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OALib Journal期刊

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APPLICATION OF SYNTHETIC INSTRUMENTATION THAT APPLIES THE TREND OF SOFTWARE-BASED APPROACH FOR MEASURING ON THE FIELD OF MODERN WIRELESS TRANSFER SYSTEMS
Radek Martinek,Jan Zidek
International Journal of Digital Information and Wireless Communications , 2012,
Abstract: This paper describes modern software based flexible measuring systems for analysis of digitally modulated systems. The latest methods for evaluation of modulation parameters using new generation test systems based on PXI modular platform and graphical programming in LabVIEW are demonstrated. Authors concentrate on the most widely used modulation technique used in radio communication systems - QPSK. On the real measurement of the QPSK modulation parameters, authors attempt to make the readers acquainted with not very widespread synthetic measuring instruments in the application area of wireless transfer systems. The basic idea of functionality of these instruments comes from the definition of the software radio. Experiments themselves demonstrate the fundamental differences in the conception of traditional and synthetic instrumentation. The focus is mainly on the different understanding of the key component in the form of software and hardware for both investigated platforms.
The Real Implementation of NLMS Channel Equalizer into the System of Software Defined Radio
Radek Martinek,Jan Zidek
Advances in Electrical and Electronic Engineering , 2012,
Abstract: This paper deals with modern wireless transmission systems. It focusses on real implementation of NLMS channel equalizer into the system of software defined radio. The authors aimed to conduct a real measurement (BER vs. Eb/No) using modern modular PXI measuring apparatus. This sophisticated measuring system is built by vector-signal generator RF VSG NI PXI-5670 and vector-signal analyzer RF VSA NI PXI-5660. The results of experiments suggest that the channel equalizer with implemented NLMS algorithm has better results (balance between simplicity and performance) than conventionally most used LMS algorithm. This holds true if feasible computational complexity with respect to real time processes is assumed.
Hybrid Power System Power Flow Analysis  [PDF]
Petr Bilik, Jakub Manas, Jan Zidek, Jiri Koziorek
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B135
Abstract:

Hybrid power supply system consists of a number of independent and different sources of electrical energy with different operating times during different seasons and with energy storage system. Deployment of a hybrid power system is expected in places outside the normal distribution network. For the further research and improvements it is necessary to know in detail the power flow from various sources to the load or to storage battery depending on different seasons. The paper presents data analysis results computed by application developed for detailed analysis of power flows within hybrid power system. Developed application analyses the data from the monitoring system. Data has been acquired and recorded within last year. This data is visualized as power flows in the individual hybrid power system circuits. Together with electrical power the effectiveness and performance parameters of rectifier and DC/AC converter are evaluated. The paper describes achieved results and needs for further improvements of such solution.

Harmonic Currents of Semiconductor Pulse Switching Converters  [PDF]
Petr Bilik, Jan Zidek, Vaclav Kus, Tereza Josefova
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B214
Abstract:

Due to the operation of power semiconductor switching converters, the content of harmonic currents, which these switching converters take from the feed array, is still increasing. One of the possible ways of minimizing these currents is the use of pulse switching converters. On one hand, the original, characteristic harmonic ones are minimized, but, on the other hand, new frequencies caused by the modulation frequency appear in the current spectrum. The level of the currents of these frequencies is small and is scarcely dependent on the load of the converter. It may happen that the proportional value of the monitored harmonic one is high, although the absolute value is low. In the article presented, there is a description of the activity of the pulse voltage rectifier and an analysis of the current taken. The other part contains the results of the harmonic analysis of the stated current, including both the absolute and proportional values according to the load. In the conclusion, there are results of measurements of pulsed switching converters taken from the real measurement.

BIT ERROR RATIO CONCEPT AND 3D EYE DIAGRAM TO ANALYSIS OF M STATE DIGITALLY MODULATED SIGNALS
Mohamed Al-Wohaishi,Jan Zidek
International Journal of Digital Information and Wireless Communications , 2011,
Abstract: When designing digital systems and incorporating a high-speed digital device with the need of quick transfer of large data amounts between chips and peripherals, jitter will be a key parameter to measure. In this paper, we are able to determine the initial phase of a carrier sine wave by performing carrier recovery loop in Digital communication systems of M-ary quadrature amplitude modulation (M-QAM) schemes. It is important for the M-ary QAM carrier recovery circuits to have low phase jitter as well as only four stable phase points as we see below. We examined the effect of channel noise on carrier recovery. More specifically, we examined what behaviour can occur when channel noise is significant enough to prevent carrier locking. We saw the symbols on the 3D Eye Diagram and constellation plot begin to jitter at first, and then settle closer to the ideal symbol locations after a short period of time. Authors of this article present real results, which illustrate the link between number of symbols in M-state QAM modulation, SNR and BER. Constellation diagrams of transmitted and received symbols (with superposition of noise) were presented in the article. Simple picture is transmitted through simulated radio channel to show the result of signal impairments. Modular PXI HW platform was used in connection with graphically oriented development environment. This combination of modular HW and flexible SW components allows changing the communication protocol, modulation scheme, frequency bandwidth and other parameters in a very simple way by changing the software part of the system.
The Use of LMS and RLS Adaptive Algorithms for an Adaptive Control Method of Active Power Filter  [PDF]
Radek Martinek, Jan Zidek, Petr Bilik, Jakub Manas, Jiri Koziorek, Zhaosheng Teng, He Wen
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B215
Abstract:

This paper deals with the adaptive control mechanism management meant for shunt active power filters (SAPF). Systems driven this way are designed to improve the quality of electric power (power quality) in industrial networks. The authors have focused on the implementation of two basic representatives of adaptive algorithms, first, the algorithm with a stochastic LMS (least mean square) gradient adaptation and then an algorithm with recursive RLS (recursive least square) optimal adaptation. The system examined by the authors can be used for non-linear loads for appliances with rapid fluctuations of the reactive and active power consumption. The proposed system adaptively reduces distortion, falls (dip) and changes in a supply voltage (flicker). Real signals for measurement were obtained at a sophisticated, three-phase experimental workplace. The results of executed experiments indicate that, with use of the certain adaptive algorithms, the examined AHC system shows very good dynamics, resulting in a much faster transition during the AHC connection-disconnection or during a change in harmonic load on the network. The actual experiments are evaluated from several points of view, mainly according to a time convergence (convergence time) and mistakes in a stable state error (steady state error) of the investigated adaptive algorithms and finally as a total harmonic distortion (THD). The article presents a comparison of the most frequently used adaptive algorithms.

Comment on Article by Ferreira and Gamerman
James V. Zidek
Statistics , 2015, DOI: 10.1214/15-BA944C
Abstract: Comment on Article by Ferreira and Gamerman [arXiv:1509.03410].
Selecting likelihood weights by cross-validation
Xiaogang Wang,James V. Zidek
Mathematics , 2005, DOI: 10.1214/009053604000001309
Abstract: The (relevance) weighted likelihood was introduced to formally embrace a variety of statistical procedures that trade bias for precision. Unlike its classical counterpart, the weighted likelihood combines all relevant information while inheriting many of its desirable features including good asymptotic properties. However, in order to be effective, the weights involved in its construction need to be judiciously chosen. Choosing those weights is the subject of this article in which we demonstrate the use of cross-validation. We prove the resulting weighted likelihood estimator (WLE) to be weakly consistent and asymptotically normal. An application to disease mapping data is demonstrated.
Recognition of Epileptiform Patterns in the Human Electroencephalogram Using Multi-Layer Perceptron
J. Magdolen,F. Zidek,V. Mokran
Radioengineering , 1995,
Abstract: Automatic detection of epileptiform patterns is highly desirable during continuous monitoring of patients with epilepsy. This paper describes an unconvential system for automatic off-line recognition of epileptic sharp transients in the human electroencephalogram (EEG), based on a standard neural network architecture - multi-layer perceptron (MLP), and implemented on a Silicon Graphics Indigo workstation. The system makes comprehensive use of wide spatial contextual information available on 12 channels of EEG and takes advantage of discrete dyadic wavelet transform (DDWT) for efficient parameterisation of EEG data. The EEG database consists of 12 patients, 7 of which are used in the process of training of MLP. The resulting MLP is presented with the testing data set consisting of all data vectors from all 12 patients, and is shown to be capable to recognise a wide variety of epileptic signals.
Predicting phenological events using event-history analysis
Song Cai,James V. Zidek,Nathaniel Newlands
Statistics , 2010,
Abstract: This paper presents an approach to phenology, one based on the use of a method developed by the authors for event history data. Of specific interest is the prediction of the so-called "bloom--date" of fruit trees in the agriculture industry and it is this application which we consider, although the method is much more broadly applicable. Our approach provides sensible estimate for a parameter that interests phenologists -- Tbase, the thresholding parameter in the definition of the growing degree days (GDD). Our analysis supports scientists' empirical finding: the timing of a phenological event of a prenniel crop is related the cumulative sum of GDDs. Our prediction of future bloom--dates are quite accurate, but the predictive uncertainty is high, possibly due to our crude climate model for predicting future temperature, the time-dependent covariate in our regression model for phenological events. We found that if we can manage to get accurate prediction of future temperature, our prediction of bloom--date is more accurate and the predictive uncertainty is much lower.
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