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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.
11

The Contributions of Grace Murray Hopper to Computer Science and Computer Education

Mitchell, Carmen L. (Carmen Lois) 05 1900 (has links)
This study explored the life and work of the late Grace Murray Hopper, Rear Admiral United States Naval Reserve. The study emphasized Hopper's contributions to computer science and computer science education, including her philosophy of teaching and learning, and her pedagogical legacy for today's teachers and scholars of computer science and computer science education.
12

Design of fish feeding mechanism for Recirculation Aquaculture System (RAS) / Utformning av fiskmatningsmekanism för återcirkulation av vattenbrukssystem

SIVAKUMAR, NITHIN January 2020 (has links)
Fish farming or Aquaculture is a growing food-producing industry to culture the fish in artificially constructed tanks. A large number of fishes are reared in tanks for 100-150 days and produce food for the population. With increasing population and declining worldwide capture fishery, Aquaculture is perceived as a potential technique to meet the ever-expanding food demand without tarnishing the aquatic food chain. However, problems which are addressed in current systems like human intervention and unused feed material inhibit the production rate. This thesis provides methods and guidelines to resolve the challenges and simplify the mechanical design aspects of storage, transportation, and control of the dispensing process, which ultimately benefits the small-scale producers and entrepreneurs. Storing and distributing the fish feed along the fluid stream involves in considering multi-disciplinary engineering calculations. The fundamental knowledge of fluid mechanics, discrete element properties and mechanical design have been found to be an effective solution for such challenges. The results of this work provide information on designing the fish feeding mechanism incorporating fluid stream particle dispensing and evaluation of components present in the system. The thesis work provides solutions that serve as a starting point for low-cost design, validation and automation of components in a feeding mechanism for aquaculture industries. / Fiskodling eller vattenbruk är en växande livsmedelsproducerande industri för att odla fisk i konstgjorda tankar. Ett stort antal fiskar uppföds i tankar i 100-150 dagar och producerar mat för befolkningen. Med ökande befolkning och minskande världsfångstfiske uppfattas vattenbruk som en potentiell teknik för att möta den ständigt växande efterfrågan på livsmedel utan att skada vattenlevande livsmedelskedjan. Emellertid hämmar problem som tas upp i nuvarande system som mänsklig intervention och oanvänt foderråvara produktions hastigheten. Denna avhandling ger metoder och riktlinjer för att lösa utmaningarna och förenkla de mekaniska designaspekterna av lagring, transport och kontroll av utmatning processen, vilket i slutändan gynnar småskaliga producenter och entreprenörer. Lagring och distribution av fiskfoder längs vätskeflödet innebär att man överväger tvärvetenskapliga tekniska beräkningar. Den grundläggande kunskapen om fluidmekanik, diskreta element egenskaper och mekanisk design har visat sig vara en effektiv lösning för sådana utmaningar. Resultaten av detta arbete ger information om utformningen av fiskmatning mekanismen som innehåller vätskeflöde partikeldosering och utvärdering av komponenter som finns i systemet. Examensarbetet tillhandahåller lösningar som fungerar som utgångspunkt för lågkostnads konstruktion, validering och automatisering av komponenter i en utfodringsmekanism för vattenbruksindustrin.
13

Stress distributions in silos and hoppers

O'Neill, James Christopher January 2013 (has links)
This thesis provides a report on the numerical analysis of stress distributions within granular materials held in silos and hoppers. Stress distributions within granular materials stored in silos and hoppers have been the subject of research for over 100 years, work starting in this field in 1895 (Janssen). Knowledge of stress distributions within the granular materials contained is essential to allow structural design of the silo and hopper shell and attachments, and to allow estimation of likelihood and location of cohesive arch formation. National design codes for silos and hoppers (including BS EN 1993-4-1:2007 Eurocode 3 and DIN 1055-6:2005-03) are based on approximate techniques that assume vertical and horizontal directions of principal stresses, with constant horizontal stress across the silos. According to the knowledge of the author there are no industrial standards that allow calculation of loading on inserts within hoppers. The objective of the research project is to develop algorithms to predict stresses in hoppers and silos using principal stress arc geometry methods, and implementation of these methods in various silo and hopper configurations including those with inserts for the purposes of aiding flow. The research project algorithms are spreadsheet- and QB64 platform-based, and are able to produce stress distributions within silos and hoppers. This is achieved by extension of the principal stress arc method of analysis. The new algorithms allow prediction of common flow problems and provide new information on structural loading of silos and hoppers, including inserts used to promote flow. The research project models allow estimation of azimuthal stresses within three-dimensional case studies.
14

Cost Estimation and Production Evaluation for Hopper Dredges

Hollinberger, Thomas E. 2010 May 1900 (has links)
Dredging projects are expensive government funded projects that are contracted out and competitively bid upon. When planning a trailing suction hopper dredge project or bidding on the request for proposal for such a project, having an accurate cost prediction is essential. This thesis presents a method using fluid transport fundamentals and pump power characteristics to determine a production rate for hopper dredges. With a production rate established, a number of financial inputs are used to determine the cost and duration of a project. The estimating program is a Microsoft Excel spreadsheet provided with reasonable values for a wide arrange of hopper dredging projects. The spreadsheet allows easy customization for any user with specific knowledge to improve the accuracy of his estimate. Results from the spreadsheet were found to be satisfactory using the default values and inputs of 8 projects from 1998 to 2009,: The spreadsheet produced an estimate that was an average of a 15.9% difference from the actual contract cost, versus a 15.7% difference for government estimates of the same projects.
15

Cost Estimation and Production Evaluation for Hopper Dredges

Hollinberger, Thomas E. 2010 May 1900 (has links)
Dredging projects are expensive government funded projects that are contracted out and competitively bid upon. When planning a trailing suction hopper dredge project or bidding on the request for proposal for such a project, having an accurate cost prediction is essential. This thesis presents a method using fluid transport fundamentals and pump power characteristics to determine a production rate for hopper dredges. With a production rate established, a number of financial inputs are used to determine the cost and duration of a project. The estimating program is a Microsoft Excel spreadsheet provided with reasonable values for a wide arrange of hopper dredging projects. The spreadsheet allows easy customization for any user with specific knowledge to improve the accuracy of his estimate. Results from the spreadsheet were found to be satisfactory using the default values and inputs of 8 projects from 1998 to 2009,: The spreadsheet produced an estimate that was an average of a 15.9% difference from the actual contract cost, versus a 15.7% difference for government estimates of the same projects.
16

Factors influencing vigilance while feeding in reintroduced California condors (Gymnogyps californianus) /

West Christopher J. January 1900 (has links)
Thesis (M.S.)--Humboldt State University, 2009. / Includes bibliographical references (leaves 29-35). Also available via Humboldt Digital Scholar.
17

The New York artist as social critic, 1918-1933

Cox, Richard, January 1973 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1973. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
18

Using the Phase Angle Oscillator Controller for Hopping Robots

January 2015 (has links)
abstract: As the robotic industry becomes increasingly present in some of the more extreme environments such as the battle field, disaster sites or extraplanetary exploration, it will be necessary to provide locomotive niche strategies that are optimal to each terrain. The hopping gait has been well studied in robotics and proven to be a potential method to fit some of these niche areas. There have been some difficulties in producing terrain following controllers that maintain robust, steady state, which are disturbance resistant. The following thesis will discuss a controller which has shown the ability to produce these desired properties. A phase angle oscillator controller is shown to work remarkably well, both in simulation and with a one degree of freedom robotic test stand. Work was also done with an experimental quadruped with less successful results, but which did show potential for stability. Additional work is suggested for the quadruped. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2015
19

Common Insect Contaminants Found in Arizona Lettuce

Kerns, David L. 02 1900 (has links)
2 pp. / This publication describes the common insects found in Arizona lettuce through the use of pictures. The insects include; lepidopterous larva, striped flea beetle, leafminer fly, leafminer mine, adult western flower thrips, winged adult aphid, false chinch bug, lygus bug, potato leafhopper, and threecornered alfalfa hopper.
20

Trajectory design, optimisation and guidance for reusable launch vehicles during the terminal area flight phase.

Chartres, James T. A. January 2007 (has links)
The next generation of reusable launch vehicles (RLVs) require significant improvements in guidance methods in order to reduce cost, increase safety and flexibility, whilst allowing for possible autonomous operation. Research has focused on the ascent and hypersonic re-entry flight phases. This thesis presents a new method for trajectory design, optimisation and guidance of RLVs during the terminal area flight phases. The terminal area flight phase is the transitional phase from hypersonic re-entry to the approach and landing phase. The trajectory design, optimisation and guidance methods within this thesis are an evolution of previous work conducted on the ascent and re-entry flight phases of RLVs. The methods are modified to incorporate the terminal area flight phase through the adaption of the problem definition and the inclusion of the speed brake setting as a steering parameter. The methods discussed and developed in this thesis are different to previous methods for the terminal area flight phase as they encompass optimisation, trajectory design and guidance based on the definition of the steering parameters. The NLPQL nonlinear optimiser contained within the International Mathematics Standards Library (IMSL) is utilised for trajectory design and optimisation. Real-time vehicle guidance is achieved using the restoration steps of an accelerated Gradient Projection Algorithm (GPA). The methods used are evaluated in a three degrees of freedom (3DOF) simulation environment. To properly evaluate the programs and gain a better understanding of the terminal area flight phase, two different vehicles are utilised within this study. These vehicles are the German sub-orbital Hopper concept vehicle, a previously proposed replacement for the Ariane series of launch vehicles and the recently cancelled joint National Aeronautics and Space Administration (NASA) and Lockheed Martin sub-orbital test bed vehicle, X-33. The two vehicles each have a terminal area flight phase, but their mission profiles and vehicle characteristics are significantly different. The Hopper vehicle is a winged re-entry vehicle, whereas the X-33 vehicle is a lifting body. The trajectory design method takes into account the initial and final conditions, in-flight restrictions such as dynamic pressure and vehicle loads as well as safety margins. The designed trajectories are evaluated to analyse the terminal area flight phase and to assist in the development of the guidance program. The guidance method is evaluated utilising an program consisting of two parts, a real world simulator with high order models and a representation of the on-board guidance computer, the predictor, which uses low order models for computational efficiency. The guidance method is evaluated against a variety of off-nominal conditions to account for dispersions within the high order real world models and common errors experienced by re-entry vehicles. These off-nominal conditions include atmospheric disturbances, winds, aerodynamic, mass, navigation, steering and initial condition errors. The results of this study include a detailed analysis of the terminal area flight phase highlighting the major influences for vehicle and trajectory design. The study also confirms the applicability of the non-linear programming method utilising the vehicle steering parameters as a viable option for trajectory design and guidance. A comparison to other available results highlights the strengths and weaknesses of the proposed method. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1282342 / Thesis (Ph.D.)--School of Mechanical Engineering, 2007.

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