This thesis reports on the investigations of resistive-capacitive (RC) loaded bow-tie antennas with special emphasis on impulse ground penetrating radar applications. Impulse radiation for ground penetrating radar is a challenging research topic because of the unique problem arising from impulse radiation: late-time ringing, which usually masks the important echo signals from the targets. While resistive loading is a common solution for eliminating late-time ringing, use of resistive loading typically sacrifices the radiation efficiency. In this thesis, a resistive-capacitive loading technique is investigated for a circular bow-tie antenna in the attempt to reduce/suppress the late-time ringing as well as to maintain a relatively high radiation efficiency. To implement the system, a microstrip differentiator, which converts a monopulse into a Gaussian-like monocycle to be used as input impulse, is presented. Further, specially designed coplanar waveguide/coplanar strip (CPW/CPS) baluns embedded with Chebyshev transformers of characteristic impedance up to 120 have been constructed and tested. To evaluate the system, instead of using the conventional peak voltage value of the radiated waveform, average radiated energy, average ringing energy, relative radiation efficiency and relative ringing efficiency are utilized and these metrics are easily established using low-cost low-sensitivity probes. Measurement results show that the RC-loading scheme is functioning as expected and the impulse system as a whole is capable of reducing the late-time ringing energy to 50% while maintaining average radiation energy as 83% when compared with capacitive loading cases. / October 2006

This thesis reports on the investigations of resistive-capacitive (RC) loaded bow-tie antennas with special emphasis on impulse ground penetrating radar applications. Impulse radiation for ground penetrating radar is a challenging research topic because of the unique problem arising from impulse radiation: late-time ringing, which usually masks the important echo signals from the targets. While resistive loading is a common solution for eliminating late-time ringing, use of resistive loading typically sacrifices the radiation efficiency. In this thesis, a resistive-capacitive loading technique is investigated for a circular bow-tie antenna in the attempt to reduce/suppress the late-time ringing as well as to maintain a relatively high radiation efficiency. To implement the system, a microstrip differentiator, which converts a monopulse into a Gaussian-like monocycle to be used as input impulse, is presented. Further, specially designed coplanar waveguide/coplanar strip (CPW/CPS) baluns embedded with Chebyshev transformers of characteristic impedance up to 120 have been constructed and tested. To evaluate the system, instead of using the conventional peak voltage value of the radiated waveform, average radiated energy, average ringing energy, relative radiation efficiency and relative ringing efficiency are utilized and these metrics are easily established using low-cost low-sensitivity probes. Measurement results show that the RC-loading scheme is functioning as expected and the impulse system as a whole is capable of reducing the late-time ringing energy to 50% while maintaining average radiation energy as 83% when compared with capacitive loading cases.

This thesis reports on the investigations of resistive-capacitive (RC) loaded bow-tie antennas with special emphasis on impulse ground penetrating radar applications. Impulse radiation for ground penetrating radar is a challenging research topic because of the unique problem arising from impulse radiation: late-time ringing, which usually masks the important echo signals from the targets. While resistive loading is a common solution for eliminating late-time ringing, use of resistive loading typically sacrifices the radiation efficiency. In this thesis, a resistive-capacitive loading technique is investigated for a circular bow-tie antenna in the attempt to reduce/suppress the late-time ringing as well as to maintain a relatively high radiation efficiency. To implement the system, a microstrip differentiator, which converts a monopulse into a Gaussian-like monocycle to be used as input impulse, is presented. Further, specially designed coplanar waveguide/coplanar strip (CPW/CPS) baluns embedded with Chebyshev transformers of characteristic impedance up to 120 have been constructed and tested. To evaluate the system, instead of using the conventional peak voltage value of the radiated waveform, average radiated energy, average ringing energy, relative radiation efficiency and relative ringing efficiency are utilized and these metrics are easily established using low-cost low-sensitivity probes. Measurement results show that the RC-loading scheme is functioning as expected and the impulse system as a whole is capable of reducing the late-time ringing energy to 50% while maintaining average radiation energy as 83% when compared with capacitive loading cases.

Tesis para optar al grado de Magíster en Gestión y Dirección de Empresas / El objetivo de la presente tesis es proponer una estandarización del análisis de riesgo de sobre costo para los proyectos de la Vicepresidencia de Proyectos de BHP en Chile, a través del diseño de un bow tie tipo, que sirva como base de análisis permitiendo así optimizar el proceso actual. El bow tie es la actual herramienta de análisis y gestión de riesgos en BHP, donde se identifican causas e impactos asociados a un riesgo, lo que permite una correcta definición de controles preventivos y mitigadores. La realización de esta tesis se justifica por los desafíos que actualmente enfrenta la minería, la necesidad de contar con la capacidad productiva suficiente para cumplir con la demanda de cobre del mundo y un precio que obliga a ser eficientes con el uso de capital. Es aquí donde la predictibilidad de costos es uno de los desafíos en la industria de proyectos, por lo que la gestión de riesgos resulta una herramienta importante para enfrentar dichos desafíos. La metodología utilizada para el desarrollo de la presente tesis comprende un levantamiento de información a partir de los análisis de riesgo y lecciones aprendidas de tres proyectos ejecutados por BHP entre los años 2012 y 2017, sumado al análisis realizado por un panel de expertos que permite caracterizar el riesgo de sobrecosto, en específico, las potenciales causas que podrían generarlo y aquellos controles que permiten prevenir su ocurrencia y/o mitigar sus potenciales impactos. Como resultado se obtienen un bow tie estandarizado para el análisis del riesgo de sobre costo. El análisis realizado tiene como resultado catorce causas, doce controles preventivos y siete controles mitigadores, cada uno de ellos es descrito para la comprensión de los futuros usuarios. Los resultados de esta tesis permiten entregar una herramienta estandarizada que identifica tempranamente las principales causas y propone una batería de controles a ser aplicados en todos los proyectos de la Vicepresidencia. La implementación de esta herramienta no considera costos adicionales dentro del área y sus potenciales beneficios se consideran importantes. Se pone a disposición el resultado de esta tesis recomendando su uso como base para futuros análisis que permita tener una base de control estándar dentro de la compañía.

Submitted by Joana Azevedo (joanad@id.uff.br) on 2017-07-03T17:09:22Z No. of bitstreams: 1 Dissert Katia Lucia da C A Ugulino.pdf: 5832202 bytes, checksum: 80dc87973043e14d4b57ed7af931bfba (MD5) / Approved for entry into archive by Biblioteca da Escola de Engenharia (bee@ndc.uff.br) on 2017-07-06T15:11:02Z (GMT) No. of bitstreams: 1 Dissert Katia Lucia da C A Ugulino.pdf: 5832202 bytes, checksum: 80dc87973043e14d4b57ed7af931bfba (MD5) / Made available in DSpace on 2017-07-06T15:11:02Z (GMT). No. of bitstreams: 1 Dissert Katia Lucia da C A Ugulino.pdf: 5832202 bytes, checksum: 80dc87973043e14d4b57ed7af931bfba (MD5) Previous issue date: 2015-12-03 / Durante o ciclo de vida de uma instalação de produção de petróleo, estão presentes riscos relacionados à segurança operacional. Na fase de operação, devido à presença de substâncias perigosas (inflamáveis, tóxicas e ou asfixiantes) submetidas a severas condições de processo, os cenários de risco são mais críticos do que nas demais fases. Nesta etapa do ciclo de vida, a gestão inadequada dos riscos de processos favorece a ocorrência de acidentes com alto potencial de danos: elevado número de fatalidades, custos com indenizações, investimentos para a recuperação de áreas contaminadas, pagamentos de multas a órgãos reguladores, perdas de continuidade operacional e consequentemente elevação do custo de produção. Estes eventos, de forma individual ou coletiva, impactam fortemente a sustentabilidade do negócio. Sendo assim, a identificação, análise e gestão destes riscos representam um grande desafio para os gestores do setor de petroquímico. Neste contexto uma das maiores dificuldades é gerenciar os riscos de processo de forma dinâmica. A abordagem proposta neste trabalho baseia-se em um sistema dinâmico de suporte a decisão que adota conceitos da Metodologia Bow Tie e do Método de Análise Hierárquica de Processo (AHP). O modelo proposto foi aplicado na forma de estudo de caso para uma única plataforma e os resultados deste piloto serão analisados a fim de ajustar os limites para alcançar o melhor desempenho em segurança de processo das instalações. / There are many process risks during the lifecycle of an oil production facility. In the operating phase due to the presence of hazardous substances (flammable, toxic and / or asphyxiating) subjected to severe process conditions, the risk scenery are more critical than in other phases. On this phase of lifecycle the inadequate process risk management favors the occurrence of accidents with high potential for damage: high number of fatalities, severance costs, investment for the rehabilitation of contaminated sites, payment of fines to regulatory agent, loss of operational continuity and consequently increase the cost of production. These events, individually or collectively, have a strong impact on business´s sustainability. Thus, the identification, analysis and process risk management in oil and gas production represents a big challenge for the managers of the petrochemical industry. In this context, one of the biggest difficulties is to manage process risks dynamically. The approach proposed in this work based on a dynamic decision support system that adopts concepts of the Bow Tie Methodology and the Hierarchical Process Analysis Method (AHP). The proposed model has been applied in a case study in a single platform and the results of this pilot will be analyze to adjust the limits to achieve the best performance of the facility process safety.

Ultra-wideband (UWB) technology and its use in imaging and sensing have drawnsignicant interest in the last two decades. Extensive studies have contributed toutilize UWB transient scattering for automated target recognition and imagingpurposes. In this thesis a near-eld UWB synthetic aperture radar (SAR) imagingalgorithm is presented.It is shown with measurements and simulation, that it is possible to reconstruct an imageof an object in the near eld region using UWB technology and SAR imaging algorithm.However the nal SAR image is highly aected by unwanted scattered elds at each pixelusually observed as an image artifact in the nal image. In this study these artifactsare seen as a smile around the main object. Two methods are suggested in this thesiswork to suppress this artifact. The rst method combines the scattered eld informationreceived from both rear and front of the object to reconstruct two separate images, onefrom rear view and one from front view of the object respectively. Since the scatteredelds from behind the object are mirrored, the pixel by pixel multiplication of thesetwo images for objects with simple geometry will cancel the artifact. This method isvery simple and fast applicable to objects with simple geometry. However this methodcannot be used for objects with rather complex geometry and boundaries. Thereforethe Range Point Migration (RPM) method is used along with the global characteristicsof the observed range map to introduce a new artifact rejection method based on thedirectional of arrival (DOA) of scattered elds at each pixel. DOA information can beused to calculate an optimum theta for each antenna. This optimum angle along withthe real physical direction of arrival at each position can produce a weighting factor thatlater can be used to suppress the eect of undesired scattered elds producing the smileshaped artifact. Final results of this study clearly show that the UWB SAR accompaniedwith DOA can produce an image of an object free of undesired artifact from scatteredeld of adjacent antennas.

Yes / The potentially broad application area in engineering design using Genetic Al- gorithm (GA) has been widely adopted by many researchers due to its high consistency and accuracy. Presented here is the initial design of a wideband non-dispersive wire bow-tie antenna using GA for breast cancer detection applications. The ultimate goal of this design is to achieve minimal late-time ringing but at higher frequencies such as that located from 4 to 8 GHz, in which is desire to penetrate human tissue for near field imaging. Resistively loading method to reduce minimal ringing caused by the antenna internal reflections is implemented and discussed when the antenna is located in free space and surrounded by lossy medium. Results with optimised antenna geometry and di®erent number of resistive loads are presented and compared with and without existence of scatterers.

We give a short introduction to various concepts related to the theory of p-harmonic functions on Rn, and some modern generalizations of these concepts to general metric spaces. The article Björn-Björn-Lehrbäck [6] serves as the starting point of our discussion. In [6], among other things, estimates of the variational capacity for thin annuli in metric spaces are given under the assumptions of a Poincaré inequality and an annular decay property. Most of the parameters in the various results of the article are proven to be sharp by counterexamples at the end of the article. The main result of this thesis is the verification of the sharpness of a parameter. At the center of our discussion will be a concrete metric subspace of weighted Rn, namely the so-called weighted bow-tie, where the weight function is assumed to be radial. A similar space was used in [6] to verify the sharpness of several parameters. We show that under the assumption that the variational p-capacity is nonzero for any ball centered at the origin, the p-Poincaré inequality holds in Rn if and only if it holds on the corresponding bow-tie Finally, we consider a concrete weight function, show that it is a Muckenhoupt A1 weight, and use this to construct a counterexample establishing the sharpness of the parameter in the above mentioned result from [6].

Un évènement Natech est un accident TECHnologique provoqué par l’impact d’un aléa NAturel sur une installation industrielle. Cet accident peut porter atteinte à l’extérieur de l’emprise du site, aux personnes, aux biens ou à l’environnement. L’objectif de ce travail est de mettre au point une méthodologie pour l’analyse et la prévention du risque d’accidents technologiques induits par l’inondation (Natech inondation) d’un site industriel. La méthodologie repose, dans un premier temps, sur une étude des Retours d’Expériences. Il a été identifié que les accidents Natech sont imputables à un rejet de matières dangereuses sur des équipements dits critiques endommagés directement ou indirectement par les eaux d’inondation. Les rejets de matières dangereuses vont amener à trois types d’accidents (incendie, pollution, explosion). Dans un deuxième temps, la méthode MADS-MOSAR a été adaptée à l’application aux accidents Natech inondation. L’analyse a abouti à cinq scénarios génériques d’accident Natech inondation sous forme de cinq nœuds papillons. Une soixantaine de Mesures de Maîtrise de Risque de prévention et de protection ont été identifiées. La validation de la complétude et de la plausibilité des nœuds papillons génériques est effectuée, d’une part, à l’échelle du secteur d’activité de traitement de surface et, d’autre part, à l’échelle spécifique d’établissements industriels. Ce travail a abouti à un outil de diagnostic de la vulnérabilité d’une installation industrielle aux accidents Natech inondation, accompagné d’un catalogue de MMR. Enfin, ce diagnostic a été appliqué sur un site industriel afin d’évaluer son mode opératoire et de l’enrichir par l’expérimentation. / A Natech accident is the impact of a NAtural event on an industrial plant (such as an ICPE- Classified Installation for the Environmental Protection). The impact can trigger a TECHnological accident, damaging the vicinity of the industrial facility (inhabitants, their properties and the environment). The final objective of this work is to develop a risk analysis methodology for the prevention of technological accidents triggered by flooding of industrial facilities. Therefore, the work begins with an analysis of past technological accidents triggered by floods. Thus, it was identified that Natech accidents are the consequences of hazardous materials releases from critical equipment, which in turn are damaged directly and indirectly by flood waters. Depending on the type of hazardous substances released, three categories of technological accidents are observed (fire, pollution and explosion). Afterwards, a risk analysis methodology was developed. It is mainly based on the MADS-MOSAR method, which was modified in order to be adapted to the Natech issue. The analysis resulted in the identification of five generic scenarios of technological accidents triggered by floods that can occur within an industrial installation. These scenarios were represented using the bow-tie tool. Then, around sixty preventive and protective measures were identified. The validation of the elaborated scenarios was done, on one hand, in the surface treatment industrial sector and, on the other hand, in two specific industrial facilities. The validation phase helped to test the completeness and plausibility of the generic scenarios, as well as the relevance of the measures previously identified. Furthermore, the validated scenarios were used to develop a checklist helping operators to decrease the vulnerability of their industrial facilities to technological accidents triggered by floods, along with a catalog of preventive and protective measures. Finally, the tool was applied to an industrial installation in order to enhance it and test its relevance by operators.

This thesis describes design and experimental verification of three types of the wideband antenna Bow-tie antenna, Vivaldi antenna and Spiral antenna. The tracked parameters are bandwidth, input impedance, gain and directivity patterns. Next step is design of millimeter-wave horn antennas. Attention is turned to the proper construction of a wideband feeder of the horn. For the final antenna structure, a bow-tie dipole and a Vivaldi antenna were chosen. The antenna construction is aimed to provide a wide bandwidth on one hand and a high gain on the other hand.