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QP Partitioning for Radiationless TransitionsLavigne, Cyrille 18 March 2014 (has links)
This work presents a new implementation of the QP algorithm, a computer method to diagonalize the extremely large matrices arising in multimode vibronic problems. Benchmark calculations are included, showing the accuracy of the program. The QP algorithm is extended to treat multiple electronic surfaces for competitive control and this is demonstrated with an Hamiltonian including three electronic states, a model of the benzene radical cation. Finally, the evolution of zeroth-order states in a simple two electronic states, two dimensional model with a conical intersection is explored, towards building a time-dependent view of overlapping resonances coherent control.
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QP Partitioning for Radiationless TransitionsLavigne, Cyrille 18 March 2014 (has links)
This work presents a new implementation of the QP algorithm, a computer method to diagonalize the extremely large matrices arising in multimode vibronic problems. Benchmark calculations are included, showing the accuracy of the program. The QP algorithm is extended to treat multiple electronic surfaces for competitive control and this is demonstrated with an Hamiltonian including three electronic states, a model of the benzene radical cation. Finally, the evolution of zeroth-order states in a simple two electronic states, two dimensional model with a conical intersection is explored, towards building a time-dependent view of overlapping resonances coherent control.
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A Monte Carlo Study Investigating the Influence of Item Discrimination, Category Intersection Parameters, and Differential Item Functioning in Polytomous ItemsThurman, Carol Jenetha 21 October 2009 (has links)
The increased use of polytomous item formats has led assessment developers to pay greater attention to the detection of differential item functioning (DIF) in these items. DIF occurs when an item performs differently for two contrasting groups of respondents (e.g., males versus females) after controlling for differences in the abilities of the groups. Determining whether the difference in performance on an item between two demographic groups is due to between group differences in ability or some form of unfairness in the item is a more complex task for a polytomous item, because of its many score categories, than for a dichotomous item. Effective DIF detection methods must be able to locate DIF within each of these various score categories. The Mantel, Generalized Mantel Haenszel (GMH), and Logistic Regression (LR) are three of several DIF detection methods that are able to test for DIF in polytomous items. There have been relatively few studies on the effectiveness of polytomous procedures to detect DIF; and of those studies, only a very small percentage have examined the efficiency of the Mantel, GMH, and LR procedures when item discrimination magnitudes and category intersection parameters vary and when there are different patterns of DIF (e.g., balanced versus constant) within score categories. This Monte Carlo simulation study compared the Type I error and power of the Mantel, GMH, and OLR (LR method for ordinal data) procedures when variation occurred in 1) the item discrimination parameters, 2) category intersection parameters, 3) DIF patterns within score categories, and 4) the average latent traits between the reference and focal groups. Results of this investigation showed that high item discrimination levels were directly related to increased DIF detection rates. The location of the difficulty parameters was also found to have a direct effect on DIF detection rates. Additionally, depending on item difficulty, DIF magnitudes and patterns within score categories were found to impact DIF detection rates and finally, DIF detection power increased as DIF magnitudes became larger. The GMH outperformed the Mantel and OLR and is recommended for use with polytomous data when the item discrimination varies across items.
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Evaluation of the LHOVRA O-function using the microsimulation tool VISSIMHarirforoush, Homayoun January 2012 (has links)
The growth of serious injuries and fatalities resulting from traffic accidents at intersections is one of the main problems in urban areas. Signal control was proposed as an alternative intersection design on rural roads. There were many reasons behind this, the most outstanding of which was the traffic signals can be used as a cost effective tools for traffic management in urban areas. The LHOVRA technique was intended to improve safety and reduce lost time at signalized intersection along high speed roads. The LHOVRA technique is an isolated traffic control strategy in Sweden which is formed from different concepts. This thesis work is aimed to evaluate the LHOVRA technique with a focus on the O-function. Hence, two different scenarios, one with O-function and one without O-function were implemented in the micro traffic simulation software, VISSIM. VISSIM has been used to simulate the traffic situation of the Gamla Övägen – Albrektsvägen intersection by considering the LHOVRA scenario (with O-function) as well as traditional scenario (without O-function) of the intersection. Field measurements were used as input data for VISSIM simulation. The VISSIM simulation model was calibrated to find a close match between simulated and real data. Finally, a comparison of alternatives was carried out based on traffic performance and traffic safety measurements. The simulation experiment results gained by the comparisons were presented a higher time-to-collision value. The higher time-to-collision value the safer situation is. Both delays and travel time were reduced to primary road traffic.
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Du atsitiktinių grafų modeliai / On two models of random graphsKurauskas, Valentas 16 December 2013 (has links)
Šioje santraukoje trumpai aprašoma V. Kurausko disertacija. Pristatomos abi disertacijos dalys, įvedami atsitiktinių sankirtų grafų ir digrafų modeliai, apibrėžiamos minorinės grafų klasės, suformuluojami sprendžiami uždaviniai bei pateikiami pagrindiniai rezultatai. / This paper summarizes (in Lithuanian) the doctoral dissertation "On two models of random graphs" (in English) by V. Kurauskas. We introduce the random graph models (random intersection graphs, graphs with disjoint excluded minors) studied in the thesis, overview the problems and state the main results.
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New combinatorial techniques for nonlinear ordersMarcus, Adam Wade 26 June 2008 (has links)
This thesis focuses on the use of extremal techniques in analyzing problems that historically have been associated with other areas of discrete mathematics. We establish new techniques for analyzing combinatorial problems with two different types of nonlinear orders, and then use them to solve important previously-open problems in mathematics. In addition, we use entropy techniques to establish a variety of bounds in the theory of sumsets.
In the second chapter, we examine a problem of Furedi and Hajnal regarding forbidden patterns in (0,1)-matrices. We introduce a new technique that gives an asymptotically tight bound on the number of 1-entries that a (0,1)-matrix can contain while avoiding a fixed permutation matrix. We use this result to solve the Stanley-Wilf conjecture, a well-studied open problem in enumerative combinatorics. We then generalize the technique to give results on d-dimensional matrices.
In the third chapter, we examine a problem of Pinchasi and Radoicic on cyclically order sets. To do so, we prove an upper bound on the sizes of such sets, given that their orders have the intersection reverse property. We then use this to give an upper bound on the number of edges that a graph can have, assuming that the graph can be drawn so that no cycle of length four has intersecting edges. This improves the previously best known bound and (up to a log-factor) matches the best known lower bound. This result implies improved bounds on a number of well-studied problems in geometric combinatorics, most notably the complexity of pseudo-circle arrangements.
In the final chapter, we use entropy techniques to establish new bounds in the theory of sumsets. We show that such sets behave fractionally submultiplicatively, which in turn provides new Plunecke-type inequalities of the form first introduced by Gyarmati, Matolcsi, and Ruzsa.
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Le contrôle continu de l'interception d'un créneau temporel en mouvement : Le cas de la traversée d'intersection. / Continuous control of the interception of a moving gap : The case of road crossing at intersectionLouveton, Nicolas 05 October 2012 (has links)
L'objectif de cette thèse est d'étudier le comportement de traversée d'intersection en conduite automobile sous l'angle des actions visuellement guidées. Dans l'introduction, nous montrons que les principales études portant sur la traversée d'intersection se sont focalisées sur les processus de jugement perceptif ; or nous montrons que la compréhension de cette activité pourrait être affinée en utilisant les concepts de la théorie de la perception directe et ceux issus du contrôle continu. Notre revue de questions nous conduit à rapprocher la tâche de traversée d'intersection à l'intérieur d'un créneau libre du trafic à celle d'interception de cible se déplaçant horizontalement. Or, dans le cadre des tâches d'interception, il a été démontré que la stratégie d'angle de relèvement constant (i.e., Constant Bearing Angle, CBA) a un fort pouvoir explicatif vis-à-vis des données expérimentales. Nous avons donc tiré partie des outils de simulation automobile pour tester la plausibilité de l'utilisation d'une telle stratégie par les conducteurs. Dans le premier chapitre expérimental, nous montrons qu'il est légitime d'étudier le couplage perception-action dans ce type de tâche et que les conducteurs adoptent des régulations comportementales proches de celles observées dans une tâche d'interception de mobile. Le second chapitre expérimental nous permet de mettre en évidence l'utilisation conjointe par les conducteurs d'informations relatives au créneau du trafic (supports globaux) et aux véhicules (supports locaux). / This Ph.D. project aims at studying drivers' road crossing behaviour under the perspective of visually guided actions. In the introduction, we present that former studies related to road crossing behaviour mainly focused on perceptual judgement processes. However, we demonstrate that this kind of task would be better understood with theories from the ecological approach of perception and motor control studies. Our literature review lead us to make a bridge between the task of crossing a road inside a free moving traffic gap and the task of intercepting an horizontally moving target. In this regard, it has been demonstrated that the Constant Bearing Angle strategy (CBA) has a high explanatory power in respect to experimental data. We used driving simulation tools in order to assess the hypothesis of the use of bearing angle based strategy by drivers. In the first experimental chapter, we show that studying perceptual-motor coupling in this task is relevant and that observed behaviour is close to taht observed in horizontally moving target interception tasks. The second experimental chapter demonstrates that drivers' behaviour relies both on visual information related to the moving gap (global contribution) and that related to the independent vehicles (local contributions). In the last experimental chapter, we evidenced that drivers' behaviour does not exclusively rely on the changes of the bearing angle but also on traffic vehicles' optical expansion. We conclude on how our results shed new light on former results obtained with perceptual-judgements based methodology.
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Rôle de multiples affordances dans la prise de décision et la régulation de l'action chez le conducteur : L'exemple du franchissement d'intersection / Role of multiple affordances in the selection and the control of the driver’s action while attempting to cross an intersectionMarti, Geoffrey 28 May 2015 (has links)
La traversée d’intersection constitue une tâche typique dans laquelle plusieurs affordances coexistent, l’une traduisant les possibilités de franchir l’intersection, l’autre traduisant les possibilités d’immobiliser le véhicule afin d’éviter une collision. En nous inspirant des travaux de Gibson et Crooks (1938), nous avons formalisé les affordances Field of Safe Travel (FST) et Minimum Stopping Zone (MSZ) en termes de temps critique pour réussir le franchissement d’intersection et l’immobilisation du véhicule, respectivement. Grâce à un dispositif de réalité virtuelle et un simulateur de conduite, nous avons testé la prise en compte de ces affordances par un agent engagé dans la tâche de référence à travers trois expérimentations. Les résultats, appuyés par notre modèle de prise de décision, montrent que le conducteur intègre non seulement l’affordance FST, mais aussi l’affordance MSZ, dans sa décision de franchir l’intersection. De plus, l’utilisation conjointe de ces deux affordances rend compte des régulations de vitesses produites par un agent devant réaliser la tâche de franchissement en présence d’un véhicule préprogrammée ou soumis au contrôle d’un autre agent. Ces différents résultats montrent que les agents prennent en compte les différentes possibilités qui leur sont offertes (affordances FST et MSZ) pour faire un choix adapté et réguler leur vitesse. / Crossing an intersection is a typical task in which several affordances coexist, one offering the possibilities to safely cross the intersection (the main goal) and another offering the possibilities to stop the driving car to avoid a collision (the alternative goal). Based on Gibson and Crooks’ works (1938), we formalized the so-called Field of Safe Travel (FST) and Minimum Stopping Zone (MSZ) affordances in terms of critical time for safe crossing and for safe stopping, respectively. Using a virtual reality set-up with a driving simulator, three experiments have been designed to test the role of these two affordances on the decision-making and the regulation of action process. Our results, supported by a model of decision-making, reveal that drivers rely not only on the FST affordance, but also on the MSZ affordance, to choose to cross-or-not the intersection. Moreover, the joint use of these affordances is still observed when drivers have to control their velocity to perform the task when either a vehicle with a computed kinematic or a car driven by another agent is approaching. Put together, these results show that drivers take into account several possibilities for action offered by the environment (FST and MSZ affordances) to make a suitable choice and to control their speed when approaching an intersection.
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Endemias ficcionais e o discurso da arte como vetores da prática artísticaRocha, Michel Zózimo da January 2008 (has links)
A presente pesquisa consiste na análise do processo de trabalho do Notorium Magnificus 132mg – Droga de Artista - uma embalagem de medicamento, uma bula prescritiva e uma série de materiais publicitários. A idéia de que poderia haver distúrbios sistêmicos e doenças fictícias ocasionadas no sistema da arte atual, configura-se por meio de um entrecruzamento de discursos artísticos e farmacêuticos. Neste sentido, a bula do Notorium Magnificus 132mg – Droga de Artista se apresenta como uma prática de inserção, porém abre uma outra via que não é tão somente a da citação da arte, nem a da inserção da arte nos circuitos industriais, mas que opera difusa entre realidade e ficção, como leitura. / The present research consists on the analysis of the work process of the Notorium Magnificus 132mg – Drug of Artist, composed of a packing-case, printed directions for its use and a series of advertisement material. The idea that it could occur systemic disturbances and fictitious diseases inside the contemporary Art system is configured by an intersection between artistic discourse and pharmaceutical ones. In this sense, the Notorium Magnificus 132mg – Drug of Artist - presents itself as an insertion practice; however, it opens another path that is not only the Art quotation nor the Art insertion in the industrial circuit, but one that operates diffused between the reality and the fiction, as a reading.
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Formal Modeling Can Improve Smart Transportation Algorithm DevelopmentWathugala, Wathugala Gamage Dulan Manujinda 06 1900 (has links)
201 pages / Ensuring algorithms work accurately is crucial, especially when they drive
safety critical systems like self-driving cars.
We formally model a published distributed algorithm for autonomous
vehicles to collaborate and pass thorough an intersection. Models are built and
validated using the “Labelled Transition System Analyser” (LTSA). Our models
reveal situations leading to deadlocks and crashes in the algorithm.
We demonstrate two approaches to gain insight about a large and complex
system without modeling the entire system: Modeling a sub system - If the sub
system has issues, the super system too. Modeling a fast-forwarded state - Reveals
problems that can arise later in a process.
Some productivity tools developed for distributed system development
are also presented. Manulator, our distributed system simulator, enables quick
prototyping and debugging on a single workstation. LTSA-O, extension to LTSA,
listens to messages exchanged in an execution of a distributed system and validates
it against a model.
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