Dissertations / Theses on the topic 'ESS modelling'

L’Splicing de les molècules d’ARN és el procés pel qual les seqüències interposades (“introns”) s’eliminen, i les seqüències restants es concatenen per a formar l’ARN madur. La investigació recent mostra que gairebé tots els gens amb splicing es veuen afectats per splicing alternatiu. Aquí, en primer lloc definim la longitud mínima d’un oligomer d’ARN per a funcionar com a lloc d’unió d’un factor d’splicing. A continuació, explorem la capacitat d’aquests oligomers per a predir estructures completes exó-intró. Destaquem els oligomers que són més informatius per a això, i demostrem que la mateixa precisió com en enfocaments anteriors es pot aconseguir amb menys oligomers. L’observació de que aquest enfocament és lluny de predir amb exactitud tota l’estructura exó-intró ens va portar a investigar els factors que juguen un paper en l’splicing co-transcripcional. Demostrem que els nucleosomes es col.loquen preferentment en els exons i plantegem la hipòtesi que juguen un paper en les decisions de l’splicing. A continuació, introduïm el “completed splicing index” i concluem que l’splicing co-transcripcional és molt generalitzat. A més, l’splicing co-transcripcional mostra vincles amb l’organització de la cromatina. A la llum d’aquests resultats, es van supervisar els canvis de la cromatina en exons diferencialment inclosos en dos teixits. Hem descobert una varietat de marques de les histones, però no totes, mostrant un comportament significativament diferent en els exons més inclosos i més exclosos. Las marques més destacades que apareixen són H3K9ac i dos estats de metilació de lisina 4.
Splicing of RNA molecules is the process, by which intervening sequences (“introns”) in the primary transcript are excised, and the remaining sequences (“exons”) are concatenated to form the mature RNA. Recent evidence shows that almost all spliced genes are affected by alternative splicing. Here, we define the minimal length of RNA oligomers that can sensibly be called splicing factor binding sites. Then, we explore the capacity of these oligomers to predict complete exon-intron structures. We highlight those oligomers that are most informative for this and show, that equal accuracy as in previous approaches can be achieved with less RNA oligomers. The observation, that this approach falls short of accurately predicting the entire exon-intron structure, led us to investigate determinants linked to co-transcriptional splicing. We show that nucleosomes are preferentially positioned on exons and hypothesize that they play a role in splicing decisions. We then introduce the “completed splicing index” and conclude that co-transcriptional splicing is very wide-spread in humans. Furthermore co-transcriptional splicing exhibits links to chromatin organization. In the light of these results, we go on to monitor chromatin changes on differentially included exons in pair-wise tissue comparisons. We find a variety of histone marks, but not all, showing significantly different behavior on up- and downregulated exons. The most prominently appearing marks are H3K9ac and two lysine 4 methylation states.

This research project investigated the option of steelmaking with the ESS furnace by using computational modelling to estimate steady state decarburisation rates. It focused on understanding metallurgical phenomena that would dictate refining rates of molten pig iron with iron ore. The results obtained are aimed at designers and potential users of the furnace technology to improve their understanding of the expected steady-state process behaviour. A mass-and-energy-balance model with a decarburisation sub-model was developed to estimate feed material requirements for steady state operation. Modelling and simulation results suggest that it may not be possible to produce steel under the conditions proposed. However, the furnace still holds potential if ideal operational conditions are understood and applied. Modelling also gave insight into which areas areas of concern, such as bubble formation in the furnace’s channel induction heaters, and necessity for a well designed refractory lining to contain heat and allow the process to operate at a stable condition under the conditions proposed. Keywords: ESS furnace, steelmaking, metallurgical analysis, modelling, mass and energy balance, decarburisation kinetics
Dissertation (MEng)--University of Pretoria, 2020.
Materials Science and Metallurgical Engineering
MEng
Unrestricted

Mestrado em Engenharia Química
As emissões de dióxido de carbono têm hoje uma grande importância na indústria de engenharia química, pelo que a sua captura e armazenamento são uma importante área de investigação. Os líquidos iónicos têm sido estudados como solventes (“green solvents”) para a separação de gases e captura de dióxido de carbono. Os líquidos iónicos são uma nova classe de solventes orgânicos, que devido aos seus catiões orgânicos assimétricos e aos aniões inorgânicos, não podem constituir uma estrutura cristalina, permanecendo assim no estado líquido à temperatura ambiente ou temperaturas próximas desta. Estes compostos apresentam uma vasta gama de propriedades interessantes, tais como a alta estabilidade térmica; o estado líquido numa grande amplitude térmica; a boa solvatação, tanto para compostos polares como não polares; e uma das mais interessantes, colocando-os como uma alternativa viável para substituir os solventes orgânicos voláteis, a sua pressão de vapor desprezável. Outra grande vantagem destes solventes "neotéricos" é a possibilidade de modelar as suas propriedades, através da infinita combinação de catiões e aniões, permitindo desenhar os líquidos iónicos de acordo com os objectivos específicos de uma operação particular melhorando o seu desempenho. Já foram aplicadas várias equações de estado para descrever a solubilidade do dióxido de carbono nos líquidos iónicos (equilíbrio líquidovapor), tais como a PC-SAFT, soft-SAFT, Peng-Robinson, Krichevsky- Kasarnovsky, entre outras equações de estado. Neste trabalho, dados experimentais para o equilíbrio líquido-vapor do sistema de dióxido de carbono + 1-alquil-3-metilimidazólio bis(trifluorometilsulfonil)imida foram modelados pela primeira vez com a equação do estado Cubic Plus Association (CPA EoS), em que os parâmetros da equação são obtidos através do ajuste de dados experimentais de pressão de vapor e densidade. Com o objectivo de estudar a solubilidade do dióxido de carbono noutros compostos, foram também medidos os equilíbrios líquidovapor dos sistemas dióxido de carbono + dissulfureto de carbono e dióxido de carbono + tetraclorometano, numa célula de alta pressão, e os dados experimentais obtidos foram igualmente modelados com a CPA EoS. A equação de estado CPA já demonstrou ser uma ferramenta termodinamicamente flexível tendo descrito correctamente o equilíbrio líquidovapor de misturas contendo componentes associativos e não associativos distribuídos por diferentes fases fluidas. Mostra-se que este modelo permite uma boa descrição dos dados experimentais disponíveis. ABSTRACT: Carbon dioxide emissions have today a great importance in the chemical engineering industry, so its capture and storage are an important field of research. Ionic liquids have been studied as green solvents in gases separation and for carbon dioxide capture. Ionic liquids are a new class of organic solvents that due to their asymmetric organic cations and organic or inorganic anions cannot form an ordered crystal and therefore remain liquid at or near room temperature. These compounds present a wide range of interesting properties, such as high thermal stability, large liquid temperature range, good solvation both for polar and non polar compounds, and one of the most interesting, putting them as a viable and ambient friendly alternative to replace the volatile organic solvents, is their negligible vapor pressure. Other major advantage of these “neoteric” solvents is the possibility of fine tune their properties through the endless combination of cations and anions. This designer characteristic allows one to build task-specific ionic liquids that have an enhanced performance for specific operations. Several equations of state have been applied to describe the carbon dioxide solubility in ionic liquids (vapor-liquid equilibrium) such PC-SAFT, soft- SAFT, Peng-Robinson EoS, Krichevsky–Kasarnovsky EoS, among others. In this work, the experimental vapour-liquid equilibrium data of the systems carbon dioxide + 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ionic liquids were modelled for the first time with the Cubic plus Association Equation of State (CPA EoS) with the EOS parameters fitted to vapor pressure and densities of the ionic liquids. In addition, it was used a high pressure cell to measure the vapour-liquid equilibrium of the binary systems carbon dioxide + carbon disulphide and carbon dioxide + carbon tetrachloride and the experimental data obtained were also modelled with the CPA EoS. The CPA EoS had already demonstrated to be a flexible thermodynamic tool for correctly modelling the phase equilibrium of mixtures containing both associative and non-associative components distributed by different fluid phases. It is shown that this model allows for a very good description of the experimental data available.

Mestrado em Engenharia Química
Os hidrocarbonetos aromáticos policíclicos (PAHs) constituem uma família de compostos caracterizada por possuírem dois ou mais anéis aromáticos condensados. São no geral referenciados de contaminantes ambientais porque estão associados à combustão incompleta de materiais orgânicos, como por exemplo, a queima de combustíveis fosseis, incineração de resíduos e derrames de petróleo. O estudo da solubilidade destes compostos em misturas aquosas é de grande importância, devido ao impacto que estes compostos têm na saúde pública e no meio ambiente, dado as suas propriedades cancerígenas. Neste trabalho, a capacidade da equação de estado CPA para modelar a solubilidade em meio aquoso de vários PAHs numa ampla gama de temperatura, foi avaliada. Esta equação de estado combina o termo Soave-Redlich-Kwong (SRK) para descrever as interações físicas com a contribuição de associação proposta por Wertheim, também usada em outras equações de estado, tais como as diferentes versões da SAFT. A CPA EoS já foi aplicada com sucesso a sistemas aquosos com alcanos, compostos aromáticos e álcoois. Os resultados obtidos são muito próximos dos valores encontrados na literatura, sugerindo que a CPA EoS é um modelo adequado para correlacionar soluções aquosas de moléculas complexas de poluentes orgânicos. ABSTRACT: The polycyclic aromatic hydrocarbons (PAHs) are a family of compounds characterized by having two or more aromatic rings condensed. They are referenced in general because they are environmental contaminants associated with the incomplete combustion of organic materials, such as the burning of fossil fuels and incineration of waste, and oil spills. The solubility of these xenobiotics in aqueous mixtures must be monitored due to their impact on public health and the environment, because of their carcinogenic properties and their ubiquity in the environment. In this work, the ability of the Cubic-plus-Association equation of state (CPA EoS) for modelling the aqueous solubility of several PAHs in a wide temperature range was evaluated. This equation of state combines the Soave-Redlich-Kwong (SRK) EoS for describing the physical interactions with the association contribution proposed by Wertheim, also used in other associating equations of state, such as the different versions of SAFT. The CPA EoS had already been successfully applied to aqueous systems with alkanes, aromatics and alcohols. The results obtained are in very close agreement with the literature data, suggesting that the CPA EoS is an adequate model for correlating aqueous solutions of complex molecules of organic pollutants.

The Event Refinement Structures (ERS) approach augments the Event-B formal method with hierarchical diagrams, providing explicit support for control fow and refinement relationships. ERS was originally designed to decompose the atomicity of the events in Event-B and later enriched with control flow combinators. Combining graphical workflow approaches with formal methods has been a subject of interest in both industry and academia, resulting in a diversity of approaches. In this thesis, we present an approach for workflow modelling that addresses both control flow and data handling. ERS is used for control flow, while Event-B mathematical notation supports the data handling. This separation simplifies the modelling by avoiding an extensive number of patterns, though separation does not mean the independence of control flow from data handling. The dependency is achieved by the ERS semantics, which are acquired by transforming the diagrams to Event-B. This combination not only benefits from the verification capabilities of Event-B and the graphical nature of ERS, but also supports incremental modelling through refinement and hierarchy. Our studies resulted in extending the ERS approach to support more flexible behaviour like unbounded replication and exception handling. Unbounded replication is needed when the number of instances of a flow to be executed is unknown and additional instances can be initiated during execution. We also enhance some of the existing ERS combinators such as the loop. We validate our approach and extensions by applying them to two complex work flows, the fire dispatch system and the travel agency booking system. Finally, we extend the ERS formal language with new translation rules to support our new ERS extensions. We formally dene the new translation rules of ERS to Event-B, using the Augmented Backus-Naur Form (ABNF), to be easily integrated in the ERS plug-in. The ERS plug-in is a tool providing automatic generation of part of the Event-B model representing types and sequencing. We also evaluate the ERS combinators in control flow modelling against already published criteria.

Absorption Heat Pumps (AHP) have been developed since the late 19th century. They enable to produce cooling and heating directly from a heat source, unlike Compression Heat Pumps that require mechanical work. In the context of scarcity of resources and global warming, the company Helioclim develops solar air conditioning using an Absorption Heat Pump. The heat is gathered at rooftop solar concentrators and powers an ammonia-water AHP. The present study proposes an EES model of Helioclim’s AHP allowing assessing its performances under various operating conditions. Another aspect developed is the Modelling of the whole system (from solar energy to the economic assessment) in order to find the best parameters to propose to a potential client. Regarding EES model, three existing EES examples of AHP have been used. Those models, ranging from the simple single-stage ammonia AHP to a more complex GAX-cycle, did not correspond exactly to the features of Helioclim’s cycle. Therefore, a new model has been built: the position of the GAX and its connections to the other heat exchangers have been adapted and a recirculation in the generator has been proposed in order to correspond to Helioclim’s design. The model obtained is then used to assess the improvement of the performances with the GAX. It is also compared to the available experimental data. In the present study, a software program representing the whole solar air conditioning system is also developed, integrating the previous EES model. The software program considers the solar energy gathered by the collectors and deduces the energy transmitted to the heat pump. The EES model is then used to assess the performances of the heat pump in the operating conditions, allowing determining the produced cooling and heating. An economic and energy synthesis is produced, summarizing effectively the parameters and economic advantages of the installation. This software program allows sizing an installation for a client much more quickly than before.

To assess the usefulness of a remote sensing approach to soil moisture monitoring in desert regions, a time series of ERS-1 and ERS-2 SAR images were acquired between March 1995 and April 1998 of the north-eastern desert of Jordan. Previous research has demonstrated the sensitivity to soil moisture and surface roughness of the backscatter coefficient of the ERS SAR system. The following objectives were addressed: (1) To assess and exploit the ability of the ERS SAR instrument to monitor geomorphological and hydrological changes in the desert environment. (2) To calibrate theoretical microwave scattering models using field reference data (soil moisture, surface roughness, soil texture, climatic parameters and vegetation) and assess their application to desert environments. (3) To simulate the dependence of the backscatter coefficient on soil moisture fluctuations and surface roughness changes with the aim of improving the understanding of microwave interactions with desert surfaces. (4) To investigate the potential for extraction of quantitative soil moisture estimates from ERS SAR data. Analysis of multitemporal backscatter coefficients, expressed in decibels (dB), for some desert surfaces show fluctuations of up to 6 dB during or after periods of rainfall. Basalt boulder or stone surfaces show very stable backscatter properties regardless of soil moisture conditions. This is because the roughness parameter dominates the scattering mechanism. Detailed analysis of surface roughness measurements and calculations are presented. To understand the scattering processes, the physical optics (PO), geometric optics (GO), small perturbation (SP) and integral equation models (IEM) were calibrated using field data. The results show the limitations of using the PO, GO and SP models in this natural environment, caused by the restrictive model validation domains. The calibration of the IEM yielded much better results, correlation coefficients greater than 0.8 were achieved between predicted and observed backscatter coefficients. Retrieval of soil moisture estimates with the IEM yielded a confidence level of 80%.

The interest in sustainable investing has increased significantly during recent years. Asset managers and institutional investors are urged to invest more sustainable from their stakeholders, reducing their investment universe. This thesis has found that sustainable investments have a different linear dependence structure compared to the regional markets in Europe and North America, but not in Asia-Pacific. However, the largest drawdowns of an sustainable compliant portfolio has historically been lower compared to the a random market portfolio, especially in Europe and North America.
Intresset för hållbara investeringar har ökat avsevärt de senaste åren. Fondförvaltare och institutionella investerare är, från deras intressenter, manade att investera mer hållbart vilket minskar förvaltarnas investeringsuniversum. Denna uppsats har funnit att hållbara investeringar har en beroendestruktur som är skild från de regionala marknaderna i Europa och Nordamerika, men inte för Asien-Stillahavsregionen. De största värdeminskningarna i en hållbar portfölj har historiskt varit mindre än värdeminskningarna från en slumpmässig marknadsportfölj, framförallt i Europa och Nordamerika.

The present work is focused on the design of a solid oxide cell stack that mainly works in electrolysis mode. The framework of the activity is the energetic issue related to the renewable sources management and storage capabilities. The analysis starts observing the energetic issue from an alternative standpoint that emphasizes the ethical aspects and instills in the reader the secondary importance of the efficiency respect to the feasibility and the robustness of the devices. In order to predict the stack performance, a new numerical solver has been developed based on open source tool. This multi-physic solver can handle complete SOC stack both in fuel cell mode and in electrolysis mode. As a part of this activity an insight concerning SOC Electrochemical Impedance Spectroscopy physical simulation has been done. This part of the solver can be coupled with additional plugins and provides the basis for the impedance analysis of the low frequency part of the SOC spectrum. Basing on pragmatic approach a new stack design was proposed and technical drawings have been released. The stack is based on tubular cells considering some peculiarity of the planar configuration especially concerning charge transfer between electrodes and external current takes. Some simulations have been run in order to validate the main assumptions of the design process.

The work presented in this thesis leads to the formulation of a dynamic mathematical model of an immersed membrane bioreactor (iMBR) for wastewater treatment. This thesis is organised into three parts, each one describing a different set of tasks associated with model development and simulation. In the first part, the Author qualitatively and quantitatively compares various published activated sludge models, i.e. models of biochemical processes associated with bacterial growth, decay, lysis and substrate utilisation in activated sludge systems. As the thesis is focused on modelling membrane bioreactors (MBRs) which are known to experience membrane fouling as a result of adsorption of biopolymers present in the bulk liquid onto and within the membrane, all activated sludge models considered in this thesis are able to predict, with various levels of accuracy, the concentrations of biopolymeric substances, namely soluble microbial products (SMP) and extracellular polymeric substances (EPS). Some of the published activated sludge models dedicated to modelling SMP and EPS kinetics in MBR systems were unable to predict the SMP and EPS concentrations with adequate levels of accuracy, without compromising the predictions of other sludge and wastewater constituents. In other cases, the model equations and the assumptions made by their authors were questionable. Hence, two new activated sludge models with SMP and EPS as additional components have been formulated, described, and simulated. The first model is based on the Activated Sludge Model No. 1 (ASM1) whereas the second model is based on the Activated Sludge Model No. 3 (ASM3). Both models are calibrated on two sets of data obtained from a laboratory-scale system and a full-scale system and prove to be in very good agreement with the measurements. The second part of this thesis explains the development of two membrane fouling models. These models are set to describe the loss of membrane permeability during filtration of various solutions and suspensions. The main emphasis is placed on filtration of activated sludge mixtures, however the models are designed to be as general as feasibly possible. As fouling is found to be caused by a large number of often very complex processes which occur at different spatial as well as temporal scales, the two fouling models developed here have to consider a number of significant simplifications and assumptions. These simplifications are required to balance the model's accuracy, generality and completeness with its usability in terms of execution times, identifiability of parameters and ease of implementation in general purpose simulators. These requirements are necessary to ascertain that long term simulations as well as optimisation and sensitivity studies performed in this thesis either individually on fouling models or on the complete model of a MBR can be carried out within realistic time-scales. The first fouling model is based on an idea that fouling can be subdivided into just two processes: short-term reversible fouling and long-term irreversible fouling. These two processes are described with two first order ordinary differential equations (ODEs). Whilst the first model characterises the membrane filtration process from an observer's input-output point of view without any rigorous deterministic description of the underlying mechanisms of membrane fouling, the second model provides a more theoretical and in-depth description of membrane fouling by incorporating and combining three classical macroscopic mechanistic fouling equations within a single simulation framework. Both models are calibrated on a number of experimental data and show good levels of accuracy for their designated applications and within the intended ranges of operating conditions. In the third part, the first developed biological model (CES-ASM1) is combined with the behavioural fouling model and the links between these two models are formulated to allow complete simulation of a hollow fibre (HF) immersed membrane bioreactor (iMBR). It is assumed that biological processes affect the membrane through production of mixed liquor suspended solids (MLSS), SMP and EPS which cause pore blockage, cake formation, pore diameter constriction, and affect the specific cake resistance (SCR). The membrane, on the other hand, has a direct effect on the bulk liquid SMP concentration due to its SMP rejection properties. SMP are assumed to be solely responsible for irreversible fouling, MLSS is directly linked to the amount of cake depositing on the membrane surface, whereas EPS content in activated sludge affects the cake's SCR. Other links provided in the integrated MBR model include the effects of air scouring on the rate of particle back-transport from the membrane surface and the effects of MLSS concentration on oxygen mass transfer. Although backwashing is not described in great detail, its effects are represented in the model by resetting the initial condition in the cake deposition equation after each backwash period. The MBR model was implemented in Simulink® using the plant layout adopted in the MBR benchmark model of Maere et al. [160]. The model was then simulated with the inputs and operational parameters defined in [36, 160]. The results were compared against the MBR benchmark model of Maere et al. [160] which, contrary to this work, does not take into account the production of biopolymers, the membrane fouling, nor any interactions between the biological and the membrane parts of an MBR system.

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.

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.

A dust layer, especially based on high-resistivity dust, at the collecting electrodes may cause a back corona discharge in electrostatic precipitators (ESP). It can significantly reduce the ESP efficiency and as a result cause ecological damages. To study the dust layer influence inside ESPs, it is necessary to derive an adequate model of the ESP precipitation process with a dust layer at the collecting electrode. The research of the present thesis is focused on stationary studies of the precipitation process with a dust layer at the collecting electrode in ESPs. Three mathematical models are proposed as a description of the precipitation process with a dust layer at the collecting electrode. The models are based on Maxwell’s equations and the finite element method (FEM). COMSOL Multiphysics software is used for their implementation. In all models the dust layer has constant conductivity and the air region has constant ion mobility. In the first model there are no coupling conditions, which is required in mathematics, are given between the two regions. The solution found by COMSOL Multiphysics does not provide physically acceptable coupling conditions. In the second model, a continuous transition zone is introduced between the two regions so that no coupling conditions are required. With the large derivatives in the transition zone, the nonlinear solver in COMSOL Multiphysics does not converge. Finally, in the third model, the dust layer and the grounded collecting electrode are replaced with a boundary condition for the air region. The properties of the third model are investigated, and these models can be used to study the influence of the dust layer. The results of these investigations are reported and discussed.

L’oceanografia per satèl•lit ha esdevingut una integració consolidada de les tècniques convencionals de monitorització in situ dels oceans. Un coneixement precís dels processos oceanogràfics i de la seva interacció és fonamental per tal d’entendre el sistema climàtic. En aquest context, els camps de salinitat mesurats regularment constituiran directament una ajuda per a la caracterització de les variacions de la circulació oceànica global. La salinitat s’utilitza en models oceanogràfics predictius, pero a hores d’ara no és possible mesurar-la directament i de forma global. La missió Soil Moisture and Ocean Salinity (SMOS) (en català, humitat del sòl i salinitat de l’oceà) de l’Agència Espacial Europea pretén omplir aquest buit mitjançant la implementació d’un satèl•lit capaç de proveir aquesta informació sinòpticament i regular. Un nou instrument, el Microwave Imaging Radiometer by Aperture Synthesis (MIRAS) (en català, radiòmetre d’observació per microones per síntesi d’obertura), ha estat desenvolupat per tal d’observar la salinitat de la superfície del mar (SSS) als oceans a través de l’adquisició d’imatges de la radiació de microones emesa al voltant de la freqüència de 1.4 GHz (banda L). SMOS portarà el primer radiòmetre orbital, d’òrbita polar, interferomètric 2D i es llençarà a principis de 2009. Així com a qualsevol altra estimació de paràmetres geofísics per teledetecció, la recuperació de la salinitat és un problema invers que implica la minimització d’una funció de cost. Per tal d’assegurar una estimació fiable d’aquesta variable, la resta de paràmetres que afecten a la temperatura de brillantor mesurada s’ha de tenir en compte, filtrar o quantificar. El producte recuperat seran doncs els mapes de salinitat per a cada passada del satèl•lit sobre la Terra. El requeriment de precisió proposat per a la missió és de 0.1 ‰ després de fer el promig en finestres espaciotemporals de 10 dies i de 20x20. En aquesta tesi de doctorat, diversos estudis s’han dut a terme per a la determinació del balanç d’error de la salinitat de l’oceà en el marc de la missió SMOS. Les motivacions de la missió, les condicions de mesura i els conceptes bàsics de radiometria per microones es descriuen conjuntament amb les principals característiques de la recuperació de la salinitat. Els aspectes de la recuperació de la salinitat que tenen una influència crítica en el procés d’inversió són: • El biaix depenent de l’escena en les mesures simulades, • La sensibilitat radiomètrica (soroll termal) i la precisió radiomètrica, • La definició de la modelització directa banda L • Dades auxiliars, temperatura de la superfície del mar (SST) i velocitat del vent, incerteses, • Restriccions en la funció de cost, particularment en el terme de salinitat, i • Promig espacio-temporal adequat. Un concepte emergeix directament de l’enunciat del problema de recuperació de la salinitat: diferents ajustos de l’algoritme de minimització donen resultats diferents i això s’ha de tenir en compte. Basant-se en aquesta consideració, la determinació del balanç d’error s’ha aproximat progressivament tot avaluant l’extensió de l’impacte de les diferents variables, així com la parametrització en termes d’error de salinitat. S’ha estudiat l’impacte de diverses dades auxiliars provinents de fonts diferents sobre l’error SSS final. Això permet tenir una primera impressió de l’error quantitatiu que pot esperar-se en les mesures reals futures, mentre que, en un altre estudi, s’ha investigat la possibilitat d’utilitzar senyals derivats de la reflectometria per tal de corregir les incerteses de l’estat del mar en el context SMOS. El nucli d’aquest treball el constitueix el Balanç d’Error SSS total. S’han identificat de forma consistent les fonts d’error i s’han analitzat els efectes corresponents en termes de l’error SSS mig en diferents configuracions d’algoritmes. Per una altra banda, es mostren els resultats d’un estudi de la variabilitat horitzontal de la salinitat, dut a terme utilitzant dades d’entrada amb una resolució espacial variable creixent. Això hauria de permetre confirmar la capacitat de la SSS recuperada per tal reproduir característiques oceanogràfiques mesoscàliques. Els principals resultats i consideracions derivats d’aquest estudi contribuiran a la definició de les bases de l’algoritme de recuperació de la salinitat.
Satellite oceanography has become a consolidated integration of conventional in situ monitoring of the oceans. Accurate knowledge of the oceanographic processes and their interaction is crucial for the understanding of the climate system. In this framework, routinely-measured salinity fields will directly aid in characterizing the variations of the global ocean circulation. Salinity is used in predictive oceanographic models, but no capability exists to date to measure it directly and globally. The European Space Agency’s Soil Moisture and Ocean Salinity (SMOS) mission aims at filling this gap through the implementation of a satellite that has the potential to provide synoptically and routinely this information. A novel instrument, the Microwave Imaging Radiometer by Aperture Synthesis, has been developed to observe the sea surface salinity (SSS) over the oceans by capturing images of the emitted microwave radiation around the frequency of 1.4 GHz (L-band). SMOS will carry the first-ever, polar-orbiting, space-borne, 2-D interferometric radiometer and will be launched in early 2009. Like whatsoever remotely-sensed geophysical parameter estimation, the retrieval of salinity is an inverse problem that involves the minimization of a cost function. In order to ensure a reliable estimation of this variable, all the other parameters affecting the measured brightness temperature will have to be taken into account, filtered or quantified. The overall retrieved product will thus be salinity maps in a single satellite overpass over the Earth. The proposed accuracy requirement for the mission is specified as 0.1 ‰ after averaging in a 10-day and 2ºx2º spatio-temporal boxes. In this Ph.D. Thesis several studies have been performed towards the determination of an ocean salinity error budget within the SMOS mission. The motivations of the mission, the rationale of the measurements and the basic concepts of microwave radiometry have been described along with the salinity retrieval main features. The salinity retrieval issues whose influence is critical in the inversion procedure are: • Scene-dependent bias in the simulated measurements, • Radiometric sensitivity (thermal noise) and radiometric accuracy, • L-band forward modeling definition, • Auxiliary data, sea surface temperature (SST) and wind speed, uncertainties, • Constraints in the cost function, especially on salinity term, and • Adequate spatio-temporal averaging. A straightforward concept stems from the statement of the salinity retrieval problem: different tuning and setting of the minimization algorithm lead to different results, and complete awareness of that should be assumed. Based on this consideration, the error budget determination has been progressively approached by evaluating the extent of the impact of different variables and parameterizations in terms of salinity error. The impact of several multi-sources auxiliary data on the final SSS error has been addressed. This gives a first feeling of the quantitative error that should be expected in real upcoming measurements, whilst, in another study, the potential use of reflectometry-derived signals to correct for sea state uncertainty in the SMOS context has been investigated. The core of the work concerned the overall SSS Error Budget. The error sources are consistently binned and the corresponding effects in terms of the averaged SSS error have been addressed in different algorithm configurations. Furthermore, the results of a salinity horizontal variability study, performed by using input data at increasingly variable spatial resolution, are shown. This should assess the capability of retrieved SSS to reproduce mesoscale oceanographic features. Main results and insights deriving from these studies will contribute to the definition of the salinity retrieval algorithm baseline.

This thesis documents the modelling of generic Environmental Control System(ECS) of an aircraft in Modelica by utilizing components from free version of theTTECCS (Technical Thermodynamic Environmental Control and Cooling Systems) library. In doing so, components used for developing ECS from the TTECCS library are mathematically verified with theoretical formula in MATLAB. Selected components are investigated with valid input data to initialize the simulation and verify its behaviors with corresponding available data. Hereinafter, the object-oriented modelling method is used to integrate ECS components to develop a functional system. The main function of ECS is to regulate the pressure and temperature inside the cabin to accepted physiology flight safetylevels. Different types of ECS architecture are presented in this document. An ECS developed here is based on the bootstrap system and consists only one cooling unit comprised with the source, pipes, two heat exchanger, compressor, turbine, temper-ature control valve, pressure control valve, and sinks. Dry air(Ideal gas) is used as a medium in the system. Temperature drop along each component corresponds to available A320 cruise flight data in order to calculate the top level parameter and to initialize the components, subsequently an ECS system. Several systematized methods for Object-oriented modelling and system design were studied and steps are extracted accordingly that suits to initiate the procedurefor this project, which is also presented. Time domain simulation is performed inModelica and Dymola. A simplified control system is built to regulate the system, therefore restrained it as a future work to develop real in-flight condition control system of an ECS.Top level parameters were selected within valid customized ranges for developing a performance map of the components. After generating the map, optimal data from the map were taken to initialize final ECS. The simulation results of the final model is then compared to A320 flight data which is comparable in behavior; this was expected. Above all, simulation environment Modelica and free version of TTECCS library components are reliable to develop ECS in order to investigate ECS components behavior and predict cabin conditions before developing a prototype.

Pourquoi des personnes ayant grandi dans des milieux linguistiques différents ne perçoivent-elles un même signal acoustique de la même manière ? Par exemple, il arrive que des auditeurs rapportent avoir entendu des voyelles non présentes dans l'acoustique de mots non-natifs, lorsque ceux-ci ne se conforment pas aux structures sonores permises dans leur langue (épenthèse vocalique perceptive). L'identité de la voyelle épenthétique varie en fonction des langues, mais aussi parmi les langues elles-mêmes. À quel point ce processus est-il dirigé par des informations directement accessibles dans le signal acoustique ? Quelle est la part de contribution de la phonologie native ? Comment sont combinés ces deux éléments lors du calcul du percept ? Deux familles principales de théories ont été proposées : les théories à deux étapes, et les théories à une étape. Les premières proposent une analyse initiale des catégories phonétiques, suivie de réparations faites par une grammaire abstraite. De leur côté, les théories à une étape proposent que tous les facteurs acoustiques, phonétiques, et phonologiques sont intégrés simultanément de manière probabiliste. Dans cette thèse, nous combinons expériences et de modélisation, afin d'évaluer si l'épenthèse est un processus à une ou deux étapes. En particulier, nous examinons ceci en mesurant le rôle des détails acoustiques dans les modulations de l'identité de la voyelle épenthétique. Dans un premier temps, des résultats d'expériences nous montrent que ces modulations sont influencées aussi bien par les détails acoustiques que par des processus phonologiques. Cependant, la plupart de la variation de l'identité de la voyelle épenthétique est expliquée par l'acoustique. De plus, nous présentons un modèle de perception à une étape qui utilise des exemplaires ; celui-ci est capable de reproduire les effets de la coarticulation qui ont été relevés dans les données expérimentales. Ces résultats constituent de l'évidence en faveur des modèles de perception étrangère à une étape. Dans un deuxième temps, nous présentons une implémentation du modèle à une étape proposé par Wilson et al. (2013), en utilisant des modèles HMM-GMM, issus du milieu de la reconnaissance automatique de la parole (RAP). Ces modèles se composent d'un modèle acoustique et d'un modèle de langage, qui déterminent la correspondence acoustique et phonotactique entre la parole et des transcriptions possibles, respectivement. Il nous est alors possible de les ajuster indépendamment afin d'évaluer leur influence relative dans l'épenthèse vocalique perceptuelle. Nous proposons une nouvelle manière d'utiliser ces modèles pour simuler des paradigmes de choix forcés utilisés pour étudier l'épenthèse vocalique chez des participants humains, en utilisant des modèles de langage contraints lors du processus de décodage de la parole. D’abord, nous utilisons cette nouvelle méthode afin de tester si des systèmes de RAP avec des modèles de langage à phonotactique à textit{n}-grammes donnent des résultats plus proches des résultats humains qu'un système de RAP avec un modèle de langage nul. De manière étonnante, les résultats montrent que le système à modèle de langage nul prédit le mieux la performance des participants. Puis, nous évaluons si certains effets traditionnellement attribués à des processus phonologiques peuvent être expliqués par l'acoustique. Bien que les résultats soient prometteurs, nos modèles ne sont capables de reproduire qu'une sous-partie des effets observés chez l'humain. Avant de pouvoir attribuer l'origine de ces effets à des processus phonologiques, il est nécessaire de tester des systèmes de RAP avec des modèles acoustiques plus performants. Nous énumérons des futures pistes de recherche d'utilisation de modèles améliorés, et nous soulignons les avantages de l'utilisation conjointe d'expériences comportementales et modélisations computationnelles afin d'élucider les mécanismes de la perception de la parole étrangère
Why do people of different linguistic background sometimes perceive the same acoustic signal differently? For instance, when hearing nonnative speech that does not conform to sound structures allowed in their native language, listeners may report hearing vowels that are not acoustically present. This phenomenon, known as perceptual vowel epenthesis, has been attested in various languages such as Japanese, Brazilian Portuguese, Korean, and English. The quality of the epenthesized vowel varies between languages, but also within languages, given certain phonemic environments. How much of this process is guided by information directly accessible in the acoustic signal? What is the contribution of the native phonology? How are these two elements combined when computing the native percept? Two main families of theories have been proposed as explanations: two-step and one-step theories. The former advocate an initial parsing of the phonetic categories, followed by repairs by an abstract grammar (e.g., epenthesis), while one-step proposals posit that all acoustic, phonetic, and phonological factors are integrated simultaneously in a probabilistic manner, in order to find the optimal percept. In this dissertation, we use a combination of experimental and modelling approaches in order to evaluate whether perceptual vowel epenthesis is a two-step or one-step process. In particular, we investigate this by assessing the role of acoustic details in modulations of epenthetic vowel quality. In a first part, results from two behavioural experiments show that these modulations are influenced by acoustic cues as well as phonology; however, the former explain most of the variation in epenthetic vowel responses. Additionally, we present a one-step exemplar-based model of perception that is able to reproduce coarticulation effects observed in human data. These results constitute evidence for one-step models of nonnative speech perception. In a second part, we present an implementation of the one-step proposal in Wilson et al. (2013) using HMM-GMM (hidden Markov models with Gaussian mixture models) from the field of automatic speech recognition. These models present two separate components, determining the acoustic and phonotactic matches between speech and possible transcriptions. We can thus tweak them independently in order to evaluate the relative influence of acoustic/phonetic and phonological factors in perceptual vowel epenthesis. We propose a novel way to simulate with these models the forced choice paradigm used to probe vowel epenthesis in human participants, using constrained language models during the speech decoding process. In a first set of studies, we use this method to test whether various ASR systems with textit{n}-gram phonotactics as their language model better approximate human results than an ASR system with a null (i.e., no phonotactics) language model. Surprisingly, we find that this null model was the best predictor of human performance.In a second set of studies, we evaluate whether effects traditionally attributed to phonology may be predictable solely from acoustic match. We find that, while promising, our models are only able to partially reproduce some effects observed in results from human experiments. Before attributing the source of these effects to phonology, it is necessary to test ASR systems with more performant acoustic models. We discuss future avenues for using enhanced models, and highlight the advantages of using a hybrid approach with behavioural experiments and computational modelling in order to elucidate the mechanisms underlying nonnative speech perception

Benzotriazole (BTAH) has been used as a corrosion inhibitor for copper and copper-, based alloys for more than 40 years. It has been successfully employed for the, prevention of both atmospheric corrosion and particularly for the protection of, copper under immersed conditions. Whilst BTAH is an excellent inhibitor in alkaline, solution its efficiency drops off markedly as the pH decreases. It was hypothesized, that a possible way to increase surface adsorption and subsequent better inhibition, over a wide pH range might be through the preparation of derivatives, particularly, carboxybenzotriazoles and alkyl esters of these compounds. In this work the following techniques: weight loss measurements, potentiodynamic, polarisation, SERS spectroscopy, electrochemical impedance spectroscopy and, coulometry were employed to investigate the inhibition efficiency of 4- and 5-, carboxybenzotriazole and their alkyl ester for copper corrosion. Molecular modelling, was also investigated as a tool for inhibitor design. Studies on 4- and 5- carboxybenzotriazole (CBT) showed that the inhibition, efficiency for copper corrosion in aerated acidic sulphate solution of each isomer was, pH, concentration and time dependant. At lower pH the 5-isomer is the better, inhibitor and this behaviour continues at higher pH. The anti-tarnishing test showed, that whilst both isomers exhibited these properties, 5-CBT was once again the, superior inhibitor. It was found that a commercial mixture of the octyl esters of 4- and 5-, carboxybenzotriazole inhibits copper corrosion in sulphate environments open to air., The inhibition efficiency of the ester mixture at the lx10-4 M level (pH - 0) is 98%, which compares very favourably with that for BTAH (- 50%). With respect to other, alkyl esters of 4- and 5-carboxybezotriazole, hexyl, butyl and methyl, it was found, that all of these inlibited copper corrosion in sulphate environments open to air. In, each case the inhibition efficiency is concentration, pH and time dependent. Both, coupon tests and EIS measurements indicate that inhibition efficiency depends on the, length of the alkyl chain. At pH - 0 the inhibition efficiency decreased in the order, octyl >hexyl >butyl >methyl. At higher pH (- 8) the order is reversed. At the 1x104, M level (pH - 0) the inhibition efficiency of each of the alkyl esters is equal to or, better than that for BTAH. At higher pH (- 8) the inhibition efficiency in each case is, reduced in comparison to BTAH. but is still good enough for practical use ( 2 75%)., The inhibitive behaviour of the alkyl esters at low pH can be attributed to, chemisorption through an azole nitrogen of the protonated alkyl esters. The, hydrocarbon chain is also physically adsorbed and the increase in physical adsorption, as the chain is lengthened accounts for the improved inhibition efficiency. Dry films formed by immersing copper in solutions of alkyl esters of, carboxybenzotriazole also inhibit copper corrosion in both strongly acidic (pH - 0), and near neutral (pH - S) sulphate corrodents. The inhibition efficiency depends on, the solvents used to dissolve the esters, solution temperature and immersion time., Aqueous coating solutions furnish the most protective films. Films formed by, CBTAH-BU, CBTAH-HE and CBTAH-OE are more protective than that formed by, BTAH. The inhibition efficiency of the alkyl ester film increases as the alkyl chain is, made longer. Molecular modeling showed that the optimum crude binding energy (Eblnd), between each protonated ester molecule and the surface varied linearly with the alkyl, chain length. The resulting linear correlation between IE% and E bind for compounds, that are structurally similar suggested that the crude binding energy of a single, molecule with copper may be used to predict the inhibition performance of other, compounds constituting a series.

Benzotriazole (BTAH) has been used as a corrosion inhibitor for copper and copper-, based alloys for more than 40 years. It has been successfully employed for the, prevention of both atmospheric corrosion and particularly for the protection of, copper under immersed conditions. Whilst BTAH is an excellent inhibitor in alkaline, solution its efficiency drops off markedly as the pH decreases. It was hypothesized, that a possible way to increase surface adsorption and subsequent better inhibition, over a wide pH range might be through the preparation of derivatives, particularly, carboxybenzotriazoles and alkyl esters of these compounds. In this work the following techniques: weight loss measurements, potentiodynamic, polarisation, SERS spectroscopy, electrochemical impedance spectroscopy and, coulometry were employed to investigate the inhibition efficiency of 4- and 5-, carboxybenzotriazole and their alkyl ester for copper corrosion. Molecular modelling, was also investigated as a tool for inhibitor design. Studies on 4- and 5- carboxybenzotriazole (CBT) showed that the inhibition, efficiency for copper corrosion in aerated acidic sulphate solution of each isomer was, pH, concentration and time dependant. At lower pH the 5-isomer is the better, inhibitor and this behaviour continues at higher pH. The anti-tarnishing test showed, that whilst both isomers exhibited these properties, 5-CBT was once again the, superior inhibitor. It was found that a commercial mixture of the octyl esters of 4- and 5-, carboxybenzotriazole inhibits copper corrosion in sulphate environments open to air., The inhibition efficiency of the ester mixture at the lx10-4 M level (pH - 0) is 98%, which compares very favourably with that for BTAH (- 50%). With respect to other, alkyl esters of 4- and 5-carboxybezotriazole, hexyl, butyl and methyl, it was found, that all of these inlibited copper corrosion in sulphate environments open to air. In, each case the inhibition efficiency is concentration, pH and time dependent. Both, coupon tests and EIS measurements indicate that inhibition efficiency depends on the, length of the alkyl chain. At pH - 0 the inhibition efficiency decreased in the order, octyl >hexyl >butyl >methyl. At higher pH (- 8) the order is reversed. At the 1x104, M level (pH - 0) the inhibition efficiency of each of the alkyl esters is equal to or, better than that for BTAH. At higher pH (- 8) the inhibition efficiency in each case is, reduced in comparison to BTAH. but is still good enough for practical use ( 2 75%)., The inhibitive behaviour of the alkyl esters at low pH can be attributed to, chemisorption through an azole nitrogen of the protonated alkyl esters. The, hydrocarbon chain is also physically adsorbed and the increase in physical adsorption, as the chain is lengthened accounts for the improved inhibition efficiency. Dry films formed by immersing copper in solutions of alkyl esters of, carboxybenzotriazole also inhibit copper corrosion in both strongly acidic (pH - 0), and near neutral (pH - S) sulphate corrodents. The inhibition efficiency depends on, the solvents used to dissolve the esters, solution temperature and immersion time., Aqueous coating solutions furnish the most protective films. Films formed by, CBTAH-BU, CBTAH-HE and CBTAH-OE are more protective than that formed by, BTAH. The inhibition efficiency of the alkyl ester film increases as the alkyl chain is, made longer. Molecular modeling showed that the optimum crude binding energy (Eblnd), between each protonated ester molecule and the surface varied linearly with the alkyl, chain length. The resulting linear correlation between IE% and E bind for compounds, that are structurally similar suggested that the crude binding energy of a single, molecule with copper may be used to predict the inhibition performance of other, compounds constituting a series.

Thesis (MScEng)-- Stellenbosch University, 2013.
ENGLISH ABSTRACT: The simplified Perturbed-Chain Statistical Associating Fluid Theory (sPC-SAFT) is characterised by the dual advantages of decreased computational intensity, while remaining accurate for a variety of systems. Vapour-liquid equilibrium data are used to generate equation of state parameters. However, incorporating monomer fraction data into the parameter regression has long been advocated as a good, or even preferred, practice. Therefore, the monomer fraction data of dilute alcohol-acetone systems were analysed in this study. A small stainless steel sample vessel was constructed with temperature control, manual pressure control and a mechanism for liquid phase analysis via infrared spectroscopy. The performance of the spectrometer was verified by comparison with the ethanol – n-hexane data of von Solms et al. (2007), after which new monomer fraction data were obtained for dilute solutions (between 0.01 and 1.5 mol%) of methanol, ethanol, 1-propanol and 2-propanol in acetone near 23 °C. For dilute alcohol-acetone systems it was found that the propanols had the highest monomer fractions, and methanol the lowest. With increasing alcohol concentration, the monomer fractions decreased exponentially to values of 0.4 and 0.1 for methanol and the other alcohols respectively. The excess availability of hydrogen bond acceptors in the mixtures explains the equivalency observed for ethanol, 1-propanol and 2-propanol. For dilute acetone-alcohol systems it was found that, especially for methanol and ethanol, there was a pronounced trend towards acetone monomer fractions of 1 at infinite dilution. For the acetone – 2-propanol system, a previously unrecorded monomer peak was observed and quantified. Acetone monomer fractions tended to decrease as alcohol chain-length increased, showing that acetone could more easily penetrate the hydrogen bond network of the solvent when the solvent-solvent bonds were weaker. Monomer fraction data were compared to predictions for the sPC-SAFT scheme and parameters combinations published in the literature. The experimental data were accurately modelled using modified association parameters such that the solute associates strongly (εAB≈103 κ≈1), while the solvent parameters were decreased (εAB≈102 κ≈10˗3) to give a weakened solvent association effect. The difficulty for the dilute solute in penetrating the solvent bonding network appeared to be similar to the hydrophobic effect. Two new association schemes were proposed for acetone, assigning a single (N) or two (2N) negative association sites to represent the oxygen valence electron pairs. These schemes showed relative success in modelling acetone as the solvent in the mixture, while not being able to predict acetone monomer fractions when acetone was the solute. For dilute acetone-alcohol systems, the data were best described using the 2B model for acetone, while the best choice of scheme for the alcohol varied from system to system. For dilute alcohol-acetone mixtures it was generally found that a 2B-N model (with modified association parameters) provided the best fit to those experimental data. Accurate modelling below 0.1 mol% was difficult to attain with average errors decreasing to the order of 10% when this area was excluded. In this highly dilute region, not one of the models could describe the rapid change in (monomer fraction) gradient sufficiently while simultaneously offering accurate predictions over the entire experimental range.
AFRIKAANSE OPSOMMING: Die sPC-SAFT of simplified Perturbed-Chain Statistical Associating Fluid Theory toestandsvergelykings word wyd gebruik as gevolg van sy goeie akkuraatheid vir ‘n wye reeks sisteme, ten spyte van verminderde berekeningsintensiteit. Die parameters vir dié toestandsvergelyk word afgelei van faseewewig data, maar monomeer fraksie data word voorgestel vir die verbetering van (veral) die assosiasie parameters. Ten opsigte hiervan, was alkohol-asetoon sisteme bestudeer en hul monomeer fraksies gemeet. ‘n Staal reaktor was ontwerp (met ‘n temperatuurbeheerstelsel sowel as drukbeheer) om vloeistof monsters voor te berei vir analise d.m.v. infrarooi-spektroskopie. Die akkuraatheid van die eksperimentele apparaat is bewys deur nabootsing van etanol – n-heksaan data van von Solms et al. (2007), waarna nuwe monomeer fraksie data gegenereer is vir verdunde mengsels (0.01 tot 1.5 mol%) van metanol, etanol, 1- en 2-propanol met asetoon by 23 °C. Metanol monomeer fraksies het eksponensieël afgeneem na 0.4, terwyl etanol en propanol fraksies afgeneem het na ‘n gemene waarde van ongeveer 0.1. Hierdie tendens word toegeskryf aan ‘n oormaat van toeganklike waterstofbindingontvangers in hierdie mengsels. Vir verdunde asetoon-alkohol sisteme is daar ‘n tendens, (veral vir verdunnings met metanol en etanol) vir die monomer fraksies om te neig na 1 by oneindige verdunning. ‘n Monomeer piek is ook waargeneem vir die asetoon – 2-propanol sisteem. Hierdie piek is nie voorheen gesien in ander studies nie en dit is ook die eerste keer wat sulke data gekwantifiseer is. Daar is bevind dat asetoon monomeer fraksies afneem soos alkohol kettinglengte toeneem. Die gegenereerde monomeer fraksie data word vergelyk met verskeie sPC-SAFT parameterstelle vanuit die literatuur. Oor die algemeen, is die beraamde fraksie veel hoër as die eksperimentele data wanneer die 2B/3B/2C skemas met ‘n nie-assosiërende asetoon molekuul gemodelleer word. Wanneer die 2B parameters van von Solms et al. (2004) gebruik word, toon die beraming ‘n drastiese onderskatting van die data. Om ‘n akkurate beraming van die monomeer fraksie data te kry, moet die assosiasie parameters van die opgeloste stof vermeerder word (met εAB≈103 κ≈1) terwyl die oplosmiddel s’n drasties verswak moet word (met εAB≈102 κ≈10-3). Hierdie patroon kan vergelyk word met die hidrofobiese effek waar die kragte binne die oplosmiddel ‘n netwerk vorm wat die opgeloste stof uitstoot. Twee nuwe assosiasie skemas word ook voorgestel vir asetoon waar onderskeidelik een (N) en twee (2N) negatiewe sones, wat die valenselektroonpare op die suurstofatoom voorstel, aan asetoon geheg word. Hierdie twee skemas het relatiewe sukses getoon in die modellering van verdunde alkohol-asetoon sisteme terwyl dit ‘n swak beskrywing van die verdunde asetoon-alkohol mengsels voorspel het. ‘n Gewysigde 2B asetoon skema gee ‘n goeie beskrywing van die eksperimentele data. In hierdie geval, is die keuse van alkohol skema minder belangrik, terwyl die waardes van die assosiasie parameters verminder moet word. Vir verdunde alkohol-asetoon mengels word daar bevind dat ‘n 2B-N model met nuwe assosiasie parameters die beste passing van die eksperimentele data gee. Daar was ook bevind dat die modelle se akkuraatheid drasties afneem (met fout vermeerdering in die orde van 10%) wanneer die konsentrasie van die opgeloste stof minder as 0.1 mol% is.

In the present work, the deviations in the solubility of CO2, CH4, and N2 at 30 °c in the mixed gases (CO2/CH4) and (CO2/N2) from the pure gas behavior were studied using the dual-mode model over a wide range of equilibrium composition and pressure values in two glassy polymers. The first of which was PI-DAR which is the polyimide formed by the reaction between 4, 6-diaminoresorcinol dihydrochloride (DAR-Cl) and 2, 2’-bis-(3, 4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA). The other glassy polymer was TR-DAR which is the corresponding thermally rearranged polymer of PI-DAR. Also, mixed gas sorption experiments for the gas mixture (CO2/CH4) in TR-DAR at 30°c took place in order to assess the degree of accuracy of the dual-mode model in predicting the true mixed gas behavior. The experiments were conducted on a pressure decay apparatus coupled with a gas chromatography column. On the other hand, the solubility of CO2 and CH4 in two rubbery polymers at 30⁰c in the mixed gas (CO2/CH4) was modelled using the Lacombe and Sanchez equation of state at various values of equilibrium composition and pressure. These two rubbery polymers were cross-linked poly (ethylene oxide) (XLPEO) and poly (dimethylsiloxane) (PDMS). Moreover, data about the sorption of CO2 and CH4 in liquid methyl dietahnolamine MDEA that was collected from literature65-67 was used to determine the deviations in the sorption behavior in the mixed gas from that in the pure gases. It was observed that the competition effects between the penetrants were prevailing in the glassy polymers while swelling effects were predominant in the rubbery polymers above a certain value of the fugacity of CO2. Also, it was found that the dual-mode model showed a good prediction of the sorption of CH4 in the mixed gas for small pressure values but in general, it failed to predict the actual sorption of the penetrants in the mixed gas.

The thesis reports on the application of advanced microanalytical techniques to answer a fundamental open question on the homeostasis of Plasmodium falciparum infected red blood cells, namely how infected cells retain their integrity for the duration of the parasite asexual reproduction cycle. The volume and shape changes of infected cells were measured and characterized at femtolitre resolution throughout the intraerythrocytic cycle using confocal microscopy. Fluorescence lifetime imaging and electron probe X-ray microanalysis were applied for the quantification of intracellular haemoglobin and electrolyte concentrations. The cytomechanical properties of uninfected and infected red cells were studied using a novel optical stretcher device, which enabled individual cells to be trapped and manipulated optomechanically in microfluidic channels. Combined, these methods offered a unique insight into the homeostatic and rheological behaviour of malaria-infected red cells. The results were analysed by comparison with predictions from a detailed physiological model of the homeostasis and volume regulation of infected cells, providing broad support to the view that excess haemoglobin consumptions by the parasite was necessary for the integrity of infected cells (the colloidosmotic hypothesis). The dissertation is introduced with an overview of malaria, red blood cells homeostasis and the changes induced by Plasmodium falciparum infection. In the following, this description is extended to an in-depth theoretical analysis of the infected red blood cell homeostasis, from which the need to characterise certain parameters arises. The subsequent chapters address sequentially the assessment of the haemoglobin and electrolyte concentration, cell shape and volume changes and ultimately alterations in cell elasticity. The experimental part is complemented with a comparison of the resulting data to the predictions from the theoretical analysis and an outlook on future work.

El reactor anaerobio de membranas sumergidas (SAnMBR) está considerado como tecnología candidata para mejorar la sostenibilidad en el sector de la depuración de aguas residuales, ampliando la aplicabilidad de la biotecnología anaerobia al tratamiento de aguas residuales de baja carga (v.g. agua residual urbana) o a condiciones medioambientales extremas (v.g. bajas temperaturas de operación). Esta tecnología alternativa de tratamiento de aguas residuales es más sostenible que las tecnologías aerobias actuales ya que el agua residual se transforma en una fuente renovable de energía y nutrientes, proporcionando además un recurso de agua reutilizable. SAnMBR no sólo presenta las principales ventajas de los reactores de membranas (i.e. efluente de alta calidad, y pocas necesidades de espacio), sino que también presenta las principales ventajas de los procesos anaerobios. En este sentido, la tecnología SAnMBR presenta una baja producción de fangos debido a la baja tasa de crecimiento de los microorganismos implicados en la degradación de la materia orgánica, presenta una baja demanda energética debido a la ausencia de aireación, y permite la generación de metano, el cual representa una fuente de energía renovable que mejora el balance energético neto del sistema. Cabe destacar el potencial de recuperación de nutrientes del agua residual bien cuando el efluente es destinado a irrigación directamente, o bien cuando debe ser tratado previamente mediante tecnologías de recuperación de nutrientes. El objetivo principal de esta tesis doctoral es evaluar la viabilidad de la tecnología SAnMBR como núcleo en el tratamiento de aguas residuales urbanas a temperatura ambiente. Por lo tanto, esta tesis se centra en las siguientes tareas: (1) implementación, calibración y puesta en marcha del sistema de instrumentación, control y automatización requerido; (2) identificación de los parámetros de operación clave que afectan al proceso de filtración; (3) modelación y simulación del proceso de filtración; y (4) desarrollo de estrategias de control para la optimización del proceso de filtración minimizando los costes de operación. En este trabajo de investigación se propone un sistema de instrumentación, control y automatización para SAnMBR, el cual fue esencial para alcanzar un comportamiento adecuado y estable del sistema frente a posibles perturbaciones. El comportamiento de las membranas fue comparable a sistemas MBR aerobios a escala industrial. Tras más de dos años de operación ininterrumpida, no se detectaron problemas significativos asociados al ensuciamiento irreversible de las membranas, incluso operando a elevadas concentraciones de sólidos en el licor mezcla (valores de hasta 25 g·L-1 ). En este trabajo se presenta un modelo de filtración (basado en el modelo de resistencias en serie) que permitió simular de forma adecuada el proceso de filtración. Por otra parte, se propone un control supervisor basado en un sistema experto que consiguió reducir el consumo energético asociado a la limpieza física de las membranas, un bajo porcentaje de tiempo destinado a la limpieza física respecto al total de operación, y, en general, un menor coste operacional del proceso de filtración. Esta tesis doctoral está integrada en un proyecto nacional de investigación, subvencionado por el Ministerio de Ciencia e Innovación (MICINN), con título ¿Modelación de la aplicación de la tecnología de membranas para la valorización energética de la materia orgánica del agua residual y la minimización de los fangos producidos¿ (MICINN, proyecto CTM2008-06809- C02-01/02). Para obtener resultados representativos que puedan ser extrapolados a plantas reales, esta tesis doctoral se ha llevado a cabo utilizando un sistema SAnMBR que incorpora módulos comerciales de membrana de fibra hueca. Además, esta planta es alimentada con el efluente del pre-tratamiento de la EDAR del Barranco del Carraixet (Valencia, España).
Robles Martínez, Á. (2013). Modelling, simulation and control of the filtration process in a submerged anaerobic membrane bioreactor treating urban wastewater [Tesis doctoral]. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/34102
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Esse trabalho apresenta estudos, modelagem e análises de um sistema de bombeio centrífugo submerso (BCS), considerando as características dos principais componentes presentes neste sistema. As contribuições do trabalho estão na partida do BCS, como no desenvolvimento de soluções para mitigar alguns dos problemas observados, como por exemplo, os relacionados à qualidade de energia elétrica nos terminais do BCS. A modelagem de cada equipamento elétrico que compõe o BCS é apresentada no trabalho, destacando-se alguns dos aspectos operacionais relevantes que são considerados na operação. Foi feito um projeto para dimensionamento dos filtros passivos utilizados na atenuação das componentes harmônicas das tensões e correntes produzidas pelo sistema, além de auxiliar na regulação da tensão no ponto em que o BCS está conectado. Nas simulações realizadas, considerou-se um sistema de média tensão com um motor de indução trifásico em gaiola de esquilo de 3835HP que acoplado a uma bomba centrífuga possui um alto coeficiente de inércia. Com a inserção de modelos de atritos rotacionais para o torque do conjunto motor-bomba, pôde-se representar os efeitos que acontecem nos instantes iniciais da partida do sistema e avaliar o desempenho da estratégia de controle utilizada para o acionamento. Assim como ocorre nos sistemas reais que são alimentados por cabos submarinos de longo comprimento, utilizou-se um sistema de controle do sistema em malha aberta com uma metodologia para estimar e compensar a queda de tensão que ocorre entre os terminais do conversor e o terminal de entrada do motor elétrico. O trabalho apresenta ainda uma breve comparação entre o conversor fonte de tensão (VSC) de 2 níveis e o conversor de 3 níveis com neutro grampeado (NPC). Por fim, é analisada a situação onde a alimentação do BCS é desequilibrada devido à diferença de valores entre os parâmetros do cabo submarino.
This work shows studies, modelling and analyses of an electrical submersible pump system (ESP), considering the characteristics of key elements in this system. The contributions are in its start-up, as also in the development of solutions for mitigation of some observed problems, e.g., those related to power quality at the equipment terminals. The model for each electrical equipment inside the ESP is presented in this work and highlighted some of the pertinent operational aspects that is commonly considered on practical operation. A project is settled for sizing the passive filters to attenuate the harmonic components of the voltages and currents supplied by the grid, in addition to helping voltage regulation at ESP connection point. In the study cases, it was considered a medium voltage power system with a 3835HP three phase squirrel cage induction motor which is connected with a centrifugal pump that results in a high inertia coefficient. Rotational friction model is considered in the studies to characterize the effects that occur at the initial seconds of the start-up of the system and also to evaluate the performance of the implemented control strategy. In the same way that occurs in real systems that are supplied by downhole electric cables, it was considered an open-loop V/f control with a methodology to estimate and compensate the voltage drop that exists between the terminals of the converter and the motor input. This work also establishes a short comparison between a 2-level voltage source converter (VSC) and a 3-level neutral-point clamped (NPC) VSC. Finally, the system is analyzed through the occurrence of an unbalance of downhole electric cable parameters.

Patented by Joseph Monier in 1867, reinforced concrete became a highly successful material during the 20th century, capable of satisfying the most challenging demands of designers and engineers. However, even though its introduction in construction paved the way for a century of continuous technological innovation in the building industry, the mechanical behaviour of structures made with this material has not been fully understood for a long time, giving rise to a variety of structural problems of the buildings built in the first decades of the 20th century. At the roots of the problem there was not only the empirical conception of the structural calculations, but also the lack of development of standard concrete production technology and the poor attention paid to the choice of raw materials and their mixing methodology. Furthermore, the problem of reinforced concrete behavior to external chemical-physical degrading agents was not considered during most of the 20th century, due to the wrong assumption of “infinite durability” of this material. One and a half century after its invention, reinforced concrete is considered a cultural heritage material, being the structural core of the 20th century contemporary architecture. The characterization of this heterogeneous artifact has been for decades exclusive competence of structural engineers, but, over the last fifteen years, it has become one of the main fields of study of material scientists, due to its mineralogical, textural and chemical complexity and high susceptibility to the action of external chemical-physical degrading agents. Given the complexity of the material, a combined multidisciplinary approach, covering the engineering and material science fields, is necessary to obtain a full mechanical and microstructural characterization of reinforced concrete structures and, consequently, to plan and perform proper interventions with adequate restoration materials for the rehabilitation and structural improvement of this modern heritage. This research project is aimed at the multi-analytical characterization of cement conglomerates from five historical structures located in north-eastern Italy and built between the end of the 19th and the middle of the 20th century, paying attention to the determination of the original mix designs, to the study of their conservation state and to the development of novel medium invasive analytical techniques. The materials were first of all characterized according to a multi-analytical approach; in this part of the study, the classic petrographic characterization of the conglomerates following the guidelines of the American standard ASTM C856 was deeply integrated with the results obtained from mineralogical analyses by X-ray Powder Diffraction (XRPD) and from microstructural-microchemical analyses by Scanning Electron Microscopy and Energy-dispersive X-ray Microfluorescence (SEM-EDS). This integrated methodology of analysis allowed to broaden the spectrum of the analytical results obtained, fully characterizing the materials and their constituents in a broad dimensional, compositional and textural range. The data obtained, even though highly accurate, are still strictly qualitative, in particular as regards the determination of several parameters, fundamental for the reconstruction of the original mix designs (e.g. water/cement ratio, cement/aggregate ratio, granulometric distribution curve of the inert fraction). In this respect, several recent studies tested 2D digital image analysis procedures for the study of several concrete components, obtaining reliable and unbiased results. Nevertheless, despite the promising data obtained, the analytical procedures were never applied to the whole concrete constituents, mainly due to intrinsic limitations of the technique related both to the high polydispersity of the constituents and to the absence of clear colorimetric tracers to allow rapid and clear digital discriminations. Despite these problems, at the state of the art 2D digital image analysis is the only analytical technique theoretically capable of giving reliable, rapid and unbiased results on a such polydisperse material. Consequently, one of the main objectives of this research project consisted in the development of a valid and multiscale protocol of sample preparation, image acquisition, and analysis, in order to fully and quantitatively reconstruct mix designs of the studied historical concretes. The novel approach proved to be extremely reliable to fully characterize these heterogeneous and poorly standardized materials, and the analytical results obtained were successfully crosschecked with the ones obtained with the multi-analytical study. Finally, an accurate study of the conservation state and degradation phenomena acting on the materials was performed. The materials were studied according to a multi-analytical approach articulated in a preliminary petrographic study, integrated by profile XRPD analyses on the finer fractions of the materials and SEM-EDS analyses both on massive and thin section samples. The results highlighted the incidence of several alteration phenomena on the materials, strictly related to their compositional and textural characteristics and to the environmental conditions of exposure. Besides the identification of the occurrence of common forms of concrete alteration - namely carbonation, sulfate attack, chloride attack, alkali-aggregate reactions and soluble salts crystallization phenomena ˗ a novel type of degradation was observed and described for the first time in the concrete samples of the Ex-Agrimont Area, the synergic sulfate-phosphate attack. This form of alteration was thoroughly investigated through an extended profile multi-analytical approach consisting of a combination of optical microscopy, synchrotron-based micro-XRPD, SEM-EDS microanalyses, in situ thermal XRPD, simultaneous thermogravimetric and differential thermal analyses (TGA-DTA), inductively coupled plasma atomic emission spectroscopy (ICP-OES) and thermodynamic modeling. This form of alteration resulted to be strongly related to the interaction between sulfate-rich atmospheric multipollutants and phosphate-ammonia-rich solutions leached from the fertilizers production plant, and caused severe decalcification of the cement matrices and formation of secondary sulfates and phosphates according to a marked mineralogical and textural zoning, with stabilization of metastable phases thanks to the peculiar pH and concentration gradients developed in the materials. Furthermore, rare solid solution phases formed, undergoing partial dehydration phenomena related to the conditions of exposure.
Brevettato da Joseph Monier nel 1867, il conglomerato cementizio armato (comunemente definito calcestruzzo armato, o cemento armato) è diventato un materiale da costruzione di grandissimo successo nel corso del XX secolo, capace di soddisfare le richieste più impegnative di progettisti e ingegneri. Tuttavia, nonostante la sua introduzione e diffusione abbia spianato la strada a un secolo di continue innovazioni tecnologiche nell'ambito dell'industria delle costruzioni, il comportamento meccanico degli edifici costruiti con tale materiale non è stato compreso a pieno per lungo tempo, con conseguente incidenza di una serie di problemi strutturali interessanti gli edifici costruiti nei primi decenni del XX secolo. Alle radici del problema non vi era soltanto la concezione empirica dei calcoli strutturali, ma anche la mancanza di una tecnologia standardizzata di produzione del calcestruzzo e la scarsa attenzione posta nella scelta delle materie prime e delle strategie di miscelazione. Inoltre, le problematiche relative alla resistenza del conglomerato cementizio armato all'azione degradante di agenti chimico-fisici esterni non sono state considerate per gran parte del XX secolo, a causa dell'errata assunzione di "durabilità infinita" del materiale. Un secolo e mezzo dopo la sua invenzione, il cemento armato è al giorno d'oggi considerato un materiale di interesse culturale, costituendo il nucleo strutturale dell'architettura contemporanea. La caratterizzazione di questo materiale eterogeneo è stata per decenni di competenza esclusiva degli ingegneri strutturali, ma, nel corso degli ultimi quindici anni, è diventata una delle principali tematiche di studio degli scienziati dei materiali, a causa della complessità mineralogica, tessiturale e chimica del calcestruzzo e della sua suscettibilità all'azione di agenti alterativi esterni di natura chimico-fisica. Considerata la complessità del materiale, un approccio analitico combinato e multidisciplinare, comprendente campi sia ingegneristici sia della scienza dei materiali, risulta necessario al fine di ottenere una completa caratterizzazione meccanica e microstrutturale delle strutture in cemento armato e, conseguentemente, di progettare ed eseguire interventi di restauro con materiali adeguati per la riabilitazione e il miglioramento strutturale di questi moderni beni culturali. Tale progetto di ricerca è stato volto alla caratterizzazione multi-analitica di conglomerati cementizi appartenenti a cinque edifici storici in cemento armato, tutti localizzati nell’Italia nordorientale e costruiti tra la fine del XIX secolo e la metà del XX secolo, prestando particolare attenzione alla determinazione dei mix design originari, allo studio del loro stato di conservazione e allo sviluppo di tecniche analitiche innovative di natura mediamente distruttiva. I materiali sono stati anzitutto caratterizzati tramite un approccio multi-analitico; in questa parte dello studio, la classica caratterizzazione petrografica dei conglomerati secondo le linee guida dello standard americano ASTM C856 è stata integrata con i risultati ottenuti tramite analisi mineralogiche in diffrazione ai raggi X delle polveri (XRPD) e analisi microstrutturali e microchimiche in microscopia elettronica a scansione e microfluorescenza ai raggi X a dispersione di energia (SEM-EDS). La metodologia analitica integrata ha permesso un notevole allargamento dello spettro dei risultati ottenuti, consentendo una caratterizzazione completa dei materiali e dei loro costituenti in un ampio intervallo dimensionale, composizionale e tessiturale. I risultati ottenuti, sebbene altamente accurati, sono strettamente qualitativi, in particolare per quanto concerne la determinazione di una serie di parametri fondamentali per la ricostruzione dei mix design originari (quali i rapporti acqua/cemento e cemento/aggregato e la curva di distribuzione granulometrica degli inerti). A tal riguardo, diversi studi hanno recentemente testato procedure di analisi di immagine 2D per lo studio di componenti del calcestruzzo indurito, ottenendo risultati affidabili e oggettivi. Ciononostante, tali procedure analitiche non sono mai state applicate al sistema calcestruzzo nel suo insieme, a causa di limitazioni intrinseche delle tecniche di studio legate sia all'alto grado di polidispersione delle componenti del conglomerato cementizio, sia all'assenza di chiari traccianti colorimetrici in grado di consentire una rapida e chiara discriminazione digitale delle stesse. Al di là di tali problematiche, allo stato dell'arte l'analisi di immagine 2D risulta essere l'unica tecnica analitica in grado, almeno in via teorica, di fornire risultati rapidi, attendibili e oggettivi su un materiale caratterizzato da un grado di polidispersione così elevato. Conseguentemente, uno degli obbiettivi principali di questo progetto di ricerca è consistito nello sviluppo di un valido protocollo multiscala di preparazione dei campioni e acquisizione e analisi delle immagini per ricostruire completamente e quantitativamente i mix design dei calcestruzzi storici studiati. Tale approccio analitico innovativo si è dimostrato estremamente affidabile per l'ottenimento di una caratterizzazione completa di questi materiali eterogenei e poco standardizzati, e i risultati ottenuti sono stati confrontati con successo con quelli ottenuti tramite lo studio multi-analitico. Infine, è stato effettuato uno studio dettagliato dello stato di conservazione e dei fenomeni di degrado agenti sui materiali. I calcestruzzi sono stati studiati con un approccio multi-analitico articolato in uno studio petrografico preliminare, integrato da analisi XRPD di profilo della frazione fine dei materiali e da analisi SEM-EDS sia su campioni massivi che in sezione sottile. I risultati hanno evidenziato l'incidenza nei materiali di molteplici fenomeni di alterazione, strettamente correlati alle loro caratteristiche composizionali e tessiturali e alle condizioni ambientali di esposizione. Oltre all'individuazione di forme comuni di alterazione del calcestruzzo, quali la carbonatazione, l'attacco solfatico, l'attacco da cloruri, le reazioni alcali-aggregato e di ricristallizzazione di sali solubili, una nuova tipologia di degrado è stata per la prima volta osservata e studiata nei campioni di calcestruzzo dell'Area Ex-Agrimont, l'attacco sinergico solfatico-fosfatico. Questa forma di alterazione è stata investigata approfonditamente attraverso un approccio multi-analitico di profilo, consistente in una combinazione di microscopia ottica, micro-XRPD in luce di sincrotrone, microanalisi SEM-EDS, XRPD termica in situ, analisi termogravimetriche e termiche differenziali simultanee (TGA-DTA), spettroscopia di emissione atomica a plasma accoppiato induttivamente (ICP-OES) e modeling termodinamico. Tale forma di alterazione è risultata essere strettamente legata all'interazione tra inquinanti atmosferici ricchi in solfati e soluzioni ricche in fosfati e ioni ammonio rilasciati dall'impianto di produzione di fertilizzanti, e ha causato una grave decalcificazione delle matrici cementizie e la formazione di fosfati e solfati secondari secondo una marcata zonazione mineralogica e tessiturale, con associata stabilizzazione di fasi metastabili a causa dei particolari gradienti di pH e concentrazione degli inquinanti venutisi a stabilire all'interno dei materiali. Inoltre, si sono formate rare fasi in soluzione solida, le quali hanno successivamente subito fenomeni di parziale disidratazione correlati alle condizioni di esposizione.

Since the second half of the 20th century, an expansion of the forest in European mountain areas due to agricultural abandonment has been observed. The reduction of the agricultural intensity implies the disappearance of semi-natural alpine meadows and pastures of great ecological and aesthetic value. This thesis proposes a computational model, using P systems, to simulate the future agricultural landscape evolution in the Catalan Pyrenees and in the Stubai Valley, located in central Alps, for a period of 30 years. In these regions, three simulated scenarios have been established: (1) Continuation of the observed farming trends, or maintenance of the status quo, (2) significant and (3) strong stocking rate reductions. The results show how the traditional agricultural surfaces decrease in all simulated scenarios in both study areas. Therefore, it is important to apply new strategies to preserve these cultural surfaces and the multiple ecosystem services for future generations before they disappear definitively.
D'ençà de la segona meitat del segle XX s'ha observat una expansió del bosc a les zones de muntanya europees, originada per l'abandonament de l'agricultura. La reducció de la intensitat agrícola comporta la desaparició de prats i pastures alpins seminaturals de gran valor ecològic i estètic. Aquesta tesi proposa un model computacional utilitzant P sistemes per simular l'evolució futura del paisatge agrícola als Pirineus catalans i a la Vall de Stubai, situada als Alps centrals, durant un període de 30 anys. En aquestes regions s'han establert tres escenaris a simular: (1) continuació de la tendència ramadera observada, o manteniment del statu quo, (2) reducció significativa i (3) molt forta de la càrrega ramadera. Els resultats obtinguts mostren com la superfície agrícola tradicional es redueix en tots els escenaris simulats en ambdues àrees d'estudi. Per tant, és important aplicar noves estratègies per preservar aquestes superfícies culturals i els múltiples serveis de l'ecosistema per a les futures generacions, abans que desapareguin definitivament.
Desde la segunda mitad del siglo XX se ha observado un expansión del bosque en las zonas de montaña europeas, originada por el abandono de la agricultura. La reducción de la intensidad agrícola implica la desaparición de prados y pastos alpinos seminaturales de gran valor ecológico y estético. Esta tesis propone un modelo computacional utilizando P sistemas para simular la evolución futura del paisaje agrícola en los Pirineos catalanes y en el Valle de Stubai, situado en los Alpes centrales, durante un periodo de 30 años. En estas regiones se han establecido tres escenarios a simular: (1) continuación de la tendencia ganadera observada, o mantenimiento del statu quo, (2) reducción significativa y (3) muy fuerte de la carga ganadera. Los resultados obtenidos muestran como la superficie agrícola tradicional se reduce en todos los escenarios simulados en las dos áreas de estudio. Por lo tanto, es importante aplicar nuevas estrategias para preservar estas superficies culturales y los múltiples servicios del ecosistema para las futuras generaciones, antes de que desaparezcan definitivamente.

SCADA-system (Supervisory Control and Data Acquisition) har under de senaste decennierna använts i stor utsträckning, med utmärkta resultat för nätverksdrift och -förvaltning. Kunder ställer emellertid krav på att SCADA-system ska kunna integrera externa komponenter för att möjliggöra utveckling av befintliga och nya affärsprocesser. Det innebär att dessa system utvecklas från en monolitisk infrastruktur till en löst kopplad och flexibel arkitektur. Således har nya behov uppstått för att förbättra systemets interoperabilitet, minska komplexiteten och förbättra underhållet. Föreliggande masterprojekt presenterar ett ramverk för att förutsäga systems interoperabilitetet (IPF); ett ramverk som stöder arkitekturprocessen under de tidiga stadierna av produktutveckling. Vidare har arbetet undersökt några alternativa arkitekturer, vilka har modellerats och verifierats med hjälp av ovannämnda ramverk. En första konceptuell arkitektur har utvecklats för att förbättra interoperabiliteten hos interna system, för att reducera kopplingen mellan det grundläggande SCADA-systemet och Energy Management-systemet (EMS). Därefter genererades en andra arkitektur som möjliggör integration av externa komponenter för att främja den externa interoperabiliteten. Resultat visar att de föreslagna arkitekturerna är korrekta (enligt IPF) och systemets driftskompatibilitet förbättras. Vidare förefaller den slutligt föreslagna lösningen vara mindre komplex än den nuvarande arkitekturen på lång sikt, men det skulle behövas en större insats och väsentliga förändringar för att uppgradera systemarkitekturen.
SCADA (Supervisory Control and Data Acquisition) systems have been widely used during the last decades delivering excellent results for the power network operation and management. However, some current customer requirements are for SCADA systems to integrate external components in order to perform advanced power network studies and develop both existing and new business processes. This novel viewpoint will make these systems evolve from a monolithic infrastructure towards a loosely coupled and flexible architecture. Hence, new needs have arisen with the aim of improving the system interoperability, reducing the complexity and enhancing the maintainability. This master´s thesis project presents an Interoperability Prediction Framework (IPF), that supports the architecture design process during the early stages of product development. In addition, this work has also investigated some alternative architectures, which have been modelled and verified using the previously mentioned framework. A first conceptual architecture has been designed to improve the internal system interoperability, reducing the coupling between the basic SCADA and the Energy Management System (EMS). Later, a second architecture that allows the integration of external components has been introduced to promote the external interoperability. Results show that the proposed architectures are correct (according to the IPF) and the interoperability of the system is improved. Furthermore, initial conclusions suggest that the final proposed solution would be less complex than the current architecture in the long term, although a large effort and substantial changes would be needed to upgrade the system architecture.

In questo elaborato vengono presentati i risultati ottenuti dallo studio della cinematica dell'ammasso globulare NGC 6569. L'ammasso è stato analizzato per ricercare la presenza di un eventuale buco nero di massa intermedia (IMBH) nel suo centro. Gli IMBH sono una classe di oggetti la cui esistenza non è ancora stata provata osservativamente, con masse comprese tra il migliaio e le centinaia di migliaia di masse solari e che teoricamente sarebbero in grado di spiegare diversi problemi astrofisici aperti. Una delle prove più convincenti della possibile esistenza di un IMBH all'interno di un ammasso globulare è la presenza di una cuspide centrale nel profilo di dispersione delle velocità. Per poter ottenere questo profilo è necessario determinare le velocità radiali (RV) delle singole stelle appartenenti all'ammasso. I dati analizzati in questo lavoro sono stati raccolti tramite osservazioni SINFONI, uno spettrografo a campo integrale munito di ottiche adattive dell’ESO-VLT e sono relativi a 8 campi di vista con dimensioni di 8"x 8" entro un raggio di 15" dal centro dell'ammasso. Attraverso l'analisi spettroscopica di spettri di buona qualità, è stato possibile ottenere le misure di RV per un campione di 38 stelle. Al fine di poter determinare il profilo di dispersione di velocità dell'ammasso lungo tutta la sua estensione radiale, le misure di velocità SINFONI sono state combinate con un catalogo di RV relativo alle regioni più esterne, ottenuto tramite osservazioni FLAMES (ESO-VLT). Il profilo risultante è ben descritto da un modello di King a core piatto, portando ad escludere la presenza di un IMBH con massa pari o superiore a 10000 masse solari.

In the last decades and due to the Water Framework Directive implementation, the urban wastewater cycle management has become more complex. The concept of integrated urban wastewater system management is introduced, and it becomes necessary to consider some new data as the sewer system characteristics or the receiving body. In this sense, environmental decision support systems (EDSS) are very useful and powerful tools to support during the decision making process. A new EDSS for the integrated urban wastewater system management has been developed integrating data from several sources (bibliographic, theoretical or historical) and a real case-based virtual system able to perform simulations. Results demonstrate the benefits of using this kind of systems in comparison with a standard approach, which do not use the expert knowledge and encourages continuing with this research in order to improve the quality and efficiency of this type of EDSSs
En les darreres dècades, i degut a la implementació de la Directiva Marc de l’Aigua, la gestió del cicle urbà de l’aigua ha esdevingut més complexa. S’introdueix el concepte de gestió integrada de conca, i és necessari considerar certa informació, com les característiques de la xarxa de clavegueram o del medi receptor. D’aquesta manera, els sistemes de suport a la decisió ambiental (EDSS) són eines potentíssimes que faciliten la presa de decisions en aquest camp. S’ha desenvolupat un nou EDSS per a la gestió integrada de conca que utilitza una base sòlida de coneixement expert, integrant informació de diverses fonts (bibliogràfiques, teòriques o històriques) i dos sistemes virtuals basats en dades reals sobre els quals és possible realitzar simulacions. Els resultats demostren que aquest sistema presenta beneficis importants respecte a una gestió estàndard sense sistema expert, i esperona a prosseguir amb la recerca i el desenvolupament per a millorar-lo

The marine industry has increased its adoption of pure-electric, diesel-electric, and other non-traditional propulsion architectures to reduce ship emissions and fuel consumption. While these technologies can improve performance, the design of a propulsion system becomes challenging, given that no single technology is superior across all vessel types. Furthermore, even identical ships with different operating patterns may be better suited to different propulsion technologies. Addressing this problem, previous research has shown that if key elements of a vessel's operational pro file are known, simulation and optimization techniques can be employed to evaluate multiple propulsion architectures and result in a better propulsion system design and energy management strategy for a given vessel. While these studies have demonstrated the performance improvements that can be achieved from optimizing clean marine propulsion systems, they rely on vessel operational profiles obtained through physical measurement from existing ships. From a practical point of view, the optimization of a vessel's propulsion system needs to occur prior to a vessel's construction and thus precludes physical measurement. To this end, this thesis introduces a marine simulation platform for producing vessel operational profiles which enable propulsion system optimization during the ship design process. Core subsystem modules are constructed for simulating ship motions in 3 degrees of freedom and result in operational profile time-series, including propulsion power. Data is acquired from a benchmark vessel to validate the simulation. Results show the proposed approach strikes a balance between speed, accuracy, and complexity compared with other available tools.
Graduate

For the study of homogeneous catalytic reaction mechanisms, the ideal technique would be capable of identifying and measuring in real time the abundances of all components of the reaction mixture, including reactants, products, byproducts, intermediates, and catalyst resting states. This thesis details the development of methodologies designed to transform electrospray ionization mass spectrometry into just such a tool. Species of interests must be charged otherwise invisible in ESI-MS. Therefore, charge-tagged aryl iodide ([4-I-C6H4CH2PPh3]+[Br]-) and a terminal alkyne ([para-(HCC)C6H4CH2PPh3]+[Br]-) were synthesized as the ESI-active substrates for the homogeneous catalysis study. A method named PSI (pressurized sample infusion) was developed to introduce the air and moisture sensitive reaction mixtures to the ESI-MS. The analytical aspects of the method were investigated and optimized. Applicability of the technique was demonstrated through several organic and organometallic mechanism investigations. The above developments were employed to the detailed study of the copper-free Sonogashira (Heck alkynylation) reaction and the hydrodehalogenation of the charged-tag aryl iodide. Simultaneous monitoring of the charged substrate, products and intermediates in the copper-free Sonogashira reaction by PSI-ESI-MS provided rich information about the kinetic and mechanism of this reaction. Kinetic isotope effect study shows a remarkable inverse kinetic isotope effect which is completely unexpected. Numerical models were constructed to simulate the mechanistic observation and to extract the rate constant of each step in the proposed mechanism cycle. The same methodology (PSI technique) was used to the study of the hydrodehalogenation reaction. Key intermediates were detected under the typical reaction conditions. Kinetic isotope effect study was performed in CH3OD and CD3OD. A primary KIE was observed in both deuterated solvents. A revised mechanism cycle was suggested for this reaction based on KIE results, numerical modelling and other experiments. In the proposed cycle deprotonation of methanol occurs on the palladium metal centre instead of the conventional in solution deprotonation (off metal deprotonation). The mechanism of the ligand substitution of charged-tag of a palladium aryl iodide [Pd(TMEDA)(Ar)(I)]+ (Ar = [C6H4CH2PPh3]+[PF6]-) complex against PPh3 was studied in methanol by PSI-ESI-MS. Results revealed that the pathway proceeds quite differently to what had been assumed by others; there was a very fast displacement of [I]– by PPh3 to form [Pd(TMEDA)(Ar)(PPh3)]2+ , followed by a much slower displacement of TMEDA and recoordination of [I]– to form the product [Pd(PPh3)2ArI]+. We successfully integrated UV/Vis spectroscopy, as a complementary method with ESI-MS to shed light into the systems where ESI-MS only is unable to provide a full assignment to homogenous catalysis. The combination of the two fast and sensitive techniques provides a unique opportunity to study the composition of the organometallic reaction mixtures over time.
Graduate
0486
zohrabahmadi@gmail.com

Fracture and fracture network modelling is a multi-disciplinary research area. Although the literature in general is significant, many research challenges remain. The complex geometry and topology of realistic fracture networks largely determine the static and dynamic mechanical properties of rock. In applications to hot dry rock geothermal reservoirs it is not possible to observe or measure fractures directly on any scale and the only data available are indirect measurements, such as seismic activity generated by hydraulic fracture stimulation. The lack of direct data and the complexities of the fracture characteristics make fracture network prediction and modelling in these applications very difficult. The ultimate purpose of the fracture and fracture network models is to evaluate the response of the fracture system to stress regimes and fluid flow. As understanding of the effective factors in the geometrical modelling of fractures and consequently topological properties of fracture networks increases, more accurate and hence more reliable results can be achieved from associated analyses. For flow modelling in geothermal reservoirs, the critical component of a fracture model is the connectivity of the fractures as this determines the technical feasibility of heat production and is the single most significant factor in converting a heat resource to a reserve. The ability to model this component effectively and to understand the associated system is severely constrained by the lack of direct data. In simulations, the connectivity of a fracture network can be controlled to a limited extent by adjusting the fracture and fracture network parameters (e.g., locations, orientations) of the defining distribution functions. In practical applications connectivity is a response of the system not a variable. It is essential to pursue modelling methods that maximise the extraction of information from the available data so as to achieve the highest possible accuracy in the modelling. Although the evaluation of fracture connectivity is an active research area, widely reported in the literature, almost all connectivity measures are based on degraded representations of the fracture network i.e., lattice-based. The loss of fracture connectivity information caused by using discrete representations is significant even when very high resolutions (assuming they are feasible) are used. This is basically due to the fact that the aperture dimensions of fractures are several magnitudes smaller than their lengths. If discretisation is necessary, then a better approach would be to retain all connectivity information between fractures, i.e. for connectivity information to remain invariant to the resolution of the discretisation. Such a method would provide more reliable evaluation of connectivity. This thesis covers the modelling of fracture networks, the characterisation (particularly connectivity) of fracture networks and applications.
Thesis (Ph.D.) -- University of Adelaide, School of Civil, Environmental and Mining Engineering, 2014

Low English proficiency among secondary school students is a major concern in Malaysia, especially in the context of the Malaysian Independent Chinese Secondary Schools since Malaysian students who have spent eleven to thirteen years studying the English language are still not able to master it upon completing secondary schooling. In addition, a significant number of Malaysian graduates are unemployed, and even those who are employed receive complaints from the employers due to their limited English proficiency. It is argued that student-, teacher- and school-level factors may impact on students’ English proficiency. A significant amount of research related to these factors has been conducted, ranging from finding universal trends to identifying differences. These studies have examined the relationships between students’ characteristics, attitudes and motivation, anxiety and self-efficacy as well as conceptions of and approaches to learning; teachers’ characteristics and approaches to teaching; as well as schools’ demographic variables such as instructional time, student-teacher ratio, resources and facilities as well as curriculum and assessment. Researchers have shown that these factors may impact on students’ English proficiency in a single-level model. However, numerous scholars have also argued that these factors may interact with each other and thus focussing on just a single level may not be sufficient to explain the complexity of English language learning and teaching. In addition, limited research has been conducted in the Malaysian context, especially in the Malaysian Independent Chinese Secondary Schools. This research study examines the student-, teacher- and school-level factors, their interrelationships and their impact on students’ English as a second language proficiency. A quantitative research design was used including questionnaires and assessment checklist to collect data from the respondents. The respondents in this study involved the Malaysian Independent Chinese Secondary Schools located at the urban areas in Kuala Lumpur, Selangor, Perak and Penang, the Senior 1 English language teachers, and all Senior 1 students who were taught by these teachers. A number of scales and demographic items related to student-, teacher- and school-level factors were administered for the purpose of this study. All scales except the demographic items employed in this study were validated, calibrated and verified using the Confirmatory Factor Analysis and Rasch Analysis. In addition, as many teachers or raters from different schools and classes were involved in rating students’ English language proficiency, their scores were adjusted by modelling rater judgement through the many facets Rasch analysis. The raw scores obtained from the responses in all scales were anchored to obtain the Weighted Likelihood Estimates for use in subsequent analyses which included the analyses for the student- and teacher-level models as well as the hierarchical linear model. The Structural Equation Modelling approach was employed to examine the student- and teacher-level models. For the student-level model, all scales or variables and demographic items were examined with regards to their interrelationships and how they influenced students’ English language proficiency. For the teacher-level model, the interrelationships of the variables and demographic items were examined. In addition, as data collected were of a hierarchical structure, the relationships among the nested variables in school-, teacher- and student-levels, how these variables influenced students’ English language proficiency, and the cross-level interactions of these variables were examined in the hierarchical linear model. Results of the analyses show that student-, teacher- and school-level variables influence students’ English language proficiency. A significant finding from this study is that students’ motivation, attentiveness in class, the use of deep and surface learning approaches as well as the student-focused teaching approaches and the number of students in schools directly influence students’ English language proficiency. The findings further indicate that students who have higher levels of motivation and attentiveness as well as who use deep learning approaches more tend to have higher English proficiency levels. On the other hand, students who use surface learning approaches more tend to have lower English proficiency levels. The findings also indicate that the more teachers use student-focused teaching approaches and the more students schools have, the more likely students achieve at a higher level in English. Furthermore, while the number of story books in the library moderates the effect of students’ attentiveness on their English proficiency negatively, the emphasis in reading skills moderates positively the effect of student-focused teaching approaches on students’ English proficiency. In addition, teachers’ formal professional development activities positively moderate the effect of students’ motivation on students’ English proficiency. Moreover, multiple interrelationships among the student-level variables are identified in the student-level model. Although not as complicated as the student-level model, the results from the teacher-level model also indicate the interrelationships among the teacher-level variables. Thus, the results of this study support the idea that student-, teacher- and school-level factors interact with each other and impact on students’ English language proficiency. This research is particularly meaningful with regards to its contribution to the theoretical, practical and methodological implications in the English language learning and teaching. These findings suggest new courses of action for designing a suitable curriculum for English learners, strategies for teaching and improving teaching skills as well as a better environment for the learning and teaching of English in the Malaysian Independent Chinese Secondary Schools. The student-, teacher- and school-level factors need to be taken into considerations when one aims to improve students’ English language proficiency.
Thesis (Ph.D.) -- University of Adelaide, School of Education, 2016.

The concern of increasing energy consumption with depleting energy resources is ever growing. Though the solution to this problem lies in part in renewable energies, it is becoming increasingly clear that sustainable building design also plays a critical role. Controlling solar gain, for example, can greatly reduce the cooling energy consumption and lowering the peak cooling load. Having the ability to model these effects can have a substantial impact on the sizing of equipment and further reduce operational costs of a building. As a result, renewed interest has been invested by researchers and industry to promote the development and use of building simulation tools to aid in the design process. Efforts at the University of Waterloo’s Advanced Glazing Systems Laboratory have resulted in a set of shading device models, with emphasis on generality and computational efficiency, tailored for use in building simulation. These models have been validated with measurements at the component level and with measurements performed at the National Solar Test Facility (NSTF) on a full scale window system, giving confidence to model validity. Continued research has resulted in the integration of these shading device models into ESP-r via the Complex Fenestration Construction (CFC) module, capable of modelling multi-layer glazing and shading layer systems and greatly improving the value of ESP-r as a design tool. The objective of the current research was to implement shading device models for roller blinds, pleated drapes and insect screens to the CFC module. These would be in addition to the venetian blind model which had previously been established. A Monte-Carlo ray tracing analysis of pleated drape geometry and incident angle dependent fabric characteristics gave further confidence to the view factor or net reduction method used by the implemented models. On model implementation, a preliminary comparison was performed between a high-slat angle venetian blind, a roller drape and drapery fabric, all given the same material properties, with similar results. Further comparison was then performed using EnergyPlus shading device models to establish further confidence in the functionality of the models. Though there was some discrepancy between the results, primarily due to convective models, good agreement was found, and the effect of the shading device models on building performance was demonstrated. The successful implementation of roller blind, pleated drape and insect screen shading models to the CFC module in ESP-r has been demonstrated in the current research. It should also be noted that the convective models for indoor shading attachments is a worthwhile topic for further research, at which point it would then be beneficial to conduct further empirical validation on the ESP-r simulation.

Indiana University-Purdue University Indianapolis (IUPUI)
In a multifidelity structural design process, depending on the required analysis, different levels of structural models are needed. Within the aerospace design, analysis and optimization community, there is an increasing demand for automatic generation of parametric feature tree (build recipe) attributed multidisciplinary models. Currently, this is mainly done by creating separate models for different disciplines such as mid-surface model for aeroelasticity, outer-mold line for aerodynamics and CFD, and built-up element model for structural analysis. Since all of these models are built independently, any changes in design parameters require updates on all the models which is inefficient, time-consuming and prone to deficiencies. In this research, Engineering Sketch Pad (ESP) is used to create attribution and maintain consistency between structural models with different fidelity levels. It provides the user with the ability to interact with a configuration by building and/or modifying the design parameters and feature tree that define the configuration. ESP is based an open-source constructive solid modeler, named OpenCSM, which is built upon the OpenCASCADE geometry kernel and the EGADS geometry generation system. The use of OpenCSM as part of the AFRL’s CAPS project on Computational Aircraft Prototype Syntheses for automatic commercial and fighter jet models is demonstrated. The rapid generation of parametric aircraft structural models proposed and developed in this work will benefit the aerospace industry with coming up with efficient, fast and robust multidisciplinary design standardization of aircraft structures. Metallic aircraft wings are usually not optimized to their fullest potential due to shortage of development time. With roughly \$1000 worth of potential fuel savings per pound of weight reduction over the operational life of an aircraft, airlines are trying to minimize the weight of aircraft structures. A stiffness based strategy is used to map the nodal data of the lower-order fidelity structural models onto the higher-order ones. A simple multi-fidelity analysis process for a parametric wing is used to demonstrate the advantage of the approach. The loads on the wing are applied from a stick model as is done in the industry. C program is created to connect the parametric design software ESP, analysis software Nastran, load file and design configuration file in CSV format. This problem gets compounded when it comes to optimization of composite wings. In this study, a multi-level optimization strategy to optimize the weight of a composite transport aircraft wing is proposed. The part is assumed to initially have some arbitrary number of composite super plies. Super plies are a concept consisting of a set of plies all arranged in the same direction. The thickness and orientation angles of the super plies are optimized. Then, each ply undergoes topometry optimization to obtain the areas of each super ply taking the least load so that it could be cut and removed. Each of the super plies are then optimized for the thickness and orientation angles of the sub plies. The work presented on this paper is part of a project done for Air Force Research Laboratory (AFRL) connecting the parametric geometry modeler (ESP) with the finite element solver (Nastran).

Dissertação de Mestrado em Engenharia e Gestão de Sistemas de Informação
Dado que as organizações se regem por processos de negócio, é emergente a necessidade de o desenvolvimento do sistema de informação de uma organização seja direccionado para suportar esses processos. Durante um processo de desenvolvimento de sistemas de informação são conhecidas várias abordagens e metodologias com o objectivo de este seja obtido com cada vez maior acréscimo de qualidade. Essa qualidade deve-se reflectir na definição dos processos do sistema de informação e deve requerer uma metodologia que possua tarefas bem definidas e automatizadas. Uma metodologia possível, a Business Implementation Methodology (BIM), propõe transformações dos processos de negócio de forma automatizada para que a implementação dos processos em software consuma menor esforço e menores custos. As quatro fases da metodologia são percorridas desde a definição inicial dos processos de negócio até ao sistema de informação final. O que distingue nesta fase das outras metodologias é a proposta de utilizar modelos de referência de processos. Dado o contexto, sugere-se a utilização de linguagens de modelação de processos para representação gráfica dos processos de negócio. Para obtenção do sistema de informação na última fase da metodologia seguida, é proposta a utilização do Model-Driven Architecture (MDA). A transformação de um modelo de processos de negócio que seja um Platform Independent Model (PIM) para um modelo que seja um Platform Specific Model (PSM) permitirá a obtenção da implementação do modelo de processos em software. O resultado da transformação será um modelo composto pelo processo de negócio em BPEL e pela devida integração de aplicações realizadas através do uso de um Enterprise Service Bus (ESB).
Due the fact that organisations rule their business by business processes, it is emerging the need that development of the information system should be oriented to support those processes. During the process of an information system development many approaches are known so it can be achieved with an increase of quality. This quality must be reflected in the definition of the information system’s business processes and it requires a methodology that has well defined and automated tasks. A possible methodology, the Business Implementation Methodology (BIM), proposes transformations of business processes in an automated way so software implementation of the processes are less effort consuming. The four methodology phases are executed since the initial definition of the business process to the final information system. What distinguishes this methodology from other business implementation methodologies in these initial phases is the use of process reference models proposal. In the context, it is suggested the use of business process modelling languages for visual representation of business processes. For obtaining the information system in the last phase of the methodology, it is proposed the use of OMG’s Model-Driven Architecture (MDA). The transformation of a process framework that is a Platform Independent Model (PIM) to a Platform Specific Model (PSM) will allow obtaining software implementation. The result of the transformation will be a model composed by the business process in BPEL and the integration of applications through the use of an Enterprise Service Bus (ESB).