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Mechanics of Subglacial Hydrology under Supraglacial Lakes and Ice Stream Shear Margins

Thesis
Matheus C. Fernandes
Harvard University Archives, Masters of Engineering Thesis, Cambridge MA, May 2015
Publication year: 2015

Abstract

This thesis is broken down into two parts, both of which are focused on the mechanics of subglacial hydrology. The first part describes the opening behavior of a crack under a supraglacial lake, where a Finite Element Method model is presented to obtain the opening profile of a crack undergoing hydrostatic tension in an infinite power law creep material. The second part focuses on creating a numerical model for the opening diameter of Röthlisberger channels in ice stream shear margins, where antiplane strain rates are superimposed on in-plane stresses.

Design and Implementation of Wind Turbine Torque Measurement Device

Thesis
Matheus C. Fernandes
Case Western Reserve University Archives, Bachelor of Science in Engineering Thesis, Cleveland OH, December 2012
Publication year: 2012

Abstract

With the pursuit of understanding the torque on the shaft applied by the wind force on the blades, a torque measuring device was implemented to the turbine. This device is composed of two perpendicular strain gauges that measure continuous strain on the shaft. The orientation of the strain gauges gives measurement data on the torque as well as the RPM of the shaft. From these measurements we found a reverse torque phenomenon on the shaft when an emergency stop (e-stop) or the generator switches from low generation to high generation. This project uses wind data, and torque measurements data to analyze the effects created by the reverse torques on the shaft. This is a preliminary analysis to validate the need for a torque limiting device to be installed on the shaft. The device was designed to attach directly to the shaft as well as to withstand the brutal weather conditions that may occur in the nacelle.