透过散射介质的结构光重构方法及特性分析

结构光透过生物组织、沙尘等强散射介质时历经多重散射,会改变原有相位信息和传播方向,破坏相干性,最后形成散斑。本文主要针对结构光重构特征和适用性进行分析,以条形结构光作为入射光,透过散射介质后,分别运用直接求逆法、相位共轭法和TVAL3法对其进行重构,并分析不同测量噪声水平下,三种方法对条形结构光的重构效果。仿真结果表明:测量噪声水平为0时,直接求逆法能得到较完美的重构效果;存在测量噪声且测量噪声水平小于0.025I时,TVAL3法能较好实现重构,而相位共轭法重构效果一直较差。同时,也运用三种方法实现了单点、三点的点光源重构。     

基于Vernier阳极微通道板光子计数探测器分割噪声

为消除微通道板光子计数探测器系统中电子噪声的干扰,研究了探测器分割噪声的来源,并提出利用COMSOL软件仿真计算分割噪声的方法.利用有限元方法对基于Vernier阳极探测器的成像过程进行三维建模,实现了一组5×5针孔阵列的模拟成像,计算出Vernier阳极分割噪声所产生的电子云质心位置的偏移量,验证了Vernier阳极探测器成像编码的正确性与仿真研究分割噪声的可行性.通过分析不同参量的阳极面板,利用数值拟合方法,得到电子云质心偏移量与阳极面板设计参量之间的关系.在固定面板参量的前提下,可以通过提高微通道板增益来有效降低分割噪声对质心位置偏移影响.     

外加条件及两种电子传输对量子点红外探测器噪声的影响

基于外加电场对电子漂移速度的影响,考虑激发能对微米尺度和纳米尺度电子传输的依赖,通过计算仿真研究了外加条件及两种电子传输对量子点红外探测器噪声的影响.结果表明:在2545kV/cm外加电场下,噪声模型和实验数据吻合;噪声随着外加电场和温度的增加而增加,当温度小于80K时噪声增加迅速,而当温度大于80K时噪声增加缓慢,并且温度越低噪声随外加电场变化越明显;噪声不随微米尺度电子传输激发能的变化而变化,随着纳米尺度电子传输激发能的增加而减小,随着纳米尺度电子传输激发能变化速度的增加而增加.该研究可为量子点红外探测器的优化设计和性能提高提供理论参考.     

晶振加速度敏感性矢量计算及耦合机理研究

针对晶振减振降噪设计的应用需求,从理论上阐述了振动敏感性研究的必要性,确定了一种适用于工程需要的定义、表征和测量方法,从数据挖掘的角度研究了各种输入条件对晶振电气性能的影响。并编制了相应的算法来进行求解,搭建了晶振相位噪声测试系统,发现了一些新现象,最终通过晶振振动实验验证算法的合理性。     

一种新型自适应模型预测组合滤波在在线标定中的应用

为了提高捷联惯性导航系统在线标定的精度和实时性,根据模型预测滤波算法和Sage_Husa自适应卡尔曼滤波算法的优点,提出了一种新的自适应模型预测组合滤波算法。该算法首先利用模型预测滤波算法估计出系统模型误差,并对系统状态方程实时修正,以减小系统模型误差对导航精度的影响;然后利用简化的自适应滤波算法对量测噪声在线调整,修正噪声统计特性,以提高滤波精度。将提出的算法进行在线标定仿真实验,并与传统的卡尔曼滤波在线标定算法进行比较,结果表明,提出的自适应模型预测组合滤波算法能有效完成在线标定,且标定精度和收敛速度均优于传统方法。     

简支梁非线性响应的三维路径积分法分析

采用基于Gauss-Legendre积分公式的三维路径积分法，分析了在过滤高斯白噪声激励下的简支梁非线性随机振动响应的概率密度函数；联立一阶滤波方程与简支梁一阶模态的振动模型，得到在过滤高斯白噪声激励下的简支梁随机振动模型，基于Gauss-Legendre积分公式的积分法和短时高斯近似法求解响应的概率密度函数值。结果表明，三维路径积分法计算值与蒙特卡洛模拟值符合良好，即使在尾部区域也符合良好。三维路径积分法比等效线性化法的计算精度更高。     

Spectrum warping based on sub-glottal resonances in speaker-independent speech recognition

To reduce degradation in speech recognition due to varied characteristics of different speakers,a method of perceptual frequency warping based on subglottal resonances for speaker normalization is proposed.The warping factor is extracted from the second subglottal resonance using acoustic coupling between subglottis and vocal tract.The second subglottal resonance is independent of the speech content,which reflects the speaker characteristics more than the third formant.The perceptual minimum variation distortionless response(PMVDR) coefficient is normalized,which is more robust and has better anti-noise capability than MFCC. The normalized coefficients are used in the speech-mode training and speech recognition.Experiments show that the word error rate,as compared with MFCC and the spectrum warping by the third formant,decreases by 4%and 3%respectively in clean speech recognition,and by 9%and 5%respectively in a noisy environment.The results indicate that the proposed method can improve the word recognition accuracy in a speaker-independent recognition system.     

谐振式硅基二氧化硅集成光学陀螺的克尔噪声研究

分析了集成光学谐振式陀螺中克尔噪声的产生机理,利用导波光学理论建立了克尔噪声的数学模型,并基于此模型得出了克尔噪声对集成光学陀螺极限灵敏度影响的数学表达.分析了不同光源谱宽下谐振腔腔长与克尔噪声引起陀螺输出偏移之间的关系;针对集成光学陀螺中克尔噪声的主要产生原因-谐振腔中顺、逆时针的光强不均衡,仿真分析了系统中集成光学...     

Comparative studies of silicon photomultipliers and traditional vacuum photomultiplier tubes

Silicon photomultipliers (SiPMs) are a new generation of semiconductor-based photon counting devices with the merits of low weight, low power consumption and low voltage operation, promising to meet the needs of space particle physics experiments. In this paper, comparative studies of SiPMs and traditional vacuum photomultiplier tubes (PMTs) have been performed regarding the basic properties of dark currents, dark counts and excess noise factors. The intrinsic optical crosstalk effect of SiPMs was evaluated.     

Simulation and measurement of the resonant Schottky pickup

A resonant Schottky pickup with high sensitivity, built by GSI, will be used for nuclear mass and lifetime measurement at CSRe. The basic concepts of Schottky noise signals, a brief introduction of the geometry of the detector, the transient response of the detector, and MAFIA simulated and perturbation measured results of characteristics are presented in this paper. The resonant frequency of the pickup is about 243 MHz and can be slightly changed at a range of 3 MHz. The unloaded quality factor is about 1072 and the shunt impedance is 76 kΩ. The measured results of the characteristics are in agreement with the MAFIA simulations.