数字化声学测量技术──Ⅰ.概论

数字化是当今世界上声学测量技术的发展趋势，它采用微计算机和数字信号处理系统．数字化声学测量的主要优点是：1．精确度高，动态范围大2．性能稳定，可靠3．可实现许多模拟仪器设备不能完成的复杂功能4．使用灵活方便5．优异的性能价格比．本文综合介绍了数字化声学测量技术的这些优越性，同时还介绍了一种实际使用的数字化声学测量系统的组成和工作原理，以及它的主要测量分析功能．本文可为涉及声学测量的部门和单位在选择仪器设备时提供参考．     

A beam interpolation algorithm in digital multi-beam sonar

I.IntroductionThedigita1operationins0narsystembringsagreatadvantageinbeamforming.Itispos-sib1etorealizesomcalg0rithmsindigita1technique,whichisusua11yhardtoorimpossib1etoAnp1ementintraditiona1ana1ogues0nar.Asanexamp1e,ageometrygraphofcirclearrayisil-1ustratedinFig,1.Thetotalnumber0farraye1ementisN.Therearetwokindsofbeam.TheA-c1assbeamconsistsof2M-le1ements,thesteeringdirectionisjustlocatedintheposi-honofoneofthearrayelement;TheB-classbeamconsistsof2Me1ementsandthesteeringdirectionisinthem…     

The study of fractal correlation method in the displacement measurement and its application

The classical digital speckle, or digital image, correlation method of deformation measurement is based on gray level correlation between unformed and deformed digital images. The pattern of artificial random speckles and the natural textures on some object's surfaces have fractal characteristics, and their fractal dimensions represent both gray and morph information. Furthermore, the fractal dimensions are stable feature parameters of the patterns. The digitized images of the patterns are confirmed to be also fractals. By this fact, a new method of displacement measurement is developed in the paper, based on the fractal dimensions correlation. The in-plane displacement fields of a body can be acquired. In order to verify the validity of the new method, an experiment has been designed and the results have been compared with those obtained from the classical digital image correlation method. The validity of the new method is not less than that of classical method. Further discussions about the traits and the developing vista of the method are given at the end.     

光互连Omega网络与全交叉网络拓扑等价的多样性

本文对互连网络拓朴等价的分析方法作了简单评述,并采用互连网络拓朴等价的图分析法分析了自由空间光学互连Omega网络与全交叉网络的拓朴等价及其多样性,拓展了Omega网络在通信交换、数字光计算以及并行多处理机系统的潜在应用。     

关于一类非连续的正交函数及其应用的探讨

本文研究一类新的非连续分段线性函数系,它是正交且完备的。特别讨论了它与离散斜变换的内在联系,从而建立直接的快速算法。分析表明这些结果有希望作为数字信号处理某些问题的新的有效的数学工具。     

Hybrid investigation on residual stresses induced by self-drilling screw on polycarbonate plates

The residual stresses induced by using self-drilling screws on polycarbonate plates were investigated by the hybrid method which incorporates the digital photoelastic method and finite element method (FEM). Different types of screws lead to different photoelastic fringe patterns, which provide the boundary conditions needed in the numerical simulation. By changing the two main parameters (pressure and temperature), the FEM results can be matched well with the experimental results for drilling at 0° tilt angle. For drilling at other tilt angles, the photoelastic fringe patterns provide useful information for failure analysis.     

A copyright protection watermarking algorithm for remote sensing image based on binary image watermark

As the internet keeping developing, copyright protection of the remote sensing image has become more and more important. This paper designs the algorithm that protects remote sensing image's copyright by using the binary digital watermark technology, and analyzes security and imperceptibility of the algorithm. As the experiment result shows, the algorithm put forward in this paper has better security, imperceptibility and anti-attack robustness, and thus it can meet the requirements in protecting copyright of the digital remote sensing image in an effective manner.     

物体的三维形状或离面变形的自动检测技术

本文采用数字图象处理设备,应用一维傅立叶变换技术和分段线性增强技术,提出了一种建立投影云纹数字图象的新方法,所形成的条纹图象灰度具有严格的正弦或余弦分布特性,结合位相检测技术,可计算出物体的离面高度或离面变形。可完全由计算机进行处理,自动化程度高,并能保证测量精度.最后给出了应用于物体形状检测或离面变形测试的两个实例,实验结果表明了该方法的可行性和可靠性。     

Mechanistic – Kinetic Scheme of Oxidation/Reduction of TEMPO Involving Hydrogen Bonded Dimer. RDE Probe for Availability of Protons in Reaction Environment

Mechanistic – kinetic studies on the electrochemical oxidation/reduction process of radical TEMPO (2,2,6,6‐tetramethylpiperidine‐1‐oxyl) under ionic strength (0.1 M, 1.0 M) and pH (0, 7) of aqueous perchlorate electrolyte (NaClO₄‐HClO₄) have been undertaken. Analytical and/or digital simulation methods for voltammetry at stationary (CV) and rotating electrode (RDE) have allowed one to determine numerical values of twelve parameters characterizing two electrode reactions (oxidation and reduction of the radical) and three chemical reactions (protonation, disproportionation, dimerization involving the radical and/or electrogenerated species). A potential window of the measurements was 0.6 V and it corresponded to that where the oxidation wave of TEMPO in neutral aqueous solution is situated. To account for the observed pH effect, the hydrogen bonded dimer resulting from the radical reactant and the protonation product of its reduction has been postulated to form in solution near the electrode surface. The RDE voltammetric discernables of the TEMPO process (i.e., absolute RDE wave current, zero RDE current potential, oxidation and reduction limiting RDE currents) can be considered good candidates for a use to follow acidity of complex reactive media.     

Evaluation of selectivity and robustness of near-infrared glucose measurements based on short-scan Fourier transform infrared interferograms

The selectivity and robustness of near-infrared (near-IR) calibration models based on short-scan Fourier transform (FT) infrared interferogram data are explored. The calibration methodology used in this work employs bandpass digital filters to reduce the frequency content of the interferogram data, followed by the use of partial least-squares (PLS) regression to build calibration models with the filtered interferogram signals. Combination region near-IR interferogram data are employed corresponding to physiological levels of glucose in an aqueous matrix containing variable levels of alanine, sodium ascorbate, sodium lactate, urea, and triacetin. A randomized design procedure is used to minimize correlations between the component concentrations and between the concentration of glucose and water. Because of the severe spectral overlap of the components, this sample matrix provides an excellent test of the ability of the calibration methodology to extract the glucose signature from the interferogram data. The robustness of the analysis is also studied by applying the calibration models to data collected outside of the time span of the data used to compute the models. A calibration model based on 52 samples collected over 4 days and employing two digital filters produces a standard error of calibration (SEC) of 0.36 mM glucose. The corresponding standard errors of prediction (SEP) for data collected on the 5th (18 samples) and 7th (10 samples) day are 0.42 and 0.48 mM, respectively. The interferogram segment used for the analysis contained only 155 points. These results are compatible with those obtained in a conventional analysis of absorbance spectra and serve to validate the viability of the interferogram-based calibration.