Large catfishes (Clarias gariepinus & Clarias ngamensis) are not exploited commercially in the Okavango Delta, Botswana. They however constitute a large proportion of the gill net fishery catch (23 %) albeit as by-catch, coming second after cichlids (70 %). Monthly experimetal gill net sampling over 8 years showed that C. gariepinus was the most abundant species in the Okavango Delta by mass making up 37 % of the catch composition by fresh weight. Despite the relatively high abundance of C. gariepinus in the Okavango Delta, its status has never been fully assessed. For this reason, this study aimed to assess the status of C. gariepinus in the Okavango Delta with the particular goal to determine if the species could support a directed commercial gill net fishery. Investigation of the effects of the flood pulse on abundance of C. gariepinus showed that variability in water levels was the major driver of population abundance for this species. Three biological variables: (1) catch per unit effort (CPUE); (2) % catch composition and (3) Shannon's diversity index (H') exhibited a negative and significant relationship with the flood index within a year. The variation in these variables was statistically significant between months. There was a weak positive relationship between water levels and the biological variables between years suggesting increase in productivity of the system at high water levels without a lag period. Age and growth were determined using sectioned otoliths. Edge analysis showed that growth zone deposition occurred during the drawdown period in summer when water temperature and day length were increasing. The maximum recorded age was 15 years. Growth of this species was best described by the linear models (y = 21.50x + 427.39 mm LT; r² = 0.35) for females and (y = 23.79x + 440.83 mm LT; r² = 0.38) for males. The von Bertalanffy growth model described growth as Lt = 10000(1- exp(-0.002(t + 18.07))) mm LT for combined sexes Lt = 10000(1- exp( -0.002(t + 18.50))) mm LT , for females and Lt =908(1-exp(-0.076(t+7.95)))mmLT for males. Age at 50 % maturity was attained in the first year of life. Spawning occurred throughout the year with an apparent peak between November and April. The mean total annual mortality rate (Z) was 0.25 per year. The mean annual natural mortality rate (M) was 0.20 per year and fishing mortality (F) was calculated at 0.05 per year. The life history strategy of C. gariepinus was in between the periodic and opportunistic strategies. Therefore management of this species should be aimed at maintaining a healthy adult population and age structure. Since a large portion of the Okavango Delta is already protected and most other parts are also inaccessible to fishers there are enough spatial refugia for the species and the status quo should be maintained. Under this scenario, there is no need for regulation of the current mesh sizes because the species is harvested after maturity and replenishment of exploited populations will always occur from other parts of the system. Per recruit analyses indicate that the current fishing mortality maintains spawner biomass at levels greater than 90 % of pristine levels. Therefore a commercial fishery may be established using mesh 93 mm to maximize yield with a rotational harvesting strategy. Close monitoring is essential to ensure that re-colonization of overexploited habitats does indeed occur. Recreational angling and commercial gill net fishing need to be separated on a spatial and temporal scale during the feeding run to minimize potential conflicts.

Abstract Oversampling data converters based on Delta-Sigma modulation are a popular solution for modern high-resolution applications. In the design of digital-to-analog or analog-to-digital Delta-sigma converters there are common obstacles due to the difficulties on predicting and verifying their performance. Being a highly nonlinear system, a Delta-Sigma modulator’s (DSM) quantization noise and therefore the spurious tones are difficult to analyze and predict. Multi-bit DACs can be used to improve the performance and linearize the behavior of DSMs. However, this will give rise to the need for linearizing the multi-bit DAC. A popular DAC linearization method, data weighted averaging (DWA) shapes the DAC mismatch noise spectrum. There are many variants of DWA, for low-pass and band-pass DSMs. This thesis proposes a generalization which integrates a few published variants into one, broader DWA scheme. The generalization enables expanding the tone-suppression studies into a larger concept. The performance of one- or multibit DSMs is usually verified by simulations. This thesis proposes a simulation-based qualification (characterization) method that can be used to repeatedly verify and compare the performance of multibit DSM with a DAC mismatch shaping or scrambling scheme. The last contribution of this thesis is a very simple model for tonal behavior. The model enables accurate prediction of spurious tones from both DSMs and DWA-DACs. The model emulates the tone behavior by its true birth-mechanism: frequency modulation. The proposed prediction model for tone-behavior can be used for developing new tone-cancelation methods. Based on the model, a DWA linearization method is also proposed. / Tiivistelmä Delta-Sigma modulaatio on suosituin tekniikka ylinäytteistävissä datan muuntimissa. Riippumatta toteutustarkoituksesta (analogia-digitaali- tai digitaali-analogia-muunnos), Delta-Sigma (DS) modulaatiossa on yleisesti tunnettuja käyttäytymisen ennustamiseen liittyviä ongelmia. Nämä ongelmat ovat peräisin modulaattorin luontaisesta epälineaarisuudesta: DS-muunnin on nimittäin vahvasti epälineaarinen takaisinkytketty systeemi, jonka harhatoistojen ennustaminen ja analysointi on erittäin hankalaa. Yksibittisestä monibittiseen DS-muuntimeen siirryttäessä muuntimen suorituskyky paranee, ja muuntimen kohinakäyttäytyminen on lineaarisempaa. Tämä kuitenkin kostautuu tarpeena linearisoida DS-muuntimen digitaali-analogia (D/A) muunnin. Tällä hetkellä tunnetuin linearisointimenetelmä on nimeltään DWA (data weighted averaging) algoritmi. Tässä työssä DWA:lle ja sen lukuisille varianteille esitellään eräänlainen yleistys, jonka avulla algoritmia voidaan soveltaa sekä alipäästö- että kaistanpäästö-DS-muuntimelle. Kuten tunnettua, DS-modulaattorin analyyttinen tarkastelu on raskasta. Yksi- ja monibittisten DS-muuntimien suunnitellun käyttäytymisen varmistaminen tapahtuukin yleensä simulointien avulla. Työssä esitetään simulointiperiaate, jolla voidaan kvalifioida (karakterisoida) monibittinen DS-muunnin. Tarkemmin, kvalifioinnin kohteena on DWA:n kaltaiset D/A -muuntimien linearisointimentelmät. Kyseessä on pyrkimys ennen kaikkea toistettavaan menetelmään, jolla eri menetelmiä voidaan verrata nopeasti ja luotettavasti. Tämän väitöstyön viimeinen kontribuutio on matemaattinen malli harhatoistojen syntymekanismille. Mallilla sekä DS-muunnoksen että DWA-D/A -muunnokseen liittyvät harhatoistot voidaan ennustaa tarkasti. Harhatoistot mallinnetaan yksinkertaisella havaintoihin perustuvalla FM-modulaatiokaavalla. Syntymekanismin mallinnus mahdollistaa DS-muuntimien ennustettavuuden ja täten auttaa harhatoiston kumoamismenetelmien kehittämistä. Työssä esitetään yksi matemaattisen mallin avulla kehitetty DWA-D/A -muunnoksen linearisointimenetelmä.

This thesis examines the role of environmental non-government organizations in relation to the role and responsibility of government for wetland conservation in British Columbia. The role of a small community-based environmental organization called the Burns Bog Conservation Society in decisions about Burns Bog, a large privately-owned wetland located in the Lower Mainland, is analyzed. Drawing from a broad range of literature on environmentalism and conservation, the thesis begins with an historical account of the environmental movement, giving a broad view of environmental conservation and the role of environmental organizations. A typology of roles and analytical framework is subsequently derived from a study of environmental non-government organizations involved in managing water resources in British Columbia's Fraser River Basin. Three main roles, advocacy, supplemental and transformative, are discussed as they relate to activities prior to and during the Burns Bog Analysis, a provincially established land use study of Burns Bog. This research found that a small community-based environmental organization, through advocacy, can ensure that ecological integrity is not neglected as a result of poor planning and decision-making. The case study demonstrates that a small environmental organization can pressure governments to broaden their view of land-use and environmental issues, assuring more informed decision-making. An environmental organization can also supplement the regular roles and responsibilities of government, first by supplying a service that government is unable or unwilling to provide, and second by participating in and legitimizing consensus-based decision-making processes. The case study demonstrates how a small environmental organization can provide and review information and participate in creating options and solutions in land-use decisions. Finally, an environmental organization can influence, overtime, the fundamental restructuring of government planning and decision-making processes and transform the way society thinks and operates. The thesis concludes that environmental non-government organizations have an important role to play in ensuring the recognition and conservation of British Columbia's wetlands in government planning and decision-making processes; in informing and educating government and the public about ecological systems and their values; and in counter-balancing strong economic, political and development interests. / Applied Science, Faculty of / Community and Regional Planning (SCARP), School of / Graduate

La littérature du XIXe siècle se tourne vers l’enfant, avec des œuvres dont ce dernier est le héros et le destinataire, et ses représentants s’engagent à servir le besoin d’instruire et de divertir en même temps. La comtesse de Ségur et Pinélopi S. Delta, pour des raisons différentes chacune, écrivent pour des enfants et pour la jeunesse. La première présente la vie quotidienne des enfants sous le Second Empire, à travers l'idéologie dominante de l'époque où prédominent les principes de l'Eglise catholique. La seconde, cinquante ans plus tard, ne dissimule pas ses intentions d'écrire des œuvres axées sur l'idée d'une renaissance politique, culturelle et territoriale de la Grèce. Engagée dans le mouvement du démoticisme, elle espère inspirer la fierté d'être Grec en ayant recours au passé glorieux de Byzance et plus spécialement aux pages de l'histoire à l'époque du règne de Basile II le Bulgaroctone. Où se rencontrent les deux femmes, quels sont les principes qui se recoupent, quelle place et quel rôle occupent les punitions et autres contraintes dans leurs œuvres, et dans quelle perspective? Quel point ont en commun les enfants de la vie tranquille de tous les jours et les jeunes gens qui partent en mission secrète durant les conflits gréco-bulgares? Quels rapports se développent entre eux et les adultes-modèles éducatifs qui contrôlent leur vie et leur éducation ? Avec pour point de départ les livres des deux écrivains, nous recourons à la réalité historique, sociale, éducative des sociétés grecque et française afin de mieux comprendre l'œuvre mais aussi la personnalité de ces deux éminentes femmes de lettres, qui sont devenues un point de référence pour leur époque et pour la littérature enfantine d'un point de vue diachronique. / The literature of the nineteenth century aims to the childhood creating books for children with children as little heroes. The representatives of this kind of literature engage their efforts to serve the necessity of educating through amusement. Comtesse de Segur and Pinelopi S. Delta, each of them for their own different reasons, write books for children and adolescents. The first presents the everyday life of the children under the Second Empire, throughout the prevalent principles of the Catholic Church’s ideology. The second, fifty years later, does not hide her intentions to write books focused on the idea of a political, cultural and territorial renaissance of Greece. Engaged in the movement of demoticisme and seeking her themes from the glorious pages of the Byzantine Empire and more specifically at the era of Basil II the Boulgaroctone, she hopes to awake the pride of being Greek as well as put the Greek people in a state of alertness. Where do the two ladies meet each other in their pathway of creativity, which of their principles match? Questions like what role do punishments and other kinds of constraints play in their books, what in common have the children of the tranquil life with the young persons who leave on secret missions during the Greek-bulgarian conflicts or which relations are being developed between them and the adults- educative models that control their life and their education we tried to deal with in this research. Starting from the books of the two writers, we run to the historical, social and educative reality of the Greek and French society in order to understand the work as well as the personalities of those two eminent ladies, who marked their time and have been keeping a remarkable place in the children’s literature in a diachronic basis.

The development of market socialism in China has contributed to a spatial economic transformation characterized, among other things, by the apparent capacity to rapidly industrialize without transferring large numbers of people into big cities. The most striking element of this transformation has been the phenomenal growth and spatial proliferation of industries in particular areas of the Chinese countryside. The conventional wisdom of existing theories of development, industrialization, and urbanization does not adequately explain the emergence of these relatively productive regions. This thesis examines the key patterns and underlying processes and mechanisms which must be accommodated in a new analytical and conceptual framework for understanding rural transformation and the wider spatial economic restructuring in China's lower Yangzi delta. The overall objective is to explore the theoretical implications of the local character of regional change through an evaluation of a hypothetical model of mega-urbanization. The model situates the emergence and specific patterns of industrial production within a complex network of interactions and interrelationships embedded in overlapping administrative and institutional structures which are themselves largely tied to the circumstances of particular places. The resulting investigations are based upon an analysis of regional and local level statistical and other documentary sources, numerous interviews, field observations, and a survey questionnaire of rural enterprises which was part of a detailed case study of one county level area in the lower Yangzi delta. Two central findings are revealed. First, the patterns and underlying processes and mechanisms of regional development in the delta are fundamentally linked to intensely localized exigencies and opportunities within the wider Chinese space economy. Second, external economies, the dynamics of agglomeration, and the role of large cities and other exogenous forces, while significant, were less important in the delta than were endogenous forces. The details of these findings are incorporated into a revised model of mega-urbanization which highlights the critical processes and mechanisms which underlie the patterns observed, what establishes these processes and mechanisms, and what stabilizes and reproduces them. The thesis concludes by suggesting an agenda for the creation of appropriate planning and management responses for the lower Yangzi delta region. / Arts, Faculty of / Geography, Department of / Graduate

Nos processos de fabricação de parafusos, a fosfatização é necessária para servir de ancoradouro aos lubrificantes, e outros redutores de atrito, por facilitarem o processo de deformação a frio. No entanto, antes do início do tratamento térmico de têmpera e revenimento, é importante que o banho de desfosfatização seja eficiente para impedir que, durante a austenitização, o fósforo residual presente na superfície do parafuso se difunda para o aço e forme uma fase frágil, rica em fósforo, denominada ferrita delta (&#948). Acredita-se que esta fase, uma vez presente, promove não apenas a diminuição da vida em fadiga mas, também, a fragilização do parafuso. Neste sentido, o presente trabalho objetivou comprovar a influência negativa dessa fase, devidamente caracterizada por MEV, EDS e análise fractográfica, quanto ao desempenho à fadiga, através da comparação das curvas S-N em corpos de prova com e sem ferrita &#948. Os resultados obtidos claramente evidenciaram que a presença da fase &#948 promoveu uma redução de até 40% na vida em fadiga. / In the process of manufacturing bolts, a coat phosphating is required to serve as anchorage for lubricants and other friction-reducer, facilitating the cold forming process. However, before the beginning heat treatment of quenching and tempering, it is important that the alkaline bath for cleaning be efficient in order to prevent that during austenitizing, the residual phosphorus spread on the steel surface and forms a brittle phase, rich in phosphorus, called delta ferrite (&#948). In the presence of this phase, is credited with a decrease in fatigue life of the bolt and embrittlement. The intention in this work was to show the negative influence of this phase on fatigue performance, comparing the S-N curves for specimens with and without ferrite &#948. Trials have shown a reduction of up to 40% in life fatigue. The ferrite &#948 was characterized by SEM, EDS and also performed fractographic analysis.

<p>There are many real models in which unbounded solution to conservation law system occur. Most often we have some kind of delta function in the solution as a result of the accumulation of mass or some other variable. There is no general method of approaching<br />such problems with nonlinearities. This dissertation provides solutions to conservation law systems that contain division by a dependent variable, which is a problematic part when working with measures. For example, a basic model of chromatography and similar chemical processes has a division with a variable that is unbounded in some cases. The denition of the split delta shock and the general method of using it in such systems is given. Finally, the solution for the singular chromatography model is given.<br />&nbsp;</p> / <p>Postoji mnogo realnih modela u kojima se javljaju neoranicena resenja zakona odrzanja. Najcesce imamo neku vrstu delta funkcije u resenju kao posledicu nagomilavanja mase ili neke druge velicine. Ne postoji opsti metod prilaza takvim problemima sa nelinearnostima. U ovoj disertaciji su data resenja problema zakona odrzanja koja sadrze delenje zavisnom promenljivom, sto je problematican deo kod rada sa merama. Na primer, osnovni model hromatograje i slicnih hemijskih procesa ima delenje promenljivom koja je neogranicena u nekim slucajevima. Data je denicija inverza delenjog delta udarnog talasa i opsti metod primene u takvim sistemima. Na kraju je dato resenje kod modela singularne hromatograje.<br />&nbsp;</p>

Les enjeux alimentaires liés aux mutations de l’aménagement du territoire sont une question d’actualité, mais aussi source de polémique. C’est notamment le cas du bassin versant du fleuve Gianh, situé dans la Région Centre au Vietnam. En effet, depuis 1986, ce delta de zone littorale connait des mutations. La riziculture, qui emploie une grande partie de la population, constitue une soupape de sécurité contre la pénurie alimentaire. Cette région connait une croissance démographique, urbaine et économique rapides. Cela entraîne une augmentation de la demande alimentaire, alors que les zones agricoles ont tendance à disparaître. Une autre conséquence de ce changement est l’accentuation des conséquences des typhons avec la conjonction entre tempêtes, marées et crues du fleuve. Le risque s’accroît à cause de la concentration démographique dans des zones fragiles, et de la bétonisation liée à l’extension de la ville. Un problème d’insécurité alimentaire est susceptible d’apparaître dans le bassin si des densités trop fortes sont combinées avec la réduction des surfaces rizicoles et le risque. C’est pourquoi des solutions sur la gestion, la prévention et protection de l’inondation sont proposés afin d’aider les aménageurs au Vietnam pour la réduction les risques. / Food shortage related to the changes in land which is used for planning are a current issue, but also a source of controversy. This, particularly, is the case of the Gianh River watershed, located in the Central Region of Vietnam. Indeed, since 1986, this delta of littoral zone has been known for mutations. Rice farming helps to bring job to a large number of the population, is a safety valve against the food shortage because the more farmers, the more food would be produced.This region, on the other hand, is experiencing rapid demographic, urban and economic growth, as a result, it leads to an increase in the demand for food while the agricultural areas tend to be reduced and disappeared. Another effect of this change is the accentuation of the consequences of typhoons with the conjunction of storms, tides and floods of the river. The risk increases because of the demographic concentration in fragile areas, and the concreteization linked to the extension of the city. A problem of food insecurity is likely to appear in the basin if too high densities are combined with the reduction of farming areas and risks. That's why flood management, prevention and protection solutions are proposed to help developers in Vietnam to reduce mentioned risks.

Design step for Sigma-Delta ADC is introduced. Suitable solution for performance improvement of the original Sigma-Delta ADC, which meets new requirements on resolution of 16 bits and signal bandwidth 20-50 kHz is presented. Advantage of using multi-bit quantization and DEM DWA method reducing the linearity requirements of the internal feedback DAC is shown.

This project deals with implementation of a first order Sigma–Delta AD converter on the FPGA. This ADC is design for an audio signal processing. ADC is build up partially from digital blocks implemented in FPGA (programmed using VHDL) and from few analog components placed external to FPGA. Output from ADC is PCM signal. Data from ADC is created UDP datagram, which is sent to PC via network connection. Income data are received in created program, which save data to text file. This text file is processing in MATLAB.