One of the fundamental assumptions made in the design of wireless networks is that the wireless devices have to be half-duplex, i.e., they cannot simultaneously transmit and receive in the same frequency band. The key deterrent in implementing a full-duplex wireless device, which can simultaneously transmit and receive in the same frequency band, is the large power differential between the self-interference from a device's own transmissions and the signal of interest coming from a distant source. In this thesis, we revisit this basic assumption and propose a full-duplex radio design. The design suppresses the self-interference signal by employing a combination of passive suppression, and active analog and digital cancellation mechanisms. The active cancellations are designed for wideband, multiple subcarrier (OFDM), and multiple antenna (MIMO) wireless communications systems. We then implement our design as a 20 MHz MIMO OFDM system with a 2.4 GHz center frequency, suitable for Wi-Fi systems. We perform extensive over-the-air tests to characterize our implementation. Our main contributions are the following: (a) the average amount of active cancellation increases as the received self-interference power increases and as a result, the rate of a full-duplex link increases as the transmit power of communicating devices increases, (b) applying digital cancellation after analog cancellation can sometimes increase the self-interference and the effectiveness of digital cancellation in a full-duplex system will depend on the performance of the cancellation stages that precede it, (c) our full-duplex device design achieves an average of 85 dB of self-interference cancellation over a 20 MHz bandwidth at 2.4 GHz, which is the best cancellation performance reported to date, (d) our full-duplex device design achieves 30-84% higher ergodic rates than its half-duplex counterpart for received powers in the range of [-75, -60] dBm. As a result, our design is the first one to achieve Wi-Fi ranges; in comparison, no implementation to date has achieved Wi-Fi ranges. Consequently, we have conclusively demonstrated that Wi-Fi full-duplex is practically feasible and hence shown that one of the commonly made assumptions in wireless networks is not fundamental.

In this thesis, we study a three-node full-duplex network, where the infrastructure node has simultaneous up- and downlink communication in the same frequency band with two half-duplex nodes. In addition to self-interference at the full-duplex infrastructure node, the three-node network has to contend with the inter-node interference between the two half-duplex nodes. The two forms of interferences differ in one important aspect that the self-interference is known at the interfered receiver. Therefore, we propose to leverage a wireless side-channel to manage the inter-node interference. We characterize the impact of inter-node interference on the network achievable rate region with and without a side-channel between the nodes. We present four distributed full-duplex inter-node interference cancellation schemes, which leverage the device-to-device wireless side-channel for improved interference cancellation. Of the four, bin-and-cancel is asymptotically optimal in high signal-to-noise ratio limit which uses Han-Kobayashi common-private message splitting and achieves within 1 bits/s/Hz of the capacity region for all values of channel parameters. The other three schemes are simpler compared to bin-and-cancel but achieve the near-optimal performance only in certain regimes of channel values. Asymptotic multiplexing gains of all proposed schemes are derived to show analytically that leveraging the side channel can be highly beneficial in increasing the multiplexing gain of the system exactly in those regimes where inter-node interference has the highest impact.

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The experimental work reported in this thesis quantified the productivity of lucerne over a two-year period (2000-2001) for a Mediterranean climate at Roseworthy in South Australia (34°32′S, 138°45′E), and determined associated dynamics for water and nitrogen in duplex soil. Shoot growth of dryland lucerne was limited primarily by the pattern and amount of incident rainfall, but high temperature (30-35oC) also constrained summer production. These high summer temperatures induced greater production when irrigation was applied, but under the normally dry summer conditions high temperatures combined with soil water deficit (up to 200mm) caused growth to cease. Thus, shoot dry matter yield under rainfed conditions was 4.9 t ha⁻¹ in 2000 (from 7 harvests) and 1.8 t ha⁻¹ in 2001 (from 5 harvests) whereas summer irrigation increased yield to 14.9 t ha⁻¹ in 2000 (7 harvests) and 7.1 t ha⁻¹ in 2001 (5 harvests). Under rainfed conditions the RUE was 0.55 g DM MJ⁻¹ PARi compared with 1.08 g DM MJ⁻¹ PARi in the irrigated treatment in 2000, reducing to 0.4 g DM MJ⁻¹ for the rainfed and 0.7 g DM MJ⁻¹ under limited irrigation in 2001. Lucerne plant population declined from 69 to 20 (plants m⁻²) in the rainfed treatment and the plants partially compensated for this in 2000 by increasing stem density from 300 to 400 m⁻² in 2000 although this declined back to 300 m⁻² in 2001. In all treatments more than 70% of root biomass was in the top 40 cm soil, this was partially due to the vertical distribution of plant available water but also to subsoil constraints to root development below 0.6m. Nevertheless, lucerne was able to extract water and nitrate to 1800 mm soil depth. Large amounts of irrigation >400mm) over summer (Dec 1999-Mar 2000) increased total soil water content, approaching the drained upper limit; causing a 600% increase in shoot dry matter yield, similarly higher growth rate (71 kg DM d⁻¹) and higher RUE (~1.7 g DM MJ⁻¹ ), confirming that water availability was the main constraint to lucerne growth. Delayed benefits of summer irrigation, especially in the subsurface treatment, were also observed later (July to October) when lucerne was able to scavenge excess irrigation water and nitrate stored in the 600-1800 mm soil profile, which resulted in increased shoot growth. Drainage below the effective rooting depth was negligible, even under irrigation, confirming that lucerne can dry soil profiles and reduce deep drainage. Average annual water use efficiency was 9 kg DM ha⁻¹ mm⁻¹ under rainfed conditions compared to ~15 kg DM ha⁻¹ mm⁻¹ under irrigated conditions. Shoot dry mattter production was closely related to evapotranspiration in all treatments, however, under rainfed conditions losses from evaporation were proportionally higher compared to irrigated treatments. Sub-surface drip irrigation proved superior to surface irrigation using 22% less water compared to surface sprinkler irrigation treatment with comparable yields. Biological N₂fixation was strongly related to shoot production with 18 to 27 kg N fixed per tonne of shoot dry matter across all seasons and treatments. Dependence on N₂fixation appeared to be unrelated to soil mineral N concentration and amounts of nitrate in the profile (to 1m) were generally quite low <35 kg N ha⁻¹). Soil water dynamics under both rainfed and surface irrigated treatments were adequately simulated by the Agricultural Production System Simulator (APSIM) with RMSD < 10% of the observed means and R² > 0.80 for the total soil profile (0-2000 mm). Simulation of growth and development was less satisfactory. For example, the RMSD was ~50% of observed mean for shoot biomass (R² = 0.68) in the rainfed treatment, and 36% (R² = 0.77) in the irrigated treatment. Overall, simulation of shoot DM production was close to observed values during the growing season (Apr-Nov), however the model was unable to capture the observed shoot yield in response to summer irrigation, with simulated shoot DM 40% less than the observed value in 2000 and 35% less in 2001. N dynamics were poorly simulated under these soil and climate conditions. Amounts of soil mineral nitrogen (kg NO⁻₃-N ha⁻¹) were adequately simulated in rainfed conditions but consistently over-predicted under irrigated conditions. This evaluation of APSIM highlights both good and poor model performance and the analysis indicates the need for caution when applying the model in situations where observed data is scarce. Areas requiring improvements to the model are identified. Overall this research has improved understanding of the limitations to potential production of lucerne in a Mediterranean environment on duplex soils and shown that APSIM-Lucerne can be used confidently for many applications, particularly soil-water dynamics. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1352515 / Thesis (Ph.D.) - University of Adelaide, School of Earth and Environmental Sciences, 2009

The experimental work reported in this thesis quantified the productivity of lucerne over a two-year period (2000-2001) for a Mediterranean climate at Roseworthy in South Australia (34°32′S, 138°45′E), and determined associated dynamics for water and nitrogen in duplex soil. Shoot growth of dryland lucerne was limited primarily by the pattern and amount of incident rainfall, but high temperature (30-35oC) also constrained summer production. These high summer temperatures induced greater production when irrigation was applied, but under the normally dry summer conditions high temperatures combined with soil water deficit (up to 200mm) caused growth to cease. Thus, shoot dry matter yield under rainfed conditions was 4.9 t ha⁻¹ in 2000 (from 7 harvests) and 1.8 t ha⁻¹ in 2001 (from 5 harvests) whereas summer irrigation increased yield to 14.9 t ha⁻¹ in 2000 (7 harvests) and 7.1 t ha⁻¹ in 2001 (5 harvests). Under rainfed conditions the RUE was 0.55 g DM MJ⁻¹ PARi compared with 1.08 g DM MJ⁻¹ PARi in the irrigated treatment in 2000, reducing to 0.4 g DM MJ⁻¹ for the rainfed and 0.7 g DM MJ⁻¹ under limited irrigation in 2001. Lucerne plant population declined from 69 to 20 (plants m⁻²) in the rainfed treatment and the plants partially compensated for this in 2000 by increasing stem density from 300 to 400 m⁻² in 2000 although this declined back to 300 m⁻² in 2001. In all treatments more than 70% of root biomass was in the top 40 cm soil, this was partially due to the vertical distribution of plant available water but also to subsoil constraints to root development below 0.6m. Nevertheless, lucerne was able to extract water and nitrate to 1800 mm soil depth. Large amounts of irrigation >400mm) over summer (Dec 1999-Mar 2000) increased total soil water content, approaching the drained upper limit; causing a 600% increase in shoot dry matter yield, similarly higher growth rate (71 kg DM d⁻¹) and higher RUE (~1.7 g DM MJ⁻¹ ), confirming that water availability was the main constraint to lucerne growth. Delayed benefits of summer irrigation, especially in the subsurface treatment, were also observed later (July to October) when lucerne was able to scavenge excess irrigation water and nitrate stored in the 600-1800 mm soil profile, which resulted in increased shoot growth. Drainage below the effective rooting depth was negligible, even under irrigation, confirming that lucerne can dry soil profiles and reduce deep drainage. Average annual water use efficiency was 9 kg DM ha⁻¹ mm⁻¹ under rainfed conditions compared to ~15 kg DM ha⁻¹ mm⁻¹ under irrigated conditions. Shoot dry mattter production was closely related to evapotranspiration in all treatments, however, under rainfed conditions losses from evaporation were proportionally higher compared to irrigated treatments. Sub-surface drip irrigation proved superior to surface irrigation using 22% less water compared to surface sprinkler irrigation treatment with comparable yields. Biological N₂fixation was strongly related to shoot production with 18 to 27 kg N fixed per tonne of shoot dry matter across all seasons and treatments. Dependence on N₂fixation appeared to be unrelated to soil mineral N concentration and amounts of nitrate in the profile (to 1m) were generally quite low <35 kg N ha⁻¹). Soil water dynamics under both rainfed and surface irrigated treatments were adequately simulated by the Agricultural Production System Simulator (APSIM) with RMSD < 10% of the observed means and R² > 0.80 for the total soil profile (0-2000 mm). Simulation of growth and development was less satisfactory. For example, the RMSD was ~50% of observed mean for shoot biomass (R² = 0.68) in the rainfed treatment, and 36% (R² = 0.77) in the irrigated treatment. Overall, simulation of shoot DM production was close to observed values during the growing season (Apr-Nov), however the model was unable to capture the observed shoot yield in response to summer irrigation, with simulated shoot DM 40% less than the observed value in 2000 and 35% less in 2001. N dynamics were poorly simulated under these soil and climate conditions. Amounts of soil mineral nitrogen (kg NO⁻₃-N ha⁻¹) were adequately simulated in rainfed conditions but consistently over-predicted under irrigated conditions. This evaluation of APSIM highlights both good and poor model performance and the analysis indicates the need for caution when applying the model in situations where observed data is scarce. Areas requiring improvements to the model are identified. Overall this research has improved understanding of the limitations to potential production of lucerne in a Mediterranean environment on duplex soils and shown that APSIM-Lucerne can be used confidently for many applications, particularly soil-water dynamics. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1352515 / Thesis (Ph.D.) - University of Adelaide, School of Earth and Environmental Sciences, 2009

Proefschrift Universiteit Maastricht. / Met lit. opg. en een samenvatting in het Nederlands.

Resumo: A trombose venosa profunda (TVP) dos membros inferiores é doença grave, potencialmente fatal e pode levar à síndrome pós-trombótica (SPT). A SPT é doença crônica, com consideráveis conseqüências socioeconômicas para os pacientes serviços de saúde. Sua fisiopatologia relaciona-se com o surgimento de hipertensão venosa, que ocorre devido à incompetência valvular e a obstrução da veia pelo trombo residual. Assim, é importante conhecer o processo de recanalização das veias trombosadas para melhor compreensão das seqüelas da TVP. Avaliar e quantificar o processo inicial de recanalização das veias dos membros inferiores após um episódio de TVP aguda pelo mapeamento dúplex em cores (MDC). Estudou-se pelo MDC 12 pacientes na fase aguda (até 10 dias), no 1°, 3º e 6º mês após o episódio agudo de TVP. Os pacientes foram mantidos com terapia anticoagulante adequada por 6 meses e orientados a usar meias de compressão elástica. Para avaliar e quantificar a recanalização foram utilizados o escore trombótico (ET) e a variação percentual do diâmetro venoso na máxima compressibilidade em relação a sua ausência (Δ%Øvmax/Øvsem). O ET foi verificado em 18 segmentos venosos (veias ilíaca externa; femoral comum; femoral profunda; femoral ao nível da junção e a 10 cm da prega inguinal; poplítea supra patelar e cavo; fibulares; tibiais posteriores; gastrocnêmias; soleares; veia safena magna ao nível da crossa, terço proximal, médio e distal; veia safena parva ao nível da crossa, terço proximal e médio). Segmentos venosos patentes tiveram ET de zero. A TVP foi considerada parcialmente oclusiva quando o segmento venoso foi não compressível com um sinal Doppler presente (ET = 1). Considerou-se a TVP totalmente oclusiva quando o segmento venoso foi não compressível e o sinal Doppler não foi encontrado (ET = 2). Para cada membro foi calculado o ET total... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The deep vein thrombosis (DVT) of the lower limbs is a serious, potentially fatal disease and it can lead to the post-thrombotic syndrome (PTS). The PTS is a chronic disease, with considerable social and economical consequences for the patients and health services. His physiopathology is connected with the appearance of vein high blood pressure that takes place due to the valval incompetence and the obstruction of the vein for the residual thrombus. So, it is important to know the process of recanalization of the thrombosed veins for better understanding of the sequels of the DVT. The objective of this study was to evaluate and quantify the early recanalization of the vein of the lower limbs after acute DVT by duplex ultrasound scanning (DUS). Twelve elegible patients were examined by DUS at acute phase (less than 10 days), 1°, 3º and 6º months after the first episode of DVT. All patients were treated initially with unfractionated heparin or low-molecular-weightheparin followed by oral anticoagulation for 6 months and strongly encouraged to use compression stockings. To evaluate and quantify the recanalization of the veins were used the thrombus escore (TS) and the percentage variation of the vein diameter during the maximal compressibility regarding his absence (PVVDMA). The thrombus score (TS) assigned to 18 vein segments: external iliac vein; common femoral vein; deep femoral vein; confluence of femoral and deep femoral vein; femoral vein 10 cm at the inguinal ligament; popliteal vein suprapatellar; popliteal vein fossa; fibular veins; posterior tibial veins; gastrocnemius veins; soleal veins; sapheno-femoral junction; grate saphenous... (Complete abstract click electronic access below) / Orientador: Hamilton Almeida Rollo / Coorientador: Marcone Lima Sobreira / Banca: José Bitu Moreno / Banca: Regina Moura / Mestre

In this thesis, spectrum sensing techniques are investigated for cognitive radio (CR) networks in order to improve the sensing and transmission performance of secondary networks. Specifically, the detailed exploration comprises of three areas, including single-node spectrum sensing based on eigenvalue-based detection, cooperative spectrum sensing under random secondary networks and full-duplex (FD) spectrum sensing and sharing techniques. In the first technical chapter of this thesis, eigenvalue-based spectrum sensing techniques, including maximum eigenvalue detection (MED), maximum minimum eigenvalue (MME) detection, energy with minimum eigenvalue (EME) detection and the generalized likelihood ratio test (GLRT) eigenvalue detector, are investigated in terms of total error rates and achievable throughput. Firstly, in order to consider the benefits of primary users (PUs) and secondary users (SUs) simultaneously, the optimal decision thresholds are investigated to minimize the total error rate, i.e. the summation of missed detection and false alarm rate. Secondly, the sensing-throughput trade-off is studied based on the GLRT detector and the optimal sensing time is obtained for maximizing the achievable throughput of secondary communications when the target probability of detection is achieved. In the second technical chapter, the centralized GLRT-based cooperative sensing technique is evaluated by utilizing a homogeneous Poisson point process (PPP). Firstly, since collaborating all the available SUs does not always achieve the best sensing performance under a random secondary network, the optimal number of cooperating SUs is investigated to minimize the total error rate of the final decision. Secondly, the achievable ergodic capacity and throughput of SUs are studied and the technique of determining an appropriate number of cooperating SUs is proposed to optimize the secondary transmission performance based on a target total error rate requirement. In the last technical chapter, FD spectrum sensing (FDSS) and sensing-based spectrum sharing (FD-SBSS) are investigated. There exists a threshold pair, not a single threshold, due to the self-interference caused by the simultaneous sensing and transmission. Firstly, by utilizing the derived expressions of false alarm and detection rates, the optimal decision threshold pair is obtained to minimize total error rate for the FDSS scheme. Secondly, in order to further improve the secondary transmission performance, the FD-SBSS scheme is proposed and the collision and spectrum waste probabilities are studied. Furthermore, different antenna partitioning methods are proposed to maximize the achievable throughput of SUs under both FDSS and FD-SBSS schemes.

Os aços inoxidáveis duplex são materiais altamente utilizados em diversos setores da indústria, e em componentes de alta responsabilidade, como por exemplo, tubulações na indústria de óleo e gás. Por este motivo, o conhecimento do material quanto às fases presentes, suas características mecânicas e seu comportamento em meio corrosivo é de grande importância. Devido ao tempo de uso e temperatura de exposição, o material pode sofrer danos, em decorrência da precipitação de fases intermetálicas, que fragilizam o material, causando perda de suas propriedades. Sendo assim, neste trabalho o aço UNS S 31803 foi analisado como recebido (laminado e solubilizado), e após a precipitação de fases intermetálicas. Para isso, amostras foram tratadas termicamente a 780°C, por diversos tempos, para promover diferentes quantidades de fases intermetálicas em cada amostra. Foram realizadas metalografia, análise em Microscopia Eletrônica de Varredura (EDS e EBSD) e Microscopia de Transmissão. Como técnica de caracterização das fases presentes, foi utilizada a Difração de Raios-X. Com relação às propriedades mecânicas, foi realizado ensaio de tração com as diversas amostras, a fim de analisar o limite de escoamento, limite de resistência e módulo elástico em cada condição de tratamento térmico. Foi realizado ensaio Charpy, obtendo-se os valores de energia absorvida pelo material ao sofrer impacto. O equipamento de ensaio de impacto utilizado é instrumentado e, com isso, valores de KId do material também foram obtidos, demonstrando que na presença das fases intermetálicas ocorre uma grande queda no valor da energia absorvida ao impacto pelo material. O material foi analisado em meio corrosivo contendo 3,5% NaCl, simulando o ambiente marinho, avaliando o comportamento do material nestas condições quando estão presentes as fases intermetálicas. Os resultados mostraram que as fases intermetálicas causam danos nas propriedades mecânicas do material, especialmente na resistência ao impacto, além de causar grande perda na resistência à corrosão do material quando exposto ao meio contendo cloreto (NaCl 3,5%). Além disso, é possível verificar diferentes variações na velocidade sônica do material, conforme a quantidade de fases intermetálicas presentes e a textura apresentada pelo material, sendo o ultrassom uma técnica sensível a esta variação microestrutural. / The duplex stainless steel is a material highly utilized in various industry sectors, in high responsibility components, for example, pipes in the oil and gas industry. For this reason, knowing the material microstructure, their mechanical properties and their behavior in corrosive environment is of great importance. Due to run time and exposure temperature, the material can be damaged as a result of the precipitation of intermetallic phases which weaken the material, causing loss of its properties. Thus, this work has analyzed the UNS S 31803 steel as received (laminate and solubilized) and after the precipitation of intermetallic phases. For this purpose, samples have been heated treated at 780 ° C during different to promote different amounts of intermetallic phases in each sample. Metallography, Scanning Electron Microscopy (EDS and EBSD) and Transmission Electronic Microscopy analysis have been performed. X-ray diffraction has been used as the characterization technique of present phases. With respect to mechanical properties, tensile testing was carried out in order to analyze the yield strength, tensile strength and elastic modulus in each condition of heat treatment. Charpy testing was performed, obtaining the values of absorbed energy by the material during the impact test. The impact tests were carried out in an instrumented equipment, so that KId values of the material were also obtained, demonstrating that there is a big drop in the absorbed energy by the material in the presence of intermetallic phases. The material was analyzed in a corrosive environment containing 3.5% NaCl, in order to simulate the marine conditions by evaluating the material behavior under these circumstances when intermetallic phases are present. The results demonstrate that the intermetallic phases cause decrease of the mechanical properties, especially in impact toughness, and causes loss in corrosion resistance of the material when exposed to environment containing chloride (NaCl 3.5%). Furthermore, it is possible to notice different variations in the sonic velocity of the material according to the amount of intermetallic phases and the texture presented by the material, so that the ultrasound is a sensitive technique to this microstructural variation.