Interaction between wave and coastal structure: Validation of two lagrangian numerical models with experimental results marine 2011

Numerical modeling of the interaction among waves and coastal structures is a challenge due to the many nonlinear phenomena involved, such as, wave propagation, wave transformation with water depth, interaction among incident and reflected waves, run-up / run-down and wave overtopping. Numerical models based on Lagrangian formulation, like SPH (Smoothed Particle Hydrodynamics), allow simulating complex free surface flows. The validation of these numerical models is essential, but comparing numerical results with experimental data is not an easy task. In the present paper, two SPH numerical models, SPHysics LNEC and SPH UNESP, are validated comparing the numerical results of waves interacting with a vertical breakwater, with data obtained in physical model tests made in one of the LNEC's flume. To achieve this validation, the experimental set-up is determined to be compatible with the Characteristics of the numerical models. Therefore, the flume dimensions are exactly the same for numerical and physical model and incident wave characteristics are identical, which allows determining the accuracy of the numerical models, particularly regarding two complex phenomena: wave-breaking and impact loads on the breakwater. It is shown that partial renormalization, i.e. renormalization applied only for particles near the structure, seems to be a promising compromise and an original method that allows simultaneously propagating waves, without diffusion, and modeling accurately the pressure field near the structure.

Optimal reactive power dispatch using stochastic chance-constrained programming

Deterministic Optimal Reactive Power Dispatch problem has been extensively studied, such that the demand power and the availability of shunt reactive power compensators are known and fixed. Give this background, a two-stage stochastic optimization model is first formulated under the presumption that the load demand can be modeled as specified random parameters. A second stochastic chance-constrained model is presented considering uncertainty on the demand and the equivalent availability of shunt reactive power compensators. Simulations on six-bus and 30-bus test systems are used to illustrate the validity and essential features of the proposed models. This simulations shows that the proposed models can prevent to the power system operator about of the deficit of reactive power in the power system and suggest that shunt reactive sourses must be dispatched against the unavailability of any reactive source. © 2012 IEEE.

Experimental comparative study on vortex-induced motion (VIM) of a monocolumn platform

An analysis methodology is presented as well as a comparison of results obtained from vortex-induced motion (VIM) model tests of the MonoGoM platform, a monocolumn floating unit designed for the Gulf of Mexico. The choice of scale between the model and the platform in which the tests took place was a very important issue that took into account the basin dimensions and mooring design. The tests were performed in three different basins: the IPT Towing Tank in Brazil (Sept. 2005), the NMRI Model Ship Experimental Towing Tank in Japan (Mar. 2007), and the NMRI Experimental Tank in Japan (Jun. 2008). The purpose is to discuss the most relevant issues regarding the concept, execution, and procedures to comparatively analyze the results obtained from VIM model tests, such as characteristic motion amplitudes, motion periods, and forces. The results pointed out the importance of considering the 2DOF in the model tests, i.e., the coexistence of the motions in both in-line and transverse directions. The approach employed in the tests was designed to build a reliable data set for comparison with theoretical and numerical models for VIM prediction, especially that of monocolumn platforms. [DOI: 10.1115/1.4003494]

An Overview of Relevant Aspects on VIM of Spar and Monocolumn Platforms

Vortex-induced motions (VIM) of floating structures are very relevant for the design of mooring and riser systems. In the design phase, spar and monocolumn VIM behavior, as well as semisubmersible and tension leg platform flow-induced motions, is studied and evaluated. This paper provides a checklist of topics and evidence from a number of sources to justify the selection that should be considered when designing spars or monocolumn platforms regarding the VIM phenomenon. An overview of the influential aspects of the VIM is presented such as heading, external appendages of the hull, concomitant presence of waves and currents, motion suppressor, draft condition (immersed portion of the hull), and external damping due to the presence of risers. Previous works concerning the VIM studies on spar and monocolumn platforms are also addressed. Whenever possible, the results of experiments from diverse authors on this matter are presented and compared. [DOI: 10.1115/1.4003698]

Estado nutricional e consumo alimentar de pacientes com psoríase dos tipos sistêmica e artropática sistêmica associada

OBJECTIVE: To identify the nutritional status and food intake of individuals with systemic psoriasis and psoriatic arthritis associated. METHODS: This is an exploratory and cross-sectional study with 34 men aged between 19 and 60 years seen at a Psoriasis Center. Participants were divided into systemic psoriasis group and arthritic-systemic psoriasis associated group. For nutritional assessment we used anthropometry, bioelectrical impedance analysis and whole-body plethysmography. Clinical and nutritional information were assessed using the clinical and nutritional history-taking, and the 24-hour dietary recall. For statistics the general linear model test (p < 0.05) was used. RESULTS: According to the body mass index 29.4% patients (n = 10) were eutrophic, 41.2% (n = 14) overweight and 29% (n = 10) obese. Almost all individuals (60%; n = 21) had body fat percentage above normal levels (> 25%) and a high risk for metabolic complications according to the waist circumference and the obesity index, however, there were no statistically significant differences between groups. The mean food intake, total fat, calories and protein were above recommended levels, being 58.8% for lipids (319.17 ± 241.02 mg of cholesterol and 17.42 ± 11.4 g saturated fatty acids); 29.4% for calories and 67.6% for proteins. Thus, regardless of the psoriasis type, an excessive consumption of calories, lipids, fatty acids, cholesterol and a higher incidence of overweight were found. CONCLUSION: The sample showed an abnormal nutritional condition, an increased risk for chronic diseases related to obesity, worsening of the psoriatic lesions, and poor quality of life.

IS THE U.S. SHALE GAS BOOM HAVING AN EFFECT ON THE EUROPEAN GAS MARKET?

This thesis focuses on the impact of the American shale gas boom on the European natural gas market. The study presents different tests in order to analyze the dynamics of natural gas prices in the U.S., U.K. and German natural gas market. The question of cointegration between these different markets are analyzed using several tests. More specifically, the ADF tests for the presence of a unit root. The error correction model test and the Johansen cointegration procedure are applied in order to accept or reject the hypothesis of an integrated market. The results suggest no evidence of cointegration between these markets. There currently is no evidence of an impact of the U.S. shale gas boom on the European market.

Selected topics in the Hydrodynamics of floating offshore wind turbines: heave damping and second order surge motions

La Energía eléctrica producida mediante tecnología eólica flotante es uno de los recursos más prometedores para reducir la dependencia de energía proveniente de combustibles fósiles. Esta tecnología es de especial interés en países como España, donde la plataforma continental es estrecha y existen pocas áreas para el desarrollo de estructuras fijas. Entre los diferentes conceptos flotantes, esta tesis se ha ocupado de la tipología semisumergible. Estas plataformas pueden experimentar movimientos resonantes en largada y arfada. En largada, dado que el periodo de resonancia es largo estos puede ser inducidos por efectos de segundo orden de deriva lenta que pueden tener una influencia muy significativa en las cargas en los fondeos. En arfada las fuerzas de primer orden pueden inducir grandes movimientos y por tanto la correcta determinación del amortiguamiento es esencial para la analizar la operatividad de la plataforma. Esta tesis ha investigado estos dos efectos, para ello se ha usado como caso base el diseño de una plataforma desarrollada en el proyecto Europeo Hiprwind. La plataforma se compone de 3 columnas cilíndricas unidas mediante montantes estructurales horizontales y diagonales, Los cilindros proporcionan flotabilidad y momentos adrizante. A la base de cada columna se le ha añadido un gran “Heave Plate” o placa de cierre. El diseño es similar a otros diseños previos (Windfloat). Se ha fabricado un modelo a escala de una de las columnas para el estudio detallado del amortiguamiento mediante oscilaciones forzadas. Las dimensiones del modelo (1m diámetro en la placa de cierre) lo hacen, de los conocidos por el candidato, el mayor para el que se han publicado datos. El diseño del cilindro se ha realizado de tal manera que permite la fijación de placas de cierre planas o con refuerzo, ambos modelos se han fabricado y analizado. El modelo con refuerzos es una reproducción exacta del diseño a escala real incluyendo detalles distintivos del mismo, siendo el más importante la placa vertical perimetral. Los ensayos de oscilaciones forzadas se han realizado para un rango de frecuencias, tanto para el disco plano como el reforzado. Se han medido las fuerzas durante los ensayos y se han calculado los coeficientes de amortiguamiento y de masa añadida. Estos coeficientes son necesarios para el cálculo del fondeo mediante simulaciones en el dominio del tiempo. Los coeficientes calculados se han comparado con la literatura existente, con cálculos potenciales y por ultimo con cálculos CFD. Para disponer de información relevante para el diseño estructural de la plataforma se han medido y analizado experimentalmente las presiones en la parte superior e inferior de cada placa de cierre. Para la correcta estimación numérica de las fuerzas de deriva lenta en la plataforma se ha realizado una campaña experimental que incluye ensayos con modelo cautivo de la plataforma completa en olas bicromaticas. Pese a que estos experimentos no reproducen un escenario de oleaje realista, los mismos permiten una verificación del modelo numérico mediante la comparación de fuerzas medidas en el modelo físico y el numérico. Como resultados de esta tesis podemos enumerar las siguientes conclusiones. 1. El amortiguamiento y la masa añadida muestran una pequeña dependencia con la frecuencia pero una gran dependencia con la amplitud del movimiento. siendo coherente con investigaciones existentes. 2. Las medidas con la placa de cierre reforzada con cierre vertical en el borde, muestra un amortiguamiento significativamente menor comparada con la placa plana. Esto implica que para ensayos de canal es necesario incluir estos detalles en el modelo. 3. La masa añadida no muestra grandes variaciones comparando placa plana y placa con refuerzos. 4. Un coeficiente de amortiguamiento del 6% del crítico se puede considerar conservador para el cálculo en el dominio de la frecuencia. Este amortiguamiento es equivalente a un coeficiente de “drag” de 4 en elementos de Morison cuadráticos en las placas de cierre usadas en simulaciones en el dominio del tiempo. 5. Se han encontrado discrepancias en algunos valores de masa añadida y amortiguamiento de la placa plana al comparar con datos publicados. Se han propuesto algunas explicaciones basadas en las diferencias en la relación de espesores, en la distancia a la superficie libre y también relacionadas con efectos de escala. 6. La presión en la placa con refuerzos son similares a las de la placa plana, excepto en la zona del borde donde la placa con refuerzo vertical induce una gran diferencias de presiones entre la cara superior e inferior. 7. La máxima diferencia de presión escala coherentemente con la fuerza equivalente a la aceleración de la masa añadida distribuida sobre la placa. 8. Las masas añadidas calculadas con el código potencial (WADAM) no son suficientemente precisas, Este software no contempla el modelado de placas de pequeño espesor con dipolos, la poca precisión de los resultados aumenta la importancia de este tipo de elementos al realizar simulaciones con códigos potenciales para este tipo de plataformas que incluyen elementos de poco espesor. 9. Respecto al código CFD (Ansys CFX) la precisión de los cálculos es razonable para la placa plana, esta precisión disminuye para la placa con refuerzo vertical en el borde, como era de esperar dado la mayor complejidad del flujo. 10. Respecto al segundo orden, los resultados, en general, muestran que, aunque la tendencia en las fuerzas de segundo orden se captura bien con los códigos numéricos, se observan algunas reducciones en comparación con los datos experimentales. Las diferencias entre simulaciones y datos experimentales son mayores al usar la aproximación de Newman, que usa únicamente resultados de primer orden para el cálculo de las fuerzas de deriva media. 11. Es importante remarcar que las tendencias observadas en los resultados con modelo fijo cambiarn cuando el modelo este libre, el impacto que los errores en las estimaciones de fuerzas segundo orden tienen en el sistema de fondeo dependen de las condiciones ambientales que imponen las cargas ultimas en dichas líneas. En cualquier caso los resultados que se han obtenido en esta investigación confirman que es necesaria y deseable una detallada investigación de los métodos usados en la estimación de las fuerzas no lineales en las turbinas flotantes para que pueda servir de guía en futuros diseños de estos sistemas. Finalmente, el candidato espera que esta investigación pueda beneficiar a la industria eólica offshore en mejorar el diseño hidrodinámico del concepto semisumergible. ABSTRACT Electrical power obtained from floating offshore wind turbines is one of the promising resources which can reduce the fossil fuel energy consumption and cover worldwide energy demands. The concept is the most competitive in countries, such as Spain, where the continental shelf is narrow and does not provide space for fixed structures. Among the different floating structures concepts, this thesis has dealt with the semisubmersible one. Platforms of this kind may experience resonant motions both in surge and heave directions. In surge, since the platform natural period is long, such resonance can be excited with second order slow drift forces and may have substantial influence on mooring loads. In heave, first order forces can induce significant motion, whose damping is a crucial factor for the platform downtime. These two topics have been investigated in this thesis. To this aim, a design developed during HiPRWind EU project, has been selected as reference case study. The platform is composed of three cylindrical legs, linked together by a set of structural braces. The cylinders provide buoyancy and restoring forces and moments. Large circular heave plates have been attached to their bases. The design is similar to other documented in literature (e.g. Windfloat), which implies outcomes could have a general value. A large scale model of one of the legs has been built in order to study heave damping through forced oscillations. The final dimensions of the specimen (one meter diameter discs) make it, to the candidate’s knowledge, the largest for which data has been published. The model design allows for the fitting of either a plain solid heave plate or a flapped reinforced one; both have been built. The latter is a model scale reproduction of the prototype heave plate and includes some distinctive features, the most important being the inclusion of a vertical flap on its perimeter. The forced oscillation tests have been conducted for a range of frequencies and amplitudes, with both the solid plain model and the vertical flap one. Forces have been measured, from which added mass and damping coefficients have been obtained. These are necessary to accurately compute time-domain simulations of mooring design. The coefficients have been compared with literature, and potential flow and CFD predictions. In order to provide information for the structural design of the platform, pressure measurements on the top and bottom side of the heave discs have been recorded and pressure differences analyzed. In addition, in order to conduct a detailed investigation on the numerical estimations of the slow-drift forces of the HiPRWind platform, an experimental campaign involving captive (fixed) model tests of a model of the whole platform in bichromatic waves has been carried out. Although not reproducing the more realistic scenario, these tests allowed a preliminary verification of the numerical model based directly on the forces measured on the structure. The following outcomes can be enumerated: 1. Damping and added mass coefficients show, on one hand, a small dependence with frequency and, on the other hand, a large dependence with the motion amplitude, which is coherent with previously published research. 2. Measurements with the prototype plate, equipped with the vertical flap, show that damping drops significantly when comparing this to the plain one. This implies that, for tank tests of the whole floater and turbine, the prototype plate, equipped with the flap, should be incorporated to the model. 3. Added mass values do not suffer large alterations when comparing the plain plate and the one equipped with a vertical flap. 4. A conservative damping coefficient equal to 6% of the critical damping can be considered adequate for the prototype heave plate for frequency domain analysis. A corresponding drag coefficient equal to 4.0 can be used in time domain simulations to define Morison elements. 5. When comparing to published data, some discrepancies in added mass and damping coefficients for the solid plain plate have been found. Explanations have been suggested, focusing mainly on differences in thickness ratio and distance to the free surface, and eventual scale effects. 6. Pressures on the plate equipped with the vertical flap are similar in magnitude to those of the plain plate, even though substantial differences are present close to the edge, where the flap induces a larger pressure difference in the reinforced case. 7. The maximum pressure difference scales coherently with the force equivalent to the acceleration of the added mass, distributed over the disc surface. 8. Added mass coefficient values predicted with the potential solver (WADAM) are not accurate enough. The used solver does not contemplate modeling thin plates with doublets. The relatively low accuracy of the results highlights the importance of these elements when performing potential flow simulations of offshore platforms which include thin plates. 9. For the full CFD solver (Ansys CFX), the accuracy of the computations is found reasonable for the plain plate. Such accuracy diminishes for the disc equipped with a vertical flap, an expected result considering the greater complexity of the flow. 10. In regards to second order effects, in general, the results showed that, although the main trend in the behavior of the second-order forces is well captured by the numerical predictions, some under prediction of the experimental values is visible. The gap between experimental and numerical results is more pronounced when Newman’s approximation is considered, making use exclusively of the mean drift forces calculated in the first-order solution. 11. It should be observed that the trends observed in the fixed model test may change when the body is free to float, and the impact that eventual errors in the estimation of the second-order forces may have on the mooring system depends on the characteristics of the sea conditions that will ultimately impose the maximum loads on the mooring lines. Nevertheless, the preliminary results obtained in this research do confirm that a more detailed investigation of the methods adopted for the estimation of the nonlinear wave forces on the FOWT would be welcome and may provide some further guidance for the design of such systems. As a final remark, the candidate hopes this research can benefit the offshore wind industry in improving the hydrodynamic design of the semi-submersible concept.

Non prismatic folded roof structure

The design of a prestressed concrete roof is described. A special linear elastic analysis of non-prismatic folded structures has been applied. The obtained results have been compared to the results deducted from a small scale model test. Conclusions about the efficiency of these type of structures are shown.

Electromagnetic fields inside a lossy, multilayered spherical head phantom excited by MRI coils: models and methods

The precise evaluation of electromagnetic field (EMF) distributions inside biological samples is becoming an increasingly important design requirement for high field MRI systems. In evaluating the induced fields caused by magnetic field gradients and RF transmitter coils, a multilayered dielectric spherical head model is proposed to provide a better understanding of electromagnetic interactions when compared to a traditional homogeneous head phantom. This paper presents Debye potential (DP) and Dyadic Green's function (DGF)-based solutions of the EMFs inside a head-sized, stratified sphere with similar radial conductivity and permittivity profiles as a human head. The DP approach is formulated for the symmetric case in which the source is a circular loop carrying a harmonic-formed current over a wide frequency range. The DGF method is developed for generic cases in which the source may be any kind of RF coil whose current distribution can be evaluated using the method of moments. The calculated EMFs can then be used to deduce MRI imaging parameters. The proposed methods, while not representing the full complexity of a head model, offer advantages in rapid prototyping as the computation times are much lower than a full finite difference time domain calculation using a complex head model. Test examples demonstrate the capability of the proposed models/methods. It is anticipated that this model will be of particular value for high field MRI applications, especially the rapid evaluation of RF resonator (surface and volume coils) and high performance gradient set designs.

Numerical simulation for dynamic positioning in pack ice

This thesis investigates the numerical modelling of Dynamic Position (DP) in pack ice. A two-dimensional numerical model for ship-ice interaction was developed using the Discrete Element Method (DEM). A viscous-elastic ice rheology was adopted to model the dynamic behaviour of the ice floes. Both the ship-ice and the ice-ice contacts were considered in the interaction force. The environment forces and the hydrodynamic forces were calculated by empirical formulas. After the current position and external forces were calculated, a Proportional-Integral-Derivative (PID) control and thrust allocation algorithms were applied on the vessel to control its motion and heading. The numerical model was coded in Fortran 90 and validated by comparing computation results to published data. Validation work was first carried out for the ship-ice interaction calculation, and former researchers’ simulation and model test results were used for the comparison. With confidence in the interaction model, case studies were conducted to predict the DP capability of a sample Arctic DP vessel.

Centrifuge modeling of oblique pipe-soil interaction in dense and loose sand

Due to relative ground movement, buried pipelines experience geotechnical loads. The imposed geotechnical loads may initiate pipeline deformations that affect system serviceability and integrity. Engineering guidelines (e.g., ALA, 2005; Honegger and Nyman, 2001) provide the technical framework to develop idealized structural models to analyze pipe‒soil interaction events and assess pipe mechanical response. The soil behavior is modeled using discrete springs that represent the geotechnical loads per unit pipe length developed during the interaction event. Soil forces are defined along three orthogonal directions (i.e., axial, lateral and vertical) to analyze the response of pipelines. Nonlinear load-displacement relationships of soil defined by a spring, is independent of neighboring spring elements. However, recent experimental and numerical studies demonstrate significant coupling effects during oblique (i.e., not along one of the orthogonal axes) pipe‒soil interaction events. In the present study, physical modeling using a geotechnical centrifuge was conducted to improve the current understanding of soil load coupling effects of buried pipes in loose and dense sand. A section of pipeline, at shallow burial depth, was translated through the soil at different oblique angles in the axial-lateral plane. The force exerted by the soil on pipe is critically examined to assess the significance of load coupling effects and establish a yield envelope. The displacements required to soil yield force are also examined to assess potential coupling in mobilization distance. A set of laboratory tests were conducted on the sand used for centrifuge modeling to find the stress-strain behavior of sand, which was used to examine the possible mechanisms of centrifuge model test. The yield envelope, deformation patterns, and interpreted failure mechanisms obtained from centrifuge modeling are compared with other physical modeling and numerical simulations available in the literature.

Submarine slope failures in gassy soils

Submarine slope stability has become an important concern and a subject of research with increasing demand for offshore developments and technological advancement for harsh and challenging environments. The consequences of submarine slope failure adjacent to oil and gas facilities would have a large financial, safety and regulatory impact. This current research work investigates potential failure of submarine gassy slopes triggered by tidal variations. Due to tidal variations, failure of an unsaturated slope may occur under specific combinations of increasing degree of saturation and soil permeability, and decreasing tidal period. Novel physical model tests in a geotechnical centrifuge were undertaken to examine submarine slope failure mechanisms containing gassy sediments. The model preparation techniques, measurement systems and results are presented. The response observed in the model test is discussed and further developments proposed. The buried PPT’s response of the submarine slope are comparable in terms of attenuation and phase lag with Nagaswaran (1983) and with field measurements of Atigh and Byrne (2004) in terms of phase lag.

Assessment of primary energy conversions of oscillating water columns. II. Power take-off and validations

This is the second part of the assessment of primary energy conversions of oscillating water columns (OWCs) wave energy converters. In the first part of the research work, the hydrodynamic performance of OWC wave energy converter has been extensively examined, targeting on a reliable numerical assessment method. In this part of the research work, the application of the air turbine power take-off (PTO) to the OWC device leads to a coupled model of the hydrodynamics and thermodynamics of the OWC wave energy converters, in a manner that under the wave excitation, the varying air volume due to the internal water surface motion creates a reciprocating chamber pressure (alternative positive and negative chamber pressure), whilst the chamber pressure, in turn, modifies the motions of the device and the internal water surface. To do this, the thermodynamics of the air chamber is first examined and applied by including the air compressibility in the oscillating water columns for different types of the air turbine PTOs. The developed thermodynamics is then coupled with the hydrodynamics of the OWC wave energy converters. This proposed assessment method is then applied to two generic OWC wave energy converters (one bottom fixed and another floating), and the numerical results are compared to the experimental results. From the comparison to the model test data, it can be seen that this numerical method is capable of assessing the primary energy conversion for the oscillating water column wave energy converters.

An experimental investigation by towing tank on VIV of a long flexible cylinder for deepwater riser application

In this study, the dynamic response of a vertical flexible cylinder vibrating at low mode numbers with combined x-y motion was investigated in a towing tank. The uniform flow was simulated by towing the flexible cylinder along the tank in still water; therefore, the turbulence intensity of the free flow was negligible in obtaining more reliable results. A lower branch of dominant frequencies with micro vibration amplitude was found in both cross-flow and in-line directions. This justifiable discrepancy was likely caused by an initial lock-in. The maximum attainable amplitude, modal analysis and x-y trajectory in cross-flow and in-line directions are reported here and compared with previous literature, along with some good agreements and different observations that were obtained from the study. Drag and lift coefficients are also evaluated by making use of a generalized integral transform technique approach, yielding an alternative method to study fluid force acting upon a flexible cylinder.

The development of planar high-K/III-V p-channel MOSFETs for post-silicon CMOS

Conventional Si complementary-metal-oxide-semiconductor (CMOS) scaling is fast approaching its limits. The extension of the logic device roadmap for future enhancements in transistor performance requires non-Si materials and new device architectures. III-V materials, due to their superior electron transport properties, are well poised to replace Si as the channel material beyond the 10nm technology node to mitigate the performance loss of Si transistors from further reductions in supply voltage to minimise power dissipation in logic circuits. However several key challenges, including a high quality dielectric/III-V gate stack, a low-resistance source/drain (S/D) technology, heterointegration onto a Si platform and a viable III-V p-metal-oxide-semiconductor field-effect-transistor (MOSFET), need to be addressed before III-Vs can be employed in CMOS. This Thesis specifically addressed the development and demonstration of planar III-V p-MOSFETs, to complement the n-MOSFET, thereby enabling an all III-V CMOS technology to be realised. This work explored the application of InGaAs and InGaSb material systems as the channel, in conjunction with Al2O3/metal gate stacks, for p-MOSFET development based on the buried-channel flatband device architecture. The body of work undertaken comprised material development, process module development and integration into a robust fabrication flow for the demonstration of p-channel devices. The parameter space in the design of the device layer structure, based around the III-V channel/barrier material options of In_x≥0.53Ga_1-xAs/In_0.52Al_0.48As and In_x≥0.1Ga_1-xSb/AlSb, was systematically examined to improve hole channel transport. A mobility of 433 cm²/Vs, the highest room temperature hole mobility of any InGaAs quantum-well channel reported to date, was obtained for the In_0.85Ga_0.15As (2.1% strain) structure. S/D ohmic contacts were developed based on thermally annealed Au/Zn/Au metallisation and validated using transmission line model test structures. The effects of metallisation thickness, diffusion barriers and de-oxidation conditions were examined. Contacts to InGaSb-channel structures were found to be sensitive to de-oxidation conditions. A fabrication process, based on a lithographically-aligned double ohmic patterning approach, was realised for deep submicron gate-to-source/drain gap (L_side) scaling to minimise the access resistance, thereby mitigating the effects of parasitic S/D series resistance on transistor performance. The developed process yielded gaps as small as 20nm. For high-k integration on GaSb, ex-situ ammonium sulphide ((NH₄)₂S) treatments, in the range 1%-22%, for 10min at 295K were systematically explored for improving the electrical properties of the Al₂O₃/GaSb interface. Electrical and physical characterisation indicated the 1% treatment to be most effective with interface trap densities in the range of 4 - 10×10¹²cm^-2eV^-1 in the lower half of the bandgap. An extended study, comprising additional immersion times at each sulphide concentration, was further undertaken to determine the surface roughness and the etching nature of the treatments on GaSb. A number of p-MOSFETs based on III-V-channels with the most promising hole transport and integration of the developed process modules were successfully demonstrated in this work. Although the non-inverted InGaAs-channel devices showed good current modulation and switch-off characteristics, several aspects of performance were non-ideal; depletion-mode operation, modest drive current (I_d,sat=1.14mA/mm), double peaked transconductance (g_m=1.06mS/mm), high subthreshold swing (SS=301mV/dec) and high on-resistance (R_on=845kΩ.μm). Despite demonstrating substantial improvement in the on-state metrics of I_d,sat (11×), g_m (5.5×) and R_on (5.6×), inverted devices did not switch-off. Scaling gate-to-source/drain gap (L_side) from 1μm down to 70nm improved I_d,sat (72.4mA/mm) by a factor of 3.6 and gm (25.8mS/mm) by a factor of 4.1 in inverted InGaAs-channel devices. Well-controlled current modulation and good saturation behaviour was observed for InGaSb-channel devices. In the on-state In_0.3Ga_0.7Sb-channel (I_d,sat=49.4mA/mm, g_m=12.3mS/mm, R_on=31.7kΩ.μm) and In_0.4Ga_0.6Sb-channel (I_d,sat=38mA/mm, g_m=11.9mS/mm, R_on=73.5kΩ.μm) devices outperformed the InGaAs-channel devices. However the devices could not be switched off. These findings indicate that III-V p-MOSFETs based on InGaSb as opposed to InGaAs channels are more suited as the p-channel option for post-Si CMOS.