In the present study, there was performed a research of safety parameters of electrical devices, there were performed various measurements and calculations, comparisons of received results, considered problems, associated with these parameters. There was considered condition of equipment before and after repairs.. Proposed suggestions regarding installation of unconventional devices as well as calculating during the process of design, there was described a research of dependence of resistances of grounders on deepening in earth, performing measurements. Also, upon selection of calculation methodology, there were performed calculations of grounded resistances. The results of calculations were compared with the measured ones. There was touched on a subject of solution of some problems of grounder installation - i.e. installation of unconventional grounder. There was provided the method of installation of such grounder, peculiarities of its equipment. There were analysed results of measurement of screws, they were compared with the results of conventional grounders. There was developed the methodology of calculations of grounders and there was provided data of calculations as well as comparison with the measured ones. There was described application of this method as well as its benefit and advantages. There were considered peculiarities of results of measurement of resistances of transitive contacts, positioned in chemically aggressive environment. There was analysed the... [to full text]

Masters diploma The purpose of the masters diploma work is analysis of efficiency of hydrogen power stations. Based on the data collected in the work, current exploration directions in hydrogen energetic and kinds of fuel cells can be reviewed, as well as results of a laboratory tests, performed with laboratory fuel specimens. Hydrogen power station, as a station of the future, is currently in the developing phase. Fuel cell and solar panel battery types and efficiency factors are examined, considering fuel cells and solar panel batteries, as primary supply source, are major components in the power station. The most important thing in operation of the power station is it‘s rate of efficiency. The attempt will be made to determine common efficiency value of such power station. It will be possible to compare received results with those provided in the specified literature.

In this thesis are investigated lighting control systems, peculiarities of lighting systems, classification, requests, counting methods. There are given a lot of information about daylight and illumination, in analytical part. In reference with illumination values, given in the hygiene norms, there are calculated the number of illuminators in the room. Lighting control systems efficiency is investigated by comparison manual lighning control with automatic. In this thesis are investigated, how many power we lose, when selecting manual control system instead of automatic control system with digital devices. According to results of experiment, there are made characteristic of power deppencies on illumination. Conclusions are formulated at the end of a transaction.

The analysis of logic device characterization have been performed. Logic device sorts and its characterization analysis was made. The analysis of other logic device test system was performed. The logic test system requirements was made. The hardware project of logic device test system and system hardware mounting was made. The software for the logic device test system was made. Experimentation of logic device test system was performed. The results of experimentation was given. Graphs about logic test system analysis of trustiness research was given. Performed finding about the logic device test system accordance for technical requirements, trustiness and universality.

Aim and tasks of the work. The aim of this work is to investigate insufficiently analyzed variants of the electrodynamic super-wide-band slow-wave structures, create their models, improve methods of analysis, analyze properties of the systems and reveal potentiality of the traveling-wave cathode-ray tubes, slow-wave structures. In order to achieve the aim it is necessary: 1. To improve method for evaluation of non-linear distortions in the traveling-wave cathode-ray tubes and reveal possibilities of reduction of non-linear distortions. 2. To create models of the insufficiently analyzed variants of slow-wave structures and reveal properties of the slow-wave structures. 3. To reveal influence of periodical non-homogeneities on properties of slow-wave structures, simulate and reveal influence of transitions to properties of slow-wave structures and traveling-wav cathode-ray tubes. 4. To make investigation of potentiality of slow-wave structures and traveling-wave cathode-ray tubes and select variants of slow-wave structures that can guarantee wide band and high operating speed of the traveling-wave cathode-ray tubes. Scientific novelty and practical value. Models of insufficiently simulated slow-wave structures were created and their properties were analyzed. According to analysis and modeling results, variants of systems were selected that can guarantee the wide pass-band and high operating speed of the traveling-wave cathode-ray tubes. Using finite element method calculation... [to full text]

Aim and tasks of the work. The aim of this work is to investigate insufficiently analyzed variants of the electrodynamic super-wide-band slow-wave structures, create their models, improve methods of analysis, analyze properties of the systems and reveal potentiality of the traveling-wave cathode-ray tubes, slow-wave structures. In order to achieve the aim it is necessary: 1. To improve method for evaluation of non-linear distortions in the traveling-wave cathode-ray tubes and reveal possibilities of reduction of non-linear distortions. 2. To create models of the insufficiently analyzed variants of slow-wave structures and reveal properties of the slow-wave structures. 3. To reveal influence of periodical non-homogeneities on properties of slow-wave structures, simulate and reveal influence of transitions to properties of slow-wave structures and traveling-wav cathode-ray tubes. 4. To make investigation of potentiality of slow-wave structures and traveling-wave cathode-ray tubes and select variants of slow-wave structures that can guarantee wide band and high operating speed of the traveling-wave cathode-ray tubes. Scientific novelty and practical value. Models of insufficiently simulated slow-wave structures were created and their properties were analyzed. According to analysis and modeling results, variants of systems were selected that can guarantee the wide pass-band and high operating speed of the traveling-wave cathode-ray tubes. Using finite element method calculation... [to full text]

Topicality of the problem. Wireless WAN technologies which can provide multimedia services to customer in most cases are implemented by the commercial providers of voice services. Thus technologies are expensive in development of the Hot-Spots, where volatile expanded concentration of customers may be observed. For such purposes the main alternative technologies are the IEEE 802.11. In modern telecommunications industry the expansion of the IEEE 802.11 networks is one of the fastest growing segment of the telecommunications market. This technology has quickly found a significant place and popularity to provide the typical services of Internet in business, home networking, and etc. Growing evolution of Internet technologies determines transmitted data flows to take a shape of specific real time multimedia flows features. For such conditions the IEEE 802.11 general technology was not adapted. It is important to develop the new operation methods based on IEEE 802.11 without changing main standard specification. This method lets to adopt an existing in market equipment of IEEE 802.11 for multimedia or voice flows. The methodology of IEEE 802.11 technological expenditures influence estimation, presented in dissertation, has not been used before. This estimation method allows to evaluate rationality of physical resource utilization and to predict protocol modification directions. Also, method of synchronous voice communication in customer access is proposed. This solution allows... [to full text] / Mokslo problemos aktualumas. Plačiajuostės licencijuojamų dažnių bevielės technologijos, kurios paprastai skirtos vartotojams teikti komercines multimedijos ir balso paslaugas, yra per brangios vystant prieigos tinklus, kuriuose sutinkama didelė vartotojų koncentracija. Dėl to šios technologijos dažniausiai naudojamos tik komercinių balso paslaugų tiekėjų. Labiausiai tinkama alternatyva – yra IEEE 802.11 technologijos, kurių naudojimas modernių telekomunikacijų tinklų išplėtimui įvairiose tipinėse sąlygose yra pastebimai auganti telekomunikacijų rinkos dalis. Ši technologija greitai išplito ir tapo populiari verslo, namų, „paskutinės mylios“ ir kituose tinklų vystymo sprendimuose. Modernėjant Interneto technologijoms, telekomunikacijų tinkluose įsivyrauja multimedijos požymių turintys srautai, kurių sukurtoms specifinėms sąlygoms IEEE 802.11 technologijos nėra pritaikytos. Todėl svarbu kurti naujus, ribines galimybes išnaudojančius, bet specifikacijos nekeičiančius protokolus, kurie leistų rinkoje esančią įrangą adaptuoti realaus laiko srautams. Disertacijoje naudojama IEEE 802.11 MAC protokolo technologinių sąnaudų įtakos vertinimo metodika nebuvo taikoma. Šis vertinimo būdas leidžia įvertinti fizinio resurso užėmimo racionalumą ir numatyti IEEE 802.11 protokolo modifikavimo kryptis. Pateiktas sinchroninis vartotojų prieigos adaptacijos balso perdavimams būdas leidžia racionaliai panaudoti IEEE 802.11 protokolą balsui adaptuotose vartotojų prieigose. Todėl, galima teigti... [toliau žr. visą tekstą]

Disertacijoje nagrinėjamos medicininių vaizdų analizės problemos, taikant vaizdų spektrus. Pagrindiniai tyrimo objektai yra galvos kompiuterinės tomogramos bei magnetinio rezonanso angiogramos. Šie objektai yra svarb��s medicininės diagnostikos rezultatai, kurių detali analizė bei interpretacija leidžia parinkti tinkamiausią paciento gydymo būdą. Pagrindinis disertacijos tikslas yra sukurti metodikas ir algoritmus, skirtus automatiniam min÷tų vaizdų apdorojimui bei analizei. Sukurtų algoritmų taikymo sritis yra medicininė programinė įranga. Taip pat disertacijoje siekiama ištirti dažninio ir erdvinio dažninio spektrų taikymo galimybes medicininių vaizdų apdorojime ir analizėje, siekiant aptikti ir pažymėti vaizduose ligų sritis arba kitas specifines sritis. Darbe sprendžiami keli pagrindiniai uždaviniai: smegenų ir išeminio insulto sričių aptikimas tomogramose bei kraujagyslių pėdsakų sričių aptikimas angiogramose. Pirmasis uždavinys suformuluotas, atsižvelgiant į palyginti didelį išeminio insulto paplitimą ir jo diagnostikos aktualumą. Antrasis siejasi su aneurizmos srities aptikimo angiogramose problema. Disertaciją sudaro šeši skyriai, iš kurių paskutinis – rezultatų apibendrinimas. / The main idea of current PhD thesis is an analysis of frequency and joint space-frequency representations of medical images. The objects of investigation are digital images of computed tomography and magnetic resonance angiography of human brain. These objects are essential diagnostic results which require a detail visual analysis and interpretation for the successive selection of treatment. The aim of work covers the development of methods and algorithms suitable for automatic analysis of medical images which may be implemented in medical software. The other purpose encompasses an investigation of Fourier and Haar wavelet transforms in the analysis and processing of medical images. The result of analysis is assumed as an enhancement and segmentation of suspected regions of diseases or other specific regions. There are two main tasks under consideration. First one is an automatic detection of region of brain and ischemic stroke in the images of computed tomography. Second one is a detection of traces of blood vessels in magnetic resonance angiography images. The first task is formulated in the view of wide distribution and high relevance of diagnosis of ischemic stroke. Second task is related with the detection of diseases of blood vessels. The thesis is divided into six chapters including the conclusion’s chapter.

Vaizdo kontūrų nustatymo metodų tyrimui buvo pasirinktas 100 įvairaus turinio paveikslų su įvairiu elementų dydžiu ir skaičiumi. Tyrimui buvo pasirinkti 8 populiariausi vaizdo kontūrų nustatymo metodai: Canny, Sobel, Prewitt, Roberts, Zerocross, Laplacian, LoG, Marr-Hildreth. Atliekant tyrimus visiems paveikslams, naudojant visus 8 metodus, buvo subjektyviai parinkta optimaliausia slenkstinė reikšmė. Gavus visų 100 įvairių paveikslų geriausias slenkstines reikšmes su visais 8 metodais, buvo nustatytos slenkstinių reikšmių kitimo ribos kiekvienam kontūro išskyrimo metodui. Kiekvienam paveikslui buvo pritaikyta vidutiniškai 10 slenkstinių reikšmių ir kiekvienam paveikslui buvo suskaičiuotas vidutinis kvadratinis nuokrypis (RMSE, Root Mean Square Error) su geriausiu pasirinktu kontūru. / One hundred various pictures with different size and number of elements were chosen for the method research of image outline evaluation. All these pictures were converted into grayscale pictures. Most of edge detection methods (filters) required to be blurred to reduce noise. Eight the most popular methods were chosen to evaluate the image outline: Canny, Sobel, Prewitt, Roberts, Zerocross, Laplacian, LoG, Marr-Hildreth. A Root Mean Square Error (RMSE) was computed for each edge picture with the best-chosen outline.

Vystantis technologijoms, prieš apytiksliai aštuonerius metus buvo už patentuota nauja tinklo rūšis - bevielis tinklas. Pastebėjus jų privalumus buvo pradėti sparčiai vystyti . Sparčiai jiems populiarėjant išryškėjo kolizijos problema.Siekiant daugiau apie tai sužinoti buvo iškeltas darbo tikslas - išnagrinėti kolizines situacijas, pateikiant jų pasekmes, vengimo galimybes.Siekiant šio tikslo išnagrinėti populiariausi tinklų tipai. Eksperimentiškai įvykdytos dvi populiariausios kolizinės situacijos. Apžvelgti jau taikomi, bei taikytini, kolizinių situacijų vengimo būdai. Atlikus visas išsikeltas užduotis prieita prie išvados: Norint sumažinti kolizijų kiekį, pagerinti tinklo pralaidumą, pratęsti mobilaus prietaiso energijos šaltinio gyvavimo laiką (energijos suvartojimo kiekį) siūlau „paskleisti“ vartotojus (sudarinėti kiek į manoma mažiau vartotojų turinčius tinklus).Pvz. nagrinėtame WLAN centralizuotos tipologijos koliziniame atvejyje, reikia išdėstyti daugiau kreipties taškų AP. Taip būtų mažinamas vartotojų kiekis vienam AP. Bluetooth „ad hoc“ tipologijai, turint kitokią struktūrą , šis pasiūlymas tiktų turint ne mažiau kaip tris vienu laiko momentu aktyvius prietaisus. / By developing the technologies, approximately eight ears ago a new way of network where found and patented – wireless network. After seeing the advantages of these networks, they started fast development. As wireless network started to be more and more popular a problem of collisions in it started to give more concern. In order to know more about collisions and the way of collision appearance, the task of thesis was to – inspect the situations of collision, bring out the consequences, possible avoidance of it. Seeing this goal most of popular wireless networks where investigated. Reasons of collisions, experimentally explored situations for collisions, possibilities of resolving it where reviewed. After doing all this work, it can be concluded: To lower possible collision rate, ensure better throughput, make longer life time to mobile station (save energy) spreading of users (make smaller networks, with lower quantity of mobile users) might be a way. For example: in case of collision in analyzed WLAN central topology, we would need to add extra access points. That‘s would lower quantity of users per AP. Bluetooth „ad hoc“ topology is different in structure so this proposal would be valid just when minimum three active devices are in a range.