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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.
21

Dynamic Modeling and Optimization of Cryogenic Air Separations Units: Design and Operation Strategies / Dynamic Modeling and Optimization of Cryogenic Air Separations Units

Cao, Yanan January 2016 (has links)
Support for this work from Praxair; the McMaster Advanced Control Consortium; and the Natural Sciences and Engineering Research Council of Canada (NSERC), Grant CRDPJ 445717, is gratefully acknowledged. / In the air separation industry, cryogenic distillation is the dominant technology for separating large quantities of air into individual high purity component products. Due to the complexity of the process, in addition to significant energy input, air separation units (ASUs) also have high degrees of material and thermal integration and low process agility. As markets become more competitive and dynamic, especially after electricity market deregulation, ASUs can no longer practice mostly stationary operations, and are in need for design and control strategies to achieve high adaptability. In this study, we address such issues through a dynamic optimization framework. The use of rigorous dynamic models is important for developing economically beneficial designs and operating practices. The first part of this study focuses on the modeling aspect. For the column section of the plant, a full-order stage-wise model and a collocation based reduced order model are proposed. Model size, simulation time and predication accuracy are compared. For the primary heat exchanger, a novel moving boundary model is derived to handle the phase change in such a multi-stream heat exchanger. Simulation results demonstrate the capability of the proposed model in tracking the boundary points of the phase change occurrence, as well as the potential pinch point, along the length of the heat exchanger. The second part of the study addresses the operation aspects of ASUs through conducting dynamic optimization studies with collocation based dynamic models. We first performed a comprehensive analysis for a storage-then-utilization strategy on a nitrogen plant, following a two-tier multi-period formulation. As the parameter varies with time, the plant collects liquid, either directly from liquid product or by liquefaction of overproduced gas product, and then redistributes it for meeting gas product demand or as additional reflux. Effects of electricity price and demand profiles, additional operation costs, as well as product specifications are explored. Then we investigated the economic incentive for employing preemptive actions on a super-staged argon system, which allows the plant to take actions before external changes arrive. In the evaluation, changes are in the gas oxygen product demand. During the preemptive period, the plant takes either a single set or multiple sets of control actions. In the demand increase case, operation degrees of freedom are introduced to or removed from the set of decision variables. The demand decrease scenarios are explored with an under-supplied or saturated liquid oxygen market. / Dissertation / Doctor of Philosophy (PhD)
22

Accepterat pris : En analys av samarbeten inom fastighetsmäklarbranschen och dess prissättning

Billstam, Sofie, Gustafsson, Madeleine January 2012 (has links)
ABSTRACT Title: Level: Author: Supervisor: Date: Aim: Method: Accepted price – An Analysis of Cooperation in the Real Estate Markets and its Pricing. Final assignment for Bachelor Degree in Business Administration Madeleine Gustafsson and Sofie Billstam Jonas Kågström 2012 - May The aim with this final assignment is to investigate if the introduction and the cooperation of accepted price was necessary to generate a more stable real estate market with marketable listing prices in Stockholm. The introduction of accepted price led to a cooperation with some of the most important real estate firms in Stockholm. This cooperation was opposed by a number of companies on the real estate market. This fact inspired to examine similarities and differences of being and not being part of the cooperation and thereafter comment on the outcome. The aim is to compare the pricing between companies within the cooperation of accepted price and external companies and the advantages and disadvantages of entering and not entering a collaboration. The main questions to be answered are: - Is the cooperation necessary to regulate listing prices to a marketable level? - What are the effects of higher listing prices on the Swedish real estate market? - What´s the best possible method when pricing listing price? - What are the advantages and disadvantages of entering and not entering a collaboration? The final assignment has been implemented in an abductive way. The essay is mainly based on secondary data in form of journals, websites, literature and qualitative empirical data collected trough three interviews with Erik Carlborg, Mats Uddare and Fastighetsmäklarnämnden. Quantitative empirical data has been collected trough a questionnaire sent to real estate agents working at Svensk Fastighetsförmedling in Stockholm. Theory and empirical evidence has been analyzed and linked together in the analysis chapter, where the essayists’ thoughts and opinions have been presented. Result & Conclusions: Suggestions for future research: Contribution of the thesis: Key words: The result of the study demonstrates that cooperation between competitors in the same industry in this case is positive since it does not involve a "win-lose situation". How a listing price is set can be affected by numerous factors. To conclude, it is important to keep the price at a marketable level in order to keep the real estate market stable. What the pricing is called is less significant. The pricing should only be called price. The study is delimited to two companies, Svensk Fastighetsförmedling and Karlsson&Uddare, and can therefore not represent the entire real estate market in Stockholm. The study has been limited to brokers at Svensk Fastighetsförmedling in order to compare the brokers’ views with the views of the management within the company. Since the accepted price is relatively new on the Swedish market, there is also a limitation in comparing similarities and differences over time. Suggestions for future research may therefore be to examine how the accepted price has affected the market for a longer period of time, and how the cooperation of accepted price is progressing. A larger study may also be performed where more firms and brokers could be included in order to generalize to the entire industry. This essay contributes whit the brokers’ opinion about the introduction of accepted price, which has not been examined earlier. In addition to this, the essay contributes with an analysis about cooperations and pricing, which are the main parts with accepted price. It also shows the advantages and disadvantages of being and not being part of the cooperation. Accepted price, Listing price, Time on market, competing cooperations, Svensk Fastighetsförmedling, Karlsson & Uddare.
23

On the returns of trend-following trading strategies / Avkastningen från trendföljande handelsstrategier

Lundström, Christian January 2017 (has links)
Paper [I] tests the success rate of trades and the returns of the Opening Range Breakout (ORB) strategy. A trader that trades on the ORB strategy seeks to identify large intraday price movements and trades only when the price moves beyond some predetermined threshold. We present an ORB strategy based on normally distributed returns to identify such days and find that our ORB trading strategy result in significantly higher returns than zero as well as an increased success rate in relation to a fair game. The characteristics of such an approach over conventional statistical tests is that it involves the joint distribution of low, high, open and close over a given time horizon. Paper [II] measures the returns of a popular day trading strategy, the Opening Range Breakout strategy (ORB), across volatility states. We calculate the average daily returns of the ORB strategy for each volatility state of the underlying asset when applied on long time series of crude oil and S&P 500 futures contracts. We find an average difference in returns between the highest and the lowest volatility state of around 200 basis points per day for crude oil, and of around 150 basis points per day for the S&P 500. This finding suggests that the success in day trading can depend to a large extent on the volatility of the underlying asset. Paper [III] performs empirical analysis on short-term and long-term Commodity Trading Advisor (CTA) strategies regarding their exposures to unanticipated risk shocks. Previous research documents that CTA strategies offer diversification opportunities during equity market crisis situations when evaluated as a group, but do not separate between short-term and long-term CTA strategies. When separating between short-term and long-term CTA strategies, this paper finds that only short-term CTA strategies provide a significant, and consistent, exposure to unanticipated risk shocks while long-term CTA strategies do not. For the purpose of diversifying a portfolio during equity market crisis situations, this result suggests that an investor should allocate to short-term CTA strategies rather than to long-term CTA strategies.
24

Undersökning av kostnader som uppstår vid tillverkning av flera produktvarianter : En studie utförd på Axis Communications / Analysis of arising costs related to the manufacturing of multiple product variants : A study performed at Axis Communications

Persson, Jesper, Persson, Johanna January 2017 (has links)
Dagens företag lägger ner allt mer tid och resurser på att utöka variantfloran i deras produktsortiment. Syftet är att nå ut till ett bredare segment av kunder samtidigt som företaget behåller en konkurrenskraftig position på marknaden. Vid framtagning av nya produkter ställs Axis Communications ofta inför utmaningen att ta beslut om att tillverka en eller flera varianter. I dagsläget tas beslut om att tillverka fler varianter i produktsortimentet utifrån priset på direkt material och försäljningsvolymen för varje variant. Axis Communications saknar därmed kunskap om vilka ytterligare faktorer som påverkas när beslut om variantskapande ska tas. Syftet med studien är att ta fram en beräkningsmodell som kan användas som beslutsunderlag vid analys av kostnader i att tillverka mer än en produktvariant. För att besvara syftet har studien genomfört två fallstudier utifrån två olika produkter i Axis Communications produktsortiment. Den första fallstudien analyserar nuläget av tillverkningen hos Axis Communications kontraktstillverkare där kostnader som påverkas av att flera varianter tillverkas identifieras och beräknas. Den andra fallstudien är en fiktivt fallstudie där de identifierade kostnaderna beräknas på nytt men då endast en variant tillverkas och resterande varianter tagits bort. Därefter utfördes en analys på hur de identifierade kostnaderna påverkas vid tillverkning av endast en variant. Utifrån litteraturstudier har de kostnader som påverkas i samband med att flera varianter tillverkas identifierats. Vidare har även processkartläggningar samt ett studiebesök hos en av Axis Communications kontraktstillverkare genomförts där ytterligare relevanta kostnader identifierats och bekräftats av personer med bred kunskap inom området. De kostnader som identifierats i studien och som därmed ansett påverkas mest av att variantfloran förändras är följande: Direkta särkostnader Direkt material Lagerföringskostnader Ställkostnader Fixtur- och verktygskostnader Indirekta särkostnader Kvalitetskostnader Time to Market Investeringskostnader Resurskostnader för utveckling av mekanik Resurskostnader för utvecklig av elektronik Certifieringskostnader Verktygskostnader Kostnader för test av produktion Kostnader för framtagning av prototyper Resultatet för direkt material visade att det går att utgå från ett medelvärde av priset för direkt material samt den prognostiserade försäljningsvolymen per variant för att skapa sig en första uppfattning om hur mycket variantskapande egentligen kostar. Lagerföringskostnaden visade sig också påverkas vid tillverkning av endast en variant. Lagerföringskostnaden minskade i lagret för komponenter men ökade samtidigt i färdigvarulagret eftersom att det endast är den dyrare varianten med avseende på direkt material som tillverkas då det är den variant som har samtliga funktioner jämfört med resterande varianter. Ställkostnaden eliminerades helt då ställtiderna som uppstår vid byte av varianter i tillverkningen försvann. Vidare så halverades kostnaderna för fixturer och verktyg. Kvalitetskostnaden visade sig vara svårare att kvantifiera, dock gick det att inse att desto högre volym som tillverkas av en variant desto fortare når varianten de uppsatta kvalitetsmålen vilket i sin tur bidrar till lägre kvalitetskostnader. Dessutom innebär ett lägre antal varianter i en och samma produktionslina att hanteringen blir lättare då bland annat risken för felmontering minskar. Det blir även lättare att identifiera, prioritera samt åtgärda fel som kan tänkas uppstå i produktionslinan. Det leder i sin tur till att kvalitetskostnaderna minskar. Time to Market påverkades också när endast en variant tillverkades. Även om Time to Market inte direkt kan ses som en kostnad utan snarare som ett intäktsbortfall, påvisade studien att det går fortare att få fram produkterna på marknaden om antalet varianter minskar. Slutligen studerades olika investeringskostnader som går att koppla till tillverkningen av flera varianter och resultatet visade på att det går att minska investeringskostnaderna om endast en variant tillverkas. Utifrån resultatet från de två fallstudierna utformades en beräkningsmodell åt Axis Communications som ska hjälpa företaget med att ta beslut om variantskapande. Beräkningsmodellen lyfter fram de kostnader som påverkas mest av en förändring i variantfloran tillsammans med en beskrivning av hur kostnaderna ska beräknas. Med hjälp av beräkningsmodellen kan Axis Communications beslut om variantskapande underlättas jämfört med hur de tar beslut idag. / Today’s companies spend a significant amount of time and resources on increasing the number of product variants in their product range. The aim is to reach a wider segment of customers while maintaining a competitive position in the market. When developing new products, Axis Communications is often faced with the challenge of deciding whether to focus on one or more product variants. At present, focus is directed towards developing more product variants in the product range based on the price of direct material and the sales volume for each variant. Axis Communications therefore lacks knowledge of what additional factors that are affected when decisions about creating more product variants are taken. The purpose of the study is to provide a calculation model that can be used as a basis for analysing costs in producing more than one product variant. In order to achieve this purpose, the study has carried out two case studies based on two different products in Axis Communications product range. The first case study analyses the current state of production at Axis Communications’ contracted manufacturers, where costs that are affected by the production of multiple variants are identified and calculated. The second case study is a fictitious case study where the identified costs are calculated again, but only when one product variant is manufactured and the remaining product variants are disregarded. This was followed by an analysis regarding how the identified costs are affected when only one product variant is manufactured. Based on literature studies, the costs associated with the production of several variants have been identified. Furthermore, process flow charts have been developed and a study visit to one of Axis Communications contracted manufacturers was undertaken, where additional relevant costs have been identified and confirmed by persons with broad knowledge about the manufacturing processes. The costs identified to be affected the most by the variation of product variants are as follows: Direct incremental costs Direct material Inventory carrying costs Setup costs Fixture- and tooling costs Indirect incremental costs Quality costs Time to Market Investment costs Resource costs for the development of mechanics Resource costs for the development of electronics Certification costs Tooling costs Costs for testing of production Costs for prototyping The result for direct material showed that an average of the price of direct material as well as the forecasted production volume for each product variant can be assumed to create an initial perception of how much an increase of product variants actually costs. The inventory carrying cost also proved affected by the manufacturing of only one product variant. The inventory carrying cost decreased in the inventory of components but increased at the same time in the finished goods inventory since it is only the most expensive product variant with all functions compared to the other product variants that is being stored. The setup cost was eliminated since the setup times that occurred when changing product variants in the production disappeared. Furthermore, the cost of fixtures and tools was halved. The quality cost proved to be harder to quantify, however, it was realized that the higher the volume produced by a product variant the faster the product variant reaches the set quality goals, which in turn contributes to lower quality costs. Additionally, a lower number of product variants in the same production line means that handling becomes easier, including the risk of errors in assembling the product variant. It will also be easier to identify, prioritize and correct errors that may occur in the production line. This in turn leads to a reduction of quality costs. Time to Market was also affected when only one product variant was manufactured. Although Time to Market cannot be seen directly as a cost but rather as a loss of revenue, the study showed that it is faster to launch the product on the market if the number of product variants decreases. Finally, various investment costs were studied that could be linked to the production of several product variants, and the result showed that it is possible to reduce the investment costs if only one product variant is manufactured. Based on the outcome of the two case studies, a calculation model was designed for Axis Communications to help the company decide whether to manufacture product variants or not. The calculation model explains the costs that are affected the most by a change of number of product variants together with a description of how the costs are to be calculated. Using the calculation model will enable Axis Communications to make well-informed decision on whether or not to introduce more product variants in the product range.

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