• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 46
  • 21
  • 14
  • 9
  • 5
  • 4
  • 3
  • 3
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 128
  • 128
  • 20
  • 18
  • 18
  • 16
  • 16
  • 15
  • 15
  • 15
  • 14
  • 13
  • 12
  • 10
  • 9
  • 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.
41

Energetic Carrying Capacity Of Habitats Used By Spring-Migrating Waterfowl In The Upper Mississippi River And Great Lakes Region

Straub, Jacob 29 September 2008 (has links)
No description available.
42

Demographic Consequences Of Managing For Florida Scrub-jays (aphelocoma Coerulescens) On An Isolated Preserve.

Lyon, Casey 01 January 2007 (has links)
Many species naturally occupy discrete habitat patches within a mosaic of habitats that vary in quality. The Florida scrub-jay (Aphelocoma coerulescens) is endemic to Florida scrub, a habitat that is naturally patchy and greatly reduced in area over recent decades owing to development and urbanization. Because of this habitat loss, future management of Florida scrub-jays will focus on smaller, fragmented tracts of land. My study examines such a tract, Lyonia Preserve, southwest Volusia County, FL. This preserve was unoccupied by scrub-jays prior to habitat restoration. The preserve is now frequently managed exclusively for scrub-jays as a habitat island surrounded by development. Management of the preserve includes roller chopping, root raking, timbering, and "oak stripping" where islands of oak patches are left intact while the rest of the area is roller chopped. I investigate what, if any, demographic consequences may be associated with the habitat management and the spatial setting of the preserve. I used population data collected in this area since 1992 to examine population growth and responses to habitat restoration within the preserve and habitat destruction outside the preserve. I mapped territories and measured survival and recruitment of scrub-jays, and dispersal into and out of the study area, for two and a half years. Since restoration, the population has shown logistic growth, with the area supporting higher than average densities of scrub-jay family groups. Observed density of the population and territory size varied between study years. Breeder survival values were positively related to territory size and significantly lower during periods of highest observed density. However, recruitment (yearling production) showed no relationship to territory size. Dispersal to isolated habitat patches was observed; likewise, several failed dispersal events were noted. No immigration into the study area was observed; however these data may be underrepresented since not all scrub-jays in and outside of the preserve were banded, and data collection was limited during the initial colonization period. High densities inside the preserve may therefore be both a result of frequent habitat management in the form of mechanical treatment as well as crowding of individuals due to outside habitat destruction. The results indicate that carrying capacity of habitat for scrub-jays may be raised by frequent, mechanical management; however, if the area is isolated, management may result in high densities and negative demographic consequences, e.g., reduced breeder survival. Negative effects of management may be avoided by subjecting smaller areas to mechanical treatment with increased time between treatments. Land managed for Florida scrub-jays should be contiguous or connected with other scrub habitats so that surplus birds from the managed areas have a refuge and do not contribute to increased densities. Regulatory officials should use caution when allowing for "take" of scrub-jay habitat as the effects may extend beyond the local habitat being destroyed.
43

Exploring the Structure and Development of Management Prescriptions for Public Lands

Cahill, Kerri Lynn 18 November 2003 (has links)
Management prescriptions that describe desired conditions for resources and visitor experiences have become widely accepted as an important component of public land management plans. However, very little effort is spent on evaluating and learning about this part of the planning process. This research identifies and addresses the need to explore opportunities for additional guidance on the development of management prescriptions, by (1) evaluating the current perception of the purpose of management prescriptions; (2) developing criteria and other tools to guide the development of management prescriptions based on the experiences of public land management professionals; and (3) testing an alternative method for collecting visitor preference data regarding social, resource and management conditions to inform development of management prescriptions. The first two papers report the results of a visitor preference study, using the stated choice method, conducted in Acadia National Park. The purpose of the first paper is to identify visitor preferences for tradeoffs among social, resource and related management conditions of the recreation setting. The purpose of the second paper is to identify differences among visitor preferences for social, resource and management conditions in various recreation settings. By considering the integrative nature of these attributes and the relative importance to visitors across recreation settings, the definition of management prescriptions can be better informed. To further investigate the results of the stated choice method and ensure the validity of the data, a verbal protocol assessment was applied to a sample of the stated choice survey respondents. The purpose of the third paper is to reexamine the role of management prescriptions for park management planning and investigate tools for facilitating development of management prescriptions. The study included in-depth interviews, participant observation of a three-day planning workshop and a written survey. All of the participants in the various components of the study were National Park Service land management professionals. The study resulted in a list of the purpose and criteria for management prescriptions and a related menu of desired condition topics, which will be integrated into planning guidance to aid the development of unique and effective management prescriptions for national parks. / Ph. D.
44

Finite element modeling of twin steel box-girder bridges for redundancy evaluation

Kim, Janghwan 08 October 2010 (has links)
Bridge redundancy can be described as the capacity that a bridge has to continue carrying loads after suffering the failure of one or more main structural components without undergoing significant deformations. In the current AASHTO LRFD Bridge Design Specification, two-girder bridges are classified as fracture critical, which implies that these bridges are not inherently redundant. Therefore, two-girder bridges require more frequent and detailed inspections than other types of bridges, resulting in greater costs for their operation. Despite the fracture-critical classification of two-girder bridges, several historical events involving the failure of main load-carrying members in two-girder bridges constructed of steel plate girders have demonstrated their ability to have significant reserve load carrying capacity. Relative to the steel plate girder bridges, steel box-girder bridges have higher torsional stiffness and more structural elements that might contribute to load redistribution in the event of a fracture of one or more bridge main members. These observations initiated questions on the inherent redundancy that twin box-girder bridges might possess. Given the high costs associated with the maintenance and the inspection of these bridges, there is interest in accurately characterizing the redundancy of bridge systems. In this study, twin steel box-girder bridges, which have become popular in recent years due to their aesthetics and high torsional resistance, were investigated to characterize and to define redundancy sources that could exist in this type of bridge. For this purpose, detailed finite element bridge models were developed with various modeling techniques to capture critical aspects of response of bridges suffering severe levels of damage. The finite element models included inelastic material behavior and nonlinear geometry, and they also accounted for the complex interaction of the shear studs with the concrete deck under progressing levels of damage. In conjunction with the computational analysis approach, three full-scale bridge fracture tests were carried out during this research project, and data collected from these tests were utilized to validate the results obtained from the finite element models. / text
45

FROTH FLOTATION PERFORMANCE ENHANCEMENT BY FEED CAVITATION AND MAGNETIC PLASTIC PARTICLE ADDITION

Saracoglu, Mehmet 01 January 2013 (has links)
Froth flotation is the most commonly used process to recover and upgrade the portion of the coal preparation plant feed that has a particle size smaller than 150 microns. Problems that occur when employing froth flotation in the coal industry include i) coal surfaces that are weakly-to-moderately hydrophobic, and ii) flotation systems that are overloaded and limited by insufficient retention time. Research was performed to evaluate techniques that could be implemented to improve flotation performance under the aforementioned scenarios. Pre-aeration of flotation feed using a cavitation system was extensively evaluated in laboratory and full-scale test programs. The benefits of adding hydrophobic, magnetic plastic particles were also investigated to improve froth stability and increase bubble surface area. Laboratory tests revealed that pre-aeration through a cavitation tube improved coal recovery by as much as 20 absolute percentage points in both conventional cells and flotation columns when treating difficult-to-float coals. Carrying capacity increased by 32% which was projected to provide a 4 t/h increase in flotation recovery for a typical 4-m diameter flotation column. Product size analyses suggest that the improved particle recovery was more pronounced for the finest coal fractions as a result of particle agglomeration, resulting from the use of the nucleated air bubbles on the coal surfaces as a bridging medium. In-plant testing of a commercial-scale cavitation system found that feed pre-aeration could reduce collector dosage by 50% when no additional air is added and by 67% when a small amount of air is added to the feed to the cavitation system. At a constant collector dosage, recovery increased by 10 absolute percentage points with cavitation without additional air and 17 absolute points when additional air is provided. The addition of hydrophobic plastic particles to the flotation feed at a 10% concentration by weight was found to substantially improve froth stability thereby elevating the recovery and enhancing carrying-capacity. Test results showed that the primary flotation improvements were directly linked to the coarsest particle size fractions in the plastic material which supports the froth stability hypothesis. Combustible recovery was increased up to 10 percentage points while producing the desired concentrate quality.
46

Percepce turistických destinací Špindlerův Mlýn a Rokytnice nad Jizerou rezidenty / Percepcion tourist destinations Špindlerův Mlýn and Rokytnice nad Jizerou by residents

Svobodová, Nikola January 2014 (has links)
The purpose of my thesis is the application of the concept of the socio-cultural-carrying capacity of the territory via example of giant tourist destinations Špindlerův Mlýn and Rokytnice nad Jizerou. For these two destinations basic information about locations are discussed in more detail; as a major ski resort, including equipment material and technical bases, and local infrastructure. In the theoretical part, I focus on definitions and explanations of concepts of tolerable capacity of the area, with a focus on socio-cultural carrying capacity. Furthermore, I discuss Doxey's irritant index which describes the relationship between residents and tourists. In the practical part I focus on the perception of tourism with these specific destinations residents. On the basis of results of my investigation to be carried out probable form of questionnaires and direct interviews, I assess the level of socio-cultural carrying capacity. Then conduct a comparison of the results obtained in Špindlerův Mlýn and Rokytnice nad Jizerou. The conclusion gives recomendation and a little reflection with satisfaction of the residents lifestyle in these communities and further development of these destinations from the perspective of residents.
47

Populationsutveckling och bärkraft för lodjur (Lynx lynx) i Östergötland / Population trends and carrying capacity for eurasian lynx (Lynx lynx) in Östergötland

Barrefelt, Linnea January 2019 (has links)
Jordens biologiska mångfald minskar i en allt snabbare takt, men mitt i denna ekologiska katastrof börjar arter på vissa håll att återkomma. De stora rovdjuren i Europa är ett sådant exempel. Från att ha varit försvunna från stora delar av sina utbredningsområden är de flesta populationer numera stabila eller ökande. I Skandinavien har lodjurspopulationen expanderat och efter närmare 100 års reproduktiv frånvaro förekommer åter föryngringar i Sydsverige. I Östergötland finns i dagsläget ca 50–55 individer och mycket tyder på att stammen kommer att fortsätta öka. Genom att sammanställa och analysera data från inventeringsrapporter, observationsloggar och avskjutningsstatistik har jag undersökt lodjurspopulationens utveckling i Östergötland och beräknat länets bärkraft för lo. Beräkningen av bärkraften har utgått från klövviltförekomsten samt mängden lämpligt habitat. Resultaten visar att Östergötland har gott om lämpligt habitat och en hög bytesdensitet, som är jämförbar med flera lodjurstäta områden i Europa. Givet dessa förutsättningar har Östergötland en bärkraft för lo som ligger långt över dagens populationsnivå. Uppskattningsvis kan Östergötland hålla mellan 80–140 självständiga individer. Detta skulle innebära en fördubbling av dagens antal och kunna leda till såväl positiva som negativa konsekvenser för samhället. Lodjur kan innebära ett hot mot tamboskap, men de senaste årens rapportering visar att angreppen orsakade av lodjur är begränsade. Även påverkan på klövviltstammarna är i dagsläget försumbar. På sikt skulle dock en större lodjurspopulation kunna reglera klövviltet och på så vis minska mängden trafikolyckor och skador på skog. / Global biological diversity is declining at rates comparable to historic mass extinction events. Despite this, some species are returning to their former ranges, an example being the great carnivores in Europe. After being driven to the verge of extinction, most of today’s populations have recovered to a stable level. The Eurasian lynx (Lynx lynx) has re-expanded its range in Scandinavia and, after almost 100 years, is once again reproducing in southern Sweden. There are currently about 50-55 individuals in Östergötland county, and many factors implies that their number will continue to grow. By collecting and analysing data from different governmental reports and other sources I have tried to cover the development of Östergötland’s lynx population and to calculate the carrying capacity. The calculations are based on ungulate densities and amount of suitable habitat. The results of the study show that Östergötland contains a large amount of connected woodland habitat and high densities of prey, comparable to regions in Europe with high occurrence of lynx. Given these circumstances Östergötland has the capacity to support approximately 80-140 independent individuals. These numbers are twice as large as today’s population level and if reached could lead to positive as well as negative consequences for society. The lynx is a known threat to livestock but reports from recent years suggests that lynx attacks on sheep in Östergötland are limited. The effects of the current lynx population on ungulate demographics are also negligible. Although, these effects might increase with a larger lynx population, leading to lower rates of vehicle collisions and less damage in the forestry sector.
48

Estudo de alternativas locacionais para a viabilidade ambiental de empreendimentos: o caso do aeroporto de Ribeirão Preto - SP / The study of locational alternatives for environmental viability: the case of the airport of Ribeirão Preto - SP

Furlanetto, Tiago 03 September 2012 (has links)
Contexto - O estudo de alternativas de localização é uma etapa importante do processo de avaliação de impacto ambiental, tratado por muitos como o \"coração\" do processo e através do qual o empreendedor busca responder aos interessados sobre a viabilidade ambiental de seu empreendimento. Porém, apesar da conhecida importância, existem deficiências nos estudos ambientais com relação à consideração e à discussão de alternativas locacionais de atividades, principalmente em relação àquelas potencialmente causadoras de significativos impactos ambientais, como são os aeroportos. Responsáveis por relevantes impactos ambientais nos centros urbanos, os aeroportos geralmente estão envolvidos em conflitos referentes ao uso e ocupação do solo, representando um dos maiores agentes de degradação ambiental e social, necessitando, portanto, de um eficiente estudo locacional que contemple parâmetros sociais, ambientais, além dos técnicos e econômicos. Objetivo - Assim, o objetivo do presente trabalho é avaliar como as alternativas de localização de atividades, com foco em aeroportos, são contempladas nos estudos de impacto ambiental. Metodologia Para se atingir esse objetivo, aplicou-se uma metodologia de base qualitativa, descritiva e exploratória, que apresenta como etapas: revisão bibliográfica, levantamento de critérios utilizados para definição da localização de aeroportos em âmbito nacional e internacional, organização e avaliação dos critérios levantados e, por fim, aplicação desses critérios no caso do aeroporto de Ribeirão Preto, SP. Resultados - Ficou em destaque a necessidade da prévia análise do território, baseada nos possíveis impactos da atividade e nas aptidões e restrições do meio, a fim de se analisar a viabilidade ambiental do empreendimento, evitando-se, desse modo, futuros conflitos de ordem social e ambiental. Especificamente para o caso estudado, os resultados mostram que houve falhas na metodologia de análise das alternativas locacionais utilizadas no EIA, sobretudo em relação à escolha dos critérios e omissão de informações relevantes para a tomada de decisão. Também, o presente trabalho conclui pela existência de sítios aptos e indicados para a localização de aeroportos em Ribeirão Preto, SP e a inviabilidade do sitio apontado pelo EIA como a melhor opção. / Context - The study of alternative localizations is an important step in the process of environmental impact assessment, treated by many as the \"heart\" of the process and through which the entrepreneur seeks to answer to stakeholders the environmental viability of their enterprise. However, although this known importance, there are shortcomings in environmental studies in relation to consideration and discussion of alternative locational activities, establishing a contradiction and a gap in which the present study staff. Objective - The objective of this study is to evaluate how the alternative locations of activities are contemplated in environmental impact statement. Methodology - To achieve this goal was applied a methodology based on qualitative, descriptive and exploratory character, which presents the following steps: a literature review, survey of criteria used to define the location of airports nationally and internationally, organization and evaluation the data collected and, finally, application of these criteria in the case of airport Ribeirão Preto, SP. Results - It was highlighted the need for preliminary analysis of the territory, based on the potential impacts of activities and capabilities and constraints of the environment, in order to analyze the environmental feasibility of the project, avoiding thus future conflicts social and environmental . Specifically for the case study, the results show that there were flaws in the methodology used locational analysis of alternatives in EIA, especially in relation to the choice of criteria and omission of relevant information for decision making. Also, this study indicates the existence of other suitable sites and more pointed than that indicated by EIA as the best option.
49

Estimativa da população de cães errantes e a sua associação com fatores socieconômicos e ambientais / Estimation of stray dog\'s population and its association with socioeconomics and environmental factors

Guilloux, Aline Gil Alves 03 November 2011 (has links)
A população de cães errantes tem sido um problema na sociedade moderna e levanta discussão sobre o bem estar dos animais, a responsabilidade ambiental e assuntos relacionados saúde pública, como agressão, zoonoses e acidentes de trânsito. São Paulo é uma cidade com mais de dez milhões de habitantes e uma população de cães domiciliados em torno de 2,5 milhões de animais. Não há pesquisas a respeito da distribuição da população de cães errantes e isso dificulta o planejamento de ações de intervenção neste campo. O problema foi abordado do ponto de vista da probabilidade de abandono e capacidade de suporte ambiental. Foi criado um escore composto por treze variáveis de risco de abandono. Os dados foram agrupados por distrito administrativo e estes classificados em três categorias (tercis). Foi definida uma amostra de conveniência de seis áreas a serem visitadas, duas em cada categoria, que fossem pequenas e isoladas, passiveis de percorrer a pé. O número de animais foi estimado pelo método de pseudo-captura, utilizando fotos e anotações para identificar os animais. Simultaneamente, foi aplicado um questionário em uma amostra aleatória sistemática dos domicílios de cada área. Das seis áreas visitadas, em duas foi observada presença de cães errantes e em apenas uma delas, uma população fixa. Dos fatores associados a presença de cães errantes, destacam-se os relacionados a proximidade homem-cão e ao ambiente. Intervenções nestes fatores e incentivo à guarda responsável podem ser soluções desejáveis para redução gradativa da população de cães errantes / The stray dog\'s population of has been a problem in modern society and raises discussion on different issues like animal welfare, environmental responsibility and public health matters such as dogs bites, zoonosis and traffic accidents. Sao Paulo is a city with over ten million inhabitants and a population of owned dogs around 2.5 million animals. There are no surveys on the distribution of the population of stray dogs and this hampers any plan of intervention. The problem was accessed from the standpoint of relinquishment probability and environmental carrying capacity. A score was created with thirteen variables, of known risk factors of relinquishment. The data was grouped by district and classified in to three categories (terciles). a convenience sample of six areas was defined, two in each category, which were small and isolated, liable to go through on foot. The number of animals was estimated by the pseudo capture method, using photos and notes to identify the animals. Simultaneously, a questionnaire was administered in a systematic random sample of households in each area. Of the six areas visited, in only two it the presence of stray dogs was observed and only one showing a fixed stray population. Of the factors associated to the presence of stray dogs, one can distinguish: degree of human-dog proximity and those related to environment. Intervention on these factors and encouraging responsible ownership could be a solution to gradually reduce the population of stray dogs.
50

Hållbart Hemsedal : En hållbar turismutveckling för att vara Skandinaviens mest attraktiva resmål?

Kenwood, Catahrina, Nordström, Therese January 2008 (has links)
<p>Sammanfattning</p><p>Hemsedal är en turistdestination mellan Bergen och Oslo, Norge. Deras vision är att vara Skandinaviens mest attraktiva resmål för fjällsport och unika kulturupplevelser. Att söka skapa en hållbar turismutveckling, genom en enhetlig definition av begreppet samt genom lämpliga verktyg, anser författarna är av betydelse för Hemsedal. Detta för att vara konkurrenskraftiga nog till att göra anspråk på titeln Skandinaviens mest attraktiva resmål, samt för en fortlevnad av destinationen. Hemsedal bör vara ekonomisk, ekologisk samt sociokulturellt långsiktigt hållbar. Det är viktigt med en gemensam definition av begreppet hållbar turismutveckling för att bidra till gemensamma mål och ett gemensamt arbete för att skapa en hållbar turismutveckling på destinationen. Syftet med studien är att analysera om det i Hemsedal finns en definition för hållbar turismutveckling. Författarna ämnar undersöka om, och i så fall hur, utvalda aktörer på destinationen arbetar för en sådan utveckling ur ett lokalt perspektiv. Det för att skapa förståelse för destinationsutvecklingen i Hemsedal med fokus på hållbar turismutveckling. Studien är en fallstudie av kvalitativ karaktär och innefattar semistrukturerade intervjuer vilka utfördes på plats i Hemsedal. Även litteratur, rapporter och artiklar studerades. Teorin behandlar hållbar turismutveckling och tar sin utgångspunkt i ekonomisk, ekologisk och sociokulturell hållbarhet. Vidare behandlas strategier för hur aktörer kan arbeta för att skapa en hållbar turismutveckling. Resultatet av studien visar att en medvetenhet om turismutvecklingen och dess effekter på destinationen finns bland de intervjuade aktörerna i Hemsedal. De arbetar för att skapa en hållbar turismutveckling men arbetssätten skiljer sig åt mellan aktörerna och en gemensam definition av begreppet hållbar turismutveckling finns inte.</p><p>Författarna hoppas att med studien väcka intresse samt skänka inspiration till destinationer i allmänhet, men Hemsedal i synnerhet, i deras arbete att skapa en hållbar turismutveckling.</p>

Page generated in 0.1037 seconds