机载北斗/GPS/SINS组合导航系统软硬件设计

针对单一导航导航系统在导航精度、稳定性、设备成本以及导航信息完备性等方面的局限性,设计了卫星导航/惯性导航组合导航系统。针对GPS导航系统受制于人及北斗导航系统发展尚不完善的特点,提出了基于北斗/GPS/SINS的军用机载组合导航系统软硬件设计。搭建了北斗/GPS/SINS组合导航系统硬件平台,采用基于不确定度的加权平均数据融合算法提高组合导航系统的导航可靠性和准确性。仿真结果表明,该组合导航系统稳定性好,可靠性高,定位准确。     

Kalman滤波辅助的室内伪卫星相对定位算法

在室内伪卫星独立定位系统中, 伪卫星以及接收机的钟差会给定位精度带来非常大的误差. 针对这一问题, 提出了一种适用于室内环境的相对定位算法. 使用Kalman定位算法粗略计算接收机位置, 获得粗略基线, 建立室内相对定位模型, 得到载波相位双差和伪距双差. 载波相位双差通过互补Kalman滤波器来平滑伪距双差, 进一步得到精确基线, 获得接收机精确位置, 并将其代替Kalman定位算法的校正结果, 对接收机进行下一状态预测. 实验结果表明, 该算法具有较高的定位精度, 定位误差在20 cm以内. 关键词： 伪卫星 相对定位 双基线 Kalman滤波     

一种基于多源收发异体结构的室内移动目标超声定位系统

提出一种高性能超声定位系统,采用红外和无线信号同时作为同步信号构成收发异体的定位结构,采用伪随机M序列进行载波扩频,形成码分多址的多基站收发机制,通过设计广角探头来扩大作用范围,设计温度补偿电路提高测量精度.本系统能实现10 Hz的测量速率和厘米级的测量精度,能有效实现室内移动目标的高精度定位.     

无人机侦察多目标实时定位技术研究

目标定位是无人机侦察系统中至关重要一步。为增强无人机侦察目标定位的实时性、提高定位精度及侦察效率,提出一种多目标实时定位的方法,建立主次目标定位几何关系及坐标转换模型,结合已知数据信息求取各目标大地坐标,并用蒙特卡洛法分析目标定位误差。最后,基于即将组网成功"北斗二代"卫星导航系统对无人机空中定位,同时采用递归最小二乘算法滤波处理,提高了目标定位精度。研究及实验结果表明,北斗导航定位能够有效提高无人机空中定位精度,且有望达到厘米级精度,同时采用RLS滤波处理能使目标定位精度提高10 m左右。该方法能够有效增强无人机定位实时性,提高定位精度及侦察效率。     

基于惯性信息辅助的北斗动动定位方法的研究

针对北斗动动定位中接收机信号易受遮挡导致无法实时准确定位的问题,对复杂信号条件下的动动定位测试进行了研究,提出了一种利用惯性信息辅助解算动态模糊度的方法,即一种将运动载体的惯导信息与北斗测量信息相结合,实现两运动载体之间精确动态相对定位的算法。通立基于载波相位双差的观测模型,采取融合滤波算法,讨论在在不同卫星数目下的模糊度求解方法。在此基础上,利用实地车载试验完成了对上述组合定位方法的试验验证以及精度测试,事后着重对各历元数据进行解算,对定位精度、可用性进行了研究。结果表明,基于惯性信息辅助的北斗动动定位可用性指标变好,定位精度有一定的提高。     

基于影像实时处理的加油对接段辅助对准技术北大核心CSCD

针对空中加油试飞中加油对接困难的问题,设计了一种基于影像实时处理的加油对接段辅助对准系统,通过影像测量技术计算受油头与加油锥套中心的精确相对位置,实现位置参数与视频画面实时同步显示,用于空中加受油对接辅助对准。并对复杂光学条件下锥套跟踪技术、基于约束的像机标定技术和加受油组件相对位置实时测量等关键技术进行研究。实验结果表明,该算法可实现空中复杂环境下锥套图像快速、稳定识别与跟踪;采用双目视觉前方交会测量实时计算加油锥套与受油头相对位置,与事后处理结果对比分析,精度优于0.1 m,可辅助飞行员进行空中加油对接操作,提高加受油对接成功率。     

机载卫星制导武器直接瞄准攻击研究

 介绍了卫星制导武器直接瞄准攻击方式在对地精确打击中占据的关键位置,阐述了卫星制导武器直接瞄准攻击方法的原理。由于卫星制导武器直接瞄准攻击对目标定位要求较高,采用常用定位手段已不能满足系统对目标定位的要求,分析了使用相对GPS制导成为卫星制导武器直接瞄准攻击的关键的原因。相对GPS制导误差主要包括采用载机和武器相对GPS定位误差以及传感器对目标的相对定位误差,分别对两者的定位精度进行了分析和推导。仿真结果表明：这两者的综合误差理论值小于7.5 m,满足卫星制导武器在直接瞄准攻击中对目标定位的需求。     

近景大视场角分区域标定方法研究

针对飞行试验测量视场大相机标定精度低的问题,提出一种高精度CCD相机分区域标定方法。该方法首先通过将标靶均匀布置在摄像机视场内,使得标靶尽可能均匀错落地充满整个视场范围,再结合人眼判读的方式求解靶标的像面位置,最终与全站仪三维坐标形成精确的空间标定点集。接着,将像平面按横向方向等间距分割成Ｎ个区域,并结合后方交会的方法分别对每个子区域进行相机参数的计算。实验结果表明：经过分区域标定,相机采集点的总误差比单区域标定法降低了4％(Ｎ＝3)。算法可实现指定区域的相机参数计算,基本满足中高等精度的工业测量要求。所本文研究可应用于位置相对固定不变的工业视觉测量,特别是大工件测量领域。     

基于异面交会的空中运动目标定位算法及误差分析

介绍了空中运动目标定位测量的经纬定位仪单站定向和双站异面交会定位原理,并对影响定向和定位结果的各个因素进行了误差分析和仿真.结果表明,交会角在[40°,165°]时.测量精度有明显地改善,为组网测量布站提供了依据.黑火药爆炸试验测量结果验证了该方法的可行性和测量精度.     

微靶装配中靶球几何量的高精度测量

为满足微靶装配过程中靶球和靶腔相对位置的严格的要求,保障惯性约束聚变实验的成功,针对机器视觉的几何量测量精度很难达到5 m以下的不足,设计了利用具有亚m级精度的激光共焦测头对装配中的靶球进行采点扫描以获取其尺寸和位置的非接触测量方法,借助于在线监测系统运动轴的高精度定位,通过上下两个激光共焦测头的组合测量,并采用一种快速而准确的基于点阵插值细分和目标两级提取的测量算法,使在线监测系统的球体几何量测量精度达到了2 m。     

Self-organization of five species in a cyclic competition game

Cyclic competition game models, particularly the “rock–paper–scissors” model, play important roles in exploring the problem of multi-species coexistence in spatially ecological systems. We propose an extended “rock–paper–scissors” game to model cyclic interactions among five species, and find that two of the five can coexistent when biodiversity disappears, which is different from the “rock–paper–scissors” game. As the number of fingers is five, we named the new model the “fingers” game, where the thumb, forefinger, middle finger, ring finger, and little finger cyclically dominate their subsequent species and are dominated by their former species. We investigate the “fingers” model in two ways: direct simulations and nonlinear partial differential equations. An important finding is that the number of species in a cyclic competition game has an influence on the emergence of biodiversity. To be specific, the “rock–paper–scissors” model is in favor of maintaining biodiversity in comparison with the “fingers” model when the variables (population size, reproduction rate, selection rate, and migration rate) are the same. It is also shown that the mobility and reproduction rate can promote or jeopardize biodiversity.     

Experimental study on downstep in Chinese intonation

Downstep in pitch contour of Chinese Putonghua is examined using subtly designed sentences by controlling tone combinations. The results show both automatic and nonautomatic downstep phenomena exist in Chinese. In non-automatic downstep, low tones compress downwards the pitch range of the following syllables. and the main influence of downstep is on topline. Low tone not only lower the topline behind it, but also raise the high tones before it, the effects are compatible with each other. In automatic downstep, the topline of pitch contour in intonational phrase is presented as a linear downtrend, but it differs among speakers due to the effect of personal stress practice. In comparison with downstep phenomenon in other tone or non-tone languages, the downstep ratio in Chinese is not constant, and the domain of downstep is not limited within the adjacent tones.     

Contrastive analysis on tone between Putonghua and Taiwan Mandarin

The differences of the pitch and duration of Chinese syllables between Putonghua （PTH） and Taiwan Mandarin （TM） were studied. The speech materials to be used are not only isolated syllables, but also sentences. The results reveal that： For the isolated syllables, T1 and T2 in TM are influenced by Minnan dialect, therefore their pitch are lower than those in PTH. T3 is fall-rise in PTH, while it is fall in TM. Moreover, the syllable duration sequence for different tone is T3〉T2〉T1〉T4 in PTH, while it is T1〉T2〉T3〉T4 in TM. For the syllables in sentences, T2 is mid-rise in PTH, while it is mid-level in TM. And the T3 is longer than T4 but shorter than T1 or T2 in PTH, while it is the shortest in TM. Furthermore the effects of prosodic phrase boundary on duration for different tones are almost the same in PTH, but the lengthening part of T1 or T2 is longer than that of T3 or T4 in TM.     

Abelian-Higgs phase of SU(2) QCD and glueball energy

It is shown that SU(2) QCD admits an dual Abelian-Higgs phase, with a Higgs vacuum of a type-Ⅱ superconductor. This is done by using a connection decomposition for the gluon field and the random-direction approximation. Using a bag picture with soft wall, we presented a calculational procedure for the glueball energy based on the recent proof for wall-vortices [Nucl. Phys. B 741(2006)1].     

High efficiency filtering using two-dimensional photonic crystal coupled cavity structures

Transmission spectra of coupled cavity structures (CCSs) in two-dimensional (2D) photonic crystals (PCs) are investigated using a coupled mode theory, and an optical filter based on CCS is proposed. The performance of the filter is investigated using finite-difference time-domain (FDTD) method, and the results show that within a very short coupling distance of about 3λ, where λ is the wavelength of signal in vacuum, the incident signals with different frequencies are separated into different channels with a contrast ratio of 20 dB. The advantages of this kind of filter are small size and easily tunable operation frequencies.     

Signal generation in an isotropic medium in scanning electron acoustic microscope

Based on the research in Ref. [5][Materials Science and Engineering, 1989; A122： 57 63], an improved model of heat source is set up, the different modes of Lamb wave in an isotropic sample generated by a chopped electron beam at frequency f are obtained with integral transform and normal function expansion method, and the output signal of PZT coupled at the back surface of the sample is found out. The generation mechanism of SEAM （Scanning Electron Acoustic Microscopy） signal is discussed. It shows that the SEAM is a near field imaging technique with high spatial resolution and its best lateral spatial resolution is about 2√2α （α is the radius of the focused electron beam）. Some of experimental results of SEAM images are presented in the paper and it shows that the spatial resolution of SEAM is better than 0.5 μm and smaller than the thermal diffusion length of the sample. Therefore the character of near field imaging in SEAM is also proved experimentally.     

Real-time restoration of rotational blurred image using gradient-loading

The key to the restoration of rotational motion blurred image is how to restore the image under a low cost and to correct the irreversibility of the degradation function matrix.Based on the special qualities of degradation function matrix and precise deduction in space-domain, we present a new approach using gradient-loading for restoration of rotational blurred image.By easily adding a gradient operator, the irreversibility of the original matrix is corrected and can be applied for inverse filtering then.Gradientloading is the optimized approach which combines the advantages of both the approaches using constrained least square filtering and traditional diagonal-loading.Compared with the approach using least square filtering, its peak signal-to-noise ratio (PSNR) is improved from 3.18 to 6.46dB, while the computing time is reduced to 1/2-1/3.Experimental results demonstrate the effectiveness, noise-resistibility, robustness, and low complexity of this approach, which make it more suitable for real-time environment.     

All-Optical Logic Device Using Bent Nonlinear Tapered Y-Junction Waveguide Structure

We propose an all-optical logic device made of a bent tapered Y-junction waveguide with a Kerr-type nonlinear interface. It could provide an AND gate, OR gate, and exclusive-OR (XOR) gate. We could obtain different transmission results by adjusting the bending angle. The numerical simulation results show that the device functions as AND, OR, and XOR gates.     

Real-time, continuous-wave terahertz imaging by a pyroelectric camera

Real-time, continuous-wave terahertz (THz) imaging is demonstrated. A 1.89-THz optically-pumped farinfrared laser is used as the illumination source, and a 124 × 124 element room-temperature pyroelectric camera is adopted as the detector. With this setup, THz images through various wrapping materials are shown. The results show that this imaging system has the potential applications in real-time mail and security inspection.