Thermal transport across three-dimensional Lennard-Jones superlattices, two-dimensional heterostructures of graphene and hexagonal boron nitride (hBN), and in C60 molecular crystals is studied atomistically. The first two systems are studied as finite junctions placed between bulk leads, while the molecular crystal is studied as a bulk. Two computational methods are used: molecular dynamics (MD) simulations and harmonic lattice dynamics calculations in conjunction with the scattering boundary method (SBM). In Lennard-Jones superlattice junctions with a superlattice period of four atomic monolayers at low temperatures, those with mass-mismatched leads have a greater thermal conductance than those with mass-matched leads. We attribute this lead effect to interference between and the ballistic transport of emergent junction vibrational modes. The lead effect diminishes when the temperature is increased, when the superlattice period is increased, and when interfacial disorder is introduced, and is reversed in the harmonic limit. In graphene-hBN heterostructure junctions, the thermal conductance is dominated by acoustic phonon modes near the Brillouin zone center that have high group velocity, population, and transmission coefficient. Out-of-plane modes make their most significant contributions at low frequencies, whereas in-plane modes contribute across the frequency spectrum. Finite-length superlattice junctions between graphene and hBN leads have a lower thermal conductance than comparable junctions between two graphene leads due to lack of transmission in the hBN phonon band gap. The thermal conductances of bilayer systems differ by less that 10% from their single-layer counterparts on a per area basis, in contrast to the strong thermal conductivity reduction when moving to from single- to multi-layer graphene. We model C60 molecules using the polymer consistent force-field and compute the single molecule vibrational spectrum and heat capacity. In the face-center cubic C60 molecular crystal at a temperature of 300 K, we find three frequency peaks in the center-of-mass translations at 20, 30 and 38 cm􀀀1, agreeing with the average frequencies of the three acoustic branches of the frozen phonon model of the same system and suggesting that a phonon description of center-of-mass translations. We use both direct method and Green- Kubo MD simulations to predict the thermal conductivity of the molecular crystals at a temperature of 300 K. We find that the thermal conductivity of the molecular crystal is 20 to 50% lower than that of a reduced order model where only molecular center-ofmass translations are present, suggesting that molecular vibrations and rotations act as significant scattering sources for the center-of-mass phonons.

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La dynamique du geste reste peu exploitée dans le domaine de l’interaction hommemachinealors qu’elle permet de définir des critères simples d’analyse de l’intention desutilisateurs. Sa principale utilisation porte sur les fonctions de transfert des périphériquesisotoniques. Ces fonctions permettent d’établir une relation entre le geste de l’utilisateureffectué dans l’espace moteur avec le périphérique de pointage (i.e. souris) et le mouvementdu pointeur dans l’espace visuel. Les fonctions de transfert utilisées par les systèmesd’exploitation modernes restent cependant fortement méconnues même si des études ontmontré qu’elles ont un impact sur les performances des utilisateurs. Pour caractériser cesfonctions, nous avons développé un périphérique électronique qui simule une souris réelleet qui permet d’obtenir les fonctions de transfert de tout système. Nous avons ainsi puobtenir les fonctions des systèmes Windows, Linux et Mac et nous avons observé des différencesnotables entre ces fonctions. Nous avons ensuite cherché à optimiser ces fonctionsen réduisant au maximum le nombre de leurs degrés de liberté. En faisant varier de manièreexhaustive ces paramètres, nous avons ainsi pu observé des différences significativesqui montrent qu’il existe une famille de fonctions pour lesquelles les performances sontoptimales. Enfin, nous nous sommes intéressés à l’utilisation de la dynamique du gestedans un autre contexte, celui de la génération d’événements discrets, pertinent dans lecadre des interfaces sans contact de type Kinect. Nous avons ainsi montré qu’il est possiblede distinguer la sélection du déplacement dans une tâche d’interaction 3D. La techniquedéveloppée est ensuite améliorée dans le cas des cibles de petites tailles et son applicationdans un contexte d’interaction 2D est évaluée. / The dynamic of the gesture is not used a lot in the domain of human-computer interaction,while it can help to define some simple heuristics to analyze the intents of users.Its first use is related to transfer functions for isotonic devices. Those functions establisha relationship between the gesture of the user, executed in motor space with the pointingdevice (i.e. a mouse), and the movement of the pointer in the visual space. The transferfunctions used by modern operating systems are still not well known, even if somestudies have shown they have an impact on user’s performance. To characterize thosefunctions, we have developed an electronic device which simulates a real mouse, and thatcan retrieve the transfer functions of any system. We have then exposed the functions ofthe Windows, Linux and Mac systems, and we observed some visible differences betweenthose functions. We have then tried to optimize those functions by reducing their numberof degrees of freedom. By varying those parameters in an exhaustive way, we have thenobserved some significant differences that show there is a family of functions for whichperformances are optimal. Finally, we were interested in the use of the dynamic of thegesture in another context : the generation of discrete events, useful when dealing withcontact-less interfaces, like the Kinect. We have shown that it is possible to distinguishbetween picking and drag’n’drop in a 3D interaction task. The technique is then improvedin the case of small size targets, and its application in a 2D interaction context isevaluated.

[pt] Este estudo focaliza a aquisição do aspecto verbal no português, no contexto de uma teoria da aquisição da linguagem que visa a caracterizar o modo como a criança percebe informação gramaticalmente relevante, visível nas interfaces fônica e semântica da língua com os sistemas perceptual/articulatório e conceputual/intencional, respectivamente, a partir do início do segundo ano de vida. A dissertação baseia-se nos pressupostos do Programa Minimalista (Chomsky, 1995; 1999) e numa proposta teórica que visa a uma articulação entre teoria lingüística e psicolingüística no estudo da aquisição da linguagem (Corrêa, 2005a; 2006). A hipótese de trabalho é a de que a criança reconhece aspecto como um traço formal da língua inicialmente a partir de variações morfofonológicas na classe fechada dos afixos verbais, em termos de formas marcadas e não marcadas, ainda de maneira indissociada da informação pertinente a tempo, e que distinções relativas a perfectividade são posteriormente estabelecidas com base no processamento na interface semântica. Investiga-se em que medida informação referente a traços semânticos da raiz verbal concernentes a aspecto lexical (como telicidade, por exemplo) interage com a informação relativa a perfectividade proveniente de variações na forma dos afixos verbais. Com este fim, uma metodologia experimental é desenvolvida, com vistas a dissociar a percepção de informação proveniente das interfaces fônica e semântica relativa a tempo/aspecto. Explora-se o paradigma da detecção de novidade, tradicionalmente utilizado no estudo do desenvolvimento conceptual não-lingüístico, na percepção de informação fônica (formas marcadas de tempo/aspecto como novidade) e conceptual (evento concluído como novidade). Um experimento-piloto, conduzido com crianças de 18-28 meses, é relatado. Um segundo experimento, com crianças de 3 e 5 anos, conduzido com a técnica da manipulação de brinquedos, é reportado, no qual telicidade e perfectividade são variáveis manipuladas. Os resultados são discutidos com relação à metodologia para o estudo do processamento na interface semântica, e em relação a dados da produção de distinções aspectuais na fala espontânea de crianças e hipóteses correntes na literatura em aquisição da linguagem quanto ao papel de informação semântica no estabelecimento de distinções gramaticais. / [en] This study focuses on the acquisition of verbal aspect in Portuguese, in the context of theory of language acquisition that aims at characterizing the way children perceive grammatically relevant information at the interface levels between language and articulatory/phonetic and conceptual/intentional systems - phonetic and semantic interfaces, respectively. It is based on the assumptions of the Minimalist Program (Chomsky, 1995; 1999) and on a theoretical approach to language acquisition requiring articulation between a linguistic model of language and psycholinguistic models of language processing (Corrêa, 2005a; 2006). The working hypothesis is that the child initially recognizes aspect as a formal feature on the basis of morphophonological variations in the closed class of verbal affixes (marked vs. unmarked forms), when tense and aspect are undissociated. Distinctions concerning perfectivity would be established later on, on the basis of processing at the semantic interface. The extent to which information pertaining to semantic features of the verbal root (such as telicity) interacts with information concerning perfectivity provided by variation in the form of verbal affixes is considered. An experimental methodology is developed, which is intended to enable the perception of information concerning tense/aspect from the phonetic and the semantic interfaces to be dissociated. The novelty detection paradigm, traditionally used in the study of conceptual development, was explored here so that novelty could be detected both in the perception of the form of affixes and in the perception of a visually presented event. A pilot- experiment conducted with 18- 28 month old children is reported. An acting-out experiment, conducted with 3-5 year olds, is also presented, in which telecity and perfectivity were the independent variables. Questions concerning methodology for the study of processing at the semantic interface are considered, and the results are discussed in relation to children´s spontaneous production data regarding aspectual contrasts and current hypotheses on the role of semantic information in the establishment of grammatical distinctions.

液滴撞在固體上是個常見現象並且有廣泛的應用，譬如噴墨打印，塗層，工業冷卻以及飛機上的積冰。當液滴撞在乾燥的表面上會出现很多的結果：它可能完全反彈，或平緩的展開，或猛烈地飛濺出許多微小的液滴。影響撞擊過程包括撞擊速度，液體和固體的性質以及周圍的空氣。最近的研究發現降低周圍氣體壓強可以抑制液體飛濺。這表明空氣對於飛濺機制起了關鍵作用。因此，了解在液固撞擊過程中空氣的重要性會給這一基本現象帶來新的發展，並可能改善如控制飛濺和表面塗層等一些實踐過程。 / 採用高速攝影和顯微成像技術，我們做了液滴撞擊光滑且乾燥固體表面的實驗，研究了被困在裡面的氣體。我們觀察了在液體接觸襯底之前一層氣膜被壓縮並形成的過程，發現其壓強比大氣壓值要高得多。壓縮程度取決於撞擊速度，我們通過減速的液體與壓縮空氣的平衡關係給出了解釋。在液體與襯底接觸後，空氣膜的邊緣在豎直方向上擴展，壓強在幾十微秒內迅速降低。這個厚的邊沿在表面張力，慣性力和粘性阻力的複雜相互作用下最終收縮成氣泡。 / 當液滴以很高的速度撞擊平滑固體表面上，液體發生飛濺。人們對這個常見的現象缺乏基本的了解。採用高速攝影技術，我們觀察到是被困在展開液體前沿下的超薄氣膜觸發了飛濺現象。因為這層薄膜比空氣分子的平均自由程更薄，具有與聲速相當的非常高速來轉移動量，並產生一個比常規計算強十倍的應力。如此"強風"在小尺度上開起了開爾文-亥姆霍茲不穩定性並且有效地產生飛濺。我們的模型定量地與實驗驗證相符，並給出了一個對於液滴在光滑表面上飛濺的基本解釋。 / The impacts of liquid drops onto solid substrates are ubiquitous and appear in a variety of applications, such as ink-jet printing, spray coating, industrial cooling processes and ice accumulation on aircraft. When a liquid drop hits a dry substrate, there are many possible outcomes: it can rebound completely, spread smoothly, or splash dramatically ejecting many tiny daughter droplets. Clearly, the hitting dynamics may be influenced by different factors, including the velocity of impact, liquid and surface properties, as well as the surrounding air. Recent study reveals that by lowering the ambient gas pressure, liquid splash could be eliminated. It indicates that the role of air is a significant key to the mechanism of splash creation. Therefore, understanding the behavior of air during liquid-solid impacts will bring new advances to this fundamental phenomenon, and may benefit practical processes such as splash control and surface coating. / Using high-speed photography coupled with optical interference, we experimentally study the air entrapment during a liquid drop impacting a smooth and dry solid substrate. We observe the formation of a compressed air film before the liquid touches the substrate, with internal pressure considerably higher than the atmospheric value. The degree of compression highly depends on the impact velocity, as explained by balancing the liquid deceleration with the large pressure of the compressed air. After contact, the air film expands vertically at the edge, reducing its pressure within a few tens of microseconds and producing a thick rim on the perimeter. This thick-rimmed air film subsequently contracts into an air bubble, governed by the complex interaction between surface tension, inertia and viscous drag. Such a process is universally observed for impacts above a few centimeters high. / When a fast-moving drop impacts onto a smooth substrate, splashing will be produced at the edge of the expanding liquid sheet. This ubiquitous phenomenon lacks a fundamental understanding. With high speed photography, we illustrate that an ultra-thin air film trapped at the expanding liquid front triggers splashing. Because this film is thinner than the mean free path of air molecules, the interior air flow transfers momentum with an unusually high velocity comparable to the speed of sound, and generates a stress ten times stronger than the conventional calculation. Such a "strong wind" initiates Kelvin-Helmholtz instabilities at small length scales and effectively produces splashing. Our model agrees quantitatively with experimental verifications, and brings a fundamental understanding to the ubiquitous phenomenon of drop splashing on smooth substrates. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Liu, Yuan = 液體固體碰撞過程中空氣重要性的研究 / 劉嫄. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 78-80). / Abstracts also in Chinese. / Liu, Yuan = Ye ti gu ti peng zhuang guo cheng zhong kong qi zhong yao xing de yan jiu / Liu Yuan.

La presente tesis tiene como objetivo el desarrollo de una interfaz hombremáquina basada en una tarjeta de adquisición en una computadora. Esta interfaz, permitió visualizar y analizar la información proveniente de los sistemas de detección de fallos en los lazos de control de la planta estudiada. Asimismo, también permitió visualizar la evolución de las variables y actuar sobre estas cuando fue necesario. El trabajo propuesto incluyó, el estudio de metodologías de desarrollo de interfaces, el desarrollo de software de la interface visual, el desarrollo de las librerías de registro de información proveniente de los sistemas de detección de fallos y desarrollo del algoritmos de monitoreo y control de las variables de la planta objeto de estudio. / Tesis

Hoy en día los científicos necesitan de aplicaciones de cómputo para realizar cálculos, validar modelos matemáticos o hacer simulaciones; requiriendo para esto del procesamiento de un gran volumen de datos. En ocasiones, los requerimientos computacionales para realizar estas tareas exceden las prestaciones que les puede brindar una computadora personal. En vista de esto, es necesario contar con una infraestructura de mayor escala, la cual permita realizar cálculos intensivos. / Tesis

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Solid particles tend to adhere to fluid interfaces under the action of capillary force. This adsorption process is robust and has been exploited in lots of applications from stabilisation of emulsions to micro fluidic fabrications. The resulting particle laden fluid interfaces can manifest solid-like behaviours. The modifi cation of the surface tension and the emergence of surface shear elasticity of a particle-covered drops are attributed to the particle-induced surface stress. This stress represents at the continuum level the microscopic effect of particle-particle interactions. Understanding the link between the surface stress and the particle arrangement are crucial for creating novel soft materials in the future. A challenge remains when carrying out numerical simulations of particle-laden fluid interfaces: the large separation of scales makes the direct numerical simulations extraordinary expensive. Physical features present in the system come from both the liquid meniscus on the surface of each particle and the fluid interfaces containing thousands of particles. Motivated by the need for a fast simulation method to study problems involving particle-laden fluid interface, this thesis presents a new numerical formulation named Fast Interface Particle Interaction (FIPI) that can be used to simulate a large number of solid particles absorbed on fluid interfaces at a moderate computational cost. The outstanding performance of this new method is attributed to the fact that particle-level phenomena are modelled with analytical or semi-empirical expressions while hydrodynamics and fluid interface morphology at larger scales are fully resolved. Two important studies of particle-covered drops have been carried out with FIPI. In the first one a particle-covered pendant drop is simulated. The result reveals that the FIPI can successfully capture the modulation of surface tension made by absorbed particles. Moreover, the information of anisotropic surface stress is now directly available on the fluid interfaces. This capability has not been achieved previously in both experiments and simulations. The anisotropic stress emerged on the surface of a pendant drop is caused by anisotropic arrangement of the particles on the interface which in turn is induced by stretching of the interface due to gravity. Once the surface tension of the fluid interface is reduced below zero, the Laplace pressure inside the drop becomes negative and the drop can buckle like a thin solid elastic shell under compression. In the second study, the behaviours of a particle covered spherical drop under compression have been explored. The simulation results indicate the possibilities of particle desorption as well as fluid interface buckling. The onset of desorption is highly correlated to small-scale monolayer undulations which can greatly amplify the normal forces pushing particles out of the interface. The behaviours of a particle-covered drop under compression depend on the combination of several parameters related to the properties of the particle and the surface pressure created by the monolayer.

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