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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.
51

Molecular-beam epitaxial growth of low-dark-current avalanche photodiodes

Hurst, Jeffrey Byron, 1977- 29 August 2008 (has links)
The quaternary material system In[subscript x]Ga[subscript 1-x]As[subscript y]P[subscript 1-y] is an important material system for optoelectronic devices, specifically covering optimum fiber optic wavelengths. Among the limitations of using this material system concerning photodetector performance is generation of carriers due to material defects and impurities. This dissertation reports on the growth optimization of InGaAs using molecular-beam epitaxy for low-dark-current avalanche photodiodes through the study of the effects of the growth conditions on dark current. An optimum growth temperature of 545°C and arsenic beam equivalent pressure of 2x10⁻⁵ Torr was found for producing the lowest dark current density. Avalanche photodiodes were implemented with a dark current density 80 mA/cm² at 90% of the breakdown voltage.
52

Streaming potential measurements in sulfide rich tailings

El Husseini, Bassam. January 2008 (has links)
In general, tailings dams are expected to seep. Anomalous seepage, especially when induced by internal erosion, is a major concern for owners and operators. The long established techniques for monitoring water seepage provide sparse information which may not be sufficient to detect and map the seepage path. Hence, there exists a great need for non-invasive techniques that would be sensitive to changing seepage conditions. The non-invasive nature of the techniques is particularly important because drilling and other penetrating (invasive) investigation methods are normally avoided. / Non-invasive techniques such as self-potential and high-resolution resistivity have been significantly improved in the past decade and have been successfully used for water retention dam investigation and monitoring. The main difficulty in the use of these techniques in monitoring sulfide rich tailings dams is the presence of electrochemical potentials that renders the interpretation of the acquired self-potential data difficult. / Numerical modelling is one of the latest methods in interpreting self-potential anomalies induced by liquid flow. But, in order to model streaming potentials several parameters need to be measured or estimated; (1) the hydraulic driving force and the hydraulic conductivity are required to solve for the hydraulic pressure distribution; (2) the cross-coupling conductivity distribution is needed to calculate the conduction current source parameter; and (3) the resistivity distribution is needed to determine the resulting potential distribution. / The zeta-potential and the resistivity of three pyrite rich tailings from the Abitibi region in Quebec were measured over the pH range 2 to 5 in different KCl aqueous solutions for the purpose of estimating the magnitude of electrokinetic effect induced by mine water seepage and the electrical resistivity variation induced by particle migration. The experimental and theoretical results obtained in the present study are pertinent to the interpretation of self-potential data. The zeta-potential was found to vary from -27 to -2 mV and the resistivity of the tailings was found to increase when fine particles are eroded.
53

Conversion of electrical system from direct current to alternating current

Barr, Tandy Lee 05 1900 (has links)
No description available.
54

Modeling techniques for power system grounding systems

Papalexopoulos, Alexis D. 08 1900 (has links)
No description available.
55

An alternating current magnetothermoelectric heat pump

Wall, Donald Beatty 12 1900 (has links)
No description available.
56

Next generation of current sensors for aeronautics: preliminary designs

Babinet, Cyril 19 May 2008 (has links)
As a specialist in power distribution for the aerospace industry, Leach International-Europe intends to master both design and production of the current sensor - a strategic component - while offering a novel technology, free from important disadvantages of the previous generation. This report puts forward some research directions to replace the present generation, based on the Hall Effect and equipping most of commercial and military aircrafts. Relying on a feasibility study, and after reviewing the state of the art, this work heads quickly on exploiting Faraday's Law. The latter allows getting a voltage as an output directly from the magnetic field generated by the current flowing inside the conductor. The different solutions introduced here are based on analytical calculations (when it is possible), simulations and numerical calculations and are grounded on designing a sensor with an acceptable sensitivity.
57

Molecular-beam epitaxial growth of low-dark-current avalanche photodiodes

Hurst, Jeffrey Byron, January 1900 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.
58

Radiation from a small current loop in a magnetically uniaxial medium

Yim, Whijoon. January 1995 (has links)
Thesis (M.S.)--Ohio University, November, 1995. / Title from PDF t.p.
59

I. Resistance thermometry II. An experimental investigation of the possibility of using alternating current technique in the measurement of small temperature differences ...

Henry, Warren Elliott, January 1941 (has links)
Thesis (Ph. D.)--University of Chicago, 1941. / Lithoprinted. Includes bibliographical references.
60

A novel fault current limiter

Otete, Andrew. Li, Hui. January 1900 (has links)
Thesis (M.S)--Florida State University, 2004. / Advisor: Dr. Hui Li, Florida State University, College of Engineering, Dept. of Electrical and Computer Engineering. Title and description from dissertation home page (viewed May 20, 2005). Includes bibliographical references.

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