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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.
31

An Investigation of the ca. 2.7 Ga Late Archean Magmatic Event (LAME) in the Superior Province using 1-D Thermal Modelling

Ahmad, Seema 03 March 2010 (has links)
The Late Archean Magmatic Event (LAME), ca. 2.7 Ga, was the greatest crustal addition event in Earth history. My focus is the Superior Province of Canada, where LAME occurred ca. 2.75 – 2.65 Ga. Mantle plumes impinged on the Abitibi subprovince, where ~ 16 km regional thickness of tonalite-trondhjemite-granodiorite (TTG) melt was produced. Granites (sensu stricto) were the last magmatic phase of LAME, with a Superior-wide regional thickness of ~ 1 – 3 km. Assuming a crustal source for both TTG and granites, I use 1-D thermal models to investigate the origin of TTG in the Abitibi subprovince and that of late granites in the Superior Province. Melting curves appropriate to the source of TTG and granites are used to determine the thickness of melt produced in the models. I show that the incorporation of upward melt transfer into a standard model of lower crustal melting may increase the amount of predicted melt by ~ 1/(1-f), where f denotes the fraction of melt that is on average being extracted from the source rocks. Partitioning of heat producing elements between melt and restite reduces the amount of melt produced, but the effect is secondary compared to the increase in melt production through upward melt transfer. For the Abitibi subprovince, I show that the emplacement of a single plume coupled with the emplacement of a 12-km-thick greenstone cover can generate a maximum of ~ 9-km-thickness of TTG melt. However, the emplacement of a series of plumes, each coupled with the emplacement of a 3-km-thick greenstone cover and a 10-km-thick sill results in ~ 20-km-thickness of TTG melt. My model incorporates delamination of restitic eclogite. Finally, I show that late granites in the Superior Province may have resulted from thickening of a crust that had been “pre-heated” during earlier arc activity and that prolonged granitic magmatism observed in some areas of the Superior Province may be explained by late underthrusting of fertile source rocks into deeper and hotter regions of the crust.
32

An Investigation of the ca. 2.7 Ga Late Archean Magmatic Event (LAME) in the Superior Province using 1-D Thermal Modelling

Ahmad, Seema 03 March 2010 (has links)
The Late Archean Magmatic Event (LAME), ca. 2.7 Ga, was the greatest crustal addition event in Earth history. My focus is the Superior Province of Canada, where LAME occurred ca. 2.75 – 2.65 Ga. Mantle plumes impinged on the Abitibi subprovince, where ~ 16 km regional thickness of tonalite-trondhjemite-granodiorite (TTG) melt was produced. Granites (sensu stricto) were the last magmatic phase of LAME, with a Superior-wide regional thickness of ~ 1 – 3 km. Assuming a crustal source for both TTG and granites, I use 1-D thermal models to investigate the origin of TTG in the Abitibi subprovince and that of late granites in the Superior Province. Melting curves appropriate to the source of TTG and granites are used to determine the thickness of melt produced in the models. I show that the incorporation of upward melt transfer into a standard model of lower crustal melting may increase the amount of predicted melt by ~ 1/(1-f), where f denotes the fraction of melt that is on average being extracted from the source rocks. Partitioning of heat producing elements between melt and restite reduces the amount of melt produced, but the effect is secondary compared to the increase in melt production through upward melt transfer. For the Abitibi subprovince, I show that the emplacement of a single plume coupled with the emplacement of a 12-km-thick greenstone cover can generate a maximum of ~ 9-km-thickness of TTG melt. However, the emplacement of a series of plumes, each coupled with the emplacement of a 3-km-thick greenstone cover and a 10-km-thick sill results in ~ 20-km-thickness of TTG melt. My model incorporates delamination of restitic eclogite. Finally, I show that late granites in the Superior Province may have resulted from thickening of a crust that had been “pre-heated” during earlier arc activity and that prolonged granitic magmatism observed in some areas of the Superior Province may be explained by late underthrusting of fertile source rocks into deeper and hotter regions of the crust.
33

Návrh parní odběrové kondenzační turbíny v Precheza, a.s. / Design of an extraction steam condensing turbine in the Precheza company.

Pavelka, Tomáš January 2009 (has links)
This diploma thesis is concerned with the design of the machinery with an extraction steam condensing turbine in Precheza corp. The theoretical part of this thesis describes the energetical situation in the company and the primary consideration about recovery of the heat, released at sulphuric acid production, for electrical power production. There is also presented brief description of the sulphuric acid production and the fundamental principles of the steam production at this process. In the practical part of this thesis there is performed the calculation of the heat-flow diagram of the steam turbine and the calculation of heat and producted electrical power at the basic operational states. There is presented the source code for the calculation of the heat-flow diagram using Matlab software. In the end there is mentioned the economical evaluation of the whole project, using the fundamental economical methods, such as net present value method, or profitability index, including the calculation of the pay-back period.
34

Srovnání energetických oběhů z pohledu jejich celkové účinnosti / Comparison of Energy Circles from point of view Efficiency

Houdek, Milan January 2010 (has links)
This diploma thesis investigates the combined production of power and heat from biomass. The main aim is to compare suggested energy circles in the light of their electric, general and economic efficiency. Introduction describes the basic terms and principles of energy utilization of biomass, combustion and gasification technology are described thoroughly. The main part contains suggestions and thermal calculations of energy circles. The thermal cycle with gasification chamber, combustion chamber and hot air turbine is proposed, than thermal cycle with gasification generator and cogeneration unit and finally Rankine-Clausius circle. In conclusion calculated results are recapitulated and the usability of proposed thermal cycles is assessed.
35

Termoregulace mravenců rodu Formica, konflikt jedince versus kolonie / Thermoregulation in ant genus Formica, an individual vs. colony conflict

Kadochová, Štěpánka January 2017 (has links)
This thesis deals with thermoregulation in red wood ants, in Formica rufa group. Our aim was to better understand the mechanisms by which red wood ants maintain thermal homeostasis in their nests. Red wood ants are known to keep high and stable temperatures in their nests from spring to autumn. Most emphasis is placed on the role of the nest mound as a solar collector or on a heat production by microbial community present in the nest material. However, some researchers believe that wood ants are able of active nest thermoregulation in which they can affect the nest temperature by behavioural reactions, mainly by sun basking, increased metabolic heat production or heat transport. The thesis consists of three research articles. The first one is focused on the timing of thermoregulation in red wood ants, the second one investigates in more detail one specific aspect of red wood ant thermoregulation - a sun basking behaviour. These two papers provide data from long-term field observations and experiments. The last paper is based on laboratory experiments where we tested a hypothesis resulting from field observations. Thanks to the field research we found out that ant activity (traffic on ant trails) significantly correlates with nest temperature; once the activity decreased the thermal homeostasis...

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