This thesis deals with experimental measurement of angular distribution of electromagnetic radiation scattered from solar cells surfaces. The measuring apparatus is the second genaration of a scattermeter. This apparatus has been put into operation within the framework of this thesis. Results of the thesis are materials for numerical simulations aforementioned scattering and quantitative evaluation of scattering of electromagnetic waves from given surfaces.

Tato práce se zabývá optimalizací procedury měření optického záření rozptýleného pevnými tělesy prováděného pomocí scatterometru. V práci je popsáno několik metod použitelných k nalezení souboru pozic nepřekrývajících se kruhových detektorů na povrchu polokoule (i koule). Výsledky práce jsou aplikovány na samotný meřicí přístroj a je ukázána shoda experimentálních výsledku získaných před i po optimalizaci. Výhodu nového uspořádání lze nalézt především v převedení dřívejšího způsobu měření na soubor nezávislých měření, což má význam pro matematické zpracování výsledků.

Study of light rays (light world lines) plays a significant role in many of astro- physical applications. Light rays are mainly studied in terms of so-called grav- itational lensing. However, the majority of studies are mainly focused on light propagation in vacuum. If the refractive and dispersive medium characterised by refractive index n is considered, effects occurring due to the medium presence need to be taken into account, which significantly complicates the problem. In the present thesis, rays propagating through simple refractive and dispersive systems, such as plane differentially sheared medium, are studied. In order to simplify the problem, the Hamiltonian equations of motion are used. The ray trajectories in the vicinity of Kerr black hole as well as accessible regions for the rays are also studied. Radial variation of the medium velocity is considered. Due to the recent increase of publications focused on the gravitational lensing in plasma, a detailed review summarizing the results obtained recently is included. 1

The Finite Element Method (FEM) is a powerful numerical method to solve wave propagation problems for open-region electromagnetic radiation/scattering problems involving objects with arbitrary geometry and constitutive parameters. In high-frequency applications, the FEM requires an electrically large computational domain, implying a large number of unknowns, such that the numerical solution of the problem is not feasible even on state-of-the-art computers. An appealing way to solve a large FEM problem is to employ a Domain Decomposition Method (DDM) that allows the decomposition of a large problem into several coupled subproblems which can be solved independently, thus reducing considerably the memory storage requirements. In this thesis, two new domain decomposition algorithms (FB-DDM and ILF-DDM) are implemented for the finite element solution of electromagnetic radiation/scattering problems. For this purpose, a nodal FEM code (FEMS2D) employing triangular elements and a vector FEM code (FEMS3D) employing tetrahedral edge elements have been developed for 2D and 3D problems, respectively. The unbounded domain of the radiation/scattering problem, as well as the boundaries of the subdomains in the DDMs, are truncated by the Perfectly Matched Layer (PML) absorber. The PML is implemented using two new approaches: Locally-conformal PML and Multi-center PML. These approaches are based on a locally-defined complex coordinate transformation which makes possible to handle challenging PML geometries, especially with curvature discontinuities. In order to implement these PML methods, we also introduce the concept of complex space FEM using elements with complex nodal coordinates. The performances of the DDMs and the PML methods are investigated numerically in several applications.

Baigiamajame magistro darbe, analitinėje dalyje, pateikta žinomi radiolokatorių antenų elektromagnetinio spinduliavimo kryptinių diagramų matavimo būdai bei svarbiausios matavimo sistemos dalies – imtuvo projektavimo teorija. Eksperimentinėje magistro darbo dalyje panagrinėti būsimi kryptinių diagramų nustatymo būdai, vienas iš jų - panaudojant elektromagnetinių bangų išsibarstymą ore. Pagal žinomus duomenis apie šį efektą sudaryta nauja alternatyvi sistema, kuri leidžia pagreitinti, sumažinti laiko bei materialines sąnaudas atliekant periodinius kryptinių diagramų matavimus ir pateiktos bendros išvados ir rekomendacijos. Darbą sudaro 7 dalys: įvadas, pagrindinės radiolokacinių sistemų techninės charakteristikos, elektroninė matavimo technika, RLS kryptinių diagramų matavimo būdai, bendros išvados ir rekomendacijos, literatūros sąrašas, priedai. / Already known Antennas Radiation Pattern Measuring Systems and theoretical Knowledge, that will help design most important part (Receiver) of measuring system, are presented In my Analysis Part of Master Work. In Experimental part there are new, that still aren’t in practical measuring used, Antennas Radiation Pattern Measuring Systems investigated. One of them is using electromagnetic Wave Scattering from Particles in the Air. Regarding all available Data’s about that effect I made System that allows us to decrease Antenna’s radiation pattern measuring time and expenses. Also made and presented some Advantages, Recommendations and Conclusions. In Master Work is 7 Parts: Introduction, Basic Radiolocation Systems technical Characteristics, Measuring Technique, Radiolocation Systems Antennas radiation patterns Measuring Methods, Conclusions, References, Supplement.

Baigiamojo darbo tikslas – radiolokatoriaus elektromagnetinio spinduliavimo srauto tankio skaičiavimas bei analizė, remiantis Europos Sąjungos bei Lietuvos higienos normomis impulsiniams elektromagnetinės spinduliuotės šaltiniams. Skaičiavimo ypatybė ta, kad atsižvelgiama į reljefo įtaką srauto kitimui erdvėje. Tyrimui naudojama Matlab duomenų analizės programa suteikia galimybę gauti maksimalų tikslumą bei ištirti galimą antenos aukščio mažinimą, neviršijant higienos normoje nustatyto 10µW/cm2 vidutinio elektromagnetinio srauto tankio vertės 1,5 m aukštyje gyvenamojoje zonoje. Parašytas programos kodas leidžia analizuoti bet kokio reljefo įtaką pasirinkto radiolokatoriaus spinduliavimo parametrams. Rezultatuose pateikiami dvimačiai bei trimačiai grafikai kaip pagrindą naudojant Palangos oro uosto teritorijos išplanavimą, taip pat skaičiavimai menamam reljefui bei esant skirtingiems antenos aukščio parametrams. Magistriniame darbe nustatyta, kad tiriamo radiolokatoriaus darbo zona atitinka higienos normas net ir sumažinus anteną iki minimalaus aukščio. Aptariami spinduliavimo mažinimo būdai, alternatyvių sistemų galimybė. / The object of this thesis is evaluation and analysis of spatial radar electromagnetic radiation density with reference to EU and Lithuania Hygiene Norm for pulse electromagnetic wave emitters. Relief influence on spatial electromagnetic radiation density distribution is taken into account. Calculations and analysis are processed using Matlab data analysis program and allows to upscale the precision and manipulate antenna height to reach its minimum value without exceeding 10μW/cm2 radiation density for inhabited area at a height of 1,5m as directed by Hygiene Norm. Written Matlab script enables to analyze various relief influence on a range of radar performance. Results are produced in the form of two and three dimensional charts having Palanga airport area as a base for building layout as well as the results for artificial relief including variable height of antenna. Results brought the conclusion of analyzed radar to be well ahead of the Hygiene Norm even with the minimum antenna height. Possible methods of minimizing radiation are explained in conjunction with new alternative aircraft detection systems being introduced.

Η ερευνητική εργασία που ακολουθεί, έχει σαν στόχο, σε πρώτο επίπεδο, να μελετήσει τα διάφορα μοντέλα ηλεκτρομαγνητικής διάδοσης και σε δεύτερο πλάνο, να δωθεί μία εικόνα σχετικά με τις επιπτώσεις της μη ιονίζουσας ακτινοβολίας, που εκπέμπεται από κεραίες και ασύρματα δίκτυα, στον άνθρωπο και στον περιβάλλοντα χώρο. Στα πρώτα κεφάλαια γίνεται μία θεωρητική αναφορά στις βασικές έννοιες της ηλεκτρομαγνητικής ακτινοβολίας και στους μηχανισμούς διάδοσης της, αλλά και στις επιπτώσεις της ακτινοβολίας αυτής στον άνθρωπο. Ακολουθεί, εκτενής παρουσίαση των πιο σημαντικών θεωρητικών μοντέλων διάδοσης ραδιοσήματος εξωτερικών και εσωτερικών χώρων αντίστοιχα. Στη συνέχεια, δίνεται λεπτομερής περιγραφή των πεδιομέτρων που χρησιμοποιήθηκαν για την καταγραφή των μετρήσεων σε διάφορες περιοχές ενδιαφέροντος. Στο τελευταίο κεφάλαιο, γίνεται παρουσίαση των μετρήσεων με συγκριτικά διαγράμματα καθώς και αναφορά για το κατά πόσο οι μετρήσεις βρίσκονται εντός των ορίων ασφαλείας που τίθενται από διεθνείς οργανισμούς. / In the present work, were studied the models of the radio signal distribution at open and close area and the consequences of the non-ionized radiation, which emits from a wide variety of wirelesses systems, on human body. Initially, the basic significances of the electromagnetic radiation, the Maxwell’s equations and the mechanics of RF distribution, were shortly presented. Further emphasis at the models of the radio signal distribution, at open and close area, was given. The consequences of the electromagnetic radiation concerning basic factors of thermal and no-thermal effect were presented. An additional report of the RF safety limits, according to various international organizations, was given. For the experimental process, we used the Narda Broadband Field meter, which recorded all the frequencies of the electromagnetic spectrum and a laptop with a suitable software (NETSTUMBLER 0.40), which allows the operator of the laptop to know the exact received power coming from the specific router of the WLAN, excluding all other signals even if they belong to the same frequency of 2.4 GHz. The comparison of the experimental measurements with the theoretical, reveals the potential of each theoretical model. Furthermore, we came to the conclusion that the experiments are in the limits of RF safety.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The Square Kilometre Array (SKA) is an international project to build the world’s largest and most sensitive radio telescope interferometer. It will consist of thousands of antennas distributed over many kilometers, with the hosting country being either South Africa or Australia. Various pathfinders have been initiated to demonstrate the technologies needed to implement the SKA. The astronomy community has defined five Key Science Projects (KSP), which are the drivers for the SKA. The science goals determine the technical requirements needed to design SKA systems. Many years of planning and development are still needed in order to meet to the requirements of such a large and complex project. This thesis aims to present the various SKA pathfinder systems in terms of their application to the SKA key science projects, with main focus that of pulsar observations. In order to achieve this, a thorough overview of basic radio astronomy principles and techniques is presented, followed by a detailed look at the various pathfinders. Throughout the work, aspects of pulsar observations are given particular attention with the goal of designing optimal systems for the SKA. / AFRIKAANSE OPSOMMING: Die Square Kilometre Array (SKA) is ’n internasionale projek om die wêreld se grootste en mees sensitiewe radio teleskoop interferometer te bou. Dit sal bestaan uit duisende antennas versprei oor etlike kilometers, met die gasheer land óf Suid-Afrika óf Australië. Verskeie koersbepalers is geïnisieer om die tegnologie te demonstreer wat benodig is om die SKA te implementeer. Die astronomie gemeenskap het vyf sleutel wetenskap projekte (KSP) gedefinieër wat dien as die drywers vir die SKA. Die wetenskap doelwitte bepaal die tegniese vereistes wat nodig is om SKA stelsels to ontwerp. Talle jare van beplanning en ontwikkeling word steeds benodig om te voldoen aan die vereistes van so ’n groot en komplekse projek. Hierdie tesis het ten doel die aanbieding van verskeie SKA koersbepaler stelsels in terme van hulle aanwending tot die SKA sleutel wetenskap projekte, met hoof fokus op die van pulsar waarnemings. Om dit te behaal, word ’n deeglike oorsig van basiese radio astronomie beginsels en tegnieke aangebied, gevolg deur ’n gedetailleerde kyk na die verskeie koersbepalers. Regdeur die werk word spesifieke aandag gegee aan aspekte van pulsar waarnemings met die doel om optimale stelsels vir die SKA te ontwerp.

Made available in DSpace on 2014-10-09T12:38:21Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:07Z (GMT). No. of bitstreams: 1 05678.pdf: 6012797 bytes, checksum: fe9d7fe0fee771d558f91a7bffb7cfa3 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The phantoms used in Brazil are mostly imported and have relatively high financial cost. Although these phantoms can be considered as essentials for use in quality control, probably high quotas and import bureaucracy are obstacles to their acquisition by the nuclear medicine departments. The main objective of this work was the development of national phantoms for use in quality control of scintillation cameras used in nuclear medicine and for training professional personnel. Initially, we sought to know the interest of medical physicists and radiation protection supervisors in the acquisition of phantoms. After that, it was initiated the construction of three distinct types of physical phantoms, the SENCOR, to evaluate the sensitivity and the center of rotation; the SIMUFÍGADO, which is a liver phantom; and the ANTROFÍGADO, which is an anthropomorphic liver phantom in three versions. Besides these, we set up a computational phantom liver based on a physical phantom using Visual Monte Carlo. The conclusion obtained from inquiring professionals is that there is motivation for sharing and acquiring of national phantoms. The results obtained from characterization of materials used in the development of the phantoms should that such materials are suitable for the construction of such objects, observing only a change in color of acrylics irradiated with doses above 10 kGy. Through analysis of images of non anthropomorphic phantoms it is possible to study several parameters, such as sensitivity of the scintillation cameras, center of rotation, matrix size of pixels, the energy window, counting density and organs geometry. The images obtained from ANTROFÍGADO in SPECT and PET/CT systems can be useful to simulate the geometry of the healthy liver and cirrhotic liver, serving this object to the study of simulations of diagnostic analysis of location and evaluation of morphology and anomalies in the liver. Even though industrial processes for production of phantoms proposed here represent a significant increase in the final cost of these objects, it can be said that it is possible to reproduce many copies of these objects using the same methodology employed in the manufacture of the prototypes here studied. / Os objetos simuladores utilizados no Brasil são, em sua maioria, importados e de custo financeiro relativamente elevado. Embora esses objetos possam ser considerados essenciais para o uso em controle de qualidade, os custos financeiros elevados e a burocracia da importação, provavelmente, são empecilhos para a aquisição deles por parte dos serviços de medicina nuclear. O objetivo central deste trabalho foi o desenvolvimento de objetos simuladores nacionais para uso em controle de qualidade de câmaras de cintilação utilizadas em medicina nuclear e em treinamento de profissionais da área. Inicialmente, buscou-se conhecer o interesse de físicos médicos e supervisores de radioproteção em adquirir objetos simuladores e deu-se início à construção de três tipos distintos de objetos simuladores físicos: o SENCOR, para avaliação de sensibilidade e centro de rotação; o SIMUFÍGADO, que é um simulador de fígado; e ANTROFÍGADO, que é um objeto simulador antropomórfico de fígado em três versões. Além desses, elaborou-se um objeto simulador computacional de fígado baseado num simulador físico usando o Visual Monte Carlo. Pôde-se concluir, a partir da consulta aos profissionais que há motivação para o compartilhamento e aquisição de objetos simuladores nacionais. Nos resultados da caracterização dos materiais empregados para preparação dos objetos simuladores, observou-se que tais materiais são adequados para a construção dos objetos, observando-se apenas uma alteração na coloração dos acrílicos irradiados com doses acima de 10 kGy. Por meio de análises das imagens dos objetos simuladores físicos não antropomórficos é possível o estudo de parâmetros como sensibilidade das câmaras de cintilação, centro de rotação, tamanho de matriz de pixels, janela energética, densidade de contagem e geometria de órgãos. Por meio das imagens adquiridas dos ANTROFÍGADO em sistemas de SPECT e PET/CT pode-se simular a geometria do fígado sadio e com cirrose hepática, servindo tais imagens para análises diagnósticas simuladas de localização e avaliação da morfologia e das anomalias do fígado. Mesmo que processos industriais para produção dos objetos simuladores aqui propostos representem um acréscimo significativo nos custo final desses objetos, é correto afirmar que é possível reproduzir muitos exemplares desses objetos simuladores seguindo a mesma metodologia empregada na confecção desses protótipos.