June 1999, Volume 8, Number 2
Switching sequential circuits are an indispensable part of many modern electronic devices, such as memory cells, flip-flop sensors, and many others. Since the invention of flip-flop switching circuits, the study of their dynamic behaviour has played an ever-increasing role. The dynamic properties of sequential circuits can be investigated by means of switching between the system's attractors. In this paper the boundary surfaces are discussed that play a crucial role in the process of switching.
In progressive image transmission (PIT) the image is transmitted progressively i.e. the low detail image is transmitted as first followed by transmission of detail signals. In our contribution we consider interactivity in the PIT. For example, the observer could specify image regions of highest interest (ROI). In this case, the image transmission should be optimised with respect to the ROI. The definition of objective criterion for interactive PIT is made in this paper as first. The spatial signal decomposition is derived with respect to this criterion. Wavelet transform of spatial components is used. At the end demonstration of proposed algorithm is made.
This paper presents the results of a study on the use of invertible rapid transform (IRT) for the motion estimation in a sequence of images. Motion estimation algorithms based on the analysis of the matrix of states (produced in the IRT calculation) are described. The new method was used experimentally to estimate crowd and traffic motion from the image data sequences captured at railway stations and at high ways in large cities. The motion vectors may be used to devise a polar plot (showing velocity magnitude and direction) for moving objects where the dominant motion tendency can be seen. The experimental results of comparison of the new motion estimation methods with other well known block matching methods (full search, 2D-log, method based on conventional (cross correlation (CC) function or phase correlation (PC) function) for application of crowd motion estimation are also presented.
This paper describes an educational application of distributed measurement systems for the tutored and self-educational process that has been designed and applied at the Department of Electronics and Multimedial Telecommunications, Technical University of Kosice for students at the senior level of their study. The main goal of this activity has been to improve and spread our students' knowledge beyond the traditional university education in the area of measurement and communications. The students involved do not only play a passive role in the usage of a ready-made distributed measurement system by executing a remote measurement but they have the opportunity to participate in the process of design, carrying out and supervising an own simple distributed measurement system. To simplify their task, they may either use the graphical programming environment LabVIEW or the standard ANSI C language based on the programming environment Labwindows/CVI with ready-made instrument drivers (GPIB, serial and plug-in multifunction boards) and basic software skeletons. The overview of the students' resources, task-solving steps and goals as well as the present results, experience and the expected future extensions are presented, too.
This paper is oriented to filtering by fuzzy stack filter of monochromatic images distorted with impulsive noise. Fuzzy stack filter is acquired by extension of stack filters by means of fuzzy logic. Adding some parameters to this filter, that are adjusted by neural adaptation algorithm, is obtained the new class of filters, so-called fuzzy rank-order filters. This class of filters is compared with other well known filters as stack filters and neural stack filters.
The most crucial issues in the conception of an efficient wireless ATM network are the design of the physical layer, data link layer. Medium Access Control (MAC) protocol and mobility management functions. In this article we focus on MAC protocols, namely on requirements for MAC protocols and on basic concepts of TDMA and CDMA based one. For illustration we consider with Time Division Duplex (TDD) as well as Frequency Division Duplex (FDD).
This contribution is devoted to the higher order time-frequency analyses of signals. Firstly, time-frequency representations of higher order (TFRHO) are defined. Then L-Wigner distribution (LWD) is given as a special case of TFRHO. Basic properties of LWD are illustrated based on the analysis of mono-component and multi-component synthetic signals and acoustical signals generated by rotating machine. The obtained results confirm usefulness of LWD application for the purpose of rotating machine condition monitoring.
The condition of rotating machines can be determined by measuring of periodic frequency components in the vibration signal which are directly related to the (typically changing) rotational speed. Classical spectrum analysis with a constant sampling frequency is not an appropriate analysis method because of spectral smearing. Spectral analysis of vibration signal sampled synchronously with the angle of rotation, known as order analysis, suppress spectral smearing even with variable rotational speed. The paper presents optimised algorithm for polyphase order analysis based on non power of two DFT algorithm efficiently implemented by chirp FFT algorithm. Proposed algorithm decreases complexity of digital resampling algorithm, which is the most complex part of complete spectral order algorithm.