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This paper deals with an approach to detect face from image with complex background. That can be use in many areas (eg. security systems, biometrics, telecommunications, etc.).In the first part there is presented brief overview of common used method for face localization in image. On the basis of comparison of its properties there was developed appropriate combination of several methods with particular improvements. The goal was to find suitable accuracy to speed rate. Methods were implemented in MATLAB and accuracy rate was tested on Georgia Tech face database. [ABSTRACT FROM AUTHOR]

In this paper, we present a novel mechanism for the multicast congestion control over UMTS networks. The proposed mechanism is based on the well known TCP-Friendly Multicast Congestion Control (TFMCC) scheme. The key challenge in the design of the new scheme lies in improving the TFMCC mechanism to cope with the packet losses caused by either the temporary or the permanent degradation of the wireless channels. The proposed scheme introduces minor modifications in the UMTS nodes with respect to the computing power of the mobile terminals. Finally, our approach is implemented in the ns-2 network simulator and is evaluated it under various conditions. [ABSTRACT FROM AUTHOR]

In practice, different methods for enhancing speech hidden in noise are used but none of the available methods is universal; it is always designed for only a certain type of interference that is to be suppressed. Since enhancing speech masked in noise is of fundamental significance for further speech signal processing (subsequent recognition of speaker or type of language, compression, processing for transmission or storing, etc.), it is necessary to find a reliable method that would work even under considerable interference and will be modifiable for different types of interference and noise. The methods known to date can basically be divided into two large groups: single-channel methods and multi-channel methods. The basic problem of these methods lies in a rapid and precise method for estimating noise, on which the quality of enhancement method depends. If the noise is of stationary or quasi-stationary nature, its determination brings further difficulties. A method is proposed in the article for enhancing the estimation of power spectral density of noise using the wavelet transform. [ABSTRACT FROM AUTHOR]

Localization positioning is one of the basic problems in wide wireless sensor networks. The main objective of positioning process is to define the location of a sensor (node or device) from the relevant information obtained from reference nodes. These nodes already know their location. In many cases, these reference nodes are called beacons. The paper deals with proximity based location technique and their modifications. It does not belong to the most accurate techniques, but on the other hand it is low cost alternative to more expensive techniques. The objective of the paper is to give a survey of various proximity based location techniques performance. We analyze the influence of various design choices on the accuracy of localization techniques. The results of basic proximity based localization techniques are compared with modified proximity technique, which is proposed in this paper. [ABSTRACT FROM AUTHOR]

A cost effective ZigBee-based wireless parking sensor system is presented in this article. Ultrasonic transmitter and receiver are used for distance measurement. An evaluation, control and wireless data transfer are realized by one chip - Panasonic hybrid chip PAN4450 (8-bit microcontroller + IEEE 802.15.4 radio). System consists of four independent distance sensors and one central display and control unit. [ABSTRACT FROM AUTHOR]

This paper describes design and computer simulation of a new architecture of a node active network element, based on artificial neural network technology with the support of priority processing for different connection types. As an example of a network element was selected switching area. This network element with optimized switching area is able to transfer large data quantity with minimum delay. Architecture of network element, that contains artificial neural network for optimized priority switching is described in this paper. It describes implementation of neural network in control process for data units switching. The programming language MATLAB 7.0 was used for software simulation. Network elements with new architecture, which uses a neural network, as well as intimated simulation, are suitable for working for example in personal wireless network communication systems. [ABSTRACT FROM AUTHOR]

A planar structure of the electrodes employed in conductivity measurements is utilizable at small range of conductivity measurement because of small sizes, planar ordering and technology which significantly influence the impedance behavior. The paper presents new approach in the field of precise electrolytic conductivity measurements with planar sensors. This novel measuring method was suggested for measurement using thick-film screenprinted interdigital electrodes (IDEs). Correction characteristics over a wide range of specific conductivities were determined from an interface impedance characterization of the IDEs. A local minimum of the imaginary part of the interface impedance is used for corrections to get linear responses. The method is seeking the optimal frequency for determination of specific conductivity of the solution by IDEs in order to achieve a highly accurate response. The method takes precise conductivity measurements in concentration ranges from 10-6M to 1 M without cell replacement. [ABSTRACT FROM AUTHOR]

The paper describes new approach of potentiostat for very low sensor current measurements. Recent potentiostats were used as measurement devices which were standalone and sensors were connected by a screened wire. These concepts are inconvenient for the presented very low current measurements. The new approach is based on the potentiostat circuitry integrated on a chip that should be directly contacted to a Thick Film Technology (TFT) sensor. [ABSTRACT FROM AUTHOR]

This paper demonstrates that the addition of chemical agents and carbon fibers to cement can greatly enhance the shielding effectiveness of the concrete. In addition to improving the shielding effectiveness, carbon fibers and chemical agents enhance the tensile and flexural strengths significantly. As both carbon fibers and steel fibers are electrically conductive, both can be added to cement to enhance the shielding effectiveness, but steel fibers tend to rust whereas carbon fibers are chemically stable and inert. [ABSTRACT FROM AUTHOR]

The paper deals with a bandpass sigma-delta modulator (BP SDM), which is used for conversion of signal from capacitive pressure sensor. This approach is absolutely new and unique, because this kind of modulator is utilized only for wireless and video applications. The main advantage of BP SDM is due to its defined band. That is why it is resistant against offsets of its sub-circuits. Another important advantage is low power consumption, since the BP SDM digitizes only narrow band instead of whole Nyquist band with similar dynamic range. The paper shows basic ideas of this approach and simulation results. The main stages are implemented in switched-capacitor (SC) technique. The paper presents two possibilities how to design PLL block. The first one is conventional approach and the other one is with digital sigma-delta modulator as generator of input harmonic signal. [ABSTRACT FROM AUTHOR]

Field Programmable Mixed-Signal Arrays (FPAA) designs are reviewed and standard building blocks described with respect to circuit parameters and design limitations. The second-generation current conveyor is introduced as an analog building block with properties similar to those of an operational amplifier, and which has the potential for high frequency operation. A current conveyor can be implemented in an area similar to that of a simple operational amplifier. Potentially greater bandwidths are achieved, while using CMOS technology instead of bipolar technology and test circuit design is proposed. [ABSTRACT FROM AUTHOR]

In the area of analog techniques and primary processing of analog signals in the last decade, some authors have focused on circuits with current or voltage conveyors. Most of them have concentrated on filters with current conveyors, their design and properties, different connections, sensitivity analysis, etc. The present paper is devoted to the basic theoretical description of non-linear circuits with CCII+/-current conveyors in non-filter applications. The basic connections of circuits with current conveyors are chosen, in which a non-linear three-pole is considered, and the functional relations of these connections are established. The applications of non-linear circuits given in the paper are half-wave and full-wave precise rectifiers, which are an analogy to precise measuring rectifiers with operational amplifiers. Rectifiers with current conveyors operating in the current mode can exhibit some positive properties. Only the basic connections are given and the basic functional computer simulations are made here. The active element chosen for the practical rectifier realization was an appropriately connected OTA amplifier. In conclusion, some measurement results are given. [ABSTRACT FROM AUTHOR]

Research and development of Spectrum Administration for metallic access networks analyzed possibilities of matrix representation for transmission circumstances. Some interesting remarks were gained as a side output of this work. [ABSTRACT FROM AUTHOR]

The paper presents complex treatment and measurement system based on USB and its enhancements. The article is divided into two parts. The first one deals with up-to-date USB enhancements which are USB On-The-Go, USB Test & Measurement Class, Wireless USB, PictBridge, PoweredUSB, Inter-Chip USB, Battery charging specification. The second part presents the practical usage for measurement and therapeutical system. [ABSTRACT FROM AUTHOR]

Contemporary optical fibers can deal with almost all of the unfavorable effects which are known these days. They have sufficiently low specific slump, they can handle a slump caused by OH-ions, they can restrain the multimode effect and finally they can compensate a chromatic dispersion. But there is one problem, which the present science can't solve and this problem is the Polarization Mode Dispersion (PMD). This effect is a restricting factor of high-speed long-distance optical routes. The capacity increase of the existing optical routes is more often realized by multiplexing methods. Using more wavelengths makes multiplication of the optical fiber transfer rate possible. It evokes not only the advancement of fiber letting (known as "Dark Fiber" service), but more often also a single wavelength letting. [ABSTRACT FROM AUTHOR]

This article deals with active frequency filter design using signalflow graphs. The procedure of multifunctional circuit design that can realize more types of frequency filters is shown. To design a new circuit the Mason-Coates graphs with undirected self-loops have been used. The voltage conveyors whose properties are dual to the properties of the well-known current conveyors have been used as the active element. [ABSTRACT FROM AUTHOR]

Novel second-order multifunction filters operating in current mode are described. Their structure is based on three current operational amplifiers connected in a feedback loop. These active elements are dual to the well-known operational amplifiers and are suitable for high-frequency signal processing. The designed filters offer low-pass, band-pass and high-pass transfer functions simultaneously. Computer simulation is carried out to prove the functionality of a filter variant. The influence of real properties of active elements is analyzed. [ABSTRACT FROM AUTHOR]