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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

Improving the packaging of Crosslaminated timber : A master thesis that examines the environment and methods at Martinsons Såg, Bygdsiljum

Berglund, Viktor January 2018 (has links)
This thesis is the final assignment for the program master of science in Industrial Design Engineering at luleå university of technology. The timespan is September of 2017 and early January 2018 and is equivalent to 30 high school credits. The work was performed at Martinsons Såg in Bygdsiljum, Sweden.Martinsons is Sweden’s largest producer of cross-laminated timber, crosslam. The staff is divided into two shifts with nine workers each. The production consists of three sections, gluing, CNC and shipping. The factory was expanded in early 2017 but did not achieve planned output. The last section, the shipping, is a bottleneck. The object of this thesis is to find a layout that solves the bottleneck and improve the working conditions in the shipping, and the pace of the system should be determined by the first process, the pressing. The production starts with the planks. Planks are cut to the right dimensions by a saw and placed in layers. Glue is then applied, and more layers are placed and moved to a press while the glue dries. It results in panels. The maximum size of the panels is 16x3 m. A CNC saw cuts the panels to litteras, custom order parts used to build everything from houses to public areas. The workers pack the littera manually. When the litteras are packed, the packages are loaded on trucks for delivery to the customers. The theoretical background of this thesis consists of three major subjects: industrial design engineering, ergonomic and lean production, with a focus on waste reduction. To understand the system the flows and working procedures were documented with observations, interviews, a survey and some filming. An OWAS were used to observed the ergonomic risks and analyse how they can be avoided. Later in the project were a brainstorming session and workshop used to generate concepts to solve the problems. The concepts were evaluated with a value matrix. The results from the examination of the system showed that the real bottleneck in the system was the crane. It was slow and is also used in the waste flows. Two packaging stations for the litteras cannot be used because of the flow of the sawdust, lowering the capacity and flexibility in the packaging. Summarised, the crane could not deal with the demands from the rest of the system. The ergonomic problems consisted of bent and twisted backs while the workers pack the littera. This thesis proposes an investment plan to solve these problems. It consists of two investments that expand the building and expand conveyors, thus removing much of the lifting much lifting with the crane. The waste and littera flows are separated to allow the crane to focus on the main flow of littera.Two new kinds of packaging stations are implemented to help with the packaging: standard stations that pack the littera on lifts and wall packaging stations that packs littera meant for walls that have many weaknesses. The standard stations consist of scissor lift tables that help reduce the time spent with a bent back while packaging. The temperature is maintained at comfortable levels with an airlock to the outside.
2

Computational analysis and optimisation of the inlet system of a high-performance rally engine

Makgata, Katlego Webster 24 January 2006 (has links)
In the rally car racing there is a need for maximum power throughout the race. While this is not possible through the entire engine speed range, it is possible to manipulate the engine speed at which maximum power is obtained by changing the engine configuration. One of the most effective ways to do this is to modify the intake system to allow for more air into the engine, thus allowing for more fuel to be burnt and more power to be obtained. This dissertation focused on improving the inlet system of a high-performance rally car race engine by using computational fluid dynamics (CFD) and mathematical optimisation techniques, the combination of which is called a computational flow optimisation (CFO) system. Historically, designers have been aware of the importance of proper intake design and with improving technology and a better understating of wave theory, as applied to manifold flow, development moved at fast pace. The application of wave theory to intakes led to a more academic approach to engine tuning, where mathematical relationships were developed to describe the influence of certain engine parameters on air intake. Numerical methods used to solve for flow in intake systems have also developed due to the advances in computer capabilities and are used in the study in the form of CFD and 1-D gas dynamics (as implemented in the engine simulation code used in the study, namely EngMod4T). These are combined with optimisation to arrive at an improved design. The CFD simulations are transient in nature in order to capture the pulse interactions and their influence on the mass of air inducted by the intakes. The first case considered is that of a single intake exposed to atmosphere. To relate the results of the single intake simulation to a full-intake simulation, the mass of inducted air is assumed to be equal for all four intakes. This assumption was found to be flawed as shown by the simulation that followed that took into consideration all four intakes also open to atmosphere. The simulation showed that the intakes actually induct differing amounts of air and the total amount is less than for four single trumpets. A more comprehensive simulation was conducted where the airbox was included and the resulting total mass inducted showed that even less air is inducted by this setup. The results of the latter were used as the basis of the optimisation study that followed. Various airbox designs, obtained from the optimisation software LS-OPT, were simulated and resulted in an improved airbox design that inducts 6.2% more air than the original airbox. And since there is direct relationship between mass of air inducted and engine power produced, it is expected that the engine power would also increase by 6.2%. The study demonstrates the successful implementation of a CFO system to solve a complex industrial flow problem. With the increase of computing power and increasing affordability of such systems coupled with the ease-of-use of commercial CFD software, CFO should become more common in industrial application. / Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2007. / Mechanical and Aeronautical Engineering / unrestricted
3

Optimal Tundish design methodology in a continuous casting process

De Kock, Daniel Johannes 07 October 2005 (has links)
The demand for higher quality steel and higher production rates in the production of steel slabs is ever increasing. These slabs are produced using a continuous casting process. The molten steel flow patterns inside the components of the caster play an important role in the quality of these products. A simple yet effective design method that yields optimum designs is required to design the systems influencing the flow patterns in the caster. The tundish is one of these systems. Traditionally, experimental methods were used in the design of these tundishes, making use of plant trials or water modelling. These methods are both costly and time consuming. More recently, Computational Fluid Dynamics (CFD) has established itself as a viable alternative to reduce the number of experimentation required, resulting in a reduction in the time scales and cost of the design process. Furthermore, CFD provides more insight into the flow process that is not available through experimentation only. The CFD process is usually based on a trial-and-error basis and relies heavily on the insight and experience of the designer to improve designs. Even an experienced designer will only be able to improve the design and does not necessarily guarantee optimum results. In this thesis, a more efficient design methodology is proposed. This methodology involves the combination of a mathematical optimiser with CFD to automate the design process. The methodology is tested on a four different industrial test cases. The first case involves the optimisation of a simple dam-weir configuration of a single strand caster. The position of the dam and weir relative to inlet region is optimised to reduce the dead volume and increase the inclusion removal. The second case involves the optimisation of a pouring box and baffle of a two-strand caster. In this case, the pouring box and baffle geometry is optimised to maximise the minimum residence time at operating level and a typical transition level. The third case deals with the geometry optimisation of an impact pad to reduce the surface turbulence that should result in a reduction in the particle entrainment from the slag layer. The last case continues from the third case where a dam position and height is optimised in conjunction with the optimised impact pad to maximise the inclusion removal on the slag layer. The cases studies show that a mathematical optimiser combined with CFD is a superior alternative compared to traditional design methods, in that it yields optimum designs for a tundish in a continuous casting system. / Thesis (PhD (Mechanical Engineering))--University of Pretoria, 2006. / Mechanical and Aeronautical Engineering / unrestricted
4

Beyond Disruptions: Optimizing Supply Chain Resilience : A qualitative and quantitative analysis of the aftermarket supply chain

Andersson, Sara, Karlsson, Jesper January 2023 (has links)
The world is changing, what has been known to work has been put to the test when both the geopolitical and the environmental climate are changing. War, a pandemic, material shortage, financial difficulties and an overall dis- tressed global transportation sector have shown that the ever-more important topic of resilience is crucial to stay relevant in today’s competitive markets. Companies are therefore switching focus towards ensuring sufficient supply chain resilience capabilities to handle these ever-changing situations on the global market.  In this thesis, we focus on how Volvo SML is working with resilience today, and how graph theory and optimisation can be useful tools when analysing a supply chain’s resilience. We made a qualitative analysis by conducting inter- views with employees and comparing our findings with capabilities related to resilience. In addition, we conducted a quantitative analysis by constructing a simulation of the supply chain, comparing two topology metrics and two op- timisation metrics, to analyse the robustness of the aftermarket supply chain.  We analysed the data and summarised the insights gathered from the inter- views using a resilience capability framework. Volvo SML proved to be agile and reactive when dealing with disruptions but is missing some key capabil- ities during the pre-and post-disruption phases. Some areas of improvement we identified were: robustness, collaboration and redundancy. We proved that the simulation is useful when evaluating the robustness of a supply chain, and we showed that a more flexible way of working would improve the overall robustness of Volvo SML’s aftermarket supply chain.

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