A turn to more sustainable resources has lead the research during the last decades to algae. Algae is a resource that has been utilized for thousands of years offering a variety of possibilities. Nevertheless modern technology were able to uncover algae’s great potential and pave the way for alternative uses such as biofuel and biomaterial production. Towards that direction, ‘Seafarm’ aims in utilizing algae in the most efficient and sustainable way. For that purpose various steps have been established, including the biorefinery step which entail among other the extraction of carbohydrates from brown algae. The current thesis is based on an extraction of carbohydrates from Saccharina latissima, a brown algae species, which was developed by Viktor Öberg during his master thesis at KTH. The aim of this work is to assist in the scaling up of that laboratory process by analyzing the basic steps and substances of the process, investigating its environmental performance and identifying improvement areas for theoretical optimization. The results of the aforementioned analysis include a substance flow analysis which reveals the basic steps of the process and constitute the basis for further analysis. The second step examines the environmental performance of the process based on the chemical selection. Hence the results are a risk assessment of chemicals with performance indicators for each chemical as well as the whole process. The final part provides a theoretical optimization of the process based on literature studies where the recommendations are divided in production optimization and environmental performance. The above results constitute the basis of the analysis of the process and sets the foundations for scaling up the process at an industrial level. The current analysis in combination with an energy and economic assessment could be used for the designing of the process and its integration in the biorefinery.

Detta examensarbete utfördes på Otis AB, en global tillverkare och underhållare av hissar, rulltrappor och rullband. Arbetet behandlar företagets reservdelshantering och de processer och rutiner som följer av denna. Otis genomförde under hösten 2010 en storskalig kundundersökning som visade att företaget inte lever upp till uppsatta mål rörande kundtillfredsställelse. Företaget har i sin strävan att öka kundernas tillfredställelse insett att en ökning av leveransservicen, den service ett företag kan erbjuda sina kunder vid leverans av varor och tjänster, är nödvändig. Detta är något som företaget tror kan uppnås genom en förändring av den nuvarande reservdelshanteringen. Examensarbetets huvudmål är således att genom att utforma en ny kostnadseffektiv reservdelshantering uppnå en ökning av den leveransservice som Otis kan erbjuda sina kunder. Det underlag som krävdes för utvecklandet av denna rapport har till viss del inhämtats från intervjuer och möten med personer anställda vid Otis Stockholmskontor i Solna. Ett annat viktigt underlag för studien är den statistiska information som gått att inhämta från Otis samt dess huvudsakliga underleverantörer rörande företagets verksamhet. Vidare har utförliga empiriska studier utförts kring de aktiviteter som ingår i företagets nuvarande reservdelshantering. Som ett komplement till dessa studier har passande litteratur använts, litteratur som ligger till grund för både de praktiska och teoretiska studierna. Analysen resulterade i två alternativa logistiska strukturer för företaget. Dessa alternativa logistikstrukturer utvärderades utifrån leveransservice samt kostnadskonsekvenser för att i slutändan kunna jämföras med varandra samt med det nuvarande logistiksystemet. Det ena alternativet består av en intern lagerföring av reservdelar i företagets lagerlokaler i Solna samt Älvsjö medan det andra består av en intern lagerföring av reservdelar i hissmontörernas servicebilar. Av dessa alternativ rekommenderar vi Otis att implementera lagerföring av reservdelar i hissmontörernas servicebilar. Båda de framarbetade logistikalternativen resulterar i en ökning av Otis leveransservicenivå samt i reducerade logistikkostnader jämfört med dagens situation. Båda alternativen har potential att uppnå en liknande leveransservicenivå men där en lägre totalkostnad kan uppnås vid lagerföring i hissmontörernas servicebilar. Detta i kombination med att den övergripande strategin inom organisationen underlättar för en implementering av alternativet med lagerföring av reservdelar i hissmontörernas servicebilar har legat till grund för vår rekommendation. / This thesis was conducted at Otis AB, a global manufacturer and service provider of elevators, escalators and travelators. The thesis deals with the company's spare part handling and the processes and procedures resulting from this. Otis conducted in the autumn of 2010 a large-scale customer survey which showed that the company did not live up to set targets concerning customer satisfaction. The company has in its struggle to increase customer satisfaction realized that an increase in delivery service, the service a company can offer its customers upon delivery of goods and services, is necessary. This is something that the company believes can be achieved by a change in the present spare part handling. The thesis main objective is therefore to design a new cost-effective spare part handling to achieve an increase in the delivery service that Otis can offer its customers. The material required for the development of this report has partially been collected from interviews and meetings with employees at Otis office in Stockholm. Another important basis for the study is the statistical information that has been obtained from the company and its main subcontractors. Moreover, detailed empirical studies have been conducted around the activities involved in the present spare part handling. To complement these studies suitable literature has been used as the basis for both the practical and theoretical studies. The analysis resulted in two alternative logistics structures for the company. These logistics structures were evaluated based on delivery service and cost implications to ultimately be compared with each other and with the existing logistic system. The first alternative consists of internal holding of spare parts in the company's warehouses in Solna and Älvsjö while the second consists of internal holding of spare parts in the elevator mechanics’ service cars. Of these alternatives, we recommend Otis to hold spare parts in the service cars. Both logistics alternatives result in an increase of Otis delivery service and in reduced logistics costs compared to today's situation. The alternatives have the potential to achieve similar delivery service but a lower total cost can be achieved by holding spare parts in the mechanics’ service cars. This fact, combined with an overall strategy of the organization that facilitates an implementation of the alternative consisting of holding spare parts in the mechanics’ service cars have been the basis for our recommendation.

The aim of this thesis is to discuss and analyse the influenceof data uncertainties with regard to the reliability of materialflow analysis (MFA) studies. MFA, as a part of environmentalsystems analysis, is a method belonging to the research field ofindustrial ecology and more specifically industrial metabolism.As such, the method strives at giving a holistic view of thecomplex world we live in, in order to reduce negativeenvironmental impact. Among other things, MFA studies have beenproposed to be useful for priority setting and following up inmunicipalities. Serving as a starting point is a local case study of flows ofnitrogen in a Swedish municipality, Västerås. The casestudy has been performed using the ComBoxmodel. The years studiedare 1995 and 1998. The main sectors in society emitting nitrogento water were identified as the agricultural and householdsectors. The dominating sectors emitting nitrogen to air wereidentified as the agricultural, transport and infrastructuresectors. As a basis for discussing data uncertainties qualitatively andquantitatively a literature survey was performed. 50 articles andbooks were identified as in some way or another dealing with datauncertainties in MFA. The literature survey showed that theuncertainties for results from a MFA study might vary between±30 % and a factor 10 depending on what kind of parameter isinvestigated. Only one method was found that dealt with datauncertainties in MFA in a complete way; a model developed byHedbrant and Sörme (HS model). When applying the HS model to the case study of nitrogen flowsin Västerås, it was found that when uncertaintyintervals were calculated the possible conclusions changed. Ofthe two pair of flows compared in relation to priority setting,none of the earlier conclusions remained. Of the three flowsanalysed in relation to following up, only the flow from onepoint source supported the same conclusion when uncertainty wasconsidered. In all, it is concluded that data uncertainties in MFAanalysis are an important aspect and that further research isneeded in order to improve input data quality estimations andframeworks for determining, calculating and presenting data, datauncertainties and results from MFA studies. However, theunderlying reality remains, e.g. that management of materialflows are important for understanding and reducing the negativeenvironmental impact. Thus, MFA is one useful tool in thiswork. <b>Keywords:</b>data uncertainties, sensitivity analysis,Material flow analysis, MFA, method to determine datauncertainties, case study, ComBox model, nitrogenflows. / NR 20140805

<div>Many two-phase flow systems might undergo flow instabilities even if the system is adiabatic but operates near the saturation conditions, especially in vertical flow conditions. Such instabilities are caused by <i>flashing</i> of the fluid in flow. Flashing is a sudden phase change in the fluid caused when local saturation enthalpy falls below the fluid enthalpy and the excess energy is used as latent heat for gas generation.</div><div> In the current analysis, a mathematical model is presented for analysis of such instability analytically. The conservation equations have been obtained by statistical averaging in time and space. Then, the concerned system is divided into various regions based on flow conditions, and these averaged equations are used to describe the flow. For flashing-based instability, two parameters are derived from constitutive relationships for the fluid. These two parameters are <i>Flashing Boundary</i> and <i>Gas Generation due to Flashing</i>. These parameters provide for the closure of the mathematical model. Some simple models for flashing have been developed and discussed.</div><div> The mathematical model is then solved analytically for <i>Uniform Heat</i> and <i>Flat Model</i> for the heater and flashing region respectively. The solution is in terms of the characteristic equation which is used to predict the onset of instability caused by flashing. The results are then plotted on the Subcooling-Phase Change number plane. It is observed that inlet and outlet restrictions in the flow does <b>not</b> affect the onset of flashing induced instability as the flow rate is coupled with the pressure drop of the system. This is important as these restrictions play a major role in other two-phase flow instabilities such as <i>Density Wave Oscillations</i></div><div> Finally, the stability boundary in the stability plane is compared to experimental data present for flashing. The comparison was made with data of S. Shi, A. Dixit, and F. Inada. The stability boundary satisfactorily agrees with the experimental data thus corroborating the present mathematical model and analysis.</div>

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19986号 / 工博第4230号 / 新制||工||1654(附属図書館) / 33082 / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 酒井 伸一, 教授 米田 稔, 准教授 平井 康宏 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

No description available.

This study has contributed to the developing concepts of circular economy by assessing circular business models and to test different approaches for circularity in a measurable way. In our current era of time, we stand against environment challenges with a warming planet and resources scarcity. To mitigate the effect of greenhouse gasemissions and to find new more circular solutions to material demand. The developing concept of circular economy is aligned with these goals. In this study the climate impact and profitability of circular business models are investigated using material flow analysis. The result is an assessment of these parameters from a sustainability perspective for product organizations and show that longer lifetime and use period a product has the lower the yearly global warming potential. For profitability the assessment is dependent on more parameters such ascurrent business models, gross margin, raw material, logistics and distribution cost an increased profit is not as strongly connected to lifetime or use. When an increasedcircularity can be accomplished as a complement to current business (withoutsignificant cost increase) there is a possible profit.The study suggests an analysis model for investigate circular strategies in theAssessment model for circular business models. The study contributed to the practical adaptation of circular economy principles providing a suggested analysis framework .By applying circular economy principles and this assessment model it is possible to contribute to a more sustainable future for the system of planet Earth. / <p>2023-06-08</p>

The aim of this study is to analyse the voltage regulation of a power grid when wind power parks are connected to an existing power grid. Secondary the project have studied the placement of these wind power parks and costs related to connecting them to the grid. The goal was to achieve this grid with a smaller than 5% voltage margin and preferably a low phase deviation. The power grid is located in the area around Lule älven. Several issues with constructing and connecting windpower parks to an electrical grid have been studied by numerical analysis of a fictive grid but with real world variables. A balanced and stable grid is achieved with wind and hydro power and is able to successfully operate without non-renewable energy sources.The data was simulated in Matlab to analyse the power grid and the modification of it when connecting the wind power parks. The method used is power flow analysis through Matlab. All required unknown voltages and phase angles are determined and whether they are within given specifications. This entails that a stable electrical grid can be constructed

In this competitive world with rapid growth of markets, the main goal of any company is to attain an edge over its competitors. In order to achieve this goal a company has to continually improve its process and eliminate the wastes in the process while not compromising on the quality of the product and customer satisfaction. Though Eco Supplies Solar AB is one of the largest producers of Photovoltaic solar modules in Scandinavia, the need for improvement is vital to match with growing requirements and to maintain its position in the market. This master thesis was done for Eco Supplies Solar AB, so as to help them identify the waste along their value stream process. The project was divided into three phases. The first phase of the project was to map and analyze the plant layout as well as analyze the worker movement. This helped to understand the various movements through the entire process of production and the associated distances and time. The second phase of the thesis was the execution of the Value Stream Mapping. For this purpose the entire production process was walked through and through several interviews the data was collected. The current state value stream map gave a one page static picture of the key areas of waste within the process and to suggest necessary changes so as to improve the efficiency. The suggested changes are implemented and the future state map is drawn. The results from the current state and future state map are calculated theoretically and analyzed. The third phase is the use of Simulation to understand the behavioral effects of each the processes and to determine the overall change in productivity if the changes are implemented. It is difficult to implement changes in a production plant that works continuously for 24 hours. That would interrupt production and also lead to large costs. The easier and most optimal solution to implement changes, understand the behavior of each process before and after the changes and to analyze the changes is to run a simulation model of the current and future state. The simulation is done using Extend Sim software and the results are analyzed further. The main aim of the thesis was to analyze the current plant layout and the product process and develop a methodology to identify visualize and measure the wastes in the production process of Photovoltaic solar modules.

Idag står byggbranschen för 20% av Sveriges konsumtionsbaserade koldioxidutsläpp, och har blivit uppmärksammad i Sveriges strategi för cirkulär ekonomi som en nyckelbransch i omställningen till en cirkulär ekonomi. Detta då byggbranschen till stor del har linjära flöden idag, men det pågår arbete från både myndigheter och branschaktörer för att öka cirkulariteten av dessa flöden. Idag fokuserar dessa åtgärder och studier dock främst på husbyggnation och avfallsminimering. Det finns alltså en kunskapslucka kring cirkularitet för infrastrukturprojekt med ett perspektiv som sträcker sig bortom avfallsminimering och hantering. Genom att kartlägga materialflöden för ett infrastrukturprojekt inom markläggning med en materialflödesanalys och analysera den tillhörande värdekedjan med en SWOT-analys utökar den här studien kunskapen kring cirkularitet för infrastrukturprojekt. Mer specifikt används Skanska och ett av deras infrastrukturprojekt i Stockholm som en fallstudie för att undersöka hur materialanvändningen för Skanska väg och anläggning kan bli cirkulär och öka förståelsen för vilka processer och aktörer som är relevanta för att uppnå detta.  Resultaten visar att viktiga avfallsflöden att minimera för ett cirkulärt projekt är byggpallar, plaströr och brännbart avfall. De visar även att det mesta avfallet inte bildas från byggmaterial utan från emballage. Från materialflödesanalysen är det dock tydligt att överbeställningen av material som idag är mellan 5-10% har potential att utgöra den största orsaken till avfall under andra projektförhållanden. Från SWOT-analysen framkom att samarbete över hela värdekedjan är nödvändigt för att kunna implementera cirkulära lösningar. Styrkor, svagheter, hot och möjligheter för cirkulärt agerande identifierades för alla aktörer och visade bland annat att projektbeställaren är en nyckelaktör för att skapa förutsättningar för en cirkulär materialhantering.  I studien genomfördes även en djupare analys av hur relevanta de i värdekedjan identifierade processer och verktyg är för Skanskas arbete med cirkularitet. Där framkom bland annat att certifieringar som CEEQUAL och Byggvarubedömningen kan vara viktiga utgångspunkter. Det visades även att utformningen av projektet och Skanskas interna hållbarhetsverktyg kan vara nycklar för att skapa förutsättningar, konkreta mål, och arbetssätt för en cirkulär materialhantering. Studien identifierade även en viss diskrepans mellan den gällande avfallslagstiftningen som förespråkar återvinning och den möjlighet och ekonomi som idag finns i materialåtervinning, framför allt för plast. Här kan Skanska och andra byggentreprenörer ha en viktig roll att spela för att skapa efterfrågan på återvunnet material och på så sätt sluta idag linjära flöden. / Today, the construction industry accounts for 20 % of Sweden’s consumption-based carbon emissions, and has been recognized in Sweden’s strategy for the circular economy as a key industry in the transition to a circular economy. One reasoning behind this is the largely linear flows in the construction industry today, but work is underway from both authorities and industry players to increase the circularity of these flows. However, these measures and studies currently focus mainly on house construction and waste minimization. This leaves a knowledge gap for circularity for infrastructure projects with a perspective that extends beyond waste minimization and management. By mapping material flows for an infrastructure project through a material flow analysis and analyzing the associated value chain through a SWOT analysis, this study expands the knowledge about circularity for infrastructure projects. More specifically, a case study of one of Skanska’s infrastructure projects in Stockholm was made to investigate how the use of materials for Skanska can become circular and increase the understanding of which processes and actors are relevant to achieve this.  The results show that important waste flows to minimize for a circular project are construction pallets, plastic pipes and combustible waste. They also show that most waste is not formed from building materials but from packaging. From the material flow analysis, however, the over-ordering of materials that today is between 5-10 % has the potential to be the biggest cause of waste for projects with other conditions than the studied project. The SWOT analysis showed that collaboration across the entire value chain is necessary to be able to implement circular solutions. Strengths, weaknesses, threats and opportunities for circular action were identified for all actors and showed, among other things, that the project client is a key actor in creating the right conditions for circular material handling.  The study also carried out a deeper analysis of how relevant the processes and tools identified in the value chain are for Skanska’s work with circularity. Among other things, it emerged that certifications such as CEEQUAL and Byggvarubedömningen can be important starting points. It was also shown that the design of the project and Skanska’s internal sustainability tools can be keys to create conditions, tangible goals, and strategies for working with circular material handling. The study also identified a certain discrepancy between the current waste legislation that advocates recycling and the opportunity and economy that currently exists in material recycling, especially for plastic. Here, Skanska and other construction contractors can have an important role to play in creating demand for recycled materials and thus increase the circularity of flows.