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Application of Discrete Cross-Correlation Function for Observational-Comparative Navigation System

Abstract

The article presents navigation system project operating on the principle scene matching area correlation (SMAC), using a digital camera, an MEMS e-compass sensor and an ultrasonic ranging module. Systems of this type are used as a component of advanced integrated navigation systems in view of its autonomy and capability of localizing aircrafts with high accuracy and precision. Steering and display of information are implemented using a computer application designed in Matlab programming environment. The object’s location is fixed, using discrete cross-correlation function through matching of the registered terrain image to digital orthophotomap.

The article describes operations directly related to digital image processing, its implementation methods, a structural system design with explanations of each of the functional elements and presents devices used to build a complete integrated measurement unit model. It was used for the effectiveness measurement of determining the location of an object depending on the changes of angle and height of the flight as well as the luminance and noise level in a registered image. The measurements methodology was described which also includes an analysis of the results, an effectiveness evaluation and potential development directions of the designed system.

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Cross-Correlation-Based Method vs. Classical Fft for Spectral Analysis of Impulse Response

Abstract

The paper presents comparison of results of impulse response spectral analysis that has been obtained using a method based on cross-correlation with results obtained using classical FFT. The presented non-Fourier method is achieved by correlating the analyzed signal and reference single-harmonic signals and using Hilbert transform to obtain an envelope of cross-correlation. The envelope of crosscorrelation makes it possible to calculate appropriate indicator and make its plot in frequency domain as a spectrum. The spectrum obtained this way has its advantage over the FFT that the spectral resolution does not depend on duration of signal. At the same time, the spectral resolution can be much greater than spectral resolution resultant from FFT. Obtained results show that presented non-Fourier method gives frequency readout more accurate in comparison to FFT when the impulse response is a short-time signal e.g. few dozen of miliseconds lasting.

Open access
Application of conditional averaging to time delay estimation of random signals

in the measurement of particle-laden flows. Powder Technology, 318, 491-500. [11] Mosorov, V. (2008). Flow pattern tracing for mass flow rate measurement in pneumatic conveying using twin plane electrical capacitance tomography. Particle & Particle Systems Characterization, 25 (3), 259-265. [12] Zhang, L., Wu, X. (2006). On the application of cross correlation function to subsample discrete time delay estimation. Digital Signal Processing, 16, 682-694. [13] Beck, M.S., Pląskowski, A. (1987). Cross-Correlation

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Pneumatic Flow Characterization Using ECT Tomography Images Analysis

References [1] Beck, M. S. (1981). Correlation in instruments: cross correlation flowmeters. Journal of Physics E: Scientific Instruments 14(1), 7 [2] Chen, C., Wo&zacutelniak, P. W., Romanowski, A., Obaid, M., Jaworski, T., Kucharski, J., Grudzień, K., Zhao, S. and Fjeld, M. (2016). Using crowdsourcing for scientific analysis of industrial tomographic images. ACM Trans. Intell. Syst. Technol. 7(4), 52:1–52:25 [3] Datta, U., Dyakowski, T. and Mylvaganam, S. (2007). Estimation of particulate velocity components in pneumatic transport using

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Harmonic and pulsed eddy current testing methods as tools for surface and subsurface defect evaluation

Abstract

In most publications eddy current testing (ECT) methods are said to be suitable for surface defects up to several millimeters. This paper aims to evaluate the detection capabilities of eddy current testing based on two examples of modern approach. One of them is a harmonic eddy current method with use of wavelet transformation and neural network. The second method is pulsed eddy current testing (PECT) with use of evaluation script based on cross-correlation of measured data with the set of known reference signals. Two samples with five artificial defects each were investigated from the near and far side. Geometric parameters of every defect were then estimated. Results show that both methods are limited by the skin effect. However, the PECT with use of cross-correlation exhibits detection capabilities of subsurface defects in significant depth. On the other hand, harmonic eddy current testing shows lower errors in dimensions estimation for set of surface defects.

Open access
Pseudorange error analysis for precise indoor positioning system

Abstract

There is a currently developed system of a transmitter indoor localization intended for fire fighters or members of rescue corps. In this system the transmitter of an ultra-wideband orthogonal frequency-division multiplexing signal position is determined by the time difference of arrival method. The position measurement accuracy highly depends on the directpath signal time of arrival estimation accuracy which is degraded by severe multipath in complicated environments such as buildings. The aim of this article is to assess errors in the direct-path signal time of arrival determination caused by multipath signal propagation and noise. Two methods of the direct-path signal time of arrival estimation are compared here: the cross correlation method and the spectral estimation method.

Open access
Effective Exchange Rates in Central and Eastern European Countries: Cyclicality and Relationship with Macroeconomic Fundamentals

Abstract

This paper examines the evolution of effective exchange rates in nine Central and Eastern European countries in terms of development trends, volatility and cyclicality. Consequently, it provides direct empirical evidence on the nature of the relationship between effective exchange rates and selected macroeconomic fundamentals, addressing a key precondition of numerous exchange rate determination models and theories that attempt to explain the role of exchange rates in the economy. The results suggest that flexible exchange rate arrangements are reflected in both nominal and real effective exchange rates having higher volatility and variability. Furthermore, the results provide mixed evidence in terms of intensity, direction and cyclicality, but show a weak correlation between exchange rates and fundamentals. Sufficiently high coefficients are found only for money supply. Consequently, using fundamentals for the determination of exchange rates and using the exchange rate to explain economic development may be of limited use for the countries analyzed.

Open access
A Novel Three-Head Ultrasonic System for Distance Measurements Based on the Correlation Method

Abstract

A novel double-emitter ultrasonic system for distance measurements based on the correlation method is presented. The proposed distance measurement method may be particularly useful in difficult conditions, e.g. for media parameters undergoing fast changes or in cases when obstacles and mechanical interference produce false reflections. The system is a development of a previously studied single-head idea. The present article covers a comparison of the two systems in terms of efficiency and precision. Experimental research described in this paper indicated that adding the second head improved the measurement exactness – standard deviation decreased by 40%. The correlation method is also described in detail, also giving the criterion for the quality of the measurement signal.

Open access
On the interpretation of seismic cone penetration test (SCPT) results

References [1] AREIAS L., Van IMPE W., Interpretation of SCPT Data Using Cross-over and Cross-Correlation Methods, Engineering Geology for Infrastructure Planning in Europe, Springer, 2004. [2] BAGIŃSKA I., Analiza oceny rodzaju gruntu ustalonego na podstawie badań CPTU, Geoinżynieria, Drogi, Mosty, Tunele, 2012, nr 2, 38-45. [3] BAJDA M., Źródło generacji fali sejsmicznej w sondowaniach SCPT, Przegląd Naukowy Wydziału Inżynierii i Kształtowania Środowiska, 2009, No. 4 (46), 57-66. [4] FAJKLEWICZ

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Computationally Efficient Chaotic Spreading Sequence Selection for Asynchronous DS-CDMA

. https://doi.org/10.1109/tcsi.2002.804545 [6] A. Litvinenko and A. Aboltins, “Use of cross-correlation minimization for performance enhancement of chaotic spreading sequence based asynchronous DS-CDMA system,” in 2016 IEEE 4th Workshop on Advances in Information, Electronic and Electrical Engineering (AIEEE) , 2016, pp. 1–6. https://doi.org/10.1109/aieee.2016.7821812 [7] J. Jie Yang, M. H. Moon Ho Lee, and M. Mingqi Jiang, “Optimal over sampled chaotic map binary sequences for CDMA,” in 2002 IEEE International Symposium on Circuits and Systems

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