螺仪是一种新型长寿命、高可靠和高精度固体振动陀螺仪,其谐振频率会随环境温度的改变而变化,这种变化会对陀螺的控制精度产生不利影响。在介绍半球谐振陀螺基本控制原理的基础上,提出了一种基于Cordic算法的数字锁相环(DPLL),并给出Cordic算法的原理及在现场可编程门阵列(FPGA)上的设计方法。通过Modelsim仿真软件给出了时序仿真结果,系统主时钟20 MHz,频率精度为0.004 6 Hz,相位精度为0.06°,7.2万门FPGA的资源利用率为65%。性能测试结果表明,在4.5~5kHz内,该低频数字锁相环实现了对半球陀螺频率、相位缓慢变化的精确跟踪功能。     

半球谐振陀螺总剂量辐照效应性能研究

半球谐振陀螺是一种高可靠的哥氏振动陀螺,在宇航领域有广泛的应用前景。该文研究了在空间辐照环境下总剂量辐照效应对半球谐振陀螺性能的影响,分析了总剂量辐照效应对半球谐振陀螺不同功能模块的影响,包括陀螺敏感头、信号检测电路及控制电路,并进行了总剂量辐照试验验证。结果表明,100 krad(Si)的总剂量辐照对半球谐振陀螺的性能无明显影响,半球谐振陀螺的抗辐照能力能够满足高轨道航天器的应用需要。     

BP神经网络在半球谐振陀螺仪零偏温度补偿中的应用

半球谐振陀螺仪(HRG)的核心部件(半球谐振子)容易受到温度变化的影响,从而导致陀螺仪输出产生漂移,很大程度上限制了半球谐振陀螺仪精度的提升,因此需要对陀螺仪零偏进行补偿。首先结合半球谐振陀螺仪的工作原理对其零偏漂移产生的机理进行分析,利用最小二乘法和反向传播(BP)神经网络建立了半球谐振陀螺仪零偏漂移模型,同时利用建立的模型进行了零偏补偿,补偿效果显著。实验结果表明:补偿后零偏稳定性相较于补偿前和最小二乘法分别提高了80%和60%以上,BP神经网络有着比最小二乘法更优的非线性拟合能力。     

聚对苯撑苯并双(口恶)唑发光及其器件制备

采用光谱技术,研究了聚对苯撑苯并双(口恶)唑(PBO)溶液的光敏发光特性,并用相对法估算出溶液发光效率在50%范围.结合光谱技术、半导体电学和电化学等研究手段,具体研究了以PBO为发光层的单层电致发光器件,研究结果显示,电致发光与薄膜的光致发光有具有相同的发光中心,峰值位于510 nm左右.同时发现,由于存制备过程中不同处理条件使得不同厚度薄膜残留的掺杂物质浓度不同,从而引起薄膜的导电性的不同.使得器件的阈值场强随PBO厚度的减小而逐渐增加.     

系统级封装新型埋入式电源滤波结构的研究

在高密度小尺寸的系统级封装(SiP)中,对供电系统的完整性要求越来越高,多芯片共用一个电源网路所产生的电压抖动除了会影响到芯片的正常工作,还会通过供电网路干扰到临近电路和其他敏感电路,导致芯片误动作,以及信号完整性和其他电磁干扰问题.这种电压抖动所占频带相当宽,几百MHz到几个GHz的中频电源噪声普通方法很难去除.结合埋入式电容和电源分割方法的特点,提出一种新型高性能埋入式电源低通滤波结构直接替代电源/地平面.研究表明,在0.65～4GHz的频带内隔离深度可达-40～75 dB,电源阻抗均在0.25ohm以下,实现了宽频高隔离度的高性能滤波作用.分别用电磁场和广义传输线两种仿真器模拟,高频等效电路模型分析这种低通滤波器的工作原理以及结构对隔离性能的影响,并进行了实验验证.     

Emerging interconnects: a state-of-the-art review and emerging solutions

Aluminium was a primary material for interconnection in integrated circuits (ICs) since their inception. Later, copper was introduced as interconnect material which has better metallic conductivity and resistance to electromigration. As the aggressive technology scaling continues, the copper resistivity increased because of size effects, which causes increase in delay, power dissipation and electromigration. The need to reduce the resistor-capacitor??????? delay, dynamic power utilisation and the crosstalk commotion is as of now the fundamental main impetus behind the presentation of new materials. The purpose of this paper is to do a survey of interconnect material used in IC from introduction of ICs to till date. This paper studies and reviews new materials available for interconnect application which are optical interconnects, carbon nanotube (CNT), graphene nanoribbons (GNRs) and silicon nanowires which are alternatives to copper. While doing a survey of interconnect material, it is found that multiwalled CNTs, multilayer GNR and mixed CNT bundles are promising candidates and are ultimate choice that can strongly address the problems faced by copper but on integration basis copper would last for coming years.     

Arsenic deposition as a precursor layer on silicon (211) and (311) surfaces

We investigate the properties of arsenic (As) covered Si(211) and Si(311) surfaces by analyzing data from x-ray photoelectron spectroscopy (XPS) and low-energy electron diffraction (LEED) images. We then create a model using total surface energy calculations. It was found that both Si(211) and Si(311) had 0.68±0.08 surface As coverage. Si(211) had 0.28±0.04 Te coverage and Si(311) had 0.24±0.04 Te coverage. The Si(211) surface replaces the terrace and trench Si atoms with As for a lower surface energy, while the Si edge atoms form dimers. The Si(311) surface replaces all terrace atoms and adsorbs an As dimer every other edge site. These configurations imply an improvement in the mean migration path from the bare silicon surface by allowing the impinging atoms for the next epitaxial layer, tellurium (Te), to bind at every other pair of edge atoms, and not the step terrace sites. This would ensure a nonpolar, B-face growth.     

光子晶体微腔发光二极管

光子晶体微腔因其具有增强自发辐射、定向输出和单模工作的能力而受到广泛关注。介绍了光子晶体微腔发光二极管的基本原理、设计、特性、制作及其典型器件。     

用于单光子TOF测量的时间-幅度变换器

基于新型共源共栅电流源的积分方法,设计了一种用于单光子飞行时间(TOF)测量的时间-幅度变换器(TAC)。该方法有效简化了TAC电路结构,减小了TAC占用面积,显著提高了TOF的满量程范围(FSR)。采用0.18 μm标准CMOS工艺设计。集成TAC的单光子探测器像素单元的填充因子可达到26.8%。后仿真结果表明,该TAC在120 ns的FSR内具有230 ps的定时分辨率,微分非线性(DNL)低于0.05 LSB,积分非线性(INL)低于1.1 LSB。蒙特卡洛仿真表明,512个TAC像素间的不均匀性低于0.5 %。该TAC非常适用于高密度时间相关的单光子计数(TCSPC)探测器阵列。     

Comparative study of maximum power point tracking techniques for hybrid renewable energy system

The power generation demand is increasing day-by-day throughout the world, therefore, the use of hybrid systems becomes a significant solution. The hybrid renewable energy system (HRES) is used for delivering power in various regions in order to overcome intermittence of wind and solar resources. Because of increasing environmental problems, for example, greenhouse gas emission and energy cost have interested novel research into substitute methods in favour of electrical power generation. Maximum Power Point Tracking (MPPT) control method is a vast deal of novel research used for enhancing the efficiency of HRES. The authors have revealed that the hybrid techniques i.e. Global MPPT, fuzzy-neuro systems, Adaptive Neuro-Fuzzy Inference System (ANFIS), Perturbed and Observe (P&O) + Adaptive Neural Network (ANN) etc. can provide best results as compared to other MPPT control methods. This paper offering a state of art review of MPPT control techniques for HRES.     

Joint estimation of TOA and DOA in IR-UWB system using a successive propagator method

Impulse radio ultra-wideband (IR-UWB) ranging and positioning require accurate estimation of time-of-arrival (TOA) and direction-of-arrival (DOA). With receiver of two antennas, both of the TOA and DOA parameters can be estimated via two-dimensional (2D) propagator method (PM), in which the 2D spectral peak searching, however, renders much higher computational complexity. This paper proposes a successive PM algorithm for joint TOA and DOA estimation in IR-UWB system to avoid 2D spectral peak searching. The proposed algorithm firstly gets the initial TOA estimates in the two antennas from the propagation matrix, then utilises successively one-dimensional (1D) local searches to achieve the estimation of TOAs in the two antennas, and finally obtains the DOA estimates via the difference in the TOAs between the two antennas. The proposed algorithm, which only requires 1D local searches, can avoid the high computational cost in 2D-PM algorithm. Furthermore, the proposed algorithm can obtain automatically paired parameters and has better joint TOA and DOA estimation performance than conventional PM algorithm, estimation of signal parameters via rotational invariance techniques algorithm and matrix pencil algorithm. Meanwhile, it has very close parameter estimation to that of 2D-PM algorithm. We have also derived the mean square error of TOA and DOA estimation of the proposed algorithm and the Cramer-Rao bound of TOA and DOA estimation in this paper. The simulation results verify the usefulness of the proposed algorithm.     

超宽带脉冲信号的光学生成方法研究

近年来超宽带(UWB)通信技术迅猛发展,在测量、雷达技术、民用和军事无线通信中有着重要的应用,UWB-over-fiber技术已经成为目前研究的热点,其中就包括UWB脉冲信号的产生方法。区别于传统的电子学方法,光子学产生方法不受电子瓶颈制约,可以实现很高的带宽,并且具有抗电磁干扰、重量轻、结构紧凑的优点。通过对比国内外本领域研究成果,讨论及总结了以下三种原理的UWB脉冲信号的光学生成方法:1)相位调制-强度调制转换(PM-IM);2)半导体光放大器(SOA)的非线性效应;3)频谱塑形和色散所致频域-时域映射,然后对各种方案进行了对比分析。     

一种基于分段CRC的LDPC译码的改进算法

级联多个循环冗余校验(CRC)的LDPC译码算法有效地改善了译码的收敛特性.然而在其译码算法中,当CRC检测的整体漏检概率不够低时,出现误码平台.因此,该文提出了改进算法,通过减少在译码算法中CRC检测的次数,降低整体漏检概率,提高了误码性能.仿真表明改进的算法提高了误码性能,译码复杂度也增加不大.