A operação segura e eficiente em unidades de produção de petróleo e gás depende do desempenho de seus dispositivos, componentes e estruturas. Dutos rígidos são importantes componentes utilizados na indústria offshore, comumente empregados como flowlines e risers. Durante a vida em serviço destes componentes, eles sofrem tensões axiais cíclicas associadas a sua movimentação, ao processo de extração de petróleo e ao vórtice das marés. O aço inoxidável superduplex surgiu na última década como um material alternativo para ambientes quimicamente agressivos, mas quando catodicamente protegidos contra a corrosão, esses aços são vulneráveis a fragilização por hidrogênio. Este trabalho tem como objetivo, através da técnica de Ensaio Não Destrutivo de ultrassom phased array, monitorar o crescimento de defeitos internos e externos criados intencionalmente próximos à raiz e ao reforço da solda de um tubo de aço superduplex (UNS S32750) de 6´´ submetido a fadiga tração-tração e fragilização induzida por hidrogênio devido à proteção catódica. As inspeções foram realizadas periodicamente com varreduras de 30 a 75° ao longo da circunferência da solda, por um transdutor linear 1-D de 16 elementos e 5MHz acoplado a uma sapata de 36°. Os resultados obtidos foram utilizados para alimentar análises de integridade estrutural, obtenção da curva da/dN x ΔK. / Safe and efficient operation in oil and gas production units depends on the performance of your devices, components and structures. Rigid pipelines are important components in the offshore industry, common used as flowlines and risers. During a life in service of components, they suffer cyclical axial stresses associated with their movement, by the oil extraction process and tidal vortex. Super duplex stainless steel has emerged in the last decade as an alternative material for chemically aggressive environments, but when cathodically protected against corrosion, it is vulnerable to hydrogen embrittlement. This work aims to, through the ultrasonic non-destructive testing by phased array monitor the growth of internal and external defects created intentionally close to the root and reinforcement of the weld of a superduplex steel tube (UNS S32750) with diameter of 6" submitted to tensile-traction fatigue and hydrogen-induced embrittlement due to cathodic protection. The inspections were performed periodically with 30 to 75° scans along the circumference of the weld, by a linear transducer of 1-D, 16-element and 5MHz coupled to a wedge of 36°. The obtained results were used to feed structural integrity analyzes, obtaining the curve of da/dN x ΔK.

Componentes metálicos em operação podem estar sujeitos a diversas condições de operação deletérias. Visando avaliar os riscos de operação para evitar falhas, a análise de integridade estrutural é uma ferramenta amplamente aplicada e requer constante evolução. Por utilizar dados de ensaios não destrutivos, essa ferramenta requer cada vez mais precisão, para aprimorar seus resultados e reduzir ao máximo as falhas de componentes em operação. Por apresentar menor tempo de inspeção e maior probabilidade de detecção, o Phased Array surge como alternativa às técnicas convencionais de ultrassom. Dentre as técnicas de Phased Array, o Total Focusing Method (TFM) apresenta um dos resultados mais promissores, apresentando grande vantagem sobre técnicas convencionais de ultrassom e de Phased Array devido a sua melhor precisão e fácil interpretação dos resultados. Neste trabalho, o TFM foi aplicado em diversos blocos contendo descontinuidades usinadas, as quais simulam diferentes tipos de defeitos. O foco do TFM foi gerar blocos em três dimensões (3D) dos defeitos, facilitando a interpretação dos resultados, além da possibilidade da inserção desses blocos em softwares de análise de integridade estrutural, melhorando a precisão dos resultados. O TFM foi aplicado através do tratamento de dados de um sensor linear de Phased Array, com frequência de 5 MHz e com 64 elementos ativos. Nesse trabalho, foram desenvolvidas e aplicadas novas etapas no algoritmo do TFM para melhorar a precisão dos resultados, como a compensação da perda de energia e o half-skip. As etapas adicionais aplicadas ao algoritmo do TFM geraram bons resultados para entalhe e furos usinados nos blocos de aço carbono. Além dos blocos com defeitos usinados, foi realizada a inspeção de um bloco de aço inoxidável austenítico soldado. Para o bloco soldado, os resultados não foram satisfatórios, não sendo possível detectar defeitos existentes. Após a aplicação do TFM, foi simulado o deslocamento do sensor ao longo da peça, gerando diversas imagens 2D, as quais foram conectadas via isosuperfícies, gerando sólidos 3D dos defeitos presentes em cada bloco. Por fim, esses blocos foram exportados para um software CAD, apresentando excelente correspondência. / Metallic components in operation can be submitted to several harming operation conditions. Aiming to evaluate the operational risks to avoid failure, the structural integrity analysis is a widely applied tool and requires constant evolution. As it uses non-destructive testing data, this tool requires increasingly precision, to enhance its results and reduce the majority of the operating components failures. Because of the shorter inspection time and greater probability of detection, Phased Array is an alternative to conventional ultrasonic techniques. Among the techniques of Phased Array, the Total Focusing Method (TFM) presents one of the most promising results, offering great advantage over conventional ultrasonic and Phased Array techniques due to its better precision and easy interpretation of results. In this work, the TFM was applied to many blocks, which contain machined discontinuities simulating several defects. The objective of applying the TFM was to generate three-dimensional (3D) blocks, turning the interpretation of the results easier and giving the possibility to insert these blocks into a structural integrity analysis software, enhancing the results precision. The TFM algorithm was applied through treatment of data from a 5 MHz linear Phased Array sensor with 64 active elements. In this work, it were developed and applied new steps in the TFM algorithm, as energy loss compensation and half-skip interaction, to improve its precision. The additional steps applied to the TFM algorithm achieved great results for notch and holes machined in carbon steel blocks. In addition to the blocks with machined defects, a welded austenitic stainless steel block was inspected. For the welded block, the results were not satisfactory and it was not possible to detect the present defects. After the application of the TFM, the displacement of the transducer along the block was simulated, generating several 2D images, which were connected via isosurfaces, generating 3D solids corresponding to the defects present in each block. To conclude, these blocks were exported to a CAD software, presenting excellent matching.

<p>The objective of this research is to develop recommendations on calibration standards, scanning procedures, and acceptance criteria for phased array ultrasonic testing (PAUT) of complete joint penetration butt welds within the AWS D1.5 Bridge Welding Code. These recommendations include the development of a rational acceptance criteria which is based in engineering analysis and fracture mechanics. It is expected that the updated scanning procedures and acceptance criteria will result in improved reliability for bridges and improved consistency in bridge fabrication quality.</p><p><br></p> <p> </p> <p>While PAUT was included in the 2015 edition of AWS D1.5 in Annex K, the acceptance criteria for this procedure was developed as an adaptation of an existing conventional ultrasonic testing (UT) acceptance criteria in AWS D1.1. Therefore, the acceptance criteria in AWS D1.5:2015 is a workmanship-based criteria and is not based on engineering analysis of the criticality of weld flaws. The scanning procedures and application of PAUT inspections of bridge welds according to this procedure differ greatly from the scanning procedures outlined in AWS D1.5 for conventional UT inspections. Previous research has shown that differences in flaw rejection are possible for PAUT and conventional UT ultrasonic methods under the AWS D1.5:2015 approach.</p><p><br></p> <p> </p> <p>In order to develop recommendations for improved calibration standards, scanning procedures, and acceptance criteria for PAUT within AWS D1.5, this research project utilized both analytical techniques and experimental testing. This research project included determination of target critical flaw sizes for routine detection and rejection through fitness-for-service evaluations. This was followed by a round robin ultrasonic testing program in order to collect data on the variability of inspection results of eleven weld samples with nineteen weld flaws using different ultrasonic inspection techniques. Next, calibration requirements were developed to account for differences in ultrasonic attenuation and shear wave velocity between calibration blocks and test objects. Development of these requirements included experimental testing of base metals and weld metals, along with simulations of ultrasonic inspection using commercial software. Finally, minimum requirements for weld scanning procedures, reference standard reflectors, and corresponding amplitude limits for detection and rejection of target critical weld flaws were developed using ultrasonic inspection simulations and verified through experimental testing of weld samples with known weld flaws.</p>

Focused ultrasound surgery (FUS) is considered as a promising approach for treating cancer and other conditions and is gaining increasing interest. However, the limited availability of experimental ultrasound array sources and multichannel electronics able to drive them hinder the research into FUS system configurations for patient conditions such as breast cancer. The work in this dissertation explored the development of ultrasound arrays for MRI guided FUS, from the point of view of the potential piezoelectric material of choice. Two materials are of particular interests in this work: Binary (x)Pb(Mg1/3Nb2/3) O3 - (1-x)PbTiO3 (PMN-PT) piezocrystal, and newly specialized FUS material, PZ54 ceramic. A characterization methodology was developed to fully characterize the materials of choice, under ambient and extreme conditions relevant to FUS applications. Practicalities of adopting these materials into FUS were studied by using the characterized materials in designing and fabricating FUS arrays. A spherical, faceted array geometry inspired by the geodesic dome structure was proposed and implemented for the first time. Four bespoke devices, each with 96 individual elements, were implemented using PZ26 ceramic, PZ26 composite, PZ54 composite and PMN-PT composite materials, respectively for comparison. The arrays were connected to commercial electronics afterwards, to explore a prototyping route for connecting FUS devices and modular driving systems. It is concluded that PMN-PT piezocrystal and PZ54 ceramic material can offer excellent performance over conventional piezoelectric ceramics, although PMN-PT piezocrystal is sensitive to extreme conditions. The usable range of PMN-PT is suggested to be limited to 60°C in temperature and 10 MPa in pressure. However, PMN-PT piezocrystal could still be a potential alternative to conventional ceramics in FUS application if assisted with sufficient cooling circulation and bias field. The geodesic array geometry is also concluded to be able to achieve good focusing of ultrasound beam. With optimized phase control through multi-channel electronics, the focusing was improved with focusing gain up to about 30; the steering range of focus was explored within a volume of 5 x 5 x 10 mm3 beyond the array’s geometric focus, side lobes were limited to below the level of -9 dB in acoustic intensity. Larger numbers of individual controllable elements and alternative array designs will be explored in future to investigate application such as breast cancer treatment and potential pre-clinical trials.

As small unmanned aerial systems (UAS) are introduced into the national airspace, measures must be introduced to ensure that they do not interfere with manned aviation and other UAS. Radar provides an attractive solution because of its inherent range accuracy and because it works in diverse weather and lighting conditions. Traditional radar systems, however, are large and high power and do not meet the size, weight and power (SWaP) constraints imposed by UAS, and fully integrated automotive solution do not provide the necessary range. This thesis proposes a compact radar system that meets both the SWaP and range requirements for UAS and can act as a standalone sensor for a sense and avoid system (SAA). The system meets the field of view requirements motivated by the UAS sensing problem (120deg x 30deg) and tracks targets in range and azimuthal angle using a four element phased array receiver. The phased array receiver implements real time correlation and beamforming using a field programmable gate array (FPGA) and can track multiple targets simultaneously. Excluding antennas, the radar transceiver and signal processing platform weighs approximately 120g and is approximately the size of a whiteboard eraser (2.25in x 4in x 1in), which meets the payload requirements of many small (<25kg) UAS. To our knowledge, this is the first real time phased array radar that meets the sensing and SWaP requirements for small UAS.Our testing was done with the radar system on the ground, aimed at airborne UAS targets. Using antennas with a gain of 12 dB, and 800 milliwatts of transmitted power, the system detects UAS targets with a radar cross section of less than 0.1 square meters up to 150 meters away. The ground based system demonstrates radar detectability of extremely small UAS targets, and is scalable to further ranges by increasing antenna gain or adding additional elements. Based on our success in detecting airborne UAS, we conclude that radar remains a feasible option for a UAS collision avoidance sensor.

A phased array feed (PAF) provides a contiguous, electronically synthesized wide field of view for large-dish astronomical observatories. Significant progress has been made in recent years in improving the sensitivity of PAF receivers though optimizing the design of the antenna array, cryogenic cooling of the front end, and implementation of real-time correlation and beamforming in digital signal processing. FLAG is a 19 dual-polarized element phased array with cryogenic LNAs, direct digitization of RF signals at the front end, digital signal transport over fiber, and a real time signal processing back end with up to 150 MHz bandwidth. The digital back end includes multiple processing modes, including real-time beamforming, real-time correlation, and a separate real-time beamformer for commensal radio transient searches. Following a polyphase filterbank operation performed in field programmable gate arrays (FPGAs), beamforming, correlation, and integration are implemented on graphical processing units (GPUs) that perform parallelized operations. Parallelization greatly increases processing speed and allows for real-time signal processing. During a recent test/commissioning of FLAG, Tsys/efficiency of approximately 28 K was measured across the PAF field of view and operating bandwidth, corresponding to a system temperature below 20 K. To demonstrate the astronomical capability of the receiver, a pulsar (PSR B1937+21) was detected with the real-time beamformer. This thesis provides details on the development of the FLAG digital back end, the real-time beamformer, and reports on the commissioning tests of the FLAG PAF receiver developed by the National Radio Astronomy Observatory (NRAO), Green Bank Observatory (GBO), West Virginia University (WVU), and Brigham Young University for the Green Bank Telescope (GBT).

A true time delay multi-bit MEMS phase shifter topology based on impedance-matched slow-wave CPW sections on a 500µm thick quartz substrate is presented. Design equations based on the approximate model for a distributed line is derived and used in optimization of the unit cell parameters. A semi-lumped model for the unit cell is derived and its equivalent circuit parameters are extracted from measurement and EM simulation data. This unit cell model can be cascaded to accurately predict N-section phase shifter performance. Experimental data for a 4.6mm long 4-bit device shows a maximum phase error of 5.5° and S11 less than -21dB from 1-50GHz. A reconfigurable MEMS transmission line based on cascaded capacitors and slow-wave sections has been developed to provide independent Zo - and β-tuning. In the Zo-mode of operation, a 7.4mm long line provides Zo-tuning from 52 to 40Ω (+/-2Ω) with constant phase between the states through 50GHz. The same transmission line is reconfigured by addressing the MEM elements differently and experimental data for a 1-bit version shows 358°/dB (or 58°/mm) with S11 less than -25dB at 50GHz. The combined effect of Zo- and β-tuning is also realized using a 5-bit version. An electronically tunable TRL calibration set that utilizes a 4-bit true time delay MEMS phase shifter topology, is demonstrated. The accuracy of the tunable TRL is close to a conventional multi-line TRL calibration and shows a maximum error bound of 0.12 at 40GHz. The Tunable TRL method provides for an efficient usage of wafer area while retaining the accuracy associated with the TRL technique, and reduces the number of probe placements.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第24147号 / 工博第5034号 / 新制||工||1786(附属図書館) / 京都大学大学院工学研究科電気工学専攻 / (主査)教授 篠原 真毅, 教授 小嶋 浩嗣, 教授 山本 衛 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

The main focus of the work presented in this licentiate thesis concerns antenna design, adaptive antenna control and investigation on how the performance of small wireless nodes can be increased by inclusion of multiple antennas. In order to provide an end-user suitable solution for wireless nodes the devices require both small form factor and good performance in order to be competitive on the marked and thus the main part of this thesis focuses on techniques developed to achieve these goals. Two prototype systems have been developed where one has been used by National Defence Research Agency (FOI) to successfully monitor a test-subject moving in an outdoor terrain. The other prototype system shows the overall performance gain achievable in a wireless sensor node when multiple antennas and antenna beam steering is used. As an example of how to include multiple antennas in a wireless node the concept of using dual conformal patch antennas for wireless nodes is presented. The proposed antenna showed an excess of 10 dB gain when using a single driven antenna element as would be the case in a system utilizing antenna selection combining. When used as a 2-element phased array, up to 19 dB gain was obtained in a multiscattering environment. Using the second order resonance the proposed antenna structure achieves low mutual coupling and a reflection coefficient lower than -15 dB. The presented antenna design shows how a dual antenna wireless node can be designed using discrete phase control with passive matching which provides a good adaptive antenna solution usable for wireless sensor networks. The inclusion of discrete phase sweep diversity in a wireless node has been evaluated and shown to provide a significant diversity gain. The diversity gain of a discrete phase sweep diversity based system was measured in both a reverberation chamber and a real life office environment. The former environment showed between 5.5 to 10.3 dB diversity gain depending on the detector architecture and the latter showed a diversity gain ranging from 1 to 5.4 dB. Also the performance of nodes designed to be placed in a high temperature and multiscattering environment (the fan stage of a jet engine) has been evaluated. The work was carried out in order to verify that a wireless sensor network is able to operate in such a multiscattering environment. It was shown that the wireless nodes are able to operate in an emulated turbine environment based on real-life measured turbine fading data. The tested sensor network was able to transmit 32 byte packages using cyclic redundancy check at 2 Mbps at an engine speed of 13.000 rpm. / WISENET / WISEJET

Ever growing demands for higher data rate and bandwidth are pushing extremely high data rate wireless applications to millimeter-wave band (30-300GHz), where sufficient bandwidth is available and high data rate wireless can be achieved without using complex modulation schemes. In addition to the communication applications, millimeter-wave band has enabled novel short range and long range radar sensors for automotive as well as high resolution imaging systems for medical and security. Small size, high gain antennas, unlicensed and worldwide availability of released bands for communication and a number of other applications are other advantages of the millimeter-wave band. The major obstacle for the wide deployment of commercial wireless and radar systems in this frequency range is the high cost and bulky nature of existing GaAs- and InP-based solutions. In recent years, with the rapid scaling and development of the silicon-based integrated circuit technologies such as CMOS and SiGe, low cost technologies have shown acceptable millimeter-wave performance, which can enable highly integrated millimeter-wave radio devices and reduce the cost significantly. Furthermore, at this range of frequencies, on-chip antenna becomes feasible and can be considered as an attractive solution that can further reduce the cost and complexity of the radio package. The propagation channel challenges for the realization of low cost and reliable silicon-based communication devices at millimeter-wave band are severe path loss as well as shadowing loss of human body. Silicon technology challenges are low-Q passive components, low breakdown voltage of active devices, and low efficiency of on-chip antennas. The main objective of this thesis is to investigate and to develop antenna and front-end for cost-effective silicon based millimeter-wave phased array radio architectures that can address above challenges for short range, high data rate wireless communication as well as radar applications. Although the proposed concepts and the results obtained in this research are general, as an important example, the application focus in this research is placed on the radio aspects of emerging 60 GHz communication system. For this particular but extremely important case, various aspects of the technology including standard, architecture, antenna options and indoor propagation channel at presence of a human body are studied. On-chip dielectric resonator antenna as a radiation efficiency improvement technique for an on-chip antenna on low resistivity silicon is presented, developed and proved by measurement. Radiation efficiency of about 50% was measured which is a significant improvement in the radiation efficiency of on-chip antennas. Also as a further step, integration of the proposed high efficiency antenna with an amplifier in transmit and receive configurations at 30 GHz is successfully demonstrated. For the implementation of a low cost millimeter-wave array antenna, miniaturized, and efficient antenna structures in a new integrated passive device technology using high resistivity silicon are designed and developed. Front-end circuit blocks such as variable gain LNA, continuous passive and active phase shifters are investigated, designed and developed for a 60GHz phased array radio in CMOS technology. Finally, two-element CMOS phased array front-ends based on passive and active phase shifting architectures are proposed, developed and compared.