声学多普勒流速剖面评价方法介绍与探讨

声学多普勒流速剖面仪是20世纪80年代初发展起来的一种新型测流设备,目前被广泛用于流速和流量测验。介绍了美国地质调查局(简称USGS)对声学多普勒流速剖面仪的评价方法,并探讨利用国内现有流速仪检定水槽评价多普勒流速剖面仪的方法。通过USGS的大量实践和我国水文工作者的工作,通过设备比测、底跟踪基线比测、断面流量比测、检定水槽等方法可有效评价声学多普勒流速剖面仪的流速性能。     

基于FPGA声学多普勒流速剖面仪的信号处理机设计

针对声学多普勒流速剖面仪的高速信号采集和处理对运算实时性与易升级的需求,提出一种基于现场可编程门阵列(FPGA)的软硬件协同设计方法。阐述声学多普勒剖面仪的测流原理,选择FPGA作为单一的信号处理器,使用Verilog HDL语言描述易于用硬件实现的模块,如同步采集、低通滤波及复数相关运算等计算量大的模块。采用FPGA内部的MicroBlaze软核作为系统的中央处理器,进行流程控制、分支判断以及调用硬件模块来控制系统回波信号的采集、处理和存储。实验结果表明,FPGA信号处理的实时性满足系统要求,且具有较高的精确性。     

声学多普勒流速仪自动测量和分析系统

文中针对声学多普勒流速仪单点测量中存在的几个问题，提出应用虚拟仪器技术实现声学多普勒流速仪的自动测量，并建立了声学多普勒流速仪自动测量和分析系统。该系统在提高了实验精度的同时，极大地缩短了工作周期，减少了工作量。将声学多普勒流速仪自动测量和分析系统应用于紊流边界层时均流速分布的测量，取得了较好的实验成果。     

单波束声学多普勒流速仪垂向在线测流应用研究

通过应用单波束垂向式声学多普勒流速仪(V-ADCP)进行在线流量测验,探索单波速V-ADCP的安装和流速数据处理计算方法。采用转子式流速仪对V-ADCP进行比测,分析V-ADCP采用相对水深某个区间范围内的单元流速计算垂线平均流速的方法,率定符合水文相关规范的V-ADCP测流的单断速关系,并确定单断速关系可生产应用的范围。通过对V-ADCP在线测流的应用,得到精度较高的单断关系,实现流量在线监测,可为进一步推广V-ADCP在线测流的应用进行探索。     

基于三次样条函数的数控插补算法研究

针对复杂轮廓的曲线,在数据采样插补原理的基础上,采用了一种基于三次样条函数的插补算法。该方法能精确地拟合出复杂曲线的轮廓,且使得该曲线具有很好的连续性。在基于ARM数控装置上,对此算法进行了实验验证,验证了该方法的可行性。     

声学多普勒流速快速测量的设计

传统的多普勒流速剖面测量仪将混频正交与低通滤波在软件中实现,存在测量时间长、精度不高等问题。为解决上述问题,采用运算速度更快、内存容量更大的STM32H743单片机作为主控芯片,同时设计了将信号混频、正交与FIR低通滤波在硬件电路中实现的多普勒流速剖面仪,这样大大减少了CPU的运算时间,提高了测量精度。运用FFT算法进行信号质量分析,利用自相关算法计算出各层流速。通过试验,对测得的多普勒频偏以及流速进行分析,结果表明,系统的设计满足在实际小型河流中的精确测量,具有可行性。     

基于遗传算法的三次样条函数拟合

介绍了遗传算法（ＧＡ）的一种新应用－三次样条函数拟合中的参数估计问题。三次样条函数拟合是曲线拟合的一个认的较好方法,它具有很好的分段光滑性,但三次样条函数拟合涉及到矩阵求逆,离散样本点越多,矩阵就越大,求逆就越繁琐。文中将用ＧＡ用于三次样条函数拟合的系数求解,避开了矩阵求逆的繁琐问题,结合具体例子作了一些探索。文中还对标准遗传算法进行了适当的改进,实验结果说明遗传算法是用于参数估计、优化的有力工具     

排水流量测量用声学多普勒流速仪设计及实现

由于城市排水管网流量测量面临淤积、油污、漂浮物、沼气等恶劣环境的考验,因此对流速仪的要求比明渠流量测量高。基于超声波对水中运动悬浮颗粒的多普勒效应,通过对超声换能器的特殊结构和阻抗匹配网络设计,提高超声换能器在同等发射功率下的作用距离,保证不同浊度场合的超声波作用范围。信号处理算法采用改良的选频傅立叶变换,有效提高频率分辨率,再配合相应的自适应滤波算法,保证在不同流态下的流量测量精度和稳定度。流速仪在检测中心的流速测试中,全量程范围内的流速线性度可达99.99%,校正后流速测量误差2%,满足绝大多数流量测量场合对于精度的要求。     

Fairing of Parametric Cubic B-spline Curves and Bicubic B-spline Surfaces

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Cubic spline interpolation based ultrasound scan conversion algorithm

Digital scan conversion is employed in medical ultrasound imaging system to display scanned vector data in Cartesian coordinate that are acquired with polar coordinate. Interpolation is applied to estimate gray values of unsampled pixels in digital scan conversion. A cubic spline interpolation based scan conversion algorithm is proposed for ultrasound vector data processing. Cubic spline interpolation is efficient to provide more accurate result images for both nature and ultrasonic images. Experimental results indicate that the result images of the proposed algorithm are more accurate than those of the nearest neighbor interpolation, linear interpolation and cubic convolution interpolation based algorithm.     

Cubic spline curve fitting with controlled end conditions

Several approximate methods for cubic spline curve fitting have been developed and successfully used. This paper presents a more flexible version of a proven technique by using a set of end conditions suggested by Nutbourne. The advantages and disadvantages of several techniques are clarified and sample graphical output is given. The results should be of greatest interest to users of inexpensive, computer graphics equipment who are interested in improving passive graphical output.     

Cubic spline approximation techniques for parameter estimation in distributed systems

Approximation schemes employing cubic splines in the context of a linear semigroup framework are developed for both parabolic and and hyperbolic second-order partial differential equation parameter estimation problems. Convergence results are established for problems with linear and nonlinear systems, and a summary of numerical experiments with the techniques proposed is given.     

导航随机微分模型的三次样条插值求解探索

提出一种用三次样条插值逼近导航系统状态概率密度函数的方法．导航随机微分模型的弱解由前向Kolmogorov方程表示,其解析解很难求得．本文通过三次样条插值函数来逼近其解可得到状态的先验概率密度函数,再由Bayes公式得到状态的后验概率密度函数,解决了构造三次样条插值条件的难点问题,并以水下潜器组合导航系统为背景,与粒子滤波方法进行性能对比分析,仿真结果验证了三次样条插值逼近导航随机微分模型解析解的可行性．     

肺功能仪数据采集与数据处理系统研究

本文用理论计算公式和实际曲线拟合两种方法对肺功能仪数据采集与数据处理进行研究。虽然两者都还有误差，但是实际曲线拟合效果好于理论公式计算，对于实际曲线拟合还有待于进一步改进。     

基于AIWCPSO算法的三次样条气动参数插值方法

针对飞行仿真建模过程中气动参数以矩阵的形式给出, 大都存在着非线性关系, 提出一种基于自适应惯性权重的混沌粒子群优化(AIWCPSO) 算法的三次样条气动参数插值方法. 首先建立粒子与三次样条插值函数中系数的映射关系; 然后利用AIWCPSO 算法对三次样条插值函数的系数进行寻优, 将获得的最优解近似看作三次样条插值函数的系数; 最后计算得到离散点的气动参数. 仿真实验结果表明, 所提出的方法能有效地解决飞行气动参数插值问题.     

Comparative analysis of function approximation methods applied to image processing

Application of nonlinear methods of multivariate regression approximation (neural networks, functions linear in fitting parameters, and hierarchical approximation) is considered to problems of image filtering based on a priori information in the form of matched pairs of images (“ideal” and “degraded”). The methods are compared with regard to their efficiency. Vasilii N. Kopenkov. Born 1978. Graduated from the Samara State Aerospace University (SSAU) in 2001. Assistant Professor at the Chair of Geoinformatics, SSAU, and a Junior Researcher at the Institute of Image Processing Systems, Russian Academy of Sciences. Scientific interests: image processing and pattern recognition. Author of four papers. Member of the Russian Federation Association for Pattern Recognition and Image Analysis. Andrei V. Chernov. Born 1975. Graduated from the Samara State Aerospace University (SSAU) in 1998. Received candidate’s degree (Cand. Sc. (Eng.)) in 2004. Assistant Professor at the Chair of Geoinformatics, SSAU, and a Researcher at the Institute of Image Processing Systems, Russian Academy of Sciences. Scientific interests: image processing, pattern recognition, and geoinformation systems. Author of more than 50 publications, including 11 papers in journals, and a co-author of a monograph. Member of the Russian Federation Association for Pattern Recognition and Image Analysis. Vladislav V. Sergeev. Born 1951. Graduated from the Kuibyshev Aviation Institute (now, the Samara State Aerospace University). Received doctoral degree (Dr. Sc. (Eng.)) in 1993. Head of Laboratory of Mathematical Methods of Image Processing, Institute of Image Processing Systems, Russian Academy of Sciences. Scientific interests: digital signal processing, image analysis, pattern recognition, and geoinformatics. Author of more than 150 publications, including about 40 papers in journals, and a co-author of 2 monographs. Chair of the Volga-region Branch of the Russian Federation Association for Pattern Recognition and Image Analysis. Corresponding Member of the Russian Ecological Academy and the Russian Academy of Engineering, member of SPIE (The International Society for Optical Engineering), a winner of the Samara District Award for Science and Engineering.