Disertacijoje aprašyti šešiafazių asinchroninių variklių dinaminiai modeliai ir ištirti pereinamieji vyksmai. Disertaciją sudaro įvadas, trys pagrindiniai skyriai, išvados, naudotos literatūros ir autoriaus publikacijų disertacijos tema sąrašas. Įvadiniame skyriuje suformuluota tiriamoji problema, darbo aktualumas, tyrimų objektas, darbo tikslas ir uždaviniai, tyrimų metodika, darbo mokslinis naujumas, rezultatų praktinė reikšmė, ginamieji teiginiai. Įvado pabaigoje pristatytos autoriaus paskelbtos publikacijos disertacijos tema ir pateikiamas perskaitytų pranešimų konferencijose sąrašas bei aprašoma disertacijos sandara. Pirmame skyriuje aprašyti daugiafazių variklių privalumai lyginant juos su trifaziais ir nurodyti jų taikymo atvejai. Aprašyti šešiafazių asinchroninių variklių tipai. Pateiktas šešiafazio asinchroninio variklio matematinis modelis. Pristatyti šešiafazių asinchroninių elektros pavarų valdymo metodai. Suformuluotos skyriaus išvados ir disertacijos uždaviniai. Antrajame skyriuje pateikti šešiafazio asinchroninio variklio kompiuteriniai modeliai sukurti pagal variklio statoriaus, rotoriaus srovių ir srautų išraiškas. Aprašyti imitacinių modelių naudojimo atvejai greitojo prototipo sistemose. Skyriaus pabaigoje suformuluotos išvados. Trečiajame skyriuje pristatyti šešiafazių asinchroninių pavarų imitaciniai ir eksperimentiniai tyrimai. Sudarytos sutelktosios dvisluoksnės sutrumpinto žingsnio ir poliaus žingsnio šešiafazių apvijų schemos. Pateikti šešiafazio... [toliau žr. visą tekstą] / Dynamic models for investigation transient processes of six phase induction motors are presented in this dissertation. The thesis layout consists of introduction, three main chapters, conclusions, bibliography and list of publications. The introduction reveals the investigation problem, importance of the work and the object of research as well as describes the purpose and tasks of the paper, research methodology, scientific novelty, the practical significance of obtained results and defended statements. The author’s publications on the subject of the defended dissertation, offering the material of made presentations in conferences and the structure of the dissertation are presented at the end of introduction. The advantages of multiphase motors over conventional three phase are presented in the first chapter. The applications with multiphase motors are reviewed. The types of six phase induction motors are presented. The mathematical model of six phase induction motor are composed. The control methods of six phase induction motors are reviewed. At the end of the chapter, conclusions and tasks for the dissertation are formulated. The second chapter is dedicated for methodology to develop two types mathematical models of six phase induction motor. First of them is composed according to stator and rotor current expressions and second one according to stator and rotor flux expressions. Fast prototype systems with simulation models are reviewed. At the end of the chapter... [to full text]

Pastarųjų metų technologinė puslaidininkinių trimačių mikro struktūrų gamybos procese pažanga leidžia sukurti vis tikslesnius ir patikimesnius tokio tipo elektromechaninius jutiklius. Gerėjanti tokio tipo jutiklių kokybė atveria naujas jų panaudojimo galimybes. Vena jų – vidaus navigacinė sistema. Tokio tipo sistema reikalauja tikslių pagreičio, kampinio greičio ir kitokio tipo duomenų judėjimo trajektorijai nustatyti. Šiame darbe yra apžvelgtos pagrindinės problemos su kuriomis susiduriama kuriant inercines vidaus navigacines sistemas. Apžvelgti, patikrinti ir pasiūlyti alternatyvūs šių problemų sprendimo metodai. Mechaninių jutiklių taikymo navigacijai patalpų viduje tyrimas. Magistro baigiamasis darbas elektronikos inžinerijos magistro laipsniui. Vilniaus Gedimino technikos universitetas. 2014 m. / Recent technological improvements in micromachining process allows to produce smaller, cheaper and more accurate MEMS sensors. Better accuracy/size ratio increases MEMS sensors application field. One of most precise sensors looking for field is MEMS based indoor navigation system, which requires precise accelerometer/gyros, to ensure error free estimated position. Current gyros and accelerometers are much less precise than standard laser based gyros and bulk accelerometers. This work describes the main problems of using MEMS for inertial navigation and possible solutions, to minimize estimated position error. Research of MEMS application for indoor navigation. Master thesis for electronics engineer master degree. Vilnius Gediminas Technical University. Vilnius 2014 m.

Dažnio matavimo stendo sudarymas ir tyrimas. Magistro baigiamasis darbas elektronikos inžinerijos laipsniui. Vilniaus Gedimino technikos universitetas. Vilnius, 2014, 71 p., 31 iliustr., 3 lent., 36 bibl., 6 priedai. Sukurtas ir ištirtas dažnio matavimo stendas, atskleidžiantis skaitmeninių dažnio ir periodo matavimo būdų ypatumus. Stendas pakeis šiuo metu laboratoriniuose darbuose naudojamus pasenusius prietaisus. Stendą sudaro 3 užduodantys generatoriai, dažnio sintezatorius, dažniamatis ir sąsaja su asmeniniu kompiuteriu, bendrame korpuse. Matavimo rezultatams įvertinti sukurta specializuota programinė įranga. Atlikus stendo tyrimus įsitikinta, kad sukurtas dažniamačio stendas atitinka visus užduoties reikalavimus. / Creation and investigation of frequency counter. Master's thesis in electronics engineering degree. Vilnius Gediminas Technical University. Vilnius , 2014, 71 p., 31 pictures, 3 tables, 36 references, 6 extras. Frequency counter stand have been created and investigated. Stand will allow students to familiarize themselves with particularities of digital measurement methods of frequency and duration of the period. The new stand will replace old measurement devices that are used during laboratory works recently. The stand consists of frequency synthesizer, frequency counter, 3 different reference generators and interface to the computer packed in single case. Specialized software have been created to assess and treat measurements results. Testing results of the bench proved that created frequency counter stand meets all the requirements of the task.

In this work, a versatile electrochemical biosensing platform was developed based on graphene/zinc oxide (G/ZnO) nanocomposite. For the synthesis of G/ZnO nanocomposite, two facile and green approaches were employed to eradicate the issues associated with conventional methods, which use harsh chemicals and high temperature. The G/ZnO nanocomposite synthesised via low temperature hydrothermal growth method exhibited approximate 58 times improvement in terms of sensitivity as compared to the G/ZnO nanocomposite synthesised via the mechanical stirring method. Therefore, the G/ZnO nanocomposite with higher sensitivity was employed for the following work. Results from cyclic voltammetry and amperometry showed that the G/ZnO-modified electrode displayed a wide linear range up to 15 mM for the detection of H2O2 and sensitivity improvements of 200% in comparison to the control sample. Subsequently, an electrochemical genosensor based on G/ZnO nanocomposite was fabricated for the detection of Avian Influenza H5N1 virus. The G/ZnO-based genosensor displayed its potential in replacing the conventional detection method, with result showing higher sensitivity and efficiency. The G/ZnO-based genosensor was further applied for the detection of Coconut Cadang-Cadang Viroid disease (CCCVd) single stranded RNA (ssRNA). Promising results were obtained with high specificity in discriminating the target from mismatched ssRNA sequences.

This four-part dissertation is essentially concerned with some theoretical aspects of the stability studies of power systems with large penetration levels of distributed generation. In particular, in Parts I and II the main emphasis is placed upon the transient rotor angle and voltage stability. The remaining two parts are devoted to some system-theoretic and practical aspects of identification and modeling of aggregate power system loads, design of auxiliary robust control, and a general qualitative discussion on the impact that distributed generation has on the power systems. One of the central themes of this dissertation is the development of analytical tools for studying the dynamic properties of power systems with asynchronous generators. It appears that the use of traditional tools for nonlinear system analysis is problematic, which diverted the focus of this thesis to new analytical tools such as, for example, the Extended Invariance Principle. In the framework of the Extended Invariance Principle, new extended Lyapunov functions are developed for the investigation of transient stability of power systems with both synchronous and asynchronous generators. In most voltage stability studies, one of the most common hypotheses is the deterministic nature of the power systems, which might be inadequate in power systems with large fractions of intrinsically intermittent generation, such as, for instance, wind farms. To explicitly account for the presence of intermittent (uncertain) generation and/or stochastic consumption, this thesis presents a new method for voltage stability analysis which makes an extensive use of interval arithmetics. It is a commonly recognized fact that power system load modeling has a major impact on the dynamic behavior of the power system. To properly represent the loads in system analysis and simulations, adequate load models are needed. In many cases, one of the most reliable ways to obtain such models is to apply a system identification method. This dissertation presents new load identification methodologies which are based on the minimization of a certain prediction error. In some cases, DG can provide ancillary services by operating in a load following mode. In such a case, it is important to ensure that the distributed generator is able to accurately follow the load variations in the presence of disturbances. To enhance the load following capabilities of a solid oxide fuel plant, this thesis suggests the use of robust control. This dissertation is concluded by a general discussion on the possible impacts that large amounts of DG might have on the operation, control, and stability of electric power systems.

<p>This four-part dissertation is essentially concerned with some theoretical aspects of the stability studies of power systems with large penetration levels of distributed generation. In particular, in Parts I and II the main emphasis is placed upon the transient rotor angle and voltage stability. The remaining two parts are devoted to some system-theoretic and practical aspects of identification and modeling of aggregate power system loads, design of auxiliary robust control, and a general qualitative discussion on the impact that distributed generation has on the power systems. </p><p>One of the central themes of this dissertation is the development of analytical tools for studying the dynamic properties of power systems with asynchronous generators. It appears that the use of traditional tools for nonlinear system analysis is problematic, which diverted the focus of this thesis to new analytical tools such as, for example, the Extended Invariance Principle. In the framework of the Extended Invariance Principle, new extended Lyapunov functions are developed for the investigation of transient stability of power systems with both synchronous and asynchronous generators. In most voltage stability studies, one of the most common hypotheses is the deterministic nature of the power systems, which might be inadequate in power systems with large fractions of intrinsically intermittent generation, such as, for instance, wind farms. To explicitly account for the presence of intermittent (uncertain) generation and/or stochastic consumption, this thesis presents a new method for voltage stability analysis which makes an extensive use of interval arithmetics. </p><p>It is a commonly recognized fact that power system load modeling has a major impact on the dynamic behavior of the power system. To properly represent the loads in system analysis and simulations, adequate load models are needed. In many cases, one of the most reliable ways to obtain such models is to apply a system identification method. This dissertation presents new load identification methodologies which are based on the minimization of a certain prediction error. </p><p>In some cases, DG can provide ancillary services by operating in a load following mode. In such a case, it is important to ensure that the distributed generator is able to accurately follow the load variations in the presence of disturbances. To enhance the load following capabilities of a solid oxide fuel plant, this thesis suggests the use of robust control. This dissertation is concluded by a general discussion on the possible impacts that large amounts of DG might have on the operation, control, and stability of electric power systems.</p>

A design of a Smart Home system which is expected to help people with physical and speech impairments to control their living environment is given there. It was done during Eureka project E!2707 (PACS). Hardware and software analysis, algorithms and methods, usability test of developed system user interface are given there. A review of similar systems designed for disabled was done. Analysis of user requirements, detailed analysis and implementation ways of user interface are given there. The most popular building automation standards were analyzed and the most suitable one – Konnex association standard KNX was selected. Three different system block diagrams, software algorithm and its implementation methods were given and analyzed. A model of the user interface was created. An investigation was made. The goal of it is to evaluate the main user interface parameter – activation time which makes a better usability of the whole system.

The main aims of automatized environment of theoretical researches are to help and accelerate complicated signals' processing, creation of algorithms of neurons' networks, filters and other symbolic and calculation engineering researches which can be understood and promoted by every person. The environment has been implemented using simple as possible interaction of machine and the human communication and the possibility to actuate into research bases of systems of knowledge.

Reability of electric device is examined in diploma work engineer’s degree. It is written about classification in reability, in incorruptibility rate. It is researched in accidents, causability of accidents in Lithuania. One question – what should we do to make less accidents. One of solution is to use safety and reability electric devices. Data of accident in Lithuania is used, which happened till the 5th of may 2003 year. Conclusion and recommendation – do not economize to safety and reability electrical device.

Aim of the work 1. To suggest the techniques, which allow detecting already known virus epidemics of the telecommunication nets and unknown ones effectively. 2. To calibrate the efficiency of the technique behaviour.