Visual modeling and simulation of multiscale phenomena

Many large-scale systems seen in real life, such as human crowds, fluids, and granular materials, exhibit complicated motion at many different scales, from a characteristic global behavior to important small-scale detail. Such multiscale systems are computationally expensive for traditional simulation techniques to capture over the full range of scales. In this dissertation, I present novel techniques for scalable and efficient simulation of these large, complex phenomena for visual computing applications. These techniques are based on a new approach of representing a complex system by coupling together separate models for its large-scale and fine-scale dynamics. In fluid simulation, it remains a challenge to efficiently simulate fine local detail such as foam, ripples, and turbulence without compromising the accuracy of the large-scale flow. I present two techniques for this problem that combine physically-based numerical simulation for the global flow with efficient local models for detail. For surface features, I propose the use of texture synthesis, guided by the physical characteristics of the macroscopic flow. For turbulence in the fluid motion itself, I present a technique that tracks the transfer of energy from the mean flow to the turbulent fluctuations and synthesizes these fluctuations procedurally, allowing extremely efficient visual simulation of turbulent fluids. Another large class of problems which are not easily handled by traditional approaches is the simulation of very large aggregates of discrete entities, such as dense pedestrian crowds and granular materials. I present a technique for crowd simulation that couples a discrete per-agent model of individual navigation with a novel continuum formulation for the collective motion of pedestrians. This approach allows simulation of dense crowds of a hundred thousand agents at near-real-time rates on desktop computers. I also present a technique for simulating granular materials, which generalizes this model and introduces a novel computational scheme for friction. This method efficiently reproduces a wide range of granular behavior and allows two-way interaction with simulated solid bodies. In all of these cases, the proposed techniques are typically an order of magnitude faster than comparable existing methods. Through these applications to a diverse set of challenging simulation problems, I demonstrate the benefits of the proposed approach, showing that it is a powerful and versatile technique for the simulation of a broad range of large and complex systems

Apprentissage par dictionnaire pour la synthèse des détails de surface d'une simulation de fluide par particules

En infographie, la modélisation de phénomènes naturels, tels que les fluides, est une tâche plutôt complexe et nécessite des temps de calcul importants. De plus, la mise en valeur des détails fins de simulations de fluide, telles que les forces de turbulence en surface, est un sujet actif de recherche dans le domaine des effets visuels. L’intérêt de ces recherches est notamment de conserver ces détails, particulièrement à la surface du fluide. Il peut être parfois difficile d’obtenir le résultat désiré avec de telles simulations. D’ailleurs, le comportement d’une simulation est fortement dépendant du nombre de particules. Certains éléments importants peuvent ressortir simplement en augmentant le nombre de particules d’une simulation. L’énergie cinétique et les forces de turbulence sont aussi des facteurs importants qui peuvent influencer le comportement d’un fluide. L’approche présentée dans ce mémoire a pour but de recréer l’apparence en surface d’une simulation en haute résolution à partir d’une simulation en basse résolution, et ce, à l’aide d’un apprentissage par dictionnaire. L’apprentissage est fait à partir d’un dictionnaire couplé, c’est-à-dire généré à partir de la concaténation de trois dictionnaires. Les dictionnaires permettent d’établir une correspondance entre la géométrie de la surface des exemples appris et certaines propriétés physiques. Les exemples appris sont représentés par des parcelles en surface du fluide. Notre méthode considère ces parcelles comme des champs de hauteurs. Le spectre d’énergie cinétique et les forces de vorticité sont aussi évalués par parcelle afin de conserver certaines propriétés physiques du fluide. La modélisation des nouvelles parcelles est formulée comme un problème d’optimisation sous contraintes géométriques et physiques. Le résultat de la minimisation permet d’obtenir une combinaison linéaire pondérée des atomes du dictionnaire. Ce vecteur creux pondéré est utilisé pour obtenir une représentation à haute résolution de chaque parcelle à basse résolution en entrée. Enfin, un terme de cohérence spatiale doit être ajouté pour forcer les bordures d’une parcelle à être alignées avec celles de ses voisins. Cette approche permet de modéliser l’aspect général de la surface d’un fluide en haute résolution, et ce, uniquement à partir de quelques milliers de particules. De plus, ce traitement est fait en une fraction du temps nécessaire pour générer la simulation en haute résolution. Malgré le fait que les objectifs ne soient pas les mêmes qu’avec des méthodes de synthèse de détail par vortex, notre approche peut être utilisée en complément avec ces dernières

Aeronautical engineering: A continuing bibliography with indexes (supplement 282)

This bibliography lists 623 reports, articles, and other documents introduced into the NASA scientific and technical information system in Aug. 1992. The coverage includes documents on the engineering and theoretical aspects of design, construction, evaluation, testing, operation, and performance of aircraft (including aircraft engines) and associated components, equipment, and systems. It also includes research and development in aerodynamics, aeronautics, and ground support equipment for aeronautical vehicles

Idea, Form, Reality – the Implications of Natural Ventilation Strategies on public Buildings in Temperate Maritime Climates

Natural ventilation is one of the prime form givers in environmentally responsive architecture – in its detail and its architecturally charged form of stacks and voids. It facilitates our understanding of a response to natural systems – not just in how it responds visually to warm and cool air but also in the adaptive approach to thermal comfort. The purpose of this research is to investigate the impacts and implications of natural ventilation strategies for different typologies of public and commercial buildings. This is with the aim of attempting to define a vocabulary of ventilation techniques and details that are suited to particular categories of buildings within the temperate maritime climate of Europe. The effectiveness of the natural ventilation strategies are investigated through the parameters of energy usage, internal air quality, thermal comfort and operation. Following these, the different architectural responses to the physics of natural ventilation have been examined and in particular in the more detailed responses of differing building types. From this we can start to define appropriate strategies and the formal response of building types to natural ventilation

ReSCon '12, Research Student Conference: Book of Abstracts

The fifth SED Research Student Conference (ReSCon2012) was hosted over three days, 18-20 June 2012, in the Hamilton Centre at Brunel University. The conference consisted of 130 oral and 70 poster presentations, based on the high quality and diverse research being conducted within the School of Engineering and Design by postgraduate research students. The conference is held annually, and ReSCon plays a key role in contributing to research and innovations within the School

Cumulative index to NASA Tech Briefs, 1986-1990, volumes 10-14

Tech Briefs are short announcements of new technology derived from the R&D activities of the National Aeronautics and Space Administration. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This cumulative index of Tech Briefs contains abstracts and four indexes (subject, personal author, originating center, and Tech Brief number) and covers the period 1986 to 1990. The abstract section is organized by the following subject categories: electronic components and circuits, electronic systems, physical sciences, materials, computer programs, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Aeronautical engineering: A continuing bibliography with indexes (supplement 291)

This bibliography lists 757 reports, articles, and other documents introduced into the NASA scientific and technical information system in May. 1993. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

Advances in Theoretical and Computational Energy Optimization Processes

The paradigm in the design of all human activity that requires energy for its development must change from the past. We must change the processes of product manufacturing and functional services. This is necessary in order to mitigate the ecological footprint of man on the Earth, which cannot be considered as a resource with infinite capacities. To do this, every single process must be analyzed and modified, with the aim of decarbonising each production sector. This collection of articles has been assembled to provide ideas and new broad-spectrum contributions for these purposes

A World-Class University-Industry Consortium for Wind Energy Research, Education, and Workforce Development: Final Technical Report

During the two-year project period, the consortium members have developed control algorithms for enhancing the reliability of wind turbine components. The consortium members have developed advanced operation and planning tools for accommodating the high penetration of variable wind energy. The consortium members have developed extensive education and research programs for educating the stakeholders on critical issues related to the wind energy research and development. In summary, The Consortium procured one utility-grade wind unit and two small wind units. Specifically, the Consortium procured a 1.5MW GE wind unit by working with the world leading wind energy developer, Invenergy, which is headquartered in Chicago, in September 2010. The Consortium also installed advanced instrumentation on the turbine and performed relevant turbine reliability studies. The site for the wind unit is InvenergyÃÂÃÂÃÂâÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂs Grand Ridge wind farmin Illinois. The Consortium, by working with Viryd Technologies, installed an 8kW Viryd wind unit (the Lab Unit) at an engineering lab at IIT in September 2010 and an 8kW Viryd wind unit (the Field Unit) at the Stuart Field on IITÃÂÃÂÃÂâÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂs main campus in July 2011, and performed relevant turbine reliability studies. The operation of the Field Unit is also monitored by the Phasor Measurement Unit (PMU) in the nearby Stuart Building. The Consortium commemorated the installations at the July 20, 2011 ribbon-cutting ceremony. The ConsortiumÃÂÃÂÃÂâÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂs researches on turbine reliability included (1) Predictive Analytics to Improve Wind Turbine Reliability; (2) Improve Wind Turbine Power Output and Reduce Dynamic Stress Loading Through Advanced Wind Sensing Technology; (3) Use High Magnetic Density Turbine Generator as Non-rare Earth Power Dense Alternative; (4) Survivable Operation of Three Phase AC Drives in Wind Generator Systems; (5) Localization of Wind Turbine Noise Sources Using a Compact Microphone Array; (6) Wind Turbine Acoustics - Numerical Studies; and (7) Performance of Wind Turbines in Rainy Conditions. The ConsortiumÃÂÃÂÃÂâÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂs researches on wind integration included (1) Analysis of 2030 Large-Scale Wind Energy Integration in the Eastern Interconnection; (2) Large-scale Analysis of 2018 Wind Energy Integration in the Eastern U.S. Interconnection; (3) Integration of Non-dispatchable Resources in Electricity Markets; (4) Integration of Wind Unit with Microgrid. The ConsortiumÃÂÃÂÃÂâÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂs education and outreach activities on wind energy included (1) Wind Energy Training Facility Development; (2) Wind Energy Course Development; (3) Wind Energy Outreach

Bibliography of Lewis Research Center technical publications announced in 1992

This compilation of abstracts describes and indexes the technical reporting that resulted from the scientific and engineering work performed and managed by the Lewis Research Center in 1992. All the publications were announced in the 1992 issues of STAR (Scientific and Technical Aerospace Reports) and/or IAA (International Aerospace Abstracts). Included are research reports, journal articles, conference presentations, patents and patent applications, and theses