This master thesis investigates the jamming of Tactical Data Links (TDLs). The goal is to make a model that is capable of giving an overview of a communication system under jamming conditions, offering the user a suggestion for the best coding scheme and modulation to use in any given situation. Investigation is primarily focused on the High Frequency (HF) band and its accompanying Beyond Line Of Sight (BLOS) capabilities. With this model, time and resources can be saved by eliminating the need to test for these parameters. After this model is made, based on information found on jamming types, the question is asked whether Additive White Gaussian Noise (AWGN) jamming can be approximated in a simpler way, specifically by looking at the results of an un-jammed system with a higher noise floor. Results show that for fast switching pulsed jammers this is possible, but there is a dependency on the modulation used. For slow switching jammers, this is not possible. The model presented can later be used as a basis to answer more operational questions. / Denna mastersarbete undersöker störningen av Tactical Data Links (TDL). Målet är att göra en modell som kan ge en överblick över ett kommunikationssystem under störningsförhållanden, och erbjuda användaren ett förslag på det bästa kodningsschemat och moduleringen att använda i en given situation. Undersökningen är främst inriktad på High Frequency (HF)-bandet och dess medföljande Beyond Line Of Sight (BLOS)-funktioner. Med denna modell kan tid och resurser sparas genom att eliminera behovet av att testa för dessa parametrar. Efter att denna modell har gjorts, baserat på information som hittats om störningstyper, ställs frågan om Additive White Gaussian Noise (AWGN) störning kan approximeras på ett enklare sätt, specifikt genom att titta på resultaten av ett system som har ett högre brusgolv. Resultaten visar att detta är möjligt för snabbväxlande pulsade störsändare, men det finns ett beroende av den modulering som används. För långsamt växlande störsändare är detta inte möjligt. Den presenterade modellen kan senare användas som underlag för att svara på mer operativa frågor / Dit afstudeerverslag doet onderzoek naar het verstoren van Tactische Data Links (TDLs). Het doel is om een model te maken dat een overzicht geeft van een communicatiesysteem dat verstoord wordt, en vervolgens de gebruiker een suggestie doet over de beste combinatie voor codering en modulatie. Er wordt vooral gekeken naar communicatie in de HF band, die wordt gekenmerkt door zijn Beyond Line Of Sight (BLOS) capaciteiten. Met dit model worden tijd en andere middelen bespaard door het overbodig maken van testen op de juiste parameters. Met dit model, waarin relevante verstoringstechnieken zijn meegenomen, wordt de vraag gesteld of het mogelijk is om AWGN-verstoring op een simpelere manier te benaderen, namelijk door het te vergelijken met een systeem met een hogere ruis vloer. Uit de resultaten blijkt dat dit wel mogelijk is voor snel schakelende gepulseerde stoorzenders, maar dat er wel rekening gehouden moet worden met het type modulatie. Voor langzaam schakelende gepulseerde stoorzenders is dit niet mogelijk. Het model wat in dit verslag gepresenteerd wordt, kan gebruikt worden als basis voor het beantwoorden van operationele vraagstukken.

In this work, the interference sensitivity of an FMCW radar has been evaluated by studying the impact on a simulated detection chain. A commercially available FMCW radar was first characterized and its properties then laid the foundation for a simulation model implemented in Matlab. Different interference methods have been studied and a selection was made based on the results of previous research. One method aims to inject a sufficiently large amount of energy in the form of pulsed noise into the receiver. The second method aims to deceive the radar into seeing targets that do not actually exist by repeating the transmitted signal and thus giving the radar a false picture of its surroundings. The results show that if it is possible to synchronize with the transmitted signal then repeater jamming can be effective in misleading the radar. In one scenario the false target even succeeded in hiding the real target by exploiting the Cell-Averaging CFAR detection algorithm. The results suggests that without some smart countermeasures the radar has no way of distinguishing a coherent repeater signal, but just how successful the repeater is in creating a deceptive environment is highly dependent on the detection algorithm used. Pulsed noise also managed to disrupt the radar and with a sufficiently high pulse repetition frequency the detector could not find any targets despite a simulated object in front of the radar. On the other hand, a rather significant effective radiated power level was required for the pulse train to achieve any meaningful effect on the radar, which may be due to an undersampled signal in the simulation. It is therefore difficult based on this work to draw any conclusions about how suitable pulsed noise is in a non-simulated interference context and what parameter values to use.

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Thesis purpose: The thesis purpose is to examine the interrelationship of consumer and brand relation. The main objective is to research how consumers’ perception of brand personalization before and after seeing Adbusters subvertisement ads influences their relation to brands. Methodology: The thesis has deductive quantitative research approach, since it starts from theory to gain more understanding of the research area. The data is collected through an online questionnaire. Theoretical perspective: This study is based upon the general brand and branding definitions, with focus on brand personality, consumer perception and findings within the study of Adbusters. Empirical data: The study is investigated quantitatively. An online questionnaire was used to gather the empirical data. Conclusion: This study provides a broad overview about consumer perception of brand personalized commercial ads and what is their relation to brands after seeing Adbusters subvertisement ads. The research contributes to brand personalization theory and Adbusters studies and demonstrates that Adbusters influence on brand personalization depends on how strong the consumer-brand relationship is. However, it is also shown that consumers are inconsistent in their perception of brand personas and that relation to brands is highly brand-specific.

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Many different physical systems, such as granular materials, colloids, foams and emulsions exhibit a jamming transition where the system changes from a liquid-like flowing state to a solid jammed state as the packing fraction increases. These systems are often modeled using soft-core particles with repulsive contact forces. In this thesis we explore several different dynamical models for these kinds of systems, and see how they affect the behavior around the jamming transition. We investigate the effect of different types of dissipative forces on the rheology, and study how different methods of preparing a particle configuration affect their probability to jam when quenched. We study the rheology of sheared systems close to the jamming transition. It has been proposed that the athermal jamming transition is controlled by a critical point, point J, with certain scaling properties. We investigate this using multivariable scaling analysis based on renormalization group theory to explore the scaling properties of the transition and determine the position of point J and some of the critical exponents.

The convenience of IEEE 802.11-based wireless access networks has led to widespread deployment. However, these applications are predicated on the assumption of availability and confidentiality. Error-prone wireless networks afford an attacker considerable flexibility to exploit the vulnerabilities of 802.11-based mechanism. Two of most famous misbehaviors are selfish and malicious attacks. In this thesis we investigate two attacks: Spurious CTS attack (SCTS) and Jamming ACK attack (JACK). In the SCTS, malicious nodes may send periodic Spurious CTS packets to force other nodes to update their NAV values and prevent them from using the channel. In the JACK, an attacker ruins legitimate ACK packets for the intention of disrupting the traffic flow and draining the battery energy of victim nodes quickly. Correspondingly, we propose solutions: termed Carrier Sensing based Discarding (CSD), and Extended Network Allocation Vector (ENAV) scheme. We further demonstrate the performance of our proposed schemes through analysis and NS2 simulations.

Les mouvements cellulaires collectifs jouent un rôle fondamental dans de nombreux phénomènes biologiques (développement, régénération, cancer, etc.). Pour autant, les mécanismes régissant ces mouvements sont toujours mal connus. Nous nous proposons dans cette thèse d'étudier deux situations expérimentales mettant en jeu ces mouvements dans des monocouches cellulaires.Nous nous intéressons en premier lieu à des cellules HBEC, épithéliales mais peu cohésives. On calcule par PIV (vélocimétrie par images de particules) le champ de vitesse dans des populations de cellules déposées de manière homogène sur le substrat. On observe un ralentissement des mouvements et une progression non monotone de leur corrélation spatiale en fonction du temps. La combinaison de nos expériences, d'un modèle analytique et de simulations nous permet de conclure que cette évolution est la signature d'une transition de jamming contrôlée par la vitesse et que le ralentissement est dû à une maturation des jonctions cellule-cellule et des adhésions cellules-substrat.Nous étudions ensuite la compétition pour l'espace entre deux lignées HEK-HT, l'une normale et l'autre transformée par une mutation oncogénique RasV12. On dépose face à face les deux populations, porteuses d'un fluorophore différent, séparées par une bande de substrat libre pour les faire migrer l'une vers l'autre. On combine l’analyse des images de fluorescence aux techniques de PIV pour étudier la dynamique des deux fronts de population. Après contact et malgré un certain mélange des deux types, les monocouches forment une interface relativement bien définie qui se déplace dans le sens d'avancée du type transformé. / Collective cellular motion plays a fundamental role in several biological phenomena: development, regeneration, cancer, etc. However, the mechanisms behind this motion are still poorly understood. In this thesis, we study two experimental situations involving collective motion in cellular monolayers.We first look at HBEC cells, which are epithelial but weakly cohesive. Using particle image velocimetry (PIV), we monitor the velocity field in populations of cells homogeneously seeded on the susbtrate. We observe a slowdown in the cellular motion as its spatial correlation non-monotonically changes with time. Combining our experiments with an analytical model and simulations allows us to conclude that the system undergoes a jamming transition with speed as the main control parameter. We also show that the observed slowdown is a consequence of the maturation of cell-cell junctions and cell-substrate adhesions.We then study the competition for space between two HEK-HT cell lines, one being normal and the other being transformed by an oncogenic RasV12 mutation. The two fluorescently-labeled populations are set to migrate antagonistically towards an in-between stripe of free substrate. Through analysis of the fluorescence images and PIV methods, we study the dynamics of both population fronts. After contact, even though the two types mix to a certain extent, we observe a relatively well-defined interface, which moves towards the normal population.

<p>Flow in a hopper is both a fertile testing ground for understanding fundamental granular flow rheology and industrially highly relevant. Despite increasing research efforts in this area, a comprehensive physical theory is still lacking for both jamming and flow of granular materials in a hopper. In this work, I have designed a two dimensional (2D) hopper experiment using photoelastic particles ( particles' shape: disk or ellipse ), with the goal to build a bridge between macroscopic phenomenon of hopper flow and microscopic particle-scale dynamics. Through synchronized data of particle tracking and stress distributions in particles, I have shown differences between my data of the time-averaged velocity/stress profile of 2D hopper flow with previous theoretical predictions. I have also demonstrated the importance of a mechanical stable arch near the opening on controlling hopper flow rheology and suggested a heuristic phase diagram for the hopper flow/jamming transition. Another part of this thesis work is focused on studying the impact of particle shape of particles on hopper flow. By comparing particle-tracking and photoelastic data for ellipses and disks at the appropriate length scale, I have demonstrated an important role for the rotational freedom of elliptical particles in controlling flow rheology through particle tracking and stress analysis. This work has been supported by International Fine Particle Research Institute (IFPRI) .</p> / Dissertation