Dissertations / Theses on the topic 'Cake structure'

<p>Some products share one or two modules and while developing these products, structural optimization with stiffness as the objective function can be a useful tool. There might be no or very little CAD-data available in the pre-development phase and it is not certain that existing designs can be, or is desirable to use as a reference. The main objective of this thesis is to establish an accurate and fast-to-use methodology which can be utilized while developing new cars.</p><p>In this thesis, the Volvo products S40, V50 and C70 serve as a basis for this case study. All the models are beam structures and the masses of components are added as point and line masses. Several optimization analyses are performed on one or three products exposed to seven load cases. Additional analyses with shell elements, more simplified models and changed load case balance achieved by normalization of the different load case compliances are also studied to investigate how these factors influence the results.</p><p>Analyses show that front crash to a great extent dominates the results while normalization increases the influence of the remaining load cases. Since front crash is dominating and the front area is shared in all products, the performance is remarkably similar when three products are optimized compared to separate analyses of one product. Analysis of models without added point or line masses gives a result which greatly differs from previous results and therefore shows that added masses are required. The methodology is applicable to develop products and detect new load paths through the car.</p>

Coastal anthropogenic infrastructure has significantly modified nearshore environments. Because these structures often have a strong association with shipping as would be found in ports and harbors, they have been identified as invasion hotspots. Due to propagule pressure from shipping and recreational boating and suitable uncolonized substrate that provides a refuge from native predators, a greater number of non-native species have been found on these structures compared to nearby natural substrate. The mechanisms that limit the spread of non-native species from anthropogenic structures to natural substrate have been explored for several taxa at a species-specific level, but less so from an overall community perspective. Predation has been identified as one of the biotic interactions limiting invasion success. In addition to predation, dispersal ability may also prevent the spread of non-native species from anthropogenic structures to natural substrate. This thesis addresses how these two mechanisms interact to limit the spread of non-native species from anthropogenic structures to natural substrate and how that alters overall community composition. I aimed to explore differences between communities inside and outside of a marina and determine the extent to which predator and dispersal limitation were structuring these communities. I used a three-factor design, deploying seven unglazed ceramic tiles per each treatment combination of 1) inside versus outside a marina in Yaquina Bay, Oregon; 2) cage keeping out predators greater than the mesh size, no cage, or partial cage; 3) fixed near the substrata (benthic) versus suspended 1 meter below the surface. I also transplanted caged, suspended tiles of either adults or recruits from inside the marina to benthic and suspended caging treatments outside of the marina. These tiles allowed me to examine predation when dispersal limitation was not a factor for the community inside the marina, i.e. what happens to both recruits and adults if they can get outside of the marina. I found that the communities inside and outside of the marina were different and the data suggest that both predation and dispersal limitation interact to limit the spread of non-native species. Additionally, I found that mesopredators that could fit through the caging may be influencing predation results and community structure. This research addresses gaps in scientific knowledge regarding the mechanisms that prevent or facilitate the spread of non-native species. Future work could include the further exploration of mesopredation as an important factor in limiting the spread of non-native species and exploring dispersal limitation more in depth as well as broadening the geographic scope to see if the same trends hold true across bays and bioregions.

Scărişoara Ice Cave has been a catalyst of scientific intrigue and effort for over 150 years. These efforts have revealed and described countless natural phenomena – and in the process have made it one of the most studied caves in the world. Of especial interest is the massive ice block located within its Great Hall and scientific reservations. The ice block, which is the oldest and largest known to exist in a cave, has been the focus of multiple surveying and mapping efforts, typically ones utilizing traditional equipment. In this study, the goals were to reconstruct the ice block/cave floor interface and to estimate the volume of the ice block. Once the models were constructed, we aimed to study the relationships between the cave and ice block morphologies. In order to accomplish this goal, three (3) main datasets were collected, processed, and amalgamated. Ground penetrating radar data was used to discern the floor morphology below the ice block. Over 1,500 photographs were collected in the cave and used with Structure from Motion photogrammetry software to construct a texturized 3D model of the cave and ice surfaces. And a total station survey was performed to scale, georeference, and validate each model. Once georeferenced, the data was imported into an ArcGIS geodatabase for further analysis. The methodology described within this study provides a powerful set of instructions for producing highly valuable scientific data, especially related to caves. Here, we describe in detail the novel tools and software used to validate, inspect, manipulate, and measure morphological information while immersed in a fully 3D experience. With this methodology, it is possible to easily and inexpensively create digital elevation models of underground rooms and galleries, to measure the differences between surfaces, to create 3D models from the combination of surfaces, and to intimately inspect a subject area without actually being there. At the culmination of these efforts, the partial ice block volume was estimated to be 118,000 m3 with an uncertainty of ± 9.5%. The volume computed herein is significantly larger than previously thought and the total volume is likely significantly larger, since certain portions were not modeled during this study. In addition, the morphology of ceiling enlargement was linked to areas of high elevation at the base of the ice block. A counterintuitive depression was recognized at the base of the Entrance Shaft. The thickest areas of the ice were identified for future coring projects. And combining all this a new informational allowed us to propose a new theory on the formation of the ice block and to decipher particular speleogenetic aspects.

As the need for community care increases, complete and up-to-date information about organizational structure is crucial to making appropriate decisions about the expansion of adult day services. The absence of uniform national policies results in states and communities being relegated to balancing limited funds with the demand for adult day services, and in many areas, the lack of adult day care centers altogether. This study provides an overview of the types of state reimbursement, the availability of different funding sources, and the utilization of the sources in various states.

To effectively and substantively impact the realization of school improvement goals, there is a perceived need for the implementation of participatory processes that involve parents, patrons, students, and educators through decentralization of the planning, programming, and implementation phases. Related to this need is the pressing requirement of providing educational leaders with a greater understanding of what knowledge and skills they should possess to effectively guide and direct the implementation of decentralized participatory processes. An exploratory case study of a nationally recognized middle school's decentralized participatory structure was conducted. The purpose of this study was to provide the comprehensive context of an existing decentralized participatory structure from which needed knowledge and skills could be determined. The likelihood of successfully installing future partnership structures can be increased by providing educational leaders with a description, analysis, and interpretation of participatory involvements. The conclusions for the case study were arrived at through a triangulation approach of key-informant interviewing, participant observation at meetings, and an investigation of essential documents. This researcher concluded that the following skills and knowledge base are important for participatory leaders to possess to successfully implement, direct, and guide a decentralized partnership program: Skills. (1) Group dynamic skills; (2) Human relationship skills; (3) Communication skills; (4) Decision-making skills. Knowledge Base. A participatory leader must possess knowledge of (1) how to positively channel diversity, (2) motivation theory and ways to capitalize on motivation theory, (3) ways to develop participants' capacity to participate effectively, (4) how to effectively facilitate the communication and coordination between and among identifiable groups which interlace with the participatory process, (5) the school effectiveness literature, (6) how to balance high task and high relationship, (7) how people learn most effectively, (8) goal theory and ways to set goals through other people, (9) effective planning procedures, (10) change strategy and how to effectively accomplish goals through other people, (11) the benefits of participatory decision-making, (12) the benefits of decentralization, (13) a range of leadership styles, (14) effective management practices, and (15) how to model a decentralized participatory structure.

To meet the need of lightweight chassis in the near future, a technological step of introducing anisotropic materials like Carbon Fibre Reinforced Plastics (CFRP) in structural parts of cars is a possible way ahead. Though there are commercially available tools to find suitability of Fibre Reinforced Plastics (FRPs) and their orientations, they depend on numerical optimization and complexity increases with the size of the model. Nevertheless, the user has a very limited control of intermediate steps. To understand the type of material system that can be used in different regions for a lightweight chassis, especially during the initial concept phase, a more simplified, yet reliable tool is desirable.The thesis aims to provide a framework for determining fibre orientations according to the most-ideal loading path to achieve maximum advantage from FRP-materials. This has been achieved by developing algorithms to find best-fit material orientations analytically, which uses principal stresses and their orientations in a finite element originating from multiple load cases. This thesis takes inspiration from the Durst criteria (2008) which upon implementation provides information on how individual elements must be modelled in a component subjected to multiple load cases. This analysis pre-evaluates the potential of FRP-suitable parts. Few modifications have been made to the existing formulations by the authors which have been explained in relevant sections.The study has been extended to develop additional MATLAB subroutines which finds the type of laminate design (uni-directional, bi-axial or quasi-isotropic) that is suitable for individual elements.Several test cases have been run to check the validity of the developed algorithm. Finally, the algorithm has been implemented on a Body-In-White subjected to two load cases. The thesis gives an idea of how to divide the structure into sub-components along with the local fibre directions based on the fibre orientations and an appropriate laminate design based on classical laminate theory.

In this study of energy pathways in karst groundwater the first chapter examines spatial and temporal patterns of bacterial density and activity in the Dorvan-Cleyzieu karst aquifer, France. During baseflow, bacterial density and activity in the water column was similar in upper and lower zones of the aquifer. Floods apparently scoured inactive bacteria from the aquifer matrix but had little effect on respiring cells. Dissolved organic carbon was more abundant at the base of the aquifer, probably because of patchy distribution of particulate organic matter in upper aquifer zones that leached dissolved organic carbon. The temporal sequence of flooding and drying in the aquifer appears to play an important role in the maintenance of biofilms which should be important energy sources to higher trophic levels in the aquifer. The ecosystem expansion and contraction model, originally developed to describe surface streams, may be a good descriptor of spatial and temporal patterns of microbial films in karst aquifers. The process of leaf and wood breakdown in cave streams in Organ Cave, West Virginia is examined in Chapter 2. Leaf and wood breakdown rates and microbial biomass and respiration on leaves and wood were compared between cave streams with and without coarse particulate organic matter (CPOM) input from the surface to examine the role of CPOM input in leaf and wood breakdown. Breakdown rate and pattern of microbial colonization of leaves and wood were typical of results reported for surface streams. Unlike in surface streams, CPOM input did not influence breakdown rate or microbial colonization on leaves and wood, apparently because nutrients are not limiting in cave streams. Nutrient addition had little effect on microbial films on wood in either stream type. Gammarus minus is an important shredder in Organ Cave streams and G. minus colonization accelerated leaf breakdown rates. Leaf and wood transport rates were low and, when combined with breakdown rates, suggest that CPOM will be retained and transformed to fine particles near its entry point to the subsurface. In chapter 3 I examine cave stream food web structure and the role various organic matter sources in stream trophic dynamics. I used stable isotope (13C and 15N) natural abundance analysis and a 13C-acetate tracer release to establish feeding relationships and to trace the use and importance of bacterial carbon in cave streams with and without CPOM input. Cave streams contained three trophic levels consisting of organic matter sources, primary consumers, and predators. Patterns of 13C labeling in the stream were similar to that in similar studies of surface streams. 13C acetate was incorporated into epilithic biofilms and fine benthic organic matter (FBOM). Some primary consumers, Fontigens tartarea, Gyraulus parvus, and Physa were highly labeled and showed a longitudinal labeling pattern consistent with the consumption of epilithic biofilms. An epigean caddisfly, Dolophilodes, was highly labeled and probably feeds on suspended organic matter. Other primary consumers, Gammarus minus and Caecidotea holsingeri, feed on FBOM and epilithon. Two amphipods, Stygobromus emarginatus and S. spinatus, and a planarian, Macrocotyla hoffmasteri, are predators in the streams. Leaves and wood were not major energy sources directly used by stream animals. Dissolved organic matter (DOM) originating from soils appears to be the primary energy source for stream food webs by fueling bacterial production that is then used by higher trophic levels. Because epilithon C turnover times were relatively long (12.7 - 17 days), DOM can be immobilized in cave stream biofilms, enhancing the efficiency with which the microbial loop may transfer energy to higher trophic levels.<br>Ph. D.

Orientador: João Alberto Venegas Requena<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo<br>Made available in DSpace on 2018-08-09T16:24:16Z (GMT). No. of bitstreams: 1 Souza_MauricioGuilhermeQuilez_M.pdf: 5444391 bytes, checksum: f64376df9364d46cfcb18e6ba06eff3a (MD5) Previous issue date: 2006<br>Resumo: Este trabalho tem como objetivo o desenvolvimento de códigos de computador que têm a finalidade de automatizar as etapas principais de um projeto de estruturas metálicas através das linguagens AutoLISP e Delphi5. Os projetos de estruturas metálicas em estudo são os de coberturas com treliças planas constituídas de barras com perfis tubulares laminados sem costuras e seus contraventamentos. Estes perfis tubulares, ainda pouco utilizados em estruturas planas no Brasil, vêm sendo disseminados através do uso de programas que ajudam os engenheiros a utilizá-los adequadamente em seus projetos tendo em vista que resultam em estruturas mais leves e de fácil fabricação. Desta forma, houve a necessidade de desenvolver um sistema CAD/CAE, para automatizar a geração das geometrias das estruturas planas, além das representações gráficas do sistema geral tridimensional de contraventamentos da estrutura - CAD; exportar os dados para um programa integrado que realiza um processo otimizado de toda a análise estrutural e dimensionamento - CAE e, finalmente, retornar os dados processados para o ambiente CAD, para realizar o detalhamento automático das ligações da estrutura treliçada analisada. Todos os procedimentos adotados para automação dos projetos seguem recomendações de normas técnicas brasileiras principalmente a NBR8800/1986<br>Abstract: This work has as objective to show a software that have the goal to automate the main stages of a steel structural design, using AutoLISP and Delphi5 languages. The steel structural designs in case are the roofs formed by plane trusses made by hollow sections frames. These hollow steel sections, which are not highly used in plane structures in Brazil, are being disseminated by the use of softwares that help civil engineers to use them correctly in their designs, in view of that they result in less weighted and easy manufactured structures. So, there is the necessity to develop a CAD/CAE system, that will automate the generation of the geometries from plane structures and the graphical designs from the three-dimentional general system - CAD; also, we have the necessity to export the data to an integrated computer program that executes an optimized process from the entire structural analysis and design - CAE; and, finaly, to return the proceeded data back to CAD environment, to draw the automatic details from the connections of the analyzed structure. All the procedures and methods used to automate the design follows the specifications of Brazilian Design Codes, mainly the NBR-8800/1986<br>Mestrado<br>Estruturas<br>Mestre em Engenharia Civil

L’idée centrale de notre analyse sur l’économie française concerne la suprématie des taux d’intérêt et des dépenses publiques comme instruments de politique économique. Avec la forte hausse des taux d’intérêt au début des années 1980, les entreprises non financières ont commencé à demander moins de crédit, tandis que les ménages français, ainsi que d’autres économies en voie de développement en ont demandé davantage. Parallèlement à ces développements, les marchés spéculatifs ont dominé la bourse, le taux de chômage a augmenté, et un processus de libéralisation a suivi. Nous analysons les conséquences de ce processus de financiarisation et certains scénarios possibles en France, tout en utilisant un modèle de type Cowles Commission, qui est à son tour fondé sur la littérature stock-flux. Une attention particulière est donnée aux variables de répartition et fiscales. Les résultats du modèle indiquent que (étant donné que les entreprises françaises sont prises dans une trappe à liquidité) le taux d’intérêt a perdu son pouvoir comme une variable de politique. En revanche, les dépenses publiques ont une puissance expansionniste importante<br>The core of our analysis of the French economy concerns the supremacy of interest rates and government spending as policy instruments in this economy. With the strong increase in interest rates at the beginning of the 1980s, non-financial firms started to demand less credit, whereas French households and other developing economies demanded more. Parallel to these developments, bulls became more abundant in stock markets, the unemployment rate soared and a full process of liberalization ensued. We analyze the consequences of this financialization process and some feasible scenarios in France by means of a Cowles Commission-type model that is in turn based on the stock-flow literature. Particular emphasis is given to distributive and fiscalvariables. The model’s results indicate that (given that French firms are caught in a liquidity trap) the interest rate has lost its power as a policy variable. In contrast, public spending has an important expansionary power

La classification est l’un des défis important en bioinformatique, aussi bien pour les données protéiques que nucléiques. La présence de ces données en grandes masses, leur ambiguïté et en particulier les coûts élevés de l’analyse in vitro en termes de temps et d’argent, rend l’utilisation de la fouille de données plutôt une nécessité qu’un choix rationnel. Cependant, les techniques fouille de données, qui traitent souvent des données sous le format relationnel, sont confrontés avec le format inapproprié des données biologiques. Par conséquent, une étape inévitable de prétraitement doit être établie. Cette thèse traite du prétraitement de données protéiques comme une étape de préparation avant leur classification. Nous présentons l’extraction de motifs comme un moyen fiable pour répondre à cette tâche. Les motifs extraits sont utilisés comme descripteurs, en vue de coder les protéines en vecteurs d’attributs. Cela permet l’utilisation des classifieurs connus. Cependant, la conception d’un espace appropié d’attributs, n’est pas une tâche triviale. Nous traitons deux types de données protéiques à savoir les séquences et les structures 3D. Dans le premier axe, i:e:; celui des séquences, nous proposons un nouveau procédé de codage qui utilise les matrices de substitution d’acides aminés pour définir la similarité entre les motifs lors de l’étape d’extraction. En utilisant certains classifieurs, nous montrons l’efficacité de notre approche en la comparant avec plusieurs autres méthodes de codage. Nous proposons également de nouvelles métriques pour étudier la robustesse de certaines de ces méthodes lors de la perturbation des données d’entrée. Ces métriques permettent de mesurer la capacité d’une méthode de révéler tout changement survenant dans les données d’entrée et également sa capacité à cibler les motifs intéressants. Le second axe est consacré aux structures protéiques 3D, qui ont été récemment considérées comme graphes d’acides aminés selon différentes représentations. Nous faisons un bref survol sur les représentations les plus utilisées et nous proposons une méthode naïve pour aider à la construction de graphes d’acides aminés. Nous montrons que certaines méthodes répandues présentent des faiblesses remarquables et ne reflètent pas vraiment la conformation réelle des protéines. Par ailleurs, nous nous intéressons à la découverte, des sous-structures récurrentes qui pourraient donner des indications fonctionnelles et structurelles. Nous proposons un nouvel algorithme pour trouver des motifs spatiaux dans les protéines. Ces motifs obéissent à un format défini sur la base d’une argumentation biologique. Nous comparons avec des motifs séquentiels et spatiaux de certains travaux reliés. Pour toutes nos contributions, les résultats expérimentaux confirment l’efficacité de nos méthodes pour représenter les séquences et les structures protéiques, dans des tâches de classification. Les programmes développés sont disponibles sur ma page web http://fc.isima.fr/~saidi<br>The classification of biological data is one of the significant challenges inbioinformatics, as well for protein as for nucleic data. The presence of these data in hugemasses, their ambiguity and especially the high costs of the in vitro analysis in terms oftime and resources, make the use of data mining rather a necessity than a rational choice.However, the data mining techniques, which often process data under the relational format,are confronted with the inappropriate format of the biological data. Hence, an inevitablestep of pre-processing must be established.This thesis deals with the protein data preprocessing as a preparation step before theirclassification. We present motif extraction as a reliable way to address that task. The extractedmotifs are used as descriptors to encode proteins into feature vectors. This enablesthe use of known data mining classifiers which require this format. However, designing asuitable feature space, for a set of proteins, is not a trivial task.We deal with two kinds of protein data i:e:, sequences and tri-dimensional structures. In thefirst axis i:e:, protein sequences, we propose a novel encoding method that uses amino-acidsubstitution matrices to define similarity between motifs during the extraction step. Wedemonstrate the efficiency of such approach by comparing it with several encoding methods,using some classifiers. We also propose new metrics to study the robustness of some ofthese methods when perturbing the input data. These metrics allow to measure the abilityof the method to reveal any change occurring in the input data and also its ability to targetthe interesting motifs. The second axis is dedicated to 3D protein structures which are recentlyseen as graphs of amino acids. We make a brief survey on the most used graph-basedrepresentations and we propose a naïve method to help with the protein graph making. Weshow that some existing and widespread methods present remarkable weaknesses and do notreally reflect the real protein conformation. Besides, we are interested in discovering recurrentsub-structures in proteins which can give important functional and structural insights.We propose a novel algorithm to find spatial motifs from proteins. The extracted motifsmatch a well-defined shape which is proposed based on a biological basis. We compare withsequential motifs and spatial motifs of recent related works. For all our contributions, theoutcomes of the experiments confirm the efficiency of our proposed methods to representboth protein sequences and protein 3D structures in classification tasks.Software programs developed during this research work are available on my home page http://fc.isima.fr/~saidi

This research is a further step towards a crosslinguistic generalization concerning the metaphor cluster called the Event Structure Metaphor (ESM). Cognitive linguists (e.g. Lakoff 1990; 1993; Lakoff & Johnson 1980; 1999) have speculated that ESM, among other conceptual metaphors, may be a candidate for a metaphorical universal because of its universal experiential motivation.In ESM, various aspects of events, such as STATES, CHANGES, PROCESSES, ACTIONS, CAUSES, PURPOSES, DIFFICULTIES, and MEANS are systematically conceptualized in terms of the concrete concepts of space, motion, and force. This study investigates whether ESM, with its OBJECT-LOCATION duality, exists in Arabic, just as it does in English, Chinese, and Hungarian, and whether Arabic exhibits the same or different submappings as those realized in English, hence same or different patterns of metaphorical abstract reasoning. Investigating the existence of ESM in Arabic, a language from yet another linguistic family, should provide more insight into the nature of ESM and its potential universality.This study suggests that metaphor in general is central to the comprehension of abstract and complex concepts. ESM, in particular, is found to be generally manifested in Arabic as well. The notions incorporated in ESM seem to be systematically conceptualized in Arabic and English in the same way; in general, they are comprehended in terms of the concrete, image-schematic concepts of space, motion, and force. Further, the study suggests that speakers of different languages appear to have similar cognitive structures, especially at the higher, generic levels of the inheritance hierarchy. However, as conceptualizations move down the hierarchy, they may diverge crosslinguistically so as to reflect culture-specific models.The potentially universal conceptualizations are a consequence of the sensorimotor, image-schematic experience that is common to all human-beings, and which is bound to surface linguistically in the same way at the higher, generic levels. This research, therefore, strengthens earlier claims about the potential universality of ESM.<br>Department of English

Includes bibliographical references (leaves 214-223).<br>The thesis applies a social constructionist framework and Foucauldian Discourse Analysis to demonstrate that while Tsotsitaal was perceived by many respondents as a language of gangsters and criminals, evidence suggests that it is actually part of an ongoing identity construction for young, black, primarily male urban township residents in South Africa, which is performed through a subcultural style. By applying Myers-Scotton's Matrix Language Frame model to questionnaire and interview data collected in two Cape Town townships, Gugulethu and Khayelitsha, the thesis identifies the syntactic framework of Cape Town Tsotsitaal as Xhosa.

It is vital that Turkey keep abreast of developments in the world and build up its technology to become a developed country. Steel construction is one of these areas. In this context, the main purpose of this study was to define, analyze and evaluate the general characteristics of structural steel and steel construction with the purpose of throwing new light on its advantages and disadvantages. Within this framework, a literature survey was conducted on structural steel components and structures<br>and on steel construction in Turkey. Additionally, a case study was carried out on a steel office building in Ankara. In this, the T&uuml<br>rkiye Esnaf ve Sanatkar Kredi Kefalet Kooperatifleri Merkez Birligi (TESKOMB) Building was investigated in terms of the design and production criteria for steel structures and to determine problems faced during these processes. As a result of this study, the existing condition of the construction sector and the means to improve use of structural steel in Turkey were discussed more realistically.

<p>An important factor in the rise of health care costs is the structure and performance of health care markets. This is an area in which policy can be particularly effective. Health care markets are characterized by complex interactions between consumers, physicians, insurers, facilities, and government agencies. Physicians, insurers, and facilities operate under a mix of objectives and governance structures. The many varieties of objectives, and governance structures can be broadly categorized as for-profit, not-for-profit, and governmental. </p><p> In the three chapters that follow I construct a theoretical framework to analyze hospital behavior and use a 30 year panel of data on Californian hospitals to assess the validity of the models and to identify the impact of governance structure on behavior. Chapter II addresses firm objectives. I find that firms have a continuum of weighting allocations, with for-profit firms placing greater weight on profit, government firms placing greater weight on social objectives, and not-for-profit firms locating in a middle ground. All three types of governance structures display overlap in their objectives. </p><p> In Chapter III, I identify patterns in hospital entry and exit. Like most manufacturing industries, entering hospitals are significantly smaller than incumbent hospitals and exiting hospitals are significantly smaller than surviving hospitals. The patterns of entry and exit for hospitals vary systematically with both governance structure and geographic diversification. </p><p> In Chapter IV, I develop a model of hospital entry that explains heterogeneous entry size and firm survival. I find entry size to be a relatively important factor in firm survival. In general entering on a larger scale increases the probability of survival. Despite this fact many firms enter relatively small. The model that I develop resolves small entry as a rational choice for uncertain firms. </p>

Corporate finance researchers have long been puzzled by low corporate debt ratios given debt's corporate tax advantage. What makes the capital structure debate especially intriguing is that the different theories represent such different, and in some ways almost diametrically opposed, decision-making processes.

L'alliage de première génération (AM1) est un superalliage base-nickel utilisé par la Snecma pour élaborer des aubes de turbine monocristallines de géométrie complexe capables de résister aux conditions extrêmes de température et de pression. Cependant, lors du procédé de solidification, le contrôle du flux de chaleur est difficile pour des raisons de complexité de la géométrie, de la mise en grappe des pièces ou de la cinétique de solidification de l'alliage. Par conséquent, le risque de germination parasite peut avoir lieu dans le liquide surfondu. Pour comprendre l'origine de la germination parasite, il est important d'identifier avec précision la variation des isothermes dans la pièce au cours de la solidification pour localiser les zones de surfusion critiques. Pour ce faire, nous avons prédit par simulation numérique la germination et la croissance des grains au cours de la solidification. Nous avons implémenté dans le module CAFE du code Procast un algorithme de couplage permettant de tenir compte de la transformation liquide→solide dans la résolution du problème thermique. Ce couplage a permis de prédire le phénomène de recalescence qui témoigne de la germination parasite. La conversion enthalpie→température dans ce couplage tient compte de plusieurs chemins de solidification qui dépendent du taux de refroidissement à chaque nœud du maillage éléments-finis. Ces chemins de solidification sont tabulés grâce à un nouveau modèle de microségrégation conçu pour les alliages multicomposés en solidification dendritique colonnaire et équiaxe. Ce modèle est basé sur les équations de conservation de la masse totale et de la masse des solutés moyennées sur un volume représentatif. Dans ce modèle, la diffusion des espèces chimiques est contrôlée dans toutes les phases. Le modèle est aussi couplé avec un logiciel de calcul thermodynamique et un modèle de cinétique de croissance dendritique conçu pour les alliages multicomposés. Les prédictions du modèle retrouvent d'expériences menées sur l'AM1<br>AM1 is a nickel-based superalloy that Snecma relies on to elaborate single crystal turbine blades having complex geometry and high resistance to extreme conditions of temperature and pressure. However, controlling heat flux during solidification process is difficult because of many reasons such as the complex geometry, the way of clustering parts and the superalloy solidification kinetics. Consequently, stray grain nucleation can occur in the undercooling liquid. Therefore, it is important to precisely identify critical undercooled zones during solidification. To do this, a new coupling algorithm is integrated in Procast software through its CAFE module. This coupling considers liquid→solid transformation in solving thermal problem. Thus, predicted recalescence during stray grain nucleation can be observed. Enthalpy→temperature conversion is based on tabulated solidification paths depending on cooling rate computed at each Finite Element node. Solidification paths are calculated using a new microsegregation model based on total mass and solute mass conservation equations over a representative volume element. It includes both finite diffusion in phases and growth kinetics for multicomponent alloys. It is also coupled with a thermodynamic software for equilibrium computation. The microsegregation model fits experimental data provided by quenching tests on AM1 superalloy

Thesis (MTech (Nature Conservation))--Cape Peninsula University of Technology, 2010.<br>Many urban rivers are heavily engineered and no longer function naturally. The City of Cape Town has designed and implemented many stormwater and river management projects. Very little monitoring has occurred as to whether these engineering projects and remediation measures, have had a positive effect on our urban river ecosystem function. The study investigated the influence of specific engineering interventions such as the placement or rocks in stream to create weirs, gabion lining of stream channels, removal of canal walls, establishment of artificial wetlands, and approaches to urban river management, on river ecosystem function of the Keysers River, Little Lotus River, Langevlei Canal, Silvermine River, Moddergat River and Big Lotus River, as measured by specific indices including water chemistry and aquatic community structure (macroinvertebrates and diatoms).

Long-term interannual changes in richness, abundance, diversity and structure of the fish community in the temporarily open/closed East Kleinemonde Estuary, Eastern Cape, are described and the recruitment success of two estuary-dependent marine species assessed. In addition, laboratory experiments were conducted to assess the possible role of olfaction in the recruitment process of an estuary-dependent marine fish species. Multivariate analyses of the annual marine fish communites identified two distinct groups with more species recorded during years that succeeded spring (September to November) mouth opening events than in years following no mouth opening events in spring. Interannual community stability (IMD) and seriation (IMS) also increased from the ‘other’ to the ‘spring’ years. These results highlight the importance of the timing of mouth opening to the marine fish community in a temporarily open/closed estuary. This study also made use of long-term records of daily mouth state and linked them to the recruitment of distinct year-class cohorts in two spardis with contrasting lifehistory characteristics. Lithognathus lithognathus only recruited into the estuary in years when the mouth opened between late August and January. This was linked to the limited spawning season of this species and its inability to enter closed estuaries via wave overwash events. In contrast, recruitment by Rhabdosargus holubi juveniles appeared to be uninterrupted and was not determined by the seasonality of mouth opening. This species dominates the marine-spawning component of the East Kleinemonde Estuary and its success is attributed to an extended spawning season and its ability to recruit into estuaries during both overwash and open mouth conditions. Attraction of postflexion Rhabdosargus holubi larvae to estuary, surf zone and river water was also measured using a rectangular choice chamber. In two sets of experiments, conducted during peak recruitment periods, larvae from both the surf zone and estuary mouth region selected estuary water with a significantly higher frequency than sea water. Larvae collected in the mouth region showed a stronger preference for river water than those collected in the surf zone, thus suggesting that these fish are more attracted to freshwater influenced nursery areas once they have entered the estuary than those in the surf zone. Larvae collected in the marine environment also selected surf zone water with significantly higher frequencies than estuary water or offshore sea water, thus confirming the importance of the surf zone as an interim nursery area for postflexion R. holubi.

This study looks at the relationship between ownership structure, monitoring and firm performance. The research employed the agency theory hypothesised by Jensen and Meckling (1976) from the view of contractual relationships among various parties involved within a company. It presents a longitudinal study of the 161 non- financial publicly listed companies in the Jakarta Stock Exchange between 1994- 2000. This design enables a researcher not only to examine the effects of various governance variables on corporate performance, but also to examine the extent to which such relationships vary with changes in the general economic environment. This study reveals that only a small proportion of private-domestic Indonesian firms have a widely dispersed ownership structure. Viewed from the standpoint of traditional agency theory, the separation of ownership and control seems to work differently in Indonesia. In this country the agency problem is not between the owners and the managers, as in Anglo-Saxon countries, but may be between “strong” controlling shareholders and “weak” minority owners. The findings suggest a strong association between degrees of ownership concentration, owner involvement in supervisory/management board and the existence of family business groups. These factors are interdependent, and each of them relates cohesively to the others within the organisation. In this regard, the collectivism and higher power distance value dimensions that are dominant in Indonesian society also heighten such relationships. Inappropriate institutional, law and legal enforcement provide the means for the controlling shareholders to continue these practices, which insulate them from external interference, monitoring and supervision.<br>Taken together, these findings support the view that national cultural features have a profound effect on the structure of national economies. The evidence corroborates the uniqueness of corporate governance practices in Indonesia, and the findings support the supremacy of controlling shareholders Further to the growing debate on the costs and benefits of controlling shareholders, the empirical findings of this study reveal that these shareholders are the source of the corporate governance problem rather than solution. In short, the most basic factor which inhibits the effectiveness of corporate governance implementation in Indonesia is the existence of powerful large shareholdings in the hands of a family. Governance reform, therefore, should address the corporate system by seeking to reduce the supremacy of these shareholders, and at the same time empower the other stakeholders. The findings also support the view of both the co-evolutionary and path-dependency theories in regard to factors that determine the pattern of ownership structure. The development of firms in Indonesia follows the path-dependence structure and, during this process, the firms’ environments will interact with and operate endogenous responses for environmental change. Such exogenous and endogenous forces shape the environment and trigger organisations to adapt in different ways so that they are able to survive.<br>Thus, one would expect there to be different corporate governance systems within each country and any effort towards reforming such systems should consider factors specific to that country. This implies that governance reforms should be fully compatible with a country’s national culture, institutional, legal and business systems. Other variables, such as informal norms (social norms and cultural beliefs) and the political environment in a country should also be considered in the design of these reforms.

This thesis examines the determinants of capital structure in the MENA coun- tries. The main interest is to investigate both financial firms specially banks and non-financial firms. This study test the main theories of capital structure, namely: trade off theory and pecking order theory. The countries included in this thesis are Saudi Arabia, United Arab Emirates (Include both Abo-Dhabi and Dubai stock indexes), Bahrain, Qatar, Kuwait, Oman, Egypt, Morocco, Tunisia, Palestine and Jor- dan. The characteristics it covers as suggested by previous literature are tangibility, profitability, risk, debt tax shield, growth, dividends,size, cash flow and liquidity. It will also investigate the effect of the industry, credit rating and ownership structure on the capital structure This study also investigates the determinants of capital structure in Islamic and conventional banks. This is one of the first attempts to empirically examine the determinants of capital structure in Islamic and conventional banks in general and in MENA countries in particular. This study fills the gap in this important area of research and can provide a base for future research on capital structure in Islamic banks. This thesis use different models to test the capital structure and these are Panel data models (OLS, Fixed, and Random); Tobit and Dynamical model (Arellano-Bover Blundell-Bond), Structural Equation Modeling (SEM) and Generalised Regression Neural Networks (GRNN). The results suggest that the three methods used in this study lead to similar re- sults with a few exceptions in some countries. This thesis finds that the relation between leverage and the determinants of capital structure is different when using the market or the book leverage. It also finds that the determinants of capital struc- ture between the MENA countries are different. For example, profitability attribute relation with leverage follow the trade-off theory in some countries and follow the picking order theory in other countries. Also, liquidity is significant in all the countries in the sample and have a negative relation to leverage. In addition, tangibility is found to have a mixed results with some countries following the trade-off theory and other countries which follow the trade-off theory but overall it is a key determinant of capital structure. Additionally, the findings show that although that the majority of firms in the MENA countries don’t pay dividends the relation between the long term debt and leverage is negative in all the countries in the sample. The growth opportunities have a negative relation in Bahrain, Egypt, Jordan, Kuwait, Morocco, Palestine, Qatar and Tunisia but positive in rest of the countries. The cash flow attribute have a negative relation with leverage in all the countries in the sample except Saudi Arabia and Qatar when using the short and long term debt. Furthermore, the ownership variable is expected to have a negative relation when the ultimate owner is an institution. The results show that overall when there is an ultimate owner the leverage will have a negative relation. Suggesting that ultimate owners will force managers to keep a low debt in firms capital structure. This PhD also attempt to investigate the capital structure in banks within the MENA countries. A special focus is on the differences between the Islamic banks and conventional banks capital structure. First, the findings show that the banks follow the same determinants of capital structure as non-financial firms and that regulations are not the main determinant of capital structure in banks. Then, This study show that there is a difference in capital structure of Islamic banks in com- parison with conventional banks. The findings for the dividends variable show that Islamic banks do not follow the pecking order theory but conventional banks don’t. The results of the size variable show that when Islamic banks are large they use less debt in their capital structure. Growth variable show mixed results depending on the use of book or market leverage. Ownership structure show that when there is an ultimate owner leverage increase which is the reverse of the relation in the non-financial firms. The age variable is negative in relation to the book leverage and positive with the market leverage. Also, credit rating relation is different between the two banks, as it is positive with the conventional banks and negative with Islamic banks. Therefore, this study conclude that the main capital structure theories are applicable to MENA countries. Also indicate that Islamic banks have a different capital structure to conventional banks.

<p> Patients and care providers fail to embrace the quality-driven relationships that were once part of the clinical consultation. To improve what some have referred to as a dampened relationship social scientists and medical professionals are pursuing a &lsquo;patient-centered&rsquo; model where healthcare is delivered in ways that are &ldquo;respectful and responsive to individual patient preferences, needs, and values&rdquo; (Institute of Medicine 2001:6). The model sets standards for identifying and responding to patient concerns regarding illness and treatment, and cherishes the benefits of shared decision-making and responsibility (Epstein 2000). Undoubtedly, this model works best when the patient&rsquo;s interest and values are central to the delivery of care.</p><p> A sample survey of 94 patients seeking treatment at an urban, hospital-based primary care clinic, are analyzed to answer three separate, but fundamental questions: 1) Is there a significant association between components of cultural capital (marital status and/or education) and patient-centered events? 2) Does the presence of any of these patient-centered events associate itself with a patient&rsquo;s overall experience? And 3) is there a significant association between components of cultural capital and overall patient experience? I hypothesize that marital status and/or education are directly associated with the presence of patient-centered events, that the presence of any one patient centered event is positively correlated with the overall clinical experience, and that a patients overall experience is directly associated with marital status and/or education.</p>

The primary intention of this work is to provide a starting point for a realisation of an electronic antenatal health record in Norway. Furthermore, the ambition was to conduction an evaluation into the potential for using archetypes for representation of structured clinical information in antenatal health care in Norway. Focus of work has been to investigate former projects in electronic solutions for antenatal health records, to gain knowledge of earlier practical experiences regarding development of archetypes and finally how lessons learnt in both can be applicable and utilised in the development of an electronic antenatal health care record in Norway. To answer these questions a qualitative case study has been performed including a literature review and interviews with informants acting within antenatal health care. As a proof-of-concept for direct reuse of formerly developed archetypes, candidate archetypes have been translated and a template has been designed. In addition all candidate archetypes have been evaluated as to clinical content coverage as regards Norwegian requirements, as well as thoroughly assessed utilising published Archetype Quality Requirements. Through this qualitative case study I have learnt the importance of involving all stakeholders as early as possible in development projects in general as in archetype development specifically. It is also important to sustain stakeholder involvement throughout the development cycle to ensure that the interests of all stakeholders are met. The in-depth validation of clinical content in candidate archetypes shows that Norwegian requirements for clinical content in antenatal health care records are met. Furthermore, the in depth validation of the quality of archetypes has resulted in significant findings for Norwegian stakeholders in antenatal health care; a thorough investigation and clarification process regarding intended use of an electronic antenatal health care record has to be initiated and concluded before development activities can commence. The need for stakeholder inclusion in a development project is also identified for antenatal health records. The identification of clinical content provided by the present project can be seen as a first step in the development of a Norwegian antenatal health record. There has also been identified significant findings regarding how translation of archetypes can be facilitated; by establishing a demonstration archetype including most commonly utilised terms in archetypes, in order to secure consistent translations with good quality in all archetypes. Finally, the in-depth evaluation regarding the metadata quality in archetypes has provided significant results with proposals for additions, specifications and needed alterations of the Archetype Quality Requirements that are published by Kalra et al (2012). To my knowledge, no other project has utilised and thoroughly evaluated these quality requirements.

In an industry plagued by underinvestment and unrest, the emergence of the publicly financed MyCiTi Bus Rapid Transit system has structurally altered the market structure of Cape Town road public transport. Due to the heavy dependence of its rollout on subsidised operating support, and the geographies it has targeted, the distribution of subsidy benefits between households in the city has changed. In this context, this investigation looks to address the question: "Is Cape Town's road public transport affordable, and is subsidised operating support well targeted at poor households?" To do so, the paper evaluates the impact of the industry transition on transport affordability and subsidy distribution with the use of a best practice systematic framework. Revealed in the affordability analysis is that Cape Town road public transport remains unaffordable for the lower quartile of the household income distribution - a finding exacerbated by Cape Town's racial economic geographies. On top of this, distribution analysis shows the significant and regressive impact of the industry transition on the distributional consequences of Cape Town road public transport subsidisation. The central premise of this paper is that this evidence warrants the need to investigate alternative subsidy frameworks. Framed by Cape Town's underlying mobility needs and road public transport market structure, this paper designs and simulates the distributional consequences of an alternative subsidy. The simulation reveals that the regressive impact of the transition can be controlled, and the overall distribution improved, by deriving the subsidy framework by a set of demand-side variables. Rather than being viewed as the complete solution, the paper concludes that this simulation signals the need for follow-up research to validate the findings, and to explore the political and operational feasibility of a demand-side subsidy orientation more thoroughly.

Thesis (MScConEcol (Conservation Ecology and Entomology))--University of Stellenbosch, 2011.<br>ENGLISH ABSTRACT: Heuweltjies are below ground termitaria found along the west coast and the south-western and -eastern Cape. They traversing different climates, soil and vegetation types within the Succulent Karoo and Fynbos biomes. From a birds eye view, heuweltjies appear as near-circular landscape features, demonstrating clear difference in vegetation structure to their surroundings. A study of aspects of the structure and function of heuweltjies, mima-like mounds of south-western South Africa was undertaken. The main aim of the study was to investigate topsoil properties and processes and vegetation structure and the ecophysiology of plants growing on these mounds, and compare it to areas off these patches. Four study sites across a rainfall gradient were chosen for soil and vegetation studies (two within the Succulent Karoo and two at the Fynbos biome). Ten sampling sites on heuweltjies and 10 off heuweltjie (interpatch) were chosen at each study site for these analyses. Soils samples from the top 10 cm were analysed for total nitrogen (N) and carbon (C) content, phosphorus (P) concentrations, particle-size distributions, pH and electrical conductivity (related to salinity). Soil biogeochemistry studies (i.e. potential N mineralization, potential soil respiration and phosphatase activity) were also done in the laboratory. In the field, the cover of soil cryptogams, selected plant growth forms and selected physical variables at each site, on and off heuweltjies, were estimated on 1m2 grids. Two of the study sites, one in the Succulent Karoo and one in Fynbos, were chosen for field measurements of stomatal conductance, predawn and midday xylem water potentials of two growth forms (deciduous and evergreen non-succulent shrubs) at selected times in the duration of the study. Leaf samples were taken to make once-off measurements of specific leaf area, C and N isotope compositions (δ13C, δ15N), and foliar N content. Furthermore, a fertilization experiment that has been running at the Tierberg Karoo Research Centre (Succulent Karoo) since 1997, where 10g m-2 of N have been added to interpatch vegetation twice annually, was included in the stomatal conductance and xylem water potential studies. The aim of including the fertilization experiment was to ascertain whether interpatch vegetation will eventually resemble heuweltjie vegetation in ecophysiology following N fertilization. Soil water probes were inserted, 10 cm deep, on one on heuweltjie and one off heuweltjie site for the long-term estimation of gravimetric water content and temperature at the Tierberg Karoo Research Centre. Heuweltjie soils were found to be hotspots for nutrients and biogeochemical activity. They had elevated levels of total % C, % N and available P (mg kg-1) compared to surrounding interpatch soils. pH and electrical conductivity (μS cm-1) of these soils were also high compared to interpatch areas. Heuweltjie soils have higher silt content and retain more water, and for a longer period following a rainstorm. Potential soil respiration, potential N mineralization and alkaline and acid phosphatase activity were generally higher on heuweltjies.Cover of the selected plant growth forms differed little between heuweltjies and the surrounding vegetation but site differences were observed. Heuweltjies differed from interpatches in the cover of soil cryptogams, with higher cover of mosses and lower cover of lichens on mounds. There was higher cover of plant litter and termite frass on the heuweltjies.There was a decrease in soil available P and increase in non-succulent shrub cover from low to high rainfall areas. On the other hand no significant differences were found in the xylem water potential of interpatch and heuweltjie plants at either of the study sites. At the Tierberg Karoo Research, stomatal conductance of interpatch plants was higher and water use efficiency (δ13C) lower compared to that of heuweltjie plants suggesting some level of water stress for heuweltjie plants at this site. Here, heuweltjie plants also had higher foliar N, lower C/N ratio values, signs of high photosynthetic potential and highly decomposable litter and higher δ15N. At Jonaskop, stomatal conductance and water use efficiency did not differ between heuweltjies and interpatch plants. There were also no differences in foliar N concentrations, C/N ratios and δ15N between heuweltjie and interpatch plants at this site. Plants growing in high N plots (the fertilizer plots) had higher xylem water potential and more variable stomatal conductance than those growing in control plots. The results of this study have shown heuweltjies to be hotspots for nutrients and biogeochemical cycling, and given enough water, will be ideal patches for plant growth. In the Succulent Karoo, high salinity (and finer textured soils) on the heuweltjies may contribute to water stress during dry periods, and together with disturbance, provide bottom-up controls on plant physiology, and ultimately, vegetation structure. In the Fynbos, plants may be limited by nutrients on heuweltjies, possibly because of increased interspecific competition, while increased rainfall may also lead to more nutrients leaching from the topsoils. The results presented are especially relevant to restoration programs, and may shed some light on restoration trajectories after overgrazing, cultivation and mining activities.<br>AFRIKAANSE OPSOMMING: Heuweltjies is ondergrondse termitaria wat langs die weskus, die suid-wes en oos Kaap van Suid Afrika voorkom. Hulle kom voor onder verskillende klimaatstreke, grondtipes en planttipes wat binne die Sukkulente Karoo en Fynbos biome voorkom. Vanuit die lug uitgesien, verskyn heuweltjies as sirkelvormige landskapseienskappe, wat duidelike verskille in plant struktuur en die omringende omgewing demonstreer. ʼn Studie van aspekte van struktuur enfunksie van ʼn heuweltjies, mima-agtige hope vansuidwestelike Suid-Afrikais onderneem. Die hoofdoel van die studie was om die eienskappe van oppervlakgrondeen -prosesse, plant struktuur, en die ekofisiologie van plante wat op heuweltjies groei te ondersoek, en dit te vergelyk met areas af van hierdie kolle. Vier studieareas wat oor „n reënvalgradient strek is gekies vir grond en plantegroei studies (twee binne die Sukkulente Karoo en twee binne die Fynbos biome). Tien monsterareas op heuweltjies en 10 af van heuweltjies (omringende areas) is gekies binne elke studiearea vir die bogenoemde analises. Grondmonsters van die boonste 10 cm van die grond is geneem en geanalieseer vir totale stikstof (N) en koolstof (C), fosfor (P) konsentrasies, gronddeeltjiegrootte, pH, en elektriese geleidingsvermoë, (hou verband met soutgehalte). Grond biogeochemie studies (d.i. potensiële stikstof mineralisasie, potensiële grond respirasie en fosfatase aktiwiteit) is ook in die laboratorium uitgevoer. In die veld was die dekking van grond kriptogame, geselekteerde plant groeivorms en fisiese veranderlikes by elke lokaliteit, beide op en van heuweltjies op 1m2vierkante bereken. Twee studie lokaliteite, een in die Sukkulent Karoo en een in die Fynbos, is gekies vir veld metings van huidmondjiegeleiding, voor dagbreek en middag xileem potensiale van twee groei vorms (bladwisselende en immergroen nie-sukkulente struike) op geselekteerde tye gedurende die studie. Blaarmonsters is geneem om eenmalige metings te maak van die spesifieke blaararea, C en N isotoop komposisies (δ13C, δ15N), en blaar N inhoud. Verder is „nbemestingseksperiment wat by die Tierberg Karoo Navorsing Sentrum (Sukkulente Karoo) loop sedert 1997, waar 10gm-2 van N jaarliks twee keer bygevoeg word by die plante wat tussen heuweltjies groei ingesluit in die stomata geleiding en xileem water potensiaal studies. Die doel van die bevrugting eksperiment was om vas te stel of die omliggende plante (af van heuweltjies) uiteindelik soos die van die heuweltjiessal lyk in terme van ekofisologie nadat dit met stikstof bemes is. Grondwater monitoreringsapparaat was ingesit (10cm diep) op een op heuweltjie en een lokaliteitaf van die heuweltjie vir die langtermyn bepaling van gravimetriese water inhoud (m3m-3) en temperatuur by die Tierberg Karoo Navorsing Sentrum. Daar is gevind dat grond op heuweltjies “skerpkolle” is vir voedingstowwe en biogeochemiese aktiwiteit. Hulle het ook verhoogte vlakke van totale %C, % N, en beskikbare P (mg kg-1) teenoor die omliggende areas om die heuweltjies. pH en elektriese geleidingsvermoë (μS cm-1) van hierdie gronde was ook hoër in vergelyking met die omliggende areas. Heuweltjie grond het „n hoër sout inhoud gehad en behou meer water vir ʼn langer periode na ʼn reënstorm. Potensiële grond respirasie, potensiële stikstof mineralisasie, en alkaliese en suur fosfatase aktiwiteit is oor die algemeen hoër op heuweltjies. Die voorkoms van die geselekteerde plant groeivorms verskil min tussen heuweltjies en die omliggende omgewing, maar verskille tussen studie areas is opgemerk. Heuweltjies het verskil van areas af van heuweltjies in die voorkoms van grond kriptogame, met ʼn hoër voorkoms van mosse en ʼn laer voorkoms van ligene op die heuweltjies. Daar was hoër voorkoms van plantafvalmateriaal en termiet uitwerpsel op die heuweltjies. Daar was ʼn afname in grond P (mg kg-1) en ʼn toename in nie-sukkulente struik bedekking van lae tot hoë reënval areas. Daar was geen verskil in die xileem water potensiaal van plante op die heuweltjies of af van die heuweltjies by enige van die studie lokaliteite nie. By die Tierberg Karoo Navorsing Sentrum was huidmondjie geleiding van plant in die areas tussen heuweltjies hoër en die water gebruik doeltreffendheid (δ13C) laer in vergelyking met die van die heuweltjie plante, wat op„n sekere vlak waterstres dui in heuweltjie plante by hierdie studiearea. Hier het heuweltjie plante ook hoër blaar N, laer C/N waardes, tekens van hoër fotosintetiese potensiaal en hoogs afbreekbare afvalmaterialgehad asook hoër δ15N. By Jonaskop het huidmondjie geleiding en water gebruik doeltreffendheid nie verskil tussen heuweltjie en omliggende plante nie. Daar was ook geen verskille in blaar N konsentrasies, C/N verhoudings en δ15N tussen heuweltjie en omliggende plante by hierdiestudiearea nie. Plante wat groei in hoë stikstof plotte, het hoër xileem water potensiaal (minder stres) en meer veranderlike stomatal geleiding as die plante wat in die kontrole plotte groei. Die resultate van die studie het getoon dat heuweltjies “skerpkolle” is van voedingstowwe en biogeochemiese siklusse, en gegewe genoeg grondwater, sal ideale areas wees vir die groei van plante. In die Sukkulente Karoodra hoë soutgehalte (en fyner grond teksture) op die heuweltjies by tot water stres gedurende droë tye, en saam met versteurings dra dit by tot grond tot plant kontrole op plantfisiologie, en uiteindelik plant gemeenskapsstruktuur. In die Fynbos word plante op die heuweltjies beperk deur te min voedingstowwe, moontlik omdat daar ʼn toename is in intraspesifieke kompetisie, terwyl hoër reenvalkan lei tot hoër loging van voedingstowwe vanuit die bogrond. Die resultate wat hier gerapporteer word is veral relevant vir restourasieprogramme, en mag lig werp op restourasie trajekte na oorbeweiding, aanplanting van gewasse en mynbou-aktiwiteite.

Le développement des structures de grains se formant durant les procédés de soudage par fusion a un large impact sur les propriétés et la résistance mécaniques des assemblages. Des défauts, tels que la fissuration à chaud, sont aussi liés à la texturation de grains propre à l'étape de solidification. La simulation directe du développement tri-dimensionnelle (3D) des structures de grains dans ces procédés, à l'échelle industrielle, est rarement proposée. Dans ce travail, une modélisation couplée 3D Automate Cellulaire (CA) - Eléments Finis (FE) est proposée pour prédire la formation des structures de grains dans les procédés de soudage multipasses GTAW (Gas Metal Arc Welding) et GMAW (Gas Metal Arc Welding). A l'échelle macroscopique, la modélisation FE permet la résolution des équations de conservation de la masse, de l'énergie et de la quantité de mouvement pour l'ensemble du domaine en s'appuyant sur un maillage adaptatif. Pour le procédé GMAW avec apport de matière, le modèle FE est enrichi et développé dans une approche level set (LS) afin de modéliser l'évolution de l'interface métal / air due au développement du cordon de soudure. Le domaine FE contient ainsi la pièce étudiée et l'air environnant dans lequel le cordon se développe. Les calculs FE sont couplés avec l'approche CA utilisée pour modéliser le développement de la structure de grains. Un maillage fixe ('maillage CA') est superposé au maillage adaptatif FE ('maillage FE'). Les champs macroscopiques propres au maillage FE sont ainsi interpolés entre le maillage adaptatif FE et le maillage fixe CA. Une nouvelle stratégie d'allocation / désallocation de la grille de cellules CA est ensuite utilisée basée sur l'allocation / désallocation des éléments du maillage CA. La grille CA est constituée d'un ensemble régulier de cellules cubiques superposées au domaine soudée. A l'échelle micro-, la grille est utilisée afin de simuler les étapes de fusion et solidification, à la frontière entre le domaine pâteux et le bain liquide, durant le processus de soudage. Les évolutions de températures des cellules sont définies par interpolation du maillage CA. Un couplage du modèle avec les chemins de solidification et les évolutions enthalpiques tabulés est aussi implémenté, permettant de suivre la thermique et les évolutions de fractions de phase propre à l'évolution du procédé. Avec de réduire les temps de calcul et la quantité de mémoire informatique nécessaire à ces simulations, une optimisation des maillages FE/CA et des tailles de cellules CA est proposée pour les deux approches FE et CA. La modélisation 3D proposée est appliquée à la simulation de la formation des structures de solidification formées durant le soudage GTAW et GMAW multipasses de pièces d'acier inoxydables de nuances UR 2202. Dans le procédé GTAW, l'influence de l'évolution des structures de grains selon les paramètres procédés est étudiée. L'orientation normale des grains avec l'augmentation de la vitesse de soudage est montrée. Dans le procédé GMAW, la modélisation permet de simuler la refusion et la croissance des grains des couches successives. De manière générale, les structures de grains prédites montrent qualitativement les évolutions attendues présentées dans la littérature.