The ever-increasing levels of greenhouse gas emissions has led to the scientific community starting to explore the viability of electrical aircraft system, with the most prominent research and product development for hybrid electric system, which forms the transition phase from combustion to fully electric aircrafts. The primary objective of this thesis is to find solutions towards thermal management of the electrical components of a hybrid electric aircraft propulsion system, which generate a significant amount of heat while operating at heavy load conditions required to propel an aircraft. In view of these objectives a micro channel cold plate liquid cooling system, has been dynamically modelled using a combination of lumped parameter and thermal resistance methods of heat transfer analysis. The study investigates the prospects of using Mobil Jet Oil II, typically used as an aircraft lubricant as a coolant for the thermal management system. The primary components of this model are lithium ion battery, DC-AC inverter, permanent magnet motor, cross flow finned micro channel heat exchanger, centrifugal pump and ducts. The electrical components have been dimensioned according to energy storage and load requirements considering their efficiencies and gravimetric power/energy. The system has been simulated and analyzed under different scenarios considering the coolant inlet temperature, air temperature across the heat exchanger and on two-time horizons. Analysis has been done to study the dynamic trends of the component temperature and the coolant at different stages of the system. The scope of the study includes an evaluation of the added weight of the thermal management system under different time horizons and their comparison with results from a reference study. From the simulation results it can be concluded that Mobil Jet Oil II is a promising option as a coolant and therefore its use as a common fluid for gas turbine lubrication and as coolant, will benefit the aircraft as now no extra coolant reservoir is required, allowing reduction in weight carried by the aircraft.

As buildings have become more energy efficient, the energy demand for preparation of domestic hot water stands out as an increasing part of the operational cost and carbon footprint of a building. Most of the heat in the water is used for a short time and then discharged to the main sewer line. Clarion Hotel Stockholm is an example of such a building, with many showers, bathtubs and a spa. The hotel business is growing around the world and its customers demand comfortable stays. A parallel trend is a more environmentally aware tourism and business travel. Hotels show a great potential for energy savings, while still offering comfortable accommodation. In this master's thesis a case study evaluates the possibilities for heat recovery from the wastewater of Clarion Hotel Stockholm. Three types of heat exchangers were modelled in the system dynamic modelling environment STELLA: a horizontal, a vertical and a shower heat exchanger. Recovered heat was used for pre-heating of the incoming water for domestic hot water preparation. The flows of heat through the hotel's tap water and wastewater systems were schematically modelled using system dynamic modelling, which provides a foundation for the development of mathematical models and further research into the area. The first results point to possible reductions of the heating demand for domestic hot water preparation at Clarion Hotel Stockholm.

Bien que la France soit reconnue indemne de tuberculose bovine (TB) par l’Union Européenne depuis 2001, une centaine de nouveaux foyers sont déclarés chaque année. Deux des principaux mécanismes de propagation de l’infection entre troupeaux bovins sont l’introduction d’animaux infectés et les contacts au pâturage. L’objectif de cette thèse a été de quantifier les rôles respectifs des échanges commerciaux de bovins et des contacts au pâturage « par-dessus la clôture » dans la circulation de la TB en France entre 2005 et 2014. Pour cela, nous avons combiné des méthodes d’analyse de réseaux sociaux et de modélisation dynamique. Nos analyses ont montré que les contacts par le commerce étaient une origine probable pour 12% [5 - 18] des infections déclarées en France entre 2005 et 2014, contre 73% [68 - 78] pour la transmission locale. Cependant, nous avons pu observer que les contacts par le commerce permettaient à l’infection de coloniser de nouvelles zones. Puis nous nous sommes intéressés au risque structurel du réseau du pâturage. À partir d’une exploitation donnée, il était possible d’atteindre quasiment toutes les autres exploitations du territoire métropolitain. Il semble donc facile pour l’agent de la TB de se propager par les contacts de voisinage au pâturage. Enfin, afin de reconstituer la propagation de la TB en France entre 2005 et 2014, nous avons développé un modèle dynamique stochastique individu-centré, dirigé par les données et avec un pas de temps mensuel. Ce modèle reproduit une dynamique intra- et inter-élevages de l’infection, avec une transmission de l’infection entre élevages par le commerce et au pâturage. Il a permis de confirmer la facilité de propagation de l’infection via les contacts au pâturage. En conclusion, les mécanismes de propagation de la TB sont complémentaires : le commerce permet une diffusion sur de longues distances et le pâturage facilite la propagation locale. Le dispositif de lutte contre la tuberculose bovine doit donc s’appuyer combiner les mesures de contrôle afin de cibler plusieurs mécanismes de propagation. / Although France was declared free of bovine Tuberculosis (bTB) by the European Union in 2001, a hundred of outbreaks are reported every year. Cattle movements and contacts on pastures are considered the main between-herd transmission routes of bTB. The aim of this work was to quantify the respective roles of live cattle trade and “over the fence” contacts on pastures in the spread of bTB in France between 2005 and 2014, using social network analysis and dynamic modelling. Results showed that cattle movements may be the origin of 12% [5 - 18] of the French outbreaks between 2005 and 2014, versus 73% [68 - 78] due to the transmission on pasture. However, cattle movements appeared to allow the introduction of the bacteria into new areas. In a second step, the structural risk resulting from the French pasture network was studied. Almost all of the premises owning pastures were mutually connected by pastures neighbourhood relationships, on the territory. Thus, the spatial configuration of pastures appeared favourable to the spread of bTB in France. Finally, to mimic the spread of the infection in France between 2005 and 2014, a stochastic individual-based model was developed. It was driven by the data with a monthly time step. This model reproduced the within- and between-herd dynamic, with a between-herd transmission due to cattle movements and contacts on pastures. The easy spread of the bacteria through the network of French pastures was confirmed using the model. In conclusion, cattle movements and contacts on pastures are complementary paths for bTB spread: cattle movements allow the long-range spread, whereas contacts on pasture make easier the short-range spread. Hence, control programs must target several routes of transmission to be able to eradicate bTB.

En France, pays officiellement indemne de tuberculose bovine depuis 2001, l’infection persiste dans certaines zones, dont les Pyrénées-Atlantiques-Landes, où les niveaux d’infection observés chez les bovins et les blaireaux font craindre un fonctionnement particulier de ce système multi-hôtes pour Mycobacterium bovis, agent de la tuberculose bovine. L’objectif de cette thèse a été de mieux comprendre les mécanismes de transmission de M. bovis au sein du système bovins-blaireaux dans cette zone. L’analyse statistique du risque d’infection localement concomitante chez les blaireaux et les bovins a montré l’importance de variables environnementales liées à la survie de la bactérie dans le sol, telles que le microrelief et le pourcentage de sable dans le sol de surface, ainsi que celle de variables associées aux mouvements des blaireaux. L’analyse du réseau de contacts entre élevages bovins, incluant des contacts directs liés au commerce ou au voisinage au pâturage et des contacts indirects induits par un voisinage avec des domaines vitaux de blaireaux, a montré l’aspect multifactoriel de la transmission de M. bovis entre élevages. Enfin, la modélisation dynamique de la transmission de M. bovis dans le système bovins-blaireaux a suggéré une interface asymétrique entre blaireaux et bovins dans notre zone d’étude, les terriers étant pour la plupart infectés suite à l’exposition des blaireaux à une pâture dont le sol était contaminé par un bovin infectieux, alors que les modes de contamination des élevages se partageaient entre l’exposition des bovins à un élevage infectieux voisin de pâture, et la contamination de ces pâtures par un blaireau infectieux. La validation du modèle dynamique proposé doit encore être poursuivie. L’ensemble de nos résultats permet cependant de conclure à l’importance de prendre en compte tous les mécanismes de propagation dans la lutte contre la tuberculose bovine dans la zone. Le modèle développé est destiné à devenir un outil permettant de préciser les rôles épidémiologiques des bovins et des blaireaux et de simuler différentes stratégies de contrôle, pouvant inclure la vaccination des blaireaux. / France is officially free from bovine tuberculosis since 2001, but this infection is still persistent in some areas, including Pyrénées-Atlantiques - Landes. There, both cattle and badgers were found infected, suggesting that this multi-host system might have a particular functioning regarding Mycobacterium bovis (the main agent for bovine tuberculosis in France) transmission. The objective of the thesis was to better understand M. bovis transmission mechanisms throughout the badger-cattle system in this area. The statistical analysis of the local risk of the badger and cattle concomitant infection showed the importance of environmental variables such as microrelief and sand proportion of the topsoil as well as variables depicting badger movements. The analysis of the contact network between farms (that included direct contacts due to trade and to neighbouring pastures and indirect contacts due to the vicinity with badger home ranges) showed a multifactorial aspect of the transmission between farms in our study area. Finally, the dynamic modelling of M. bovis transmission throughout the badger-cattle system suggested an asymmetric interface where the infection of badgers due to soil contaminated by infected cattle was predominant, whereas, for the infection of cattle, the soil contaminated by infected badgers had a similar importance as the presence of infectious cattle on the neighbouring pastures. Our dynamic model validation should be continued. Nevertheless, our whole range of results underlined the importance of targeting all transmission mechanisms for infection control. The model we proposed is a tool designated to assess both cattle and badgers’ epidemiological roles as well as to simulate different control strategies, that could include badgers’ vaccination.

A complete chain of analysis and synthesis system identification tools for detectability assessment and adaptive identification of parameters with physical interpretation that can be found commonly in control-oriented powertrain models is presented. This research is motivated from the fact that future powertrain control and monitoring systems will depend increasingly on physically oriented system models to reduce the complexity of existing control strategies and open the road to new environmentally friendly technologies. At the outset of this study a physics-based control-oriented dynamic model of a complete transient engine testing facility, consisting of a single cylinder engine, an alternating current dynamometer and a coupling shaft unit, is developed to investigate the functional relationships of the inputs, outputs and parameters of the system. Having understood these, algorithms for identifiability analysis and adaptive identification of parameters with physical interpretation are proposed. The efficacy of the recommended algorithms is illustrated with three novel practical applications. These are, the development of an on-line health monitoring system for engine dynamometer coupling shafts based on recursive estimation of shaft’s physical parameters, the sensitivity analysis and adaptive identification of engine friction parameters, and the non-linear recursive parameter estimation with parameter estimability analysis of physical and semi-physical cyclic engine torque model parameters. The findings of this research suggest that the combination of physics-based control oriented models with adaptive identification algorithms can lead to the development of component-based diagnosis and control strategies. Ultimately, this work contributes in the area of on-line fault diagnosis, fault tolerant and adaptive control for vehicular systems.

The data-driven models used for the design of powertrain controllers are typically based on the data obtained from steady-state experiments. However, they are only valid under stable conditions and do not provide any information on the dynamic behaviour of the system. In order to capture this behaviour, dynamic modelling techniques are intensively studied to generate alternative solutions for engine mapping and calibration problem, aiming to address the need to increase productivity (reduce development time) and to develop better models for the actual behaviour of the engine under real-world conditions. In this thesis, a dynamic modelling approach is presented undertaken for the prediction of NOx emissions for a 2.0 litre Diesel engine, based on a coupled pre-validated virtual Diesel engine model (GT- Suite ® 1-D air path model) and in-cylinder combustion model (CMCL ® Stochastic Reactor Model Engine Suite). In the context of the considered Engine Simulation Framework, GT Suite + Stochastic Reactor Model (SRM), one fundamental problem is to establish a real time stochastic simulation capability. This problem can be addressed by replacing the slow combustion chemistry solver (SRM) with an appropriate NOx surrogate model. The approach taken in this research for the development of this surrogate model was based on a combination of design of dynamic experiments run on the virtual diesel engine model (GT- Suite), with a dynamic model fitted for the parameters required as input to the SRM, with a zonal design of experiments (DoEs), using Optimal Latin Hypercubes (OLH), run on the SRM model. A response surface model was fitted on the predicted NOx from the SRM OLH DoE data. This surrogate NOx model was then used to replace the computationally expensive SRM simulation, enabling real-time simulations of transient drive cycles to be executed. The performance of the approach was validated on a simulated NEDC drive cycle, against experimental data collected for the engine case study. The capability of methodology to capture the transient trends of the system shows promising results and will be used for the development of global surrogate prediction models for engine-out emissions.

No / Extrusion is one of the major methods for processing polymeric materials and the thermal homogeneity of the process output is a major concern for manufacture of high quality extruded products. Therefore, accurate process thermal monitoring and control are important for product quality control. However, most industrial extruders use single point thermocouples for the temperature monitoring/control although their measurements are highly affected by the barrel metal wall temperature. Currently, no industrially established thermal profile measurement technique is available. Furthermore, it has been shown that the melt temperature changes considerably with the die radial position and hence point/bulk measurements are not sufficient for monitoring and control of the temperature across the melt flow. The majority of process thermal control methods are based on linear models which are not capable of dealing with process nonlinearities. In this work, the die melt temperature profile of a single screw extruder was monitored by a thermocouple mesh technique. The data obtained was used to develop a novel approach of modelling the extruder die melt temperature profile under dynamic conditions (i.e. for predicting the die melt temperature profile in real-time). These newly proposed models were in good agreement with the measured unseen data. They were then used to explore the effects of process settings, material and screw geometry on the die melt temperature profile. The results showed that the process thermal homogeneity was affected in a complex manner by changing the process settings, screw geometry and material. (C) 2013 Elsevier Inc. All rights reserved.

Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: A mineral concentrate drying process consisting of a hot gas generator, a flash dryer and a feeding section is found to be the bottleneck in the platinum concentrate smelting process. This operation is used as a case study for system identification and model-based control of dryers. Based on the availability of a month's worth of dryer data obtained from a historian, a third party modelling and control software vendor is interested in the use of this data for data driven model construction and options for dryer control. The aimed contribution of this research is to use only data driven techniques and attempt an SID experiment and use of this model in a controller found in literature to be applicable to the dryer process. No first principle model was available for simulation or interpretation of results. Data were obtained for the operation from the plant historian, reduced, cleaned and investigated for deterministic information through surrogate data comparison – resulting in usable timeseries from the plant data. The best datasets were used for modelling of the flash dryer and hot gas generator operations individually, with the hot gas generator providing usable results. The dynamic, nonlinear autoregressive models with exogenous inputs were identified by means of a genetic programming with orthogonal least squares toolbox. The timeseries were reconstructed as a latent variable set, or “pseudo-embedding”, using the delay parameters as identified by average mutual information, autocorrelation and false nearest neighbours. The latent variable reconstruction resulted in a large solution space, which need to be investigated for an unknown model structure. Genetic Programming is capable of identifying unknown structures. Freerun prediction stability and sensitivity analysis were used to assess the identified best models for use in model based control. The best two models for the hot gas generator were used in a basic model predictive controller in an attempt to only track set point changes. One step ahead modelling of the flash dryer outlet air temperature was unsuccessful with the best model obtaining a validation R2 = 43%. The lack of process information contained in the available process variables are to blame for the poor model identification. One-step ahead prediction of the hot gas generator resulted in a top model with validation R2 = 77.1%. The best two hot gas generator models were implemented in a model predictive controller constructed in a real time plant data flow simulation. This controller's performance was measured against set point tracking ability. The MPC implementation was unsuccessful due to the poor freerun prediction ability of the models. The controller was found to be unable to optimise the control moves using the model. This is assigned to poor model freerun prediction ability in one of the models and a too complex freerun model structure required. It is expected that the number of degrees of freedom in the freerun model is too much for the optimiser to handle. A successful real time simulation architecture for the plant dataflow could however be constructed in the supplied software. It is recommended that further process measurements, specifically feed moisture content, feed temperature and air humidity, be included for the flash dryer; closed loop system identification be investigated for the hot gas generator; and a simpler model structure with smaller reconstructed latent variable regressor set be used for the model predictive controller. / AFRIKAANSE OPSOMMING: 'n Drogings proses vir mineraal konsentraat bestaan uit drie eenhede: 'n lug verwarmer-, 'n blitsdroeër- en konsentraat toevoer eenheid. Hierdie droeër is geïdentifiseer as die bottelnek in die platinum konsentraat smeltingsproses. Die droeër word gebruik as 'n gevallestudie vir sisteem identifikasie asook model-gebasseerder beheer van droeërs. 'n Maand se data verkry vanaf die proses databasis, het gelei tot 'n derde party industriële sagteware en beheerstelsel maatskappy se belangstelling in data gedrewe modelering en beheer opsies vir die drogings proses. Die doelwit van hierdie studie is om data gedrewe modeleringstegnieke te gebruik en die model in 'n droeër-literatuur relevante beheerder te gebruik. Geen eerste beginsel model is beskikbaar vir simulasie of interpretasie van resultate nie. Die verkrygde data is gereduseer, skoon gemaak en bestudeer om te identifiseer of die tydreeks deterministiese inligting bevat. Dit is gedoen deur die tydreeks met stochastiese surrogaat data te vergelyk. Die mees gepaste datastelle is gebruik vir modellering van die blitsdroeër en lugverwarmer afsonderlik. Die nie-liniêre, dinamiese nie-linieêre outeregressie modelle met eksogene insette was deur 'n genetiese programmering algoritme, met ortogonale minimum kwadrate, identifiseer. Die betrokke tydreeks is omskep in 'n hulp-veranderlike stel deur gebruik te maak van vertragings-parameters wat deur gemiddelde gemeenskaplike inligting, outokorrelasie en vals naaste buurman metodes verkry is. Die GP algoritme is daartoe in staat om the groot oplossings ruimte wat deur hierdie hulp-veranderlike rekonstruksie geskep word, te bestudeer vir 'n onbekende model struktuur. Die vrye vooruitskattings vermoë, asook die model sensitiwiteit is inag geneem tydens die analiese van die resultate. Die beste modelle se gepastheid tot model voorspellende beheer is gemeet deur die uitkomste van 'n sensitiwiteits analise, asook 'n vrylopende voorspelling, in oënskou te neem. Die een-stap vooruit voorspellende model van die droeër was onsusksesvol met die beste model wat slegs 'n validasie R2 = 43% kon behaal. Die gebrekkige meet instrumente in die droeër is te blameer vir die swak resultate. Die een-stap vooruit voorspellende model van die lug verwarmer wat die beste gevaar het, het 'n validasie R2 = 77.1% gehad. 'n Basiese model voorspellende beheerder is gebou deur die 2 beste modelle van slegs die lugverwarmer te gebruik in 'n intydse simulasie van die raffinadery data vloei struktuur. Hierdie beheerder se vermoë om toepaslike beheer uit te oefen, is gemeet deur die slegs die stelpunt te verander. Die beheerder was egter nie daartoe in staat om die insette te optimeer, en so die stelpunt te volg nie. Hierdie onvermoë is as gevolg van die kompleks vrylopende model struktuur wat oor die voorspellingsvenster optimeer moet word, asook die onstabiele vryvooruitspellings vermoë van die modelle. Die vermoede is dat die loslopende voorspelling te veel vryheids grade het om die insette maklik genoeg te optimeer. Die intydse simulasie van die raffinadery se datavloei struktuur was egter suksesvol. Beter meting van noodsaaklike veranderlikes vir die droër, o.a. voginhoud van die voer, voer temperatuur, asook lug humiditeit; geslotelus sisteem identifikasie vir die lugverwarmer; asook meer eenvoudige model struktuur vir gebruik in voorspellende beheer moontlik vermag deur 'n kleiner hulp veranderlike rekonstruksie te gebruik.

Batch distillation with chemical reaction when takes place in the same unit is referred to as batch reactive distillation process. The combination reduces the capital and operating costs considerably. Among many different types of batch reactive distillation column configurations, (a) conventional (b) inverted (c) semi-batch columns are considered here. Three reaction schemes such as (a) esterification of methanol (b) esterification of ethanol (c) hydrolysis of methyl lactate are studied here. Four different types of dynamic optimisation problems such as (a) maximum conversion (b) maximum productivity (c) maximum profit and (d) minimum time are formulated in this work. Optimal design and or operation policies are obtained for all the reaction schemes. A detailed rigorous dynamic model consisting of mass, energy balances, chemical reaction and thermodynamic properties is considered for the process. The model was incorporated within the dynamic optimisation problems. Control Vector Parameterisation (CVP) technique was used to convert the dynamic optimisation problem into a nonlinear programming problem which was solved using efficient SQP (Successive Quadratic Programming) method available within the gPROMS (general PROcess Modelling System) software. It is observed that multi-reflux ratio or linear reflux operation always led to better performance in terms of conversion, productivity for all reaction schemes compared to that obtained using single reflux operation. Feed dilution (in the case of ethanol esterification) led to more profit even though productivity was found to be lower. This was due to reduction in feed price because of feed dilution. Semi-batch reactive distillation opertation (for ethanol esterification) led to better conversion compared to conventional batch distillation, however, the total amount of acetic acid (reactant) was greater in semi-batch operation. Optimisation of design and operation (for ethanol esterification) clearly showed that a single cloumn will not lead to profitable operation for all possible product demand profile. Also change in feed and /or product price may lead to adjust the production target to maximise the profitability. In batch distillation, total reflux operation is recommended or observed at the begining of the operation (as is the case for methnaol or ethanol esterification). However, in the case of hydrolysis, total reflux operation was obseved at the end of the operation. This was due to lactic acid (being the heaviest) was withrawn as the final bottom product.

Le thème central de cette thèse est la conception d’actionneurs doux à partir de matériaux intelligents et d’une prothèse de main robotique souple. Notre approche prends en compte les différents points qui peuvent influer sur le développement d’une stratégie d’actionnement ou d’un muscle artificiel : i) Les mécanismes et la fonctionnalité de la main humaine afin d’identifier les exigences fonctionnelles pour une prothèse de main robotique en matière de préhension. ii) L’analyse et l’amélioration des mécanismes de la main robotique pour intégrer un comportement souple dans la prothèse. iii) L’évaluation expérimentale de la prothèse de main robotique afin d’identifier les spécifications du système d’actionnement nécessaire au fonctionnement cinématique et dynamique du robot. iv) Le développement et la modélisation d’une stratégie d’actionnement utilisant des matériaux intelligents.Ces points sont abordés successivement dans les 4 chapitres de cette thèse1. Analyse du mouvement de la main humaine pour l’identification des exigences technologiques pour la prothèse de main robotique.2. Conception et modélisation de la prothèse de main robotique à comportement souple.3. Evaluation mécatronique de la prothèse de main.4. Conception d’un muscle artificiel basé sur des matériaux intelligents. / In the field of robotic hand prosthesis, the use of smart and soft materials is helpful in improving flexibility, usability, and adaptability of the robots, which simplify daily living activities of prosthesis users. However, regarding the smart materials for artificial muscles, technologies are considered to be far from implementation in anthropomorphic robotic hands. Therefore, the target of this thesis dissertation is to reduce the gap between smart material technologies and robotic hand prosthesis. Five central axes address the problem: i)identification of useful grasping gestures and reformulation of the robotic hand mechanism, ii) analysis of human muscle behavior to mimic human grasping capabilities, iii) modeling robot using the hybrid model DHKK-SRQ for the kinematics and the virtual works principle for dynamics, iv) definition of actuation requirements considering the synergy between prehension conditions and robot mechanism, and v) development of a smart material based actuation system.This topics are addressed in four chapters:1. Human hand movement analysis toward the hand prosthesis requirements2. Design and modeling of the soft robotic hand ProMain-I3. Mechatronic assessment of Prosthetic hand4. Development of an artificial muscle based on smart materials