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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
231

Le chasseur inconnu : suivi de Enjeux et effets de la narration au nous dans Une rose pour Emily de William Faulkner / Enjeux et effets de la narration au nous dans Une rose pour Emily de William Faulkner

Fortier, Jean-Michel 19 April 2018 (has links)
Le projet de création Le chasseur inconnu est un roman dont la narration problématique – au nous – constitue la principale particularité. Campé dans un village non identifié dont les habitants se réunissent chaque semaine pour débattre de leurs problèmes et pour potiner, ce texte de fiction se déploie grâce aux voix de narrateurs mystérieux et à leur ton parfois aux limites de l’absurde. L’essai réflexif qui suit le roman propose une étude des enjeux et des effets de la narration au nous dans la nouvelle Une rose pour Emily de William Faulkner. / The novel Le chasseur inconnu’s most defining characteristic is its narration ;  an unnatural we narration. The story takes place in an unknown town where villagers meet every week to discuss their problems and to gossip. As the plot unfolds, the mysterious narrators and their absurd voices become increasingly important and stress the narrative peculiarity of the novel. The essay following Le chasseur inconnu offers a study of we narration in William Faulkner’s short story A Rose for Emily.
232

Comportamento complexo em centros geradores de padrões / Complex behavior in central pattern generators

Reyes, Marcelo Bussotti 22 September 2005 (has links)
Realizamos simulações computacionais de modelos da atividade elétrica de centros geradores de padrões para investigar o fato experimental de organismos vivos utilizarem neurônios caóticos para produzir padrões periódicos. Centros geradores de padrões biológicos produzem atividades motoras periódicas que devem ser robustas a pequenas flutuações das propriedades dos neurônios e sinapses, mas também flexíveis para permitir a neuromodulação do ritmo. Utilizamos principalmente dois modelos de atividade neural, um modelo fenomenológico do tipo Hindmarsh-Rose e um modelo baseado em condutâncias do tipo Hodgking-Huxley. Realizamos também experimentos com redes híbridas, conectando dois tipos de neurônios do gânglio estomatogástrico de crustáceos aos neurônios modelo, que confirmaram os resultados obtidos nas simulações. Observamos o comportamento das redes principalmente em função de dois parâmetros: um que controla a atividade intrínseca dos neurônios e outro que representa a condutância máxima das sinapses químicas usadas para formar a rede. As redes apresentam atividade robusta e flexível quando os neurônios que as compõem apresentam comportamento intrínseco entre rajadas e tônico. Esta é a região onde os neurônios modelo apresentam comportamento caótico, o que é uma evidência do motivo de se observar este tipo de comportamento em neurônios isolados do gânglio estomatogástrico dos crustáceos. Mostramos que o modelo tipo Hodgkin-Huxley, apesar de mais realista do ponto de vista eletrofisiológico, não apresenta um comportamento coletivo satisfatório em termos de flexibilidade e robustez. Os experimentos com redes híbridas evidenciaram como deveria ser modificado o modelo para que o comportamento coletivo fosse restaurado. Investigamos também outros aspectos da atividade neural: a obtenção de padrões oscilatórios com neurônios que não apresentam comportamento intrinsecamente oscilatório e a influência de perturbações causada por ruídos na atividade neural. / Realizamos simulações computacionais de modelos da atividade elétrica de centros geradores de padrões para investigar o fato experimental de organismos vivos utilizarem neurônios caóticos para produzir padrões periódicos. Centros geradores de padrões biológicos produzem atividades motoras periódicas que devem ser robustas a pequenas flutuações das propriedades dos neurônios e sinapses, mas também flexíveis para permitir a neuromodulação do ritmo. Utilizamos principalmente dois modelos de atividade neural, um modelo fenomenológico do tipo Hindmarsh-Rose e um modelo baseado em condutâncias do tipo Hodgking-Huxley. Realizamos também experimentos com redes híbridas, conectando dois tipos de neurônios do gânglio estomatogástrico de crustáceos aos neurônios modelo, que confirmaram os resultados obtidos nas simulações. Observamos o comportamento das redes principalmente em função de dois parâmetros: um que controla a atividade intrínseca dos neurônios e outro que representa a condutância máxima das sinapses químicas usadas para formar a rede. As redes apresentam atividade robusta e flexível quando os neurônios que as compõem apresentam comportamento intrínseco entre rajadas e tônico. Esta é a região onde os neurônios modelo apresentam comportamento caótico, o que é uma evidência do motivo de se observar este tipo de comportamento em neurônios isolados do gânglio estomatogástrico dos crustáceos. Mostramos que o modelo tipo Hodgkin-Huxley, apesar de mais realista do ponto de vista eletrofisiológico, não apresenta um comportamento coletivo satisfatório em termos de flexibilidade e robustez. Os experimentos com redes híbridas evidenciaram como deveria ser modificado o modelo para que o comportamento coletivo fosse restaurado. Investigamos também outros aspectos da atividade neural: a obtenção de padrões oscilatórios com neurônios que não apresentam comportamento intrinsecamente oscilatório e a influência de perturbações causada por ruídos na atividade neural. We have performed computational simulations of models of the neural electrical activity of central pattern generators in order to investigate the experimental fact that living organisms use chaotic neurons to produce periodic patterns. Biological central pattern generators produce periodic motor activity that must be robust to small fluctuacions in the neural and synaptic properties, but they must also be flexible to alow rhythm neuromodulation. We have used mainly two different models of neural activity, one phenomenological Hindmarsh-Rose type and another conductance based Hodgking-Huxley type. We have also performed experiments with hybrid networks, connecting two types crustacean stomatogastric ganglion neurons with the model neurons, which confirmed the results obtained with the simulations. We have simulated the network behavior as a function of two parameters: the maximal conductance of the chemical synapses by which neurons are connected and a parameter that controls the intrinsic behavior of the neurons. The networks present robust and flexible activity when the neurons have intrinsic beharior between bursting and tonic. This is the region in which model neurons present chaotic behavior, what is an evidence of why chaotic behavior takes place in isolated neurons from the stomatogastric ganglion (STG) of crustaceans. We have shown that the Hodgking-Huxley type model does not perform a satisfactory collective behavior in terms of flexibility and robustness, in spite of its electrophysiological realism. Experiments with hybrid networks showed how the model should be modified in order to restore the proper collective behavior. We have also investigated other aspects of the neural activity: the observation of oscillatory patterns in networks composed by neurons that are not endogenous bursters and the influence of perturbations in the neural activity caused by noize.
233

Comportamento complexo em centros geradores de padrões / Complex behavior in central pattern generators

Marcelo Bussotti Reyes 22 September 2005 (has links)
Realizamos simulações computacionais de modelos da atividade elétrica de centros geradores de padrões para investigar o fato experimental de organismos vivos utilizarem neurônios caóticos para produzir padrões periódicos. Centros geradores de padrões biológicos produzem atividades motoras periódicas que devem ser robustas a pequenas flutuações das propriedades dos neurônios e sinapses, mas também flexíveis para permitir a neuromodulação do ritmo. Utilizamos principalmente dois modelos de atividade neural, um modelo fenomenológico do tipo Hindmarsh-Rose e um modelo baseado em condutâncias do tipo Hodgking-Huxley. Realizamos também experimentos com redes híbridas, conectando dois tipos de neurônios do gânglio estomatogástrico de crustáceos aos neurônios modelo, que confirmaram os resultados obtidos nas simulações. Observamos o comportamento das redes principalmente em função de dois parâmetros: um que controla a atividade intrínseca dos neurônios e outro que representa a condutância máxima das sinapses químicas usadas para formar a rede. As redes apresentam atividade robusta e flexível quando os neurônios que as compõem apresentam comportamento intrínseco entre rajadas e tônico. Esta é a região onde os neurônios modelo apresentam comportamento caótico, o que é uma evidência do motivo de se observar este tipo de comportamento em neurônios isolados do gânglio estomatogástrico dos crustáceos. Mostramos que o modelo tipo Hodgkin-Huxley, apesar de mais realista do ponto de vista eletrofisiológico, não apresenta um comportamento coletivo satisfatório em termos de flexibilidade e robustez. Os experimentos com redes híbridas evidenciaram como deveria ser modificado o modelo para que o comportamento coletivo fosse restaurado. Investigamos também outros aspectos da atividade neural: a obtenção de padrões oscilatórios com neurônios que não apresentam comportamento intrinsecamente oscilatório e a influência de perturbações causada por ruídos na atividade neural. / Realizamos simulações computacionais de modelos da atividade elétrica de centros geradores de padrões para investigar o fato experimental de organismos vivos utilizarem neurônios caóticos para produzir padrões periódicos. Centros geradores de padrões biológicos produzem atividades motoras periódicas que devem ser robustas a pequenas flutuações das propriedades dos neurônios e sinapses, mas também flexíveis para permitir a neuromodulação do ritmo. Utilizamos principalmente dois modelos de atividade neural, um modelo fenomenológico do tipo Hindmarsh-Rose e um modelo baseado em condutâncias do tipo Hodgking-Huxley. Realizamos também experimentos com redes híbridas, conectando dois tipos de neurônios do gânglio estomatogástrico de crustáceos aos neurônios modelo, que confirmaram os resultados obtidos nas simulações. Observamos o comportamento das redes principalmente em função de dois parâmetros: um que controla a atividade intrínseca dos neurônios e outro que representa a condutância máxima das sinapses químicas usadas para formar a rede. As redes apresentam atividade robusta e flexível quando os neurônios que as compõem apresentam comportamento intrínseco entre rajadas e tônico. Esta é a região onde os neurônios modelo apresentam comportamento caótico, o que é uma evidência do motivo de se observar este tipo de comportamento em neurônios isolados do gânglio estomatogástrico dos crustáceos. Mostramos que o modelo tipo Hodgkin-Huxley, apesar de mais realista do ponto de vista eletrofisiológico, não apresenta um comportamento coletivo satisfatório em termos de flexibilidade e robustez. Os experimentos com redes híbridas evidenciaram como deveria ser modificado o modelo para que o comportamento coletivo fosse restaurado. Investigamos também outros aspectos da atividade neural: a obtenção de padrões oscilatórios com neurônios que não apresentam comportamento intrinsecamente oscilatório e a influência de perturbações causada por ruídos na atividade neural. We have performed computational simulations of models of the neural electrical activity of central pattern generators in order to investigate the experimental fact that living organisms use chaotic neurons to produce periodic patterns. Biological central pattern generators produce periodic motor activity that must be robust to small fluctuacions in the neural and synaptic properties, but they must also be flexible to alow rhythm neuromodulation. We have used mainly two different models of neural activity, one phenomenological Hindmarsh-Rose type and another conductance based Hodgking-Huxley type. We have also performed experiments with hybrid networks, connecting two types crustacean stomatogastric ganglion neurons with the model neurons, which confirmed the results obtained with the simulations. We have simulated the network behavior as a function of two parameters: the maximal conductance of the chemical synapses by which neurons are connected and a parameter that controls the intrinsic behavior of the neurons. The networks present robust and flexible activity when the neurons have intrinsic beharior between bursting and tonic. This is the region in which model neurons present chaotic behavior, what is an evidence of why chaotic behavior takes place in isolated neurons from the stomatogastric ganglion (STG) of crustaceans. We have shown that the Hodgking-Huxley type model does not perform a satisfactory collective behavior in terms of flexibility and robustness, in spite of its electrophysiological realism. Experiments with hybrid networks showed how the model should be modified in order to restore the proper collective behavior. We have also investigated other aspects of the neural activity: the observation of oscillatory patterns in networks composed by neurons that are not endogenous bursters and the influence of perturbations in the neural activity caused by noize.
234

A Study on Comparison Websites in the Airline Industry and Using CART Methods to Determine Key Parameters in Flight Search Conversion / En studie av jämförelsehemsidor i flygbranschen och tillämpningen av CART metoder för att analysera nyckelparametrar i konvertering av flygsökningar.

Hansén, Jacob, Gustafsson, Axel January 2019 (has links)
This bachelor thesis in applied mathematics and industrial engineering and management aimed to identify relationships between search parameters in flight comparison search engines and the exit conversion rate, while also investigating how the emergence of such comparison search engines has impacted the airline industry. To identify such relationships, several classification models were employed in conjunction with several sampling methods to produce a predictive model using the program R. To investigate the impact of the emergence of comparison websites, Porter's 5 forces and a SWOT - analysis were employed to analyze findings of a literature study and a qualitative interview. The classification models developed performed poorly with regards to several assessments metrics which suggested that there were little to no significance in the relationship between the search parameters investigated and exit conversion rate. Porter's 5 forces and the SWOT-analysis suggested that the competitive landscape of the airline industry has become more competitive and that airlines which do not manage to adapt to this changing market environment will experience decreasing profitability. / Detta kandidatexamensarbete inriktat på tillämpad matematik och industriell ekonomi syftade till att identifiera samband mellan sökparametrar från flygsökmotorer och konverteringsgraden för utträde till ett flygbolags hemsida, och samtidigt undersöka hur uppkomsten av flygsökmotorer har påverkat flygindustrin för flygbolag. För att identifiera sådana samband, tillämpades flera klassificeringsmodeller tillsammans med stickprovsmetoder för att bygga en predikativ modell i programmet R. För att undersöka påverkan av flygsökmotorer tillämpades Porters 5 krafter och SWOT-analys som teoretiska ramverk för att analysera information uppsamlad genom en litteraturstudie och en intervju. Klassificeringsmodellerna som byggdes presterade undermåligt med avseende på flera utvärderingsmått, vilket antydde att det fanns lite eller inget samband mellan de undersökta sökparametrarna och konverteringsgraden för utträde. Porters 5 krafter och SWOT-analysen visade att flygindustrin hade blivit mer konkurrensutsatt och att flygbolag som inte lyckas anpassa sig efter en omgivning i ändring kommer att uppleva minskande lönsamhet.
235

Heterogeneity of Ohio’s Saline Reservoirs: Feldspar Abundance and its Effects on Carbon Sequestration

Dalton, Terra Ann 19 October 2011 (has links)
No description available.
236

A study of local color in New England short stories written between 1860 and 1900 by Harriet Beacher Stowe, Rose Terry Cooke, Sarah Orne Jewett, Mary Wilkins Freeman and Alice Brown

Howard, Lois Elda. January 1938 (has links)
Call number: LD2668 .T4 1938 H63
237

揭開奧修「神秘玫瑰」的神秘面紗--透過我的生命經驗來看見 / Uncovering the veil of Osho Mystic Rose activity--A Narrative Approach

吳浩平, Wu,Hau Ping Unknown Date (has links)
本研究以自我參與、自我敘說的方式,呈現超個人心理治療中的奧修「神秘玫瑰」活動,對研究者本身帶來何種的生命經驗?而此經驗又對研究者產生何種影響? 透過自我敘說的研究取向,研究者感受到整個活動過程,就像是從「頭」到「心」的療癒—一步一步地展現出研究者的人際關係、欲望、人格特質、身心狀況,並慢慢地開始化解掉身、心的不舒服,而產生人際模式、行為的改變,也幫助研究者領悟到助人工作的原動力。除此之外,透過活動過程的臉部紀錄,研究者也看到自己較深的內在情緒狀態。 而在故事敘說後的分析中,研究者發現自己小時候的經驗,影響到目前的人際關係與工作、生活態度,並在活動中得到轉化,而產生了具體的改變。除此之外,在整體生命能量上,也產生流動或提昇,並體會到自我生命的富足,是助人工作的原點。 在反思的部份,區分成活動參與者與論文研究者,兩個不同的層次。在參與者部份,我發現自己的生命,其實是一直在對抗主流的心理學、精神醫學,以表達精神障礙者家人的不滿,卻忘了把這股力量,轉成正向的力量,來照顧好自己。在研究者部份,發現要透過語言傳達自己的經驗,其實是一件不容易的事,並看到東方智慧運用在助人工作的可行性。 在建議的部份,再依據本研究的結果,提出帶領類似「神秘玫瑰」活動的超個人心理治療團體,所需注意的事。 最後,在「對話」的部份,呈現出研究者參與不同靈修活動的經驗,與經驗間的對話;並透過「現在的我」來看到,活動心得領悟是對參與者的當下有益,而提醒讀者去經驗自己的生命禮物。 / The study is exploring the experience of the researcher participates the Osho Mystic Rose activity and what is the meaning of these life experiences.So the researcher will participate the group activity and narrates what he experiences. From the activity,the researcher feels that the process of the activity is a kind of therapy from head to heart.So the researcher can see clearly his relationship,desire,personality trait,and psycho-body situation.Then in the process of activity,the discomfort of psycho-body slowly disappears and the model of researcher’s relationship changes.The researcher also has an insight about the base of the work of helping others.The researcher also see the deeper emotion state from the record of the face pictures of the process of the activity. From the meta-story,the researcher finds that his childhood experience has influenced the present relationship,work,and the life’s attitude.And by participating the activity,the researcher’s state is changed and.the life energe is rising.Otherwise,the researcher is awaring that the helper’s blooming life is the root of the work of helping others. About the self-reflection of study,it can be discriminated two levels—participant and researcher.In the participant level,I find that I,the brother of psychotic handicap is against the dominant psychology and psychiatry to show the bitterness.But I forget to translate the opposed energy to positive energy to take care myself well.In the researcher level,I.find that it is difficult to use language to transmit experience to others,and maybe the east wisdom can be applied to the wok of helping others. In advice,the researcher suggested something important about leading the transpersonal psychotherapy group. It is that the group leader should construct the secure environment to let members exploring themselves freely and keep in touch with the present. Finally,the last part,Dialog,it shows and compares researcher’s experiences in different spirit-training groups.And from the point of view of being,the researcher’s insight from activity can not be fitted to others.
238

俄羅斯與美國在喬治亞的戰略競逐 / The Strategic Competition between Russia and the United States in Georgia

王嘉瑜 Unknown Date (has links)
上世紀末蘇聯的崩潰讓喬治亞的地緣政治產生了根本性的質變,喬治亞在歐亞大陸的地緣政治地位提升,較蘇聯時期更具有地緣政治價值。過去的喬治亞是蘇聯維護國家利益與國防安全的關鍵國家,它是蘇聯在黑海的門戶,高加索與中亞的進出口貿易都必須過境喬治亞,同時它也是蘇聯與北約之間的重要邊防區。然而,俄羅斯與喬治亞各自獨立之後,兩國的合作關係不復存在,雙方因劃界爭議、族群衝突、軍事基地等問題嫌隙日增,漸行漸遠。另一方面,美國亦來到裏海地區爭奪能源利益,喬治亞的通道位置與戰略價值吸引了美國的關注,喬治亞於是成為美、俄兩強進行地緣戰略競逐的舞台。 本文以地緣政治學與國際關係的現實主義論做為研究途徑,觀察俄、美兩國在喬治亞的戰略競逐。筆者首先藉由回顧地緣政治學理論與國際關係現實主義論,探討喬治亞的地緣政治價值、地緣政治要素以及喬治亞對於俄、美兩國的戰略意義。在正文的部分,筆者分別討論了俄羅斯與美國在喬治亞的地緣政治活動,以地緣利益、地緣政治威脅、地緣政治實踐等三個面向深入分析俄喬、美喬的雙邊關係。如俄、美與喬治亞的合作關係;俄、美在裏海能源利益的爭奪;俄、美對於喬治亞加入北約的立場;俄、美對玫瑰革命的立場以及俄、美與2008俄喬衝突的關係。 最後,本文的研究發現將俄、美在喬治亞的戰略競逐分為三個時期,第一個時期是俄羅斯掌握傳統影響力,美國進入裏海能源領域(1991~1996年);第二個時期是美國積極經營,俄羅斯處於被動(1997~2003年);第三個時期是美國掌控主動權,俄羅斯伺機反擊(2004~2009年)。在這三個時期,俄羅斯與美國在喬治亞的地緣政治影響力呈現此消彼長的態勢,俄羅斯無力阻止美國在喬治亞軍事、經濟、政治上的積極布局,俄羅斯步步退讓,逐漸喪失在喬治亞的地緣政治影響力。然而,2008年的俄喬衝突卻有了戲劇化的發展,俄、美在喬治亞的勢力重新洗牌,美國依舊擁有提比里斯政權的支持,與喬治亞進一步合作,繼續維護美國在喬治亞的地緣利益。俄羅斯雖然與提比里斯的關係低到冰點以下,但卻得到分離地區阿布哈茲與南奧塞梯亞的支持,俄羅斯透過與阿布哈茲和南奧塞梯亞的合作關係控制兩地,從而維繫在喬治亞的地緣利益與外高加索的地緣政治空間。未來,喬治亞預料仍將因其地緣政治的重要性,持續做為俄羅斯與美國地緣戰略競逐的重要舞台。 / The collapse of Soviet Union in the last century fundamentally changed the geopolitics of Georgia. Its geopolitical values in the Eurasian continent have been improved after the Soviet Union era. In the past, Georgia was a key country that Soviet Union utilized to maintain its country interest and defense security. It served as an entrance to the Black Sea for Soviet Union, as the import and export trading between Caucasus and Middle East relied on it. Meanwhile, it was also the critical sector between the Soviet Union and NATO. However, Russia and Georgia have stopped cooperation since their respective independence; both parties had ceased partnership due to issues of border demarcation, ethnic conflicts, military bases, etc. On the other hand, the United States also competed for its energy interest in the Caspian Sea region, and the passage and strategic values of Georgia has drawn attention of the United States. Georgia, therefore, has become a stage of geostrategic competition for the two superpowers that are the United States and Russia. This study utilizes the geopolitics and realism theory of the international relations as an approach to observe the strategic competition of the United States and Russia in the Georgia. First, I reviewed the geopolitics and realism theory of the international relations and discuss the geopolitical values and elements of Georgia, as well as its strategic meanings for the United States and Russia. In the thesis, the geopolitical activities of the United States and Russia are discussed respectively. The bilateral relations between Russia and Georgia, as well as the United States and Georgia are deeply analyzed in terms of geo-economic benefits, geopolitical threats and geopolitical practices, including the cooperative relations for Georgia with Russia and the United States; the competition for energy interest in the Caspian Sea region between the United States and Russia; the positions of the United States and Russia on joining NATO for Georgia; the positions of the United States and Russia on the Rose Revolution; and the conflict relations between Russia and the United States on the 2008 Russia-Georgia Conflict (South Ossetia War). Finally, the findings of this study divide the strategic competition of the United States and Russia in Georgia into three periods: The first period is that Russia had traditional power and the United States meddled in the Caspian Sea region for energy (1991~1996); the second period is that the United States operated actively while Russia operated passively (1997~2003); and the third period is during which the United States took the initiative while Russia waited for the opportune moment to counterattack (2004~2009). The geopolitical influences of the United States and Russia on Georgia have been constantly changed through these three periods. Russia was unable to strategically stop the military, political, economic plans of the United States in Georgia and had gradually lost its geopolitical influence on it. However, the conflicts between Russia and Georgia in 2008 had a dramatic development. The influences on Georgia of the United States and Russia have been changed again. While the United States have gained Tbilisi’s support to continue cooperation with Georgia to maintain the geo-economic benefits in Georgia, and while Russia has a bad relationship with Tbilisi, Russia has gained support from the two breakaway regions, Abkhazia and South Ossetia. Russia controls these two regions by cooperating with them to maintain the geopolitical interest in Georgia and the geopolitical space in South Caucasus. Due to its geopolitical significance, it is expected that Georgia will continue to serve as a critical stage of the geostrategic competition between the United States and Russia.
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Modélisation multi-échelle et simulation numérique de l'érosion des sols de la parcelle au bassin versant

Minh-Hoang, Le 26 November 2012 (has links) (PDF)
L'objectif global de ce travail est d'étudier une modélisation multi-échelle et de développer une méthode adaptée pour la simulation numérique du processus d'érosion à l'échelle du bassin versant. Après avoir passé en revue les différents modèles existants, nous dérivons une solution analytique non triviale pour le système couplé modélisant le transport de sédiments par charriage. Ensuite, nous étudions l'hyperbolicité de ce système avec diverses lois de sédimentation proposées dans la littérature. Concernant le schéma numérique, nous présentons le domaine de validité de la méthode de splitting, pour les équations modélisant l'écoulement et celle décrivant l'évolution du fond. Pour la modélisation du transport en suspension à l'échelle de la parcelle, nous présentons un système d'équations couplant les mécanismes d'infiltration, de ruissellement et le transport de plusieurs classes de sédiments. L'implémentation et des tests de validation d'un schéma d'ordre élevé et de volumes finis bien équilibré sont également présentés. Ensuite, nous discutons sur l'application et la calibration du modèle avec des données expérimentales sur dix parcelles 1m2 au Niger. Dans le but d'aboutir la simulation à l'échelle du bassin versant, nous développons une modélisation multi échelle dans laquelle nous intégrons le taux d'inondation dans les équations d'évolution afin de prendre en compte l'effet à petite échelle de la microtopographie. Au niveau numérique, nous étudions deux schémas bien équilibrés : le schéma de Roe basé sur un chemin conservatif, et le schéma avec reconstruction hydrostatique généralisée. Enfin, nous présentons une première application du modèle avec les données expérimentales du bassin versant de Ganspoel qui nécessite la parallélisation du code.
240

Artificial Magnetic Materials: Limitations, Synthesis and Possibilities

Kabiri, Ali January 2010 (has links)
Artificial magnetic materials (AMMs) are a type of metamaterials which are engineered to exhibit desirable magnetic properties not found in nature. AMMs are realized by embedding electrically small metallic resonators aligned in parallel planes in a host dielectric medium. In the presence of a magnetic field, an electric current is induced on the inclusions leading to the emergence of an enhanced magnetic response inside the medium at the resonance frequency of the inclusions. AMMs with negative permeability are used to develop single negative, or double negative metamaterials. AMMs with enhanced positive permeability are used to provide magneto-dielectric materials at microwave or optical frequencies where the natural magnetic materials fail to work efficiently. Artificial magnetic materials have proliferating applications in microwave and optical frequency region. Such applications include inversely refracting the light beam, invisibility cloaking, ultra miniaturizing and frequency bandwidth enhancing low profile antennas, planar superlensing, super-sensitive sensing, decoupling proximal high profile antennas, and enhancing solar cells efficiency, among others. AMMs have unique enabling features that allow for these important applications. Fundamental limitations on the performance of artificial magnetic materials have been derived. The first limitation which depends on the generic model of permeability functions expresses that the frequency dispersion in an AMM is limited by the desired operational bandwidth. The other constraints are derived based on the geometrical limitations of inclusions. These limitations are calculated based on a circuit model. Therefore, a formulation for permeability and magnetic susceptibility of the media based on a circuit model is developed. The formulation is in terms of a geometrical parameter that represents the geometrical characteristics of the inclusions such as area, perimeter and curvature, and a physical parameter that represents the physical, structural and fabrication characteristics of the medium. The effect of the newly introduced parameters on the effective permeability of the medium and the magnetic loss tangent are studied. In addition, the constraints and relations are used to methodically design artificial magnetic material meeting specific operational requirements. A novel design methodology based on an introduced analytical formulation for artificial magnetic material with desired properties is implemented. The synthesis methodology is performed in an iterative four-step algorithm. In the first step, the feasibility of the design is tested to meet the fundamental constraints. In consecutive steps, the geometrical and physical factors which are attributed to the area and perimeter of the inclusion are synthesized and calculated. An updated range of the inclusion's area and perimeter is obtained through consecutive iterations. Finally, the outcome of the iterative procedure is checked for geometrical realizability. The strategy behind the design methodology is generic and can be applied to any adopted circuit based model for AMMs. Several generic geometries are introduced to realize any combination of geometrically realizable area and perimeter (s,l) pairs. A realizable geometry is referred to a contour that satisfies Dido's inequality. The generic geometries introduced here can be used to fabricate feasible AMMs. The novel generic geometries not only can be used to enhance magnetic properties, but also they can be configured to provide specific permeability with desired dispersion function over a certain frequency bandwidth with a maximum magnetic loss tangent. The proposed generic geometries are parametric contours with uncorrelated perimeter and area function. Geometries are configured by tuning parameters in order to possess specified perimeter and surface area. The produced contour is considered as the inclusion's shape. The inclusions are accordingly termed Rose curve resonators (RCRs), Corrugated rectangular resonators (CRRs) and Sine oval resonators (SORs). Moreover, the detailed characteristics of the RCR are studied. The RCRs are used as complementary resonators in design of the ground plane in a microstrip stop-band filter, and as the substrate in design of a miniaturized patch antenna. The performance of new designs is compared with the counterpart devices, and the advantages are discussed.

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