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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
461

Using EWGM Method to Optimise the FMEA as a Risk Assessment Methodology

AL Mashaqbeh, S., Munive-Hernandez, J. Eduardo, Khan, M. Khurshid 26 March 2019 (has links)
Yes / Failure Modes and Effect Analysis (FMEA) is a proactive, highly structured, and systematic approach for failure analysis. It has been also applied as a risk assessment tool, by ranking potential risks based on the estimation of Risk Priority Numbers (RPNs). This paper develops an improved FMEA methodology for strategic risk analysis. The proposed approach combines the Analytic Hierarchy Process (AHP) technique with the Exponential and Weighted Geometric Mean method (EWGM) to support risk analysis. AHP is applied to estimate the weights of three risk factors: Severity (S), Occurrence (O) and Detection (D), which integrate the RPN for each risk. The EWGM method is applied for ranking RPNs. Combining AHP with EWGM allows avoiding repetition of FMEA results. The results of the developed methodology reveal that duplication of RPNs has been decreased, and facilitating an effective risk ranking by offering a unique value for each risk. The proposed methodology focuses not only on high severity values for risk ranking but also it considers other risk factors (O and D), resulting in an enhanced risk assessment process. Furthermore, the weights of the three risk factors are considered. In this way, the developed methodology offers unique value for each risk in a simple way which makes the risk assessment results more accurate. This methodology provides a practical and systematic approach to support decision-makers in assessing and ranking risks that could affect long-term strategy implementation. The methodology was validated through the case study of a power plant in the Middle East, assessing 84 risks within 9 risk categories. The case study revealed that top management should pay more attention to key risks associated with electricity price, gas emissions, lost-time injuries, bad odor, and production. / This research has been supported by Hashemite University, Jordan.
462

Developing a FMEA Methodology to Assess Non-Technical Risks in Power Plants

AL Mashaqbeh, S., Munive-Hernandez, J. Eduardo, Khan, M. Khurshid 14 April 2018 (has links)
Yes / Risk Management is one of the most relevant approaches and systematic application of strategies, procedures and practices management that have been introduced in literature to identifying and analysing risks which exist through the whole life of a product or a process. As a quality management tool, the novelty of this paper suggests a modified Failure Modes and Effect Analysis (FMEA) for understanding the non-technical risk comprehensively, and to attain a systemic methodology by decomposing the risk for nine risk categories including an appropriate 84 Risk Indicators (RI's) within all those categories through the Life Cycle (LC) stages of power plants. These risk categories have been identified as: economic risks, environmental and safety health risks, social risks, technological risks, customer/demand risks, supply chain risks, internal and operational business process risks, human resources risks and management risks. These indicators are collected from literatures. The enhanced FMEA has combined the exponential and the weighted geometric mean (WGM) to calculate the Exponential Weighted Geometric Mean-RPN (EWGM-RPN). The EWGM-RPN can be used to evaluate the risk level, after which the high-risk areas can be determined. Subsequently, effective actions either preventive or corrective can be taken in time to reduce the risk to an acceptable level. However, in this paper the FMEA will not adapt an action plan. Due to that, all RPN's will be considered depending on the point scale (1 to 5) afterward, the results will be combined and extended later with AHP. This developed methodology is able to boost effective decision- making about risks, improve the awareness towards the risk management at power plants, and assist the top management to have an acceptable and preferable understanding of the organisation than lower level managers do who are close to the day-to-day (tactical plan). Additionally, this will support the organisation to develop strategic plans which are for long term. And the essential part of applying this methodology is the economic benefit. Also, this paper includes developed sustainability perspective indicators with a new fourth pillar, which is the technological dimension. The results of the analysis show that the potential strategic makers should pay special attention to the environmental and internal and operational business process risks. The developed methodology will be applied and validated for different power plants in the Middle East. An expanded validation is required to completely prove drawbacks and benefits after completing the Analytical Hierarchy Process (AHP) model. / Hashemite University, Jordan
463

Neurocognition of Food Decision-Making and Eating Behaviour: Neural Correlates and Methodological Advancements

Thieleking, Ronja Geneviève 06 November 2024 (has links)
Motivated by the rising prevalence of obesity worldwide and the global need for greater sustainability, I dedicated this dissertation to exploring new perspectives on food decision-making and to advancing neuroimaging and food-related research methods. Despite the awareness that unfavourable food choices can have serious long-term consequences on individual health and on the environment, people often struggle to break out of their dietary habits. Vicious cycles seem to inhibit individuals from shifting to healthier, more sustainable diets. Successful therapies and policies are required to prevent the pandemic development of obesity. Hence, there is an acute need to understand the complex mosaic of food choices, including cognitive, physiological and neuroanatomical factors. Using a randomized controlled trial (RCT) and diffusion-weighted magnetic resonance imaging (DWI), I was able to uncover a so far undetected potentially vicious cycle of reward-enhanced and calorie-biased food recognition memory. Consequently, the reward- and calorie-bias combined with the over-representation of high-caloric food in our environment might be inhibiting healthier food choices. On the neural level, I assessed the microstructural coherence of the uncinate fasciculus (UF) which connects reward with memory brain areas. The UF's coherence did not influence the enhancement of memory by 'desire-to-eat' in our healthy, overweight study participants. Weight-loss interventions could profit from reward-enhanced memorability by promoting the desire to eat healthier food options. In obese individuals, though, white matter coherence is often decreased and could counteract the success of such interventions. To facilitate and encourage further research on eating behaviour and interventions, I co-developed methodological advancements such as food-related tasks for MRI use, an open-access stimulus database, a tool to evaluate nutrient intake, and the extension of a food picture database by important characteristics. As DWI revealed to be noise- and artefact-sensitive, I also aimed to optimize DWI processing pipelines, namely artefact reduction and white matter skeleton reconstruction. Replicability and sustainability efforts in this dissertation are reflected in the choice of statistical tools and application of Open Science practices.:1 Introduction 1.1 The scope of food decisions 1.1.1 Individuals and their well-being and health 1.1.2 Societal well-being and functioning 1.1.3 Environment and climate change 1.2 The cognition of food decisions 1.2.1 Neural mechanisms of food choices 1.2.2 Food decision-making in obesity 1.3 The research on food decision-making—Methods and Tools 1.3.1 Assessing dietary habits and food intake 1.3.2 Functional neuroimaging 1.3.3 Experimental stimuli 1.3.4 Diffusion-weighted imaging of brain microstructure 1.3.5 Statistical Analysis 1.4 Interim Summary 2 Publications 2.1 art.pics Database: An Open Access Database for Art Stimuli for Experimental Research. 2.2 Same Brain, Different Look?—The Impact of Scanner, Sequence and Preprocessing on Diffusion Imaging Outcome Parameters. 2.3 Nutrient scoring for the DEGS1-FFQ—from food intake to nutrient intake. 2.4 Neurocognitive predictors of food memory in healthy adults—a preregistered analysis. 3 Conclusions Summary Neurocognitive determinants of food memory Implications for the obesity pandemic DWI in Neuroimaging Stimuli in Neuroimaging Food and nutrient intake assessment Open Science and Sustainability References Darstellung des eigenen Beitrags Erklärung über die eigenständige Abfassung der Arbeit Curriculum vitae Verzeichnis der wissenschaftlichen Veröffentlichungen und Vorträge Danksagung / Motiviert durch die steigende Prävalenz von Adipositas weltweit und den globalen Bedarf an mehr Nachhaltigkeit widmete ich diese Dissertation der Erforschung neuer Perspektiven auf Essentscheidungen und der Weiterentwicklung von Methoden zur Hirnbildgebung und Erforschung von Ernährung. Obwohl bekannt ist, dass ungünstige Nahrungswahl langfristig gravierende Folgen für die individuelle Gesundheit und die Umwelt haben kann, fällt es Menschen oft schwer, ihre Ernährungsgewohnheiten zu ändern. Teufelskreise scheinen Individuen daran zu hindern, zu gesünderen, nachhaltigeren Ernährungsweisen zu wechseln. Erfolgreiche Therapien und politische Maßnahmen sind erforderlich, um den globalen Anstieg von Adipositas zu verhindern. Daher besteht ein akuter Bedarf, das komplexe Mosaik der Essentscheidungen zu verstehen, einschließlich kognitiver, physiologischer und neuroanatomischer Faktoren. Durch eine randomisierte kontrollierte Studie und diffusionsgewichtete Magnetresonanztomographie (dwMRT) konnte ich einen bislang unentdeckten potenziellen Kreislauf des belohnungsverstärkten und kalorienverzerrten Lebensmittelgedächtnis aufdecken. Diese Kombination aus Belohnungs- und Kalorienbias, zusammen mit der Überrepräsentation hochkalorischer Lebensmittel in unserer Umgebung, könnte gesündere Essentscheidungen behindern. Auf neuronaler Ebene evaluierte ich die mikrostrukturelle Kohärenz des Fasciculus uncinatus (FU), der Belohnungs- mit Gedächtnisarealen des Gehirns verbindet. Die Kohärenz des FU hatte keinen Einfluss auf die Verstärkung des Gedächtnisses durch das „Verlangen zu essen“ bei unseren übergewichtigen Studienteilnehmenden, da deren Nervenfasern noch gesund waren. Gewichtsreduktionstherapien könnten daher von der belohnungsverbesserten Einprägsamkeit profitieren, indem sie das Verlangen nach gesünderen Nahrungsmitteln fördern. Bei Personen mit Adipositas ist die Kohärenz der weißen Substanz jedoch oftmals verringert, was den Erfolg solcher Interventionen schon beeinträchtigen könnte. Um weitere Forschung zu Essverhalten und Interventionen zu erleichtern und zu fördern, entwickelte ich Methoden wie Aufgaben zu Essentscheidungen und Essensgedächtnis für die Verwendung im MRT, eine öffentlich zugängliche Stimulusdatenbank, ein Tool zur Auswertung der Nährstoffaufnahme und die Erweiterung einer Lebensmitteldatenbank um wichtige Merkmale. Da sich dwMRT als anfällig für Rauschen und Artefakte erwies, hatte ich auch das Ziel, die dwMRT-Verarbeitungs-Pipelines zu optimieren, insbesondere die Artefaktreduzierung und die Rekonstruktion der Nervenbahnen der weißen Substanz. Die Reproduzierbarkeits- und Nachhaltigkeitsbemühungen dieser Dissertation spiegeln sich in der Wahl der statistischen Methoden und der Anwendung von Open-Science-Praktiken wider.:1 Introduction 1.1 The scope of food decisions 1.1.1 Individuals and their well-being and health 1.1.2 Societal well-being and functioning 1.1.3 Environment and climate change 1.2 The cognition of food decisions 1.2.1 Neural mechanisms of food choices 1.2.2 Food decision-making in obesity 1.3 The research on food decision-making—Methods and Tools 1.3.1 Assessing dietary habits and food intake 1.3.2 Functional neuroimaging 1.3.3 Experimental stimuli 1.3.4 Diffusion-weighted imaging of brain microstructure 1.3.5 Statistical Analysis 1.4 Interim Summary 2 Publications 2.1 art.pics Database: An Open Access Database for Art Stimuli for Experimental Research. 2.2 Same Brain, Different Look?—The Impact of Scanner, Sequence and Preprocessing on Diffusion Imaging Outcome Parameters. 2.3 Nutrient scoring for the DEGS1-FFQ—from food intake to nutrient intake. 2.4 Neurocognitive predictors of food memory in healthy adults—a preregistered analysis. 3 Conclusions Summary Neurocognitive determinants of food memory Implications for the obesity pandemic DWI in Neuroimaging Stimuli in Neuroimaging Food and nutrient intake assessment Open Science and Sustainability References Darstellung des eigenen Beitrags Erklärung über die eigenständige Abfassung der Arbeit Curriculum vitae Verzeichnis der wissenschaftlichen Veröffentlichungen und Vorträge Danksagung
464

Το πρόβλημα Fermat-Torricelli και ένα αντίστροφο πρόβλημα στο Κ-επίπεδο και σε κλειστά πολύεδρα του R^3

Ζάχος, Αναστάσιος 18 September 2014 (has links)
Το πρόβλημα Fermat-Torricelli για n μη συγγραμμικά σημεία με βαρύτητες στον R^3 (b.FT) διατυπώνεται ως εξής: Δοθέντος n μη συγγραμμικών σημείων στον R^3 να βρεθεί ένα σημείο το οποίο ελαχιστοποιεί το άθροισμα των αποστάσεων με θετικές βαρύτητες του σημείου αυτού από τα n δοσμένα σημεία. Το αντίστροφο πρόβλημα Fermat-Torricelli για n μη συγγραμμικά και μη συνεπίπεδα σημεία με βαρύτητες στον R^3 (αντ.FT) διατυπώνεται ως εξής: Δοθέντος ενός σημείου που ανήκει στο εσωτερικό ενός κλειστού πολυέδρου που σχηματίζεται από n δοσμένα μη συγγραμμικά και μη συνεπίπεδα σημεία στον R^3, υπάρχει μοναδικά προσδιορίσιμο σύνολο τιμών για τις βαρύτητες που αντιστοιχούν σε κάθε ένα από τα n δοσμένα σημεία, ώστε το σημείο αυτό να επιλύει για τις τιμές αυτές των βαρυτήτων το πρόβλημα b.FT στον R^3; Στην παρούσα διατριβή, αποδεικνύουμε μία γενίκευση της ισογώνιας ιδιότητας του σημείου b.FT για ένα γεωδαισιακό τρίγωνο σε ένα Κ-επίπεδο (Σφαίρα, Υπερβολικό επίπεδο, Ευκλείδειο επίπεδο). Στη συνέχεια, δίνουμε μία αναγκαία συνθήκη για να είναι το σημείο b.FT εσωτερικό σημείο ενός τετραέδρου και ενός πενταέδρου (πυραμίδες) στον R^3. Η δεύτερη ομάδα αποτελεσμάτων της διατριβής περιλαμβάνει τη θετική απάντηση στο αντ.FT πρόβλημα για τρία μη γεωδαισιακά σημεία στο Κ-επίπεδο και στο αντ.FT πρόβλημα για τέσσερα μη συγγραμμικά και μη συνεπίπεδα σημεία στον R^3. Η αρνητική απάντηση στο αντ.FT για τέσσερα μη συγγραμμικά σημεία στον R^2 θα μας οδηγήσει σε σχέσεις εξάρτησης των βαρυτήτων που ονομάζουμε εξισώσεις της δυναμικής πλαστικότητας των τετραπλεύρων. Ομοίως, δίνοντας αρνητική απάντηση στο αντ.FT πρόβλημα για πέντε μη συνεπίπεδα σημεία στον R^3, παίρνουμε τις εξισώσεις δυναμικής πλαστικότητας , διατυπώνουμε και αποδεικνύουμε την αρχή της πλαστικότητας των κλειστών εξαέδρων στον R^3, που αναφέρει ότι: Έστω ότι πέντε προδιαγεγραμμένα ευθύγραμμα τμήματα συναντώνται στο σημείο b.FT, των οποίων τα άκρα σχηματίζουν ένα κλειστό εξάεδρο. Επιλέγουμε ένα σημείο σε κάθε ημιευθεία που ορίζει το προδιαγεγραμμένο ευθύγραμμο τμήμα, τέτοιο ώστε το τέταρτο σημείο να βρίσκεται πάνω από το επίπεδο που σχηματίζεται από την πρώτη και δεύτερη προδιαγεγραμμένη ημιευθεία και το τρίτο και πέμπτο σημείο να βρίσκονται κάτω από το επίπεδο που σχηματίζεται από την πρώτη και δεύτερη προδιαγεγραμμένη ημιευθεία. Τότε η μείωση της τιμής της βαρύτητας που αντιστοιχεί στην πρώτη, τρίτη και τέταρτη προδιαγεγραμμένη ημιευθεία προκαλεί αύξηση στις βαρύτητες που αντιστοιχούν στη δεύτερη και πέμπτη προδιαγεγραμμένη ημιευθεία.Τέλος, ένα σημαντικό αποτέλεσμα της διατριβής αφορά την επίλυση του γενικευμένου προβλήματος του Gauss για κυρτά τετράπλευρα στο Κ-επίπεδο, θέτοντας δύο σημεία στο εσωτερικό του κυρτού τετραπλεύρου με ίσες βαρύτητες, τα οποία στη συνέχεια αποδεικνύουμε ότι είναι δύο σημεία b.FT με συγκεκριμμένες βαρύτητες, αποτέλεσμα το οποίο γενικεύει το πρόβλημα b.FT για τετράπλευρα στο Κ-επίπεδo. / The weighted Fermat-Torricelli for n non-collinear points in R^3 states the following: Given n non-collinear points in R^3 find a point (b.FT point) which minimizes the sum of the distances multiplied by a positive number which corresponds to a given point (weight). The inverse Fermat-Torricelli problem for n non-collinear points with weights in R^3 (inv.FT) states the following: Given a point that belongs to the interior of a closed polyhedron which is formed between n given non-collinear points in R^3, does there exist a unique set of weights which corresponds to each one of the n points such that this point solves the weighted Fermat-Torricelli problem for this particular set of weights? In the present thesis, we prove a generalization of the isogonal property of the b.FT point for a geodesic triangle on the K-plane (Sphere, Hyperbolic plane, Euclidean plane). We proceed by giving a sufficient condition to locate the b.FT point at the interior of tetrahedra and pentahedra (pyramids) in R^3. The second group of results contains a positive answer on the inv.FT problem for three points that do not belong to a geodesic arc on the K-plane and on the inv.FT problem for four non collinear points and non coplanar in R^3. The negative answer with respect to the inv.FT problem for four non-collinear points in R^2 lead us to the relations of the dependence between the weights that we call the equations of dynamic plasticity for quadrilaterals. Similarly, by giving a negative answer with respect to the inv.FT problem for five points which do not belong in the same plane in R^3, we derive the equations of dynamic plasticity of closed hexahedra and we prove a plasticity principle of closed hexahedra in R^3, which states that: Considering five prescribed rays which meet at the weighted Fermat-Torricelli point, such that their endpoints form a closed hexahedron, a decrease on the weights that correspond to the first, third and fourth ray, causes an increase to the weights that correspond to the second and fifth ray, where the fourth endpoint is upper from the plane which is formed from the first ray and second ray and the third and fifth endpoint is under the plane which is formed from the first ray and second ray. Finally, a significant result of this thesis deals with the solution of the generalized Gauss problem for convex quadrilaterals on the K-plane in which by setting two points at the interior of the convex quadrilateral with equal weights we prove that these points are weighted Fermat-Torricelli points with specific weights, that generalizes the b.FT problem for quadrilaterals on the K-plane.
465

Geographically weighted spatial interaction (GWSI)

Kordi, Maryam January 2013 (has links)
One of the key concerns in spatial analysis and modelling is to study and analyse similarities or dissimilarities between places over geographical space. However, ”global“ spatial models may fail to identify spatial variations of relationships (spatial heterogeneity) by assuming spatial stationarity of relationships. In many real-life situations spatial variation in relationships possibly exists and the assumption of global stationarity might be highly unrealistic leading to ignorance of a large amount of spatial information. In contrast, local spatial models emphasise differences or dissimilarity over space and focus on identifying spatial variations in relationships. These models allow the parameters of models to vary locally and can provide more useful information on the processes generating the data in different parts of the study area. In this study, a framework for localising spatial interaction models, based on geographically weighted (GW) techniques, has been developed. This framework can help in detecting, visualising and analysing spatial heterogeneity in spatial interaction systems. In order to apply the GW concept to spatial interaction models, we investigate several approaches differing mainly in the way calibration points (flows) are defined and spatial separation (distance) between flows is calculated. As a result, a series of localised geographically weighted spatial interaction (GWSI) models are developed. Using custom-built algorithms and computer code, we apply the GWSI models to a journey-to-work dataset in Switzerland for validation and comparison with the related global models. The results of the model calibrations are visualised using a series of conventional and flow maps along with some matrix visualisations. The comparison of the results indicates that in most cases local GWSI models exhibit an improvement over the global models both in providing more useful local information and also in model performance and goodness-of-fit.
466

Spatially Explicit Modeling of West Nile Virus Risk Using Environmental Data

Kala, Abhishek K. 12 1900 (has links)
West Nile virus (WNV) is an emerging infectious disease that has widespread implications for public health practitioners across the world. Within a few years of its arrival in the United States the virus had spread across the North American continent. This research focuses on the development of a spatially explicit GIS-based predictive epidemiological model based on suitable environmental factors. We examined eleven commonly mapped environmental factors using both ordinary least squares regression (OLS) and geographically weighted regression (GWR). The GWR model was utilized to ascertain the impact of environmental factors on WNV risk patterns without the confounding effects of spatial non-stationarity that exist between place and health. It identifies the important underlying environmental factors related to suitable mosquito habitat conditions to make meaningful and spatially explicit predictions. Our model represents a multi-criteria decision analysis approach to create disease risk maps under data sparse situations. The best fitting model with an adjusted R2 of 0.71 revealed a strong association between WNV infection risk and a subset of environmental risk factors including road density, stream density, and land surface temperature. This research also postulates that understanding the underlying place characteristics and population composition for the occurrence of WNV infection is important for mitigating future outbreaks. While many spatial and aspatial models have attempted to predict the risk of WNV transmission, efforts to link these factors within a GIS framework are limited. One of the major challenges for such integration is the high dimensionality and large volumes typically associated with such models and data. This research uses a spatially explicit, multivariate geovisualization framework to integrate an environmental model of mosquito habitat with human risk factors derived from socio-economic and demographic variables. Our results show that such an integrated approach facilitates the exploratory analysis of complex data and supports reasoning about the underlying spatial processes that result in differential risks for WNV. This research provides different tools and techniques for predicting the WNV epidemic and provides more insights into targeting specific areas for controlling WNV outbreaks.
467

Optimisation de la performance environnementale des activités agricoles à l’échelle d’un espace à enjeux : le cas du bassin versant de la Boulouze

Darradi, Younès 09 February 2011 (has links)
Les travaux présentés dans cette thèse portent sur la notion de performance environnementale comme cadre analytique pour l’étude des impacts des activités agricoles sur l’environnement. Après avoir mis en évidence un manque de formalisation de cette notion dans la littérature, nous la définissons comme la distance entre l’état environnemental d’un écosystème à un moment donné et un état environnemental à atteindre pour cet écosystème, dit « de haute performance environnementale ». Dans cette étude, l’état environnemental est approché par trois critères liés à la ressource « eau » : les concentrations en nitrates et en matières en suspension, et les débits.Suite à la description de l’état initial, nous proposons une méthode d’optimisation de la performance environnementale des activités agricoles basée sur un couplage entre un modèle agro-hydrologique (SWAT) et un modèle d’optimisation multicritère (Weighted Goal Programming). La démarche d’optimisation considère la réaffectation spatialisée de systèmes de culture sur l’espace considéré comme facteur d’amélioration, les différents critères de l’optimisation étant examinés simultanément.La méthode est implémentée sur le bassin versant de la Boulouze (coteaux de Gascogne). Les résultats montrent une amélioration de la performance environnementale du système étudié. L’analyse de la nouvelle occupation des sols souligne qu’au-delà des évolutions quantitatives des surfaces allouées aux systèmes de culture, la spatialisation des changements d’un système vers un autre influe également sur la performance environnementale à l’échelle du bassin versant. Enfin, nous interrogeons l’applicabilité de cette méthode et mettons en évidence l’intérêt qu’elle présente comme outil à la fois de modélisation de scénarios et de communication. / We introduce in this thesis the notion of environmental performance as an analytical framework aimed at studying the impacts of agricultural activities on the environment. We outline first a need to formalize this notion and then define it as the distance between the “environmental” state of a system at a specific time and a state of “high environmental performance” to achieve. Focus is on water management at the watershed level with three criteria: nitrogen, sediments (water quality) and water flows (water quantity).Our aim is to optimize the environmental performance of agricultural activities at the watershed scale. First the initial status of the watershed is described, then a method is proposed. This method is based on a coupling between an agro-hydrological model, the Soil and Water Assessment Tool (SWAT), and the Weighted Goal Programming optimization method. Our purpose is the reallocation of farming systems within the watershed when considering the optimization criteria simultaneously.We implement this method on the Boulouze watershed (coteaux de Gascogne, in the southwestern part of France). Results outline an improvement of the environmental performance. The analysis of the new land-use plan emphasizes the fact that the changes of farming systems are not only due to evolutions of the surfaces where they are implemented, but that the environmental performance at watershed scale is also affected by their location.Finally we explore the applicability of the method used highlighting its attributes as a relevant tool for modeling scenarios and for communicating.
468

Diffusion-weighted MRI reflects proliferative activity in primary CNS lymphoma

Schob, Stefan, Meyer, Jonas, Gawlitza, Matthias, Frydrychowicz, Clara, Müller, Wolf, Preuss, Matthias, Bure, Lionel, Quäschling, Ulf, Hoffmann, Karl-Titus, Surov, Alexey 22 September 2016 (has links) (PDF)
Purpose: To investigate if apparent diffusion coefficient (ADC) values within primary central nervous system lymphoma correlate with cellularity and proliferative activity in corresponding histological samples. Materials and Methods: Echo-planar diffusion-weighted magnetic resonance images obtained from 21 patients with primary central nervous system lymphoma were reviewed retrospectively. Regions of interest were drawn on ADC maps corresponding to the contrast enhancing parts of the tumors. Biopsies from all 21 patients were histologically analyzed. Nuclei count, total nuclei area and average nuclei area were measured. The proliferation index was estimated as Ki-67 positive nuclei divided by total number of nuclei. Correlations of ADC values and histopathologic parameters were determined statistically. Results: Ki-67 staining revealed a statistically significant correlation with ADCmin (r = -0.454, p = 0.038), ADCmean (r = -0.546, p = 0.010) and ADCmax (r = -0.515, p = 0.017). Furthermore, ADCmean correlated in a statistically significant manner with total nucleic area (r = -0.500, p = 0.021). Conclusion: Low ADCmin, ADCmean and ADCmax values reflect a high proliferative activity of primary cental nervous system lymphoma. Low ADCmean values—in concordance with several previously published studies—indicate an increased cellularity within the tumor.
469

Analyse des tendances et configurations de la criminalité au Québec à l’aide d’un indice de gravité de la criminalité

Goupil, Jean-Philippe 04 1900 (has links)
La mesure traditionnelle de la criminalité (taux pour 100 000 habitants) pose problème dans l'analyse des variations de la criminalité dans le temps ou l'espace. Le problème est dû au fait que le taux de criminalité est essentiellement déterminé par des infractions moins graves et très fréquentes. La présente étude a permis de tester l’utilité du nouvel outil développé par Statistique Canada qui procure un index de « gravité de la criminalité » dans lequel chaque crime est pondéré par son score de gravité (basé sur les décisions sentencielles moyennes au Canada de 2002 à 2007 pour chaque forme de crime). Appliquées aux statistiques officielles du Québec de 1977 à 2008, nos analyses montrent que l’indice de gravité s’avère une mesure utile pour dresser un portrait plus juste des tendances des crimes violents d’une année à l’autre. Plus exactement, l’indice de gravité montre que le taux de crimes violents est demeuré stable de 1977 à 1992 contrairement à l'image fournie par le taux traditionnel qui montre plutôt une montée fulgurante durant cette période. L’indice de gravité peut également être utile à l’égard des crimes violents pour comparer plus adéquatement les territoires entre eux afin d’établir ceux qui présentent une criminalité plus grave. Cependant, à l’égard de la criminalité globale et des crimes sans violence, l’indice de gravité n’est d’aucune utilité et présente la même lecture de la criminalité que la mesure traditionnelle. Cela s’explique par le fait que ce sont toujours les mêmes infractions (les vols, les méfaits et les introductions par effraction) qui contribuent majoritairement à chacune des deux mesures de la criminalité. / The traditional measure of the criminality (rate for 100 000 inhabitants) raises problem in the analysis of the variations of the criminality in time or space. The problem is due to the fact that the rate of criminality is essentially determined by less serious and very frequent crimes. The present study allowed testing the utility of a new tool developed by Statistics Canada which gets an index of "severity of criminality" in which every crime is weighted by its score of severity (based on the sentencielles decisions average in Canada from 2002 till 2007 for every kind of crime. Applied to the official statistics of Quebec from 1977 till 2008, our analyses show that the indication of gravity turns out to be a useful measure to draw up a more realistic portrait of the trends of violent crimes from one year to the next. More precisely, the crime seriousness index shows that the rate of violent crimes remained stable from 1977 till 1992, on contradiction to what is shown by traditional rate which rather demonstrates a huge rise during this period. Crime seriousness index can also be used towards violent crimes, in order to compare more adequately territories, to establish those who show more serious crimes. However, among global criminality and crimes without violence, the indication of gravity is of no utility and presents the same reading of the criminality as traditional measures. It explains that it is always the same crimes (thefts, mischief and breaking and entering) that contribute mainly to each of both measures of the criminality.
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An adaptive autopilot design for an uninhabited surface vehicle

Annamalai, Andy S. K. January 2014 (has links)
An adaptive autopilot design for an uninhabited surface vehicle Andy SK Annamalai The work described herein concerns the development of an innovative approach to the design of autopilot for uninhabited surface vehicles. In order to fulfil the requirements of autonomous missions, uninhabited surface vehicles must be able to operate with a minimum of external intervention. Existing strategies are limited by their dependence on a fixed model of the vessel. Thus, any change in plant dynamics has a non-trivial, deleterious effect on performance. This thesis presents an approach based on an adaptive model predictive control that is capable of retaining full functionality even in the face of sudden changes in dynamics. In the first part of this work recent developments in the field of uninhabited surface vehicles and trends in marine control are discussed. Historical developments and different strategies for model predictive control as applicable to surface vehicles are also explored. This thesis also presents innovative work done to improve the hardware on existing Springer uninhabited surface vehicle to serve as an effective test and research platform. Advanced controllers such as a model predictive controller are reliant on the accuracy of the model to accomplish the missions successfully. Hence, different techniques to obtain the model of Springer are investigated. Data obtained from experiments at Roadford Reservoir, United Kingdom are utilised to derive a generalised model of Springer by employing an innovative hybrid modelling technique that incorporates the different forward speeds and variable payload on-board the vehicle. Waypoint line of sight guidance provides the reference trajectory essential to complete missions successfully. The performances of traditional autopilots such as proportional integral and derivative controllers when applied to Springer are analysed. Autopilots based on modern controllers such as linear quadratic Gaussian and its innovative variants are integrated with the navigation and guidance systems on-board Springer. The modified linear quadratic Gaussian is obtained by combining various state estimators based on the Interval Kalman filter and the weighted Interval Kalman filter. Change in system dynamics is a challenge faced by uninhabited surface vehicles that result in erroneous autopilot behaviour. To overcome this challenge different adaptive algorithms are analysed and an innovative, adaptive autopilot based on model predictive control is designed. The acronym ‘aMPC’ is coined to refer to adaptive model predictive control that is obtained by combining the advances made to weighted least squares during this research and is used in conjunction with model predictive control. Successful experimentation is undertaken to validate the performance and autonomous mission capabilities of the adaptive autopilot despite change in system dynamics.

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