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Seafloor hydrothermal systems play a key role in Earth fs energy and geochemical budgets. They also support the existence and development of complex chemosynthetic biological ecosystems that use the mineral-laden fluids as a source of energy and nutrients. This dissertation focuses on two inter-related topics: (1) heat output and geochemical fluxes at mid-ocean ridges, and (2) structural deformation of oceanic lithosphere related to subsurface serpentinization in submarine settings. The determination of heat output is important for several reasons. It provides important constraints on the physics of seafloor hydrothermal processes, on the nature of the heat sources at mid-ocean ridges, and on nutrient transport to biological ecosystems. Despite its importance, measurements of hydrothermal heat outputs are still scarce and cover less than 5% of active hydrothermal vent sites. In this work, we report development of two new devices designed to measure fluid flow velocities from the submersible at temperatures of up to 450 C and depths 5,000 m. By using these instruments on 24 Alvin dives, new measurements of hydrothermal heat output have been conducted at the Juan de Fuca Ridge, including first measurements from the High Rise and Mothra hydrothermal fields. The collected data suggest that the high-temperature heat output at the Main Endeavour Field (MEF) may be declining since the 1999 eruption. The flow measurement results, coupled with in-situ geochemical measurements, yielded the first estimates of geochemical fluxes of volatile compounds at MEF and Mothra. Our findings indicate that geochemical flux from diffuse flows may constitute approximately half of the net geochemical flux from Juan de Fuca Ridge. It has recently been recognized that serpentinization of mantle peridotites, due to its exothermic nature, may be a mechanism contributing to the heat output at mid-ocean ridges. The tectonic response of the crust to serpentinization of extensively distributed peridotites at mid-ocean ridges and subduction zones could provide a means of characterizing serpentinized regions in the oceanic lithosphere. These regions are often associated with surface topographic anomalies that may result from the volume expansion caused by the serpentinization reactions. Although there is a clear correlation between tectonics and serpentinization, the link is complex and still not understood. In this dissertation, we calculated the transformation strain and surface uplift associated with subsurface serpentinization of variously shaped ultramafic inclusions. Application of the results to explain the anomalous topographic salient at the TAG hydrothermal field (Mid-Atlantic Ridge) suggests that this feature may result from a serpentinized body beneath the footwall of a detachment fault. Because the depth of the potential serpentinized region appears to be more than 1.5 times the size of the inclusion, the uplift profile is relatively insensitive to the exact location or shape of the serpentinized domain. The rate of exothermic heat release needed to produce the serpentinized volume may contribute to the ongoing diffuse flow. Application of the results to an uplift feature associated with the Kyushu ]Palau subduction zone in the western Pacific, shows that approximately 3% transformational strain in an inclined serpentinized region of the mantle wedge near the subducted Kyushu ]Palau Ridge may result in the observed uplift on the Miyazaki Plain. Using the uplift data may help to constrain the level of the subsurface serpentinization.

<p>U disertaciji je prikazan i predložen novi metod merenja snage<br />i energije vetra koji se bazira na stohastičkoj digitalnoj mernoj<br />metodi (SDMM), umesto do sada korišćene standardne sempling<br />metode (SSM). Standard za merenje brzine vetra predstavlja<br />anemometar sa šoljicama, koji na svom izlazu daje sinusni napon<br />čija su amplituda i frekvencija linearno zavisne od brzine<br />vetra. Kako su snaga i energija vetra proporcionalne trećem<br />stepenu brzine vetra, u tu svrhu se primenjuje generalizovan<br />hardver namenjen za računanje proizvoda tri ulazna signala. Zbog<br />niskog frekvencijskog opsega ulaznog signala izvršeno je<br />značajno pojednostavljenje hardvera mernog uređaja. Teorijskom<br />analizom, simulacijom, a potom i eksperimentom potvrđena je<br />hipoteza istraživanja, da se SDMM uspešno može koristiti za<br />merenje snage i energije vetra.</p> / <p>In this dissertation а new wind power and energy measurement<br />method, based on Stochastic Digital Measurement Method (SDMM),<br />was elaborated and proposed, to replace the commonly used Standard<br />Sampling Method (SSM). The standard for wind speed measurement is<br />a cup anemometer that provides a sinusoidal voltage on its output,<br />having the amplitude and frequency linearly dependent of the wind<br />speed. Since the wind power and energy are proportional to the third<br />degree of the wind speed, the general case hardware has been designed<br />for the product calculation over three input signals. The low frequency<br />range of the input signal allows for a significant simplification of the<br />measuring instrument hardware. By theoretical analysis and<br />simulation, and consequently through an experiment the hypothesis of<br />this research was confirmed - that SDMM can be successfully used to<br />measure wind power and energy.</p>