Since the early days of the Internet, TCP has been the premier transport protocol for most if not all applications. TCP predates IP and was designed to run over any packet-switching wireline network environment where errors due to the underlining medium are an exception rather then a rule. This complex protocol, in addition to many services such as flow control, congestion management and reliability, attempts to provide both an efficient utilization and a fair share of network resources. Wireless and mobile networks generate an environment in which TCP may suffer severe performance degradation due to possible misinterpretation of random losses that come from high BER, low and variable bandwidth, and frequent disconnections. The reason is the triggering of the congestion management mechanisms in response to the losses since TCP assumes by default that a lost packet is an indication for network congestion. The results are a decrease in throughput, poor resource utilization and eventually an unacceptable performance of the applications. There is no alternative in making TCP understand heterogeneity through modification and enhancement of the algorithms that the protocol consists of. Naturally, there are options that are enumerated in the article, but in the model we propose the preservation of the E2E semantics is an imperative. In addition to an overview of the "mainstream" research area, this article present the deployment of the loss pair method as a possible solution to some congestion management issues and thus making heterogeneity transparent to TCP.

In this paper a simple and complete asymptotical analysis is given for a switched piecewise uniform quantization of two-dimensional memoryless Laplacian source with the respect to distortion (D) i.e. the mean-square error (MSE). Piecewise uniform quantization consists of L different uniform vector quantizers. Uniform quantizer optimality conditions and all main equations for optimal number of levels and constant (nonoptimal) number of output points for each partition are presented (using rectangular cells). Switched quantization is used in order to give higher quality by increasing signal-to-quantization noise ratio (SNRQ) in a wide range of signal volumes (variances) or to decrease necessary sample rate. These systems, although not optimal, may have asymptotic performance arbitrarily close to the optimum. Further more, their anaysis and implementation can be simpler than those of optimal systems.

New Pb-free materials ask thorough verification because their properties as wetting, solderability and mechanical properties are different from these SnPb. In this paper are presented some new facts from creep and stress relaxation investigation including new arrangement for measurement. Results from creep, stress, shear and bend testing are presented for three types of solder (Sn/3.5Ag, Sn/3.8Ag/0.7Cu and Sn/37Pb).
The basic sample was made from copper plate with thickness of 2 mm. An aperture was created through the middle of sample with the length of approximately 2/3 of its length to be filled with solder paste. Since solder paste changes its volume after soldering is applied, the samples were polished to provide flat surface. For creep and stress relaxation testing was used Electro-thermal Mechanical system. This enables to measure displacement as a function of shear stress.
Most failures of solder joints, which occur in electronic systems, are troubles caused by the thermal mismatch among different materials involved in electronic system construction. One of main reasons is different coefficient of thermal expansion (CTE) of materials that are assembled together. During the manufacturing and operation time, the structure goes through various temperature cycles, which cause thermal expansion. Materials cannot expand freely, because they are constrained by the packaged assembly. Therefore, significant stresses are induced in solder joints. These stresses creating destruction of solder joints can be mathematically modeled using ANSYS software and compared with experimental results.

Decision support systems (hereinafter DCS only), mean interactive computer systems, which assist to decision making subjects to utilize both data and models to solve non-structurized issues. These systems were established mainly based on a risk analysis, utilizing the experience/skills, conclusion making and intuition, enabling very fast and flexible analysis with a good response, enabling the application of manager intuition and judgment this way. However such decisions are often based on uncertain information, which fact requires establishment of other decision support models.

This paper illustrates the application of one component of OFFICE package - Excel - in circuit theory and describes two special programs for the three-phase circuits in harmonic steady state analysis. In the first order it is shown how to access that the basic functions of Excel will work with complex numbers, further all two programs are described and illustrated. First of them is for the connection format of three-phase appliance Y analysis and the second for the appliance of connection format D analysis. Three-phase circuit with the appliance of connection format Y analysis means phase current computing, as well as the real, reactive and complex power transmitted by three-phase load and reactive and complex power on the appliance. Three-phase circuit with the appliance of connection format D analysis means phase and load current computing, the real, reactive and complex power transmitted by three-phase load and real, reactive and complex power on the appliance. Both these programs grant to draw the phasor diagram of voltage and current phasors as graphic representation of the results. The failure states (short connection or disconnection of some phase) analysis is also possible. These programs can be found on the http:// www.tuke.sk\fei-kteem/aei06/y.xls and http:// www.tuke.sk/fei-kteem/aei06/d.xls.
Presented programs grant to do the full analysis of three-phase circuits. Our goal is to prepare studying materials for the course Theory of electrical engineering with included programs in Excel for graphical illustration of analysis results for the circuits with anharmonic sources, graphic illustration of analysis results for the simple circuits with pulse on the input, full computer processing of long distance line analysis including graphics illustration of results.

In the article there is described a frequency-sweep nuclear magnetic resonance (NMR) spectrometer when a static magnetic
field runs at a fixed value. The repetitive frequency-sweep of oscillator is realized by a variable frequency divider in the feedback
loop of the second-order Phase Locked Loop. The largest advantage of this system for the CW NMR spectrometer is a good
possibility of repetitive passages over resonance in case when NMR signal is very weak and the S/N ratio increase is necessary.
The experimental results show that this system with the low-noise NMR oscillator is very useful for th et detection of the broadline
NMR signals.

Electrical action of higher performance of permanent magnets synchronous motors requires advanced control strategies related to complex dynamic behaviour of machines. Most of these machines are not linear and are characterised by structural or non structural uncertainties varying with time which make their control very complicated to be implemented. To solve this problem many approaches have been developed. The backstepping control allows to guarantee the robustness of uncertain and disturbed systems by attenuation of the effects of external disturbances to a desired level. This paper is intended to put into evidence the control behaviour based on this new technique. This will be applied to permanent magnets synchronous machine.
 

Contribution deals with learning design templates combination and overlapping and describes some important ideas behind our concept and methodology of multidimensional, layered and template based educational courses creation that increases reusability. In context of templates combining we illustrate application of Object Constraint Language (OCL) for precise templates modeling and specification. We deal with concrete example which transforms template from the structural to behavioral view and joins it within two-dimensional template covering role aspects. Described methodology allows instructional design of complex learning courses for existing environments and Learning Management Systems compatible with the ADL Shareable Content Object Reference Model (SCORM) and IMS Learning Design (LD) specifications.

The state of a system is expressed using PFL, a process functional language, in an easily understandable manner. The paper presents PFL environment variable - our basic concept of the state manipulation in the process functional language. The concept of the process functional language has been extended with an object-oriented paradigm features. The paper presents an abstract syntax of the object-oriented PFL and describes the syntax of types and type environments. In the paper main ideas of object-oriented PFL type checking and program translation in a compiler are explained. Finally the paper presents an example where type environments are inferred as a result of PFL program translation. Presented results described in this paper were implemented in PFL compiler.