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1
Diaz, Gabriel D. „Identifying the method for effective combat marksmanship training using site optics and packaged sensor feedback“. Thesis, Monterey, California. Naval Postgraduate School, 2011. http://hdl.handle.net/10945/5607.
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Approved for public release; distribution is unlimited.The Marine Corps is assessing how shooters train for Combat Marksmanship. An implementation of the Rifle Combat Optics (RCO) has been introduced into the Annual Rifle Qualification requirement. The question now is, How do coaches modify training to effectively instruct the shooters in firing with the RCO? This study provides feedback using the Split Shot Scope System as an aid in training doctrinal techniques for marksmanship on live fire ranges. The assessments, provided by current Marine Corps Marksmanship Instructors, highlight a necessity to using a device such as the Split Shot Scope System. In a postsurvey conducted in the study, responses provide a viable path to employing this diagnostic tool during live fire shooting and reporting the level of utility of this device. Added, in this study, is the use of a sensor package derived from concepts of the Indoor Simulated Marksmanship Trainer (ISMT), which will be discussed to provide the utility of such a device for improving and defining a useful technique for training shooters. While this may not be a complete fix to the dilemma, this study has provided an approach to understanding and deriving methods for effective marksmanship training and diagnosing fundamental problems more clearly.
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Jacobsen, Olov. „Autonomous Underwater Cable Suspended Dredging System : A method to combat the eutrophication of the Baltic Sea“. Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-175883.
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An autonomous underwater cable suspended dredging system is proposed with the application of combating the excess of nutrients in the Baltic Sea. The focus of the thesis is on modelling and designing of the control system used to guide an end-effector supplied with a pump along a predetermined path. The end-effector is guided with the help of four cables that are each controlled by a servomotor. The buoyancy of the end-effector in combination with the cables keeps the end-effector a few meter above the seafloor. The sediment is collected with tubes hanging down from the end-effector. Due to the large dimensions of the system a combination of force control and position control passed through a force distribution algorithm is suggested. A simulation of the system shows promising results with ability to trace the predetermined path closely.Ett förslag till ett autonomt vajerstyrt muddringssytem för undervattensbruk har tagits fram som ska används för att motverka övergödningen i östersjön. Uppsatsen fokuserar på modelleringen och designen av reglersystemet för att styra en plattform utrustad med en pump längs en förutbestämd sträcka. Plattformen styrs med hjälp av fyra vajrar som i sin tur styrs av varsin servomotor. Flytkraften hos plattformen i kombination med vajrarna håller plattformen några meter från havsbotten. Bottensediment pumpas upp genom slangar som hänger ner från plattformen. På grund av systemet storlek regleras styrningen av plattformen genom båda kraft och position samt använder en algoritm för att distribuera krafterna mellan vajrarna. En simulering av systemet har utförts och visar på god förmåga att reglera positionen av plattformen i relation till den förutbestämda sträckan.
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Li, Yingping. „Artificial intelligence and radiomics in cancer diagnosis“. Electronic Thesis or Diss., université Paris-Saclay, 2022. http://www.theses.fr/2022UPASG053.
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L'intelligence artificielle (IA) est très utilisée pour le diagnostic et le traitement de données médicales, donnant lieu à la médecine personnalisée assistée par l'IA. Ce manuscrit se concentre sur la proposition et l'analyse de méthodes d'IA, notamment l'apprentissage profond et la radiomique, pour le diagnostic du cancer. Tout d'abord, une approche efficace de segmentation automatique est essentielle pour mettre en place une méthode de diagnostic par IA, car c'est un préalable à une analyse par radiomiques. Nous avons proposé une nouvelle approche pour la segmentation automatique des lésions dans les images échographiques, basée sur des données multicentrique et multipathologique présentant différents types de cancers. En introduisant la convolution de groupe, nous avons proposé un réseau U-net léger en mémoire sans sacrifier les performances de segmentation. Deuxièmement, nous nous sommes intéressés au traitement de données d'imagerie par résonance magnétique (IRM) pour prédire de manière non invasive le sous-type de gliome, défini par le grade de la tumeur, la mutation de l'isocitrate déshydrogénase (IDH) et la codélétion 1p/19q. Nous proposons une approche par radiomiques. La performance de prédiction s'est améliorée de manière significative en optimisant différents paramètres de notre modèle. Les caractéristiques des éléments radiomiques qui distinguent le mieux les sous-types de gliome ont également été analysées. Ce travail a non seulement fourni un pipeline qui fonctionne bien pour prédire le sous-type de gliome, mais il a également contribué au développement et à l'interprétabilité du modèle radiomique. Troisièmement, nous nous intéressons à la problématique de reproductibilité des approches basées sur les radiomiques. Nous avons donc étudié l'impact de différentes méthodes de prétraitement d'images et de méthodes d'harmonisation (y compris la normalisation de l'intensité et l'harmonisation ComBat) sur la reproductibilité des caractéristiques radiomiques en IRM. Nous avons montré que la méthode ComBat est essentielle pour éliminer la variation non biologique causée par les différents paramètres d'acquisition d'image (à savoir, les effets du scanner) et améliorer la reproductibilité des caractéristiques dans les études radiomiques. Nous avons illustré l'importance de la normalisation de l'intensité, car elle permet d'obtenir des images IRM plus comparables et des résultats plus robustes. Enfin, nous avons cherché à améliorer la méthode ComBat en modifiant l'hypothèse classique, à savoir que les effets du scanner sont différents pour différentes classes (comme les tumeurs et les tissus normaux). Bien que le modèle proposé donne des résultats encore décevants, sûrement en raison du manque de contraintes appropriées pour aider à identifier les paramètres, il a néanmoins ouvert la voie à des perspectives intéressantesArtificial intelligence (AI) has been widely used in the research field of AI-assisted diagnosis, treatment, and personalized medicine. This manuscript focuses on the application of artificial intelligence methods including deep learning and radiomics in cancer diagnosis. First, effective image segmentation is essential for cancer diagnosis and further radiomics-based analysis. We proposed a new approach for automatic lesion segmentation in ultrasound images, based on a multicentric and multipathology dataset displaying different types of cancers. By introducing the group convolution, we proposed a lightweight U-net network without sacrificing the segmentation performance. Second, we processed the clinical Magnetic Resonance Imaging (MRI) images to noninvasively predict the glioma subtype as defined by the tumor grade, isocitrate dehydrogenase (IDH) mutation and 1p/19q codeletion status. We proposed a radiomics-based approach. The prediction performance improved significantly by tuning different settings in the radiomics pipeline. The characteristics of the radiomic features that best distinguish the glioma subtypes were also analyzed. This work not only provided a radiomics pipeline that works well for predicting the glioma subtype, but it also contributed to the model development and interpretability. Third, we tackled the challenge of reproducibility in radiomics methods. We investigated the impact of different image preprocessing methods and harmonization methods (including intensity normalization and ComBat harmonization) on the radiomic feature reproducibility in MRI radiomics. The conclusion showed that ComBat method is essential to remove the nonbiological variation caused by different image acquisition settings (namely, scanner effects) and improve the feature reproducibility in radiomics studies. Meanwhile, intensity normalization is also recommended because it leads to more comparable MRI images and more robust harmonization results. Finally, we investigated improving the ComBat harmonization method by changing its assumption to a very common case that scanner effects are different for different classes (like tumors and normal tissues). Although the proposed model yielded disappointing results, surely due to the lack of enough proper constraints to help identify the parameters, it still paved the way for the development of new harmonization methods
4
Nelson, Michael S. „Graphical methods for depicting combat units“. Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23913.
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5
Sällberg, Benny. „Applied methods to combat noise in human communication /“. Karlskrona : Department of Telecommunication Systems, School of Engineering, Blekinge Institute of Technology, 2006. http://www.bth.se/fou/Forskinfo.nsf/Sok/d2c91ae695e01b8bc12571dc0069837c!OpenDocument.
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Keane, Therese Alison Mathematics & Statistics Faculty of Science UNSW. „Combat modelling with partial differential equations“. Awarded By:University of New South Wales. Mathematics & Statistics, 2009. http://handle.unsw.edu.au/1959.4/43086.
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In Part I of this thesis we extend the Lanchester Ordinary Differential Equations and construct a new physically meaningful set of partial differential equations with the aim of more realistically representing soldier dynamics in order to enable a deeper understanding of the nature of conflict. Spatial force movement and troop interaction components are represented with both local and non-local terms, using techniques developed in biological aggregation modelling. A highly accurate flux limiter numerical method ensuring positivity and mass conservation is used, addressing the difficulties of inadequate methods used in previous research. We are able to reproduce crucial behaviour such as the emergence of cohesive density profiles and troop regrouping after suffering losses in both one and two dimensions which has not been previously achieved in continuous combat modelling. In Part II, we reproduce for the first time apparently complex cellular automaton behaviour with simple partial differential equations, providing an alternate mechanism through which to analyse this behaviour. Our PDE model easily explains behaviour observed in selected scenarios of the cellular automaton wargame ISAAC without resorting to anthropomorphisation of autonomous 'agents'. The insinuation that agents have a reasoning and planning ability is replaced with a deterministic numerical approximation which encapsulates basic motivational factors and demonstrates a variety of spatial behaviours approximating the mean behaviour of the ISAAC scenarios. All scenarios presented here highlight the dangers associated with attributing intelligent reasoning to behaviour shown, when this can be explained quite simply through the effects of the terms in our equations. A continuum of forces is able to behave in a manner similar to a collection of individual autonomous agents, and shows decentralised self-organisation and adaptation of tactics to suit a variety of combat situations. We illustrate the ability of our model to incorporate new tactics through the example of introducing a density tactic, and suggest areas for further research.
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Goza, Tracy H. „Combat Near-Death Experiences: An Exploratory, Mixed-Methods Study“. Thesis, University of North Texas, 2011. https://digital.library.unt.edu/ark:/67531/metadc84208/.
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This mixed-methods study’s purpose was a systematic comparison of contents and aftereffects of near-death experiences (NDEs) occurring in a variety of circumstances with those occurring in combat. They completed an online survey: a demographic questionnaire, the Near-Death Experience Scale, the Life Changes Inventory-Revised (LCI-R), and four narrative response items. Survey completers were 68 participants: 20 combat near-death experiencers (cNDErs) and 48 non-NDErs (nNDErs). The 29% of participants who met NDE Scale criterion for an NDE was comparable to NDE incidence findings from previous retrospective studies. For statistical analyses, significance was set at p < .05, and effect size (Cohen’s d) was calculated. Mean total NDE Scale scores were significantly lower for cNDErs than variety-of-circumstance NDErs from one of two comparable studies (t = 5.083, p < .0001, d = -1.26), possibly suggesting cNDEs may have “less depth” than other-variety NDEs. Regarding cNDE aftereffects, absence of previous LCI-R data made comparison impossible. Cronbach’s alpha analysis yielded acceptable reliability on the total scale and seven of nine subscales, a finding that matched Schneeberger’s (2010); however, factor analytic results did not support the hypothesized subscale structure of the LCI-R. Although cNDErs did not score significantly higher than nNDErs on the total scale or subscales after Bonferroni correction, results indicated a possible trend toward greater absolute changes (p = 0.02, d = 0.74) and spirituality (p = 0.02, d = 0.67) with the latter finding substantiated by narrative responses. Informal analysis of narrative responses yielded several themes.
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Generazio, Hòa. „Consistency of representation for disaggregation from constructive to virtual combat simulations“. Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/30773.
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Druga, David A. „Feasibility of combat hemostasis methods in civilian prehospital emergency medical care“. Thesis, Boston University, 2012. https://hdl.handle.net/2144/12353.
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Thesis (M.A.)--Boston UniversityUncontrolled hemorrhage is the leading cause of preventable traumatic death in both military and civilian populations. Hemorrhage often causes coagulopathy, which intensifies hemorrhage and complicates its treatment. The armed conflicts in Afghanistan and Iraq have allowed the military to test new hemostatic products and procedures in an effort to better control hemorrhage and reduce its associated morbidity and mortality rates. These methods were analyzed for efficacy and suitability in the civilian prehospital setting. Several invasive and non-invasive interventions were found to be beneficial. Despite centuries of controversy surrounding their use, emergency tourniquets can be safe, lifesaving tools for controlling severe extremity hemorrhage when adequate tourniquet designs are properly used. Hemostatic dressings are very useful as hemorrhage control adjuncts, and two products (Combat Gauze and Celox) are recommended for prehospital use based on their efficacy, mechanisms of action, ease of use, low cost, shelf-life, and other properties. Several pharmacological interventions were evaluated for prehospital use in addressing the anticoagulant and hyperfibrinolytic nature of trauma-associated coagulopathy. Recombinant activated Factor VII, commonly used in hemophiliac-related bleeding, does not improve outcomes in trauma patients. Tranexamic acid, which is commonly used to reduce bleeding in elective surgeries, has been demonstrated to significantly lower mortality in trauma patients with severe hemorrhage, especially when administered within three hours of injury. Recommendations were also made based on the results of military-developed damage control resuscitation protocols: restoration of perfusion is the best way to correct coagulopathy and prehospital fluid administration should be limited to restore perfusion and maintain systolic blood pressures of 80 to 90 mmHg. Hypothermia and hyperthermia are correlated with higher mortality in trauma patients, so temperature management was identified as a top priority in prehospital trauma care. Finally, the properties of stored blood were investigated in the setting of massive transfusion so that paramedics conducting interfacility transfers of these patients could be made aware of common complications to anticipate adverse events.
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Stafford, Charles A. „The relationship between operational graphics and battlefield success“. Thesis, Monterey, Calif. : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA238338.
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Thesis (M.S. in Operations Research)--Naval Postgraduate School, September 1990.Thesis Advisor(s): Read, Robert R. ; Dryer, David A. Second Reader: Whitaker, Lyn R. "September 1990." DTIC Descriptor(s): Army Training, Combat Information Centers, Organizations, Training, Battalion Level Organizations, Battlefields, Task Forces, Attack, Missions, Standards, Graphics, Military Training, Archives, Combat Forces, Discriminate Analysis, Doctrine, Frequency, Data Processing. DTIC Identifier(s): National Training Center, Army Operation. Author(s) subject terms: National Training Center, Deliberate Attack, Operational. Description based on title screen as viewed on Dec. 22, 2009. Includes bibliographical references (p. 82). Also available in print.
11
Moreno, Matthew S. „Modeling and assessment of alternative cooling methods of the Combat Operation Center“. Thesis, Monterey, California. Naval Postgraduate School, 2012. http://hdl.handle.net/10945/27875.
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The Marine Corps Combat Operations Center provides formidable situational awareness and command and control capability using a robust mobile data center. This capability incurs a cost in fuel and restricted mobility due to the size and weight of the cooling and electrical generation. Enhancing the energy efficiency through alternative cooling methods will enhance the Marine Corps tactical flexibility on the battlefield. In both Iraq and Afghanistan, the Improvised Explosive Device threat is of grave concern. Reducing the frequency of fuel convoys may reduce the associated casualties that result. In this research, a model was created to predict potential reduction in fuel consumption by using alternative methods of cooling. The model considers all the sources of heat load introduced into the Combat Operations Center environment and estimates the amount of electricity required to maintain a set point temperature. An alternative method of cooling is introduced to determine whether it has the potential to reduce fuel consumption. A substantive increase in efficiency indicates further research has merit. The model offers an analytical method for exploring alternative cooling methods that may be used either individually or in concert to reduce the fuel required by the Combat Operations Center.
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Banner-Bacin, Linda, Tim Carpenter, David Chacon, James Chandler, James Childs, Tuyen Hoang, Robert Howard et al. „Application of model based systems engineering methods to development of combat system architectures“. Thesis, Monterey, California. Naval Postgraduate School, 2009. http://hdl.handle.net/10945/6938.
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Navy acquisition activities frequently produce combat system architectures based on existing systems rather than stakeholder requirements. This approach limits software component reuse which, in turn, limits potential application to other platforms. The objective of this Capstone project was to develop a methodology for creating complex combat system architectures that emphasize the use of Software Product Lines (SPLs), requirements traceability, integrated supportability and Modeling and Simulation (M&S) early and throughout the approach. To address this objective, an integrated methodology that utilizes Model Based Systems Engineering (MBSE) to create open, supportable combat system architectures was developed. The methodology was evaluated by applying it to a naval surface combatant Anti-Air Warfare (AAW) mission area. Application of the methodology led to the following major findings: (1) Proven systems engineering practices, languages and tools can be integrated with the MBSE approach for developing complex architectures, (2) Creation of domain centered SPLs facilitates planned reuse and allows for assessment to candidate architectures, (3) Requirements traceability can be achieved by using a combination of modeling languages and tools, (4) M&S application can extend beyond operational scenarios to address life cycle cost, and (5) Engineers and logisticians can effectively use MBSE to integrate supportability into design. Overall, this project demonstrated the benefits of an MBSE approach tailored to developing affordable and supportable combat system architectures that meet mission requirements.
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Winn, Linda C. „Combat veterans' perspectives on a dramatherapy journey : a phenomenological mixed methods case study“. Thesis, Anglia Ruskin University, 2016. http://arro.anglia.ac.uk/702160/.
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A review of academic literature revealed a dearth of published research concerning whether dramatherapy might help UK combat veterans recover from Post Traumatic Stress Disorder (PTSD). Furthermore no published research sought to capture veterans’ perspectives during dramatherapy in the UK. My research questions addressed the gap in the research literature: What is the participant’s perspective on the use of dramatherapy in helping British combat veterans a) to recover from PTSD? and b) to adjust to civilian life? The research design was a phenomenological mixed methods case study. The qualitative measures were arts-based. Interpretative Phenomenological Analysis (IPA) was used to examine the transcripts of the dramatherapy sessions. The quantitative measures were the Clinical Outcomes Routine Evaluation (CORE) -34 and CORE-10; Short Warwick Edinburgh Mental Well-being Scale (SWEMWBS) and the PTSD Checklist – Military (PCL-M). The multiple methods synthesis raised questions and gave new insights rather than confirming results. The participants were 3 male veterans from the same region of the UK. I was the researcher/dramatherapist. The aim of the research was to achieve an in-depth study underpinned by a participant-centred approach. The research theme was journeying towards recovery. The choice of play-text, an excerpt from The Odyssey, reflected this. The initial 5 dramatherapy sessions were individual and the remaining 3 were group sessions. The IPA indicated that the participants’ perspectives were that dramatherapy might help other veterans towards recovery from PTS. Furthermore dramatherapy might help in their adjustment to civilian life. The use of , imagination and role rehearsal and assisted in reframing of their personal stories. The participants found the use of a novel method developed by myself, from Turner’s Model of Crisis (TMOC) (Turner, 1967) particularly helpful in moving through traumatic memories, utilising metaphor and a problem-solving approach. This led to embodiment of reprised positive military roles in overcoming obstacles on their journeys. They used this method in other situations arising outside of the research and recommended it as potentially having a positive impact on other veterans, seeking recovery. They remained in the clinically significant scoring for PTSD. However, they identified the framework of dramatherapy methods resulted in an increase in confidence, creativity and ability to manage conflict. This was supported by the IPA results.
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Winn, Linda C. „Combat veterans’ perspectives on a dramatherapy journey: a phenomenological mixed methods case study“. Thesis, Anglia Ruskin University, 2016. https://arro.anglia.ac.uk/id/eprint/702160/1/Winn_2016.pdf.
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A review of academic literature revealed a dearth of published research concerning
whether dramatherapy might help UK combat veterans recover from Post Traumatic Stress
Disorder (PTSD). Furthermore no published research sought to capture veterans’
perspectives during dramatherapy in the UK.
My research questions addressed the gap in the research literature: What is the
participant’s perspective on the use of dramatherapy in helping British combat veterans a)
to recover from PTSD? and b) to adjust to civilian life?
The research design was a phenomenological mixed methods case study. The qualitative
measures were arts-based. Interpretative Phenomenological Analysis (IPA) was used to
examine the transcripts of the dramatherapy sessions. The quantitative measures were the
Clinical Outcomes Routine Evaluation (CORE) -34 and CORE-10; Short Warwick
Edinburgh Mental Well-being Scale (SWEMWBS) and the PTSD Checklist – Military
(PCL-M). The multiple methods synthesis raised questions and gave new insights rather
than confirming results.
The participants were 3 male veterans from the same region of the UK. I was the
researcher/dramatherapist. The aim of the research was to achieve an in-depth study
underpinned by a participant-centred approach.
The research theme was journeying towards recovery. The choice of play-text, an excerpt
from The Odyssey, reflected this.
The initial 5 dramatherapy sessions were individual and the remaining 3 were group
sessions. The IPA indicated that the participants’ perspectives were that dramatherapy
might help other veterans towards recovery from PTS. Furthermore dramatherapy might
help in their adjustment to civilian life. The use of , imagination and role rehearsal and
assisted in reframing of their personal stories. The participants found the use of a novel
method developed by myself, from Turner’s Model of Crisis (TMOC) (Turner, 1967)
particularly helpful in moving through traumatic memories, utilising metaphor and a
problem-solving approach. This led to embodiment of reprised positive military roles in
overcoming obstacles on their journeys. They used this method in other situations arising
outside of the research and recommended it as potentially having a positive impact on
other veterans, seeking recovery.
They remained in the clinically significant scoring for PTSD. However, they identified the
framework of dramatherapy methods resulted in an increase in confidence, creativity and
ability to manage conflict. This was supported by the IPA results.
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Dilanson, Rekar. „Optimering av balkonginfästningar : ComBAR glasfiberförstärkt polymerplast som armering i betong“. Thesis, KTH, Bro- och stålbyggnad, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-155121.
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I samband med EU-direktivs mål att reducera energikonsumtionen med 20 % fram till år 2020 har kraven i Boverkets byggregler skärpts för energianvändningen i Sverige. Dessa krav håller den totala energiförbrukningen i sektorn bostäder och service på jämn nivå trots att det sker en ständig ökning av antalet bostäder. Syftet med detta arbete är att undersöka om det finns möjlighet till att minimera energiförluster i infästningen mellan inspända balkonger och bjälklaget. Detta utfördes för att ge samtliga aktörer inom byggbranschen en uppfattning om hur stor inverkan en optimering av de oftast försummade detaljerna i ett projekt har. Glasfiberförstärkta polymerplaster (GFRP) isolerar ca 120 gånger bättre än konstruktionsstål och klarar samtidigt av att ta upp dragkrafter i en betongkonstruktion om de formas som armeringsstänger. Från ett urval har flera GFRP produkter granskats där ComBAR har valts att studeras och kontrolleras som en ersättningsprodukt för stålarmering i balkonginfästningar. ComBAR uppfyller samtliga konstruktionskrav för att fungera som armering i betong och har egenskaper som är att föredra framför stål vilket även gör den användbar i flera andra konstruktionsdelar i en byggnad eller anläggning. Utförandet av beräkningar och analyser är indelat i tre delar som är analys av byggstatik för att bestämma den erforderlig armering i balkonginfästningen, simulering av energiflöde mellan balkongen och bjälklaget samt ekonomisk kalkyl för att uppskatta avkastningstiden. I den ekonomiska kalkylen knyts resultaten ihop från analysen av byggstatik och beräkning av energiflödet för att sedan kunna avgöra om en investering är lönsam. Ur resultaten från analysen av byggstatik som består av handberäkningar och simuleringar i beräkningsprogrammen Concrete Beam och FEM-Design kan vi dra slutsatsen att det behövs en armeringsstång mindre av ComBAR än stål för att bära upp balkongen i studien. Ur statisk synpunkt är det lämpligt att använda glasfiberbaserade armeringsstänger i balkonginfästningen. Energiflödesberäkningarna har utförts i programmet Comsol för att erhålla ett noggrant resultat på energiflödet igenom infästningen. Återbetalningstiden på över 100 år för det pris som ComBAR ligger på i dagsläget anses inte vara rimligt och det behövs en halvering av priset innan det kan komma på tal att användas.
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Dawson, Dr Gwendolyn B. „Strategies to Combat Tenant Fraud in the Rental Housing Market“. ScholarWorks, 2018. https://scholarworks.waldenu.edu/dissertations/6007.
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Many business executives lack strategies to detect and eliminate tenant fraud in subsidized rental housing. The purpose of this multicase study was to explore strategies some business executives used to detect and eliminate tenant fraud in subsidized rental housing. The conceptual framework used to guide this study was the theory of planned behavior. Data were gathered using semistructured interviews with 6 purposively selected business executives of public housing authorities, supplemented with a review of policies and procedures that business executives used. Yin's 5-step analysis, which entails examining, categorizing, tabulating, creating a data display, and testing the data, guided the process of coding participants' responses. Member checking validated that emerging themes were in alignment with participant experiences. The 4 major themes of the study were: perception of tenant fraud, detection and minimization of fraud, the effect of fraudulent behavior on tenant attitudes and belief systems, and verification procedures. The results of the study might support positive social change by providing leaders with insights related to fraud-reducing fragmentation, duplication, and overlapping of programs, which may result in federal funds being available for federal government public services. The findings of this study might add to the body of knowledge and further contribute to social change through a coalition of housing agencies working together to share their knowledge of combating tenant fraud in subsidized rental housing and restoring the integrity of the Housing Choice Voucher Program.
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Hadidimoud, S. „Modelling local damage and material rupture (using finite element method)“. Thesis, University of Surrey, 2000. http://epubs.surrey.ac.uk/998/.
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Spencer, Rebecca Lyn. „Bibliotherapy and Bullying: Teaching Young Childrento Utilize Peer Group Power to Combat Bullying“. BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3727.
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Bullying is a major concern for school-age children. This study compares the use of bibliotherapy and didactic instruction techniques for teaching anti-bullying strategies to young children. The study explores 36 first graders' perceptions of bullying and their perceptions of their roles and responsibilities in bullying situations. In comparison to the control group, students who were taught specific bully intervention skills, both through didactic instruction and bibliotherapy, reflected an increased understanding of bullying, used a larger bully vocabulary, and demonstrated more specific and varied actions in response to bullying from pre-test to post-test conditions. Participants in the group who received didactic instruction demonstrated more positive change in both describing the concept of bullying (77.2%) and providing adaptive responses to a hypothetical bullying situation (144%) than the bibliotherapy (33.3%, 44%) and control groups (13.4%, -15%), possibly due to the explicit instruction and repetition of concepts students received in the didactic group. These data suggest that children benefit from explicit instruction and rehearsal about how to combat bullying. Recommendations for practice are to schedule more time when planning to use bibliotherapy, to simplify concepts and use repetition, and to integrate social/emotional concepts into regular class activities.
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Sutherland, Duncan. „Numerical study of vortex generation in bounded flows with no-slip and partial slip boundary conditions“. Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/11778.
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The main contributions of this thesis are an investigation of the effect of slip on dipole-wall collisions and a study of topological changes in two-dimensional bounded flows. The Navier-Stokes equations in the streamfunction-vorticity formulation are solved in both a channel domain, periodic in the streamwise direction and also in a disc domain, with either no-slip or Navier boundary conditions. Navier boundary conditions permit some fluid slip along the wall. The normal velocity component at the wall is always zero, but the tangential component of velocity is proportional to the rate of strain at the boundary, with the constant of proportionality identified as the slip length. Recently, Romain Nguyen van yen, Marie Farge, and Kai Schneider, ``Energy dissipating structures produced by walls in two-dimensional flows at vanishing viscosity'', Physical Review Letters, 106:184502, 2011 investigated the problem of a dipole incident on a rigid boundary using a volume penalisation method. The volume penalisation method approximates a no-slip boundary condition and intrinsically introduces some slip at the boundary, which vanishes as the Reynolds number increases. Their results indicate that energy dissipating structures persist in the vanishing viscosity limit. Here a similar problem was investigated using Fourier collocation techniques in the streamwise direction, and a compact finite difference method in the direction normal to the wall. The boundary conditions were enforced using a linear superposition technique called the influence matrix method, modified to treat Navier boundary conditions. For the no-slip boundary condition no evidence of energy dissipating structures was found in the limit as the viscosity approaches zero, and this result also holds for any fixed slip length. However when the slip length was taken to vary inversely with Reynolds number, the results of Nguyen van yen et al were recovered. To investigate the production of enstrophy at the wall it is useful to track the minima, maxima, and saddle points of the vorticity and streamfunction. As coherent structures of vorticity approach near the wall, vorticity is generated at the wall to satisfy the no-slip or Navier boundary conditions and injected into the domain. The flow throughout the domain may be classified into regions dominated by coherent vortices, and regions dominated by filamentary stretching by a condition called the Okubu-Weiss criterion. The Okubu-Weiss criterion can be derived by considering the linear stability of the stagnation points of the flow, and it can be considered as a measure of curvature of the streamfunction. The Gaussian curvature of both the streamfunction and vorticity can be used to directly classify the flow into hyperbolic and elliptical regions. The curvature of the streamfunction is essentially a modification of the Okubu-Weiss criterion and can be interpreted as a balance between vorticity and strain, but the curvature of the vorticity does not appear to have a simple physical interpretation. The Gauss-Bonnet theorem shows that the total Gaussian curvature of both vorticity and streamfunction vanishes for a doubly-periodic domain and for the channel domain. For a disc domain it is possible to derive similar conservation laws. In the channel domain and a disc domain, the total curvature of the streamfunction vanishes, but for the vorticity there is an additional contribution from the curvature of the boundary. The generation and merger of critical points in bounded flows was monitored in an observational study. In an unbounded domain, the well-known forward energy cascade forces energy to large spatial scales. Large numbers of small scale vortices will therefore merge into domain-filling structures. In bounded domains, the wall acts as a source of enstrophy which constantly injects small scale vortices that disturb the formation of organised, domain-filling circulation cells. Fayeza Al Sulti and Koji Ohkitani, ``Vortex merger and topological changes in two-dimensional turbulence'', Physical Review E, 86.1 016309, 2012 studied vortex merger in unbounded domains by counting the number of elliptic and hyperbolic critical points of vorticity and streamfunction. To identify and classify the critical points Al Sulti and Ohkitani used the zeros of gradient of the field and the eigenvalues of the Hessian matrix at those points. In this thesis a new algorithm is developed, based on estimating the the Poincaré-Hopf index near potential critical points. This algorithm avoids the difficulties of identifying the zeros of gradient of the field, instead only local minima are required. Results showing the motion of critical points in time and the variation in the number of critical points over the simulation for a channel geometry are presented. In addition to the overall theme of the effect of the boundary conditions on the interior flow, the influence matrix method has been improved into a powerful and efficient numerical method for studying viscous fluid flow. The extension to generalised boundary conditions also allows a careful comparison of the volume penalisation method, with its intrinsic approximation to no-slip boundary conditions, against methods that enforce the no-slip boundary conditions exactly.
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Busta, Michal. „Analýza namáhání vybraných konstrukčních částí bagru při provozu“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443770.
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This thesis is focused on the issue of computational modeling of soil harvesting while using the compact excavator from the company DOOSAN BOBCAT EMEA s.r.o.. The solution consists in creating two computational models in Rocky DEM and Ansys Mechanical. Rocky DEM software is used to solve the disconnection of soil by excavator components using the discrete element method. The outcome includes courses of forces and moments during the particular time of the individual joints of the model that was used. The obtained courses are then applied as an external load to the joint of a selected structural part of the analyzed model using a kinematic model in ANSYS Mechanical. The kinematic model consists of simplified geometry models of individual parts of the excavator arm, and a more detailed geometry model of the analyzed part of the arm. All the parts are connected to each other by rotational bonds representing joints. A static structural analysis of the mechanical stress is performed in ANSYS Mechanical for the prepared model during the simulated process. Finally, the selected structural part is assessed with respect to the elastic limit and fatigue strength.
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Lauer, Rafael Nuernberg. „O esporte como meio de prevenção e combate ao uso de drogas: análise de um discurso“. Universidade do Estado do Rio de Janeiro, 2009. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=5156.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorA ideia de que drogas e esportes caminhem em sentidos opostos parece ser senso comum na sociedade brasileira: o esporte se associa à saúde, à cidadania e à liberdade; a droga à degradação, à violência e ao vício. A relação entre o esporte e a droga se resume, nesse sentido, em uma postura maniqueísta que parece advir da observação em separado destes dois fenômenos e não da própria relação entre os mesmos. Apesar da existência de uma extensa bibliografia referente às temáticas da droga e do esporte, foi observada, conforme o levantamento da literatura pertinente, uma carência de pesquisas que abordem o uso do esporte como meio de prevenção e diminuição do consumo de drogas. O objetivo deste estudo foi analisar os fundamentos do discurso em prol do esporte enquanto instrumento capaz de combater e prevenir o uso de drogas. Para tanto, foram analisados os seguintes documentos: Política Nacional do Esporte; Política Nacional Sobre Drogas; Carta Brasileira de Prevenção Integrada da Área da Saúde na Perspectiva da Educação Física. A metodologia utilizada foi a da Análise do Discurso preconizada por Orlandi (2001). A interpretação dos dados se realizou segundo os fundamentos do campo interdisciplinar do Imaginário Social. Os resultados da pesquisa mostraram que a relação entre o esporte e a droga materializa um conflito de forças entre as atitudes prometeica e dionisíaca. De modo que o esporte, representando um instrumento de afirmação dos valores prometeicos, se opõe à droga, associada à dissociação destes valores por meio da manifestação dionisíaca.
The idea that drugs and sports go in opposite directions seems to be common sense in Brazilian society: the sport is associated with health, citizenship and freedom, the degradation of drugs, violence and addiction. The relationship between sports and drugs is summarized in this sense, in a Manichean attitude that seems to result from the observation of these two separate phenomena and not the actual relationship between them. Despite the extensive literature relating to issues of drugs and sports, was seen as lifting the relevant literature, a lack of research that address the use of sport as a means of prevention and reduction of drug consumption. The objective of this research was to analyze the fundamentals of speech for the sport as a means of combating and preventing the use of drugs. Thus, we analyzed the following documents: the National Sports Policy, National Policy on Drugs; Brazilian Charter on the Prevention Integrated Area Health Education Physics in Perspective. The methodology used was the analysis of discourse advocated by Orlandi (2001). The interpretation of the data held on the grounds of the interdisciplinary field of social imaginary. The survey results showed that the relationship between sport and drug substance of a conflict between the forces and attitudes dionysiac promised. So that the sport, an instrument of affirmation of the values promised, as opposed to drugs, associated with the dissociation of these values through the dionysiac expression.
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Silverberg, Jon P. „On Lagrangian meshless methods in free-surface flows“. Thesis, (1.7 MB), 2005. http://edocs.nps.edu/AR/topic/theses/2005/Jan/05Jan_Silverberg.pdf.
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Thesis (Master of Engineering in Ocean Engineering)--University of California at Berkeley, 2004."January 2005." Description based on title screen as viewed on May 25, 2010. DTIC Descriptor(s): Fluid Dynamics, Lagrangian Functions, Equations Of Motion, Acceleration, Formulations, Grids, Continuum Mechanics, Gaussian Quadrature, Derivatives (Mathematics), Compact Disks, Boundary Value Problems, Polynomials, Interpolation, Pressure, Operators (Mathematics). DTIC Identifier(s): Multimedia (CD-Rom), Moving Grids, Meshless Discretization, Lifs (Lagrange Implicit Fraction Step), Lagrangian Dynamics, Meshless Operators, Mlip (Multidimensional Lagrange Interpolating Polynomials), Flux Boundary Conditions, Radial Basis Functions Includes bibliographical references (58-59).
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Stålberg, Erik. „A high order method for simulation of fluid flow in complex geometries“. Licentiate thesis, KTH, Mechanics, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-322.
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A numerical high order difference method is developed for solution of the incompressible Navier-Stokes equations. The solution is determined on a staggered curvilinear grid in two dimensions and by a Fourier expansion in the third dimension. The description in curvilinear body-fitted coordinates is obtained by an orthogonal mapping of the equations to a rectangular grid where space derivatives are determined by compact fourth order approximations. The time derivative is discretized with a second order backward difference method in a semi-implicit scheme, where the nonlinear terms are linearly extrapolated with second order accuracy.
An approximate block factorization technique is used in an iterative scheme to solve the large linear system resulting from the discretization in each time step. The solver algorithm consists of a combination of outer and inner iterations. An outer iteration step involves the solution of two sub-systems, one for prediction of the velocities and one for solution of the pressure. No boundary conditions for the intermediate variables in the splitting are needed and second order time accurate pressure solutions can be obtained.
The method has experimentally been validated in earlier studies. Here it is validated for flow past a circular cylinder as an example of a physical test case and the fourth order method is shown to be efficient in terms of grid resolution. The method is applied to external flow past a parabolic body and internal flow in an asymmetric diffuser in order to investigate the performance in two different curvilinear geometries and to give directions for future development of the method. It is concluded that the novel formulation of boundary conditions need further investigation.
A new iterative solution method for prediction of velocities allows for larger time steps due to less restrictive convergence constraints.
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Malmqvist, Philip. „Monitoring of crack growth and crack mouth opening displacement in compact tension specimens at high temperatures : Development and implementation of the Direct Current Potential Drop (DCPD) method“. Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-44493.
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The mechanical engineering department at the University of Idaho is conducting a project with the purpose of developing a complete system for investigating creep-, creep-fatigue- and fatigue properties of metallic materials at elevated temperatures up to 650 ˚C with Compact Tension (CT) specimens. Considerable efforts have been made to study and understand these phenomena, although numerous problems still exist. It is important to explore more extensively the complicated phenomena of creep, fatigue and of creep-fatigue interactions. The Direct Current Potential Drop (DCPD) method is a common method used to investigate, for example, the initiation of cracks, crack growth rates and to monitor crack growth. The technique utilizes the fact that the electrical resistance of a CT specimen changes with crack growth. By applying a constant current over the specimen and measuring the resulting voltage over the crack, the crack length can be related to the voltage, and the difference in crack length with difference in voltage. Standards from the American Society for Testing of Materials (ASTM) were used as guidance when designing the DCPD system and CT specimen. The development and implementation processes were divided into an analytical and an experimental stage. The final product consisted of a high temperature extensometer, to measure crack mouth opening displacement (CMOD), and a DCPD system, to measure crack growth, controlled by separate control units. The DCPD system consisted of a DC supply and a nano voltmeter along with Constantan wire and NiCr60 wire respectively, that were mechanically fastened. The DCPD system delivered overall satisfying results and was able to generate sufficient data to produce a crack growth curve, da/dN vs. ΔK. Although, by taking advantage of resistance welding equipment to attach the DCPD wires, along with implementing one shared control unit for the DCPD system and the extensometer, more accurate and accessible measurements and correlations could be extracted.Mechanical engineering avdelningen på University of Idaho genomför just nu ett utvecklingsprojekt med syftet att utveckla ett komplett system för undersökning av krypnings, krypnings-utmattnings- samt utmattnings- egenskaper av metalliska material vid höga temperaturer upp till 650 ˚C med hjälp av kompakta spänningsprovstavar (CT specimens). Betydande ansträngningar har gjorts för att undersöka och förstå dessa fenomen, men flera problem kvarstår. Det är viktigt att djupare undersöka kopplingen mellan krypnings- och utmattningsegenskaper. Direct Current Potential Drop (DCPD) metoden är en vanlig metod vilken används för att undersöka, exempelvis, sprickinitiering, spricktillväxthastigheter och spricktillväxt. Tekniken utnyttjar faktumet att den elektriska resistansen i en provstav ändras med spricktillväxt. Genom att föra en konstant ström genom provstaven och sedan mäta den resulterande spänningen över sprickan, kan spricklängden relateras till uppmätt spänning. På samma sätt kan spricktillväxt relateras till spänningsförändringar. Standarder från American Society for Testing of Materials (ASTM) användes för att designa ett DCPD system samt en CT provstav. Utvecklings- och implementeringsprocessen var uppdelad i en analytisk och en experimentell del. Den slutgiltiga produkten bestod av en extensometer, för mätning av spricköppning vid höga temperaturer, och ett DCPD system, för mätning av spricktillväxt vid höga temperaturer, vilka kontrollerades av separata kontrollenheter. DCPD systemet bestod av en strömkälla och en nanovoltmeter tillsammans med Constantan kablar respektive NiCr60 kablar, vilka fastsättes mekaniskt. DCPD systemet levererade generellt sett tillfredställande resultat och hade kapacitet att generera tillräckligt precisa data för att producera en spricktillväxtkurva, da/dN vs. ΔK. Däremot, genom att utnyttja en resistanssvets, för att fastsätta DCPD-kablarna, tillsammans med en gemensam kontrollenhet för extensometern och DCPD systemet, kan det tänkas att bättre och mer tillgängliga resultat kunde åstadkommas.
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Lenaers, Peter. „A new high-order method for direct numerical simulations of turbulent wall-bounded flows“. Doctoral thesis, KTH, Turbulens, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-142374.
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A new method to perform direct numerical simulations of wall-bounded flows has been developed and implemented. The method uses high-order compact finite differences in wall-normal (for channel flow) or radial direction (for pipe flow) on a collocated grid, which gives high-accuracy results without the effectfof filtering caused by frequent interpolation as required on a staggered grid. The use of compact finite differences means that extreme clustering near the wall leading to small time steps in high-Reynolds number simulations is avoided. The influence matrix method is used to ensure a completely divergence-freesolution and all systems of equations are solved in banded form, which ensures an effcient solution procedure with low requirements for data storage. The method is unique in the sense that exactly divergence-free solutions on collocated meshes are calculated using arbitrary dffierence matrices. The code is validated for two flow cases, i.e. turbulent channel and turbulent pipe flow at relatively low Reynolds number. All tests show excellent agreement with analytical and existing results, confirming the accuracy and robustness ofthe method. The next step is to eciently parallelise the code so that high-Reynolds number simulations at high resolution can be performed. We furthermore investigated rare events occurring in the near-wall region of turbulent wall-bounded flows. We find that negative streamwise velocities and extreme wall-normal velocity uctuations are found rarely (on the order of 0:01%), and that they occur more frequently at higher Reynolds number. These events are caused by strong vortices lying further away from the wall and it appears that these events are universal for wall-bounded flows.QC 20150303
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Kong, Xiangxiong, Jian Li, William Collins, Caroline Bennett, Simon Laflamme und Hongki Jo. „A robust signal processing method for quantitative high-cycle fatigue crack monitoring using soft elastomeric capacitor sensors“. SPIE-INT SOC OPTICAL ENGINEERING, 2017. http://hdl.handle.net/10150/625834.
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A large-area electronics (LAE) strain sensor, termed soft elastomeric capacitor (SEC), has shown great promise in fatigue crack monitoring. The SEC is capable to monitor strain changes over a large structural surface and undergo large deformations under cracking. Previous tests verified that the SEC can detect and localize fatigue cracks under low-cycle fatigue loading. In this paper, we further investigate the SEC's capability for monitoring high-cycle fatigue cracks, which are commonly seen in steel bridges. The peak-to-peak amplitude (pk-pk amplitude) of the SEC measurement is proposed as an indicator of crack growth. This technique is is robust and insensitive to long-term capacitance drift. To overcome the difficulty of identifying the pk-pk amplitude in time series due to high signal-to-noise ratio, a signal processing method is established. This method converts the measured SEC capacitance and applied load to power spectral densities (PSD) in the frequency domain, such that the pk-pk amplitudes of the measurements can be accurately extracted. Finally, the performance of this method is validated using a fatigue test of a compact steel specimen equipped with a SEC. Results show that the crack growth under high-cycle fatigue loading can be successfully monitored using the proposed signal processing method.
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Dremkova, Ekaterina. „A high order compact method for nonlinear Black-Scholes option pricing equations with transaction costs“. Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-3198.
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In this work we consider the nonlinear case of Black-Scholes equation and apply it to American options. Also, method of Liao and Khaliq of high order was applied to nonlinear Black-Scholes equation in case of American options. Here, we use this method oh fourth order in time and space to raise American option price accuracy.
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Pereira, Fábio Rafael Miranda. „Equity Research - Sumol+Compal, S. A“. Master's thesis, Instituto Superior de Economia e Gestão, 2017. http://hdl.handle.net/10400.5/14527.
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Mestrado em FinançasEste projeto contém uma avaliação detalhada e respetiva estimação do valor intrínseco das ações da Sumol+Compal, relativamente ao fim do ano de 2017, de acordo com o projeto final do Mestrado de Finanças do ISEG. Este relatório segue o formato recomendado pelo Instituto CFA. Sumol+Compal foi escolhida devido ao interesse pela indústria das bebidas, em geral, assim como pela notável reputação da empresa. As premissas consideradas para a avaliação, resultaram de uma análise aprofundada da informação histórica da empresa, das tendências da indústria e das projeções macroeconómicas. O preço-alvo foi obtido através de um método de avaliação absoluto, mais especificamente o método do Adjusted Present Value (APV). Adicionalmente, foi utilizado um método de avaliação relativo, o método dos Múltiplos Comparáveis. Uma análise de sensibilidade e uma simulação de Monte Carlo foram realizadas com vista a complementar a análise. Com um preço-alvo de €1.93 para o FA2017, representando um potencial de valorização de 16.90%, face ao preço atual de €1.65, do dia 12 de outubro de 2017, a nossa recomendação final para a Sumol+Compal é MANTER, tendo em consta os riscos que poderão ocorrer e afetar o desempenho da empresa. A nossa avaliação do risco estima um risco médio para a empresa.
This project contains the detailed valuation and the respective estimation of Sumol+Compal´s intrinsic share value for the end of 2017, according to ISEG's Master in Finance final work project. This report follows the recommended format by the CFA Institute. Sumol+Compal was chosen due to the interest for the beverage industry in general and due to the remarkable company's reputation. The assumptions considered for the valuation, result from a deep analysis of the company's historical data, industry's trends and macroeconomic projections. The price target was obtained through an absolute valuation method, more specifically the Adjusted Present Value (APV) method. In addition was used a relative valuation method, the Comparable Multiples method. A sensitivity analysis and a Monte Carlo simulation were performed to further complement the analysis. With a price target of €1.93 for YE2017, representing an upside potential of 16.90% from October 12th, 2017, current price of €1.65, our final recommendation for Sumol+Compal is to HOLD, taking into consideration, the risks that may occur and that can affect the company's performance. Our risk assessment estimates a medium risk for the company.
info:eu-repo/semantics/publishedVersion
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Saxton, Aaron. „Decay Estimates on Trace Norms of Localized Functions of Schrödinger Operators“. UKnowledge, 2014. http://uknowledge.uky.edu/math_etds/19.
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In 1973, Combes and Thomas discovered a general technique for showing exponential decay of eigenfunctions. The technique involved proving the exponential decay of the resolvent of the Schrödinger operator localized between two distant regions. Since then, the technique has been been applied to several types of Schrödinger operators. This dissertation will show that the Combes--Thomas method works well with trace, Hilbert--Schmidt and other trace-type norms. The first result we prove shows exponential decay on trace-type norms of a resolvent of a Schrödinger operator localized between two distant regions. We build on this result by applying the Combes--Thomas method again to prove polynomial and sub-exponential decay estimates on functions of Schrödinger operators localized between two distant regions.
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Masson, Anne-Sophie. „Le droit de la guerre confronté aux nouveaux conflits asymétriques : généralisation à partir du conflit Afghan (2001-2013)“. Thesis, Normandie, 2017. http://www.theses.fr/2017NORMLH03.
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Le conflit afghan (à partir de 2001) peut être considéré comme un nouveau conflit asymétrique reprenant les caractéristiques des conflits asymétriques classiques (rapport de force disproportionné entre les belligérants) à l’exception de la territorialisation, remplacée par l’appartenance à une idéologie commune. En conséquence, le champ de bataille y est devenu secondaire, la guerre est devenue cognitive. La séparation entre la paix et la guerre s’est atténuée à tel point qu’il est devenu impossible de compartimenter le droit de la guerre en fonction de l’intensité du conflit ou de son internationalisation. Faute de s’y être adapté, le droit de la guerre a cessé de faciliter le rétablissement de la paix et a été perçu par les militaires occidentaux comme une entrave aux combats. C’est pourquoi, certains belligérants ont tenté de s’en affranchir en ayant recours à des méthodes de combats illégitimes. Ces effets ont été médiatisés et ont participé à la perte de légitimité des Etats occidentaux allant jusqu’à remettre en question la division du monde en Etats souverains. L’absence de résolution de ces conflits pourrait conduire à une guerre civile globalisée. En réponse, l’harmonisation du droit de la guerre autour de la garantie inconditionnelle des droits inaliénables doit être affirmée par les Etats et les nouveaux acteurs internationaux. Elle pourrait émerger d’un « Parlement mondial », garant du droit international. De plus, l’irréprochabilité morale des belligérants est attendue. Le droit et la place des armées au sein de la société doivent le refléterThe Afghan war (since 2001) may be seen as a new asymmetric conflict. It has all characteristics of the former asymmetric conflicts except territoriality, which has been replaced by ideology. Therefore, the battlefields have been displaced to the cognitive war. The distinction between war and peace became so small that it is now impossible to distinguish the law of war in regard to its intensity or to the implication of several states. The law of wars, due to its lack of adaptation stopped to ease the peace recovery, becoming a hindrance to combat. In consequence, some warriors have been tempted to use forbidden combat methods. Whose effects have been mediatized and took part of the western states legitimacy crisis (and questionning the World division in sovereign states). The lack of conflicts settlement could lead to a worldwide civil war. Unless, law of wars are harmonized through universal core rights mandatory for states and new international actors; a “World Parliament” could protect them. Furthermore, moral integrity of warriors is expected, it may be reflected into the military laws and their position into the civil society
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Grimich, Karim. „Schémas compacts basés sur le résidu d'ordre élevé pour des écoulements compressibles instationnaires. Application à de la capture de fines échelles“. Thesis, Paris, ENSAM, 2013. http://www.theses.fr/2013ENAM0033/document.
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Les solveurs de calcul en mécanique des fluides numérique (solveurs CFD) ont atteint leur maturité en termes de précision et d'efficacité de calcul. Toutefois, des progrès restent à faire pour les écoulements instationnaires surtout lorsqu'ils sont régis par de grandes structures cohérentes. Pour ces écoulements, les solveurs CFD actuels n'apportent pas de solutions assez précises à moins d'utiliser des maillages très fins. De plus, la haute précision est une caractéristique cruciale pour l'application des stratégies avancées de simulation de turbulence, comme la Simulation des Grandes Echelles (LES). Afin d'appliquer les méthodes d'ordre élevé pour les écoulements instationnaires complexes plusieurs points doivent être abordés dont la robustesse numérique et la capacité à gérer des géométries complexes.Dans cette thèse, nous étudions une famille d'approximations compactes qui offrent une grande précision non pour chaque dérivée spatiale traitée séparement mais pour le résidu r complet, c'est à dire la somme de tous les termes des équations considérées. Pour des problèmes stationnaires résolus par avancement temporelle, r est le résidu à l'état stationnaire ne comprenant que des dérivées spatiales; pour des problèmes instationnaires r comprend également la dérivée temporelle. Ce type de schémas sont appelés schémas Compacts Basés sur le Résidu (RBC). Plus précisément, nous développons des schémas RBC d'ordre élevé pour des écoulements instationnaires compressibles, et menons une étude approfondie de leurs propriétés de dissipation. Nous analysons ensuite les erreurs de dissipation et la dispersion introduites par les schémas RBC afin de quantifier leur capacité à résoudre une longueur d'onde donnée en utilisant un nombre minimal de points de maillage. Les capacités de la dissipation de RBC à drainer seulement l'énergie aux petites échelles sous-résolues sont également examinées en vue de l'application des schémas RBC pour des simulations LES implicites (ILES). Enfin, les schémas RBC sont étendus à la formulation de type volumes finis (FV) afin de gérer des géométries complexes. Une formulation FV des schémas RBC d'ordre trois préservant une précision d'ordre élevé sur des maillages irréguliers est présentée et analysée. Des applications numériques, dont la simulation d'écoulements instationnaires complexes de turbomachines régis par les équations de Navier-Stokes moyennées et des simulations ILES d'écoulements turbulents dominés par des structures cohérentes dynamiques ou en décroissance, confirment les résultats théoriquesComputational Fluid Dynamics (CFD) solvers have reached maturity in terms of solution accuracy as well as computational efficiency. However, progress remains to be done for unsteady flows especially when governed by large, coherent structures. For these flows, current CFD solvers do not provide accurate solutions unless very fine mesh are used. Moreover, high-accuracy is a crucial feature for the application of advanced turbulence simulation strategies, like Large Eddy Simulation (LES). In order to apply high-order methods to complex unsteady flows several issues needs to be addressed among which numerical robustness and the capability of handling complex geometries.In the present work, we study a family of compact approximations that provide high accuracy not for each space derivative treated apart but for the complete residual r, i.e. the sum of all of the terms in the governing equations. For steady problems solved by time marching, r is the residual at steady state and it involves space derivatives only; for unsteady problems, r also includes the time derivative. Schemes of this type are referred-to as Residual-Based Compact (RBC). Precisely, we design high-order finite difference RBC schemes for unsteady compressible flows, and provide a comprehensive study of their dissipation properties. The dissipation and dispersion errors introduced by RBC schemes are investigated to quantify their capability of resolving a given wave length using a minimal number of grid-points. The capabilities of RBC dissipation to drain energy only at small, ill-resolved scales are also discussed in view of the application of RBC schemes to implicit LES (ILES) simulations. Finally, RBC schemes are extended to the Finite Volume (FV) framework in order to handle complex geometries. A high-order accuracy preserving FV formulation of the third-order RBC scheme for general irregular grids is presented and analysed. Numerical applications, including complex Reynolds-Averaged Navier-Stokes unsteady simulation of turbomachinery flows and ILES simulations of turbulent flows dominated by coherent structure dynamics or decay, support the theoretical results
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Danius, Lena. „Data uncertinties in material flow analysis.Local case study and literature survey“. Licentiate thesis, KTH, Chemical Engineering and Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1502.
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The aim of this thesis is to discuss and analyse the influenceof data uncertainties with regard to the reliability of materialflow analysis (MFA) studies. MFA, as a part of environmentalsystems analysis, is a method belonging to the research field ofindustrial ecology and more specifically industrial metabolism.As such, the method strives at giving a holistic view of thecomplex world we live in, in order to reduce negativeenvironmental impact. Among other things, MFA studies have beenproposed to be useful for priority setting and following up inmunicipalities.
Serving as a starting point is a local case study of flows ofnitrogen in a Swedish municipality, Västerås. The casestudy has been performed using the ComBoxmodel. The years studiedare 1995 and 1998. The main sectors in society emitting nitrogento water were identified as the agricultural and householdsectors. The dominating sectors emitting nitrogen to air wereidentified as the agricultural, transport and infrastructuresectors.
As a basis for discussing data uncertainties qualitatively andquantitatively a literature survey was performed. 50 articles andbooks were identified as in some way or another dealing with datauncertainties in MFA. The literature survey showed that theuncertainties for results from a MFA study might vary between±30 % and a factor 10 depending on what kind of parameter isinvestigated. Only one method was found that dealt with datauncertainties in MFA in a complete way; a model developed byHedbrant and Sörme (HS model).
When applying the HS model to the case study of nitrogen flowsin Västerås, it was found that when uncertaintyintervals were calculated the possible conclusions changed. Ofthe two pair of flows compared in relation to priority setting,none of the earlier conclusions remained. Of the three flowsanalysed in relation to following up, only the flow from onepoint source supported the same conclusion when uncertainty wasconsidered.
In all, it is concluded that data uncertainties in MFAanalysis are an important aspect and that further research isneeded in order to improve input data quality estimations andframeworks for determining, calculating and presenting data, datauncertainties and results from MFA studies. However, theunderlying reality remains, e.g. that management of materialflows are important for understanding and reducing the negativeenvironmental impact. Thus, MFA is one useful tool in thiswork.
Keywords:data uncertainties, sensitivity analysis,Material flow analysis, MFA, method to determine datauncertainties, case study, ComBox model, nitrogenflows.
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Dai, Ruxin. „Richardson Extrapolation-Based High Accuracy High Efficiency Computation for Partial Differential Equations“. UKnowledge, 2014. http://uknowledge.uky.edu/cs_etds/20.
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In this dissertation, Richardson extrapolation and other computational techniques are used to develop a series of high accuracy high efficiency solution techniques for solving partial differential equations (PDEs).
A Richardson extrapolation-based sixth-order method with multiple coarse grid (MCG) updating strategy is developed for 2D and 3D steady-state equations on uniform grids. Richardson extrapolation is applied to explicitly obtain a sixth-order solution on the coarse grid from two fourth-order solutions with different related scale grids. The MCG updating strategy directly computes a sixth-order solution on the fine grid by using various combinations of multiple coarse grids. A multiscale multigrid (MSMG) method is used to solve the linear systems resulting from fourth-order compact (FOC) discretizations. Numerical investigations show that the proposed methods compute high accuracy solutions and have better computational efficiency and scalability than the existing Richardson extrapolation-based sixth order method with iterative operator based interpolation.
Completed Richardson extrapolation is explored to compute sixth-order solutions on the entire fine grid. The correction between the fourth-order solution and the extrapolated sixth-order solution rather than the extrapolated sixth-order solution is involved in the interpolation process to compute sixth-order solutions for all fine grid points. The completed Richardson extrapolation does not involve significant computational cost, thus it can reach high accuracy and high efficiency goals at the same time.
There are three different techniques worked with Richardson extrapolation for computing fine grid sixth-order solutions, which are the iterative operator based interpolation, the MCG updating strategy and the completed Richardson extrapolation. In order to compare the accuracy of these Richardson extrapolation-based sixth-order methods, truncation error analysis is conducted on solving a 2D Poisson equation. Numerical comparisons are also carried out to verify the theoretical analysis.
Richardson extrapolation-based high accuracy high efficiency computation is extended to solve unsteady-state equations. A higher-order alternating direction implicit (ADI) method with completed Richardson extrapolation is developed for solving unsteady 2D convection-diffusion equations. The completed Richardson extrapolation is used to improve the accuracy of the solution obtained from a high-order ADI method in spatial and temporal domains simultaneously. Stability analysis is given to show the effects of Richardson extrapolation on stable numerical solutions from the underlying ADI method.
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Cerciliar, Ellen Thais Alves. „Esquema compacto de diferenças finitas de alta ordem em malhas hierárquicas“. Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/45/45132/tde-07052018-124115/.
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Este trabalho propõe um esquema de diferenças finitas compacta de alta ordem para resolver problemas elípticos com coeficientes variáveis em malhas composta. São apresentados a formulação matemática e a dedução do método compacto de quarta ordem aplicado à problemas elípticos bidimensionais, em malha regular e composta. Foi adotado o uso da biblioteca PETSc com os seus pré-condicionadores e métodos numéricos para resolver os sistemas lineares resultantes da discretização do problema. Por fim, testes visando verificar o código foram feitos, utilizando o método de soluções manufaturadas, para mostrar alta eficiência e acurácia do método desenvolvido.This paper proposes a scheme of compact finite difference higher order for solve elliptic problems with variable coeficients in composite meshes. we present the mathematical formulation and the deduction of the compact method of fourth order applied to two-dimensional elliptic problems in regular and composite mesh . It was adopted using the PETSc library with its pre- conditioners and numerical methods for solving linear systems resulting from discretization of the problem. Finally , tests to verify the code were made using the method of manufactured solutions to show high eficiency and accuracy of the method developed .
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Bengtsson, Fred. „Värdering av minor för mekaniserad strid“. Thesis, Försvarshögskolan, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:fhs:diva-9898.
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Stridsvagnsminans utveckling i helhet har under de senaste 20 åren mer eller mindre stått still. I försvarsberedningens slutrapport Värnkraft beskrivs fördröjande fältarbeten med minor som ett av de prioriterade områdena för Försvarsmaktens ingenjörförband. Med denna prioritering finns ett syfte att undersöka hur vidare minor fortsatt kommer att påverka den mekaniserade striden i framtiden. För att studera minors påverkan på den mekaniserade striden har den här studien använt Totalförsvarets forskningsinstituts simuleringsverktyg Suss-mek. Minvapnet finns sedan tidigare inte implementerat i programmet. Därför undersöks också vilka nyckelegenskaper som bör ingå i simulering med minor i strid. Resultatet visar att effekten av framtidens minor på den mekaniserade striden kommer i grunden vara densamma som idag. Däremot kommer teknologin för framtidens minor göra att minan i sig kommer att bli effektivare med högre sannolikhet att nedkämpa motståndaren. Studien kommer också fram till flera relevanta nyckelegenskaper, till exempel front, djup, densitet och fasta beteenden vid sammanstötminering. Det är egenskaper som måste tas hänsyn till vid modellering av minor i ett simuleringsverktyg.The development of the antitank mine has more or less stood still for the past 20 years. In the Defense Committee's final report Värnkraft, counter-mobility operations with landmines is described as one of the priority areas for the Swedish Armed Forces' combat engineer units. With this priority, there is a purpose to investigate how mines will continue to affect the mechanized battle in the future. To study the impact of antitank mines on the mechanized battle, this study has used the Swedish Defense Research Agency's simulation tool Suss-mek. The mine weapon has not previously been implemented in the program. Therefore, it is also investigated which key characteristics that should be included in simulation with mines in battle. The results show that the impact of future antitank- mines in mechanized battle will basically be the same as today. On the other hand, the technology of the future mines will make the mine itself more efficient with a higher probability to kill. The study also shows several relevant key characteristics for example: front, depth, density and fixed behaviours during entering minefield. They are characteristics that must be considered when modelling mines in a simulation tool.
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Hocine, Farida. „Approximation spectrale d'opérateurs“. Saint-Etienne, 1993. http://www.theses.fr/1993STET4007.
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Il est bien connu que la convergence fortement stable est une condition suffisante de convergence des éléments spectraux approchées, i. E. Les valeurs propres non nulles, isolées et de multiplicité algébrique finie et les sous-espaces invariants maximaux qui leur sont associés, d'opérateurs linéaires bornés définis sur des espaces de Banach complexes. Dans ce travail, nous commençons par proposer une nouvelle notion de convergence : la convergence spectrale, que l'on montre être une condition nécessaire de convergence fortement stable et suffisante de convergence des éléments spectraux approchés. Nous donnons ensuite des conditions suffisantes de convergence spectrale moins restrictives que celles habituellement utilisées. Nous montrons également la convergence de quelques schémas de raffinement itératif pour l'approximation des bases de sous-espaces invariants maximaux, dans le cadre des méthodes de Newton inexactes et des séries de Rayleigh-Schrodinger, sous certaines des conditions suffisantes de convergence spectrale proposées. Nous donnons ensuite les résultats de quelques essais numériques
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Bouhaya, Lina. „Optimisation structurelle des gridshells“. Phd thesis, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00583409.
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Le terme gridshell désigne une coque discrète qui est obtenue par déformation élastique d'une grille bidirectionnelle continue plane sans rigidité en cisaillement puis rigidifiée par une troisième direction de barres. Ainsi défini, un gridshell a un potentiel structural intéressant et peut répondre à des exigences architecturales complexes. La recherche de forme de ces structures a été menée à travers l'histoire principalement par deux méthodes, la méthode du filet inversé et la relaxation dynamique. Ces deux méthodes permettent d'obtenir une forme approchée de celle proposée par l'architecte, dérivant d'une grille à plat et de conditions aux limites partiellement ou complètement imposées. Dans le cadre de cette thèse, nous nous sommes intéressés à générer un gridshell sur une surface à forme et contours imposés. Un outil numérique se basant sur la méthode du compas a été développé. Il permet de mailler un réseau de Tchebychev sur une surface connaissant son équation cartésienne. Un autre outil permettant le maillage se basant sur un calcul en éléments finis explicite a été mis en œuvre. La particularité de cette technique est de pouvoir tenir en compte des propriétés mécaniques de la structure et de simuler le comportement du gridshell. Des applications des deux méthodes sur des formes architecturalement intéressantes ont permis de voir les limitations de la possibilité de mailler une forme avec un réseau de Tchebychev. La méthode du compas a ensuite été couplée à des algorithmes métaheuristiques types génétiques. L'algorithme résultant permet d'optimiser un gridshell en minimisant la courbure dans les barres et donc les contraintes dans la structure introduites lors de la mise en forme. Il a été mis en œuvre et testé pour plusieurs surfaces
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Savioli, Rafael Guimarães. „Avaliação dos parâmetros CTOD e integral J em juntas soldadas utilizando corpos-de-prova compactos C(T)“. Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/3/3135/tde-28052012-171641/.
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Este trabalho visa o refinamento do procedimento para estimativa dos parâmetros elasto-plásticos de tenacidade à fratura, integral J e CTOD, incorporando o efeito de dissimilaridade mecânica devido à introdução de juntas soldadas utilizando a metodologia eta, tal efeito não é previsto na formulação das atuais normas de avaliação de tenacidade à fratura, porém a dissimilaridade mecânica afeta fortemente a relação entre o carregamento global do espécime e as forças motrizes na ponta da trinca. Para o desenvolvimento das análises foi empregada a geometria normalizada C(T), compacta, pois esta pode apresentar potencias vantagens sobre a geometria SE(B), flexão três pontos, como menor consumo de material para a confecção dos espécimes, menor capacidade do aparato experimental e fácil manipulação na prática dos testes laboratoriais, porém carece de fatores eta quando comparados ao tradicional espécime SE(B). Os principais objetivos deste trabalho são gerar um compêndio de fatores eta e propor uma formulação robusta que incorpore os efeitos de dissimilaridade mecânica para o cálculo de integral J e CTOD. Para tal intento a matriz de análise deste trabalho abrange diferentes comprimentos de trinca, níveis de dissimilaridade mecânica e larguras de cordão de solda, 0.45a/W0.6 e 1M y 1.3, 10 mm2h20 mm respectivamente. As análises numéricas foram realizadas nas condições de estado plano de deformação (2D) e tridimensional (incluindo o efeito acoplado entre os campos de tensões e deformações no plano e fora do plano), os resultados fornecem um bom suporte ao uso da geometria C(T) com trinca central no cordão de solda para avaliação de tenacidade à fratura em juntas soldadas de materiais comumente aplicados na construção de dutos e vasos de pressão.This work focuses on the evaluation procedure to determine the elastic-plastic J integral and CTOD fracture toughness based upon the eta-method for C(T) fracture specimens including overmatched weldments. Since fracture toughness test protocols do not address weld strength mismatch effect, this effect strongly alters the relationship between global loads and crack driving forces. The objectives of this investigation are to enlarge plastic eta-factor data base for C(T) specimen and to develop a robust formulation to address weld strength mismatch. The present analyses enable the introduction of a larger set of plastic eta-factors for a wide range of crack sizes (as measured by the a/W-ratio) and material properties, including different levels of weld strength mismatch, applicable to structural, pipeline and pressure vessel steels. Very detailed non-linear finite element analyses for plane-strain and full 3D models of standard C(T) fracture specimens provide the evolution of load with increased crack mouth opening displacement (and LLD) required for the estimation procedure. The results provide a strong support to use the plastic eta-factor in J integral and CTOD estimation procedures for center notch welded C(T) fracture specimen.
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Santos, Paulo Roberto Cunha dos. „S?ntese, sinteriza??o e caracteriza??o de ferrita de n?quel“. Universidade Federal do Rio Grande do Norte, 2014. http://repositorio.ufrn.br:8080/jspui/handle/123456789/18676.
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Previous issue date: 2014-05-27Universidade Federal do Rio Grande do Norte
In this work we obtain nickel ferrite by the combustion synthesis method whcih involves synthesising in an oven at temperatures of 750oC, 950oC and 125oC. The precursors oxidizing used were nickel nitrate, ferric as an oxidizing and reducing urea (fuel). After obtaining the mixture, the product was deagglomerated and past through a 270 mesh sieve. To assess the structure, morphology, particle size, magnetic and electrical properties of nanoparticles obtained the samples were sintered and characterized by x-ray distraction (XRD), x-ray fluorescence spectroscopy (FRX); scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), vibrating sample magnetometer (MAV ) and electrical permittivity. The results indicated the majority of phase inverse spinel ferrite and Hematite secondary phase nickel and nickel oxide. Through the intensity of the distraction, the average size of the crystallization peaks were half-height width which was calculated using the Scherrer equation. From observing the peaks of all the reflections, it appears that samples are crystal clear with the formation of nanoparticles. Morphologically, the nanoferritas sintered nickel pellet formation was observed with three systems of particle size below 100mn, which favored the formation of soft pellets. The average size of the grains in their micrometric scale. FRX and EDS showed qualitatively the presence of iron elements nickel and oxygen, where through quantitative data we can observe the presence of the secondary phase. The magnetic properties and the saturation magnetization and the coercive field are in accordance with the nickel, ferrite where the curve of hysteresis has aspects of a soft material. Dielectric constant values are below 10 and low tangent loss
Este trabalho descreve a obten??o de ferrita de n?quel pelo m?todo de s?ntese de combust?o, seguida pela sinteriza??o em forno, ?s temperatura de 750oC, 950oC e 1250oC. Os precursores oxidantes utilizados foram: nitratos de n?quel e ferro III como redutor, foi usada a ur?ia (combust?vel). Depois da obten??o do p?s-misturas, o produto foi desaglomerado e passado em uma peneira de mesch 270. A estrutura, a morfologia, o tamanho das part?culas e as propriedades magn?ticas e el?tricas das nanopart ?culas obtidas das amostras p?s sinterizadas foram caracterizadas por difra??o de raios-X (DRX), espectroscopia de uoresc?ncia de raios-X (FRX), microscopia eletr?nica de varredura (MEV ), espectroscopia de energia dispersiva (EDS), magnet ?metro de amostra vibrante (MAV ) e an?lise el?trica. Os resultados indicaram a fase majorit?ria do espin?lio inverso ferrita de n?quel e a fase secund?ria de hematita e ?xido de n?quel. Atrav?s da intensidade dos picos de difra??o de raios-X e da largura de meia altura no espectro, foi calculado o tamanho m?dio do cristalito pela equa??o Scherrer, observando-se os picos de todas as re ex?es, veri cando a cristalinidade das amostras, e com forma??o de nanopart?culas. Morfologicamente, para as nanoferritas de n?quel sinterizadas, observou-se a forma??o de aglomerados moles nos tr?s sistemas com part?culas de tamanho inferior a 100nm. O tamanho m?dio dos gr?os est? em escala microm?trica. Os espectros de FRX e EDS mostraram qualitativamente a presen?a dos elementos ferro, n?quel e oxig?nio. Atrav?s dos dados quantitativos, pode-se observar a presen?a da fase secund?ria. As propriedades magn?ticas, como a magnetiza??o de satura??o e o campo coercitivo, est?o de acordo com a ferrita de n?quel, em que a curva de histerese tem aspectos de um material mole. Os valores de constante diel?trica est?o abaixo de 10 e baixa tangente de perdas.
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Reis, Gabriela Aparecida dos. „Estudo de métodos de interface imersa para as equações de Navier-Stokes“. Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-12122016-154218/.
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Uma grande limitação dos métodos de diferenças finitas é que eles estão restritos a malhas e domínios retangulares. Para descrever escoamentos em domínios complexos, como, por exemplo, problemas com superfícies livres, faz-se necessário o uso de técnicas acessórias. O método de interfaces imersas é uma dessas técnicas. Nesse trabalho, primeiramente foi desenvolvido um método de projeção, totalmente livre de pressão, para as equações de Navier-Stokes com variáveis primitivas em malha deslocada. Esse método é baseado em diferenças finitas compactas, possuindo segunda ordem temporal e quarta ordem espacial. Esse método foi combinado com o método de interface imersa de Linnick e Fasel [2] para resolver numericamente as equações de Stokes com quarta ordem de precisão. A verificação do código foi feita por meio do método das soluções manufaturadas e da comparação com resultados de outros autores em problemas clássicos da literatura.A great limitation of finite differences methods is that they are restricted to retangular meshes and domains. In order to describe flows in complex domains, e.g. free surface problems, it is necessary to use accessory techniques. The immersed interface method is one of such techniques. In the present work, firstly, a projection method was developed, which is completely pressure-free, for the Navier-Stokes equations with primitive variables in a staggered mesh. This method is based on compact finite differences, with temporal second-order precision and spatial foruth-order precision. This method was combined with the immersed interface method from Linnick e Fasel [2] in order to numerically solve the Stokes equations with fourth-order precision. The verification of the code was performed with the manufactured solutions method and by comparing results with other authors for some classical problems in the literature.
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Lu, Chunmeng. „Development of novel micro-embossing methods and microfluidic designs for biomedical applications“. Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1156820643.
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Roussafi, Abdellah. „Modélisation compacte du rayonnement d'antennes ULB en champ proche/champ lointain : mise en application en présence d'interface“. Thesis, Université Côte d'Azur (ComUE), 2016. http://www.theses.fr/2016AZUR4137/document.
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Les performances des antennes Ultra Large Bande (ULB) les rendent appropriées pour de nombreuses applications. En radar à pénétration de surface (SPR), application visée de cette thèse, une telle bande passante offre un excellent compromis entre capacité de pénétration et résolution spatiale en imagerie micro-ondes. De plus, il a été démontré que la prise en compte du champ rayonné par l'antenne en présence de la surface améliore considérablement la qualité des images obtenues. Cette thèse aborde la problématique de la quantité de données représentant les antennes ULB. En effet, les descripteurs classiques d'antenne ne suffisent pas à caractériser l’évolution en fréquence de leurs performances. Le développement en harmoniques ou vecteurs sphériques est utilisé pour modéliser le diagramme de rayonnement d’antennes tout en réduisant le volume de données. D'autre part, les méthodes d'expansion en singularités modélisent la réponse en fréquence (ou impulsionnelle) de l'antenne par un ensemble de pôles de résonance. Le but de ce travail de thèse est d'établir un modèle compact qui représente avec précision le rayonnement d'antenne, et permette la connaissance du champ à différentes distances. A cette fin, plusieurs combinaisons des méthodes de caractérisation ont été étudiées. L'approche proposée est validée par la modélisation du diagramme de rayonnement simulé et mesuré d'une antenne Vivaldi (ETSA). Le modèle établi fournit le champ rayonné à différentes distances de l'antenne avec une erreur inférieure à 3% avec un taux de compression de 99%. La dernière partie de cette thèse présente une application de l'approche proposée au rayonnement d’antennes en présence d’interfacesUWB antennas bandwidth makes them highly suitable for a number of applications. In surface penetrating radar (SPR) applications, which is the focus of our research, such a bandwidth range allows good signal penetration ability and fine space resolution for microwave imaging. In addition, it has been shown that the knowledge of the radiated field by the antenna enhances drastically the quality of the resulting images. The work reported in this thesis deals with the problematic of the huge amount of data representing UWB antennas. Indeed, due to the frequency dependence, the classical antenna parameters are not sufficient to characterize this type of antenna. The scalar or vector spherical wave expansion is widely used to expand the radiation pattern of a radiating antenna and permit a high compression data rate. On the other hand, the Singularity Expansion Methods are used in frequency/time domain to model the antenna response by a set of resonant poles. The purpose of this thesis is to establish a compact model representing accurately the antenna radiation characteristics, which also allows to find the field at various distances. To this end, several ways of combining the aforementioned methods have been investigated. The proposed approach is validated by modeling the simulated and measured radiation pattern of an Exponential Tapered Slot Antenna (ETSA) in free space. Furthermore, we verify that the established compact model provide radiated field at different distances from the antenna with a compression of the initial pattern up to 99% and an error below 3%. The last part of this thesis, present an application of the proposed methodology to SPR context
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Omar, hoch Souleiman. „Study of compact quantum groups with probabilistic methods : caracterization of ergodic actions and quantum analogue of Noether's isomorphisms theorems“. Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCD014/document.
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Cette thèse étudie des problèmes liés aux treillis des sous-groupes quantiques et la caractérisationdes actions ergodiques et des états idempotents d’un groupe quantique compact.Elle consiste en 3 parties. La première partie présente des résultats préliminaires sur lesgroupes quantiques localement compacts, les sous-groupes quantiques normaux ainsi queles actions ergodiques et les états idempotents. La seconde partie étudie l’analogue quantiquede la règle de modularité de Dedekind et de l’analogue quantique des théorèmesd’isomorphisme de Noether ainsi que leur conséquences comme le théorème de raffinementde Schreier, et le théorème Jordan-Hölder. Cette partie s’inspire du travail de recherche deShuzhouWang sur l’analogue quantique du troisième théorème d’isomorphisme de Noetherpour les groupes quantiques compacts ainsi que le travail récent de Kasprzak, Khosraviet Soltan sur l’analogue quantique du premier théorème d’isomorphisme de Noether pourles groupes quantiques localement compacts. Dans la troisième partie, nous caractérisonsles états idempotents du groupe quantique compact O−1(2) en s’appuyant sur la caractérisationde ses actions ergodiques plongeables. Cette troisième partie est dans la lignedes travaux fait par Franz, Skalski et Tomatsu pour les groupes quantiques compactsUq(2), SUq(2) et SOq(3). Nous classifions au préalable les actions ergodiques et les actionsergodiques plongeables du groupe quantique compact O−1(2).Les travaux présentés dans cette thèse se basent sur deux articles de l’auteur et al.Le premier s’intitule “Fundamental isomorphism theorems for quantum groups” et a étéaccepté pour publication dans Expositionae Mathematicae et le second est intitulé “Ergodicactions and idempotent states of O−1(2)” et est en cours de finalisation pour être soumisThis thesis studies problems linked to the lattice of quantum subgroups and characterizationof ergodic actions and idempotent states of a compact quantum group. It consistsof three parts. The first part present some preliminary results about locally compactquantum groups, normal quantum subgroups, ergodic actions and idempotent states. Thesecond part studies the quantum analog of Dedekind’s modularity law, Noether’s isomorphismtheorem and their consequences as the Schreier refinement theorem and theJordan-Hölder theorem. This part completes the work of Shuzhou WANG on the quantumanalog of the third isomorphism theorem for compact quantum group and the recentwork of Kasprzak, Khosravi and Soltan on the quantum analog of the first Noether isomorphismtheorem for locally compact quantum groups. In the third part, we characterizeidempotent states of the compact quantum group O−1(2) relying on the characterizationof embeddable ergodic actions. This third part is in the sequence of the seminal works ofFranz, Skalski and Tomatsu for the compact quantum groups Uq(2), SUq(2) and SOq(3).We classify in advance the ergodic actions and embeddable ergodic actions of the compactquantum group O−1(2).This thesis is based on two papers of the author and al. The first one is entitled“Fundamental isomorphism theorems for quantum groups” which have been accepted forpublication in Expositionae Mathematicae and the second one is entitled “Ergodic actionsand idempotent states of O−1(2)” and is being finalized for submission
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Rogenski, Josuel Kruppa. „Desenvolvimento e otimização de um código paralelizado para simulação de escoamentos incompressíveis“. Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-12052011-145111/.
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O presente trabalho de pesquisa tem por objetivo estudar a paralelização de algoritmos voltados à solução de equações diferenciais parciais. Esses algoritmos são utilizados para gerar a solução numérica das equações de Navier-Stokes em um escoamento bidimensional incompressível de um fluido newtoniano. As derivadas espaciais são calculadas através de um método de diferenças finitas compactas com a utilização de aproximações de altas ordens de precisão. Uma vez que o cálculo de derivadas espaciais com alta ordem de precisão da forma compacta adotado no presente estudo requer a solução de sistemas lineares tridiagonais, é importante realizar estudos voltados a resolução desses sistemas, para se obter uma boa performance. Ressalta-se ainda que a solução de sistemas lineares também faz-se presente na solução numérica da equação de Poisson. Os resultados obtidos decorrentes da solução das equações diferenciais parciais são comparados com os resultados onde se conhece a solução analítica, de forma a verificar a precisão dos métodos implementados. Os resultados do código voltado à resolução das equações de Navier-Stokes paralelizado para simulação de escoamentos incompressíveis são comparados com resultados da teoria de estabilidade linear, para validação do código final. Verifica-se a performance e o speedup do código em questão, comparando-se o tempo total gasto em função do número de elementos de processamento utilizadosThe objective of the present work is to study the parallelization of partial differential equations. The aim is to achieve an effective parallelization to generate numerical solution of Navier-Stokes equations in a two-dimensional incompressible and isothermal flow of a Newtonian fluid. The spatial derivatives are calculated using compact finite differences approximations of higher order accuracy. Since the calculation of spatial derivatives with high order adopted in the present work requires the solution of tridiagonal systems, it is important to conduct studies to solve these systems and achieve good performance. In addiction, linear systems solution is also present in the numerical solution of a Poisson equation. The results generated by the solution of partial differential equations are compared to analytical solution, in order to verify the accuracy of the implemented methods. The numerical parallel solution of a Navier-Stokes equations is compared with linear stability theory to validate the final code. The performance and the speedup of the code in question is also checked, comparing the execution time in function of the number of processing elements
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Lima, Andr?ia Cavalcante de. „S?ntese, caracteriza??o e estudo das propriedades magn?ticas de ortoferritas de lant?nio dopadas com mangan?s“. Universidade Federal do Rio Grande do Norte, 2010. http://repositorio.ufrn.br:8080/jspui/handle/123456789/17748.
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Orthoferrites AFeO3 (A = rare earth) are an important class of perovskite oxides that exhibit weak ferromagnetism. These materials find numerous applications as chemical sensors, cathodes for fuel cells and catalysis, which make them interesting from the standpoint of science and technology. Their structural, electrical and magnetic properties are dependent on many factors such as the preparation method, heat treatment conditions, chemical composition and replacement of cations in sites A and/or B. In this paper, LaFe1-xMnxO3 (0 ≤ x ≤ 1) orthoferrites-type was prepared by Pechini method and Microwave-assisted combustion reaction in order to evaluate the influence of synthesis route on the formation of oxide, as well as the effect of parcial replacement of iron by manganese and heat treatment on the magnetic properties. The precursor powders were calcined at 700?C, 900?C, 1100?C and 1300?C for 4 hours and they were characterized by the techniques: Thermogravimetric analysis (TGA), X ray diffraction (XRD), Refinement by Rietveld method, Scanning electron microscopy (SEM), Reduction temperature programmed (RTP) and Magnetic hysteresis measurements performed at room temperature. According to the XRD patterns, the formation of perovskite phase with orthorhombic structure was observed for the systems where 0 ≤ x ≤ 0.5 and rhombohedral for x = 1. The results also showed a decrease of lattice parameters with the parcial replacement of iron by manganese and consequently a reduction in cell volume. The hysteresis curves exhibited weak ferromagnetism for the systems prepared by both synthesis methods. However, a dependence of magnetization as a function of dopant content was observed for samples produced by Pechini method. As for the systems prepared by combustion reaction, it was found that the secondary phases exert a strong influence on the magnetic behavior
Ortoferritas AFeO3 (A = terra rara) constituem uma importante classe de ?xidos perovskita que exibem ferromagnetismo fraco. Estes materiais encontram in?meras aplica??es como sensores qu?micos, catodos para c?lulas a combust?veis e na ?rea de cat?lise, o que os fazem interessantes do ponto de vista cient?fico e tecnol?gico. Suas propriedades estruturais, el?tricas e magn?ticas s?o dependentes de v?rios fatores tais como: o m?todo de prepara??o, condi??es do tratamento t?rmico, composi??o qu?mica e substitui??o de c?tions nos s?tios A e/ou B. Neste trabalho, ortoferritas do tipo LaFe1-xMnxO3 (0 ≤ x ≤ 1) foram preparadas pelo m?todo Pechini e pela rea??o de combust?o assistida por microondas com a finalidade de avaliar a influ?ncia da rota de s?ntese na forma??o do ?xido, assim como o efeito da substitui??o parcial do ferro por mangan?s e do tratamento t?rmico nas propriedades magn?ticas. Os p?s precursores foram calcinados a 700?C, 900?C, 1100?C e 1300?C por 4 horas e caracterizados atrav?s das t?cnicas: An?lise termogravim?trica (TG), Difra??o de raios X (DRX), Refinamento pelo m?todo de Rietveld, Microscopia eletr?nica de varredura (MEV), Redu??o a temperatura programada (RTP) e Medidas de histerese magn?ticas realizadas ? temperatura ambiente. De acordo com os difratogramas, a forma??o da fase perovskita com estrutura ortorr?mbica foi observada para os sistemas onde 0 ≤ x ≤ 0,5 e, rombo?drica para x = 1. Os resultados tamb?m mostraram uma diminui??o dos par?metros de rede com a substitui??o parcial do ferro por mangan?s e, conseq?entemente uma redu??o do volume da c?lula unit?ria. As curvas de histerese exibiram ferromagnetismo fraco para os sistemas preparados por ambos os m?todos de s?ntese. Entretanto, uma depend?ncia da magnetiza??o em fun??o do teor de dopante foi observada para as amostras produzidas pelo m?todo Pechini. J? para os sistemas preparados por rea??o de combust?o, verificou-se que as fases secund?rias exercem forte influ?ncia no comportamento magn?tico
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Hoffmann, Júlio Cury. „Avaliação de métodos para estimativas de dissimilaridade em gradientes ecológicos com alta diversidade beta“. Universidade Federal de Goiás, 2018. http://repositorio.bc.ufg.br/tede/handle/tede/8649.
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There are several problems on the analysis of biological communities with sparse data, resulting from gradients with high beta diversity. I used four strategies to solve this problem (Beals smoothing, Swan, Shortest Path and Extended Dissimilarity). I randomly removed from 1% to 50% of the individuals in empirical and simulated matrices. I then performed PCoA and nMDS ordinations and used Procrustes correlation of the original two dimensional ordination with the ordination obtained using the degraded matrices. For the simulated data set, I also correlated the ordenation in two dimensions with the coordinates of the samples in the two-dimensional simulated gradients. Finally, I analyzed how robustness to degradation, quantified as Procrustean correlation, was related to the matrix properties. Different from the expected, in the comparison of the degraded and original ordinations, the uncorrected data with a traditional dissimilarity index (Bray-Curtis) produced higher fit than the four methods evaluated. In relation to the coordinates of the simulated two-dimensional gradients, the evaluated methods were slightly better than the raw data. Overall, the simulated data were more robust to the degradation than the empirical ones and the data of abundance were more robust than matrices of presence and absence. Matrices with small proportion of zeros were more robust to degradation. I conclude that the correction methods evaluated distorted the pattern on the original data. Also, data with low beta diversity (few zeros) are robust to degradation and sufficient to reconstruct the original gradient.
Existem vários problemas nas análises de comunidades em Ecologia decorrentes da grande quantidade de zeros na matriz de espécies por locais (dados esparsos), principalmente em situações em que a diversidade beta é alta. Usando quatro estratégias para resolver estes problemas (Beals, Swan, Menor Caminho e Dissimilaridade estendida) retirei aleatoriamente de 1 ate 50 % dos indivíduos de matrizes empíricas e simuladas (degradação das matizes). Realizei ordenações PCoA e nMDS e, com correlações de Procrustes, relacionei a ordenação original em duas dimensões com a ordenação obtida pelas matrizes degradadas. Com dados simulados relacionei a ordenação em duas dimensões também com as coordenadas das amostras no gradiente bidimensional simulado. Além disso, analisei como a robustez à degradação, medida como correlação Procrustes, está relacionada às características da matriz. Diferente do esperado, na comparação das ordenações de matrizes degradadas com a ordenação da matriz original, os dados utilizados sem correções e com índice de dissimilaridade tradicional (Bray-Curtis) tiveram maior ajuste que os quatro métodos avaliados. Em relação às coordenadas, os métodos aplicados tiveram desempenho um pouco melhor do que os dados sem correções quando a diversidade beta foi maior. Em geral, os dados simulados foram mais robustos à degradação que os empíricos e os dados de abundância foram mais robustos que de presença e ausência. Matrizes com menor proporção de zeros foram mais robustas à degradação. Concluo que os métodos de correção distorceram o padrão dos dados originais. Ainda, dados com baixa diversidade beta (poucos zeros na matrix) são robustos à degradação e são suficientes para reconstruir o gradiente original.
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Jardim, Maurício Ferreira [UNESP]. „Análise teórica e experimental vibro-acústica utilizando a técnica de matrizes compactas“. Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/94549.
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Em muitos problemas do nosso cotidiano ocorre acoplamento entre a resposta acústica no interior de uma cavidade e a excitação estrutural em um de seus contornos flexíveis, bem como a resposta estrutural nestes contornos também está relacionada à fonte acústica da cavidade. Interior de automóveis, cabine de caminhões e fuselagem de aviões são apenas alguns exemplos práticos destes tipos de sistemas. Acoplamento implica que o comportamento dos sistemas acústico e estrutural não são independentes um do outro, e ambos devem ser considerados como um único sistema global. O propósito deste trabalho é avaliar a técnica de matrizes compactas na solução de problema de acoplamento vibroacústico em cavidades de geometria regular e irregular. Preliminarmente, a análise do acoplamento vibro-acústico é baseado no método dos elementos finitos e o conjunto de equações não simétricas que modela o movimento é discutida. A aproximação vibro-acústica por matrizes compactas é feita utilizando conceitos de impedância e mobilidade. No modelo de matrizes compactas, o acoplamento é obtido através da avaliação dos modos acústicos e estruturais desacoplados da cavidade e da estrutura flexível, respectivamente. Simulações numéricas utilizando o método dos elementos finitos e a técnica de matrizes compactas são apresentadas para modelos vibro-acústicos de geometria regular e irregular. Testes experimentais são realizados em uma cavidade irregular feita de PVC e aço. A metodologia de análise dos resultados é baseada nas FRF(s) definidas pelas relações entre a resposta em pressão acústica da cavidade e a força estrutural e entre a resposta em velocidade e a força estrutural aplicada sobre a superfície flexível. A comparação dos modelos numéricos e experimentais mostra o potencial da técnica de matrizes compactas.
In many systems of day-life occurs the coupling between the acoustical response in a cavity and a structural excitation on a flexible boundary, whereas the structural response in this same boundary is also related to acoustical excitation source. Car interiors, cabs of trucks and aircraft fuselage are a just a few practical examples of this sort of systems. Coupling implies that the acoustical and structural system behavior is not independent from each other, and therefore they must be considered as a global system behavior. The aim of this work is to evaluate a compact matrix formulation to solve vibro-acoustic problems in regular and irregular shape cavity. Preliminary, the vibro-acoustic coupling analysis is based on finite element method and the set of non-symmetric equation that represents the movement is discussed. The compact matrix formulation approaches have been done using impedance and mobility concepts. In compact matrix model, the coupling is obtained by evaluating the uncoupled acoustic modes and structural modes of the cavity and flexible structure, respectively. Numerical simulation using the finite element method and the compact matrix formulation are shown for regular and irregular shape cavity model. Experimental tests are evaluated in an irregular rigid cavity made of PVC and steel. The results analysis methodology is based on FRF(s) defined by the relationship between the pressure acoustic response in the cavity and structural force and between the velocity response and structural force applied on the flexible boundary. The comparison of numerical and experimental models shows the potential of the compact matrix formulation.
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Silva, Filho Elson Borges da [UNESP]. „Estudo de campo elétrico em linha de transmissão utilizando o método dos elementos de contorno“. Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/87237.
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Este trabalho analisa a aplicação em linhas de transmissão do método dos elementos de contorno para cálculo de potencial e campo elétrico, com um enfoque em eletrostática. O método dos elementos de contorno baseia-se numa formulação integral que elimina a discretização do domínio, restando apenas o contorno, permitindo o cálculo do potencial e do campo elétrico no contorno e na região estudada. O trabalho configura-se como uma revisão sobre eletrostática, ressaltando as equações de Laplace e Poisson, que serão utilizadas para encontrar as equações integrais do contorno. Há também vários tópicos relacionados ao campo elétrico de linhas de transmissão, bem como, ás normas brasileiras e recomendações internacionais que devem ser utilizadas no projeto de linhas de transmissão. O método dos elementos de contorno utiliza tais equações integrais para encontrar o potencial e o campo no contorno, e após conhecidos o potencial e o campo no contorno, pode-se aplicar o método em todo o domínio, obtendo o potencial e o campo. Para isso, apenas o contorno do domínio de interesse deve ser discretizado, o que trás uma enorme vantagem sobre os métodos que utilizam formulação diferencial. Neste trabalho, serão descritas as principais características do código computacional desenvolvido e suas sub-rotinas mais importantes. Para validar o programa, os resultados serão comparados com aqueles calculados por um procedimento analítico, sendo mostrada a eficiência da discretização do solo. São apresentados os resultados obtidos da análise do campo elétrico gerado por algumas silhuetas de linhas de transmissão. Os valores do campo elétrico gerado por estruturas compactas são comparados com estruturas convencionais e estruturas reduzidas (semi-compactas), também serão comparados os valores do gradiente de potencial na superfície dos condutores e suas capacitâncias equivalentes.
This paper analyses the application in transmission lines of the Boundary Element Method (BEM) of the calculation of potential and electric field, with a focus on electrostatic. The Boundary Element Method is based on an integral formulation that eliminates the discretisation of the domain, remaining only the contour, allowing the calculation of the potential and the electric field in the contour and in the region studied. The work is configured as revision on electrostatic, underscoring the equations of Laplace and Poisson, which will be used to find the integral equations of the contour. There are also several topics related to the electric field of transmission lines, as well as to the standards Brazilian and international recommendations to be used in the design of transmission lines. The Boundary Element Method uses such integral equations for finding the potential and electric field in the contour, and after having known the potential and electric field in the contour, the BEM can be applied in the whole domain, and getting the potential and electric field. Therefore, only the contours of the domain of interest should just be discretized, which backward an enormous advantage on the methods that use formulation differential. This paper will describe the main characteristics of computer code developed and their sub-routines more important. To validate the program, the results will be compared with those calculated by an analytic procedure, being shown the efficiency of discretisation of the soil. The results obtained from analysis of the electric field generated by some silhouettes of transmission lines are presented. The values of the electric field generated by compact structures are compared with conventional structures and reduced structures, also will be compared the values of the gradient of potential on the surface of the conductors and their equivalents capacitances.
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Znidarcic, Anton. „Un nouvel algoritme pour la simulation DNS et LES des ecoulements cavitants“. Thesis, Paris, ENSAM, 2016. http://www.theses.fr/2016ENAM0056/document.
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Le couplage diphasique-turbulence est une propriété clé des écoulements cavitants, qui est un frein important à l’amélioration des modèles de cavitation et de turbulence. Réaliser des simulations directes (DNS) est le moyen proposé ici pour s’affranchir du modèle de turbulence et obtenir des informations nouvelles sur les phénomènes mis en jeu. Ce type de simulation est exigeant sur le plan numérique, et requiert le développement d’un solveur spécifique intégrant les spécificités des modèles de cavitation. Cela inclue notamment des schémas de discrétisation d’ordre élevé, un solveur direct, et une résolution multi-domaines associée à une parrallélisation efficace. Une discrétisation par différences compactes finies s’avère être le meilleur choix. La contrainte de rapidité et de parrallélisation impose un algorithme où les systèmes résoudre n’impliquent des multiplications des variables implicites que par des coefficients invariants au cours du calcul. Un nouvel algorithme réunissant ces critères a été développé durant cette thèse, à partir de la combinaison de la méthode de Concus & Golub et d’une méthode de projection, qui permet de résoudre les équations associées à la modélisation homogène de la cavitation. Une nouvelle approche de vérification de ce nouvel algorithme est également proposée et mise en œuvre sur la base de la méthode des solutions manufacturées (MMS)Cavitation-turbulence interactions are problematic aspect of cavitating flows which imposes limitations in development of better cavitation and turbulence models. DNS simulations with homogeneous mixture approach are proposed to overcome this and offer more insight into the phenomena. As DNS simulations are highly demanding and a variety of cavitation models exists, a tool devoted specifically to them is needed. Such tools usually demand application of highly accurate discretization schemes, direct solvers and multi domain methods enabling good scaling of the codes. As typical cavitating flow geometries impose limits on suitable discretization methods, compact finite differences offer the most appropriate discretization tool. The need for fast solvers and good code scalability leads to request for an algorithm, capable of stable and accurate cavitating flow simulations where solved systems feature multiplication of implicitly treated variables only by constant coefficients. A novel algorithm with such ability was developed in the scope of this work using Concus and Golub method introduced into projection methods, through which the governing equations for homogeneous mixture modeling of cavitating flows can be resolved. Work also proposes an effective and new approach for verification of the new and existing algorithms on the basis of Method of Manufactured Solutions
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Larsson, David. „Algorithmic Construction of Fundamental Polygons for Certain Fuchsian Groups“. Thesis, Linköpings universitet, Matematik och tillämpad matematik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-119916.
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The work of mathematical giants, such as Lobachevsky, Gauss, Riemann, Klein and Poincaré, to name a few, lies at the foundation of the study of the highly structured Riemann surfaces, which allow definition of holomorphic maps, corresponding to analytic maps in the theory of complex analysis. A topological result of Poincaré states that every path-connected Riemann surface can be realised by a construction of identifying congruent points in the complex plane, the Riemann sphere or the hyperbolic plane; just three simply connected surfaces that cover the underlying Riemann surface. This requires the discontinuous action of a discrete subgroup of the automorphisms of the corresponding space. In the hyperbolic plane, which is the richest source for Riemann surfaces, these groups are called Fuchsian, and there are several ways to study the action of such groups geometrically by computing fundamental domains. What is accomplished in this thesis is a combination of the methods found by Reidemeister & Schreier, Singerman and Voight, and thus provides a unified way of finding Dirichlet domains for subgroups of cofinite groups with a given index. Several examples are considered in-depth.