| 1. |
- Cruz, Igor, 1986-
(författare)
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Evaluating the utilisation of industrial excess heat from an energy systems perspective
- 2022
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sweden aims to achieve climate neutrality by 2045. The need to immediately reduce greenhouse gas emissions in order to achieve climate targets affects industry directly. The pulp and paper sector is responsible for more than 50% of industrial energy use in Sweden. Increased energy efficiency is expected to contribute significantly to the reduction of primary energy use. The recovery and utilisation of industrial excess heat (IEH) has been identified as an important potential contribution to energy efficiency in industry. Previous research based on top-down studies has estimated the availability of IEH for entire sectors, and bottom-up results for many case studies are available. While top-down studies lack detailed information on the profile of the excess heat available, bottom-up studies have limited coverage. Detailed information about excess heat amounts and temperature levels is required for the assessment of the potential of the various heat recovery technologies that are available. The aim of this thesis is to present, in a series of steps, methods to systematically analyse an industrial process to obtain a detailed profile of the excess heat available under various process conditions, to aggregate results that can be generalised to whole industrial sectors, and to obtain IEH recovery potentials using different technologies. The assessment of the utilisation options for IEH recovery is complemented with an analysis of system aspects that could affect profitability and global greenhouse gas (GHG) emissions. An energy-targeting procedure combined with optimisation has been applied to six case studies of kraft pulp and paper mills in Sweden. This method obtained IEH profiles that were used in a regression analysis to estimate the IEH availability and electricity generation potentials from low and medium temperature IEH using organic Rankine cycles (ORC). A comparison of profitability and global GHG emissions between ORC electricity generation using IEH and small-scale combined heat and electricity (CHP) production is presented for three energy markets.The results show that there is a potential to increase electricity generation from low and medium temperature IEH by 7–9% in the kraft mills in Sweden, depending on the level of process integration considered. The utilisation of low and medium temperature IEH for electricity generation has the potential to reduce global GHG emissions in all the energy-market scenarios considered, but if biomass is considered a limited resource, district heating (DH) deliveries can achieve higher global GHG reductions. ORC electricity generation from low and medium temperature IEH is economically viable and showed overall better profitability and GHG emissions reductions than small-scale CHP using ORCs. The economic feasibility of ORC electricity generation is less affected by external conditions and uncertainties than direct DH deliveries.
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| 2. |
- Jandinger, Magnus
(författare)
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On a Need to Know Basis : A Conceptual and Methodological Framework for Modelling and Analysis of Information Demand in an Enterprise Context
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- While the amount of information, readily available to workers in information- and knowledge intensive business- and industrial contexts, only seem to increase with every day, those workers continue to have difficulties in finding and managing relevant and needed information despite the numerous technical, organisational, and practical approaches promising a remedy to the situation. In this dissertation it is claimed that the main reason for the shortcomings of such approaches are a lack of understanding of the underlying information demand people and organisations have in relation to performing work tasks. Furthermore, it is also argued that while this issue, even with a better understanding of the underlying mechanisms, still would remain a complex problem, it would at least be manageable.To facilitate the development of demand-driven information solutions and organisational change with respect to information demand the dissertation sets out to first provide the empirical and theoretical foundation for a method for modelling and analysing information demand in enterprise contexts and then presents an actual method. As a part of this effort, a conceptual framework for reasoning about information demand is presented together with experiences from a number of empirical cases focusing on both method generation and -validation. A methodological framework is then defined based on principles and ideas grounded in the empirical background and finally a number of method components are introduced in terms of notations, conceptual focus, and procedural approaches for capturing and representation of various aspects of information demand.The dissertation ends with a discussion concerning the validity of the presented method and results in terms of utility, relevance, and applicability with respect to industrial context and needs, as well as possible and planned future improvements and developments of the method.
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| 3. |
- Wetterlund, Elisabeth, 1978-
(författare)
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System studies of forest-based biomass gasification
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Bioenergy will play an important role in reaching the EU targets for renewable energy. Sweden, with abundant forest resources and a well-established forest industry, has a key position regarding modern biomass use. Biomass gasification (BMG) offers several advantages compared to biomass combustion-based processes, the most prominent being the possibility for downstream conversion to motor fuels (biofuels), and the potential for higher electrical efficiency if used for electricity generation in a biomass integrated gasification combined cycle (BIGCC). BMG-based processes in general have a considerable surplus of heat, which facilitates integration with district heating or industrial processes.In this thesis integration of large-scale BMG, for biofuel or electricity production, with other parts of the energy system is analysed. Focus is on forest-based biomass, with the analysis including techno-economic aspects as well as considerations regarding effects on global fossil CO2 emissions. The analysis has been done using two approaches – bottom-up with detailed case studies of BMG integrated with local systems, and top-down with BMG studied on a European scale.The results show that BMG-based biofuel or electricity production can constitute economically interesting alternatives for integration with district heating or pulp and paper production. However, due to uncertainties concerning future energy market conditions and due to the large capital commitment of investment in BMG technology, forceful economic support policies will be needed if BMG is a desired route for the future energy system, unless oil and electricity prices are high enough to provide sufficient incentives for BMG-based biofuel or electricity production. While BMG-based biofuel production could make integration with either district heating or pulp and paper production economically attractive, BIGCC shows considerably more promise if integrated with pulp and paper production than with district heating.Bioenergy use is often considered CO2-neutral, because uptake in growing plants is assumed to fully balance the CO2 released when the biomass is combusted. As one of the alternatives in this thesis, biomass is viewed as limited. This means that increased use of bioenergy in one part of the energy system limits the amount of biomass available for other applications, thus increasing the CO2 emissions for those applications. The results show that when such marginal effects of increased biomass use are acknowledged, the CO2 mitigation potential for BMG-based biofuel production becomes highly uncertain. In fact, most of the BMG-based biofuel cases studied in this thesis would lead to an increase rather than the desired decrease of global CO2 emissions, when considering biomass as limited.
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| 4. |
- Lindkvist, Emma, 1984-
(författare)
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System studies of biogas production : comparisons and performance
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Biogas has the potential to be part of the transition towards a more sustainable energy system. Biogas is a renewable energy source and can play an important role in modern waste management systems. Biogas production can also help recirculate nutrients back to farmland. Besides all this, biogas is a locally produced energy source with the potential to increase global resource efficiency, since it can lead to more value and less waste, as well as decreased negative environmental effects. However, biogas production systems are complex, including different substrates, different applications for biogas and digestate, and different technology solutions for digestion, pre-treatment and for upgrading the raw gas. To increase the development of biogas production systems, knowledge sharing is a key factor. To increase this knowledge sharing, comprehensible analysis and comparisons of biogas production systems are necessary. Thus, studies are needed to verify the resource efficiency of biogas production systems from different perspectives.The aim of this thesis is to perform a systems analysis of biogas production systems and to explore how to analyse and compare biogas production systems. An additional aim is to study biogas production systems from a systems perspective, with a focus on environment, energy and economy. Studying biogas production systems from different system levels, as well as from different approaches, is beneficial because it results in deeper knowledge of biogas systems and greater opportunities to identify synergies.Systems studies of biogas are important, since biogas systems are often complex and integrated with other systems. In this thesis, biogas systems analyses are performed at different levels. In the widest system study, classifications of different biogas plants are analysed and classifications in different European countries are compared, with the prospect of paving the way for a new common classification for biogas plants in Europe. Today, classifications vary between countries, and hence comparisons of plants in different countries are difficult. In the narrowest system study, a new methodology for analysing energy demand at different biogas production plants has been developed. The aim was to develop a methodology that is applicable for all kinds of biogas plants with energy inputs. The methodology describes the process of analysing energy demand and allocating energy to sub-processes and unit processes.Further, an approach for assessing the resource efficiency of different treatment options for organic waste was designed. The approach includes environmental, economic and energy perspectives, and was applied to five different regions with several food manufacturing companies. A study of treatment options for organic waste from a single food company was also conducted. The results showed that biogas production is a resource-efficient way to treat waste from the food industry. The approach enables a wider analysis of biogas systems, and the results from the applications show the complexity of assessing resource efficiency. It is also shown that it is important to understand that the resource efficiency of a system is always in relation to the substituted system.In this thesis, three different approaches to analysing biogas production systems are presented: categorization, resource efficiency analysis and energy demand analysis. These approaches all contribute to the understanding of biogas systems and can help, in different ways, to increase knowledge about biogas systems in the world. If knowledge about different biogas systems can be easily disseminated, more of the unused potential of biogas production may be realized, and hence more fossil fuels can be replaced within the energy system.
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| 5. |
- Ludvigsson, Ann
(författare)
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Samproducerat ledarskap : Hur rektorer och lärare formar ledarskap i skolans vardagsarbete
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Denna avhandling handlar om ledarskapet i skolan. Skolan är en sammansatt verksamhet och i ledarskapet handlar det om att hantera många olika uppgifter på olika nivåer. Samtidigt som skolledare och lärare skall leva upp till samhälleliga förväntningar på skolverksamheten skall de också hantera kulturella villkor inom skolan. I avhandlingen studeras hur ledarskapet formas i och av samspelet mellan skolledare och lärare i vardagsarbetet. En fråga fokuserar på hur skolledare och lärare ser på varandra och hur de influerar och förstår varandra i vardagsarbetet. En annan fråga uppmärksammar vilken betydelse skolsammanhanget har för samspelet.För att belysa samspelet används fallstudier som forskningsstrategi. I studien ingår tre F-6-skolor med förskole-, fritidshems- och grundskoleverksamhet. Det empiriska materialet består av intervjuer och observationer. Teoretiskt har studien en socialkonstruktionistisk utgångspunkt i betydelsen av att skolledarskap ses som ett socialt fenomen. Intresset riktas mot att belysa skolledares och lärares utsagor om hur de förstår varandra och varandras ord och handlingar i det vardagliga arbetet. Resultatet ger anledning att fråga vem som egentligen leder vem. Avhandlingen visar tydligt att ledarskap är något som skolledarna och lärarna oundvikligen formar tillsammans – därav titeln Samproducerat ledarskap. Studien visar hur sociala, kulturella och politiska dimensioner i samspelet influerar skolledarnas och lärarnas agerande och ledarskapet. Konsekvensen blir ett ifrågasättande av den allt populärare bilden av ledaren som med stark hand förväntas styra sin organisation. En förståelse för att skolledarskapet är samproducerat, och att sociala, kulturella och politiska dimensioner har avgörande betydelser för hur det utövas medför en mer realistisk syn på skolledarskapets förutsättningar.
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| 6. |
- Andersson, Mona, 1948-
(författare)
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Botvids väg till rätt vård : Planering av ett interorganisatoriskt vårdkedjeprojekt
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The patient Botvid´s way to right care. The planning process of an inter-organizational care pathway project.A general problem in an elderly patient’s care – and rehabilitation process, which involves different care providers, is that there is no one single staff that is responsible for the whole “production process” i.e. from diagnosis to completed treatment. All too often care providers focus on their own part of the process with insufficient communication with other providers, resulting in low quality of care. Poor co-operation also leads to increased demand for check-ups, unproductive waiting time, duplication of work and other inefficiencies. A solution to these co-ordination problems can be to introduce process orientation (integrated care pathways). A process view requires the concerned staff to look at their own work with other eyes. The process view implies that they need to change focus to what is best from the patient’s point of view.Experiences from earlier reforms, that were centrally initiated and managed, show that the concerned staff (doctors, nurses etc.) had too little influence during the planning and implementation phases. Several official reports therefore call attention to the need for broad participation from all of the different staff categories in organizational development.In this thesis a qualitative case study of the planning process of an inter-organizational project between primary care, hospital treatment and municipality care is presented. The aim of the project was to develop an organization that could support a process view among the care providers. The focus of the thesis is on how the project management acted to shape the necessary conditions for a process view to enable the professional staff to participate, and on the role that the change strategy played in this connection.The results show that the professional staff had an active role in the management of the project. The initiator was a doctor, who managed the project team of 50 care staff together with a project leader. This team had a series of meetings and conferences during ten months. By exchanging ideas and experiences they found solutions to the operative problems that were the starting points for the project. They developed an action plan in consensus, with prioritized activities, which is now to be implemented.
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| 7. |
- Gunnarsson, Marie, 1980-
(författare)
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Lärande i arbetslivets övergångar
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Over the course of the last few decades, work-life has changed and now includes a higher degree of instability and insecurity. This thesis takes this change as its starting point, aiming to understand the ways in which individuals manage involuntary work-life transitions at the workplace, in terms of learning.The study has a longitudinal focus, based on interviews of twelve people who used to work at the same plant. Seven of the interviewees were laid off during the financial crisis of 2008, five of them were not laid off, but continued their employment throughout the crisis. Theoretically, the approach is a combination of a pragmatic learning perspective, through which learning is seen as a kind of problem-solving activity, and a narrative perspective that provides tools with which to view stories as carriers of meaning.The results show that insecurity is accepted by many as a non-negotiable part of work-life. Work-life is in many aspects affected by market globalisation the discourse of employability, where the individual bears the responsibility for their personal work-life. By preparing as best they can to be financially, socially and employability-wise well equipped, the interviewees do what they can to minimize the negative effects of the bad times that are bound to come at some point. Across time, many of the interviewees are moving between different approaches to dealing with the insecurity of work-life. In the process of making meaningful strategic choices, they are involved in learning. Experience and future plans play a role in which choices are made, and thereby also form the route that is constructed by each individual as they navigate between different points in their work-life.The final discussion aims at pointing out the effects an insecure work-life impose on people. People tell stories of acceptance towards the instability of work-life, not because they find work-life satisfying or well-functioning, but because they need to. In order to match the qualifications of an employable individual, they cannot oppose it. In doing so they would automatically define themselves as not so flexible, not so employable. This is a result of learning in work-life transitions.
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| 8. |
- Mårtensson, Maria, 1970-
(författare)
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Drömmar om något bättre : Om managementmodeller, mätningar och människor
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- For several years I have, from a management control perspective, followed the development and application of several popular management models, for example, the knowledge management, balanced scorecard, and intellectual capital models. This thesis, comprising four papers and an extended covering paper, contributes to the management control field by discussing and problematizing management models and how they describe humans by means of measurement.This thesis thus does not emphasize the various possibilities for measurement, but rather how measurement is becoming important and what measurement processes might accomplish. Confidence in measurements is great, and the literature often argues for their importance. Furthermore, there is extensive discussion of what factors should be measured and how they should be measured. However, adages such as ‘What gets measured gets managed’ are rarely discussed or problematized.The dream of better visualizing humans in organizational management models is sometimes expressed in powerful terms, both poetic and dreamlike. If only humans were better visualized, the value-creation process would become more understandable, benefiting everyone and burnishing the image of the good organization. However, it sometimes seems as though this initial dream has become blurred, and measurement per se has tended to overshadow the initial vision. In that case, management models become not just tools, means to attaining the dream, but gradually become ends in themselves.There seems to be a contradiction between the idea of visualizing humans in organizational management models and the results of these models. Paradoxically, these management models are not necessarily making people visible – as was intended; rather, the risk is that they may actually make people less visible, or even invisible. Humans have become bare numbers, and where there is no feedback to ‘flesh and blood’ (i.e., humans), measurements risk losing their purpose. The question remains whether humans are actually made more visible by the measurements used in ‘new’ management models, or whether organizations risk rendering humans invisible and reducing them to objects.
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| 9. |
- Stedt, Lisbeth, 1963-
(författare)
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Samarbete och lärande : Om friktion, uppgifters komplexitet och erfarenhetsutbyten i samarbete
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis highlights collaboration among secondary school teachers as an example of employees' possibilities to learn from each other in collaboration. The purpose of the thesis is to throw light upon how employees shape conditions for cooperation, and the importance these conditions have for their possibilities to exchange experiences and influence each other’s task understanding, i.e., their possibilities to learn from each other through collaboration. The thesis’ theoretical bases are action theory and constructivism. The study uses a case-study approach, and involves a combination of participant observation and interviewing techniques. The starting point was to identify factors that appeared to assist or hinder the exchange of experience. One conclusion is that the division of labour seems to have been central to how conditions are shaped and is the basis for teachers' possibilities for experience-exchange. The combination of a common, physical context, and the friction between the teachers’ actions, seems to promote experience-exchange between teachers and contribute to the possibility to learn from each other. Friction could be seen as the basis for teachers’ need to achieve consensus and coordinate action, since friction is a hindrance. Consequently, friction entails both obstacles and opportunities for coordination and learning. The conditions giving rise to frictions that are overcome seem to be shaped by the way teachers divide the work. Tasks with a high degree of complexity seldom cause friction, which is avoided in these contexts through individual labour. Friction seems to occur and be overcome more frequently during cooperation on easier tasks. Teachers' attempts to collaborate on complex tasks, and simultaneously divide work individually, seem to increase the risk of insurmountable friction arising, from power-related and communication barriers.
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| 10. |
- Broberg Viklund, Sarah, 1983-
(författare)
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System studies of the use of industrial excess heat
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Energy, materials, and by-products, can be exchanged between companies, having positive effects in the form of improved resource efficiency, environmental benefits, and economic gains. One such energy stream that can be exchanged is excess heat, that is, heat generated as a by-product during, for example, industrial production. Excess heat will continue to play an important role in efforts to reduce greenhouse gas (GHG) emissions and improve energy efficiency. Using excess heat is therefore currently emphasized in EU policy as a way to reach EU climate targets.This thesis examines the opportunities of manufacturing industries to use industrial excess heat, and how doing so can positively affect industry, society, and the climate. Since different parts of the energy system are entangled, there is an inherent complexity in studying these systems and introducing excess heat in one part of the energy system may influence other parts of the system. This analysis has accordingly been conducted by combining studies from various perspectives, by applying both quantitative and qualitative methods and covering a broad range of aspects, such as technical possibilities as well as climate, policy, economics, and resource aspects.The results identify several opportunities and benefits accruing from excess heat use. Although excess heat is currently partly used as a thermal resource in district heating in Sweden, this thesis demonstrates that significant untapped excess heat is still available. The mapping conducted in the appended studies identifies excess heat in different energy carriers, mainly low-temperature water. Analysis of excess heat use in different recovery options demonstrated greater output when using excess heat in district heating than electricity production. Optimizing the trade-offs in excess heat used in a district heating network, heat-driven cooling, and electricity production under different energy market conditions while minimizing the system cost, however, indicated that the attractiveness of excess heat in district heating depends on the type of heat production in the system. Viewing excess heat as a low-cost energy source also makes it economically interesting, and creates opportunities to invest in excess heat-recovery solutions. Excess heat is often viewed as CO2 neutral since unused excess heat may be regarded as wasted energy. The GHG mitigation potential of using excess heat, however, was found to be ambiguous. The appended studies demonstrate that using excess heat for electricity production or for applications that reduce the use of electricity reduces GHG emissions. The effects of using excess heat in district heating, on the other hand, depend on the energy market development, for example, the marginal electricity production and marginal use of biomass, and on the type of district heating system replaced. The interviews performed reveal that energy policy does influence excess heat use, being demonstrated both to promote and discourage excess heat use. Beyond national energy policies, internal goals and core values were identified as important for improved energy efficiency and increased excess heat use.
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| 11. |
- Gillberg, Claudia
(författare)
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Transformativa kunskapsprocesser för verksamhetsutveckling : En feministisk aktionsforskningsstudie i förskolan
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Denna avhandling hade två syften. 1. Att i ett organisations-, professions- och pedagogiskt samverkansperspektiv studera några förskollärares möjligheter och hinder för utvecklingen av en genusmedveten pedagogik. 2. Att bedriva kvalita-tiv forskning utifrån antaganden om forskning för social rättvisa, som ett bidrag till metodologiutveckling. Följande frågeställningar belyste dessa syften: Hur skapar förskollärare utrymme för reflektion och kunskapsprocesser över tid; vil-ka individuella och kollektiva handlingar utför förskollärare över tid; vilka bi-drag till verksamhetsutveckling kan en studie av detta slag göra? Med feminis-tisk pragmatism som vetenskapsteoretisk grund tillämpades feministisk aktions-forskning som satte förskollärarnas frågeställningar i centrum. Under tre års tid ägde regelbundna träffar rum för gemensamma reflektioner, utvärderingar och planeringar av pedagogiska handlingar. Enskilda och gruppintervjuer, deltagande observationer samt en stor mängd mejl-, telefon- och brevutbyten kompletterade datainsamlingen. Den analytiska forskningsberättelsen växte fram under åter-koppling till förskollärares handlingar och i ljuset av förskollärares diffusa pro-fessionstillhörighet. Handlingarna tolkades utifrån de i feministisk aktionsforsk-ningsmetodologi inneboende principerna vad, vem och kritiska händelser över tid. Organisations- och professionsteoretiska analyser visade att förskollärarnas handlingar varken erkändes som professionella av den kommunala arbetsgivaren eller föräldrarna. Förskollärarnas behov av professionell erkänsla var stort, men när den uteblev, visade sig det långsiktiga utvecklingsarbetet vara av stort värde, därför att förskollärarna lyckades åstadkomma pedagogiskt sett meningsfulla förändringar, vilket understryker den temporala aspekten av organisatoriska för-ändringar underifrån. Förskollärarnas kollektiva handlingar började rota sig i en gemensam värdegrund. Formen av utvecklingsarbetet - att samarbeta med en al-lierad utifrån - var avgörande för skapandet av utrymme för reflektion och kol-lektiva handlingar. Kollektiva handlingar möjliggjordes i hög utsträckning tack vare enskilda deltagares mod att bryta tystnader om orättvisor i den egna verk-samheten. En slutsats är att det är möjligt att åstadkomma organisatoriska för-ändringar över tid genom en radikal öppenhet för agency. Transformativa kun-skapsprocesser kan åstadkommas om erbjudanden till ett genuint deltagande i ett förändringsarbete lämnas och mottas. Genom en problematisering av termer som handling, deltagande, emancipation, social rättvisa och kunskap gjordes ett me-todologiskt bidrag till feministisk aktionsforskning.
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| 12. |
- Hong, Mei, 1972-
(författare)
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Analysis of Some Methods for Identifying Dynamic Errors-in-variables Systems
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A system where errors or noises are present on both the inputs and the outputs is called an errors-in-variables (EIV) system. EIV systems appear in industrial and agricultural processes, medical sciences, economical systems, biotechnology, as well as in many other areas. Until now, a considerable number of methods for identifying dynamic errors-in-variables systems have been proposed. This thesis studies the statistic properties of different EIV methods and explores the relationships between some of the existing methods. An EIV approach, based on a bias-compensated least squares scheme, is considered in this thesis. Three promising estimators are in focus, namely, Zheng's bias-eliminated least squares (BELS) methods, Frisch scheme methods and extended compensated least squares (ECLS) methods. A simplified form of the BELS equation is first proposed. The new equation will simplify the computation and the theoretical analysis. Next, an important relationship between the BELS, Frisch and ECLS methods is found. The defining non-linear equations used by these three methods are equivalent, providing that the same extended model is used. This means that despite the use of different techniques to solve these equations, the three methods will have the same asymptotic estimation accuracy. Furthermore, the thesis studies the convergence properties of BELS. An alternative BELS algorithm is proposed, which has less of a divergence problem under low SNR situations as compared to the classic BELS methods. Another important problem which is investigated in the thesis is the asymptotic accuracy of the estimates. For the BELS method and a third-order cumulants based method, explicit expressions for the covariance matrices of the parameter estimates are derived. With such expressions available, one may obtain insight into how different user choices in the algorithms influence the accuracy. By using the expressions for the covariance matrices, comparisons of the estimation accuracies are made between three Frisch methods and between the time-domain maximum likelihood method and the sample maximum likelihood method. Finally, identification of errors-in-variables systems with periodic input signals is considered. How to utilize the periodic data and how to design instrumental variables in order to achieve the optimal estimation accuracy are analyzed as well.
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| 13. |
- Mardan, Nawzad, 1965-
(författare)
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Combining simulation and optimization for improved decision support on energy efficiency in industry
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Industrial production systems in general are very complex and there is a need for decision support regarding management of the daily production as well as regarding investments to increase energy efficiency and to decrease environmental effects and overall costs. Simulation of industrial production as well as energy systems optimization may be used in such complex decision-making situations.The simulation tool is most powerful when used for design and analysis of complex production processes. This tool can give very detailed information about how the system operates, for example, information about the disturbances that occur in the system, such as lack of raw materials, blockages or stoppages on a production line. Furthermore, it can also be used to identify bottlenecks to indicate where work in process, material, and information are being delayed.The energy systems optimization tool can provide the company management additional information for the type of investment studied. The tool is able to obtain more basic data for decision-making and thus also additional information for the production-related investment being studied. The use of the energy systems optimization tool as investment decision support when considering strategic investments for an industry with complex interactions between different production units seems greatly needed. If not adopted and used, the industry may face a risk of costly reinvestments.Although these decision-making tools individually give good results, the possibility to use them in combination increases the reliability of the results, enhances the possibility to find optimal solutions, promises improved analyses, and a better basis for decisions in industry. The energy systems optimization tool can be used to find the optimal result and the simulation tool can be used to find out whether the solution from the optimization tool is possible to run at the site.In this thesis, the discrete event simulation and energy systems optimization tools have been combined. Three Swedish industrial case studies are included: The new foundry at Volvo Powertrain in Skövde, Arla Foods dairy in Linköping and the SKF foundry in Katrineholm. Results from these cases show possibilities to decrease energy use and idling, to increase production, to combine existing and new production equipment and to decrease loss of products.For an existing industrial system, it is always preferable to start with the optimization tool reMIND rather than the simulation tool – since it takes less time to build the optimization model and obtain results than it does to build the corresponding simulation modeling. While, for a non-existent system, it is in general a good idea to use both the simulation and the optimization tool reMIND simultaneously, because there are many uncertain data that are difficult to estimate, by using only one of them. An iterative working process may follow where both tools are used.There is a need for future work to further develop structured working processes and to improve the model to e.g. take production related support processes into account. To adapt the results in industries, improve the user friendliness of the tool and the understanding of the underlying modeling developments of the optimization tool reMIND will be necessary.
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| 14. |
- Segerholm, Kristoffer, 1979-
(författare)
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Wood Plastic Composites made from Modified Wood : Aspects on Moisture Sorption, Micromorphology and Durability
- 2007
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Wood plastic composite (WPC) materials have seen a continuous market growth worldwide in the last decade. So-called extruded WPC profiles are today mainly used in outdoor applications, e.g. decking, railing and fencing. In outdoor conditions, moisture sorption in the wood component combined with temperature induced movements of the polymer matrix causes deformations of such composites. On the macroscopic scale this may lead to unacceptable warp, cup and bow of the WPC products, but on a microscopic scale, the movements will cause interfacial cracks between the particles and the matrix, resulting in little or no ability to transfer and re-distribute loads throughout the material. Moisture within the composite will also allow fungi and micro organisms to attack the wood particles. The conceptual idea of this work is to use a chemically modified wood component in WPCs to enhance their long term performance. These chemically modified wood particles exhibit reduced susceptibility to moisture, resulting in better dimensional stability and a higher resistance to biological degradation as compared to that of unmodified wood. The objective of this thesis is to study the effects of using modified wood in WPCs on their moisture sorption behaviour, micromorphology and microbiological durability. The modification methods used were acetylation, heat treatment and furfurylation. Equilibrium moisture content (EMC) and sorption behaviour of WPCs were determined by water vapour sorption experiments. The use of thin sections of the composites enabled EMC to be reached within a comparably short time span. The micromorphology was studied by LV-SEM (low vacuum-scanning electron microscope) using a specially designed sample preparation technique based on UV laser. The biological durability was evaluated by laboratory fungal test methods. The moisture sorption experiments showed lower moisture levels for all the composites when modified wood particles were used. This was also reflected in the micromorphological studies where pronounced wood-plastic interfacial cracks were formed due to moisture movement in the composites with unmodified wood particles. The sample preparation technique by UV laser proved to be a powerful tool for preparing surfaces for micromorphological studies without adding mechanical defects caused by the sample preparation technique itself. Results from the durability test showed that WPCs with modified wood particles are highly resistant to decay by fungi.
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| 15. |
- Sjunnesson, Jan
(författare)
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Erfarenhet och processer : en metod för reflekterande ledarskap
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Experience and Process – a Method for Reflective Management is questioning the increasing focus on processes as being the leading management tool for development of technical systems. A process has its strength in its overall visualization of a company’s operational model. It shows the flow of tasks and their interdependencies, similar to an assembly line in a factory. In such means it describes the foreseen repetitive work that takes place in development projects, but it does not cover the aspects of unforeseen deviations nor the working tasks that cannot be performed without a high degree of skill. A process does not cope with experience, which is a major issue for the success of a development project. Experience is built on three corner stones, the memory from what you have been part of yourself, the memory of other people’s actions, and memories from what you have read in literature and experienced by art. By reflecting on memories from dilemmas you have been through, but from a different viewpoint, you will find new aspects on the events; your experience is nuanced and developed. This is used in a method for reflection, the Dialogue Seminar Method. Memories of difficult events are triggered by the associations given when reading qualified literature from authors like Ingmar Bergman and René Descartes. From the memory fragments, the story of what happened is told in an essay. The work with reading, associating and describing are all different forms of inner reflection. When essays from a group of people are ready, they assemble for a dialogue to share the experiences. A nine months training programme for reflection, Experience Development of Project Managers is using the Dialogue Seminar Method to share experiences among project managers from different development organisations. The participants mature in their management role and are able to use reflection to understand and solve difficult problems. It gives them the needed distance to see the context of actual dilemmas. Big changes put the management skills on test. The Dialogue Seminar Method was used by two consultants as a mean to implement a major process change in a large development company. The idea of the new process was described in a presentation material which was the only information available for first development project. They had to use the presentation material together with their experience. Using the method made it easier for managers and other key persons to connect the new process with their current situation and thereby understand and work in accordance to it. The changes were made by people working together. Process descriptions would have assisted the change, but they would not have made a big difference. A better utilization of experience is a success factor for the development industry. Methods for reflection cannot be replaced by processes.
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