ABSTRACT IMPLEMENTATION OF NORTHFINDING TECHNIQUES Oguz, Pinar MS, Department of Electrical and Electronics Engineering Supervisor: Assoc. Prof. Dr. T.Engin Tuncer June 2006, 131 pages The fundamental problem of navigation is to find the initial north angle of the body with respect to the reference frame. Determination of the north angle of the body frame is required in spacecraft, aircraft, sea-craft, land-craft and missile control and guidance. This thesis discusses implementation and comparison of four northfinding techniques. These are GPS (Global Positioning System) based with integer search, GPS based with Kalman filter, accelerometer based and IMU (Inertial Measurement Unit) based techniques. The north angle is determined by the processing of difference measurements of the GPS carrier phase between two antennas at GPS based northfinding techniques. Carrier phase ambiguity resolution is the main problem in GPS based techniques. Since, GPS receiver measures only the fractional part of the carrier phase. Therefore, integer part remains unknown. Two distinct ideas are applied to solve carrier phase ambiguities in two techniques. One of them is integer search on single phase difference. Suitable integer sets are checked on the cost function which is constructed from the single phase difference between two antennas. The other technique uses integer estimator and attitude estimator with Kalman filter rely on double difference phase measurements which are obtained from carrier phase differences of two antennas and two satellites at one instant. To test the GPS based techniques, a realistic GPS emulator is implemented. GPS emulator provides typical GPS raw navigation data including satellite positions, pseudoranges and carrier phases. Accelerometer based northfinding technique is composed of a vertically placed linear accelerometer on a rotating platform. The north angle is found by Coriolis acceleration due to Earth and platform rotation. Implementation problems of this technique in practice are discussed. IMU based northfinding technique has inertial sensor components such as gyroscopes and accelerometers to sense the Earth rotation rate and gravitational force respectively. The north angle is found by the processing of these inertial sensors output. Real set-up is established to test the IMU based technique.

Concerns about climate change brought about by the increasing usage of fossil fuels has made it imperative to develop sustainable energy usage based on renewable sources. Micro-hydel plants are an important source of renewable energy that can be exploited to supply requirements of local loads in remote locations while operating as an isolated source, or the larger network when operating in grid connected mode. The focus of this research is to develop an alternative topology to the one currently in use in micro-hydel power plants. While existing plants are based on a ballast-controlled, fixed-speed, operator-supervised model, the proposed work introduces a ballast-free, variable-speed generator capable of unsupervised operation. Conventional micro-hydel generators use o-the-shelf machines with the purported aim of reducing costs. They run at a fixed speed, maintaining constant electrical load by switch-ing a plant-situated ballast load to compensate for consumer load changes. Although the intention is to have a simplified control scheme and reduced costs, the conventional plants end up being expensive since the balance-of-system costs are increased. The plant re-quires supervision by a trained operator and frequent maintenance, failing which the reliability suers. The cost and maintenance reduction possible is analysed by comparing the proposed topology with a typical well designed conventional micro-hydel plant. The proposed topology takes the characteristics of the turbine into account, and by running at variable speed, ensures that only as much power is generated as required by the consumer load. This eliminates the ballast load and associated problems present in conventional plants. The generator can be connected to the grid, if present, enabling the available power to be fully utilized. The behavior of a hydraulic turbine operating at a fixed head and discharge rate with no flow control is analyzed. Based on the turbine characteristics, a generator topology is developed, which operates in a speed range dictated by the characteristics of the turbine. Continual supervision is unnecessary since the operation of the generator is within safe limits at all times. A simple emulator that can mimic the steady state and dynamic behaviour of the turbine is developed to test the proposed generator. The two-machine wound rotor generator proposed has an auxiliary exciter similar to a conventional brushless alternator with the additional provision for bidirectional power transfer. The shaft mounted rotor side electronics facilitate brushless operation, and to-gether with the stator side controllers form an embedded system that does away with having to tune the plant in-situ. The control scheme is evaluated for expected perfor-mance in dierent operating modes. The thesis also discusses an optimization of the synchronous speed of the generator with respect to the turbine characteristics. This minimizes the bidirectional slip power transfer requirements of the rotor side converters and leads to the lowest rating for the auxiliary machine. The proposed generator can then operate like a conventional synchronous gen-erator in the grid connected mode with a simplified control scheme.

Quality of Service is major factor for a successful business in modern and future network services. A minimum level of services is assured indulging quality of Experience for modern real time communication introducing user satisfaction with perceived service quality. Traffic engineering can be applied to provide better services to maintain or enhance user satisfaction through reactive and preventive traffic control mechanisms. Preventive traffic control can be more effective to manage the network resources through admission control, scheduling, policing and traffic shaping mechanisms maintaining a minimum level before it get worse and affect user perception. Accuracy, dynamicity, uniformity and reproducibility are objectives of vast research in network traffic. Real time tests, simulation and network emulation are applied to test uniformity, accuracy, reproducibility and dynamicity. Network Emulation is performed over experimental network to test real time application, protocol and traffic parameters. DummyNet is a network emulator and traffic shaper which allows nondeterministic placement of packet losses, delays and bandwidth changes. KauNet shaper is a network emulator which creates traffic patterns and applies these patterns for exact deterministic placement of bit-errors, packet losses, delay changes and bandwidth changes. An evaluation of KauNet with different patterns for packet losses, delay changes and bandwidth changes on emulated environment is part of this work. The main motivation for this work is to check the possibility to delay and drop the packets of a transfer/session in the same way as it has happened before (during the observation period). This goal is achieved to some extent using KauNet but some issues with pattern repetitions are still needed to be solved to get better results. The idea of history and trace-based traffic shaping using KauNet is given to make this possibility a reality.

The goal of this thesis is to create a virtual machine that emulates a running programs written in Java programing language, which would be suitable for malware analysis and detection. The emulator is able to detect arguments of exploitable methods from Java standard classes, the order of calling these exploitable methods and also execution the test application. Overall functionality was tested on appropriate examples in which held its own measurements. At the end of the paper we describe testing of the emulator, which also contains tables and graphs for better results visualization.

The work deals with verification of the metadata of audio recordings in an environment of mobile phones running Android. The text work is divided into three main parts. The first part is focused more on theoretical basis, where the main emphasis on the description of Android, application structure, description of the audio MP3 file and theoretical basis of Fourier transform in signal processing. The second part is devoted to solution design, analysis and implementation. The third part deals with testing.

Ces travaux portent sur l'étude et le développement d'un système de caractérisation de radioaltimètres. La propagation Air-Sol-Air, contexte particulier du canal de propagation aéronautique adaptée aux radioaltimètres, est étudiée et modélisée. Une approche hybride basée sur le lancer de rayon et les fonctions de distribution de la réflectance bidirectionnelle est proposée pour le développement d'un simulateur de canal de propagation dédié aux radioaltimètres. Les modèles issus de cet outil sont validés par confrontation à des essais en vol et une méthode de conditionnement des résultats est proposée pour les rendre utilisables dans un accumulateur de canaux de propagation temps réel. L'architecture matérielle et logicielle de celui-ci est détaillée dans ce manuscrit et son fonctionnement est validé par la mesure. / This thesis presents the study and the development of a radar-altimeter characterization tool. The Air-Ground-Air propagation channel is a specific context of the aeronautical channel applied to the radar-altimeters. A new hybrid method designed to the development of a channel simulator is described. This one is based upon ray tracing and bidirectionnal reflectance distribution functions and permits to obtain channel models validated by comparison with on flight measurements. A pre-conditioning method is also explained to make the channel models ready to be used in a real time channel emulator. The hardware and software architecture of this channel emulator is detailed in this book and its behavior is validated with laboratory measurements.

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<p>У тези je предложен поступак развоја управљачких склопова енергетске<br />електронике заснован на технологији Hardware In the Loop. Подробно је<br />описан предложени емулатор са нагласком на специфичном<br />моделовању погодном за извршење у стварном времену што је<br />предуслов веродостојности. Сама веродостојност је проверена<br />поређењем резултата са симулацијом, као и са измереним резултатима<br />у неколико стварних погона. Затим је поступак развоја управљачких<br />склопова подробно објашњен на примеру развоја и испитивања једног<br />новог контролног алгоритма за повезивање синхроног генератора на<br />електричну мрежу.</p> / <p>U tezi je predložen postupak razvoja upravljačkih sklopova energetske<br />elektronike zasnovan na tehnologiji Hardware In the Loop. Podrobno je<br />opisan predloženi emulator sa naglaskom na specifičnom<br />modelovanju pogodnom za izvršenje u stvarnom vremenu što je<br />preduslov verodostojnosti. Sama verodostojnost je proverena<br />poređenjem rezultata sa simulacijom, kao i sa izmerenim rezultatima<br />u nekoliko stvarnih pogona. Zatim je postupak razvoja upravljačkih<br />sklopova podrobno objašnjen na primeru razvoja i ispitivanja jednog<br />novog kontrolnog algoritma za povezivanje sinhronog generatora na<br />električnu mrežu.</p> / <p>This paper proposes development of Power Electronics controllers based on<br />the Hardware In the Loop technology. Proposed emulator is describied in<br />detail where emphasis was set on specific methods of modeling which is<br />suitable for real time emulations in order to obtain emulation faithfulness.<br />Fidelity itself was checked through comparison with off-line simulations and<br />results of real drives. Procedure of controllers development was presented<br />through development and testing of one new control algorithm for connection<br />of the permanent magnet synchronous generator to the electrical grid.</p>

Ce travail s’intéresse à l’étude d’un système de pompage turbinage à vitesse variable avec une machine asynchrone doublement alimentée face aux perturbations de réseau électrique. L’objectif est d’assurer la continuité de service de cet élément stabilisateur de réseau électrique de sorte qu’il reste connecté au réseau même en cas de perturbations. Le contrôle du système dans les différentes phases de fonctionnement en mode sain a été tout d’abord développé ainsi qu'une étude de stabilité de système utilisant l’analyse modale. Les différents outils nécessaires pour cette analyse ont été tout d’abord mis en oeuvre. Ensuite, les limites de stabilité du système ont été étudiées tenant compte de la variation de longueur de ligne. Le comportement du système en présence des défauts a été par la suite étudié. Les défauts de réseau considérés sont les défauts symétriques et les défauts asymétriques. Une solution basée sur la modification de la stratégie de contrôle a été adoptée pour le cas des défauts symétriques et une solution basée sur l’ajout d’éléments au circuit de puissance a été adoptée pour les cas des défauts asymétriques. Un dispositif expérimental de 4kW a été mis en oeuvre pour la validation des développements menés dans le cadre de cette thèse. / This work focuses on the study of a variable speed pumped storage system based on a doubly fed induction machine in case of grid disturbances. Thus the main objective is to improve the fault ride through capabilities of this grid stabilizer and to guarantee its connection with the grid even under disturbances. The system control in the different operating phases in healthy conditions is developed and then a system stability study is conducted using the eigenvalue analysis. The system stability limits have been investigated taking into account the variation of grid line length so the grid impedance variation. Then the system behavior under disturbances is analyzed. Theconsidered grid faults are symmetric and asymmetric faults. The investigated fault ride through capabilities of the pumped storage system consist of two solutions, one based on the modification of the control strategy was adopted for the symmetric faults and one based on hardware modification has been adopted for the asymmetric ones. A 4kW laboratory set-up has been developed for experimental validation.

Abstract The worldwide success of wireless communications was originally fueled by the possibility to replace existing cables with wireless solutions. This phenomenon imposed the development of security engineering as a multidisciplinary field. Although wireless solutions can reduce installation costs and allow introducing new services, the end–users expect it to have the same level of security as they would normally have with wired solutions. Secure communications is an important part of the overall security of industrial wireless communications systems (IWCS). The aim of this thesis is to develop new security engineering methodologies for IWCS. The author develops countermeasures against confidentiality and integrity attacks and carries out a security analysis covering the protocol, electromagnetic and physical layer. In the first part of the thesis, Host Identity Protocol (HIP) is utilized to secure communication in an intra–vehicular network. Simulations and measurement campaigns are also conducted to evaluate the impact of the overhead on security in a tunnel, considering line–of–sight (LOS) and non–LOS (NLOS) scenarios. Electromagnetic analysis (EMA) is an important step in the development of safety–related systems. Today, the increasing usage of smaller integrated circuit also increases the susceptibility to electromagnetic (EM) interference. From near–field (NF) to far–field (FF) transformation, a method for the evaluation of the emissions leakage is investigated. The virtual EM (VEM) interface of the device–under–test (DUT) is studied, and it is described how an adversary can exploit it for denial of service (DoS) attacks. An effective jamming attack model is studied, and the theoretical calculations are validated with experiment–based results. Finally, focusing attention on physical layer security, two algorithms are developed. Active radio frequency fingerprinting (RFF) implements the exchange of a public key during the setup of secure communication. Afterwards, utilizing a jamming receiver in conjunction with the spread spectrum (SS) watermarking technique, the watermark–based blind physical layer security (WBPLSec) protocol is presented. The analysis and results indicate how the WBPLSec seems to be a valuable technique for deploying physical layer security by creating a secure region around the receiver. / Tiivistelmä Langattoman tietoliikenteen maailmanlaajuista suosiota kiihdytti alun perin mahdollisuus korvata tietoliikennejärjestelmissä käytetyt kaapelit langattomilla ratkaisuilla. Ilmiö lisäsi myös tarvetta kehittää alan turvatekniikkaa monialaisen tutkimuksen pohjalta. Vaikka langattomat ratkaisut merkitsevät pienempiä asennuskustannuksia ja tarjoavat mahdollisuuksia luoda uudenlaisia palveluja, järjestelmien loppukäyttäjät edellyttävät kuitenkin niiden turvallisuuden olevan vastaavalla tasolla kuin langallisissa verkoissa. Myös teollisuuden langattomien tietoliikennejärjestelmen turvallisuus riippuu pitkälti viestintäkanavien turvallisuudesta. Väitöksen tavoitteena on kehittää uusia menetelmiä, joilla teollisuuden langattomat tietoliikennejärjestelmät voitaisiin turvata. Väitöksessä kehitetään toimenpiteitä tietoliikennejärjestelmien luottamuksellisuuteen ja koskemattomuuteen kohdistuvia hyökkäyksiä vastaan ja toteutetaan turvallisuusarviointi, joka kattaa järjestelmän protokollakerroksen sekä sähkömagneettisen ja fyysisen kerroksen. Väitöksen ensimmäisessä osassa hyödynnetään HIP–protokollaa (Host Identity Protocol) liikennevälineen sisäisen tietoliikennejärjestelmän turvallisuuden varmistamisessa. Lisäksi siinä kuvataan simulaatiot ja mittaushankkeet, joiden tavoitteena on arvioida käytetyn protokollan turvallisuusvaikutuksia esteettömän (line–of–sight, LOS) ja esteellisen (non–line–of–sight, NLOS) näköyhteyden tapauksissa. Sähkömagneettinen analyysi on tärkeä vaihe turvajärjestelmien kehitysprosessissa. Järjestelmissä käytetään yhä enemmän pieniä integroituja piirejä, mikä voi myös altistaa ne sähkömagneettisille (electromagnetic, EM) häiriöille. Väitöksessä tutkitaan lähikenttä–kaukokenttä -muunnokseen perustuvan arviointimenetelmän avulla sähkömagneettisen vuotosäteilyn tasoa. Lisäksi perehdytään testattavan laitteen (device under test, DUT) virtuaaliseen EM–liitäntään ja kuvataan, miten vastaavaa liitäntää voidaan hyödyntää palvelunestohyökkäyksissä. Väitöksessä tutkitaan myös tehokasta häirintämallia ja validoidaan teoreettisten laskelmien tulokset kokeellisesti. Lopuksi väitöksessä keskitytään tietoliikennejärjestelmän fyysisen kerroksen turvallisuuteen ja kehitetään kaksi algoritmia. Aktiivisen radiotaajuisen tunnistusmenetelmän avulla voidaan vaihtaa julkisia avaimia turvallista tietoliikenneyhteyttä muodostettaessa. Lisäksi esitellään vesileimausmenetelmään perustuva fyysisen kerroksen salausmenetelmä, WBPLSec. WBPLSec luo vastaanottimen ympärille suoja–alueen, minkä ansiosta se vaikuttaa analyysin ja tutkimustulosten perusteella olevan tehokas menetelmä toteuttaa fyysisen kerroksen suojaus.