The object of the thesis was to develop a simple method of the ADC quality evaluation of computer audio systems, which does not require a special apparatus, and software for its realization. To correct the ADC ENOB measurement methodology recommended in the IEEE Std 1241-2000. By applying the recommended method, to investigate possibilities of formation and application of new test analog signals for ADC investigation. To show the possibilities of untraditional computer audio systems application for measurements.

In this thesis is investigated how magnetic field varies at different instants of time in the air gap of linear induction motor and outside of it. The are given results of simulation, which show the change of magnetic flux at different instants of time of linear induction motor in the air gap, outside the inductors, also magnetic flux dependencies on air gap width. Two models of linear induction motor with secondary element and without it are compared.

Šiame darbe nagrinėjami žmogaus akių judesiai internetinuose puslapiuose. Stengiamasi išsiaiškinti ar puslapio tipas, ar individualus žmogaus veiksniai, nulemia tinklapio peržiuros procesus, kas patraukia dėmesį labiausiai ir ko neneužfiksuoja akis apsilankius pirmą kartą internetiniame puslapyje. Nagrinėjamas sakadinis akių judesių tipas, kai žvilgsnį žmogus perkelia nuo vieno fiksacijos taško į kitą. Naudojamas fiksacijų skaičius, laikas ir ju vidutinės reikšmės. / In this study were researched eyes movements on Internet webpages. The webpage type and individual person actions were researched as an influence on the webpage view processes. Also what attracts attention the most and what objects are not traced by eye visiting the webpage on the first time. Researched sacade type of eye tracking when the look is moving from one fixation point to another. Were researched using fixation number, time and the averages of these values.

Signalų technologijų magistro darbo tema yra aktuali, nes nebepakanka įprastų informacijos įvedimo priemonių. Todėl ieškoti ir apdoroti informaciją, valdyti sudėtingus įrenginius ir programas daug patogiau būtų jei kompiuteriai ir įvairūs įrenginiai suprastų žmogaus kalbą. Pasaulyje panašios sistemos kuriamos jau daugelį metų. Tačiau šiuo metu lietuvių kalbos atpažinimo sistemos yra dar tik kūrimo stadijoje. Darbe nagrinėjamas Lietuvių kalbos žodžių atpažinimas skirstant juos į kategorijas ir naudojant paslėptuosius markovo modelius. Šio tyrimo tikslas – ištirti lietuvių kalbos žodžių skirstymo į kategorijas įtaką atpažinimo tikslumui.Taip pat tiriamas žodžių grupių bei pavienių žodžių atpažinimas. Akustinis modelis sukurtas su HTK paketu, kuris naudojasi paslėptųjų Markovo modelių metodika. Žodžių skirstymas į kategorijas aprašytas Backus-Naur formatu. Eksperimentai bus atliekami ir rezultatai gaunami naudojant, Julius programinės įrangos įrankius bei šio paketo, žodžių kategorijų pagrindu veikiančią, Julian kalbos atpažinimo sistemą. Geriausi rezultatai gauti bandant atpažinti pavienius žodžius suskirstytus į kategorijas. Atpažinimo tikslumas siekia 91 %. Bandant atpažinti žodžių sekas, nesuskirstytas į kategorijas, gautas atpažinimo tikslumas tesiekia 51 %. Microsoft Office Word 2003 meniu valdymo atpažinimo tikslumas siekia 82 %. / The theme of Master project of signal technology is actual, because not enough usual information introduction ways. Therefore information search and processing, complicated devices and programs control would be more handily if computers and devices understood human speech. Similar systems are designing for many years in the world. However Lithuanian speech recognition systems are still developing in nowadays. The thesis treats of isolated Lithuanian words recognition dividing them into category and using Hidden Markov Models. The idea of research is to explore categorization of Lithuanian words influence on the accuracy of recognition. The recognition of single words and word groups is under research too. Acoustic model is constructed by using HTK toolkit which is based on Hidden Markov Models. Categorization of words is described with Backus-Naur form. Experiments are made with Julius software speech recognition system Julian witch performs words category based recognition. Best results are got trying to recognize single words set into categories. The accuracy rate of recognition reaches 91 %. While trying to recognize uncategorized word sequences – the accuracy rate of recognition reaches only 51 %. The accuracy rate of Microsoft Office Word 2003 control menu recognition reaches 82 %.

Modern methods of speech synthesis are not suitable for restoration of song signals due to lack of vitality and intonation in the resulted sounds. The aim of presented work is to synthesize melismas met in Lithuanian folk songs, by applying Artificial Neural Networks. An analytical survey of rather a widespread literature is presented. First classification and comprehensive discussion of melismas are given. The theory of dynamic systems which will make the basis for studying melismas is presented and finally the relationship for modeling a melisma with nonlinear and dynamic systems is outlined. Investigation of the most widely used Linear Prediction Coding method and possibilities of its improvement. The modification of original Linear Prediction method based on dynamic LPC frame positioning is proposed. On its basis, the new melisma synthesis technique is presented.Developed flexible generalized melisma model, based on two Artificial Neural Networks – a Multilayer Perceptron and Adaline – as well as on two network training algorithms – Levenberg- Marquardt and the Least Squares error minimization – is presented. Moreover, original mathematical models of Fortis, Gruppett, Mordent and Trill are created, fit for synthesizing melismas, and their minimal sizes are proposed. The last chapter concerns experimental investigation, using over 500 melisma records, and corroborates application of the new mathematical models to melisma synthesis of one [ ...].

The most widely used variable reluctance and permanent magnet stepper motors of different design types are discussed in the theoretical part of this work. It also overviews a constructional diversity of these motors, the fundamentals of operating modes and characteristics. This part discuses features of stepper motors as a part of automation control system, presents the main counting equations and applications with stepper motors. The practical part includes the mathematical model of stepper motor and the Simulink model that was developed for software package “Matlab”. Those models formed the basis for analysis of stepper motor dynamic characteristics in various operating modes (wave drive, full step drive, half step drive, microstepping, reversing, braking).

In the final dissertation you will find analyzed the two - mass electromechanical system, finite tightness shaft and non-linear mechanical link included. Explored system shaft has finite tightness, non-linear element - backlash between the parts of mechanical link. The researches of two - mass electromechanical system were made using Simulink program pack. In this paper I have made the structural system scheme, transmission functions and simulated process of two - mass dynamical system. Gained motor and outlet shaft angular rotation speed and motor's electromagnetic moment transitive process curves, by all tightness and backlash worth' s. Researched results give new information about the two - mass electromechanical system' s dynamical process.

Asimetrinė fazinių įtampų sistema stipriai pablogina asinchroninių variklių darbą. Tyrimo tikslas – ištirti trifazio asinchroninio variklio darbą, esant įvairioms maitinimo įtampos fazorių modulių asimetrijoms. Asinchroninio variklio visi energetiniai rodikliai apskaičiuoti atlikus jų tuščiosios veikos ir apkrovos bandymus bei panaudojus atskirų galios nuostolių metodą. Įtampos asimetriškumo lygis gaunamas panaudojus simetrinių dedamųjų metodą. Atsiradus asimetrijai, asinchroninio variklio oro tarpe kuriamas elipsinis sukamasis magnetinis laukas, kuris sukelia variklyje ir sukimo, ir stabdymo momentus. Tik esant simetrinei fazinių įtampų sistemai (ka = 0 %), prie variklio nurodytosios apkrovos visi kiti dydžiai gaunami nurodytieji. Teoriškai ir eksperimentiškai ištyrus 1,1 kW galios asincroninį elektros variklį gauta, kad esant asimetrinei fazinių įtampų sistemai (ka = 11 %), prie nurodytosios apkrovos asinchroninio variklio iš tinklo vartojama galia P1 padidėjo 22,4 %, apsisukimai n sumažėjo, o slydimas s padidėjo 94,7 %, galios nuostoliai ΣP padidėjo 101 %, elektromagnetinis momentas Mem padidėjo 4,9 %, naudingumo koeficientas η sumažėjo 21,4 % ir galios koeficientas cos φ sumažėjo 0,9 %. / Asymmetrical phase system of voltages significantly degrades induction motors work. The study objective - to explore the three-phase asynchronous motor at different power supply modules vector asymmetry. All energetic indicators of the asynchronous motor winding were calculated after performing their no-load and load testing, and using the method of separate power loss. Asymmetry voltage level obtained by using the method of symmetrical components. The emergence of asymmetry in the induction motor air gap created elliptical rotary magnetic field, which caused an engine torque and braking points. Only a symmetrical phase voltage system (ka = 0%), the given load on the engine all the other values given are obtained. Theoretical and experimental study of 1,1 kW electric asynchronous motor revealed that in asymmetric phase voltage system (ka = 11%), at the given induction motor load from the mains power is used in P1 increased by 22,4%, n speed decreased and the slip increased by 94,7%, power ΣP loss has increased 101%, the electromagnetic torque Mem increased by 4,9%, the efficiency η decreased 21,4% and power factor cos φ decreased by 0,9%.

This master thesis deals with the virtual gate position and liquid level control system. The main characteristics of automatic control systems, fuzzy logic systems, their properties and formation principles are reviewed. Conventional and advanced control methods are presented pointing out their benefits, drawbacks and problems to be solved. Physical modelling and simulation issues are also discussed. Physical, mathematical, simulation and animation models of the system are produced. Position and level controllers are designed. The simulation of gate position and liquid level control processes is performed. The simulation model is built up using MATLAB Simulink and Fuzzy Logic Toolbox. The simulation results prove that the proportional controller fits very well for controlling gate position. However, the results of liquid level control “upwards” using PI controller are only satisfactory. Unsatisfactory results are obtained using the same controller for liquid level control “downwards”. Substantially better results are achieved using fuzzy logic controller. The models produced can be useful for further investigations and learning purposes.

Analysis of electromagnetic stepper motor at work have been performed. Types of stepper motors and its characteristics have been described generally. The programmes of modelling have been searching using internet and analysed. The programme QuickField 5.2 Studen‘s edition is in consort to demands and requests. Using QuickField 5.2 Student‘s edition the model of electromagnetic motor have been created and experimentations have been performed. Varying displacement of motor magnetic part the distribution of magnetic flux density and magnetic field lines have been analysed. The experimentations involving change of motors mechanical characteristics too (varying air gap between magnetic circuit and secondary part). Teoretical characteristics of distribution of magnetic field energy density, strenth and magnetic flux have been maked and compared. The conclusions and theoretical results specifying operating principle facility of electromagnetic motor. Characteristics of distribution of magnetic field and energy can be used for rating of influence to operation of motor.