Declarative, object-oriented configuration management systems are widely used, and there is a desire to extend such systems with automated analysis and decision-making. This thesis introduces a new formulation for configuration management problems based on the tools and techniques of constraint programming, which enables automated decision-making. We present ConfSolve, an object-oriented declarative configuration language, in which logical constraints on a system can be specified. Verification, impact analysis, and the generation of valid configurations can then be performed. This is achieved via translation to the MiniZinc constraint programming language, which is in turn solved via the Gecode constraint solver. We formally define the syntax, type system, and semantics of ConfSolve, in order to provide it with a rigorous foundation. Additionally we show that our implementation outperforms previous work, which utilised an SMT solver, while adding new features such as optimisation. We next develop an extension of the ConfSolve language, which facilitates not only one-off configuration tasks, but also subsequent re-configurations in which the previous state of the system is taken into account. In a practical setting one does not wish for a re-configuration to deviate too far from the existing state, unless the benefits are substantial. Re-configuration is of crucial importance if automated configuration systems are to gain industry adoption. We present a novel approach to incorporating state-change into ConfSolve while remaining declarative and providing acceptable performance.

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I takt med en förstärkt global uppvärmning har åtgärdsplaner skrivits om att begränsa temperaturökningen, där många länder är överens om att mängden koldioxidutsläpp måste minska. Lösningen till det anses dels som att gå från en fossilberoende energianvändning till en förnybar. Installering av solceller växer och i Sverige kan 5 – 10 % av elproduktionen förväntas komma från solkraft år 2040. Det kvarstår dock en hel del problematik kring effektförlust till följd av partiell skuggning på solceller. Idag tillverkas solpaneler med inbyggda bypass-dioder som förbättrar elproduktionen vid skugga. Forskning påstår även att skuggningsproblematik kan minskas genom att förändra konfigurationen mellan solcellspaneler. Idag sitter panelerna vanligen ihop i serie- och parallellkopplingar, men det kan finnas energivinster i att byta ut mot tvärkopplingar. Syftet med denna studie har varit att ge beslutsunderlag för investerare av solceller, som planerar att placera dem där det finns risk för att skugga kan uppstå. Målet delades in i två delar. Det fanns en experimentell del som jämförde elproduktion utan och med skugga för två olika typer av systemkonfigurationer där solpanelerna var serie-, respektive tvärkopplade. Det fanns även en simuleringsdel som beräknade producerad elenergi på årsbasis för en solpanel som var placerad intill en skorsten. Utifrån det skapades riktlinjer för hur solpaneler bör placeras för att minimera skuggproblematik av närliggande föremål som riskerar att skugga. Experimenten utfördes utomhus och till det användes 16 monokristallina solmoduler, som först sammankopplades i serie och därefter i tvärkopplingar. Systemen anslöts till en växelriktare som omvandlade från likström till växelström. Först uppmättes producerad eleffekt för systemen, varav en modul utsattes för olika skuggförsök. Därefter separerades en solmodul från anläggningen och samma skuggförsök genomfördes på modulen. Resultaten påvisade att vid solcellssystemen hade en verkningsgrad på 16 % för solinstrålning mellan 400 – 700 W/m2. För intensitet lägre än 400 W/m2 och högre än 700 W/m2 avtog verkningsgraden med 1 – 2 %. Hög solinstrålning inträffar vanligen mitt på dagen och solcellerna har troligen då en högre temperatur, vilket sänker effektiviteten. Experimenten påvisade att ju fler av en solmoduls slingor som skuggan faller på, desto lägre blir den producerade eleffekten. Även mängden skugga som drabbar panelen spelar roll. Det beror på att om skugga enbart faller på en slinga kan de övriga arbeta ostört och får därför en högre maxeffektpunkt (MPP) på IU-kurvan. Vid full skugga på en modul minskade effekten med 7,72 % för det seriekopplade systemet (S), respektive 13,87 % vid tvärkoppling (TCT). Att det tvärkopplade systemet producerar lägre effekt vid skugga beror dels på att kretsen innehåller en högre ström, troligen för hög för vad bypass-dioderna klarar av. Om strömmen i en skuggad modul leds genom dess bypass-dioder utvecklas ingen spänning i modulen. Om systemet innehåller fler parallellkopplade strängar kommer även de oskuggade strängarna att minska sin spänning, då den är identisk över hela systemet. Den tvärkopplade kretsen innehöll två parallellkopplade strängar. Känslighetsanalysen där en solmodul avlägsnades från systemet och skuggades enskilt, redovisade snarlika resultat som för systemen. Att placera skuggobjektet längre ifrån visade sig i några försök ge en högre elproduktion, då det är enbart den direkta strålningen som tas bort. Resultaten från simuleringen uttrycktes i enheten ”skuggprestanda”, som anger hur mycket en solmodul ger skuggad jämfört med vad den hade gett oskuggad. Störst betydelse för resultaten hade skorstenens höjd och hur långt ifrån skorstenen som solpanelen placeras, samt val av väderstreck. Lägst skuggprestanda blev 41 % för en seriekopplad modul. Det för en 2 m hög skorsten som placerades intill solpanelen. Resultaten påvisade att skuggprestandan avtog med en ökad höjd på skorstenen, men för en tillräckligt hög skorsten förändrades inte skuggprestandan. Genom att välja ett avstånd som var tillräckligt långt ifrån skorstenen bidrog skuggan inte lika mycket till minskning av elproduktionen. Ju mer sydligt skorstenen var placerad om panelen krävdes ett längre avstånd. Följande riktlinjer för placering av solceller intill skuggande föremål rekommenderas för att garantera att solcellerna ger minst 95 % av vad de skulle ha gjort oskuggade. För ett skuggande föremål med höjden 0,5 m bör solcellerna placeras 0,3 m ifrån föremålet. För ett skuggobjekts höjd på 2 m bör avståndet vara 2,1 m. / The effects of global warming has lead to a temperature rise in the atmosphere. Many countries have agreed to reduce the greenhouse gas emissions in order to mitigate climate change. The energy production today is highly dependent on fossil fuels and thus one solution to reduce emissions is to use more renewable resources. Solar cells are today growing on the market and in Sweden one can expect that solar energy will represent 5 – 10 % of the electricity production in year 2040. Partial shading is still a problem causing losses in the electricity production for solar cells. To reduce the losses due to shading bypass-diodes are built-in on modules. Further successful method can also be to change the interconnections among moduls in a system. At the time of writing this paper, configurations with series-parallel connections between modules are most commonly used, but during partial shading it has been shown that increasing interconnections can increase the outgoing effect. The purpose of this study was to show guidelines for the investor of solar cells, who plans an installation near objects that will creates shadows on the cells. The target consisted of two parts. First, there was an experimental objective which compared two different system configurations where the solar modules first were connected in series and thereafter in “Total Cross Tied”. The other part of the study considered a theoretical simulation to answer questions as how the energy production during a year was changed for a solar panel by placing it near a chimney. Thereafter it should also state guidelines on how to place the panel around the chimney so that the shading effects are no noticeables. The experiments were done outdoors and the system consisted of sixteen monocrystalline solar panels. First the panels were connected in series (S) and thereafter in “Total Cross Tied” (TCT). The system included also an inverter that changed direct current from the solar panels to alternating current. In the first experiment the electricity produced from the systems was measured, whereof one module was exposed to different types of shading. As a final experiment, one module was separated from the system where is was exposed to the same shading pattern as before. The results showed that the PV systems had an efficiency of 16 % for an irradiance between 400 – 700 W/m2. For lower irradiances than 400 W/m2 and higher than 700 /m2 the systems experienced a decreasing efficiency of about 1 – 2 %. A high irradiance occurs normally during the middle of the day when the solar cells have a higher temperature, which decreases the efficiency. The experiments proved that shading more cells so that current will flow through more bypass diodes resulted in a lower electricity production. For example if only one bypass diode is activated it means that the remaining cells that are not connected to that bypass diode can work freely and gets a higher maximum power point (MPP) on the IU characteristics. When a module got completely shaded it reduced the electricity output power with 7,72 % for the system with series connected modules. For the TCT-configuration the system experienced a reduction of 13,87 %. These results may be a contradiction according to previously research. A conceivable explanation is that the TCT-configuration produces higher current, which can exceed the allowed value for a functionally bypass diode. If the current in a shaded module flows through its bypass diodes it results in a short-circuit of the module so that it cannot contribute to the voltage. The more parallel PV arrays a system includes, a higher effect loss will occur since the unshaded strings may experience an identical voltage drop as the shaded one. The TCT-configuration included two strings connected in parallel. The sensitivity analysis where one module was separated from the whole system showed nearly the same results as for the whole system. Placing the shading object far away from the module resulted in a higher electricity production for some tests, as it is only the direct radiation that disappears. The simulations results were expressed in terms of “shading performance” and it showed how much a shaded solar module produced compared to an unshaded. It was shown that the parameters that had the biggest influence on the results were the height of the chimney and how far the solar module was placed with respect to the chimney. As a worst-case scenario, the shading performance was 41 % for a series-connected module. This was for a chimney with 2 m of height that placed next to the solar module. The results indicated that having a higher chimney had a decreasing effect of the shading performance for the solar module. To get a higher shading performance one can choose to place the solar cells at a larger distance from the chimney. Conclusively, placing the solar module so that the chimney is located to the south of the module the shadow will affect the panel more, and a longer distance is therefore needed. If the solar cells are located on a distance that is at least 0,3 m from a shading object with a height of 0,5 m, it means that the solar cells will produce 95 % of what that would have given unshaded. For a shading object with a height of 2 m it means that the solar cells must be placed at a distance of 2,1 m from the object.

The HVAC system configuration is a conceptual design of the HVAC system, including the employed components, the topology of the airflow network, and the control strategy with set points. Selection of HVAC system configuration is normally done in the early stage of the design process. The configuration design, however, has significant impacts on the performance of the final system. This thesis describes the development of the design synthesis of optimal HVAC system configurations by Evolutionary Algorithm. In this research, the HVAC system configuration design synthesis has been formulated as an optimisation problem, in which, the component set of the configuration, the topology of the airflow network, and the control set points for the assumed supervisory control strategy, are the optimisation variables. Psychrometrics-based configuration model has been developed in order to evaluate the optimisation objective of minimising the annual energy consumption of the HVAC system. The optimisation is also subjected to a number of design constraints, including the connectivity of the topology, the performance limitations of the components, and the design requirements for the air-conditioned zones. The configuration synthesis problem is a multi-level optimisation problem. The topology depends on the set of selected components, whereas the search space of the control set points changes with the different components and topology. On the other hand, the performance of the configuration is assessed with its optimum operation; therefore the control set points have to be optimised for each configuration solution, before the optimum configuration can be identified. In this research, a simultaneous evolutionary approach has been developed. All optimisation variables of the configuration have been enwded into an integrated genotypic data structure. Evolutionary operators have also been developed to search the topological space (for the optimum topology) and parametric space (for the optimal control set points) at the same time. The performance of the developed approach has been validated with example optimisation problems. It is concluded that the implemented evolutionary algorithm has been able to find (near) optimum solutions for various design problems, though multiple trials may be required. The limitations of this approach and the direction of future development have been discussed.

Yes / To identify a subset of software issues occurring in daily Swedish healthcare practice and devise a set of local solutions to overcome the challenges. Methods: A sample of 46 incident reports was collected from one of Sweden's national incident reporting repositories, ranging from June 2019 to December 2021. The reports were first subjected to an algorithm to identify if they were health information technology-related incidents and were analysed using an existing framework, i.e., the Health Information Technology Classification System, to identify the software-related incidents. The incidents associated with software issues were then subjected to thematic analysis, in which themes were extracted and presented under the category assigned by the existing framework used. Results: Of 46 reports, 45 (with one exception) were included using the algorithm. Of 45 incidents, 31 software-related incidents were identified using the classification system. Six types of software issues were identified, including software functionality (n = 10), interface with other software systems or components (n = 10), system configuration (n = 7), interface with devices (n = 2), record migration (n = 1) and increased volume of transactions (n = 1). Each issue was further categorised into different themes; for example, software interface-related problems were grouped into ‘two patients being active in the system simultaneously’ (n = 6) and ‘transfer of patient information’ (n = 4). Conclusions: The study provided some insights into software issues and relevant consequences. A set of local solutions were devised to overcome the present challenges encountered in Swedish healthcare in their daily clinical practice. Systematic identification and characterisation of such software challenges should be a routine part of clinical practice for all major health information technology implementations. / This work has been part of being an Affiliated Researcher at the Department of Medicine and Optometry, Linnaeus University, Sweden. A publishing grant was received from Linnaeus University as a part of the University Library's research support.

As part of efforts to curb the protracted electricity problem in Nigeria, the government enacted the National Renewable Energy and Energy Efficiency Policy (NREEEP) in 2014. Through this policy, the country plans to increase its electricity generation from renewables to 20% by 2030. This thesis investigates the economic feasibility of this lofty goal, and as well determine the best hybrid configuration for off-grid rural/remote power generation across the six geopolitical zones of Nigeria The economic feasibility results, using Long-range Energy Alternative Planning (LEAP) tool, show that the 20% renewables goal in the Nigerian power generation mix by 2030 is economically feasible but will require vast investment, appropriate supportive mechanisms, both fiscal and non-fiscal (especially for solar PV) and unalloyed commitment on the part of the government. Moreover, the techno-economic results with Hybrid Optimization Model for Electric Renewable (HOMER) reveal Small hydro/Solar PV/Diesel generator/Battery design as the most cost-effective combination for power supply in remote/rural areas of Nigeria. Findings also highlight the better performance of this system in terms of fuel consumption and GHGs emission reduction. Lastly, the study identifies factors influencing RE development, and offers strategic and policy suggestions to advance RE deployment in Nigeria.

The objectives of this doctoral thesis are to give a basisincluding methods for the development of stationary polymerelectrolyte fuel cell (PEFC) systems for combined heat andpower production. Moreover, the objectives include identifyingprerequisites, requirements and possibilities for PEFC systemsproducing heat and power for buildings in Sweden. The PEFCsystem is still in a pre-commercial state, but low emissionlevels, fast dynamics and high efficiencies are promisingcharacteristics. A thermodynamic model to simulate stationary PEFC systemshas been constructed and pinch technology and exergy analysesare utilised to design and evaluate the system. The finalsystem configuration implies a high total efficiency ofapproximately 98 % (LHV). A flexible test facility was built in connection with theresearch project to experimentally evaluate small-scalestationary PEFC systems at KTH. The research PEFC system hasextensive measurement equipment, a rigorous control system andallows fuel cell systems from approximately 0.2 to 4 kWel insize to be tested. The simulation models of the fuel processorand the fuel cell stack are verified with experimental datataken from the test facility. The initial evaluation andsimulation of the first residential installation of a PEFCsystem in Sweden is also reported. This PEFC system, fuelled bybiogas and hydrogen, is installed in an energy system alsoincluding a photovoltaic array, an electrolyser and hydrogenstorage. Technical aspects of designing a fuel cell system-basedenergy system, including storages and grid connections, whichprovides heat and power to a building are presented in thisthesis. As a basis for the technical and economic evaluations,exemplifying energy systems are constructed and simulated. Fuelcell system installations are predicted to be economicallyunviable for probable near-term conditions in Sweden. The mainfactor in the economic evaluations is the fuel price. However,fuel cell system installations are shown to have a higher fuelutilisation than the conventional method of energy supply. The methods presented in this thesis serve as a collectedbasis for continued research and development in the area. Keywords:Small-scale, stationary, fuel cell system,polymer electrolyte fuel cell, PEFC system, reformer,thermodynamic modelling, pinch technology, exergy analyses,system configuration, test facility, experiments, application,simulation, installation, energy system, energy storage, heatand power demand.

<p>The objectives of this doctoral thesis are to give a basisincluding methods for the development of stationary polymerelectrolyte fuel cell (PEFC) systems for combined heat andpower production. Moreover, the objectives include identifyingprerequisites, requirements and possibilities for PEFC systemsproducing heat and power for buildings in Sweden. The PEFCsystem is still in a pre-commercial state, but low emissionlevels, fast dynamics and high efficiencies are promisingcharacteristics.</p><p>A thermodynamic model to simulate stationary PEFC systemshas been constructed and pinch technology and exergy analysesare utilised to design and evaluate the system. The finalsystem configuration implies a high total efficiency ofapproximately 98 % (LHV).</p><p>A flexible test facility was built in connection with theresearch project to experimentally evaluate small-scalestationary PEFC systems at KTH. The research PEFC system hasextensive measurement equipment, a rigorous control system andallows fuel cell systems from approximately 0.2 to 4 kWel insize to be tested. The simulation models of the fuel processorand the fuel cell stack are verified with experimental datataken from the test facility. The initial evaluation andsimulation of the first residential installation of a PEFCsystem in Sweden is also reported. This PEFC system, fuelled bybiogas and hydrogen, is installed in an energy system alsoincluding a photovoltaic array, an electrolyser and hydrogenstorage.</p><p>Technical aspects of designing a fuel cell system-basedenergy system, including storages and grid connections, whichprovides heat and power to a building are presented in thisthesis. As a basis for the technical and economic evaluations,exemplifying energy systems are constructed and simulated. Fuelcell system installations are predicted to be economicallyunviable for probable near-term conditions in Sweden. The mainfactor in the economic evaluations is the fuel price. However,fuel cell system installations are shown to have a higher fuelutilisation than the conventional method of energy supply.</p><p>The methods presented in this thesis serve as a collectedbasis for continued research and development in the area.</p><p><b>Keywords:</b>Small-scale, stationary, fuel cell system,polymer electrolyte fuel cell, PEFC system, reformer,thermodynamic modelling, pinch technology, exergy analyses,system configuration, test facility, experiments, application,simulation, installation, energy system, energy storage, heatand power demand.</p>

Due to the changes and improvements that have occurred over the years, the manufacturing sector has evolved. Companies in the 21st-century face changes in the marketplace that are difficult to predict due to international competition and the rapid emergence of new products. To cope, companies must reinvent themselves and design manufacturing systems that seek to produce quality and low-cost products, and respond to the changes that must be faced. These capabilities are encompassed in reconfigurable manufacturing systems (RMS), capable of dealing with uncertainties quickly and economically. On the other hand, production planning with this type of system presents a significant challenge. Although simulation-based optimization techniques have been applied to address certain RMS challenges, only a few studies have applied simulation-based multi-objective optimization to simultaneously address several conflicting design objectives, as is the case in this project. This project aims to investigate some aspects using SBMO that directly affect the performance of a plant and demonstrate the usefulness of the method. / <p>Det finns övrigt digitalt material (t.ex. film-, bild- eller ljudfiler) eller modeller/artefakter tillhörande examensarbetet som ska skickas till arkivet.</p>

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