新一代运载火箭时序仿真系统信号完整性分析

新一代运载火箭时序仿真系统具有数字电路速度快、集成度高的特点,系统要求发出多路高精度时序、时串信号以满足新一代运载火箭地面测试设备的检查与校准需求,因此信号完整性问题在系统设计中不容忽视。针对仿真系统的典型模块(USB 3.0 Super-speed差分线、FPGA外设数据走线、时钟走线)进行建模分析仿真得出PCB硬件电路设计参数,给出时序仿真系统设计信号完整性问题的抑制和解决方法,优化了板级信号质量,改善系统可靠性、工作连续性和输出精度,可有效提高新一代运载火箭测试效率和测试可靠性。     

一种新型多功能信号源系统的设计

为适应航天领域遥测外系统的快速发展,提出了一种新型多功能信号源系统的设计。系统以FPGA为逻辑控制单元,采用PCI总线接口实现了与上位机的通信,同时结合AD5628、AQY210及RS422接口芯片稳定地输出了多路模拟信号、开关信号及一路PCM信号。重点阐述了信号源系统硬件及软件设计中的关键技术。试验结果表明,该系统能够提供多种高精度、高可靠性的信号,且工作性能稳定,抗干扰能力强,数据传输速率达到40Mbps,PCM码率高达983.04kbps,满足了系统设计的要求。     

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。     

Scale-space point spread function based framework to boost infrared target detection algorithms

Small target detection is one of the major concern in the development of infrared surveillance systems. Detection algorithms based on Gaussian target modeling have attracted most attention from researchers in this field. However, the lack of accurate target modeling limits the performance of this type of infrared small target detection algorithms. In this paper, signal to clutter ratio (SCR) improvement mechanism based on the matched filter is described in detail and effect of Point Spread Function (PSF) on the intensity and spatial distribution of the target pixels is clarified comprehensively. In the following, a new parametric model for small infrared targets is developed based on the PSF of imaging system which can be considered as a matched filter. Based on this model, a new framework to boost model-based infrared target detection algorithms is presented. In order to show the performance of this new framework, the proposed model is adopted in Laplacian scale-space algorithms which is a well-known algorithm in the small infrared target detection field. Simulation results show that the proposed framework has better detection performance in comparison with the Gaussian one and improves the overall performance of IRST system. By analyzing the performance of the proposed algorithm based on this new framework in a quantitative manner, this new framework shows at least 20% improvement in the output SCR values in comparison with Laplacian of Gaussian (LoG) algorithm.     

Poly‐ε‐Lysine Modified Nanocarbon Film Electrodes for LPS Detection

We developed an electrochemical system for detecting lipopolysaccharide (LPS) that uses an ultraflat nanocarbon film electrode modified with poly‐ε‐lysine with a high affinity to LPS. LPS was captured on the modified electrode, and then ferrocene labeled polymyxin B (FcPMB) was captured on the LPS adsorbed electrode via the LPS‐PMB affinity interaction. The adsorbed FcPMB provided an amplified response with Fe²⁺ ions, and the current response was dependent on the amount of captured LPS (LOD=2.0 ng/mL). This was due to the efficient accumulation of the obtained current for LPS and the very low noise made possible by the ultraflat surface.     

Nanostructures of noble metals as functional materials in biosensors

Recent advancement in nanoscience and nanotechnologies inspired a wide spectrum of uses of nanodimensional materials ranging from industrial sector to biomedical applications. Inorganic nanomaterials made of noble metals, which are corrosion-resistant, are often included as electrode modifiers in designing electrochemical chemosensors and biosensors because of their unique catalytic, electric, and surface-related properties. This review summarizes the developments in electrochemical biosensors with integrated in their architecture metal nanostructures reported mainly during the last two years with a summary on some of the commonly used methods for the synthesis of metallic nanostructures. Nanodimensional noble metal structures might be considered as multipurpose electrode modifiers because of their abilities to act at the same time as electrocatalysts, signal amplifiers, and tools for immobilization and spatial orientation of redox proteins/enzymes or other type of bioreceptors.     

互相关法在光纤液滴指纹图分析中的应用

为了实现光纤液滴指纹图的实时分析,引进了互相关分析法.在对乙醇溶液测量的过程中,将50％浓度的乙醇溶液对应的光纤液滴指纹图作为参考指纹图,然后将测得的光纤液滴指纹图与参考指纹图进行互相关,得到光纤液滴指纹图的相关曲线,从中提取与液体参量有关的各种信息.利用互相关分析法对各种浓度的乙醇溶液进行了处理,得出了相关峰高度与浓度的单调关系,验证了互相关法的可行性.     

Disentangling stochastic signals superposed on short localized oscillations

We introduce a procedure for separating periodic oscillations superposed on a stochastic signal. The procedure combines empirical mode decomposition (EMD) of a signal with tools of data analysis based on stochastic differential equations, namely nonlinear Langevin equations. Taking the set of modes retrieved from the EMD of the signal, our procedure is able to separate them into two groups, one composing the periodic signal and another composing the stochastic signal. The framework is robust for a broad family of localized oscillations, in the range of large frequencies. In particular, we show that, in this context, the EMD method outperforms a low-pass filter and is robust for a wide interval of different frequency ranges and amplitudes of the periodic oscillation, as well as for a broad family of different non-linear Langevin processes.     

基于EEMD-MRA方法的LIBS信号处理研究

LIBS技术优点众多,但由于光谱噪声干扰和基体效应等因素,影响了分析的准确度^[1]; EEMD方法能清晰的将LIBS信号中的不同特征成分自适应的分解开来。MRA方法能够补偿元素信号之间的互干扰,可进一步提高LIBS信号的准确性。通过自行搭建的测试系统获得了标准样品的原始信号,使用EEMD-MRA方法进行处理后,元素浓度曲线的决定系数R²得到了极大的提高,大大的提高数据的准确性,为LIBS信号的处理提供了一种全新的方式。     

基于经验模态分解的SO_2浓度检测信号处理方法

荧光法测量SO2浓度是大气监测中常用的检测手段.双光路技术可以消除光源和光路的噪音干扰,但光电转换器件在激发光照射下产生的背景噪音也会影响定量分析的准确度.本文采用经验模态分解滤波算法降低检测中存在的各种噪音,在实现有效降噪的基础上较好地保存了有用的原始信号.仿真结果表明,针对SO2浓度检测系统,利用经验模态分解去噪后信号的信噪比达到204.273 6,均方误差为0.007 0.与小波去噪法相比,经验模态分解检测效果更佳.最后将经两组不同方法处理后的信号应用于气体检测系统中,实验数据的线性关系更好地验证了经验模态分解方法应用到浓度检测系统的可行性.