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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

Specifications extraction and synthesis: Their correlations with preliminary design.

Umaretiya, Jagdish R. January 1990 (has links)
This report addresses the research applied towards the automation of the engineering design process, in particular the structural design process. The three important stages of the structural design process are: the specifications, preliminary design and the detailed design. An iterative redesign architecture of the structural design process lends itself to automation. The automation of the structural design can improve both the cost and the reliability, and enhance the productivity of the human designers. To the extent that the assumptions involved in the design process are explicitly represented and automatically inforced, the design errors resulting from the violated assumptions can be avoided. Artificial Intelligence (AI) addresses the automation of complex and knowledge-intensive tasks such as the structural design process. It involves the development of the Knowledge Based Expert System (KBES). There are several tools, also known as expert shells, and languages available for the development of knowledge-based expert systems. A general purpose language, called LISP, is very popular among researchers in AI and is used as an environmental tool for the development of the KBES for the structural design process. The resulting system, called Expert-SEISD, is very generic in nature. The Expert-SEISD is composed of the user interface, inference engine, domain specific knowledge and data bases and the knowledge acquisition. The present domain of the Expert-SEISD encompasses the design of structural components such as beams and plates. The knowledge acquisition module is developed to facilitate the incorporation of new capabilities (knowledge or data) for beams, plates and for new structural components. The decision making is an integral part of any design process. A decision-making model suitable for the specifications extraction and the preliminary design phases of the structural design process is proposed and developed based on the theory of fuzzy sets. The methods developed here are evaluated and compared with similar methods available in the literature. The new method, based on the union of fuzzy sets and contrast intensification, was found suitable for the proposed model. It was implemented as a separate module in the Expert-SEISD. A session with the Expert-SEISD is presented to demonstrate its capabilities of beam and plate designs and knowledge acquisition.
52

A PRACTICAL TOOL FOR THE DETERMINATION OF SURFACE STRESSES IN RAILROAD BEARINGS WITH DIFFERENT CONTACT GEOMETRIES AND LOAD CONDITIONS USING FINITE ELEMENT ANALYSIS

Mason, Michael A 01 January 2014 (has links)
The connection between contact geometry and fatigue in tapered roller bearings utilized in the railroad environment is still of interest. Roller bearings for railroad applications are typically precision ground with crowned contact geometries to prevent edge loading of components. This normally results in completely elastic Hertzian contact stresses under standard railcar loads. However, under extreme load conditions, detrimental edge loading has been known to occur. It is proposed to develop a tool, using finite element analysis, that can be utilized to optimize complex raceway crown geometries for severe applications. A successful implementation of this tool is presented and validated using proven Hertzian contact theory. Correlation within 5% of the ultimate surface and subsurface stress magnitudes, using finite element modeling, in contrast with proven contact theory is achieved. In addition, analyses of other load conditions and contact geometries in order to illustrate the practical application of the tool are exhibited.
53

Nesting Automated Design Modules In An Interconnected Framework

Young, Jared Matthew 21 July 2005 (has links)
This thesis seeks to extend the PDG methodology by developing a generalized formal method for nesting PDGs in an interconnected system. A procedure for decomposing an individual PDG into reusable modules will be defined and a software architecture will be presented which takes advantage of these reusable modules. This method breaks the PDG structure into discrete elements known as PDG objects, PDG modules and PDG services. Each of these elements forms a distinct unit of reuse and each can be seen as a "little" PDG. Two different industrial implementations of this method are presented. These examples show that it is possible to share PDG services amongst multiple PDGs and provide a mechanism to create a PDG for a complicated system.
54

Dust Transportation and Settling within the Mine Ventilation Network

Kumar, Anand 01 January 2019 (has links)
Dust is ubiquitous in underground mine activities. Continuous inhalation of dust could lead to irreversible occupational diseases. Dust particles of size lower than 75.0 µm, also known as float coal dust, can trigger a coal dust explosion following a methane ignition. Ventilation air carries the float coal dust from the point of production to some distance before it’s deposited on the surfaces of underground coal mine. Sources of dust are widely studied, but study of dust transportation has been mainly based on experimental data and simplified models. An understanding of dust transportation in the mine airways is instrumental in the implementation of local dust control strategies. This thesis presents techniques for sampling float coal dust, computational fluid dynamics (CFD) analysis, and mathematical modeling to estimate average dust deposition in an underground coal mine. Dust samples were taken from roof, ribs, and floor at multiple areas along single air splits from longwall and room and pillar mines. Thermogravimetric analysis of these samples showed no conclusive trends in float coal dust deposition rate with location and origin of dust source within the mine network. CFD models were developed using the Lagrangian particle tracking approach to model dust transportation in reduced scale model of mine. Three dimensional CFD analysis showed random deposition pattern of particle on the mine model floor. A pseudo 2D model was generated to approximate the distance dust particles travel when released from a 7 ft. high coal seam. The models showed that lighter particles released in a high airflow field travel farthest. NIOSH developed MFIRE software was adopted to simulate dust transportation in a mine airway analogous to fume migration. The simulations from MFIRE can be calibrated using the dust sampling results to estimate dust transportation in the ventilation network.
55

A Numerical Study in Prediction of Pressure on High-Speed Planing Craft during Slamming Events

Srivastava, Shivank 18 May 2018 (has links)
This thesis is an attempt to create a computer based tool that can be used academically and later industrially by naval architects in analysis and development of efficient planing hull forms. The work contained here is based on the theory created by Vorus (1996) which falls between empirical asymptotic solutions and intractable non-linear boundary value problem in the time-domain. The computer code developed predicts pressures on the bottom of high-speed planing craft during slamming events. The code is validated with available numerical data as a benchmark case. An aluminum wedge is dropped from various heights resulting in unsteady pressure distributions with high peak over the bottom plate. These pressure distributions are compared to the numerically predicted pressures by the code and presented in this thesis. The predicted flow velocities are within 8% difference of experimental data. The graphs depicts similar trends in experimental and numerical data. The predicted peak pressures deviate within 4% to 20% from experimental data. The analysis and comparison illustrate efficacy of the code.
56

Computer modelling of multiple tee-beam bridges

Pircher, Georg, University of Western Sydney, College of Health and Science, School of Engineering January 2006 (has links)
Bridges consisting of multiple parallel pre-stressed and pre-fabricated Tee-beams topped by a cast-on-site concrete slab are often a cost-effective way of constructing simply-supported and multi-span bridge structures in many countries world-wide. For the design of these bridges computer models are often utilised. This thesis presents a comprehensive discussion of modelling issues encountered in the practical design work on this bridge type. A chapter on the modelling of various loading conditions is followed by a detailed discussion of the modelling of the longitudinal load bearing system, the Tee-beams, and the lateral load-bearing system, the roadway slab. A summary of commonly used bridge systems in various countries is also included. All this material is presented considering design code requirements in various internationally used specifications. The information included in this thesis has been used to define specifications for the implementation of a software tool to support the design of so-called Super-Tee bridges. A summary of these specifications is given in the conclusions of this thesis. Material included in this thesis has also been published in the following conference proceedings: Pircher G., Pircher M. (2004) “Computer-aided design and analysis of multiple Tee-beam bridges”, Proceedings: Fifth Austroads Bridge Conference, Hobart, Australia, on CD Pircher M, Pircher G, Wheeler A (2006) “Automated Analysis and Design of Super-Tee Bridges”, Proceedings: Sixth Austroads Bridge Conference, Perth (in publication) / Master of Engineering (Hons)
57

Analysis of Impact Effect to Varied Thickness of Golf Club Head

Wu, Shih-Ping, 26 July 2001 (has links)
ABSTRACT The substance of this study is to analyze the impact process between golf club head and golf ball by integrating the capability of the CAD software I-DEAS and the finite element analysis software LS-DYNA. The various golf club head can be created much easily by determined the dimension parameter in the variable-parameter characteristics of I-DEAS. The computational cost can be reduced by explicit central difference method of LS-DYNA. This study is to analyze the impact effect of varied thickness based on Taguchi method of experimentation and off-center hit in difference volume club head. After that, the hitting area, the sweet spot of club head and influencing factors of impact effect are discussed. It is expected that the findings of the study may provide engineers with some effective method to deal with golf club head design.
58

Implicit solid modeling using interval methods /

Chang, Jen-Chien Jack. January 2000 (has links)
Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 77-80).
59

Possible applications of handheld computers to quantity surveying

Saidi, Kamel 28 August 2008 (has links)
Not available / text
60

A mechatronic approach to develop the concept of a materials handling system for a reconfigurable manufacturing environment.

01 November 2010 (has links)
People are unique and display a variety of preferences with regard to the products that are / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, 2007.

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