| 51. |
- Risberg, Daniel, 1988-
(författare)
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Analysis of the Thermal Indoor Climate with Computational Fluid Dynamics for Buildings in Sub-arctic Regions
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis aims to increase the knowledge of simulation of thermal indoor climate for nearly zero energy buildings in a sub-arctic climate. Air heating systems in cold climate generate temperature gradients, which negatively affects the thermal indoor climate. Stand-ard multi-zone modeling has problemswithpredicting these gradients.In this work, Computerized Fluid Dynamics (CFD) simulations are used to model the tem-perature gradients. The consequences of reducing the cell sizes for the simulation volume are estimated and case studies of different building and heating systems are presented. The CFD method is validated for a traditional underfloor heating system and also for an air heating system.Furthermore, the effects of snow on heat losses for common building foundations are in-vestigated, and snow is shown to be an important boundary for CFD simulations of a build-ing. The snow and ground freezing areshown to reduce the annual heat losses between 7-10%.The CFD method is shown to be a suitable method for predicting thermal indoor climate. The method can determine the temperature variations inside a building, for different rooms, floors and heating systems. The CFD method is most appropriate for local distributed sys-tems. For traditional hydronic systems the method may be overambitious,since a good indoor climate is usually achieved anyway.Heat transfer coefficients are inaccurate when calculated using standard wall functions used in many turbulence models (like the k-ε model) for surfaces with a high heat transfer rate and natural convection. Automatic wall functions have shown better accuracy for this type of problem, but they require more cells. In order to still use the k-εmodel, a user defined wall function is investigated. This method gave good results and a significant re-duction in the number of necessary cells in the simulation volume. The validation of the indoor climate shows that the wall boundary conditions are important for predicting the indoor temperaturevariations for steady state simulations.New buildings have a higher thermal inertia, which affects the heat losses. It is important to include this effect in the boundary condition calculations for a CFD model.The CFD simulations show that air heatingand local distributed heating systems have dif-ficulties infulfillinga good thermal comfort inside all rooms. This is especially true for rooms with exhaustair and closed doors and multi-storybuildings. Results from a CFD simulation can be used to improve the thermal comfort in these cases.
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| 52. |
- Saari, Juhamatti
(författare)
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Machinery diagnostic techniques for maintenance optimization
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- One of the future challenges of machinery diagnostics and prognosticsis to prepare for the Internet of Things (IoT), where it is possible to change and improve existing approaches drastically. An intensifying application of the IoT will increase the use of embedded sensors and, therefore, create a demand for diagnostic tools where manual workis minimized and is mainly handled by smart algorithms. The auto-mated anomaly detection of large assets and their components with a system of smart algorithms needs proper optimization. Foremost, it is critical to avoid machinery failures, since they can interrupt production, cause unbearable production losses for the business and, even more, can put the lives of personnel in danger if a catastrophic failure occurs. On the other hand, if all the components are repeatedly creating false alarms, the verification of these incidents may be overwhelming. This research studied how a one-class SVM can be optimized by tuning the algorithm to function properly by taking the criticality of the system into consideration. Another topic dealt with was how a one-class SVM can be used for identifying the location of faults by carefully selecting proper input features. Furthermore, a method was tested where a variational Bayesian for Gaussian mixture algorithm was used for pre-processing and separating the condition monitoring data into operation mode classes. Later these classes can be used for improving the time for acquiring the condition monitoring data or to give more information as to how prognostic algorithms should be selected. In addition, a method was tested which involved the use of a Random Forest for feature selection and for the creation of indifference to load or other similar external factors by comparing separate classes with each other. Overall, the idea is that all of these tech-niques can be combined and merged in order to improve machinery diagnostic tools and prepare for the coming era of digitalization
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| 53. |
- Sabau, Cristian, 1989-
(författare)
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FRCM-Composites for Strengthening Concrete Walls with Openings : Experimental and Numerical Analysis
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Upgrading existing buildings to new functional requirements may require new openings that can weaken the structure, prompting the need for strengthening. In such cases, traditional strengthening solutions, such as creating a reinforced concrete or steel frame around the opening, imply long-term restrictions in the use of the structure.In this study, the author carries experimental and numerical investigations on fiber reinforced cementitious matrix (FRCM) composites and their effectiveness for strengthening reinforced concrete walls with openings.To assess the performance of FRCM composite having different fiber types and their suitability for strengthening reinforce concrete walls with openings, single-lap direct shear tests were carried out using carbon, glass, and basalt FRCM-concrete joints. A novel non-contact measurement approach, based on digital image photogrammetry, applied to the experimental study of the bond behavior of FRCM composites was proposed and investigated. The proposed measurement approach showed higher spatial measurement resolution and increased accuracy compared to traditional contact approaches.The effect of cutout openings on the structural behavior of concrete walls was investigated experimentally, by loading to failure, half-scale, precast reinforced concrete panels with and without openings. The tested specimens were two-way action panels to which axial load with a small eccentricity was applied, thus the tested panels were representative of wall panels in buildings. The effect of cutout openings on the global behavior of a building structure was investigated through finite element analysis of an existing building where cutout openings were introduced in wall panels. Depending on their size, cutout openings can significantly decrease the capacity of the wall. The effectiveness of FRCM strengthening to restore the capacity walls with cutout openings was investigated experimentally. FRCM strengthening increased the capacity of walls having small door type openings (opening width was 25% of the wall’s width) to that of the solid wall. The capacity of the walls with large cutout openings was (opening width was 50% of the wall’s width) was increased to 75% of the solid wall’s capacity. The numerical and experimental analysis indicated that the decrease in axial load caused by cutout openings was proportional to the width opening. However, the numerical analysis of buildings structure indicated that the effects of openings on the buildings load carrying capacity are less severe.
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| 54. |
- Sarlus, Zimer, 1984-
(författare)
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Timing and Origin of Igneous Rocks in the Gällivare area, Northern Sweden
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Gällivare area is one of Europe’s top mining regions. The area is located in the northern Norrbotten ore district which hosts ore deposits such as the Malmberget underground iron ore mine, the Aitik open pit Cu-Au mine and the currently explored Nautanen Cu-Au deposit. In addition, several small, mineralized bodies are found. These deposits are hosted by volcanic and volcanosedimentary rocks intruded by intrusive rocks. Previous studies of intrusive and volcanic rocks have often been of local scale and restricted to the major deposits, or of regional scale including entire northern Norrbotten. Minor attention has been paid to rocks of the Gällivare area on a semi-regional scale, especially the intrusive rocks. Very few studies have presented radiometric data of the intrusive and volcanic rocks. In addition, the choice of radiometric method or the re-sults have been lacking confidence. A multidisciplinary approach combining structural geology, geochemistry, geochronology and geophysics is commenced to understand the geological history, crustal geometries and geological evolution of the Gällivare area. This forms basis for future exploration of ore deposits. This study presents geochemical, geochronological and Hf-isotope results with the purpose to characterize and classify major intrusive and volcanic rocks, their timing, source magmas and tectonic environment.Petrographical and geochemical investigations reveal that the intrusive rocks range in composition from ultramafic-mafic to felsic. The ultramafic-mafic rocks comprise dominantly gabbroic layered complexes with peridotitic sequences and have tholeiitic to calc-alkaline affinity. The intermediate and felsic intrusive rocks show calc-alkaline to shoshonitic affinity. Volcanic rocks of the Malmberget deposit show alkali to alkali-calcic character. The geochemical character of the intrusive and volcanic rocks favors a continental arc, transitional to extensional setting (late- to post-collisional).Radiometric in situ U-Pb zircon analyses indicate that mafic and felsic intrusive rocks were generated during magmatic episodes at 1.88, 1.80 Ga and 1.78 Ga. Volcanic rocks hosting the Malmberget deposit belong to the 1.88 Ga magmatic episode. Hydrothermal overgrowth rims from the analyzed zircon crystals indicate extensive reworking and high-T metamorphism of the area around 1.81-1.78 Ga.The mafic-intermediate rocks show minor internal variations in Hf-isotopic signature as well as minor variations inbetween the samples indicative of relatively homogenous source regions beneath the Archean basement. The felsic rocks show a wider range in their Hf-isotopic signature suggesting multiple sources with contribution from old Archean crust.It is here suggested that a subduction process active at 1.9 Ga resulted in a volcanic arc system and ex-tensional environments (back-arc environments) leading to mafic, intermediate and felsic magmatism in the Gällivare area at 1.88 Ga. The mafic-intermediate rocks were extracted from a rather homogenous source reservoir. The c. 1.80 Ga and 1.78 Ga intrusive rocks indicate a complex tectonic evolution of the area at that time. The early 1.80 Ga mafic rocks are suggested to have been generated as a result of extensional magmatism related to an east-directed 1.80 Ga subduction system. Subsequent compression followed by uplift, resulted in the generation of 1.78 Ga felsic rocks.
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| 55. |
- Schmidt, Mischa
(författare)
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EVOX-CPS : A Methodology For Data-Driven Optimization Of Building Operation
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Existing building stock’s energy efficiency must improve due to its significant proportion of the global energy consumption mix. Predictive building control promises to increase the efficiency of buildings during their operational phase and thus lead to a reduction of the lion’s share of buildings’ lifetime energy consumption. Predictive control complements other means to increase performance, such as refurbishments as well as modernization of systems.This thesis contributes EVOX-CPS, a holistic methodology to develop data-driven predictive control for (existing) buildings and deploy the control in day-to-day use. EVOX-CPS evolves buildings into Cyber-Physical Systems and addresses the development of data-driven predictive control using computational methods. The thesis’ focus rests on accounting for the situation of existing buildings - which vary greatly regarding their physical characteristics, usage patterns, system installation, and instrumentation levels. The methodology addresses the aspect of building stock variety with its capability to flexibly adapt to different buildings’ characteristics, e.g., by supporting the integration of varying levels of pre-existing building instrumentation. Furthermore, EVOX-CPS supports using different data mining, regression, or control techniques (i) to strengthen the support for a variety of buildings, and (ii) to cater to researchers’ and practitioners’ differing skills, experiences, or preferences concerning different data analysis techniques. Through its flexibility, the methodology addresses a vast potential installation base and lowers the barriers for adoption in day-to-day use, e.g., by being able to leverage prior investments in building instrumentation and supporting different data-analysis techniques. At the same time, EVOX-CPS provides researchers and practitioners with comprehensive guidance relevant to their daily work. Besides, EVOX-CPS supports addressing a building’s known limitations in the daily operation, e.g., uncomfortable indoor conditions.The experimentation in two real buildings validates the effectiveness of EVOX-CPS’ data-driven control with high reliability due to prolonged experimentation periods combined with applying energy normalization and inferential statistics. The experiments during routine heating system operation establish high confidence in the recorded effect sizes: the improvements in operational efficiency are profound and statistically significant. More specifically, the experiments of controlling the grass heating system of the soccer stadium Commerzbank Arena, Frankfurt, Germany, in two winters saved up to 66% (2014/2015) and 85% (2015/2016) of energy consumption. Extrapolation to an average heating season leads to expected savings of 775 MWh (148 t of CO2 emissions) and 1 GWh (197 t CO2), respectively. The experiments also show that EVOX-CPS allowed alleviating the known operational limitation of heating supply shortages which required nightly preheating in the stadium’s standard operating procedures. In another set of experiments, we applied the methodology to control the heating system of the Sierra Elvira School in Granada, Spain. The experimentation occurred during the regular class hours of 43 school days in winter 2015/2016. A first experiment demonstrated the possibility to lower consumption by one-third while maintaining indoor comfort. Another experiment raised average indoor temperatures by 2K with 5% additional energy consumption. Again, that illustrates EVOX-CPS’ capability to address a building’s known operational issues.
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| 56. |
- Shadram, Farshid, 1987-
(författare)
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Assessment and optimization of life cycle enrgy use in buildings
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Buildings account for 40% of all energy use in European countries. The European Union (EU) therefore encourages member states to adopt Energy Efficiency Measures (EEMs) and implement energy-efficient practices during building design to minimize the energy use of buildings. However, recent studies have shown that energy-efficient buildings may not always outperform conventional buildings in terms of Life Cycle Energy (LCE) use. This is mainly due to the trade-off between embodied and operational energy, and a reliance on EEMs that reduce operational energy while sometimes increasing embodied energy and LCE use. To improve buildings’ environmental performance, the impact of different EEMs on buildings’ energy use needs to be assessed from a lifecycle perspective, and methods for identifying optimal combinations of EEMs that minimize LCE use should be developed. Ideally, these methods should be integrated with building information modelling (BIM) to enable seamless data exchange and to help Architecture, Engineering and Construction (AEC) practitioners make optimal design decisions relating to EEMs. The work presented in this thesis had two overall objectives: (1) to explore the scope for developing BIM-supported method(s) for assessing and optimizing the impact of EEMs on buildings’ LCE use during the design process, and (2) use the BIM-supported method(s) for exploring the impact of various EEMs that are implemented and modified during the building design process on the buildings’ LCE use.The work presented in this thesis is based on an exploratory research design involving iterative cycles of (1) problem identification, (2) method development, (3) method examination, and (4) theory suggestion. In step 1, problems were identified by conducting literature studies and workshops with AEC practitioners, and analyzing archival data. In step 2, prototyping was used to develop methods to overcome the identified problems. In step 3, the applicability of these methods (or prototypes) was tested in case studies on actual and hypothetical building projects. Three case studies were conducted – one dealing with a low energy dwelling located in Kiruna, Sweden; another dealing with a multifamily residential building in Uppsala, Sweden; and a third dealing with a hypothetical multifamily residential building in Stockholm, Sweden. In step 4, the results were compared to existing theories to strengthen existing knowledge and identify previously unrecognized findings.In relation to the first objective, the results obtained show that the factors and activities required to develop BIM-supported method(s) for assessing and optimizing the impact of EEMs on a building’s LCE use during the design phase are:• A database that stores external and building project data (e.g. BIM data) and links it to be used for assessment and optimization, providing access to the data whenever needed.• The development of interfaces using middleware applications to ensure interoperability and seamless automated exchange of information between BIM and other systems.• Predefined objects (i.e. building part and component recipes) that are stored in a database and linked to inventories and Environmental Product Declarations (EPDs) for the relevant materials, enabling assessment of the buildings’ embodied energy and LCE use.• The application of multi-objective optimization techniques (e.g. Pareto-based genetic algorithms) to identify optimal solution(s) for EEMs that minimize (optimize) the building’s LCE use.In relation to the second objective of the thesis, the results obtained indicate that:• EEMs that are implemented and modified during the detailed design phase have much less influence on the building’s LCE use than those implemented in the early design phase. Highly influential EEMs related to the early design phase which were tested herein were the building’s shape, orientation, Window to Wall Ratio (WWR), and the selection of materials used in the building envelope.• Generally, thickening roof insulation has a strong beneficial effect on LCE use for buildings in Sweden.• For buildings using energy sources with high primary energy factors, the most effective way to reduce LCE use may be to implement many EEMs that reduce operational energy use. However, this approach may be less helpful for buildings using greener energy sources because in such cases the embodied energy may have a greater effect on the final LCE use.• The embodied energies of materials in the same class can vary significantly between suppliers. Such differences in embodied energy can be identified by considering the suppliers’ EPDs, the energetic contributions due to their mode of transportation from the site of production, and the distance between the site of production and the construction site.• If the developed optimization approach is used to identify optimal combinations of EEMs in the early design phase, designers can freely choose from a wide range of building shapes without greatly affecting LCE use. However, without early phase optimization, designs that use different building shapes may exhibit significantly different LCE use values.The results provide both theoretical and practical contributions that may be useful to researchers and AEC practitioners seeking to develop BIM-supported design processes and to reduce buildings’ LCE use by adopting appropriate EEMs. The results also show that embodied energy can be a major component of a building’s LCE use if the building’s design relies heavily on EEMs designed solely to reduce operational energy use. Policy makers and governmental bodies are thus advised to update regulations and building codes to reflect the importance of embodied energy so as to minimize the LCE use of new and retrofitting building projects.
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| 57. |
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| 58. |
- Shambilova, Guldarya, 1977-
(författare)
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Some new Hardy-type inequalities on the cone of monotone functions
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This PhD thesis is devoted to the study weighted Hardy-type inequalitieswith quasilinear integral operators on the cone of monotone functions. Thethesis consists of six papers (papers A - F) and an introduction, which givesa brief review of the theory of Hardy-type inequalities and also serves to putthese papers into a more general frame.In papers A, D and E we characterize some weighted Hardy-type inequal-ities on the cone of non-increasing functions. This problem is related to theboundedness of the Hardy-Littlewood maximal operator in weighted LorentzΓ - spaces. In papers D and E the case with integral operators defined byso called Oinarov’s kernels are treated. In all cases necessary and sufficientconditions are derived.In paper B we solve the similar problem for the cone of quasi-concavefunctions (i.e. when the function f satisfy two monotonicity conditions,namely that f (t) is non-decreasing and f(t)t is non-increasing). Such functions are of great importance for interpolation theory, approximation theory and related areas in functional analysis. Also here complete characterizations are given in all cases.Paper C is devoted to characterizing weighted Hardy-type inequalities with supremum operators on the cone of monotone functions. In particular, the study of the case with non-decreasing functions was initiated in this paper.In paper F we focus only on the much less studied problem, namely to characterize Hardy-type inequalities on the cone of non-decreasing functions. A new reduction method is used in a crucial way. Some complete charac-terizations for all studied cases are discussed and proved. The investigations initiated in paper C are here developed to a more general theory, which cov-ers all studied operators. The obtained results are used to derive some new bilinear Hardy-type inequalities.
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| 59. |
- Spegel, Elin, 1982-
(författare)
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Essays on the economic impacts of floods and landslides
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis consists of an introduction and four self-contained papers addressing aspects that are important for how the negative societal effects of natural disasters can be handled, using floods and landslides in the Gothenburg region in Sweden as examples. In paper I the valuation of the benefits of reducing the negative effects of floods, namely, property damage, traffic disturbances and water supply security, were analysed, using a choice experiment. To understand what motivates individuals to contribute towards reducing the negative effects of floods, the impact of individual differences in personality traits were also analysed. Data was collected via a web panel, the final sample consisted of 809 responses. The results showed that individuals’ were willing to pay to reduce the societal costs of floods, and that personality traits helped to explain heterogeneity in preferences. People scoring high on the personality trait including empathic and altruistic characteristics increased the individuals’ probability to support policies aimed at reducing the negative impacts of floods. These results indicate that further investments in flood risk reducing measures should be taken and that public support might increase if policy makers emphasize the welfare gained by society as whole, when designing flood management policies. In paper II the preferences for reducing the negative effects of floods, elicited in paper I, were compared to the preferences of public officials involved in flood risk management. Citizens will have to bear the consequences in the future, of decisions made by governments today. Therefore, it can be argued that decisions should reflect citizens’ preferences. By asking citizens and public officials to respond to identical choice-experiment surveys, it was possible to analyse whether priorities and monetary valuations of the negative effects of floods, namely, property damage, traffic disturbances and water supply security, differed. The overall finding was that public officials and citizens preferences were quite similar, and that both citizens and public officials were willing to pay to reduce the negative effects of floods. The results imply that decisions made within the public sector will likely not differ substantially from citizens’ preferences. In paper III the trade-offs between the distributional aspects and aspects of economic efficiency in in four selected European countries compensation systems for damages caused by floods, namely Sweden, England, France and the Netherlands, were analysed. These countries differ in terms of the level of flood risk, influenced by the physical conditions, as well as in philosophical standpoint of what constitutes a just distribution of compensation following a flood. These aspects has come to affect the costs and benefits of the trade-off between availability and affordability on the one hand and incentives to promote economically efficient behaviour on the other. Finally, in paper IV individuals’ valuation of reducing the negative impacts of landslides, namely, impacts on life, impacts on the environment, impacts on infrastructure, and impacts on important societal services, were analysed, using the choice experiment method. We also evaluated whether individuals valuations were sensitive to the level of risk of landslides. Data was collected via a web panel, the final data sample consisted of 504 responses. We found that reducing the risk of landslides had an overall a positive impact on individuals’ utility. The results also showed that individuals’ valuations were sensitive to risk: individuals’ willingness to contribute financially to policy programs aimed at reducing the risk of landslides increased when the probability of landslides increased.
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| 60. |
- Strömbäck, Ulrica
(författare)
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The second myocardial infarction : A known but different experience
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall aim of this thesis was to explore the second myocardial infarction (MI) and describe experiences of the second myocardial infarction from the perspectives of patients and personnel in cardiac rehabilitation (CR).This thesis includes four studies. Studies using quantitative method (I, II) and qualitative method (III, IV) were performed. Studies I and II were retrospective cohort studies based on data from the Northern Sweden’s MONICA myocardial infarction registry. A paired design was used. Study I included 1017 participants, and the corresponding figure for Study II was 820 participants. The participants had at least two MI events recorded in the MONICA MI registry from 1990 – 2009 (I) and 1986 – 2009 (II). The two MI events studied were the first and second events. Study III included eight patients who suffered two MIs. The data were collected through interviews about the experience of suffering a second MI. In Study IV, personnel working with CR were interviewed about the experience of working with patients suffering from a second MI and data from study III were used for describing the patients expressed needs during CR. Data were analysed by descriptive and analytic statistics (I, II) and by qualitative content analysis (III, IV).Both men and women had higher risk factor burdens when suffering the second MI compared when they suffered the first MI. Women had a higher risk factor burden at both first and second MI compared with men. Women also suffered the second MI with a shorter time interval than men did (I). The most common symptom reported in men and women at both MI events were typical symptoms. In men, 10.6 % reported different types of symptoms at first and second MI, and the corresponding figure for women was 16.2 % (II). The number of patients with a prehospital delay < 2 hours increased at the second MI. Furthermore, the results showed that patients with a prehospital delay ≥ 2 hours at the first MI were more likely to have a prehospital delay ≥ 2 hours at the second MI (II). Suffering a second MI is a known but different event compared to the first MI, it makes afflicted people realise the seriousness and the importance of making lifestyle changes (III). People express they are more affected after having the second MI, both physically and psychologically (III). In the analysis of congruence between the needs patients expressed linked to CR and personnel’s description of how they worked, a theme emerged: “Be seen as a unique person” 2(IV). The patients expressed a need of customised care, and the personnel described that it was important for them to individualise the care given to these patients.Suffering a second MI is experienced as a different and more serious event that the first one. The patients had gained valuable knowledge due to their previous experience and the second MI was a wake-up call for life style changes. A majority of the patients had typical symptoms at both MI events and an increased number of patients had a prehospital delay < 2 hours at the second MI. We suggest that the personnel in CR pay attention to first-time MI patients’ illness representation to enhance the patient’s awareness of the seriousness of the illness and the fact that they suffer from a chronic illness. The care given after an MI, including cardiac rehabilitation should be person-centred to involve the patient as an active participator in the care and were the patient’s resources and needs are in focus.
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