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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.
21

The synthesis of point data and path data in estimating sofar speed

Johnson, Rockne Hart January 1968 (has links)
Typescript. / Thesis (Ph. D.)--University of Hawaii, 1968. / Bibliography: leaves [31]-32. / v, 32 l maps, graphs
22

High speed signal compensation on printed circuit boards

Boos, Bernie 11 February 2004
Data transfer rates on printed circuit boards are quickly approaching speeds that challenge the limits of todays technology. Inter-chip communication has increased dramatically. Currently data rates have reached 3.125 Gb/s on standard circuit board, but chip-to-chip digital communication has currently reached a plateau and several problems need to be addressed to significantly increase data transfer rates. Inductive and capacitive components of far end crosstalk (FEXT) conveniently cancel each other as they propagate on an interconnect transmission line, however the inductive and capacitive components of near end crosstalk(NEXT) add together and interfere with signals on adjacent receivers.<p>This paper proposes a novel solution for canceling crosstalk by adding extra circuitry to the receiver within the integrated circuit. This digital circuit delivers one of three appropriate levels of crosstalk compensation to the incoming signal. Since the circuit is digital, simple blocks can be used to implement it on a complimentary metal-oxide semiconductor (CMOS) integrated circuit and consume very little extra silicon.<p>This paper presents the compensation circuit and reports the results of the simulations, which demonstrate improved performance over the standard system. The compensation circuit is specifically aimed at adjacent input and output lines on a microchip. Simulations of a typical circuit board configuration operation have shown crosstalk that is only 15 dB lower than a received attenuated signal. The crosstalk cancellation circuit has been shown to improve this by as much as 10 dB.
23

Effects of multiple wires and welding speed on the microstructures and properties of submerged arc welded X80 steel

Farhat, Hanan Alsharef 11 September 2007
Currently, the demand for natural gas is increasing as a result of high world energy consumption and rising environmental awareness. As the exploration of natural gas field is expanding towards remote regions, long distance pipelines have been developed. The economical, environmental, and safe movement of gas to the marketplace requires that transmission pipelines designed to operate at high pressure should possess adequate strength and improved toughness over a variety of temperature ranges. The purpose of this research was to investigate the effect of submerged arc welding (SAW) parameters on the quality and mechanical properties of X80 steel, which was supplied by IPSCO Inc., Regina. The welding was performed using single and double wires and different speeds (16.93, 19.69, 25.4, 29.63 and 33.87mm/s). The weld quality was evaluated using non-destructive testing methods (NDT) such as visual inspection, radiography, and ultrasonic test. The weld bead characteristics were studied using weld geometry measurements. The relationship between the microstructures and mechanical properties of weld deposits was studied by means of hardness measurements, Charpy V-notch test, lateral expansion measurements, tensile test, optical metallography, image analysis, scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS).<p>It was found that there was a limit to which welding speed could be increased without the weld suffering from severe defects such as lack of penetration and undercut. The use of more than one welding wire improved the maximum welding speed at which good weld quality was maintained. Increasing the welding speed resulted in changes in the weld microstructure through the formation of higher percentage of fine acicular ferrite (AF) grain structure and a reduction in the amount of grain boundary ferrite (GBF) in the weld metal. Changing weld speed also reduced the size of the heat affected zone (HAZ). All of this resulted in improved the mechanical properties of the welded joints.
24

High speed signal compensation on printed circuit boards

Boos, Bernie 11 February 2004 (has links)
Data transfer rates on printed circuit boards are quickly approaching speeds that challenge the limits of todays technology. Inter-chip communication has increased dramatically. Currently data rates have reached 3.125 Gb/s on standard circuit board, but chip-to-chip digital communication has currently reached a plateau and several problems need to be addressed to significantly increase data transfer rates. Inductive and capacitive components of far end crosstalk (FEXT) conveniently cancel each other as they propagate on an interconnect transmission line, however the inductive and capacitive components of near end crosstalk(NEXT) add together and interfere with signals on adjacent receivers.<p>This paper proposes a novel solution for canceling crosstalk by adding extra circuitry to the receiver within the integrated circuit. This digital circuit delivers one of three appropriate levels of crosstalk compensation to the incoming signal. Since the circuit is digital, simple blocks can be used to implement it on a complimentary metal-oxide semiconductor (CMOS) integrated circuit and consume very little extra silicon.<p>This paper presents the compensation circuit and reports the results of the simulations, which demonstrate improved performance over the standard system. The compensation circuit is specifically aimed at adjacent input and output lines on a microchip. Simulations of a typical circuit board configuration operation have shown crosstalk that is only 15 dB lower than a received attenuated signal. The crosstalk cancellation circuit has been shown to improve this by as much as 10 dB.
25

Effects of multiple wires and welding speed on the microstructures and properties of submerged arc welded X80 steel

Farhat, Hanan Alsharef 11 September 2007 (has links)
Currently, the demand for natural gas is increasing as a result of high world energy consumption and rising environmental awareness. As the exploration of natural gas field is expanding towards remote regions, long distance pipelines have been developed. The economical, environmental, and safe movement of gas to the marketplace requires that transmission pipelines designed to operate at high pressure should possess adequate strength and improved toughness over a variety of temperature ranges. The purpose of this research was to investigate the effect of submerged arc welding (SAW) parameters on the quality and mechanical properties of X80 steel, which was supplied by IPSCO Inc., Regina. The welding was performed using single and double wires and different speeds (16.93, 19.69, 25.4, 29.63 and 33.87mm/s). The weld quality was evaluated using non-destructive testing methods (NDT) such as visual inspection, radiography, and ultrasonic test. The weld bead characteristics were studied using weld geometry measurements. The relationship between the microstructures and mechanical properties of weld deposits was studied by means of hardness measurements, Charpy V-notch test, lateral expansion measurements, tensile test, optical metallography, image analysis, scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS).<p>It was found that there was a limit to which welding speed could be increased without the weld suffering from severe defects such as lack of penetration and undercut. The use of more than one welding wire improved the maximum welding speed at which good weld quality was maintained. Increasing the welding speed resulted in changes in the weld microstructure through the formation of higher percentage of fine acicular ferrite (AF) grain structure and a reduction in the amount of grain boundary ferrite (GBF) in the weld metal. Changing weld speed also reduced the size of the heat affected zone (HAZ). All of this resulted in improved the mechanical properties of the welded joints.
26

Investigation of 50 km/h speed zone :

Nalluri, Gopi Krishna Unknown Date (has links)
To date, the 50 km/h General Urban Speed Limit (GUSL) has been implemented to some local residential streets in the City of Port Adelaide Enfield (hereafter referred to as Port Adelaide), South Australia as a Local Area Traffic Management (LATM) scheme since March 2003 aiming to reduce travel speeds and traffic volumes so as to enhance road safety and amenity of residential areas. Port Adelaide is located approximately nine kilometres away from the North-west of Adelaide Central Business District (CBD). There are major express highways and freight roads enclosing Port Adelaide, and within the boundaries is composed of many arterial and collector roads. All of these arterial roads and some major collector roads line in north-south direction. As a result of these geographical characteristics, Port Adelaide is a city covering the major direct routes for residents and major freight route for goods transport in the north-west suburbs. / However, one of the problems occurring in Port Adelaide seems to be characteristics of grid road networks lacking clear road hierarchy, which can be seen from many local streets connecting directly with nearby arterial and/or collector roads. Furthermore, as described previously Port Adelaide consists of many freight routes, arterial routes, and these characteristics cause another problem. Traffic is induced to divert to local streets, which are relatively straight, and uses them as an alternative route causing many problems to residents in the local area due to travel demands during rush hour. To this point, it can be seen that the 50 km/h GUSL scheme might not be as efficient as it should be in deterring through traffic since the implementation of traffic management has not covered a macro scale, which in this case is arterial roads forming a connective grid. / This study seeks to present the analysis of traffic data in terms of traffic volumes, mean speed and 85th percentile on three different local residential streets during weekday and soma crash data analysis is also done on two study streets. The expected results of this study may be taken as samples for further research in future. / Thesis (MTransportSysEngineering)--University of South Australia, 2006.
27

Design of Optimal Coasting Speed for MRT Systems by Considering Social Cost

Hsieh, Ching-Ho 09 July 2006 (has links)
The Mass Rapid Transit (MRT) systems have been built in many metropolitans to solve the public transportation problem such as traffic congestion. With such high investment cost, it is important to design a proper operation strategy to reduce the operational cost which achieving the system performance. With less ridership as compared to Taipei MRT system, the minimization of social cost which consists of energy consumption and the traveling time to complete the journey, has been investigated for Kaohsiung MRT (KMRT) system. By this way, the optimal coasting speed between train stations is solved according to the ridership and distance between the stations. The artificial neural network (ANN) has proposed in this thesis to determine the optimal coasting speed of the train set. The energy consumption and the traveling time to complete the journey between stations with various riderships are calculated by exactly the train performance simulation to generate the training data set. The objective function is defined by considering the energy consumption and the traveling time cost of passengers. By performing the ANN training, the ANN model is therefore obtained, which can be used to solve the optimal coasting speed of train sets. To demonstrate the effectiveness of the proposed ANN model, the forecasting of annual ridership for both Orange Line and Red Line of KMRT system is used. The optimal coasting speed and the corresponding profile of power consumption have been solved to minimize the social cost of MRT systems operation.
28

Aerodynamic coefficients of a symmetrical airfoil in an oscillating flow

Chamberlain, George A. January 1990 (has links) (PDF)
Thesis (M.S. in Aeronautical Engineering)--Naval Postgraduate School, September 1990. / Thesis Advisor(s): Miller, James A. Second Reader: Schmidt, Louis V. "September 1990." Description based on title screen viewed on December 17, 2009. DTIC Descriptor(s): Velocity, angles, air flow, angle of attack, airfoils, cycles, time, surfaces, three dimensional, flow rate, coefficients, symmetry, pressure, axes, aerodynamic characteristics, value, unsteady flow, drag, oscillation, free stream, static pressure, pressure distribution, plotting, steady flow, control. DTIC Identifier(s): Airfoils, oscillating flow, pressure measurement, turbulence, moments, aerodynamic lift, aerodynamic drag, aerodynamic coefficients, wind tunnel tests, rotor blades(rotary wings), random variables, symmetrical airfoils, theses. Author(s) subject terms: Oscillating flow, aerodynamic coefficients, symmetrical airfoil. Includes bibliographical references (p. 94). Also available in print.
29

A diagnostic study of the velocity structure of a meandering jet using a primitive equation model with dynamic mode initialization

de Jesus, Roland E. January 1990 (has links) (PDF)
Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, September 1990. / Thesis Advisor(s): Haney, R. L. ; Stanton, T. P. "September 1990." Description based on title screen viewed on December 17, 2009. DTIC Descriptor(s): Ocean currents, *fronts (oceanography), diagnosis(general), California, transitions, theses, mathematical models, vertical orientation. DTIC Identifier(s): California current, CTZ (California transition zone). Author(s) subject terms: Diagnostic model, California Current, CTZ, dynamical modes. Includes bibliographical references (p. 64-66). Also available in print.
30

Sur les vitesses relatives de la lumière dans l'air et dans l'eau

Foucault, Léon January 1900 (has links)
Thèse : Sciences physiques : Paris, Faculté des sciences : 1853. / Titre provenant de l'écran-titre.

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