基于光源调制技术的金标试纸条定量分析仪器

基于光电检测原理,研发了一套可用于金标免疫试纸条定量检测的分析仪器。采用绿光发光二极管(LED)作为发射光源,以光电二极管接收试纸条反射光,并通过步进电机带动检测系统扫描试纸条待检区域。系统采用光源信号的调制与接收信号的解调技术,以消除环境干扰噪声。实验结果表明,该仪器检测结果准确,与真实值之间误差<1%;稳定性高,变异系数CV<2%。     

Contactless hybrid sensor for simultaneous detection of light reflectance and eddy currents

We demonstrate a contactless hybrid sensor for the simultaneous detection of light reflectance and eddy currents. The sensor is based on combining an optical system with an RLC self-resonator, wherein the reflected light intensity and resonance frequency are measured. We demonstrate that the hybrid sensor can be used for monitoring metals coated with non-metallic films. Whereas the self-resonator can efficiently distinguish between metals and non-metals, the optical subsystem is sensitive to changes in the reflectance of light. A systematic investigation of the detector response as a function of distance to the material under test is undertaken to characterize its behavior.     

Classification of human brain tumours from MRS data using Discrete Wavelet Transform and Bayesian Neural Networks

The diagnosis of brain tumours is an extremely sensitive and complex clinical task that must rely upon information gathered through non-invasive techniques. One such technique is Magnetic Resonance Spectroscopy. In this task, radiology experts are likely to benefit from the support of computer-based systems built around robust classification processes. In this paper, a Discrete Wavelet Transform procedure was applied to the pre-processing of spectra corresponding to several brain tumour pathologies. This procedure does not alleviate the high dimensionality of the data by itself. For this reason, dimensionality reduction was subsequently implemented using Moving Window with Variance Analysis for feature selection or Principal Component Analysis for feature extraction. The combined method yielded very encouraging results in terms of diagnostic discriminatory binary classification using Bayesian Neural Networks. In most cases, the classification accuracy improved on previously reported results.     

基于粒子群优化算法的LFM信号参数估计

在相同时宽范围内,恒定能量的线性调频信号频谱幅度平方与调频斜率呈反比。基于该特性,将信号解调后幅度平方最大值对应的参考信号调频斜率作为其估计值,进而估计其他参数。但该参数估计算法存在高估计精度与大运算量之间的矛盾,为此,将粒子群优化算法引入信号参数的搜索估计过程中。对搜索区间进行高精度划分以提高参数估计的精度,逐步改变参数值,并利用粒子群优化寻找解调后信号幅度平方的最大值,从而估计出相应参数。仿真实验结果证明,该算法运算量较少,且具有更高的估计精度。     

电力线载波通信技术在楼宇智能监控中的应用

介绍了一种基于电力线载波的楼宇智能控制系统的实现方法。其以LM567为核心，通过调制发送和解调接收，在电力线上实现了语音信号和控制信号的复用传输。     

Resonance properties and mass sensitivity of monolithic microcantilever sensors actuated by piezoelectric PZT thick film

The PZT thick film cantilever devices fabricated via MEMS process have much attraction because they are appropriate for biological transducer or sensor, resulting from their large actuating force and relatively high sensitivity especially in liquid. By means of resonance behavior, theoretical calculation and experimental verification of the PZT thick film cantilever devices have not been studied before. Accordingly, we focused on the sensitivity analysis and interpretation of the PZT thick film cantilevers in this study. Especially, the investigation for mass sensitivity of the PZT thick film cantilever is of importance for physical, chemical and biological sensing application. The PZT thick film cantilever devices were constructed on Pt/TiO₂/SiN _X /Si substrates using screen printing method and MEMS process. The harmonic oscillation response (resonance frequency) was measured using an optical laser interferometric vibrometer. The effect of cantilever geometry on the resonance frequency change was investigated. Compared with the theoretical resonant frequency change by mass loading, the experimental resonant frequency change of the PZT micromechanical thick film cantilever shows a variation of less than 2%. Mass sensitivities are estimated to be 30.7, 57.1 and 152.0 pg/Hz for the 400 × 380 μm, 400 × 480 μm and 400 × 580 μm cantilever, respectively.     

光纤光栅传感器信号解调方法综述

当光纤光栅传感器上的温度或应力发生变化时,布拉格反射波长也随之发生漂移,根据这个漂移量便可判断待测量大小,因此,人们提出了许多解调方法.文章论述了几种常用的光纤光栅传感器信号解调方法,分类评述了这几种方法的工作原理和性能,分别给出了其典型的实验原理图,并对其优点和缺点进行了分析比较.     

基于最小二乘法的光纤光栅Bragg波长直线拟合

针对基于可调谐法布里珀罗(F-P)滤波器的光纤光栅解调系统存在波长解调准确度不够高的问题,从理论上系统地分析了在解调过程中对光纤光栅B ragg波长进行直线拟合的可行性,即光纤光栅B ragg波长与F-P滤波器的调谐电压之间存在线性相关性。在实验研究的基础上,用最小二乘法对光纤光栅B ragg波长和F-P滤波器的调谐电压进行直线拟合,结果表明:它们之间的确存在密切的线性相关性。为提高拟合的效果,提出了分段直线拟合,它可以使测量误差降低至少1个数量级,从而提高了F-P滤波器光纤光栅解调系统的准确度。     

数字调幅广播系统中包络检波方法的研究

介绍了数字调幅广播的检波方法,给出了两种实现检波的实际算法:FFT和DCT,重点论述了两种算法的原理以及在实现数字广播包络检波过程中的工作原理。最后利用MATLAB对这两种方法进行了性能仿真并比较了两种检波方法的误码率。     

基于线阵图像传感器的光纤光栅传感解调技术

对比线阵CCD，CMOS图像传感器和InGaAs图像传感器的原理、特点和性能，提出了基于InGaAs图像传感器的光纤光栅传感解调技术，并设计了基于线阵InGaAs图像传感器的光纤光栅传感解调系统，而且通过计算机控制单独对应力和温度变化进行了测量实验，得到了理想的结果．基于线阵InGaAs图像传感器的解调系统不但测量精度和分辨率很高，而且基本上实现了光纤光栅传感的智能化，为光纤光栅传感的工业化奠定了基础，具有很好的应用前景.