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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.
181

Cykelbanors bredd och cyklisters beteende : En metod för att uppskatta cyklisters upplevda risknivåer på olika bredder av cykelbanor / Bike lane width and cyclists’ behaviour : A method for assessing cyclists' perceived risk levels on bidirectional bike lanes

Egeskog, Johan January 2019 (has links)
The aim of this study was to investigate different standards of bidirectional bike lanes and investigate if they provide enough space for the needs of cyclists. A method was developed for evaluating cyclists’ behaviour using the theory of risk homeostasis and two risk-factors; speed and sideways position. An experimental design was also constructed and the results from the subsequent experiment implies that the two chosen risk markers could be useful in future studies relating to the design of bicycle infrastructure. A significant difference in the positioning of cyclists was found on different bike lane widths. The risk markers for sideways position show significant results at bidirectional bike lane widths below 2.4 meters. At such widths, cyclists seem to actively position themselves closer to the curb in the presence of oncoming cyclists. This is interpreted as a risk compensation which indicates that cyclists are not completely comfortable on that standard of bike lane. A conclusion would be to view bidirectional bike lanes at 2.4 meters width on flat surfaces, with adequate safety-zones beside the bike lanes, as a good standard for regular cyclists in many situations. More widening is not believed to provide major additional experienced safety or passability until the width allow for safe overtaking in the presence of oncoming cyclists. / Syftet med denna studie var att undersöka olika standarder av cykelbanor och se om de tillgodoser cyklisternas utrymmesbehov. En metod utvecklades för att utvärdera cyklisters beteende på olika standarder av dubbelriktade cykelbanor med hjälp av riskhomeostasteorin och två riskmarkörer; sidledsposition och hastighet. En experimentdesign utvecklades och experimentet genomfördes. Resultaten tyder på att metoden fungerar och kan vara till nytta i framtida studier gällande cyklisters behov, relaterat till designen av cykelinfrastruktur. Resultaten visar att cyklisterna placerar sig längre från kanten på cykelbanan ju bredare den är. En statistiskt signifikant skillnad i sidledsposition uppmättes också vid möten av andra cyklister när bredden på cykelbanan sjönk till under 2,4 meter. Vid dessa bredder placerade sig cyklisterna aktivt närmare kanten vid möten. Resultatet tolkas som en form av riskkompensation och indikerar att cyklisterna inte är helt trygga på cykelbanor av den bredden. Slutsatsen blir att vi kan betrakta 2,4 meter breda, dubbelriktade cykelbanor på horisontella ytor med tillräckliga säkerhetsavstånd till hinder vid sidan av cykelbanan som en god standard för många förhållanden. Ytterligare breddning tordes inte ge några större upplevda säkerhets- eller framkomlighetsfördelar förrän bredden tillåter säkra omkörningar även vid möten.
182

A Study of Shock Analysis Using the Finite Element Method Verified with Euler-Bernoulli Beam Theory; Mechanical Effects Due to Pulse Width Variation of Shock Inputs; and Evaluation of Shock Response of a Mixed Flow Fan

Gonzalez Campos, David Jonathan 01 October 2014 (has links) (PDF)
A Study Of Shock Analysis Using The Finite Element Method Verified With Euler-Bernoulli Beam Theory; Mechanical Effects Due To Pulse Width Variation Of Shock Inputs; And Evaluation Of Shock Response Of A Mixed Flow Fan David Jonathan González Campos For many engineers that use finite element analysis or FEA, it is very important to know how to properly model and obtain accurate solutions for complicated loading conditions such as shock loading. Transient acceleration loads, such as shocks, are not as common as static loads. Analyzing these types of problems is less understood, which is the basis for this study. FEA solutions are verified using classical theory, as well as experimental results. The complex loading combination of shock and high speed rotation is also studied. Ansys and its graphic user interface, Workbench Version 14.5, are the programs used to solve these types of problems. Classical theory and Matlab codes, as well as experimental results, are used to verify finite element solutions for a simple structure, such as a cantilevered beam. The discrepancy of these FEA results is found to be 2.3%. The Full Method and the Mode Superposition Method in Ansys are found to be great solution tools for shock loading conditions, including complex acceleration and force conditions. The Full Method requires less pre-processing but solutions could take days, as opposed to hours, to complete in comparison with the Mode Superposition Method, depending on the 3D Model. The Mode Superposition Method requires more time and input by the user but solves relatively quickly. Furthermore, a new representation of critical pulse width of the shock inputs is presented. Experimental and finite element analyses of a complete mixed flow fan undergoing ballistic shock is also completed; deformation results due to shock loading, combined with rotation and aerodynamic loading, account for 32.3% of the total deformation seen from experimental testing. Solution methods incorporated in Ansys, and validation of FEA results using theory, have great potential implications as powerful tools for engineering students and practicing engineers.
183

Determining the effective width of composite beams with precast hollowcore slabs

El-Lobody, E., Lam, Dennis January 2005 (has links)
This paper evaluates the effective width of composite steel beams with precast hollowcore slabs numerically using the finite element method. A parametric study, carried out on 27 beams with different steel cross sections, hollowcore unit depths and spans, is presented. The effective width of the slab is predicted for both the elastic and plastic ranges. 8-node three-dimensional solid elements are used to model the composite beam components. The material non-linearity of all the components is taken into consideration. The non-linear load-slip characteristics of the headed shear stud connectors are included in the analysis. The moment-deflection behaviour of the composite beams, the ultimate moment capacity and the modes of failure are also presented. Finally, the ultimate moment capacity of the beams evaluated using the present FE analysis was compared with the results calculated using the rigid – plastic method.
184

Development and evaluation of an automated system to deliver a live-attenuated Edwardsiella ictaluri vaccine in commercial catfish production systems

Lowe, John Wesley 13 December 2019 (has links)
Catfish aquaculture is the largest cultured food fish industry in the United States, accounting for approximately $375 million in sales annually, with Mississippi leading the industry with 36,200 surface acres of production. However, infectious diseases such as enteric septicemia of catfish (ESC) are decreasing production efficiencies, creating losses of $40-60 million annually. Live-attenuated oral ESC vaccines are effective in preventing ESC infections, but have not been widely adopted by the catfish industry due to the lack of a system to administer the oral vaccine at the scale seen in commercial catfish production systems. An automated system was developed to administer a dosage of 220.5 ml of a live-attenuated ESC vaccine per kg of catfish feed, adapting commercial catfish feeder design to include a screw conveyor for mixing vaccine and feed in a continuous process, pulse-width modulated spray nozzle control for precise vaccine application, and a programmable automation controller to regulate and monitor system performance. Initial performance evaluations demonstrated system operation within the desired design specifications. System feed rates were determined to be a function of the rotational speed (RPM) of the screw conveyor and to be linear across the operational range. Feed rates were observed to decrease by 45% over dry feed when applying liquid vaccine to the feed stream at the 220.5 ml/kg (100 ml/lb) rate, resulting in a feed rate range of 6.80-34.02 kg/min (15-75 lb/min) (95% CI). Uniform pellet-level vaccine distribution is crucial to efficacy as pellet consumption is directly correlated with fish size, with more criticality in smaller fish fed at low rates. Pellet vaccine concentrations at 6.80, 20.41, and 34.02 ml/kg were highly variable and vaccine application at all rates were observed to be statistically different (less) than the target 220.5ml/kg rate (95% CI), pointing to potential issues with vaccine delivery system configuration or inadequacies in sampling methodology. Further evaluation at the pellet level with live-attenuated vaccine to obtain viable cell counts within individual pellets would provide data necessary to address uniformity of coverage questions more fully and to develop operational protocols that maximize system capabilities and vaccine efficacy.
185

Longitudinal Shear Capacity of the Slabs of Composite Beams

El-Ghazzi, Mohammed Nael 11 1900 (has links)
No abstract is provided. / Thesis / Master of Engineering (MEngr) / Scope and contents: In this report, a method for calculating the longitudinal shear capacity of the slab of simply-supported steel-concrete composite beams is presented. The method is based on analysing the stresses at failure of the concrete elements located at the slab shear surface. In this analysis, the slab width and the shear span are found to be two main parameters that have been neglected in the empirical solutions previously adopted.
186

Large Scale Computer Investigations of Non-Equilibrium Surface Growth for Surfaces from Parallel Discrete Event Simulations

Verma, Poonam Santosh 08 May 2004 (has links)
The asymptotic scaling properties of conservative algorithms for parallel discrete-event simulations (e.g.: for spatially distributed parallel simulations of dynamic Monte Carlo for spin systems) of one-dimensional systems with system size $L$ is studied. The particular case studied here is the case of one or two elements assigned to each processor element. The previously studied case of one element per processor is reviewed, and the two elements per processor case is presented. The key concept is a simulated time horizon which is an evolving non equilibrium surface, specific for the particular algorithm. It is shown that the flat-substrate initial condition is responsible for the existence of an initial non-scaling regime. Various methods to deal with this non-scaling regime are documented, both the final successful method and unsuccessful attempts. The width of this time horizon relates to desynchronization in the system of processors. Universal properties of the conservative time horizon are derived by constructing a distribution of the interface width at saturation.
187

Speckle Statistics of Articulating Objects

Conrad III, Dallis G. 08 November 2011 (has links)
No description available.
188

Design and Modeling of High Performance LED Dimming Driver with Reduced CurrentSpikes using Turn-On Snubber across Power MOSFET

Borra, Venkata Shesha Vamsi 17 June 2014 (has links)
No description available.
189

Large-Signal Analysis of Buck and Interleaved Buck DC-AC Converters

Dey, Sourav 15 September 2014 (has links)
No description available.
190

Incoherent Scatter Radar Study of the Ionospheric D-region

Ma, Zheng 14 July 2015 (has links)
No description available.

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