bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of the seasonal cycle of surface layer salinity in the global ocean
Authors: Bingham F. M. , Foltz G. R. , McPhaden M. J.
Published: December 2011

Abstract. The seasonal variability of surface layer salinity (SLS), evaporation (E), precipitation (P) and E-P over the global ocean is examined using in situ salinity data and the National Center for Environmental Prediction's Climate System Forecast Reanalysis. Seasonal amplitudes and phases are calculated using harmonic analysis and presented in all areas of the open ocean between 60° S and 60° N. Areas with large amplitude SLS seasonal variations include: the intertropical convergence zone in the Atlantic, Pacific and Indian Oceans; western marginal seas of the Pacific; and the Arabian Sea. The median value in areas that have statistically significant seasonal cycles of SLS is 0.19. Between about 60° S and 60° N, 37 % of the ocean surface has a significant seasonal cycle of SLS and 75 % a seasonal cycle of E-P. Phases of SLS have a bimodal distribution, with most areas of the ocean peaking in SLS in either March/April or September/October. The same calculation is done with surface freshwater flux using a mixed-layer depth climatology. With the exception of an area near the western boundaries of the North Atlantic and North Pacific, seasonal variability is dominated by precipitation. Surface freshwater fluxes also have a bimodal distribution, with peaks in January and July, 1–2 months before the peaks of SLS. The amplitudes and phases of SLS and surface fluxes compare well in a qualitative sense, suggesting that much of the variability in SLS is due to E-P forcing. However, the amplitudes of SLS are somewhat larger than would be expected and the peak of SLS comes typically about one month earlier than expected. The differences of the amplitudes of the two quantities is largest in such areas as the Amazon River plume, the Arabian Sea, the ITCZ and the eastern equatorial Pacific and Atlantic, indicating that other processes such as ocean mixing and lateral transport must be important, especially in the tropics.
What is the 'Fight Against Corruption' in Nicaragua?
Authors: Cloke Jon
Published: December 2011

Two hundred years ago in Great Britain, the political system was dominated by electoral power exercised through rotten boroughs, a system characterized by institutionalized corruption - these electoral boroughs were owned by local elites, and voting was restricted to a handful of people. Whilst industrially she was the wonder of the world, the political system in Great Britain was restricted, corruption was the norm, and it seemed impossible to imagine that such an ancient system could be changed. By the time of the Reform Act of 1832 however, Britain had already been going through a process of constitutional change lasting for hundreds of years – it is only now, from our position of 20/20 hindsight, that we choose to interpret all of the events since the signing of the Magna Carta in 1215 as if it were some seamless whole, an inevitable process that would lead to the position of superior moral governance that we appear to think we are in now.
Ventanas en la Memoria: recuerdos de la Revolución en la Frontera Agrícola, de Fernanda Soto Joya
Authors: Najlis Michele
Published: December 2011

Como vemos en el libro, Fernanda realiza esta investigación para optar al doctorado en Antropología. Pero también, y quizá sobre todo, para conjurar sus pensamientos, angustias, fantasmas y dolores; que son también los de esta generación a la que pertenezco y posiblemente también de la generación intermedia (la de mi hijo mayor Túpac, la de Vidaluz Icaza, José Luis Rocha y de otros entonces chavalos y chavalas que cortaron café y algodón, y que, con 14 ó 15 años, integraron batallones que fueron a las zonas de guerra).
Expulsados de la globalización: políticas migratorias y deportados centroamericanos de José Luis Rocha
Authors: Huezo Mixco Miguel
Published: December 2011

Como escribe Rocha: “La criminalización y penalización de las migraciones internacionales ha devenido en sentido común, plenamente legitimado por las leyes, la opinión pública y los aparatos coercitivos estatales. Los centroamericanos que quieren vivir el sueño americano son abruptamente despertados a una pesadilla de redadas, prisiones y deportaciones”. Mucha de esta pesadilla proviene de lo que el autor, retomando un ensayo de Todorov, denomina “el miedo a los bárbaros”, un miedo que se ha convertido en una verdadera pasión en los países industrializados, cuyas grandes ciudades son la meca de los migrantes.
In Vivo Ciprofloxacin Release from Hydroxyapatite-Based Bone Implants in Rabbit Tibia: A Preliminary Study
Authors: Nayak Amit Kumar , Bhattacharyya Ajoy , Sen Kalyan Kumar
Published: December 2011

The present study deals with the preliminary evaluation of in vivo ciprofloxacin release from HAp-ciprofloxacin bone implants in rabbit tibia. The HAp-ciprofloxacin implants ( mm) were prepared using various HAp-ciprofloxacin composites synthesized by precipitation technique and 1.5% w/v guar gum as a binder. 5 implants were implanted in artificial cortical bone window at the right proximal tibia of each rabbit. After 3- and 6-day intervals, the rabbits were euthanized. Bone marrow and serum concentrations of ciprofloxacin were determined from the harvested tibia using HPLC method. The results displayed the availability of elevated local antibiotic concentration at the implanted site with the limitation of systemic antibiotic exposure, which can be useful to minimize the risk of systemic toxicity-related side effects. This study is the preliminary investigation of the suitability of in vivo ciprofloxacin release from HAp-ciprofloxacin bone implants in rabbit tibia, after implantation, and these implants can be useful for the treatment of bacterial bone infections like osteomyelitis.
Pygmalion in the Laboratory
Authors: Gardner R. Allen , Scheel Matthew H. , shaw Heidi L.
Published: December 2011

Testers and bystanders can inadvertently lead subjects to answers in laboratories and in classrooms, in face-to-face tests of human beings and other animals. Many modern investigators avoid leading by using blind tests scrupulously. This article shows how to design blind tests and illustrates common methodological errors that allow leading to confound experimental results. The object is to help experimenters, editors, and readers detect and avoid a common experimental error that often has profound theoretical implications.
Collision Avoidance Concept for the ATC Expert System
Authors: Sinuks I.
Published: December 2011

Despite the fact that there is unimaginable technological achievement in communication, navigation, surveillance, computation and control, the ATM system suffers from the lack of automation abilities. Almost all main processes of ATM are based on a rigidly structured airspace and centralized human-operated system architecture, but increasing the level of automation we could improve the efficiency of ATM and the human-operator tasks could be simplified. The core objective of any ATM is to guarantee safety and efficiency. The main purpose of this work is to provide theoretical investigation of serious questions in ATC system and in ATC working process. This publication is a continuation of previous work on concept of expert systems that could be used in ATC. Using appropriate knowledge in ATC physics, procedures and technology processes the ways to increase efficiency of Air Traffic Control (ATC) are found that do not destroy the safety level of whole ATM. The analysis of conflict characteristics, collisions and avoiding actions will be a knowledge base for future ATC expert system. Logical expert systems are similar to human operators that are using own knowledge bases, not mathematical functions, and are flexible for solving different typical problems of normal life. Ill. 2, bibl. 4 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.108.2.133
Energy Efficiency Comparison with Cipher Strength of AES and Rijndael Cryptographic Algorithms in Mobile Devices
Authors: Toldinas J. , Stuikys V. , Damasevicius R. , Ziberkas G. , Banionis M.
Published: December 2011

We analyse energy efficiency vs. cipher strenth of AES/Rijndael crypto algorithms in a mobile device with respect to block and key size. The experimental results show that Pareto-optimal solutions have equal block and key sizes. We also propose three energy/security profiles for the users of mobile devices. As decryption operation requires 14% more energy than encryption, the results of energy consumption measurements when performing data encrypion can be used to predict energy consumption of decryption operation. Ill. 5, bibl. 10, tabl. 2 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.108.2.134
Motor Control using Discontinuous Signals
Authors: Aghion C. , Ursaru O.
Published: December 2011

This paper makes a comparative analysis of the behaviour of an alternating current motor with different control methods. Two control techniques were used, based on discontinuous reference signals, namely DPWM-S4 and DPWM-S5. Ill. 9, bibl. 7, tabl. 1 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.108.2.135
Analysis of Rejection Properties of Meander Systems
Authors: Katkevicius A. , Staras S.
Published: December 2011

Influence of transverse asymmetry of meander systems on their frequency characteristics and rejection properties is considered. The model of the systems based on the multiconductor line method is used. Examples of calculated characteristics are presented. Properties of non-homogeneous meander structures, asymmetrical with respect to the longitudinal plane perpendicular to the central part of the system, are revealed. In the meander system containing electrodes with wide central parts of meander conductors and narrowed peripheral parts, the stop-band appears at q = p where q is the phase angle between voltages or current on neighbor conductors. At transverse asymmetry, the period of inhomogeneities along the meander conductor becomes two times greater with respect to the period of inhomogeneities at absence of transverse asymmetry, wherefore input impedance rapidly changes and the stop-band appears when phase angle q approaches to p/2. Increase of variation of characteristic impedances Z(0) or Z(0) or Z(p) followed by increase of the width of the stop-band. Ill. 5, bibl. 14, tabl. 3 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.108.2.136
Analytical Estimation of Self-Similar Wireless Traffic Relaxation Time and Hurst Coefficient Dependence
Authors: Yeryomin R. , Petersons E.
Published: December 2011

Analyzed formula can be used for finding system relaxation time depending on what server load is and how high is input traffic self-similarity degree. It was found that the best result is achieved with Verhulst equation. Ill. 6, bibl. 6, tabl. 2 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.108.2.139
Investigation of Signalling Flow Transfer Processes based on SCTP Protocol
Authors: Jarutis A.
Published: December 2011

To establish reliable signalling information transmission over IP network is used SIGTRAN protocol containing a protocol with the transport flows. This protocol, uses signalling messages over IP network, to determine maximum time and number of repetitions. Reports contain the signalling messages transmission over IP network algorithm, which simulated a notification request over IP network, taking into account differences in SCTP message transmission time. A provisional value of transmission characteristics over IP network is determined. Ill. 8, bibl. 7, tabl. 1 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.108.2.140
Dual-Hop System Analysis in Nakagami-m Environment
Authors: Cvetkovic A. D. , Stefanovic M. C. , Sekulovic N. M. , Mekic E. S. , Manic D.
Published: December 2011

In this paper, performance analysis of dual-hop transmission system is presented. The source-relay (S-R) and relay-destination (RD) channels experience Nakagami-m fading. The generalized case in which desired signal and cochannel interference (CCI) experience mutually different amount of fading is considered. Furthermore, analysis includes the case in which fading severity in S-R and R-D links can be unequal which is real scenario in practice. Outage probability, as an important performance measure, is considered. As an illustration of mathematical formalism, numerical results are presented to show the effects of system and channel parameters on overall performance. Ill. 5, bibl. 5 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.108.2.143
Analytical Method for Differential Amplifier Offset Voltage Analysis
Authors: Baskys A. , Nickelson L. , Navickas R.
Published: December 2011

The analytical method for differential amplifier offset voltage analysis is presented in the work. The method is developed for the amplifier based on the bipolar junction transistors that operate at high-current density. The transistor model based on the equation of the junction, which takes into account the dependence of majority carrier boundary concentrations on junction voltage that should be considered at high-current density, is used as the base for derivation of input offset voltage equations. The derived equations are valid in the narrow region of current, at which the differential amplifier input offset voltage measurement is provided. The obtained equations allow us to estimate the input offset voltage reduction ways. The results gained using suggested analytical analysis method are confirmed by the numerical investigation of the differential amplifier. Ill. 3, bibl. 11 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.108.2.144
Wavelet Based Reference Current Calculation Method for Active Compensation Systems
Authors: Gokmen G.
Published: December 2011

Today, active compensation systems have become more preferable compared with passive compensation systems. Performance of an active compensation system depends on current control method of the compensator as well as how this current is generated. In this study, a Discrete Wavelet Packets Transform (DWPT) based method was proposed for calculating reference current of active compensation systems and the results were compared with the currents produced from classical p-q theory. According to the obtained results, the proposed method can be used in active compensation systems without using an additional signal processing and filtering method. Ill. 12, bibl. 21, tabl. 1 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.108.2.146
Mitigation of Magnetizing Inrush Current using Sequential Phase Energization Technique
Authors: Jamali M. , Mirzaie M. , Asghar-Gholamian S.
Published: December 2011

Energization of a transformer under no load or lightly loaded conditions may result in inrush current with high amplitude that can be comparable with the fault currents. These currents have undesirable effects, including malfunction of the differential relay, mechanical and thermal stresses on transformer and reduced power quality of the system. In this paper, a sequential phase energization technique has been used to mitigate magnetizing inrush current in a grounded system. Because in this technique, the size of the resistor, which is connected to the neutral point of the transformer, has an important role, analytical formulas have been derived to calculate inrush current amplitude with a neutral resistor. These analytical formulas have been implemented in the M-File of the MATLAB software for calculation of different inrush current reduction ratio. Then for the verification of the results, the obtained neutral resistor has beenapplied to the equivalent circuit of a typical three-phase transformer and inrush current reduction has been determined by MATLAB SIMULINK. Ill. 7, bibl. 13 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.108.2.147
Switched Semilogarithmic Quantization of Gaussian Source with Low Delay
Authors: Mosic A. , Peric Z. , Savic M. , Panic S.
Published: December 2011

In this paper, a novel companding model based on nonuniform scalar quantization switching technique of Gaussian source is presented. A - law compandor implementation is observed. This scalar quantization model, with quantizers adapted to the maximal amplitudes of input signals, provides higher quality of signal-to-quantization noise ratio in a wide range of signal volumes, with respect to it's necessary robustness over a broad range of input variances. The main contribution of this model is achieving higher quality of transmission and possibility of its applying for digitalization of continuous signals in wide range. Ill. 5, bibl. 8, tabl. 1 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.108.2.148
Nonlinear Control based on Feedback Linearization for Double- Electromagnet Suspension System
Authors: Maghsoudlou A. , Barzamini R. , Farahani K. D.
Published: December 2011

In this paper a feedback linearization control for double electromagnet suspension system is presented that addresses the coupling effects between two groups of electromagnetic trains. The controller has been developed based on feedback linearization and some reasonable assumptions of nonlinear mathematical rules. The proposed method in tracking has a satisfying performance in presence of unknown changes in the mass. It also shows robustness against the presence of measurement noises because sensors in plant collect noise from the environment. The simulation results show the capability of the proposed algorithm in the presence of input and output perturbation. Ill. 13, bibl. 7 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.108.2.151
A New Approach for an Efficient DTW in Face Detection through Eyes Localization
Authors: Adwan S. , Arof H.
Published: December 2011

This paper presents an innovative method of face detection by supplementing dynamic time warping algorithm with proposed image processing strategy and weighting scheme. Using our proposed approach overcomes some of the shortcomings in applying dynamic time warping for face detection, hence improving the performance and detection accuracy. The results presented and discussed in this paper show the efficacy of our approach in using DTW for face detection. Ill. 16, bibl. 16, tabl. 1 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.108.2.154
The Joint Probability Density Function of the SSC Combiner Output Signal at two Time Instants in the Presence of Log-Normal Fading
Authors: Krstic D. S. , Nikolic P. B. , Stefanovic M. C. , Destovic F.
Published: December 2011

In this paper the probability density function of the Switch and Stay Combiner (SSC) output signal at one time instant and the joint probability density function of the SSC combiner output signal at two time instants, in the presence of log-normal fading, are determined in the closed form expressions. The results are shown graphically for different variance values and decision threshold values. If the digital telecommunication systems work on the manner described in this paper, the error probability will be significantly reduced. Ill. 6, bibl. 24 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.109.3.161
Calculation and Analysis of Transformer Inrush Current Based on Parameters of Transformer and Operating Conditions
Authors: Jamali M. , Mirzaie M. , Asghar-Gholamian S.
Published: December 2011

An inrush current is a transient current with high amplitude that may occur when a transformer is energized under no load or lightly loaded conditions. The magnitude of inrush current may be as high as ten times or more times of transformer rated current. This could result in huge mechanical and thermal stresses on transformer in addition to inadvertent operation of the protective relay systems. This paper represents the effects of some factors on the inrush current of transformers. For this purpose, a one-phase transformer is simulated in MATLAB and the effects of switching angle variation, the energizing circuit impedance and the remanent flux on the characteristics of inrush current are investigated. The results show that increasing circuit resistance or switching angle will decrease inrush current amplitude. Also, it is concluded that for reducing inrush current, appropriate switching angle with respect to the remanent flux must be selected. The results can be used for a better understanding of the inrush current characteristics and proper actions of the protective system. Ill. 7, bibl. 13, tabl. 1 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.109.3.162
Analysis of Balanced Three-Phase Induction Motor Performance under Unbalanced Supply using Simulation and Experimental Results
Authors: Temiz I. , Akuner C. , Calik H.
Published: December 2011

Induction motors are known to affect the electrical power system in terms of harmonics. Induction motors fed by unbalanced power systems produce additional current harmonics. These harmonics cause additional power losses in the machine. The method of symmetrical components is often used in this kind of unbalanced operation analysis. In this study, the performance of a three phase induction motor supplied by unbalanced power system due to the various causes has been examined using both experimental method and Matlab/Simulink model. Ill. 11, bibl. 6, tabl. 6 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.109.3.167
Measurement of the Depth of Spee's Curve using Digital 3D Dental Models
Authors: Adaskevicius R. , Svalkauskiene V.
Published: December 2011

Aim of our study is to consider a possibility of using 3D computer models for measurement the depth of curve of Spee. Curve of Spee is very important in diagnostics of orhtodontical patient. The structured-light three-dimensional (3D) scanner was used for scanning dental casts. The cusp tips of the molars, premolars, and incisors of the mandible were identified using digital 3D models and Rapidform 2006 software. The depth of the curve of Spee was evaluated by means of our computer software. Algorithm for depth of Spee's curve evaluation is presented. The dental casts of 15 subjects were scanned and measured to test the reliability of method contrasting with conventional manual measurement. The depth of Spee's curve was measured 7 times for every dental cast and repeatability of conventional and digital measurement methods was compared. Within a confidence interval of 95%, we could say that measurement results of depth of Spee's curve using two different methods don't differ more than 0.5 mm. Three-dimensional digital dental models is useful tool for analysis of depth of Spee's curve and treatment planning. Ill. 4, bibl. 11 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.109.3.170
Investigation of Microcoils for High Magnetic Field Generation
Authors: Grainys A. , Novickij J.
Published: December 2011

Microcoils design for high pulsed magnetic field generation is described. A possibility to generate micro and sub-microsecond magnetic field pulses in 1 - 10 T range is analyzed. Pulsed facilities consisting of high voltage power supply, low self-inductance capacitor bank and fast high voltage solid state switches connected in parallel and in series are able to generate high power 1 kA, 0,51,0 )µs pulses. Three different prototypes of single, dual and multiturn microcoils are investigated. Analytical and finite element methods are used for modelling of transient electromagnetic and thermodynamic processes. Computer simulation results of current density, thermal overloads and calculations of axial magnetic flux density are presented and recommendations for further experiments are offered. Ill. 7, bibl. 13 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.109.3.172
Stabilization of Motion Trajectories of Servo Drive on Varying Parameters of Control Object Conditions
Authors: Gelezevicius V. A.
Published: December 2011

Practical approach designated for programmed trajectories of servo drive operating on varying parameters of transported object conditions stabilization is proposed and investigated in the paper. It is proposed in combination with MRSAC method, introduced in to speed control subsystem, to use means limiting derivative of position controller output signal. It is shown that in order to enlarge the permissible range of inertia moment variation the speed controller of speed regulation module should be adjusted under the maximum supposed inertia moment value The modelling results of the system are given. Ill. 5, bibl. 3 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.109.3.176
Induction Motor Voltage Amplitude Control Technique based on the Motor Efficiency Observation
Authors: Bleizgys V. , Baskys A. , Lipinskis T.
Published: December 2011

The technique of voltage amplitude control of AC induction motor supplied by the frequency converter has been proposed. It is based on the observation of motor phase current amplitude value. The amplitude of motor supply voltage is controlled in real time in such a way that for given instant motor load and speed the phase current amplitude would be minimal, i.e. the efficiency of the motor would be maximal. The realization of this method of voltage amplitude control is less complicated as compared to vector control. It is enough to provide the continuous measurement of motor phase current amplitude and to find in the real time the amplitude of voltage, at which phase current amplitude is minimal. The proposed technique can be applied in the situations when the fast response of the motor supply voltage amplitude is not needed. The developed technique has been investigated experimentally using special test bench. Ill. 6, bibl. 11 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.109.3.178
Load Optimization of Heat Exchanger Cascades
Authors: Sipal J.
Published: December 2011

This paper explores the load variant efficiency of heat exchangers. An empirical model of efficiency as a function of heat exchanger load is presented. This model can be used to optimize the load distribution among heat exchangers in heat exchanger cascades. As a result, the efficiency of district heat exchanger stations can be significantly increased. The efficiency increase depends on the load but it can be approximately doubled for a significant interval of loads. Ill. 4, bibl. 5, tabl. 2 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.109.3.179
Computation of Electric Wind Parameters in Direct Current Corona Field
Authors: Gudzinskas J. , Marčiulionis P. , Žebrauskas S.
Published: December 2011

Digital model for analysis of two-dimensional direct current corona field and induced electrohydrodynamic air flow field in wire-to-plane electrode system is discussed. Finite-difference method in polar coordinate system is used for corona field computation. Results of computation of corona field are checked by comparison of digital and experimental data of current-voltage characteristics. Maximum difference of these values of linear current density is 150 µA/m corresponding to the voltage value of 7 kV. The digital model of EHD air flow field consists of finite-difference approximation of the Navier-Stokes equation and the continuity equation in Cartesian coordinates. Check of digital velocity values by comparison of these values with the experimental ones is only qualitative because of the distortion of corona field and air flow field by the probe of hot-wire anemometer. Ill. 6, bibl. 6 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.275
Digital Automatic Control System with PID Controller
Authors: Petrovas A. , Lisauskas S. , Rinkeviciene R.
Published: December 2011

The design process of digital automatic control system with PID controller is considered. The solution of problems related with implementation of PID control algorithm into general purpose 8-bit microcontroller is discussed. Simulation results demonstrating performance of system are presented. Ill. 4, bibl. 6, tabl. 3 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.277
Mechanical Characteristics of Linear Asynchronous Motor
Authors: Boudiaf A. , Aissani Z. , Bentriou A.
Published: December 2011

This work is concerned with the computations of the active forces in a unilateral linear asynchronous motor (LAM) without an inverse magnetic circuit, for both magnetic and unmagnetic moving bodies. Field and force computations were conducted and results analyzed. 1ll. 3, bibl. 4 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.279
Practical Fuzzy-CAC Realization for Effective Traffic Engineering in MPLS-TE Networks
Authors: Jelinskis J. , Skrastins A. , Lauks G.
Published: December 2011

In this investigation the new Fuzzy-CAC algorithm practical implementation of RSVP-TE protocol development for use in MPLS-TE/GMPLS networks is presented. Fuzzy-CAC algorithm is tested on the MPLS-TE network testbed with 3 Cisco 2800 series routers, on which classical threshold CAC algorithm is compared to the Fuzzy-CAC algorithm implementation. Main QoS characteristics are analyzed, experimental data are depicted and future research subjects are described. Ill. 14, bibl. 9, tabl. 4 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.281
Estimation of Critical Components of Internet Infrastructure
Authors: Kajackas A. , Rainys R.
Published: December 2011

The article analyses the connectivity of Internet - one of the fundamental network characteristics - on the basis of network topology analysis. The metrics compiled allows identifying the critical elements of Internet network infrastructure: critical and ɳ-critical nodes and critical as well as critical and k-critical links. The model of monitoring the critical network elements was created, and the algorithm of realizing was described. Ill. 1, bibl. 11, tabl. 1 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.282
Optimization of Sensor Grid aided by Modelling of Sensor Relationships with Digital Filters
Authors: Gorecki J. , Miedzinski B.
Published: December 2011

The paper discusses optimization method based on the coverage probability. Presented optimization method can be applied both in the symmetrical sensor grids and asymmetrical sensor grids where sensors are not distributed uniformly. It is revealed that applying post-processing calculations like linear-regression makes incredible improvement in the optimization process. However despite of good correlation between particular sensors, there is a significant risk that causal connection between correlating and correlated sensor does not exist. This paper describes how to detect causal dependency. Ill. 2, bibl. 5, tabl. 2 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.283
Efficiency of Electronic Devices for Unsteady Flow of Failures
Authors: Eidukas D. , Stupak V.
Published: December 2011

Electronic devices inspected by using built-in test equipment are analyzed. The method of calculation of efficiency of devices for a case of unsteady Poisson flow of failure is offered. The method is based on estimation of the bottom and top limits for values of efficiency on analyzed interval of exploitation. For this purpose, efficiency of devices for corresponding Poisson flows of failures is calculated. A relative error of definition of efficiency value is defined. As an estimation of an error, its maximal value is used. Computing experiment according to the given error is executed. Experiment considers really possible values of the parameters influencing efficiency of the device. Results of experiment show that the maximal relative error of an estimation of a parameter of efficiency does not exceed 6.5 % . Bibl. 9, tabl. 1 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.287
A Static Synchronous Compensator for Displacement Power Factor Correction under Distorted Mains Voltage Conditions
Authors: Cimbals R. , Krievs O. , Ribickis L.
Published: December 2011

A STATCOM system is presented in this paper applied for compensation of displacement power factor under distorted mains voltage conditions. The developed STATCOM control system consists of two regulating loops - DC link voltage control loop with anti-windup PI controller and the current control loop with a feed-forward PI controller. The simulation results indicate that the developed control system performs well, ensuring displacement power factor compensation with good transient and steady state performance even under significantly distorted grid voltage conditions. Ill. 15, bibl. 8 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.291
Prognostication of Cardiovascular Outcomes in Patients with Acute Coronary Syndromes
Authors: Babarskiene M. R. , Vencloviene J. , Luksiene D. , Milvidaite I.
Published: December 2011

Ischemic heart disease is the leading cause of death in Europe among males over 45 years of age and females older than 65. The aim of the study: to evaluate the informative value of the models in ACS patients using GRACE (GR) risk score, to identify additional informative indicators for short-term and long-term prognosis following ACS, and to evaluate the prognostic reliability of the integrated model. The study included 1491 patients who in 2005 were treated for ACS in the Department of Cardiology, the Hospital of Kaunas University of Medicine. We devised an adjusted prognostic index for making short and long-term prognosis in patients with acute coronary syndromes (STEMI and NSETMI). Following adjustment of the GR scores, the prognostic value improved for STEMI patients. Ill. 2, bibl. 12, tabl. 3 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.292
Piece-Linear Aggregates for Formai Specification and Simulation of Hybrid Systems: Pharmacokinetics Patient-Controlled Analgesia
Authors: Pranevicius H. , Simaitis L. , Pranevicius M. , Pranevicius O.
Published: December 2011

Piece Linear Aggregates formalism (PLA) for specification and simulation of hybrid systems, when continuous components are described in ordinary differential equations (ODEs). PLA is used to create Quantized State System (QSS) model. QSS is integration based method, created for ODE solving. Since QSS method first was introduced for use in Discreet Event Systems (DEVS) formalism, we adapted it for PLA formalism, which is fundamentally consanguineous to DEVS formalism. Pharmacokinetics model is used as example of hybrid system. Pharmacokinetics is a branch of pharmacology which describes administered drug absorption and distribution in human body. In pharmacokinetics drug distribution is described using ODE. In order to use drug injection in pharmacokinetics model, we have to modify standard QSS model and add some specific capabilities. Result: modified QSS method was obtained and used for pharmacokinetic model specification. Simulation of morphine concentration in plasma was performed using real pharmacokinetics data to test Patient-Controlled Analgesia (PCA) method effectiveness. Ill. 2, bibl. 6 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.293
Parallel Algorithm Evaluation in the Image and Clustering Processing
Authors: Pughineanu C. , Balan I.
Published: December 2011

The increase of the information volume of the image type in the greatest part of the domains asks for the introduction of some storage and efficient recovery methods of the available data due to content. Unfortunately, the progress registered in the field of the multimedia databases with digital images is not remarkable as being outdated by info explosion. The article proposes compression algorithms aiming to reduce the quantity of data necessary to represent an image and the necessary clustering algorithms, namely the k-means algorithm and ISODATA, which were parallelized both from the point of view of the extracted areas and the execution time. The experimental results were obtained by the implementation of the algorithms using the MPI standard and their execution on a cluster. Ill. 12, bibl. 16 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.295
Design of the Deadbeat Controller with Limited Output
Authors: Balasevicius L. , Dervinis G.
Published: December 2011

There is presented a method for finding the parameters of the deadbeat controller in Matlab environment. The method is based on the introduction of an additional polynomial into the transfer function of the controller. The method for determining the additional polynomial coefficient of a deadbeat controller is based on creating the family of the coefficient curves and defining the permissible selection area. The method was tested by using simulations in Matlab environment and realizing the deadbeat control system for the third order object in the PLC. Simulation results in Matlab show that even though the control increases by one-step, the settling time of the system response can be lower than that of the deadbeat controller without any modifications. Based on the obtained results it can be concluded that the results confirm the idea of defining the parameters of the transfer function of a deadbeat controller with a limited output. Ill. 9, bibl. 3 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.296
Hierarchical Control Approach for Autonomous Mobile Robots
Authors: Proscevicius T. , Bukis A. , Raudonis V. , Eidukeviciute M.
Published: December 2011

Methods for intelligent mobile robots control which are based on principles of hierarchical control systems will be reviewed in this article. Hierarchical intelligent mobile robots are new direction for development of robotics, which have wide application perspectives. Despite increasing progress in technologies, the main problem of autonomous mobile robots development is that, they are ineffective in their control. In each of the hierarchical control levels (movement in space, problems solving and signal processing sets) will define by specific management of objectives, goals and rules. Communication and management between hierarchies are implemented by higher level of hierarchy using obtained information about the environment and lover level of hierarchy. Studies have shown that artificial neural networks, fuzzy logic are widely used for the development of the hierarchical systems. The main focus of the work is on communications in hierarchy levels, since the robot must be controlled in real time. Ill. 4, bibl. 13 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.298
Image Magnification Method Comparison
Authors: Vysniauskas V. , Daunys G. , Vysniauskaite K.
Published: December 2011

Different image magnification methods are related very close with each other except the simplest Box method that does not use any interpolation. All tested methods show about the same RMSE results for the same picture. Lanczos methods show the best results and simplest Box method shows the worst results. Statistically, difference between interpolation methods, is less than one percent. But, for example, Lanczos works well where intensity gradient is higher, but brings more errors when intensity changes softly. Pixels with errors surround the edges, but can cover wide areas near edges. Image noise can increase RMSE value dramatically, concurrently noise can be invisible on image and produce a little intensity ripple but have a lot of pixels and produce high RMSE value. Ill. 11, bibl. 10, tabl. 1 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.299
Quality Estimation Methodology of Speech Recognition Features
Authors: Lileikyte R. , Telksnys L.
Published: December 2011

The best feature set selection is the key of successful speech recognition system. Quality measure is needed to characterize the chosen feature set. Variety of feature quality metrics are proposed by other authors. However, no guidance is given to choose the appropriate metric. Also no metrics investigations for speech features were made. In the paper the methodology for quality estimation of speech features is presented. Metrics have to be chosen on the ground of their correlation with classification results. Linear Frequency Cepstrum (LFCC), Mel Frequency Cepstrum (MFCC), Perceptual Linear Prediction (PLP) analyses were selected for experiment. The most proper metric was chosen in combination with Dynamic Time Warping (DTW) classifier. Experimental investigation results are presented. Ill. 5, bibl. 18, tabl. 3 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.302
Method for Fast and Complexity-Reduced Asymmetric Image Compression
Authors: Bilinskis I. , Skageris A. , Sudars K.
Published: December 2011

Standartised image compression/reconstruction algorithms are symmetric in the sense that the computational complexities characterizing image compression and reconstruction stages are almost equal. An approach to assymetric image compression is suggested and discussed. Image compression performed according to this approach is extremely simple and the computational burden of the commpression/reconstruction task is shifted assymetrically to the image reconstruction stage. This approach, based on typical DASP methods, is described and discussed. The described image compression/reconstruction algorithms have been evaluated both on the basis of computer simulations and experimental studies and the obtained results are given. Ill. 2, bibl. 3 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.303
A Fully Automatic Autofocusing Algorithm for Post-processing ISAR Imaging based on Image Entropy Minimization
Authors: Kallitsis E. D. , Karakasiliotis A. V. , Boultadakis G. E. , Frangos P. V.
Published: December 2011

Autofocus is a technique for improving inverse synthetic aperture radar (ISAR) imaging. In this paper, a novel autofocusing method is developed for high-resolution stepped-frequency ISAR. Non-uniform rotational motion is compensated through the proposed post-processing methodology. In this way, the computational cost of polar reformatting process can be circumvented. The proposed CPI-split autofocusing process results in well-focused ISAR images for high angular acceleration periods. Finally, ISAR image entropy dependencies are thoroughly examined through various simulation results, leading to an acceptable range of entropy values for the autofocusing process. Ill. 7, bibl. 9, tabl. 3 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.305
Teaching of Telecommunication-Specific University Course in Cooperation with Partners from Industry
Authors: Ainomae A. , Rokk I. , Lossmann E.
Published: December 2011

Modern information and telecommunication technology (ICT) is rapidly evolving in time and there is a constant need for specialists, who have good knowledge to meet the industry needs. One way to perform industry specific knowledge transfer form industry to academia is to involve partner's specialist in teaching the courses. The aim of this paper is to introduce an example of course setup in teaching VoIP and IMS technologies for ICT students. We analyze the opportunities and limitations seen in organizing and teaching this course based on our 3-year experience. We also give some suggestions for developing the course when industry interest and support, due to the situation in economy and market, may change in time. Bibl. 3 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.306
Determination of Sensor Network Coverage using Probabilistic Approach
Authors: Gorecki J. , Miedzinski B. , Nouri H.
Published: December 2011

Paper elaborates the method to identify near and far coverage area for each sensor estimating quality of service parameters in order to assess the areas of sensor redundancy and shortage. Coverage in near area is used to identify whether single sensor is enough to cover this area (sensor shortage indicating denser sensor layout). Coverage in far area is used to identify which sensors can be removed from the field in order to have lower cost of deployment of sensor network (sensor redundancy). Ill. 3, bibl. 7, tabl. 1 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.111.5.345
Estimation of DWDM Transmission for Broadband Access with FBG Technology
Authors: Ozolins O. , Ivanovs G.
Published: December 2011

In this paper authors have measured amplitude transfer functions of FBG technology optical filters with 50 GHz and 100 GHz FWHM bandwidth and have evaluated their performance in 2.5 Gbit/s and 10 Gbit/s DWDM transmission system over a typical length of broadband access network. Reliable transmission is realized for eight channels 2.5 Gbit/s DWDM transmission system with 50 GHz FBG for 20 km of SSMF and for eight channels 10 Gbit/s DWDM transmission system with 50 GHz FBG for reduced distance (10 km of SSMF). Ill. 6, bibl. 10 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.111.5.346
Variation of Radio Refractivity with Height above Ground
Authors: Valma E. , Tamosiunaite M. , Tamosiunas S. , Tamosiuniene M. , Zilinskas M.
Published: December 2011

In Vilnius, the daily and the seasonal variations of the radio refractivity values have been computed at the Earth surface in the years 2005-2010 and at the heights up to 1.2 km in November 2010. The International Telecommunications Union - Radiocommunications Sector (ITU-R) model was used for calculation of the radio refractive index according to the peculiarities of climatic conditions of Lithuania. As a result of obtained data analysis, the days with more variable meteorological parameters have been chosen for more detailed investigation. The radio refractivity gradient has been computed at the heights starting from the Earth surface up to 1.2 km above the ground, using the meteorological data measured at those heights. The variation of radio refractivity and its gradient are influenced by the changes in air's humidity and temperature in most part. Ill. 7, bibl. 17, tabl. 1 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.111.5.349
Study of the Impact of Self-Similarity on the Network Node Traffic
Authors: Kaklauskas L. , Sakalauskas L.
Published: December 2011

The article analyses a stochastically bounded the GI/G/m//N circuit switched network model with packet losses, with stochastic input network traffic, stochastic served network node, and deterministic and finite network node buffer capacity. Max-plus algebra instrumentality is used for the network processes analysis. FIFO tail drop or LIFO tail drop buffer is used. We have established that the average waiting time in the queue had increased when the queue service discipline was FIFO as compared with LIFO, while the offered traffic was Poisson and the served in the node traffic was self-similar. The network traffic is served faster in the network node with the buffer queue discipline LIFO, while the offered traffic is Poisson and its intensity exceeds the served in the node traffic 10 times. Ill. 2, bibl. 24 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.111.5.350