154 research outputs found
Data for "Improved dynamic imaging of multiphase flow by constrained tomographic reconstruction” - simulation_attenuation_rotated
No full textGround truth used for comparison with the reconstructions calculated by the the
algorithms described in the article 'Improved dynamic imaging of
multiphase flow by constrained tomographic reconstruction'. The code can be found at https://gitlab.gbar.dtu.dk/pwra/NumericalExperimentsThis item is a part of the collection: Data for "Improved dynamic imaging of multiphase flow by constrained tomographic reconstruction”, https://doi.org/10.11583/DTU.c.5448594</p
Tomographic Imaging of Flow Processes
No full textX-ray computed tomography (CT) is a powerful metrology that allows for nondestructive imaging of the internal structure of objects. Improvements in X-ray sources, X-ray detectors and increasing computation power have paved the way for dynamic tomography, which enables a new range of experiments. Dynamic experiments are ubiquitous in research fields such as carbon storage, geothermal energy, multiphase flow, rock deformation and research related to the oil and gas industry. The dynamic nature of the experiments constrains the imaging process in that the imaging has to be sufficiently fast to capture it. This constraint can drastically compromise the image quality of tomographic reconstructions if either exposure time or the number of projections is reduced to accommodate the pace of the dynamic experiment. In this thesis, we have developed novel reconstruction algorithms for dynamic experiments to provide high-quality reconstructions despite substandard data. We designed the algorithms for experiments that allow for a high-quality scan of the experiment before any dynamics take place. All algorithms we developed are based on the Simultaneous Iterative Reconstruction Technique, and the best performing of these algorithms had two additions, which improved it. The first addition is we initialise a reconstruction for a given time step with a reconstruction of the previous time step. The first time step is initialised with a high-quality reconstruction of the static system. The second addition is that each pixel in the dynamic reconstructions is constrained such they can only take a single value or a range of values. This constraint is derived from a segmentation of the high-quality reconstruction. We tested the algorithms with simulated data of differing quality to gauge their performance under different conditions. We showed that this algorithm performs far better than conventional methods and allows for a substantial reduction in imaging time. We also examined multiple stopping rules for reconstruction algorithms that estimate the optimal point to terminate a reconstruction. Terminating a reconstruction before or after the optimal point will either result in a blurry or noisy reconstruction. All tested methods provided accurate estimates of the optimal stopping point for data with a moderate or small signal to noise ratio (SNR). Two of the methods do not require any knowledge of the noise level in the data, which makes them very practical. Finally, we performed a dynamic CT experiment to study the scaling formation process. We injected a carbon steel flow cell with water supersaturated with BaSO4 for over 150 hours while imaging it with a CT scanner. We used a modified version of one of the reconstructions algorithms we developed to reconstruct the dynamic data to improve the SNR of the reconstructions. Quantitative analysis of the reconstruction allowed us to gain new insights into the scaling formation process. From this analysis, we show that scaling formation has three distinct growth phases. This thesis and the contributions within it shows the applicability of dynamic tomography for a wide range of fields and how it provides novel insight within these fields
Data for "Improved dynamic imaging of multiphase flow by constrained tomographic reconstruction” - simulation_attenuation_blur
No full textGround truth used for forward projection in the article 'Improved dynamic imaging of
multiphase flow by constrained tomographic reconstruction'. The forward projections can be reconstructed and compared to with the file simulation_attenuation_rotated.npy https://doi.org/10.11583/DTU.14553741 to check the quality of the reconstruction. The code can be found at https://gitlab.gbar.dtu.dk/pwra/NumericalExperimentsThis item is a part of the collection: Data for "Improved dynamic imaging of multiphase flow by constrained tomographic reconstruction”, https://doi.org/10.11583/DTU.c.5448594</p
Data for "Improved dynamic imaging of multiphase flow by constrained tomographic reconstruction” - ground_truth_distribution_time
No full textHistogram of the ground truth as a function of time. This is needed for comparison when evaluating the performance of the algorithms described in the article 'Improved dynamic imaging of multiphase flow by constrained tomographic reconstruction'.The code can be found at https://gitlab.gbar.dtu.dk/pwra/NumericalExperimentsThis item is a part of the collection: Data for "Improved dynamic imaging of multiphase flow by constrained tomographic reconstruction”, https://doi.org/10.11583/DTU.c.5448594<br
Data for "Improved dynamic imaging of multiphase flow by constrained tomographic reconstruction” - ground_truth_distribution
No full textHistogram of the ground truth. This is needed for comparison when evaluating the performance of the
algorithms described in the article 'Improved dynamic imaging of
multiphase flow by constrained tomographic reconstruction'. The code can be found at https://gitlab.gbar.dtu.dk/pwra/NumericalExperimentsThis item is a part of the collection: Data for "Improved dynamic imaging of multiphase flow by constrained tomographic reconstruction”, https://doi.org/10.11583/DTU.c.5448594</p
Vertex Detector Performance for CLICdet, FCCee & FCChh.
No full textThe performance of the vertex detectors planned for CLICdet, FCCee & FCChh was tested in this project. This was done my studying the figure of merit for a vertex detector which is the transverse impact parameter resolution . This was carried out by simulating single at different energies, polar angles, with a uniform distribution in the azimuthal angle . The events were reconstructed and the distribution was fitted with a Gaussian function where the width of the function resulted in . The effect of material budget and fit function on this was also tested
The Global Organic Food Market and Transformation: Deductive Definition of Empiric Indicators, The Demand Explanation, The Institutional Explanation & Comparative Country Report: Denmark versus Sweden:Research Report no. 2
No full textThe present study is part of the project “Public Policies and Demand for Organic Food: An International Comparison of Policy Effects and Policy Determinants” (COP). It is carried out in WP II that concerns the supply-side policies and demand. In the WP it has been an initial task to formulate a theoretical approach as the conceptual framework to be used in comparative studies. The present study represents the first contribution to apply the conceptual framework in an empirical context and here it is the evolution of the organic sectors in Denmark and Sweden that are compared. The study is searching for indicators to explain which factors can explain increase in organic foods production and consumption. It reaches the conclusion that the picture concerning the demand side is very blurred and that it is impossible to reveal which elements are crucial. However, the study also concludes that institutional design and set up seem to be rather crucial for the evolution of the organic sector. I wish to thank Lennart Larsson and especially Peter Einarsson from the Swedish organisation for organic farmers, Ekologiska Lantbrukarna, for their willingness to provide the project with insights. However, the responsible for the research report is the author. The report is written by Ole Horn Rasmussen that for four month has been attached to the WP as research assistant. Aalborg in December 2007-12-21, Jan Holm Ingemann, head of WP II</p
Failures and Defects in the Execution Phase
No full textThis Master Thesis is made by Ilzan Alilovic, who is studying Civil Engineering – Management in the Building Industry, at Aalborg University. The Thesis is named “Failures and Defects in the Danish Building Industry”, and it deals with the failures and defects that are showing in the execution phase of a building process.The Master Thesis consists of 5 main parts. The first part is a description of the Danish Building Industry. In this part the economic benefits of having such a strong Industry in the Danish society are described.The next part consists of multiple definitions upon the terms “failure” and “defect”, and how they are viewed upon in the Danish Building Industry. The third part are then a description of the current situation according to failures and defects in the Danish Building Industry. Multiple reliable sources are used to find out exactly how the current situation is. Based on the research of this topic, it can be concluded that Denmark as a country has never had so many failures and defects in their buildings as they do nowadays. This led to the projects problem statement which is: “What are the main reason/-s that the number of defects and failures in the Danish society are so high today?”This question has tried to be answered, by analyzing 5 different points, which the author believed had the most to do with the problem statement. These 5 points are:1) Subcontractors2) Quality assurance3) Schedule Plans4) Building owner and users5) Poor project materialAt the end of this Master Theses it was further discussed how to reduce the number of defects and failures in the Danish Building Industry. Simple steps were thought of and commented upon. These steps are not there to eliminate failures and defects in the building industry completely but should more likely be viewed as a steppingstone into a future with less defects and better-quality buildings. After the discussion a part was written on ideas how to do further studies, with this topic. The author recommended that one can try to look further from the execution phase, for example the project phase. Another recommendation was that one could try to be assigned to a specific building project. Here it would be possible to go around and note down the number of defects and failures, and after that data could be extracted and used to further make more in-depth going analysis on the issue.This Master Thesis is made by Ilzan Alilovic, who is studying Civil Engineering – Management in the Building Industry, at Aalborg University. The Thesis is named “Failures and Defects in the Danish Building Industry”, and it deals with the failures and defects that are showing in the execution phase of a building process.The Master Thesis consists of 5 main parts. The first part is a description of the Danish Building Industry. In this part the economic benefits of having such a strong Industry in the Danish society are described.The next part consists of multiple definitions upon the terms “failure” and “defect”, and how they are viewed upon in the Danish Building Industry. The third part are then a description of the current situation according to failures and defects in the Danish Building Industry. Multiple reliable sources are used to find out exactly how the current situation is. Based on the research of this topic, it can be concluded that Denmark as a country has never had so many failures and defects in their buildings as they do nowadays. This led to the projects problem statement which is: “What are the main reason/-s that the number of defects and failures in the Danish society are so high today?”This question has tried to be answered, by analyzing 5 different points, which the author believed had the most to do with the problem statement. These 5 points are:1) Subcontractors2) Quality assurance3) Schedule Plans4) Building owner and users5) Poor project materialAt the end of this Master Theses it was further discussed how to reduce the number of defects and failures in the Danish Building Industry. Simple steps were thought of and commented upon. These steps are not there to eliminate failures and defects in the building industry completely but should more likely be viewed as a steppingstone into a future with less defects and better-quality buildings. After the discussion a part was written on ideas how to do further studies, with this topic. The author recommended that one can try to look further from the execution phase, for example the project phase. Another recommendation was that one could try to be assigned to a specific building project. Here it would be possible to go around and note down the number of defects and failures, and after that data could be extracted and used to further make more in-depth going analysis on the issue
Cultural definitions of emotional problems: impact on problem experience, care seeking, sources of care, and satisfaction with care among Latino community members living in the United States
No full textThe research described in this dissertation explores the impact of cultural definitions of mental health/illness on care-seeking behavior among members of a Latino community living in the United States. Secondary data analysis utilizes survey data from prior research focusing on mental health service needs among Latino community members. The current research is conceptually situated at the juncture of several topics of current interest within sociology. The social construction of mental illness and cultural influences on that construction has gained importance as current topics within the broader sociological rubric of culture and cognition. The research also addresses challenges confronting mental health service providers created by a rapidly growing and increasingly diverse American population requiring appropriate cross-cultural approaches to meet their mental health service needs. Qualitative data presented in this dissertation illuminate several key concerns regarding the Latino community and community members’ recognition of, and reaction to, symptoms of mental disorder. These results underscore how Latino community members conceptualize emotional/mental problems in ways that differ from members of the majority Non-Latino White population living in the U.S. Quantitative analyses of the impact of demographic variables on Latino community members’ reports of alternative beliefs about the causes of emotional/mental problems show that three of the variables (age, education, and time living in U.S.) are significant predictors of subjects’ alternative explanations for the cause of emotional/mental problems. Analyses of the impact of Latino community members’ causal definition of emotional/mental problems also show significant relationships between the definition and Latino community members’ perceptions and behaviors related to mental disorder. I discuss the ‘Latino Paradox’ and propose an alternative explanation based on community members’ shared cultural constructs regarding mental health and illness for the apparently lower rate of mental disorder among recently arrived Latino immigrants. I offer recommendations suggested by my research findings that relate to mental health services for Latino community members, and for additional research topics.Ph.D.Includes bibliographical referencesIncludes vitaby Frederick O. Rasmusse
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