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  • 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.
1

Invasion-induced Changes to the Offshore Lake Ontario Food Web and the Trophic Consequence for Bloater (Coregonus hoyi) Reestablishment

Stewart, Thomas Joseph 21 April 2010 (has links)
I compared changes in offshore Lake Ontario major species-group biomass, production and diets before (1987-1991) and after (2001-2005) invasion-induced ecological change. I synthesized the observations into carbon-based mass-balanced food webs linking two pathways of energy flow; the grazing chain (phytoplankton-zooplankton-fish) and the microbial loop (autotrophic bacteria-heterotrophic protozoans) and determined how the structure and function of the food web changed between time-periods. I use the food web descriptions to simulate the reestablishment of native deepwater bloater. I developed empirical models describing spatial variation in temperature and applied them to investigate predator temperature distributions, bioenergetic consequences of alewife diet and distribution shifts, and zooplankton productivity. Primary production declined as did the biomass and production of all species-groups except Chinook salmon. Total zooplankton production declined by approximately half with cyclopoid copepod production declining proportionately more. Zooplankton species richness and diversity were unaffected. Alewife adapted to low zooplankton production by consuming more Mysis, increasing their trophic level. The increased prey-size and exploitation of spatial heterogeneity in resource patches and temperature may have allowed alewife to maintain their growth efficiency. The trophic level also increased for smelt, adult sculpin, adult alewife and Chinook salmon. Phytoplankton grazing rates declined and predation pressure increased on Mysis, adult smelt and alewife, and decreased on protozoans. Resource to consumer trophic transfer efficiencies changed; increasing for protozoans, Mysis, Chinook salmon and other salmonines and decreasing for zooplankton, prey-fish and benthos. The changes suggest both bottom-up and top-down influences on food web structure. The direct trophic influences of invasive species on the offshore Lake Ontario food web were minor. Carbon flows to Mysis indicated an important, and changing ecological role for this species and we hypothesize that Mysis may have contributed to Diporeia declines. Simulations suggest that only a small reestablished bloater population, limited by Diporeia production, could be sustained.
2

Invasion-induced Changes to the Offshore Lake Ontario Food Web and the Trophic Consequence for Bloater (Coregonus hoyi) Reestablishment

Stewart, Thomas Joseph 21 April 2010 (has links)
I compared changes in offshore Lake Ontario major species-group biomass, production and diets before (1987-1991) and after (2001-2005) invasion-induced ecological change. I synthesized the observations into carbon-based mass-balanced food webs linking two pathways of energy flow; the grazing chain (phytoplankton-zooplankton-fish) and the microbial loop (autotrophic bacteria-heterotrophic protozoans) and determined how the structure and function of the food web changed between time-periods. I use the food web descriptions to simulate the reestablishment of native deepwater bloater. I developed empirical models describing spatial variation in temperature and applied them to investigate predator temperature distributions, bioenergetic consequences of alewife diet and distribution shifts, and zooplankton productivity. Primary production declined as did the biomass and production of all species-groups except Chinook salmon. Total zooplankton production declined by approximately half with cyclopoid copepod production declining proportionately more. Zooplankton species richness and diversity were unaffected. Alewife adapted to low zooplankton production by consuming more Mysis, increasing their trophic level. The increased prey-size and exploitation of spatial heterogeneity in resource patches and temperature may have allowed alewife to maintain their growth efficiency. The trophic level also increased for smelt, adult sculpin, adult alewife and Chinook salmon. Phytoplankton grazing rates declined and predation pressure increased on Mysis, adult smelt and alewife, and decreased on protozoans. Resource to consumer trophic transfer efficiencies changed; increasing for protozoans, Mysis, Chinook salmon and other salmonines and decreasing for zooplankton, prey-fish and benthos. The changes suggest both bottom-up and top-down influences on food web structure. The direct trophic influences of invasive species on the offshore Lake Ontario food web were minor. Carbon flows to Mysis indicated an important, and changing ecological role for this species and we hypothesize that Mysis may have contributed to Diporeia declines. Simulations suggest that only a small reestablished bloater population, limited by Diporeia production, could be sustained.
3

Abordagem baseada em lógica fuzzy para alocação de indicadores de faltas em sistemas de distribuição de energia elétrica / Approach based on fuzzy logic for fault indicator allocation in power distribution systems

Souza, Débora Maria Barbosa Salvador de 01 October 2009 (has links)
Este trabalho apresenta uma metodologia para alocação eficiente de dispositivos indicadores de faltas em sistemas de distribuição de energia elétrica. São avaliadas como as principais variáveis que influenciam na quantificação da potencialidade para instalação de dispositivos indicadores de faltas se comportam ao longo do tronco principal dos alimentadores de distribuição de energia elétrica. Como metodologia, empregou-se sistemas de inferência fuzzy para quantificar a referida potencialidade a partir das variáveis avaliadas. Resultados com dados reais destacam também a eficiência da metodologia proposta para quantificar e avaliar a rede de dispositivos indicadores já existentes em alimentadores. / This work presents a methodology for efficient allocation of fault indicator devices in electric power distribution systems. The behavior of the main variables that influence in the quantification of the potentiality for installation of fault indicator devices were analyzed taking into account the feeder length. In methodology terms, fuzzy inference systems were used to quantify this potentiality from the analyzed variables. Results with real data have also highlighted the efficiency of the proposed methodology to quantify and to evaluate the fault indicator device network already existent in power distribution feeders.
4

Abordagem baseada em lógica fuzzy para alocação de indicadores de faltas em sistemas de distribuição de energia elétrica / Approach based on fuzzy logic for fault indicator allocation in power distribution systems

Débora Maria Barbosa Salvador de Souza 01 October 2009 (has links)
Este trabalho apresenta uma metodologia para alocação eficiente de dispositivos indicadores de faltas em sistemas de distribuição de energia elétrica. São avaliadas como as principais variáveis que influenciam na quantificação da potencialidade para instalação de dispositivos indicadores de faltas se comportam ao longo do tronco principal dos alimentadores de distribuição de energia elétrica. Como metodologia, empregou-se sistemas de inferência fuzzy para quantificar a referida potencialidade a partir das variáveis avaliadas. Resultados com dados reais destacam também a eficiência da metodologia proposta para quantificar e avaliar a rede de dispositivos indicadores já existentes em alimentadores. / This work presents a methodology for efficient allocation of fault indicator devices in electric power distribution systems. The behavior of the main variables that influence in the quantification of the potentiality for installation of fault indicator devices were analyzed taking into account the feeder length. In methodology terms, fuzzy inference systems were used to quantify this potentiality from the analyzed variables. Results with real data have also highlighted the efficiency of the proposed methodology to quantify and to evaluate the fault indicator device network already existent in power distribution feeders.
5

Nuosavybės teisių į žemę atkūrimas Panevėžio mieste / Reestablishment of Real Property Rights in Panevezys City

Balčas, Linas 03 June 2009 (has links)
Nuosavybės teisių į miesto žemę atkūrimo darbai teisiškai buvo sureglamentuoti tik 2002 m. patikslinus įstatymą. Nuo to laiko piliečiams ne tik suteikiami nuosavybėn žemės sklypai prie pastatų ar nauji žemės sklypai individualiai statybai, bet ir grąžinama natūra laisva (neužstatyta) miesto žemė. Bendras žemės plotas, į kurį prašoma atkurti nuosavybės teises Panevėžio mieste – 2482 ha. Iki 2009 m. pradžios Panevėžio mieste atkurtos nuosavybės teisės į 43,6 proc. pretendentų prašymuose nurodyto ploto. Grąžinta natūra 134 ha žemės. 2009 m. pradžioje dar nebuvo suteikta nuosavybėn žemės sklypai 703 asmenims. Esant tokiems žemės reformos tempams, visus žemės reformos darbus Panevėžio mieste bus galima užbaigti tik per 11 metų. Siekiant šį procesą paspartinti, siūloma: miesto savivaldybei rengti daugiau detaliųjų planų, kuriuose suformuojami kompensavimui skirti žemės sklypai; sudaryti sąlygas už miesto žemę gauti žemės sklypus kaimo vietovėje, – ne tik žemės ūkio paskirties žemėje, bet ir miškų ūkio paskirties žemėje. / Reestablishment of urban real property rights legally were regulated in 2002, when legal act was corrected. From that time, the citizens are not only granted for ownership of land parcels near buildings or new land parcels for individual construction, but restored free natural urban land. General land plot, for which is applied to reestablish property rights in Panevezys city is 2482 ha. Till the beginning of 2009, reestablished property rights to the 43.6 percent from all applied land plot. Restored 134 ha of free natural land. In the beginning of 2009 the property rights were not reestablished to 703 citizens. According to the situation all the land reform in Panevezys will finish after 11 years. The way to solve this problem faster, we suggest municipality, to do more detail plans of creation land parcels for compensation, to create conditions for citizens to get a rural land and forest land in accordance of urban land.

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