在轨光学遥感仪器探测灵敏度的建模分析与应用

在分析光学遥感仪器探测信息中主要噪音源的基础上,提出了一种改进空间结构函数分析的仪器探测灵敏度在轨评价方法,包括：基于多项式递推分解的整体噪音估计模型,以及减小系统误差及修正模数转换噪音影响等基本技术途径.仿真结果证实,该改进算法的噪音估计准确度优于传统的高斯估计和基于外推的结构函数分析方法.针对实际观测数据,在去除模数转换噪音影响后,仪器噪音等效温度差指标的在轨评价准确度可达±0.05 K.该评价方法已在FY-2D静止气象卫星在轨测试中得到成功应用.     

基于连续统快速傅里叶变换的红外光谱处理技术

为实现红外光谱对遥感地物准确的识别,消除高频噪声是光谱特征分析和提取的重要环节。利用光谱连续统处理方法,结合信号时域分析领域快速傅里叶变换提出了一种新的红外光谱滤波方法。该方法首先对红外光谱进行光谱连续统去除,利用快速傅里叶变换将去连续统后光谱转换到频域,设计低通滤波器滤除高频噪声,然后通过快速傅里叶反变换将频域信号转换到时域,最后对信号进行光谱连续统恢复,得到滤除噪声后的红外光谱信号。对比实验表明,连续统快速傅里叶滤波方法比常规的时域滤波方法有更好、更快的滤波效果,解决了传统快速傅里叶红外光谱滤波的吉布斯现象。该方法操作简便、运行速度快捷、滤波效果好,满足了红外光谱地物识别对光谱高质量的要求。     

Low dose measurement with thick gate oxide MOSFETs

The low dose limit and the accuracy of high sensitivity MOS ionizing radiation dosimeters fabricated at LAAS-CNRS are investigated.     

Assessment of environmental noise and its effect on neonates in a Neonatal Intensive Care Unit

A method for analyzing the influence of noise on newborns is proposed. The method consists of defining three different types of time interval (quiet, noisy and nursing) and, for each period, environmental noise levels, heart rate, mean arterial pressure and oxygen saturation is continuously measured. The statistical analysis of the influence of the equivalent noise level, rather than instantaneous noise level, on the behavior of the physiological variables is carried out. Great influence of noise is found by using this method, which is also easily translatable to other intensive care units as actual noise conditions are used in the investigation. Moreover, episodes of Bradycardia, Hypoxia and Hypertension are easily related to simultaneous direct nursing activity or a short but high enough noise event, suggesting that both sustained noisy environment and isolated peak noises lead to the alteration of the physiological variables.     

Time domain identification and ranking of noise sources in a pneumatic nail gun

This paper investigates the noise sources in a pneumatic nail gun. The study combines two complementary experimental approaches. The first uses simultaneous data observation, with sound, acceleration and air pressure signals simultaneously recorded in conjunction with a nail gun motion high speed video. This strategy allows the identification of the physical processes involved in the operation of the machine at different time instants, as well as the associated noise generation mechanisms. However, since multiple noise sources radiate at the same time, this observation technique is not sufficient for noise source identification and ranking. Thus, a second approach introduces a selective wrapping procedure, and the strategy assures a reliable classification of the noise sources. The investigation considers the following noise origins: the air exhaust, the machine body and the workpiece/worktable.     

Dependence of noise induced effects on state preparation in multiqubit systems

The perturbation of multiqubit systems by an external noise can induce various effects like decoherence, stochastic resonance and anti-resonance, and noise-shielding. We investigate how the appearance of these effects on disentanglement time depends on the initial preparation of the systems. We present results for 2-, 3- and 4-qubit chains in various arrangements and observe a clear dependence on the combination of initial geometry of the state space and the placement of noise. Finally, we see that temperature can play a constructive role for the control of these noise induced effects.     

一种在色噪声环境下的信号检测方法

为了抑制蛟龙号载人潜水器水声通信受母船色噪声干扰的影响,本文提出了一种统计匹配滤波器在色噪声环境下使用的新方法,它通过将接收信号映射到一个生成子空间中进行信号检测,可提高输出水声通信信号的信噪比。受客观条件限制,向阳红09船——蛟龙号载人潜水器的试验母船噪声环境比较恶劣,对水声通信产生了较强的干扰。如何在向阳红09船的这种强、色噪声环境下,提升水声同步信号的检测能力,对提高水声通信的可靠性是非常有帮助的。实际采集试验数据分析结果验证了该检测算法比传统匹配滤波器有更强的信号检测能力。     

光静态散射测试系统的研究与实现

随着科学技术的发展,对粒子的大小、浓度及其他特性的探测已经发展成为一个专门的研究领域和现代测量学中的一个重要分支,而光散射法已经成为一种常用的粒子测量方法。为了满足应用需求,文中提出了一种基于C8051F500单片机的光静态散射测试系统方案,详细介绍了该测试系统的设计理论原理、硬件电路的设计依据、固件程序的设计思想和测试系统的具体实现。选取一定浓度的样品溶液,运用该系统进行光散射的角度依赖性测试,实际测量值与理论依据基本相符;在不同激光功率下,对同一角度的散射光强进行测试,将测量得到的数据分析,线性度良好,满足设计要求。     

红外成像系统NETD参数测试算法及应用研究

噪声等效温差(NETD)是表征红外成像系统灵敏度的关键参数,也是评估红外成像系统性能的重要参数之一,应用广泛。通过对红外成像系统3D噪声、信号传递函数(SiTF)、NETD等参数测试方法、算法和流程研究,给出一种基于视频文件的3D噪声离线对比测试方法和一种SiTF线性区自动判断计算斜率算法,在此基础上针对某型技术保障装备国产化光电检测平台开发了配套应用软件功能模块。实现了通过计算单位均方根噪声所对应的SiTF斜率值,分析得出系统NETD参数值的功能。以某型热像仪为被测对象,开展了测试结果重复性和一致性试验,并与美国Optikos公司I-SITE红外整机测试系统进行了对比测试。实验结果表明开发的NETD参数测试功能模块测试精度和重复性满足设计要求,具有较高实用价值,已进行了工程应用。     

CORSICA: correction of structured noise in fMRI by automatic identification of ICA components

When applied to functional magnetic resonance imaging (fMRI) data, spatial independent component analysis (sICA), a data-driven technique that addresses the blind source separation problem, seems able to extract components specifically related to physiological noise and brain movements. These components should be removed from the data to achieve structured noise reduction and improve any subsequent detection and analysis of signal fluctuations related to neural activity. We propose a new automatic method called CORSICA (CORrection of Structured noise using spatial Independent Component Analysis) to identify the components related to physiological noise, using prior information on the spatial localization of the main physiological fluctuations in fMRI data. As opposed to existing spectral priors, which may be subject to aliasing effects for long-TR data sets (typically acquired with TR >1 s), such spatial priors can be applied to fMRI data, regardless of the TR of the acquisitions. By comparing the proposed automatic selection to a manual selection performed visually by a human operator, we first show that CORSICA is able to identify the noise-related components for long-TR data with a high sensitivity and a specificity of 1. On short-TR data sets, we validate that the proposed method of noise reduction allows a substantial improvement of the signal-to-noise ratio evaluated at the cardiac and respiratory frequencies, even in the gray matter, while preserving the main fluctuations related to neural activity.