Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Long-chain hydrocarbons are of value to numerous lucrative industries. Due to the low volatility and close melting and boiling points of these solutes, traditional fractionation methods lack the required selectivity for separation and cause thermal degradation of the product. This project investigates the feasibility of Supercritical Fluid Extraction (SFE) for processing these systems, with the primary objective of modelling the high-pressure vapour-liquid equilibrium (VLE) properties of hydrocarbon solutes with a light-weight solvent using a semiempirical equation of state (EOS). Pure component vapour pressures and saturated liquid volumes are also investigated. A thorough investigation into the phase behaviour of the n-alkanes, 1-alcohols, carboxylic acids and esters in light weight supercritical solvents CO2, ethane and propane revealed that the solute structure and temperature largely influence the solute solubility and process feasibility. Good selectivity amongst the various solutes was observed for all three solvents, but very high pressures were required for complete miscibility using CO2 (exceeding 30 MPa). The quadrapole moment of CO2 further leads to complexities in phase behaviour such as temperature and density inversions (CO2/alkanes and CO2/alcohols) and 3-phase regions within the operating range. Simple linear trends in pressure vs. carbon number and temperature were observed for all the considered series using ethane and propane and these solvents were thus selected for conducting the modelling for this study. A thorough review of semi-emperical EOS models from literature revealed that the simple cubic equations of state (CEOSs) provide a promising modelling approach for SFE applications due to their simplicity, flexibility and reliability. The simple Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK) EOSs provide good correlation of vapour pressure (%AAD below 5 %) for all the series over a large carbon number range (up to nC20), provided a two parameter alpha function is used. A 3rd parameter in the volume dependence for Patel-Teja (PT) EOS provides considerable improvement over the PR and SRK EOSs for satureate liquid volume correlations of the non-polar solutes (alkanes and esters), but offers virtually no advantage for the more polar alcohols and acids. The CEOSs therefore suffer clear limitations in simultaneous representation of these saturation properties (vapour pressure and liquid molar volume) for the systems of interest. Good correlations of high pressure binary VLE data were obtained using CEOSs available in the Aspen Plus ® simulator (% AAD in P, T and X2 generally below 1 % and ranging from 4 to 12 % for Y2 for all series) provided that two binary interaction parameters (BIPs) are used in the model mixing rules, irrespective of the model used. Aspen Plus ® was further validated as a reliable thermodynamic tool by comparing model fits using the RK-ASPEN model with parameters obtained from the Aspen Plus ® data regression routine and computational methods used in self-developed MATLAB software. Very similar results were obtained for both computational methods, which encourages the use of Aspen Plus ® for process modelling in SFE applications. A statistical sensitivity analysis into the relative effect and interactions between 6 modelling factors in applying the CEOSs revealed that the mixing rules, temperature and solute structure had the largest effect on the correlation of the high pressure VLE, with the pure component limit having negligible effect once BIPs are fitted to data. A significant interaction was, however, observed between the pure component model and the solute structure and temperature, which suggest that accurate correlation of mixture VLE does not solely rely on appropriate mixing rule selection, but also the pure model. Binary interaction parameters (BIPs) in model mixing rules were found to become intercorrelated when more than one are used, greatly impeding the development of generalized correlations. BIPs were also found to be sensitive to the pure component limit (alpha function and pure constants used), the temperature, the combining rules used and possibly the fluid density. These factors should all be taken into account systematically for developing generalized correlations which therefore fell outside the scope of this study. Recommendations were, however, made on how the MATLAB software developed in this study can be used to both expand the size of the statistical analysis already conducted into relevant modelling factors and to develop new generalized correlations for BIPs and new mixing rules. / AFRIKAANSE OPSOMMING: Lang-ketting koolwaterstowwe is van waarde in talle winsgewende industriële toepassings. Vanweë die lae vlugbaarheiden ooreenstemmende kook- en smeltpunte van hierdie molekules, toon tradisionele fraktioneringsmetodes nie die nodige selektiwiteit vir ekstraksie nie en veroorsaak bonop termiese degradering van die produk. Hierdie projek ondersoek dus die lewensvatbaarheid van superkritiese ekstraksie vir die prosesering van hierdie sisteme, met primêre fokus op die modellering van die hoë-druk damp-vloeistof ewewig eienskappe van koolwaterstowwe opgelos in ‘n lae-massa oplosmiddel met gebruik van ‘n semi-empiriese toestandsvergelyking. Suiwer-komponent dampdrukke en versadigde vloeistof volumes word ook ondersoek. ‘n Deeglike ondersoek na die fasegedrag van die n-alkane, 1-alkohole, korboksiel-sure asook esters in lae-massa superkritiese oplosmidds CO2, etaan en propaan toon dat die struktuur van die opgeloste stof en die temperatuur ‘n groot invloed het op die oplosbaarheid en proses lewensvatbaarheid. Goeie selektiwiteit tussen die verskillende koolwaterstowwe was waargeneem vir al drie oplosmiddels, alhoewel baie hoë drukke nodig was vir totale vermenging van die fases in CO2 (hoër as 30 MPa). Die quadrupool moment van CO2 veroorsaak verder ongewenste kompleksiteite in fase gedrag soos temperatuuren digtheid inversies (CO2/alkane en CO2/alkohole) en 3-fase-gebiede in die bedryfs-kondisies. Eenvoudige lineêre tendense in druk tenoor die koolstofnommer van die opgeloste stof asook die temperatuur was waargeneem vir al die ondersoekte koolwaterstof reekse in etaan en propaan en hierdie oplosmiddels was dus gekies vir die modellering vir hierdie studie. 'n Deeglike oorsig van semi-empiriese toestandsvergelykings uit die literatuur het getoon dat die eenvoudige kubiese toestandsvergelykings ‘n belowende modelleringsbenadering bied vir superkritiese ekstraksie toepassings vanweë hul eenvoudigeid, buigsaamheid enbetroubaarheid. Die eenvoudige Peng-Robinson (PR) en Soave-Redlich-Kwong (SRK) toestandsvergelykings bied goeie korrelasie van suiwer dampdruk (foute laer as 5 %) vir alle koolwaterstowwe oor ‘n groot koolstofnommer gebied (tot by nC20), met die voorwaarde dat ‘n 2 parameter alpha funksie gebruik word. ‘n 3rde parameter in die volume afhanklikheid van die Patel-Teja (PT) toestandsvergelyking bied ‘n beduidende verbetering in die passing van die versadigde vloeistof volume vir die nie-polêre koolwaterstowwe (n-alkane en die esters), maar bied geen voordeel vir die meer polêre alkohole en karkoksiel sure nie. Die kubiese modelle toon dus duidelike beperkings vir die gelyktydige voorstelling van hierdie versadigingde eienskappe (dampdruk en vloeistof volume) vir die sisteme van belang. Goeie korrelasie van hoë druk binêre damp-vloeistof ewewig data was verkry deur gebruik van die kubiese toestandsvergelykings beskikbaar inAspen Plus ® (fout in P, T en X2 tipies laer as 1 % en van 4 tot 12 % vir Y2 vir alle sisteme), met die voorwaarde dat 2 binêre interaksie parameters gebuik word in die model mengreëls, onafhanklik van die model. Aspen Plus ® was verder bekraktig as ‘n betroubare termodinamiese hulpmiddel deur model passings te vergelyk met die RK-ASPEN model tussen gevalle waar parameters verkry is deur die beskikbare regressie metode in Aspen Plus ® en metodes gebruik in self-ontwikkelde MATLAB sagteware. Eenderse resultate was verkry vir beide berekeningsmetodes, wat die gebruik van Aspen Plus ® vir prosesmodellering in superkritiese ekstrasie toepassings aanmoedig. ‘n Satistiese sensitiwiteits analise op die relatiewe effek en interaksies tussen 6 modelleringsfaktore in die toepassing van die kubiese toestandsvergelykings het gevind dat die mengreëls, temperatuur en die stuktuur van die opgeloste stof die grootste effek op die korrelasie van hoë druk binêre damp-vloeistof ewewig het, met ‘n weglaatbare effek vandie suiwerkomponent limiet waargeneem sodra binêre interaksie parameters gepas is aan data. ‘n Beduidende interaksie was wel waargeneem tussen die suiwerkomponent model en die struktuur van die opgeloste stof asook die temperatuur, wat daarop dui dat akurate korrelasie van mengsel damp-vloeistof ewewig nie slegs afhanklink is van ‘n gepaste keuse van mengreëls nie, maar ook die suiwer-komponent model. Binêre interaksie parameters in die model mengreëls ondergaan inter-korrelasie wanneer meer as een interaksie parameter gebruik word, wat die ontwikkeling van algemeen toepaslike korrelasies grotendeels belemmer. Binêre interaksie parameters was ook bevind om sensitief te wees tot die suiwer component limiet (alpha funksie en suiwer konstantes wat gebruik is), die temperatuur, die kombineringsreëls en moontlik die vloeistof digtheid. Hierdie faktore moet dus almal sistematies in ag geneem word wanneer algemeen toepaslike korrelasies ontwikkel word, wat dus buite die omvang van die huidge studie val. Aanbevelings was wel gemaak vir hoe die MATLAB sagteware ontwikkel vir hierdie studie gebruik kan word om beide die betaande statistiese analise uit te brei, asook nuwe korrelasies vir binêre interaksies parameters en nuwe mengreëls te ontwikkel.

Le but du présent travail est la caractérisation des équilibres chimiques et des ELV pour les systèmes CO2/Diethanolamine(DEA)/H2O/MeOH et CO2 /Diethanolamine (DEA)/H2O/ PEG400.<br/> L'effet de composition du solvant physique sur l'absorption du CO2 a été étudié en utilisant quatre compositions (de 0% à 30% en masse d'alcool avec une composition fixe - 30% - de DEA), les mesures étant réalisées à une température de 298,15K et à divers taux de charge en CO2 (de 0 à 0,9).<br/> Les mesures expérimentales réalisées concernaient à la fois des données de solubilité et des donnée de spéciation. Ainsi, L'effet de composition de MeOH a été étudié en utilisant le dispositif expérimental original déjà utilisé pour l'analyse des systèmes Eau-DEA-CO2 (Sidi-Boumedine, 2003). Pour le système avec PEG 400, un nouvel dispositif expérimental permettant d'écarter la limitation de pression du précédent dispositif a été développé.<br/> La base de données originale obtenue comprenant des nouvelles données de solubilité et de composition de la phase liquide a permis la modélisation du système CO2/DEA/H2O/CH3OH en utilisant une équation d'état d'électrolyte développée au laboratoire (Fürst, 1993) représentant ainsi les propriétés d'équilibre du système que la spéciation en phase liquide.

This work is focused on thermodynamic modelling of isobaric vapour-liquid-liquid equilibrium (VLLE) (homogeneous) and (heterogeneous) for binary, ternary and quaternary systems. This work uses data for organic/aqueous systems; historically these mixtures were used in the production of penicillin and were required to be separated by continuous fractional distillation. Modelling of the separation required phase equilibrium data to be available so that predictions could be made for equilibrium stage temperatures, vapour compositions, liquid compositions and any phase splitting occurring in the liquid phase. Relevant data became available in the literature and work has been carried out to use relevant theories in correlating and predicting as was originally required in the distillation equilibrium stage modelling. All the modelling carried out was at atmospheric pressure. The modelling has been done using an Equation of State, specifically Peng Robinson Styrjek Vera (PRSV), combined with the activity coefficient model UNIversal QUAsi Chemical (UNIQUAC) through Wong Sandler mixing rules (WSMR). The success of all correlations and predictions was justified by minimizing the value of the Absolute Average Deviation (AAD) as defined within the thesis. Initially the integral Area Method and a method called Tangent Plane Intersection (TPI) were used in the prediction of liquid-liquid equilibrium (LLE) binary systems. This work used a modified 2-point search, suggested a 3-point search and has successfully applied both of these methods to predict VLLE for binary systems. It was discovered through the application of the TPI on ternary VLLE systems that the method was strongly sensitive to initial values. This work suggested and tested a Systematic Initial Generator (SIG) to provide the TPI method with realistic initial values close to the real solution and has demonstrated the viability of the SIG on improving the accuracy of the TPI results for the ternary systems investigated. In parallel with the TPI another method the Tangent Plane Distance Function (TPDF) was also investigated. This method is based on the minimisation of Gibbs free energy function related to the Gibbs energy surface. This method consistently showed it was capable of predicting VLLE for both ternary and quaternary systems as demonstrated throughout this work. The TPDF method was found to be computationally faster and less sensitive to the initial values. Some of the methods investigated in this work were also found to be applicable as phase predictors and it was discovered that the TPDF and the SIG methods were successful in predicting the phase regions; however the TPI method failed in identifying the 2 phase region. Applying the techniques described to newly available quaternary data has identified the strengths and weaknesses of the methods. This work has expanded the existing knowledge and developed a reliable model for design, operation and optimisation of the phase equilibria required for prediction in many separation processes. Currently available modelling simulation packages are variable in their predictions and sometimes yield unsatisfactory predictions. Many of the current uses of VLLE models are particularly focused on Hydrocarbon/Water systems at high pressure. The work described in this thesis has demonstrated that an EOS with suitable mixing rules can model and predict data for polar organic liquids at atmospheric and below atmospheric pressure and offers the advantage of using the same modelling equations for both phases.

The study of matter at extreme densities has been a major focus in theoretical physics in the last half-century. The wide spectrum of information that the field produces provides an invaluable contribution to our knowledge of the world in which we live. Most fascinatingly, the insight into the world around us is provided from knowledge of the intangible, at both the smallest and largest scales in existence. Through the study of nuclear physics we are able to investigate the fundamental construction of individual particles forming nuclei, and with further physics we can extrapolate to neutron stars. The models and concepts put forward by the study of nuclear matter help to solve the mystery of the most powerful interaction in the universe; the strong force. In this study we have investigated a particular state-of-the-art model which is currently used to refine our knowledge of the workings of the strong interaction and the way that it is manifested in both neutron stars and heavy nuclei, although we have placed emphasis on the former for reasons of personal interest. The main body of this work has surrounded an effective field theory known as Quantum Hadrodynamics (QHD) and its variations, as well as an extension to this known as the Quark-Meson Coupling (QMC) model, and variations thereof. We further extend these frameworks to include the possibility of a phase transition from hadronic matter to deconfined quark matter to produce hybrid stars, using various models. We have investigated these pre-existing models to deeply understand how they are justified, and given this information, we have expanded them to incorporate a modern understanding of how the strong interaction is manifest. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1458960 / Thesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics, 2010

Le remplacement du disque intervertébral par une prothèse est une procédure chirurgicale innovante au rachis cervical. Le but de notre travail était d'étudier fonctionnement biomécanique de prothèses discales cervicales, en tenant compte de l'effet des éléments anatomiques après implantation, avec un intérêt spécifique pour l'influence de la variation de la géométrie des implants. La modélisation en éléments finis en 3D nous a permis de constater que les déplacements et les contraintes dans la prothèse et dans les facettes articulaires varient en fonction des paramètres géométriques (rayon et centre) dans le cas de des prothèses à emboîtement sphérique. Malgré une grande variabilité interindividuelle in vivo, l'analyse cinématique des radiographies dynamiques de deux séries de patients porteurs de prothèses à emboîtement sphérique différentes nous a permis observer l'influence de la position du centre géométrique sur le centre moyen de rotation en flexion / extension. Le développement de la stéréoradiographie EOS® pour le rachis cervical nous a conduit d'abord à valider l'utilisation de ce système puis a permis d'étudier un type différent de prothèse (à plateau mobile) dans des déplacements 3D. Nos résultats montrent l'importance des paramètres géométriques des prothèses articulées cervicales. L'interaction cinématique de la prothèse implantée avec les autres éléments du segment mobile rachidien suggère l'intérêt de la modélisation personnalisée dans la prise en charge des patients.

<p>This thesis presents a theoretical study of bulk materials using <i>ab initio</i> methods based on the density functional theory (DFT).</p><p>Crystallographic structural phase transformations and phase stability for 5f-dioxides, ABO₃ perovskites, and ABO₄ compounds have been extensively studied. Different approaches such as static total energy calculations, elastic stability and dynamical stability (phonon calculations) criteria have been used to determine the phase stability. As a special case, the lattice dynamics of solid Xe has been studied as a function of pressure.</p><p>Dielectric functions and optical constants have been calculated for solar energy cell system CuIn_1-xGa_xSe₂ with concentrations x=0, 0.25, 0.5 and 1.0 as well as for C₆₀, PbWO₄and δ-AlOOH. The absorption coefficient provides information about the optimum solar energy conversion efficiency. We have derived absorption coefficients for a number of compounds. Comparisons between the calculated and experimental dielectric functions and absorption coefficients have been made.</p><p>The main part of this thesis focuses on the nanolayered ternary compounds M _N+1AX_N(MAX), where N = 1, 2 or 3, M is an early transition metal, A is an A-group (mostly IIIA and IVA) element, and X is either C and/or N. These ternary carbides and nitrides combine unusual properties of both metals and ceramics. They exhibit high hardness, but fully reversible plasticity, and negligible thermoelectric power. These excellent properties make the MAX phases another new class of materials with versatile technological applications. Our work presents a systematic study of the electronic, bonding, elastic and optical properties of the MAX phases. A new MAX phase-Ti₄SiC_3,is calculated to be stable, and at the same time also been synthesized by experimentalists. Surface energy calculations have also been performed for the (0001) surface of the Ti-Si-C system. The general relations between the electronic structure and materials properties of the MAX phases have been elaborated in the thesis.</p>

This thesis presents a theoretical study of bulk materials using ab initio methods based on the density functional theory (DFT). Crystallographic structural phase transformations and phase stability for 5f-dioxides, ABO3 perovskites, and ABO4 compounds have been extensively studied. Different approaches such as static total energy calculations, elastic stability and dynamical stability (phonon calculations) criteria have been used to determine the phase stability. As a special case, the lattice dynamics of solid Xe has been studied as a function of pressure. Dielectric functions and optical constants have been calculated for solar energy cell system CuIn1-xGaxSe2 with concentrations x=0, 0.25, 0.5 and 1.0 as well as for C60, PbWO4 and δ-AlOOH. The absorption coefficient provides information about the optimum solar energy conversion efficiency. We have derived absorption coefficients for a number of compounds. Comparisons between the calculated and experimental dielectric functions and absorption coefficients have been made. The main part of this thesis focuses on the nanolayered ternary compounds M N+1AXN (MAX), where N = 1, 2 or 3, M is an early transition metal, A is an A-group (mostly IIIA and IVA) element, and X is either C and/or N. These ternary carbides and nitrides combine unusual properties of both metals and ceramics. They exhibit high hardness, but fully reversible plasticity, and negligible thermoelectric power. These excellent properties make the MAX phases another new class of materials with versatile technological applications. Our work presents a systematic study of the electronic, bonding, elastic and optical properties of the MAX phases. A new MAX phase-Ti4SiC3, is calculated to be stable, and at the same time also been synthesized by experimentalists. Surface energy calculations have also been performed for the (0001) surface of the Ti-Si-C system. The general relations between the electronic structure and materials properties of the MAX phases have been elaborated in the thesis.

Distributed ledger technology (DLT) stands to benefit industries such as financial services with transparency and censorship resistance. DLT systems need to be scalable to handle mass user adoption. Mass user adoption is required to demonstrate the true value of DLT. This dissertation first analyses scalability in ethereum and EOS. Currently, ethereum 1.0 uses proof of work (PoW) and handles only 14 transactions per second (tps) compared to Visa's peak 47 000 tps. Ethereum 2.0, known as Serenity, introduces sharding, proof of stake (Casper), plasma and state channels in and effort to scale the system. EOS uses a delegated proof of stake (DPoS) protocol, where 21 super-nodes, termed ‘block producers' (BPs), facilitate consensus, bringing about significant scalability improvements (4000 tps). The trade-off is decentralisation. EOS is not sufficiently decentralised because the BPs yield significant power, but are not diverse. This dissertation conducts an empirical analysis using unsupervised machine learning to show that there is a high probability collusion is occurring between certain BPs. It then suggests possible protocol alterations such as inverse vote weighting that could curb adverse voting behaviour in DPoS. It further analyses whether universities are suitable BP's before mapping out required steps for universities to become block producers (leading to improved decentralisation in EOS)

En la presente tesis se plantea el modelado del equilibrio entre fases de mezclas de importancia en biorrefinerías, y el desarrollo de módulos de simulación de procesos y productos. El modelo termodinámico empleado es la Ecuación de Estado a Contribución Grupal con Asociación (gca-eos) que ha sido desarrollada y exitosamente aplicada al procesamiento de mezclas derivadas de sustratos vegetales y de sistemas a alta presión por el grupo de Termodinámica de Procesos de plapiqui. La gca-eos es robusta para la representación, tanto a baja como alta presión, de sistemas altamente no ideales que presenten asimetría en tamaño y energética y con presencia de interacciones de tipo puente hidrógeno, generalmente presentes en mezclas procedentes del procesamiento de productos naturales. Su carácter a contribución grupal facilita la predicción de compuestos complejos y mezclas a los que se les desconoce sus propiedades, como también frecuentemente ocurre con los de origen natural. Dadas las características favorables de este modelo se propone su extensión para cubrir un número mayor de grupos funcionales típicos del procesamiento en biorrefinerías y una mejor descripción de las interacciones asociativas que pueden presentar el agua, alcoholes, compuestos nitrogenados y aromáticos. Teniendo en cuenta esta premisa se implementaron algoritmos de cálculo termodinámico que fueron incorporados a simuladores de procesos, con énfasis en equipos involucrados en la purificación de biocombustibles, como por ejemplo equipos de destilación flash, columnas de destilación y extractores líquido-líquido. La presente tesis se desarrolla en 8 capítulos. Luego de un apartado introductorio, el capítulo 2 describe el modelo termodinámico gca-eos, destacando leyes físicas que lo sustentan ya que resultan una herramienta sólida para generar las estrategias de parametrización desarrolladas en esta tesis. Los siguientes capítulos, muestran la extensión del modelo a las distintas familias de compuestos orgánicos estudiados. Específicamente, el capítulo 3 trata la extensión la gca-eos, a hidrocarburos aromáticos en sistemas que involucren alcoholes alifáticos y agua. El capítulo 4 por su parte, discute una nueva definición de los grupos fenólicos en sistemas con hidro - carburos aromáticos, alifáticos y agua. Los capítulos 5 y 6 discuten la parametrización de sistemas nitrogenados: el primero define los nuevos grupos amino, y si interacción con hi - drocarburos y alcoholes, mientras que en el segundo se incluye mezclas acuosas de estos compuestos y se prueba la capacidad predictiva de la gca-eos en soluciones acuosas de alcanolaminas. Siendo estas últimas un reconocido solvente para la remoción de gases ácidos también presentes en el procesamiento, tanto bio- como termo-químico, de biomasa. Por último, el capítulo 7 trata el desarrollo de un módulo de simulación de columnas trifásicas. Se desarrollan las ecuaciones básicas que permiten adaptar un algoritmo tradicional de destilación líquido-vapor para considerar la posible existencia de dos fases líquidas. Como caso de estudio, se analiza una columna de remoción de metanol en el contexto del proceso supercrítico de producción de biodiesel. / Phase equilibrium modeling of mixtures of importance in biorefineries, and the development of process simulation modules and products are presented in this thesis. The thermodynamic model chosen is the Group Contribution with Association Equation of State (gca-eos). This model has been developed by the group of Process Thermodynamics in plapiqui and successfully applied to model processes of mixtures of vegetable substrates and high-pressure systems. The gca-eos is capable to model systems of highly non-ideal mixtures, at low or high pressures, which exhibit important energetic and size asymmetry. Also the model is able to handle molecules that present h-bond interactions, characteristic of natural products mixtures. Moreover, its group contribution formulation allows the predictions of unknown properties of complex compounds and mixtures, as in the case of natural compounds. These characteristics encourage an extension of its parameter table to cover a greater number of functional groups that are common in biorefineries processes. Another goal of this thesis was to obtain a better description of associative interactions present in mixtures of water, alcohols, with aromatic and nitrogen compounds. With this premise, thermodynamic calculation algorithms were incorporated into process simulators, with emphasis on equipment involved in the purification of biofuels, such as flash distillation equipment, distillation columns and liquid–liquid extractors. This thesis is presented in eight chapters. After an introductory section, Chapter 2 describes the mathematical formulation of the gca-eos, with emphasis on underlying physical laws which generate robust parameterization strategies developed in this dissertation. The following chapters show the extension of this model to different families of organic compounds studied in this work. Chapter 3 addresses the extension of the model to aromatic hydrocarbons in systems with water and aliphatic alcohols. Chapter 4 discuss a new definition of the phenolic group present in systems with aromatic and aliphatic hydrocarbons and water. Chapters 5 and 6 discuss the parameterization of amine groups: the first one defines new amine groups and its interaction with aliphatic hydrocarbons and alcohols, while the second one includes aqueous amine mixtures, and the predictive capability of the gca-eos is tested with aqueous alkanolamine solutions. Finally, Chapter 7 shows the development of a simulation module of a three phase distillation column. Basic equations that enable a typical vapor–liquid distillation algorithm to represent the existence of two liquid phases are presented. Furthermore, a methanol stripping column in the context of supercritical biodiesel production is analyzed as a case of study.

This dissertation presents the creation of slab coupled optical sensors (SCOS) for electric field sensing applications. SCOS devices utilize the benefits of an optical fiber system for high bandwidth and low electromagnetic interference. These sensors are fabricated by means of mode coupling between a small section of D-shaped optical fiber (D-fiber) with a multi-mode electro-optic slab waveguide. Electric field detection is accomplished by monitoring the behavior of the resonances, seen as transmission dips in the D-fiber transmission, as they shift with electric fields. The novelties of SCOS devices include their small compact nature, potential for sensor multiplexing and a dielectric structure allowing low electromagnetic interference. The SCOS developed in this work been used to measure fields as low as 30 V/m with 1 kHz resolution bandwidth and a high degree of linearity. Due to their compact size they are capable of placement within devices to measure interior electric fields immeasurable by other sensors that are either too large for internal placement or disruptive of the internal fields due to metallic structure. Wavelength multiplexing allows multiple sensors to be placed on a single fiber for mapping electric fields at multiple instances. As an extension, SCOS multiplexing allows the potential for 3-d field sensing by use of multiple electro-optic crystals having orthogonal orientations of the electro-optic axis. This work performs a thorough analysis of SCOS design in order to optimize sensor efficiency for its various applications. Furthermore, the straightforward fabrication process for these sensors is outlined for the development of future uses of these sensors.