Approved for public release, distribution is unlimited / The United States Navy requires radical and innovative ways to model and design multifunction phased array radars. This thesis puts forth the concept that Genetic Algorithms, computer simulations that mirror the natural selection process to develop creative solutions to complex problems, would be extremely well suited in this application. The capability of a Genetic Algorithm to predict adequately the behavior of an array antenna with randomly located elements was verified with expected results through the design, construction, development and evaluation of a test-bed array. The test-bed array was constructed of commercially available components, including a unique and innovative application of a quadrature modulator microchip used in commercial communications applications. Corroboration of predicted beam patterns from both Genetic Algorithm and Method of Moments calculations was achieved in anechoic chamber measurements conducted with the test-bed array. Both H-plane and E-plane data runs were made with several phase steered beams. In all cases the measured data agreed with that predicted from both modeling programs. Although time limited experiments to beam forming and steering with phase shifting, the test-bed array is fully capable of beam forming and steering though both phase shifting and amplitude tapering. / Outstanding Thesis / Lieutenant Commander, United States Navy

[pt] Os Ensaios Não-Destrutivos são técnicas utilizadas na inspeção de materiais e equipamentos sem dano a integridade física, podendo ser executados nas etapas de pós-fabricação, montagem, operação e manutenção. São utilizados pela indústria como ferramenta de controle e garantia da qualidade de materiais, produtos e processos. Esta pesquisa teve como objetivo identificar trincas e estimar o seu comprimento em corpos de prova de aço DIN 42CrMo4, adotando diferentes técnicas de END. Os corpos de prova foram de um eixo virabrequim de um motor Diesel, utilizado como unidades geradora em usinas termoelétricas, que falhou por fadiga de baixo ciclo. Os corpos de prova foram projetados de acordo com as normas ASTM E1820, ASTM E1290 e ISO 15653, bem como adotando sugestões de inspetores de ultrassom quanto a uma geometria que otimizasse a eficiência das medições. Subsequente ao trincamento dos corpos de prova em fadiga, os mesmos foram inspecionados com o emprego das técnicas de Radiografia Digital (RD), Ultrassom Phased Array (UT-PA), métodos Pulso-Eco (PE) e Time os Flight Diffraction (TfOD), e Tomografia Computadorizada (TC). Em sequência, os corpos de prova foram fraturados com o uso de uma carga em flexão e nitrogênio liquido, o que permitiu a medição real dos comprimentos das trincas. As técnicas de UTPA, RD e TC indicaram tamanhos de trincas próximos entre si. Nos métodos de PE e ToFD, de UT-PA, se observou que a indicação das trincas sofre influência da distancia entre o cabeçote do equipamento e a posição da trinca. Em trincas menores, essa influência é mais acentuada, levando a uma medição errônea do comprimento da trinca. A técnica de RD apresentou um bom resultado da medida lateral da trinca, porem foi necessário um processamento digital da imagem para obtenção de melhores resultados, explicado devido a sensibilidade do ensaio à geometria do corpo de prova e da densidade do material utilizado. Já a TC apresentou imagens melhores e medidas de trinca similares se comparada com a RD, o que pode influenciar em outros tipos/dimensões de defeitos. Em compensação, sofre mais influencia do volume de material presente no entorno do defeito, o que impossibilitou a detecção de defeitos em algumas amostras. / [en] Non-Destructive Testing (NDT) are techniques applied to materials and equipment inspection without integrity degradation and can be performed in the post-manufacture, assembly, operation and maintenance stages. Those techniques are used by the industry to control a guarantee the quality of materials, products and processes. The aim of this research was to identify cracks and estimate their length on DIN 42CrMo4 steel specimens adopting different NDT techniques. The material to the test specimen was taken from a crankshaft of a Diesel engine, utilized as generating units in thermoelectric power plant, which has failed due to low cycle fatigue. The test specimen were designed according to ASTM E1820, ASTM E1290 and ISO 15653 standards, as well as suggestions made by NDT inspectors for a geometry that optimized the efficiency of the measurement. Subsequent to the fatigue induced crack on the specimens, they were inspected using, Digital Radiography (RD), Phased Array Ultrasound (UT-PA), Pulse-Echo (PE) and Time of Flight Diffraction (ToFD) methods, and Digital Tomography (TC). The specimens were then fractured with a bending load and liquid nitrogen, which allowed the measurement of the real crack length. UT-PA, PE and ToFD, and RD techniques showed a closer estimate crack size among then. It was observed that both UT-PA methods, PE and ToFD, presented an influence of the distance between the equipment head and the crack position, on the crack measurement. This was more pronounced in smaller cracks, leading to an erroneous measurement of the crack length. The RD technique presented a good a good result of lateral crack length, but a good digital image processing was necessary to obtain these results, explained by the sensitivity of the test to the geometry to the geometry of the specimen and to the material density. TC presented better imaging and similar lateral crack lengths when compared to RD, which could influence the detection of other types/dimensions of defects. In contrast, it is more influenced by the volume of material around the object, which made it impossible to detect defects in some samples.

No description available.

Recent developments in the area of microfabrication technologies, has enabled the fabrication of many radio frequency/microwave components with better performance and lower cost than possible with semiconductor based fabrication technology. Many of these microfabricated RF components such as switches and phase shifters, popularly known as RF MEMS, are aimed at reducing the insertion loss and improving other performance parameters such as linearity. For these devices size miniaturization is not necessarily important, as in practical subsystems, these components are integrated with RF front-ends on a laminate. This thesis deals with concepts of a low cost passive phase shifter fabricated in-situ on a microwave laminate. The operation of this Mesoscale Electrostatically actuated Phase shifter on microwave Laminate (MEPL) is similar to that of a micromachined distributed MEMS transmission line (DMTL) phase shifter. In spite of advantages of low losses, wide bandwidth, low DC power consumption and high linearity over semiconductor/MMIC technology, microfabricated phase shifters are often not used in field because of issues related to fabrication reliability, packaging and integration. On the other hand, the proposed MEPL will have all the advantages of conventional MEMS phase shifters with additional benefit of lower cost. Furthermore, these are integrable to form a monolithic phased array. A MEPL phase shifter of 50-bridges periodically distributed on the co-planar waveguide (CPW) transmission line is demonstrated in this thesis. MEMS air bridges are electrostatically actuated to vary the capacitance of the transmission line, which changes the phase velocity of the propagation RF signal, consequently phase at the output port. The realized MEPL is characterized for electromagnetic as well as electromechanical performance. The electromechanical characterization of this device is performed using a Laser Doppler Vibrometer (LDV). The measured data showed good agreement with the analytical data.. Major application of a phase shifter is in a phased array antenna system. MEPL is particularly suited for a monolithic phase array antenna. The proposed monolithic phased array antenna system fabrication approach utilizes extremely simple and economical modern printed circuit board technology to pattern the conventional microwave laminate and copper foil. A complete monolithic phased array antenna system is fabricated on a microwave laminate using an embedded phase shifter operating with electrostatic principles. Other components such as DC block and bias tee are integrated into the CPW-microstrip transitions to optimize the space and performance. Integrated phased array antenna is fabricated and tested to demonstrate the beam steering capability. Measured S11 is better than -15dB at the operating frequency of 9.8GHz. The beam steering capability is shown as proof of concept by showing the beam scan angle of 10deg with bias voltage of 125V. The mesoscale phase shifter demonstrated in this thesis has several advantages compared to micromachined phase shifters. The proposed fabrication approach does not use metal deposition/patterning process, which removes the need of high cost clean room and sophisticated films deposition equipments. Secondly, as there are no thin films used, stiction is not expected on phase shifters fabricated with this approach. Since this approach uses thicker metal films, the power handling capability is expected to be significantly higher than micromachined phase shifters. Since conventional phased array antenna system components are fabricated on a microwave laminate, micro machined phase shifters realized on semiconductor substrates are required to be packaged separately before integrating with such phased array circuits. Packaging of the micro-machined RF-MEMS/MEMS devices is still a major issue and contributes to a substantial part of the total cost. Unlike micromachined phase shifters which are required to be packaged and then embedded in phased array applications, device presented in this thesis is packaged in-situ. Compared to similar monolithic phased array antenna reported on silicon substrate which are limited by wafer size, these arrays can be easily extended for larger arrays on microwave laminate as these are available in large size. To summarize, the proposed fabrication approach for phase shifters overcomes many limitations of micromachined components for microwave applications while retaining most of their advantages compared to other existing approaches based on ferrites or semiconductor technologies.

Avec l'augmentation de l'utilisation des smartphones, des objets connectés et des véhicules automatiques, le domaine des systèmes embarqués est devenu omniprésent dans notre environnement. Ces systèmes sont souvent contraints en terme de consommation et de taille. L'utilisation des processeurs many-cores dans des systèmes embarqués permet une conception rapide tout en respectant des contraintes temps-réels et en conservant une consommation énergétique basse.Exécuter une application sur un processeur many-core requiert un dispatching des tâches appelé problème de mapping et est connu comme étant NP-complet.Les contributions de cette thèse sont divisées en trois parties :Tout d'abord, nous étendons d'importantes propriétés dataflow au modèle Phased Computation Graph.Ensuite, nous présentons un générateur de graphe dataflow capable de générer des Synchonous Dataflow Graphs, Cyclo-Static Dataflow Graphs et Phased Computation Graphs vivant avec plus de 10000 tâches en moins de 30 secondes. Le générateur est comparé à SDF3 et PREESM.Enfin, la contribution majeure de cette thèse propose une nouvelle méthode d'évaluation d'un mapping en utilisant les modèles Synchonous Dataflow Graphe et Cyclo-Static Dataflow Graphe. La méthode évalue efficacement la mémoire consommée par les communications d'un dataflow mappé sur une architecture à mémoire distribuée. L'évaluation est déclinée en deux versions, la première garantit la vivacité alors que la seconde ajoute une contrainte de débit. La méthode d'évaluation est expérimentée avec des dataflow générés par Turbine et avec des applications réelles. / With the increasing use of smart-phones, connected objects or automated vehicles, embedded systems have become ubiquitous in our living environment. These systems are often highly constrained in terms of power consumption and size. They are more and more implemented with many-core processor array that allow, rapid design to meet stringent real-time constraints while operating at relatively low frequency, with reduced power consumption.Running an application on a processor array requires dispatching its tasks on the processors in order to meet capacity and performance constraints. This mapping problem is known to be NP-complete.The contributions of this thesis are threefold:First we extend important notions from the Cyclo-Static Dataflow Graph to the Phased Computation Graph model and two equivalent sufficient conditions of liveness.Second, we present a random dataflow graph generator able to generate Synchonous Dataflow Graphs, Cyclo-Static Dataflow Graphs and Phased Computation Graphs. The Generator, is able to generate live dataflow of up to 10,000 tasks in less than 30 seconds. It is compared with SDF3 and PREESM.Third and most important, we propose a new method of evaluation of a mapping using the Synchonous Dataflow Graph and the Cyclo-Static Dataflow Graph models. The method evaluates efficiently the memory footprint of the communications of a dataflow graph mapped on a distributed architecture. The evaluation is declined in two versions, the first guarantees a live mapping while the second accounts for a constraint on throughput.The evaluation method is experimented on dataflow graphs from Turbine and on real-life applications.

Multi-standard RF front-end is a critical part of legacy and future emerging mobile architectures, where the size, the efficiency, and the integration of the elements in the RF front-end will affect the network key performance indicators (KPIs). This chapter discusses power amplifier design for both handset and base station applications for 5G and beyond. Also, this chapter deals with filter-antenna design for 5G applications that include a synthesis-based approach, differentially driven reconfigurable planar filter-antenna, and an insensitive phased array antenna with air-filled slot-loop resonators.

International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / This paper describes a system of Total Border Surveillance, which is cost effective, closes existing gaps and is less manpower intensive than the current techniques. The system utilizes a fleet of commercially available aircraft converted to unmanned capability, existing GPS and surveillance systems and autonomous ground stations to provide the desired coverage.

There are many methods for modelling the reliability of systems based on component failure data. This task becomes more complex as systems increase in size, or undertake missions that comprise multiple discrete modes of operation, or phases. Existing techniques require certain levels of expertise in the model generation and calculation processes, meaning that risk and reliability assessments of systems can often be expensive and time-consuming. This is exacerbated as system complexity increases. This thesis presents a novel method which generates reliability models for phasedmission systems, based on Petri nets, from simple input files. The process has been automated with a piece of software designed for engineers with little or no experience in the field of risk and reliability. The software can generate models for both repairable and non-repairable systems, allowing redundant components and maintenance cycles to be included in the model. Further, the software includes a simulator for the generated models. This allows a user with simple input files to perform automatic model generation and simulation with a single piece of software, yielding detailed failure data on components, phases, missions and the overall system. A system can also be simulated across multiple consecutive missions. To assess performance, the software is compared with an analytical approach and found to match within 5% in both the repairable and non-repairable cases. The software documented in this thesis could serve as an aid to engineers designing new systems to validate the reliability of the system. This would not require specialist consultants or additional software, ensuring that the analysis provides results in a timely and cost-effective manner.

The thermodynamic equation of seawater - 2010 (TEOS-10) is hampered by the inability to measure absolute salinity or density in situ. No new advances for in situ salinity or density measurement have taken place since the adoption of the practical salinity scale in 1978. In this thesis three possible technologies for in situ measurements are developed and assessed: phased conductivity, an in situ density sensor and sound speed sensors. Of these, only sound speed sensors showed the potential for an in situ TEOS-10 measurement solution. To be implemented, sensor response times need to be matched and the sound speed sensor accuracy must be improved. Sound speed sensor accuracy is primarily limited by the calibration reference, pure water. Test results indicate the TEOS-10 sound speed coefficients may also need to be improved. A calibration system to improve sound speed sensor accuracy and verify the TEOS-10 coefficients is discussed. / Graduate / 0415 / 0986 / TDakin@UVic.ca

Dès lors que des éléments rayonnants sont placés à proximité les uns des autres, comme c'est le cas au sein des antennes réseaux à balayage électronique, des interactions électromagnétiques parasites se créent entre eux. Ces couplages se manifestent par une perturbation des répartitions de courants des sources du réseau. Leur impact dépend fortement de l'angle de dépointage du réseau mais est généralement néfaste, car ils modifient les caractéristiques du rayonnement des sources. Les différents objectifs de compacité et les spécifications de performances radioélectriques visés pour les radars aéroportées peuvent conduire à des structures qui supportent et favorisent ces phénomènes de couplages parasites, sous la forme d’ondes d’espace et de surface. Ces derniers peuvent aller jusqu'à entrainer l'impossibilité pour l'antenne de rayonner dans certaines directions et à certaines fréquences d’utilisation : on parle de directions aveugles. Ce phénomène limite de manière considérable le volume de dépointage opérationnel d'un système radar. La maîtrise du couplage entre les éléments rayonnants est donc l'une des problématiques essentielles du développement et du dimensionnement d'une antenne réseau. La recherche qui traite de ce sujet n'en est plus à ses débuts (les premiers radars à balayage électronique sont exploités depuis les années 50) mais reste toujours en attente de solutions innovantes permettant de mieux comprendre et maîtriser ces phénomènes. Dans cette thèse, plusieurs méthodes permettant de minimiser les effets du couplage dans les réseaux à balayage électroniques ont été investiguées. Les travaux s'orientent notamment autour du défi de réduire les conséquences des directions aveugles sans modifier la maille initiale du réseau d'antenne (contrainte iso-maille). / When radiating elements are located close to one another, as it is the case in electronically phased array antennas, parasitic electromagnetic interferences occur between them. The impact of these coupling mechanisms depends to a large extent on the scanning angle of the array, but is usually harmful, since it alters the radiating properties and the active input impedance of the sources. The compactness objectives and radioelectric performances required for airborne radars can lead to structures that support and foster these parasitic couplings, in the form of surface or space waves. In some cases, mutual coupling can even result in the impossibility for the array to radiate in certain directions and at certain frequencies. This phenomenon, referred to as scan blindness, significantly reduces the operating scan volume of a radar system. In that respect, the control of coupling mechanisms between radiating elements is a major issue when developing an array antenna and although the research that deals with this subject is no longer in its infancy, it is always pending for new and innovating solutions to master these phenomena. In this thesis, different solutions enabling to minimize the effect of couplings in phased arrays are investigated. The presented research revolves around the challenge of limiting scan blindness consequences without modifying the initial mesh of the array antenna.