This study investigates how well the Regional Atmospheric Modelling System (RAMS) simulates the sea breeze from False Bay (False Bay sea breeze) at a small resolution of 200m. It describes the influence of the sea breeze in the Stellenbosch wine growing district focusing on temperature, relative humidity and wind speed and direction through three case studies, using three different synoptic conditions. The RAMS simulations are verified against measurements done by automatic weather stations in the study area for all three case studies. The first synoptic condition investigated is when light onshore flow occurred over the south-western Cape. The RAMS model simulated the vertical and horizontal structure of the sea breeze from False Bay very well. However RAMS predicted the onset of the sea breeze 3 hours earlier than the AWS data predicted. The flow was off-shore in the second case study. The RAMS simulations as well as the observed data from the automatic weather stations, showed the two sea breezes influencing the study area, one from Table Bay, west of Stellenbosch, and one from False Bay. In this case study the model simulated the flatter head and stronger False Bay sea breeze. The third case study investigated the influence of strong onshore synoptic conditions, in which the model and observed values showed that no sea breeze developed from False Bay. From the three case studies it was found that the sea breeze is influenced by the synoptic flow and that the sea breeze causes cooling of between 3°C and 16°C and relative humidity (RH) increase of between 16 – 57% depending on the synoptic flow. RAMS was able to simulate the sea breeze theoretically correct and has the potential to be used to identify climatological areas in the wine growing areas of the Western Cape. / Dissertation (MSc)--University of Pretoria, 2007. / Geography, Geoinformatics and Meteorology / Unrestricted

Motion capture has in recent years grown in interest in many fields from both game industry to sport analysis. The need of reflective markers and expensive multi-camera systems limits the business since they are costly and time-consuming. One solution to this could be a deep neural network trained to extract 3D joint estimations from a 2D video captured with a smartphone. This master thesis project has investigated the accuracy of a trained convolutional neural network, MargiPose, that estimates 25 joint positions in 3D from a 2D video, against a gold standard, multi-camera Vicon-system. The project has also investigated if the data from the deep neural network can be connected to a biomechanical modelling software, AnyBody, for further analysis. The final intention of this project was to analyze how accurate such a combination could be in golf swing analysis. The accuracy of the deep neural network has been evaluated with three parameters: marker position, angular velocity and kinetic energy for different segments of the human body. MargiPose delivers results with high accuracy (Mean Per Joint Position Error (MPJPE) = 1.52 cm) for a simpler movement but for a more advanced motion such as a golf swing, MargiPose achieves less accuracy in marker distance (MPJPE = 3.47 cm). The mean difference in angular velocity shows that MargiPose has difficulties following segments that are occluded or has a greater motion, such as the wrists in a golf swing where they both move fast and are occluded by other body segments. The conclusion of this research is that it is possible to connect data from a trained CNN with a biomechanical modelling software. The accuracy of the network is highly dependent on the intention of the data. For the purpose of golf swing analysis, this could be a great and cost-effective solution which could enable motion analysis for professionals but also for interested beginners. MargiPose shows a high accuracy when evaluating simple movements. However, when using it with the intention of analyzing a golf swing in i biomechanical modelling software, the outcome might be beyond the bounds of reliable results.

Dynamic modelling and optimization of three different processes namely (a) bulk polymerization of styrene, (b) solution polymerization of methyl methacrylate (MMA) and (c) emulsion copolymerization of Styrene and MMA in batch and semi-batch reactors are the focus of this work. In this work, models are presented as sets of differential-algebraic equations describing the process. Different optimization problems such as (a) maximum conversion (Xn), (b) maximum number average molecular weight (Mn) and (c) minimum time to achieve the desired polymer molecular properties (defined as pre-specified values of monomer conversion and number average molecular weight) are formulated. Reactor temperature, jacket temperature, initial initiator concentration, monomer feed rate, initiator feed rate and surfactant feed rate are used as optimization variables in the optimization formulations. The dynamic optimization problems were converted into nonlinear programming problem using the CVP techniques which were solved using efficient SQP (Successive Quadratic Programming) method available within the gPROMS (general PROcess Modelling System) software. The process model used for bulk polystyrene polymerization in batch reactors, using 2, 2 azobisisobutyronitrile catalyst (AIBN) as initiator was improved by including the gel and glass effects. The results obtained from this work when compared with the previous study by other researcher which disregarded the gel and glass effect in their study which show that the batch time operation are significantly reduced while the amount of the initial initiator concentration required increases. Also, the termination rate constant decreases as the concentration of the mixture increases, resulting rapid monomer conversion. The process model used for solution polymerization of methyl methacrylate (MMA) in batch reactors, using AIBN as the initiator and Toluene as the solvent was improved by including the free volume theory to calculate the initiator efficiency, f. The effects of different f was examined and compared with previous work which used a constant value of f 0.53. The results of these studies show that initiator efficiency, f is not constant but decreases with the increase of monomer conversion along the process. The determination of optimal control trajectories for emulsion copolymerization of Styrene and MMA with the objective of maximizing the number average molecular weight (Mn) and overall conversion (Xn) were carried out in batch and semi-batch reactors. The initiator used in this work is Persulfate K2S2O8 and the surfactant is Sodium Dodecyl Sulfate (SDS). Reduction of the pre-batch time increases the Mn but decreases the conversion (Xn). The sooner the addition of monomer into the reactor, the earlier the growth of the polymer chain leading to higher Mn. Besides that, Mn also can be increased by decreasing the initial initiator concentration (Ci0). Less oligomeric radicals will be produced with low Ci0, leading to reduced polymerization loci thus lowering the overall conversion. On the other hand, increases of reaction temperature (Tr) will decrease the Mn since transfer coefficient is increased at higher Tr leading to increase of the monomeric radicals resulting in an increase in termination reaction.

Today, ocean modeling is fast developing as a versatile tool for the study of earth’s climate, local marine ecosystems and coastal engineering applications. Though the field of ocean modeling began in the early 1950s along with the development of climate models and primitive computers, even today, the state-of-the-art ocean models have their own limitations. Many issues still remain such as the uncertainity in the parameterisation of essential processes that occur on spatial and temporal scales smaller than that can be resolved in model calculations, atmospheric forcing of the ocean and the boundary and initial conditions. The advent of data assimilation into ocean modeling has heralded a new era in the field of ocean modeling and oceanic sciences. “Data assimilation” is a methodology in which observations are used to improve the forecasting skill of operational meteorological models. The study in the present thesis mainly focuses on obtaining a four dimensional realization (the spatial description coupled with the time evolution) of the oceanic flow that is simultaneously consistent with the observational evidence and with the dynamical equations of motion and to provide initial conditions for predictions of oceanic circulation and tracer distribution. A good implementation of data assimilation can be achieved with the availability of large number of good quality observations of the oceanic fields as both synoptic and in-situ data. With the technology in satellite oceanography and insitu measurements advancing by leaps over the past two decades, good synoptic and insitu observations of oceanic fields have been achieved. The current and expected explosion in remotely sensed and insitu measured oceanographic data is ushering a new age of ocean modeling and data assimilation. The thesis presents results of analysis of the impact of data assimilation in an ocean general circulation model of the North Indian Ocean. In this thesis we have studied the impact of assimilation of temperature and salinity profiles from Argo floats and Sea Surface height anomalies from satellite altimeters in a Sigma-coordinate Indian Ocean model. An ocean data assimilation system based on the Regional Ocean Modeling System (ROMS) for the Indian Ocean is used. This model is implemented, validated and applied in a climatological simulation experiment to study the circulation in the Indian Ocean. The validated model is then used for the implementation of the data assimilation system for the Indian Ocean region. This dissertation presents the qualitative and quantitative comparisons of the model simulations with and without subsurface temperature and salinity profiles and sea surface height anamoly data assimilation for the Indian Ocean region. This is the first ever reported data assimilation studies of the Argo subsurface temperature and salinity profile data with ROMS in the Indian Ocean region.

Η διενέργεια εμβιομηχανικών μελετών σε μοντέλο με τη βοήθεια ηλεκτρονικών υπολογιστών βρίσκεται σήμερα σε προχωρημένο στάδιο εξέλιξης. Σε αυτή την εξέλιξη κεντρική θέση κατέχουν λογισμικά δύο κατηγοριών. Στην πρώτη κατηγορία κατατάσσονται τα λογισμικά εμβιομηχανικής προσομοίωσης του ανθρωπίνου σώματος και στη δεύτερη κατηγορία τα λογισμικά ανάλυσης πεπερασμένων στοιχείων. Σε αυτή τη Μεταπτυχιακή Εργασία έγινε μία προσπάθεια διερεύνηση της συνεργασίας των δύο αυτών κατηγοριών λογισμικού με την κινηματική μελέτη ενός οσφυϊκού σπονδύλου και την ανάλυση φορτίσεών του με την μέθοδο των πεπερασμένων στοιχείων. Για αυτό το λόγο επιλέχτηκαν δύο λογισμικά εμπορικά διαθέσιμα. Το λογισμικό εμβιομηχανικής προσομοίωσης Anybody modeling system και το λογισμικό ανάλυσης πεπερασμένων στοιχείων Ansys multiphysics. Στο Πρώτο κεφάλαιο γίνεται παρουσίαση του λογισμικού Anybody. Πιο συγκεκριμένα. αναφέρονται τα στοιχεία εκείνα που υλοποιούν ένα μοντέλο του ανθρώπινου σώματος (τμήματα, αρθρώσεις, μύες, σύνδεσμοι) καθώς και οι μελέτες που μπορούν να εκτελεστούν δηλαδή η κινηματική και η δυναμική. Κύρια θέση κατέχει η αντιστροφή δυναμική μελέτη που χαρακτηρίζεται από την εξαγωγή συμπερασμάτων για τις δυνάμεις και τις ροπές που αναπτύσσονται σε ένα σώμα αφού έχει περιγραφεί εκ των προτέρων η κίνησή του. Στο Δεύτερο κεφάλαιο γίνεται μια λεπτομερής περιγραφή της ανατομίας της σπονδυλικής στήλης στην οποία αναφέρονται τα επιμέρους κοινά στοιχεία που έχουν οι σπόνδυλοι καθώς κου οι διαφορές στις διαφορετικές μοίρες της σπονδυλικής στήλης. Μετά την ανατομική περιγραφή παρατίθεται η εμβιομηχανική θεώρηση της κατασκευής της οσφυϊκής μοίρας της σπονδυλικής στήλης, αναλύοντας τα επιμέρους δομικά στοιχεία από μηχανική άποψη και η λειτουργικότητά τους. Στο Τρίτο κεφάλαιο περιγράφεται η κατασκευή ενός μοντέλου της σπονδυλικής στήλης στο λογισμικό Anybody το οποίο υποβάλλεται σε κινήσεις κάμψης, έκτασης, πλάγιας κάμψης και στροφής και επιχειρείται ο σχολιασμός των ευρημάτων. Τέλος, στο τέταρτο κεφάλαιο τα δεδομένα τα οποία παράγει η αντίστροφή μελέτη και συγκεκριμένα οι φορτίσεις που δέχεται ο Ο5 σπόνδυλος κατά τις κινήσεις στις οποίες υποβάλλεται η οσφυϊκή μοίρα χρησιμοποιούνται ως δεδομένα εισόδου για την ανάλυση του Ο5 σπόνδυλο με το λογισμικό μηχανικής ανάλυσης πεπερασμένων στοιχείων ANSYS. Συνοψίζοντας, η συνεργασία των δύο λογισμικών αποδείχθηκε εφικτή και πρόσφορη. Στην παρούσα μεταπτυχιακή εργασία αναπτύχθηκε η βασική τεχνογνωσία ως προς την χρήση του λογισμικού Anybody Modeling System και την συστηματοποίηση της διασύνδεσης του με το λογισμικό Ansys με αποτέλεσμά να αποτελεί την βάση για περαιτέρω εργασίες. / The conduction of biomechanical studies on models with the aid of computers is currently at an advanced stage. In this essay, the central position is hold by two software categories. In the first category are classified various software of biomechanical simulation of the human body and in the second category are classified the software for the finite element analysis. In this Master Thesis was made an attempt to explore the cooperation of these two kinds of software. For this reason, two commercially available softwares were selected. The biomechanical simulation was performed using the Anybody Modeling System software and the finite element analysis was performed using the Ansys Multiphysics software. In the first chapter the use of the Anybody software was presented. More specifically, those elements that implement a model of the human body (segments, joints, muscles, ligaments) as well as studies that can be performed i.e. the kinematics and dynamics studies were discussed in details. The inverse dynamics study has been characterized as the main feature of the software allowing to explore the resulting forces and torques developed in a body during the in advance described movement. The second chapter includes a detailed description of the anatomy of the spine. After the anatomical description the biomechanical approach is presented, analyzing each individual component from engineering point of view as well as their functionality. The third chapter describes the construction of a model of the spine in the Anybody software that is subjected to flexion, extension, lateral bending and rotation along with the results. Finally, in the fourth chapter the data that produces the inverse study namely the loads applied to the L5 vertebra during each movement performed by the lumbar spine are used as input data for the mechanical analysis of L5 vertebra with the finite element analysis software ANSYS. As a conclusion, the collaboration of these two software programmes proved to be feasible and appropriate. In this master thesis the basic knowledge in the use of software Anybody Modeling System has been developed and an interface with the software Ansys has been built thus forming the basis for further work.

No description available.

After the seminal works by Freeze and Harlan (1969), the scientific community realized that groundwater and vadose zone equation were breaking up. Hydrologists split into three communities following the motto “you are my boundary condition”: groundwater people, vadose zone scientists and surface water hydrologists. This compartmentalization of the scientific community fostered a deepening of knowledge in single branches, allowing to break things down into simple parts. However, this division represented an obstacle to the comprehension of the complexity that characterises the interactions between them. Eventually, this separation of the communities continued into software code. As a matter of fact, the boundary conditions were hard-wired, but they offered a poor representation of the physics in the interaction between different domains. Recently, there has been a renewed interest in studying the big picture, the interactions between different domains. This it is evident in the development of a new research field named the Earth’s Critical Zone (CZ). It is defined as the “ heterogeneous, near surface environment in which complex interactions involving rock, soil, water, air, and living organism regulate the natural habitat and determine the availability of life-sustaining resources” (National Research Council, 2001). Further interest in the studying the CZ is given by the ever-increasing pressure due to the growth in human population, wealth, and climatic changes. This thesis focuses on the CZ while recognising the central role of having a solid set of tools for modeling the water movements in all conditions. Recently, Prentice et al. (2015) identified Reliable, Robust, and Realistic, the three R’s, as the three characteristics that numerical models should have. Soil moisture is one of the key components to simulate the processes in the critical zone. The governing equation to describe the water flow in a porous material is know as the Richards equation and it dates back to 1931.The numerical solution of the Richards equation is far from trivial because of its mildly nonlinearity and it is often discarded in favour of more empirical models. After the pioneering work by Celia et al. (1990), a lot of work has been done in this direction and several model, for instance Hydrus, GEOtop, Cathy, Parflow adopted variants of the Newton algorithm to allows global convergence. Since Casulli and Zanolli (2010), anticipated by Brugnano and Casulli (2008), a new method called nested Newton has been found to guarantee convergence in any situation, even under the use of large time steps and grid sizes. The research presented in this thesis used this integration algorithm. Besides the numerical aspect, another issue was the correct definition of the boundary condition at the soil surface. As a matter of fact, the definition of the surface boundary condition is necessary to capture the generation of surface run-off. In the literature several approaches were proposed to couple surface and subsurface flow, and in this work the approach presented by Gugole (2016) has been used. The novelty regarded the discretization of the shallow water equation and the Richards equation in an unique algebraic system that was solved in a conservative manner. Richards equation was criticized from many points of view, but it is difficult to criticize its core mass conservation. The definition of the hydraulic properties of the soil, including both the soil water retention function (SWRC) and the hydraulic conductivity models, often uses simplified representation of the pore system describing it as bundle of cylindrical capillaries where the largest ones drain first and are filled last. As pointed out by Bachmann et al. (2002), “physical effects, like surface water film adsorption, capillary condensation and surface flow in liquid films, as well as volumetric changes of the pore space are often ignored”. Thus, the capillary bundle concept is a rough, even if still useful approximation of soil reality. From these observations, during the research the code has been designed to offer the opportunity to easily implement new soil water hydraulic models that might be proposed in the future. The Richards’ equation alone is not anymore sufficient to model the water flow in soils. In fact, soil temperature affects the water flow in soils. This is evident in cold regions where soil water is subject to freezing and thawing processes, but also in unfrozen soil, where temperature modifies water properties such as viscosity, the surface tension, and the contact angle. These microscopic variations of the water physical properties have significant impacts in the mass and energy budget within the CZ. For instance, it has been observed that the infiltration rates between the stream and the vadose zone show a clear diurnal pattern: infiltration rates are highest in late afternoon, when stream temperature is greatest, and they are lowest in early morning when stream temperature is least. In cold regions the run-off production is strongly affected by the presence of ice with the soil. Nonetheless, soil moisture modifies the thermal properties of the soil: water is characterised by a high thermal inertia and the thermal conductivity of ice is almost four times larger than that of liquid water, and water flow carries a significant amount of sensible heat. These aspects come under one the R of realistic. Hence, the Richards’ equation has been coupled with the energy equation for the unfrozen case. Moreover, the research developed a model to study the heat transfer considering the phase change of water. In both cases robust numerical schemes have been used. There are few models that already coupled the equations. One of these models is GEOtop that was conceived and built in the research group where this work was carried out. Such models have some limitations. One of the main limitations regards their implementations. In fact, these models were built as a monolithic code and this turns in difficulties in maintaining and developing existing codes. In this work the codes have been developed by using Design Patterns. As a result, the codes are easy to maintain, to extend, and to reuse. Considering the CZ, these aspects are of crucial importance. Researchers should have a model that can be extended to include more processes, i.e. increase its complexity and avoiding the code to become too complicated. The models were integrated in the Object Modelling System v3 (OMS3) framework. The system provides various components for precipitation treatment, radiation estimation in complex terrain, evaporation and transpiration that can be connected to each other’s for generating inputs and outputs. Due to the modularity of the system, whilst the components were developed and can be enhanced independently, they can be seamlessly used at run time by connecting them with the OMS3 DSL language based on Groovy. OMS3 provides the basic services and, among them, tools for calibration and implicit parallelization of component runs. In sum, the thesis analyses the relevant literature to date. It presents a detailed description of the physical processes related to the water flow and the energy budget within the soil. Then, it describes the numerical method used to solve and coupled the equations. It also provides the informatics behind WHETGEO 1D (Water HEat Tracers in GEOframe). Finally, the work focuses on the WHETGEO extension for the bidimensional case by showing how the code can be designed to store grid information.

Dynamic modelling and optimization of three different processes namely (a) bulk polymerization of styrene, (b) solution polymerization of methyl methacrylate (MMA) and (c) emulsion copolymerization of Styrene and MMA in batch and semi-batch reactors are the focus of this work. In this work, models are presented as sets of differential-algebraic equations describing the process. Different optimization problems such as (a) maximum conversion (Xn), (b) maximum number average molecular weight (Mn) and (c) minimum time to achieve the desired polymer molecular properties (defined as pre-specified values of monomer conversion and number average molecular weight) are formulated. Reactor temperature, jacket temperature, initial initiator concentration, monomer feed rate, initiator feed rate and surfactant feed rate are used as optimization variables in the optimization formulations. The dynamic optimization problems were converted into nonlinear programming problem using the CVP techniques which were solved using efficient SQP (Successive Quadratic Programming) method available within the gPROMS (general PROcess Modelling System) software. The process model used for bulk polystyrene polymerization in batch reactors, using 2, 2 azobisisobutyronitrile catalyst (AIBN) as initiator was improved by including the gel and glass effects. The results obtained from this work when compared with the previous study by other researcher which disregarded the gel and glass effect in their study which show that the batch time operation are significantly reduced while the amount of the initial initiator concentration required increases. Also, the termination rate constant decreases as the concentration of the mixture increases, resulting rapid monomer conversion. The process model used for solution polymerization of methyl methacrylate (MMA) in batch reactors, using AIBN as the initiator and Toluene as the solvent was improved by including the free volume theory to calculate the initiator efficiency, f. The effects of different f was examined and compared with previous work which used a constant value of f 0.53. The results of these studies show that initiator efficiency, f is not constant but decreases with the increase of monomer conversion along the process. The determination of optimal control trajectories for emulsion copolymerization of Styrene and MMA with the objective of maximizing the number average molecular weight (Mn) and overall conversion (Xn) were carried out in batch and semi-batch reactors. The initiator used in this work is Persulfate K2S2O8 and the surfactant is Sodium Dodecyl Sulfate (SDS). Reduction of the pre-batch time increases the Mn but decreases the conversion (Xn). The sooner the addition of monomer into the reactor, the earlier the growth of the polymer chain leading to higher Mn. Besides that, Mn also can be increased by decreasing the initial initiator concentration (Ci0). Less oligomeric radicals will be produced with low Ci0, leading to reduced polymerization loci thus lowering the overall conversion. On the other hand, increases of reaction temperature (Tr) will decrease the Mn since transfer coefficient is increased at higher Tr leading to increase of the monomeric radicals resulting in an increase in termination reaction.

Cette thèse étudie l’impact de l’Aéroport international de Beyrouth sur la qualité de l’air de Beyrouth et ses banlieues par mesures et modélisation des COVs et NO2. Il s’agit de la première étude qui identifie les signatures des émissions (COVs) issues des avions sous opération réelle. Grâce aux signatures détectées lors de 4 campagnes réalisées, nous constatons que l’aéroport a un impact sur la qualité de l’air de son voisinage, la zone côtière (trajectoire d’atterrissage), et les zones montagneuses. Ces résultats sont confirmés via le modèle ADMS-Airport, utilisé pour la première fois au Moyen-Orient et validé pour les conditions libanaises (r = 0.86). Par ailleurs, les concentrations de 47 COVs ont été mesurées pour la première fois à l'intérieur d’un bâtiment de l'aéroport. Les teneurs en COVs qui sont corrélées au nombre d’avions sont en dessous des valeurs seuils sauf pour l'acroléine alors que la celle de NO2 peut constituer un danger pour la santé. / This work mainly investigated the impact of Beirut Airport on the air quality of Beirut and its suburbs via both measurements and modeling of VOCs and NO2. This is the first study to determine VOC signatures of exhaust emissions from aircraft under real operation. Using these signatures, the impact of the airport activities was tracked in 4 transect campaigns, where it was found that the airport impacts air quality not only in its vicinity, but also on the seashore (landing jet trajectory) and in mountainous areas. These results were confirmed via modeling with ADMS-Airport, implemented for the first time in the Middle East, after being validated in the Lebanese conditions (r = 0.86). As a secondary goal, and for the first time, 47 VOCs were assessed inside an airport building. Measured VOC levels did not present any risks except for acrolein. In the arrivals hall, NO2 levels indicated a health hazard; while a direct relationship was found between aircraft number and VOC concentrations.