• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 227
  • 132
  • 19
  • 16
  • 13
  • 11
  • 4
  • 4
  • 3
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 497
  • 189
  • 53
  • 44
  • 35
  • 27
  • 24
  • 24
  • 23
  • 23
  • 22
  • 22
  • 22
  • 22
  • 20
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
441

Wind energy analysis and change point analysis / Analyse de l'énergie éolienne et analyse des points de changement

Haouas, Nabiha 28 February 2015 (has links)
L’énergie éolienne, l’une des énergies renouvelables les plus compétitives, est considérée comme une solution qui remédie aux inconvénients de l’énergie fossile. Pour une meilleure gestion et exploitation de cette énergie, des prévisions de sa production s’avèrent nécessaires. Les méthodes de prévisions utilisées dans la littérature permettent uniquement une prévision de la moyenne annuelle de cette production. Certains travaux récents proposent l’utilisation du Théorème Central Limite (TCL), sous des hypothèses non classiques, pour l’estimation de la production annuelle moyenne de l’énergie éolienne ainsi que sa variance pour une seule turbine. Nous proposons dans cette thèse une extension de ces travaux à un parc éolien par relaxation de l’hypothèse de stationnarité la vitesse du vent et la production d’énergie, en supposant que ces dernières sont saisonnières. Sous cette hypothèse la qualité de la prévision annuelle s’améliore considérablement. Nous proposons aussi de prévoir la production d’énergie éolienne au cours des quatre saisons de l’année. L’utilisation du modèle fractal, nous permet de trouver une division ”naturelle” de la série de la vitesse du vent afin d’affiner l’estimation de la production éolienne en détectant les points de ruptures. Dans les deux derniers chapitres, nous donnons des outils statistiques de la détection des points de ruptures et d’estimation des modèles fractals. / The wind energy, one of the most competitive renewable energies, is considered as a solution which remedies the inconveniences of the fossil energy. For a better management and an exploitation of this energy, forecasts of its production turn out to be necessary. The methods of forecasts used in the literature allow only a forecast of the annual mean of this production. Certain recent works propose the use of the Central Limit Theorem (CLT), under not classic hypotheses, for the estimation of the mean annual production of the wind energy as well as its variance for a single turbine. We propose in this thesis, an extension of these works in a wind farm by relaxation of the hypothesis of stationarity the wind speed and the power production, supposing that the latter are seasonal. Under this hypothesis the quality of the annual forecast improves considerably. We also suggest planning the wind power production during four seasons of the year. The use of the fractal model, allows us to find a "natural" division of the series of the wind speed to refine the estimation of the wind production by detecting abrupt change points. Statistical tools of the change points detection and the estimation of fractal models are presented in the last two chapters.
442

Interações ecológicas entre plantas e animais: implicações para a conservação e restauração de uma ilha pluvial Atlântica / Ecological interactions between plants and animals: implications for the conservation and restoration of an Atlantic forest island

Fleury, Marina Huete 10 June 2009 (has links)
Os ecossistemas de ilhas, continentais ou oceânicas, são considerados os mais sensíveis à perturbação humana. A maioria das ilhas costeiras do Brasil sofreu fortes alterações na fauna e flora silvestre. A Ilha Anchieta (Ubatuba, SP) é uma Área Protegida com um longo histórico de perturbação, tendo sido amplamente desmatada no passado e sofrido a introdução de animais. Sabe-se que a fauna possui um papel chave na composição e estrutura da comunidade vegetal, favorecendo algumas espécies e prejudicando outras. Sendo assim, a perda ou alteração dos processos de interações entre animais e plantas afetam na estrutura e composição de espécies. Este estudo analisa as interações antagônicas entre planta e animais como possíveis fatores limitantes no processo de regeneração natural em três ambientes com distintos estágios sucessionais presentes na Ilha Anchieta: campo aberto (CA) e florestas ombrófilas rala (FOR) e densa (FOD). Para isso foram testados nos três ambientes os processos pós-dispersão de sementes: a predação de sementes pós-dispersas, a germinação do banco de sementes e a herbivoria. A predação de sementes apresentou forte efeito espacial (FOD>FOR>CA) e sazonal, com maiores proporções de predação de sementes no período de escassez de alimento (estação seca). Quantitativamente o banco de sementes não representa um fator limitante, porém foi composto por uma baixa diversidade de espécies lenhosas. A capacidade de germinação do banco de sementes do solo foi similar entre os ambientes florestais apresentando menor emersão de plântulas no campo aberto, provavelmente associado ao intenso escoamento superficial no local. Adicionalmente, a mortalidade de juvenis transplantados foi de 72,27%, sendo superior nas parcelas abertas aos vertebrados para todas as espécies em todos os ambientes, demonstrando um forte efeito negativo dos herbívoros vertebrados na comunidade vegetal. Sendo assim, foram detectados distintos gargalos atuando simultaneamente na regeneração natural nos três ambientes da Ilha Anchieta, sendo necessário o estabelecimento de práticas de manejo visando minimizar os efeitos abióticos no campo aberto e floresta ombrófila rala, favorecendo as interações mutualísticas e inibindo a atividade de animais antagônicos nas florestas ombrófilas rala e densa, acelerando assim o processo de regeneração natural na Ilha Anchieta. Considerar simultaneamente os obstáculos no processo de regeneração nos auxiliará a traçar práticas de restauração e recuperação de áreas degradadas mais efetivas e viáveis economicamente. / Island ecosystems, either continental or oceanic, are considered the most sensible to anthropogenic influences. Most Brazilian coastal islands have their original fauna and flora composition altered. The Anchieta Island (southeast Brazil) is a Protected Area that suffered deforestation and introduction of alien species. It is known that the fauna plays a key role in composing and structuring the vegetal community, favoring some species and harming others. Thus, the loss or change of animal-plant interactions affects the framework and composition of species. We simultaneously analyzed the antagonistic animal-plant interactions as possible limiting factors in the natural regeneration on tree successional stages of the Anchieta Island: the old fields (OF), the early secondary forest (ESF) and old growth forest (OGF). Therefore, in each habitat we are evaluating post-dispersal seed predation processes: post-dispersal seed predation, soil seed bank, and the herbivory. We found spatial (OGF>ESF>OF) and temporal effects on seed predation, with highest rates on dry season. Quantitatively, soil seed bank did not represent a limiting factor; but qualitatively, it was composed by few woody species. Our data pointed to the absence of a viable soil seed bank in the OF, probably due to an intense runoff. The forested habitats presented similar soil bank. Moreover, the total mortality of saplings was 72.27%, being higher on the unfenced treatment for all species and in all habitats, showing a very strong negative effect of vertebrate herbivores on the vegetal community. Therefore, we are detecting distinct bottlenecks acting simultaneously in the natural regeneration process in all of the successional stages of the Anchieta Island. Our results showed that management actions are required, aiming to both minimize the abiotic effects on the old fields and in the early secondary forest and to favor the mutual interactions and inhibit the activity of antagonic animals in the old growth and early secondary forests, accelerating, this way, the natural regeneration process of the Anchieta Island. Considering simultaneously the obstacles in the regeneration process will help to define restoration and recuperation procedures of degraded areas more effective and affordable.
443

Weather risk management

Cabrera, Brenda López 30 August 2010 (has links)
CAT-Bonds und Wetterderivate sind die Endprodukte eines Verbriefungprozesses, der nicht handelbare Risikofaktoren (Wetterschäden oder Naturkatastrophenschäden) in handelbare Finanzanlagen verwandelt. Als Ergebnis sind die Märkte für diese Produkte in der Regel unvollständig. Da geeignete Risikomaße in Bezug auf einen bestimmten Preis Voraussetzung sind zur Preisbestimmung, ist es notwendig den Marktpreis des Risikos (MPR), welcher ein wichtiger Parameter des zugehörigen äquivalenten Martingalmaß ist, zu berücksichtigen. Die Mehrheit der bisherigen Veröffentlichungen haben die Preise der nicht handelbaren Vermögenswerte mittels der Annahme geschätzt, dass der MPR gleich null ist. Diese Annahme verzerrt allerdings die Preise und wurde bisher noch nicht quantifiziert. Diese Doktorarbeit beschäftigt sich mit den Unterschieden zwischen dem historischen und dem risikoneutralen Verhalten der nicht handelbaren Basiswerte und gibt Einblicke in den Marktpreis für Wetterrisiko und die Wetterrisikoprämie. Diese Arbeit beginnt mit einer Darstellung der Instrumente zur Übertragung der Risiken, gefolgt von den finanziellen - statistischen Verfahren und endet mit einer Untersuchung reeller Daten, wobei der Schwerpunkt auf die implizierten Trigger-Intensitätsraten eines parametrischen CAT-Bond für Erdbeben und auf den MPR der Temperatur Derivate gelegt wird. / CAT bonds and weather derivatives are end-products of a process known as securitization that transform non-tradable (natural catastrophes or weather related) risk factors into tradable financial assets. As a result the markets for such products are typically incomplete. Since appropiate measures of the risk associated to a particular price become necessary for pricing, one essentially needs to incorporate the market price of risk (MPR), which is an important parameter of the associated equivalent martingale measure. The majority of papers so far has priced non-tradable assets assuming zero MPR, but this assumption yields biased prices and has never been quantified earlier. This thesis deals with the differences between historical and risk neutral behaviors of the non-tradable underlyings and gives insights into the behaviour of the market price of weather risk and weather risk premium. The thesis starts by introducing the risk transfering instruments, the financial - statistical techniques and ends up by examining the real data applications with particular focus on the implied trigger intensity rates of a parametric CAT bond for earthquakes and the MPR of temperature derivatives.
444

Correntes e temperaturas na quebra da plataforma continental de Cabo Frio: observações / Currents and temperatures on continental shelf break of Cabo Frio: observations

Caroli, Alexandre de 19 December 2013 (has links)
Analisamos aproximadamente três anos de dados correntográficos, em toda a coluna d\'água, e de temperatura junto ao fundo, a fim de avaliar o comportamento hidrodinâmico e termal nas proximidades da Quebra da Plataforma Continental (QPC) de Cabo Frio (CF, Rio de Janeiro, Brasil - 23° 20\'S). A Corrente do Brasil (CB) força movimentos apontando para sudoeste, paralelos à isóbata, em todos os níveis verticais, com variação sazonal das intensidades: médias máximas para o verão (58,7 cm/s) e primavera (41,4 cm/s) e mínimas para inverno (31,0 cm/s) e outono (22,8 cm/s). Foram obtidos máximos significativos de correlação entre as correntes paralelas à isóbata, em toda a coluna d\'água, e o vento na mesma direção, com defasagem na resposta das correntes da ordem do período inercial local (31 h). Também foram obtidos máximos significativos de correlação entre as correntes de fundo normais à isóbata, e a componente paralela do vento, concordantes com mecanismos de intrusões de Água Central do Atlântico Sul (ACAS) na plataforma continental, as quais antecedem a conhecida ressurgência costeira de CF. Sazonalmente, os resultados concordaram principalmente com as variações de posicionamento da frente da CB na QPC e, secundariamente, com a variabilidade dos ventos. Os dados de temperatura indicaram presença quase permanente da ACAS no fundo, e os máximos de correlação obtidos com as correntes paralelas à isóbata indicam que águas mais quentes, oriundas do núcleo da CB (Água Tropical), se aproximam do fundo da QPC, principalmente durante o verão. As correntes de maré se mostraram fracas em todo o período avaliado, com importância decrescendo da superfície para o fundo (20 e 10% da variância, respectivamente) / Current data throughout the water column and temperatures at the bottom from about three years have been analyzed in order to evaluate the hydrodynamic and thermal behavior near the Cabo Frio (CF) continental shelf break (23° 20\'S - Rio de Janeiro, Brazil). The Brazil Current (BC) forces movements pointing to SW, isobath-aligned, on all vertical levels. The speed varies seasonally, with surface mean currents maximum on summer (58.7 cm/s) and spring (41.4 cm/s), and minimum on winter (31.0 cm/s) and autumn (22.8 cm/s). Significant maximum correlation was found between subinertial winds and driven-wind currents, both isobath-aligned, with a delay next to the local inertial period (31 hours). Significant maximum correlation were also obtained between bottom cross-isobath currents and the isobath-aligned component of the wind, consistent with the South Atlantic Central Water (SACW) transport towards the continental shelf, which antedates the well-known coastal CF upwelling. Seasonally, the results agreed mainly with the positioning variations of the BC to the shelf break and, secondly, with the local winds variability. The temperature values below the 18ºC (SACW thermohaline index) was almost permanent on the bottom of the shelf break, and the maximum correlation obtained with current along the isobath indicates that the warmer water of the BC nucleus (Tropical Water) approaches to the bottom of the shelf break, especially during the summer. Tidal currents were weak during the entire sampling period, decreasing the relative strength from the surface to the bottom (20% and 10% of the variance, respectively)
445

Distribuição espacial e temporal de proteínas e ácidos húmicos em lagoa rasa subtropical

Centuriao, Tiago Carrard January 2016 (has links)
O presente trabalho avaliou a variabilidade espacial e temporal de ácidos húmicos (HA) e proteínas (PROT), em uma grande lagoa rasa subtropical. Para tanto, foi usado Cromatógrafo Líquido de Alta Eficiência por Exclusão de Tamanho (HPLC-SEC). Foram incluídas como variáveis explanatórias, carbono orgânico dissolvido (COD), nitrogênio total (NT), nitrogênio total dissolvido (NTD), cor, pH e temperatura. A área de estudo foi a Lagoa Mangueira, uma grande lagoa rasa oligo-mesotrófica inserida ao Sistema Hidrológico do Taim – SHT. As amostras foram coletadas em quatro campanhas, durante o ano de 2010, em dezenove pontos diferentes, compreendendo as zonas litorâneas e pelágica, localizadas no sul, centro e norte da lagoa. Resultados indicaram que a Lagoa Mangueira apresenta heterogeneidade temporal interanual em relação a estas variáveis, ao mesmo tempo que possui um perfil longitudinal homogêneo, não evidenciando um arranjo espacial definido. / The present work evaluated spatial and temporal variability of humic acids (HA) and proteins (PROT) in a large subtropical shallow lake. For this purpose, High Performance Liquid Chromatograph by Size Exclusion (HPLC-SEC) was used. Dissolved organic carbon (DOC), total nitrogen (TN), total dissolved nitrogen (TDN), color, pH and temperature were included as explanatory variables. The study area was Mangueira lake, a large shallow oligo-mesotrophic lake located into the Taim Hydrological System. The samples were collected in four samplings during the year 2010 at nineteen different points, including the littoral and pelagic zones, located in the south, center and north of the lake. Results showed that the Mangueira lake presents interannual temporal heterogeneity in relation to these variables, at the same time that it has a homogeneous longitudinal profile, not evidencing a defined spatial arrangement.
446

Plan de negocio para la implementación de un Hotel Ecoturístico Flotante en la ciudad de Iquitos

Alvarado Anampa, Max Henrry, Jara Vela, Jorge Danilo, Manrique Véliz, Mitchell Bruce 20 August 2019 (has links)
El presente plan de negocios tiene por objetivo establecer la viabilidad técnica y financiera para desarrollar un proyecto hotelero de categoría tres estrellas en la amazonia de Iquitos. La investigación iniciada con un diagnóstico de la situación del mercado externo general, a través del análisis PESTE; identificó un macroentorno favorable para el desarrollo del presente proyecto; por otro lado; mediante un análisis del entorno competitivo (análisis de las cinco fuerzas de Porter) se logró identificar la intensidad de la competencia local y sus eslabonamientos estrechos existentes con los principales proveedores u operadores turístico-locales. Por tanto; ello ha permitido visualizar un panorama competitivo favorable para incursionar en el sector hotelero de la ciudad de Iquitos con una propuesta de valor ecológica diferenciada. Los resultados obtenidos mediante una investigación de mercado (encuestas de campo) ha conducido a determinar que la principal preferencia de consumo en los servicios hoteleros en la ciudad de Iquitos se basa en hospedajes de categoría tres estrellas; cuyo principal demandante son los trabajadores profesionales tanto dependientes como independientes. Así mismo; mediante un estudio de mercado (investigación del tipo cuantitativa); efectuado al mercado hotelero de Iquitos; se ha logrado identificar y cuantificar la demanda pernoctaciones insatisfecha en la categoría tres estrellas en la ciudad de Iquitos; corroborando las oportunidades de negocio en este sector. El estudio económico-financiero efectuado a la presente propuesta ecológica de negocio concluyó la viabilidad técnica y financiera del proyecto. Los resultados de este estudio determinaron que los flujos; tanto económico como financiero descontados al costo ponderado de capital y a la tasa mínima requerida por el accionista respectivamente; son positivos. Lo que implica que los beneficios futuros privados derivados de las operaciones comerciales del hotel ecológico son superiores a los costos o egresos incurridos. Por lo que resulta rentable para el inversionista desarrollar este tipo de iniciativa privada. En ese contexto, la originalidad del presente proyecto radica en la construcción de un hotel ecológico flotante; cuya oferta de servicios plantea una propuesta de valor que armoniza el diseño físico y las operaciones comerciales del hotel con la biodiversidad natural y cultural de la amazonia de Iquitos. Por ello la ubicación del hotel situada a 16 Km al Noreste de la ciudad de Iquitos; entre las intersecciones del rio Nanay y el lago Mapacocha; contribuye a desarrollar una propuesta ecológica de negocio no solo basándose en servicios únicos de hospedaje sino en la prestación de múltiples servicios complementarios de entretenimiento. / The purpose of this business plan is to establish the technical and financial viability to develop a three-star hotel project in the Amazonia of Iquitos. The research started with a diagnosis of the situation of the general external market, through the PESTE analysis, identified a favourable macro environment for the development of the present project, on the other hand, by means of an analysis of the competitive environment (analysis of the five forces of Porter ) it was possible to identify the intensity of local competition and its existing close links with the main providers or touristic-local operators. Therefore, this has allowed us to visualize a favourable competitive landscape to enter the hotel sector of the city of Iquitos with a proposal of differentiated ecological value. The results obtained through market research (field surveys) has led to determine that the main preference of consumption in hotel services in the city of Iquitos is based on three-star category accommodations, whose main claimant is professional workers, both dependent and independent. Likewise, through a market study (research of quantitative type), carried out in the hotel market of Iquitos, it has been possible to identify and quantify the demand for unsatisfied overnight stays in the category three stars in the city of Iquitos, corroborating the business opportunities in this sector. The economic-financial study carried out on the present ecological business proposal concluded the technical and financial feasibility of the project. The results of this study determined that the flows, both economic and financial discounted at the weighted cost of capital and at the minimum rate required by the shareholder respectively, are positive. This implies that the private future benefits derived from the commercial operations of the ecological hotel are higher than the costs or expenses incurred. So, it is profitable for the investor to develop this type of private initiative. In this context, the originality of this project lies in the construction of a floating eco-friendly hotel; whose offer of services proposes a value proposition that harmonizes the physical design and its commercial operations of the hotel with the natural and cultural biodiversity of the Amazon of Iquitos. Therefore the location of the hotel located 16 Km northeast of the city of Iquitos; between the intersections of the Nanay River and Lake Mapacocha; it helps to develop an ecological business proposal not only based on unique hosting services but on the provision of multiple complementary entertainment services. / Trabajo de investigación
447

Phytoplankton Ecology of Lake Kivu (Eastern Africa)/ Écologie du phytoplancton du lac Kivu (Afrique de l'Est)

Sarmento, Hugo 29 September 2006 (has links)
With a volcanic origin, Lake Kivu is deep and meromictic, and shows a very particular limnology and some astonishing features. The data available on its limnology and phytoplanktic communities are limited, dispersed or outdated. This is the first deep, long term study (2002-2004) on limnology and phytoplankton ecology of Lake Kivu, combining different techniques: HPLC analysis of marker pigments, flow cytometry, light, epifluorescence and electron microscopy. Lake Kivu combines a relatively shallow euphotic layer (~18m) usually smaller than its mixed layer (20 – 60 m), and with a weak thermal gradient in the mixolimnion. With an annual average chlorophyll a in the mixed layer of 2.2 mg m-3 and low nutrient levels in the euphotic zone, the lake is clearly oligotrophic. Concerning its phytoplanktonic composition, the most common species were the pennate diatoms Nitzschia bacata Hust. and Fragilaria danica (Kütz.) Lange Bert., and the cyanobacteria Planktolyngbya limnetica (Lemm.) Komárková-Legnerová and Cronberg and Synechococcus sp. Diatoms were the dominant group in the lake, particularly during the dry season episodes of deep mixing. During the rainy season, the stratified water column, with high light and lower nutrient availability, favoured dominance of cyanobacteria. Phycoerythrin-rich phototrophic picoplankton and heterotrophic bacteria cell numbers were constantly high, with relatively subtle spatial, seasonal and vertical variations. In open lake waters, where allochthonous carbon inputs are most probably inconsequential, HNA heterotrophic bacteria abundance is strongly correlated with chlorophyll a. Recent investigations revealed an increasing methane production in the deep waters during the past three decades, leading to an accumulation of gas and the subsequent lowering of the energy required to trigger a devastating release of gasses. The role of primary producers and the probable changes on the export ratio of the organic matter into deep waters after the introduction of the planktivorous sardine from Lake Tanganyika Limnothrissa miodon, is discussed. The actual primary production, 0.71 g C m-2 d-1 (~ 260 g C m-2 y-1), doesn’t seem substantially different from some punctual measurements made in the past, which discards the hypothesis of anthropogenic eutrophication. We believe that the export ratio of organic matter into the deep waters was largely affected by biological changes that could explain part of the methane increase in the past 30 years in Lake Kivu.
448

Essays on nonlinear time series analysis and health economics

Ovanfors, Anna January 2006 (has links)
Diss. Stockholm : Handelshögskolan, 2006 S. 1-125 : 4 uppsatser
449

National Beef Quality Audit - 2011: Survey of Instrument Grading Assessments of Beef Carcass Characteristics

Gray, Gatlan 1989- 14 March 2013 (has links)
The instrument grading assessments for the NBQA-2011 evaluated seasonal trends of beef carcass quality and yield attributes over the course of the year. One week of instrument grading data—HCW, gender, USDA QG, and YG factors—were collected every other month (n = 2,427,074 carcasses) over a 13-month period (November 2010 through November 2011) from four beef processing corporations, encompassing 17 federally inspected beef processing facilities, to create an overview of carcass quality and yield attributes and trends from carcasses representing approximately 8.5% of the U.S. fed steer and heifer population. Mean yield traits were: YG (2.86), HCW (371.3 kg), FT (1.19 cm.), and LM area (88.39 cm^2). The YG distribution was YG 1 (15.7%), YG 2 (41.0%), YG 3 (33.8%), YG 4 (8.5%), and YG 5 (0.9%). Distribution of HCW was <272.2 kg (1.6%), 272.2 kg to 453.6 kg (95.1%), ≥453.6 kg (3.3%). Monthly HCW means were: November 2010 (381.3 kg), January 2011 (375.9 kg), March 2011 (366.2 kg), May 2011 (357.9 kg), July 2011 (372.54 kg), September 2011 (376.1 kg), and November 2011 (373.5 kg). The mean FT for each month was November 2010 (1.30 cm), January 2011 (1.22 cm), March 2011 (1.17 cm), May 2011 (1.12 cm), July 2011 (1.19 cm), September 2011 (1.22 cm), and November 2011 (1.22 cm). The mean marbling score was Small49. USDA QG distribution was Prime (2.7%), Top Choice (22.9%), Commodity Choice (38.6%), and Select (31.5%). Interestingly, from November to May, seasonal decreases (P < 0.001) in HCW and FT were accompanied by increases (P < 0.001) in marbling. These data present the opportunity to further investigate the entire array of factors that determine the value of beef. Datasets utilizing the online collection of electronic data will likely be more commonly used when evaluating the U.S. fed steer and heifer population in future studies. These data indicate the wide array of carcasses produced by the beef cattle industry, and how the frequency of both YG and QG traits change from month-to-month.
450

Decentralised fish seed networks in Northwest Bangladesh : impacts on rural livelihoods

Haque, Mohammad Mahfujul January 2007 (has links)
Ricefield based fish seed production (RBFSP) in irrigated spring (boro) ricefields after initial introductions by external promoters has spread among farmers in parts of Northwest Bangladesh. This approach to producing juvenile fish, rather than by specialised geographically clustered hatchery and nursery enterprises, has been recognised as a strategy for decentralised production that makes large high quality seed available locally and supports food fish production. RBFSP has been promoted by the international NGO CARE as part of a process to improve rice-based livelihoods of farming households using a farmer field school (FFS) approach in two consecutive projects between 1993 and 2005. The approach is technically simple and is based on the stocking of common carp (Cyprinus carpio) eggs and Nile tilapia (Oreochromis niloticus) broodfish in ricefields. As a new approach to farmer level fish seed production, its livelihood impacts on the farming households as well as associated actors; its adoption, adaptation and rejection process in farming households; and its cost-effectives for dissemination at farmer level were not well understood. This thesis mainly applies the concept of the sustainable livelihood approach (SLA) using tools and processes of the growing family of participatory research. A systems approach was used to ensure that the key stakeholders including households, community and extension organizations were included. The study was initiated with a well-being analysis of community households to identify poorer households before exploring impacts of RBFSP on poorer producing households (RF) compared to non-producing (NRF) households based on one-off and longitudinal surveys. Livelihoods impacts on other actors linked directly and indirectly with RBFSP were also investigated. The adoption process of RBFSP at the household level and the cost-effectiveness of its promotion were assessed. Impact studies at the household level showed that RF households were significantly larger and had lower levels of formal education than NRF. Adoption of RBFSP had improved practical skills and hence substantially improved human capital in RF households. RF households tended to have more of their ricefish plots located adjacent to their households. Poor and intermediate adopters had smaller riceplots than better-off households but higher seed production efficiencies (poor-315.1 kg fingerlings/ha; intermediate-419.1 kg fingerlings/ha) than better-off households (294.6 kg fingerlings/ha). In addition to direct consumption of large fingerlings, RF households restocked them for further growth in their household ponds in doing so increasing yields by 60%. Fish consumption increased substantially in RF households based on their own production reducing their dependency on purchase from markets. The year round longitudinal survey revealed that activities for RBFSP were compatible with their existing rice-based agriculture activities for household members including men, women and children. The relatively limited income from fingerling production improved cash flow in the low income months. Consumption of large size fingerlings from ricefields provided nutrient dense food in the ‘hungry gap’ months when supplies of wild fish were poor, smoothing consumption. Apart from RF households, RBFSP extended its livelihoods impacts to a wide range of actors in and around the seed producing community. Poor fry traders were found to be key actors in the spread and support of RBFSP. On average fry traders supplied fingerlings to 35 foodfish producers within a mean distance of 5 Km from producing households in a community where RBFSP was well established. The end users (foodfish producers) included households with their own ponds, ponds with multiple ownership and larger waterbodies leased by small groups. Locally available RFBSP juveniles were attractive to each of these groups, supplementing hatchery derived seed. A large number of complex socio-cultural and technical factors were related to household level adoption of RBFSP. The major factors included use of cash generated to prevent distress sales of rice; lack of requirement to use pesticide in ricefields; meeting the household consumption demand; capacity to restock fingerlings in ponds; lack of any negative effects on rice production; increased non-stocked fish production in riceplots; simplicity of the technology; ease of fish harvest from riceplots; increased ability to gift fingerlings/foodfish to relatives and neighbours; more efficient use of both riceplot and irrigation pumps. The most important reasons for households not attempting or quickly rejecting RBFSP were labour conflicts with other activities. However, lost access to the riceplots through changes in tenure was the most common cause of late rejection by households who had practiced RBFSP for several years after withdrawal of CARE support. Location of fish seed producing plots close to the homesteads facilitated household women to contribute to seed production activities through feeding and looking after fish. Women were able to decide and control resources generated from fingerling sales as well as choosing to gift fingerlings to their relatives. Informal transfer of fingerlings in this way stimulated spread of RBFSP. Decentralised fish seed production was promoted through FFS very cost effectively. The introduction of an improved strain of Nile tilapia (GIFT) broodfish greatly enhanced the returns from decentralised seed production based on common carp alone. High levels of secondary adoption improved benefits from promoting RBFSP. The major benefit derived from the improved returns to food fish farmers using locally produced seed. Higher levels of net present value (NPV) and benefit cost ratio (BCR) were achieved based on promotion of mixed-sex tilapia in RBFSP than mono-sex tilapia produced in a large scale central hatchery. Cost-effectiveness in terms of multiplier development impacts on ramification of secondary adopters and, income of fry traders and foodfish producers, RBFSP also showed better performance than a mono-sex tilapia hatchery.

Page generated in 0.0213 seconds