The Supercritical Fluid Extraction (SFE) technique was used to fractionate Suwannee River reference fulvic acid (FA). The fractions were characterized by gas chromatography (GC) and reversed-phase high performance liquid chromatography (RP-HPLC). A SFE fractionation method was developed using stepwise gradient of supercritical CO₂ and methanol. Three FA fractions were separated. The average mass recovery was 102% with the coefficient of variation of 2.8%. The fractionation dynamics and the difference in the ratios of UV absorption to fluorescence emission indicate the real fractionation of the FA. The HPLC chromatographic peak patterns and the spectra of the corresponding peaks were almost indistinguishable. The overall results of this research support the argument that FA exhibits polymer-like molecular structure.

Phased array radar systems employ multiple antennas to create a radar beam that can be steered electronically. By manipulating the relative phase values of feeding signals among different antennas, the effective radiation pattern of the array can be synthesized to enhance the main lobe in a desired direction while suppressing the undesired side lobes in other directions. Hence the radar scanning angles can be electronically controlled without employing the bulky mechanical gimbal structure, which can significantly reduce radar system size, weight and power consumption. In recent years, phased array technologies have received great attentions and are explored in developing many new applications, such as smart communication systems, military radars, vehicular radar, etc. Most of these systems are narrow band systems, where the phase delays are realized with narrow band phase shifter circuits. For the impulse ground penetrating radar however, its operating frequency spans an ultrawide bandwidth. Therefore the traditional phase shifters are not applicable due to their narrow band nature. To resolve the issue, in this study, a true time delay approach is explored which can precisely control time delays for the feeding pulse signals among different antennas in the array. In the design, an on chip programmable delay generator is being developed using Global Foundry 0.18 µm 7 HV high voltage CMOS process. The time delay control is realized by designing a programmable phase locked loop (PLL) circuit which can generate true time delays ranging from 100 ps (picoseconds) to 500 ps with the step size of 25 ps. The PLL oscillator's frequency is programmable from 100MHz to 500MHz through two reconfigurable frequency dividers in the feedback loop. As a result, the antenna beam angle can be synthesized to change from 9.59° to 56.4° with a step of 2.75°, and the 3dB beamwidth is 10°. The power consumption of the time delay circuit is very low, where the supply voltage is 1.8V and the average current is as low as 472uA.

The thesis presents a compact, miniature, and low cost antenna array designed for millimeter-wave frequencies for future 5th generation (5G) mobile applications. The proposed antenna array is a geometrically modified structure of the Franklin array, which allowed to transform a conventional narrowband array into a wideband antenna array. It is composed of five millimetre-wave circular patch radiation elements with phasing stubs. The designed array, fabricated on the commercial Rogers RO3003 substrate with small form factor of 8x25x0.5 mm3, covers the upcoming 5G band of 23.6-30.3 GHz, with peak gain as 10.8 dB, and high radiation efficiency over the whole operating band. In addition, with frequency sweeping, the proposed antenna array radiation pattern is directive and offers beam steering at the desired angles, acting similarly as a leaky-wave antenna.

This thesis studies the possibility to replace the global navigation satellite system (GNSS) with a phased array radio system (PARS) for positioning and navigation of an unmanned aerial vehicle (UAV). With the increase of UAVs in both civilian and military applications, the need for a robust and accurate navigation solution has increased. The GNSS is the main solution of today for UAV navigation and positioning. However, the GNSS can be disturbed by malicious sources, the signal can either be blocked by jamming or modified to give the wrong position by spoofing. Studies have been conducted to replace or support the GNSS measurements with other drift free measurements, e.g. camera or radar systems. The position measurements from PARS alone is shown not to provide sufficient quality for the application in mind. The PARS measurements are affected by noise and outliers. Reflections from the ground makes the PARS elevation measurements unusable for this application. A root mean square error (RMSE) accuracy of 10 m for a shorter flight and 198 m for a longer flight are achieved in the horizontal plane. The decrease in accuracy for the longer flight is assumed to come from a range bias that increases with distance due to the flat earth approximation used as the navigation frame. Positioning based on PARS aided with a filter and other GNSS independent sensors is shown to reduce the noise and remove the outliers. Five filters are derived and evaluated: a constant velocity extended Kalman filter (EKF), an inertial measurement unit (IMU) aided EKF, an IMU and barometer aided EKF, a converted measurements Kalman filter (CMKF) and a stationary Kalman filter (KF). The IMU and barometer aided EKF performed the best results with a RMSE of 8 m for a shorter flight and 106 m for a longer flight. The noise is significantly reduced compared to the standalone PARS measurements. The conclusion is that PARS can be used as a redundancy system with the IMU and barometer aided EKF. If the EKF algorithm is too computational demanding, the simpler stationary KF can be motivated since the accuracy is similar to the EKF. The GNSS solution should still be used as the primary navigation solution as it is more accurate.

O trabalho apresentado nesta dissertação é referente ao estudo da evacuação de pessoas, mais especificamente, a evacuação predial faseada. O objetivo é determinar, para instâncias de até 25 andares, os instantes de liberação de cada grupo de pessoas, a fim de minimizar o tempo total de evacuação do edifício. No entanto, a determinação destes instantes deve considerar o risco ao qual os diferentes grupos estão submetidos, priorizando a evacuação do andar afetado. Além disso, os conflitos de diferentes grupos por espaço nas rotas de evacuação também devem ser evitados, já que, são nessas situações que acontecem grande parte dos acidentes. Para atingir tal objetivo, foi elaborado um modelo matemático de programação linear inteira. Devido à alta complexidade do modelo, fez-se necessária a aplicação de métodos heurísticos para a obtenção de soluções. Dessa maneira, foram desenvolvidas uma heurística de busca baseada em GRASP e uma heurística lagrangeana. Apesar da heurística lagrangeana atestar a qualidade da solução (a partir da comparação do resultado obtido com o limitante inferior), a heurística de busca mostrou-se mais adequada para o problema, pois forneceu resultados de qualidade com pouco esforço computacional. / This dissertation studies the evacuation of people, more specifically, building phased evacuation. The objective of this study is to determine, for buildings of up to 25 floors, in which instants each group of people has to be released, in order to minimize the total evacuation time. Furthermore, the determination of these instants has to consider the risk to which each group of people is submitted, thus the affected floor has to be the first group to be released. In addition, conflicts for space between groups should be avoided, since such situations increase the occurrences of accidents. To achieve this goal, an integer linear programming model was designed. Due to the high complexity of the model, it was necessary to apply heuristics to obtain solutions for some instances. Therefore, a search heuristic based on GRASP and a lagrangian heuristic were developed. Despite the fact that the lagrangian heuristic attests to the quality of the solution (when it is compared to the lower bound), the search heuristic was considered more suitable for this problem because it provided quality results with lower computational efforts.

Este trabalho apresenta o projeto de uma portadora que opera na frequência de 8.300 MHz para ser utilizado em moduladores vetoriais diretos com aplicação em sistemas embarcados de satélites. Foram realizados estudos sistêmicos de arquiteturas que operam nesta faixa de frequência com as características necessárias para atender as especificações da European Cooperation for Space Standardization, ECSS - Space Engineering Radio Frequency and Modulation da agência espacial europeia -ESA, que regulamenta as frequências e características para sistemas de transmissão para enlace de descida. A partir dos conhecimentos adquiridos nos estudos, é apresentada uma metodologia de projeto visando o atendimento das especificações definidas pela ECSS e a escolha de uma topologia de projeto. Foram realizadas simulações a nível sistêmico, utilizando o software Advanced Design System-ADS da fabricante Keysight Technologies, para definir as especificações de projeto dos circuitos que compõem o sistema de geração da portadora na banda X. O circuito da malha de sincronismo de fase - PLL opera na frequência de 2.075 MHz, onde seu sinal é amplificado e filtrado pela cadeia de amplificação na banda S cuja função é aumentar a isolação para minimizar os efeitos de pulling do oscilador controlado por tensão - VCO, devido à alta velocidade nas transições de tempo de subida e de descida dos sinais digitais I e Q. O filtro também é responsável por aumentar a rejeição de espúrios e harmônicos gerados pelos efeitos não lineares dos amplificadores. O sinal é enviado ao circuito multiplicador de frequências que gera o sinal na banda X e é filtrado por um filtro passa-faixas de linhas acopladas, rejeitando os sinais espúrios provenientes da saída do multiplicador de frequência. Na saída, o sinal passa por uma cadeia de amplificação na banda X para adequar o nível de potência à entrada dos moduladores vetoriais. Os circuitos projetados foram desenvolvidos utilizando tecnologia de microfita de linha. Os protótipos foram caracterizados, apresentando boa concordância com os resultados simulados, comprovando experimentalmente a metodologia de projeto utilizada neste trabalho assim como o atendimento das especificações sugeridas pela ECSS. / This work presents the project of an carrier that works in the frequency of 8,300 MHz to be used in direct vector modulator for embedded system application in satellites. It were realized system level studies of PLL topologies that work in this frequency range with the necessary features to provide the requirements from European Cooperation for Space Standardization, ECSS - Space Engineering Radio Frequency and Modulation of the European Space Agency - ESA, which is responsible for the frequencies and features regulation for downlink transmission system. With the knowledge acquired from the studies, it is presented a project method intending to the meet the requirements defined by the ECSS and the definition of a topology to the project. It were performed system level simulation, using the Advanced Design System - ADS tool, from Keysight Technologies, in order to define the design specifications in the project of the circuits of the X band carrier generator developed. The PLL circuit works in the frequency of 2,075 MHz, in which its signal is amplified and filtered for amplifier chain in S band, increasing the isolation to reduce the pulling effects in the voltage controlled oscillator, due to the high-speed transitions in the rise time and fall time of the digital signal I and Q. The filter is also responsible for increasing the rejection of spurious and harmonics generated by non-linear amplifiers effects. The signal is conducted to the frequency multiplier circuit that generates the X band signal and it is filtered by a coupled line bandpass filter, rejecting the spurious from the frequency multiplier output. At the output stage, the signal passes through a X band amplification chain in order to adequate the power level of the vector modulators input level. The specified circuits were designed and developed using microstrip line technology. The prototypes were characterized, presenting adequate results according to the data obtained by the simulations, experimentally reinforcing the project method used in this work as well as the meeting of the requirements suggested by the ECSS.

近十年來，無線通訊技術、流動電話服務以及無線網絡的發展一日千里。不單止為社會帶來很多新的技術及先進的設備，更加帶來了許多新穎的應用構想。其中最被廣泛討論的要數室內無線實時定位系統。室內定位，顧名思義就是一種對一個或多個室內目標進行定位及追蹤的技術。這種技術的潛在應用非常多元化，例如倉庫管理、人力資源調配等等。透過這種技術可以使一些室內位置信息相關的服務更加自動化，從而提升服務效率。正因為市場狂熱的需求，近年來室內無線實時定位系統一直都是一個熱門的研究課題。 / 本論文的上半部主要是討論一種基於無線射頻識別技術的室內無線實時定位系統。這個系統的特點是在閱讀器的天線上應用了模擬一維綫相控陣列天線。系統的定位原理是基於三角測距法，透過相控陣的主波束掃描配合信號強度測量去估算出信號入射角。比較其他入射角測量的方法，應用這種方法的硬件成本更低而且能確保一定的精度。整個系統的開發包括有無線射頻標籤、閱讀器、模擬一維綫相控陣列天線、網絡控制器、數據庫、圖像應用界面及一種有效壓抑室內多徑問題的定位算法。這個系統的最大好處就是它不像其他一些現存的定位系統一樣，在安裝後需要進行大量的離線實地校準。我們進行了大量的實驗去客觀地驗證系統的定位性能，實驗的結果指出系統的定位誤差平均值小於一米。 / 為了控制系統的硬件成本，上述所提及到的模擬一維綫相控陣列天線會採用一種非常便宜的板材：FR4。但是FR4這種板材便宜的代價便是它相對較高的介質損耗。較高的介質損耗對模擬一維綫相控陣列天線的實現存在着一個重要的難題：模擬360º移相器的插入損耗相對電壓變化不平滑。有見及止，本論文的下半部會討論一種新穎而有效壓抑因高介質損耗而導致插入損耗不平滑的反射式移相器。新的移相器設計包含兩種壓抑插入損耗不平滑的技術。在仿真結果中，新的設計把傳統設計的插入損耗不平滑從1.4分貝大幅降低至0.3分貝。實驗的結果指出，在360o 的移相範圍內只存在着0.6分貝的插入損耗不平滑。 / 最後在此作一個總結。本論文主要是討論一種高效、低成本、基於無線射頻識別技術及模擬一維綫相控陣列天線技術的室內無線實時定位系統。大量的實驗數據證明了它良好的定位性能。而且系統的網絡設計使到它可以更彈性地應用到不同的場所。 / In recent years, the rapid development in wireless communication technologies, mobile computing devices and wireless networks has stimulated a fast growing interest in various location-aware systems that can provide real time information of physical locations of objects or persons. In this thesis, an active radio frequency identification (RFID) indoor positioning system utilizing analog linear phased array antenna (PAA) technology has been proposed and demonstrated. By using beam steering of an analog linear PAA and measuring the corresponding received signal strength indicator (RSSI), one can determine the angle of arrival (AoA) of the transmitted signal from a tag. In this work, a complete locationing system has been built, which includes RFID tag, reader integrated PAA, network controller and database with event driven functions. Besides that, a novel positioning algorithm that can effectively overcome indoor multipath effect is also proposed. The major advantage of the proposed system is that it doesn’t require any on-site calibration. Therefore, the setup of the proposed system is scenario-independent. A large number of experiments and results have demonstrated that the probabilities of spatial errors of less than 1 meter and 1.5 meters of the proposed system are about 80% and 95% respectively. / In order to have a cost-effective system, those analog linear PAAs are fabricated in FR4 substrate, with which constant insertion loss under phase steering of a 360º analog phase shifter is difficult to realize due to the substrate loss. In order to overcome this difficulty, a novel loss-compensated microstrip 360º reflection-type diode phase shifter with constant insertion loss has been proposed and concept proven. In this regard, two techniques have been investigated to reduce the insertion loss variation which is caused by using lossy substrate. As compared with the conventional design, simulation results have shown a considerable improvement on the insertion loss variation from 1.4dB to 0.3dB. Measurement results have demonstrated a 0.6dB insertion loss variation over 360º phase steering range. / In conclusion, a low-cost but with moderate performance RFID indoor locationing system based on analog linear PAA technology has been proposed and experimentally demonstrated. The prototype system has shown its high accuracy, flexibility in network deployment, and scenario-independent operation. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Hung, Wing Hung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 85-87). / Abstracts also in Chinese. / ABSTRACT --- p.I / 論文摘要 --- p.III / ACKNOWLEDGEMENT --- p.V / TABLE OF CONTENT --- p.VI / LIST OF FIGURES --- p.IX / LIST OF TABLES --- p.XIII / LIST OF ABBREVIATIONS --- p.XIV / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter 1.1. --- RESEARCH MOTIVATION --- p.1 / Chapter 1.2. --- OVERVIEW OF THE THESIS ORGANIZATION --- p.5 / Chapter CHAPTER 2 --- FUNDAMENTALS IN LINEAR PHASED ARRAY ANTENNA AND REFLECTION-TYPE PHASE SHIFTER --- p.6 / Chapter 2.1. --- LINEAR PHASED ARRAY ANTENNA --- p.6 / Chapter 2.1.1. --- Operating Principle --- p.7 / Chapter 2.1.2. --- Simulation Example --- p.9 / Chapter 2.2. --- REFLECTION-TYPE PHASE SHIFTER --- p.10 / Chapter 2.2.1. --- Operating Principle --- p.10 / Chapter 2.2.2. --- Simulation Example --- p.12 / Chapter CHAPTER 3 --- CONVENTIONAL INDOOR POSITIONING METHODOLOGIES --- p.15 / Chapter 3.1. --- RSSI RANGING --- p.15 / Chapter 3.1.1. --- Radio Fingerprint --- p.15 / Chapter 3.1.2. --- Radio Propagation Model --- p.17 / Chapter 3.1.3. --- Reference Tags --- p.18 / Chapter 3.1.4. --- Ordered Signal Strength Sequence --- p.19 / Chapter 3.2. --- UWB RANGING --- p.20 / Chapter 3.3. --- NEAR FIELD ELECTROMAGNETIC RANGING (NFER) --- p.21 / Chapter CHAPTER 4 --- CONVENTIONAL 360º REFLECTION-TYPE PHASE SHIFTER DESIGNS --- p.23 / Chapter 4.1. --- PARALLELING TWO SERIES-RESONANT VARACTOR CIRCUIT --- p.23 / Chapter 4.1.1. --- 360º Phase Shift --- p.24 / Chapter 4.1.2. --- Constant Insertion Loss --- p.24 / Chapter 4.1.3. --- Performance --- p.25 / Chapter 4.2. --- PARALLELING TWO ARMS HAVING 180O PHASE CHANGE WITH 90º OUT OF PHASE --- p.27 / Chapter 4.2.1. --- Linearity and 180º Phase Shift --- p.27 / Chapter 4.2.2. --- Constant Insertion Loss --- p.29 / Chapter 4.2.3. --- 360º Phase Shift --- p.29 / Chapter 4.2.4. --- Performance --- p.30 / Chapter 4.3. --- CONNECTING TWO ARMS HAVING 180O PHASE CHANGE WITH 90O OUT OF PHASE IN-SERIES --- p.31 / Chapter 4.3.1. --- Constant Insertion Loss --- p.31 / Chapter 4.3.2. --- 360º Phase Shift --- p.32 / Chapter 4.3.3. --- Performance --- p.32 / Chapter CHAPTER 5 --- AN ACTIVE RFID INDOOR POSITIONING SYSTEM UTILIZING ANALOG LINEAR PHASED ARRAY --- p.34 / Chapter 5.1. --- POSITIONING METHODOLOGY --- p.35 / Chapter 5.2. --- SYSTEM ARCHITECTURE --- p.37 / Chapter 5.2.1. --- Analog Linear Phased Array Antenna --- p.39 / Chapter 5.3. --- POSITIONING ALGORITHM --- p.51 / Chapter 5.3.1. --- Zone Decision --- p.51 / Chapter 5.3.2. --- Point Location --- p.52 / Chapter 5.4. --- EXPERIMENTAL RESULT --- p.58 / Chapter CHAPTER 6 --- NOVEL 360º REFLECTION-TYPE DIODE PHASE SHIFTER WITH CONSTANT INSERTION LOSS UNDER LOSSY SUBSTRATE --- p.65 / Chapter 6.1. --- REVIEW --- p.66 / Chapter 6.2. --- PROBLEMS --- p.68 / Chapter 6.3. --- PROPOSED SOLUTIONS --- p.71 / Chapter 6.3.1. --- Closed Reflection Coefficient Circle --- p.71 / Chapter 6.3.2. --- Centered Reflection Coefficient Circle --- p.74 / Chapter 6.4. --- SIMULATION AND MEASUREMENT RESULT --- p.77 / Chapter CHAPTER 7 --- CONCLUSION --- p.83 / REFERENCES --- p.85 / AUTHOR’S PUBLICATIONS --- p.88 / Chapter APPENDIX 1: --- DESIGN OF RFID TAG --- p.89 / Chapter APPENDIX 2: --- DESIGN OF RFID READER --- p.98 / Chapter APPENDIX 3: --- DESIGN OF RFID CONTROLLER --- p.100

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>