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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.
1

Enabling traceability of design rationale using the concept of product family description (PFD)

Poorkiany, Morteza January 2011 (has links)
This thesis work is based on the previous researches in design automation at Sandvik Coromant. The concept of product family description (PFD) has been introduced to the company to improve documentation of knowledge in engineering design process. Current documentation at the company for engineering design covers mostly the design definition part of the knowledge. PFD is constituted by design definition and completed by design rationale. This kind of documentation improves reusing, revising and expanding the knowledge at the company. On the other side, PFD is an input for design programming and a good engineering design description for a product provides more efficiency in design programming. The project is started by a survey for several principles and applications for knowledge modelling. Product variant master (PVM) and Semantic MediaWiki are selected by the results of the survey. To show the concept of PVM, modelling of a test product is done in product model manager (PMM) software. The main part of the project is setting up product family description (PFD) by capturing design rationale for the test product, implementing in Semantic MediaWiki. Since the design rationale is not documented, it was recorded during several meetings with the designer of the test product. The description is completed by including the argumentations about the rules, figures, dimensions and etc. Also in the project has been tried to improve and revise the description to make it more simple and efficient. Another objective of the project is to show Semantic MediaWiki as a candidate application for modelling knowledge at the company. In this step the applicability and functionality of both PFD and Semantic MediaWiki is seen. In the next stage the project findings and company documentation are evaluated. In this step has been tried to show the pros and cons of the project. The emphasis of the evaluation is on PFD and the alternative application. In the end a conclusion of the whole methods and findings of the project comes with discussion with people who were involved in this work.
2

Design of a modular small-scale PMMA/Air hybrid rocket research engine

von Platen, Gustaf January 2023 (has links)
Rocket propulsion using the hybrid-propellant scheme is a technology that offers much promise in applications where high-performance liquid rocket engines are deemed too complex and solid rocket motors are considered to lack performance or safety. However, despite extensive research, there is still a lack of knowledge in the theoretical aspects of hybrid rocketry, especially in the area of fuel-oxidizer mixing and fuel regression rate. This lack of a good theoretical model makes the implementation of good, practical solutions and mature, well-functioning designs more diffcult. This disadvantages the hybrid rocket engine when compared to liquid rocket engines or solid rocket motors.In this study, a hybrid rocket engine burning polymethyl methacrylate (PMMA) with compressed air has been designed to the point of a preliminary design defnition. PMMA is a transparent material, and this has been utilized to create a transparent-chamber rocket engine where engine processes can be studied with various optical methods withoutinterrupting or disturbing the operation of the engine. The function of hybrid rocket engines, the technological solutions involved in designing working hybrid rocket engines and the constituent parts of hybrid rocket engines have been studied. The nature of the trade-offs between performance and simplicity that occur when designing a rocket engine are also studied, with a focus on maximizing simplicity, safety and minimizing expenses, while still designing an engine that fulfills basic requirements. The results include a design defnition with a preliminary user’s guide, a feasibility study, and a summary of the results of the hybrid rocket performance model that was used to determine appropriate design parameters.

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