Minimization and Eulerian Formulation of Differential Geometry Based Nonpolar Multiscale Solvation Models

In this work, the existence of a global minimizer for the previous Lagrangian formulation of nonpolar solvation model proposed in [1] has been proved. One of the proofs involves a construction of a phase field model that converges to the Lagrangian formulation. Moreover, an Eulerian formulation of nonpolar solvation model is proposed and implemented under a similar parameterization scheme to that in [1]. By doing so, the connection, similarity and difference between the Eulerian formulation and its Lagrangian counterpart can be analyzed. It turns out that both of them have a great potential in solvation prediction for nonpolar molecules, while their decompositions of attractive and repulsive parts are different. That indicates a distinction between phase field models of solvation and our Eulerian formulation

Putting holes in holey geometry: Topology change for arbitrary surfaces

This paper presents a method for computing topology changes for triangle meshes in an interactive geometric modeling environment. Most triangle meshes in practice do not exhibit desirable geometric properties, so we develop a solution that is independent of standard assumptions and robust to geometric errors. Specifically, we provide the first method for topology change applicable to arbitrary non-solid, non-manifold, non-closed, self-intersecting surfaces. We prove that this new method for topology change produces the expected conventional results when applied to solid (closed, manifold, non-self-intersecting) surfaces---that is, we prove a backwards-compatibility property relative to prior work. Beyond solid surfaces, we present empirical evidence that our method remains tolerant to a variety of surface aberrations through the incorporation of a novel error correction scheme. Finally, we demonstrate how topology change applied to non-solid objects enables wholly new and useful behaviors

Feasibility study of an Integrated Program for Aerospace vehicle Design (IPAD). Volume 1B: Concise review

Reports on the design process, support of the design process, IPAD System design catalog of IPAD technical program elements, IPAD System development and operation, and IPAD benefits and impact are concisely reviewed. The approach used to define the design is described. Major activities performed during the product development cycle are identified. The computer system requirements necessary to support the design process are given as computational requirements of the host system, technical program elements and system features. The IPAD computer system design is presented as concepts, a functional description and an organizational diagram of its major components. The cost and schedules and a three phase plan for IPAD implementation are presented. The benefits and impact of IPAD technology are discussed

Modeling dendritic shapes - using path planning

Dendritic shapes are commonplace in the natural world such as trees, lichens, coral and lightning. Models of dendritic shapes are widely needed in many areas. Because of their branching fractal and erratic structures modeling dendritic shapes is a tricky task. Existing methods for modeling dendritic shapes are slow and complicated.In this thesis we present a procedural algorithm of using path planning to model dendritic shapes. We generate a dendrite by finding the least-cost paths from multiple endpoints to a common generator and use the dendrite to build the geometric model. With the control handles of endpoint placement, fractal shape, edge weights distribution and path width, we create different shapes of dendrites that simulate different kinds of dendritic shapes very well. Compared with some existing methods, our algorithm is fast and simple

DEVELOPMENT OF AN ADVANCED HEAT EXCHANGER MODEL FOR STEADY STATE AND FROSTING CONDITIONS

Air-to-refrigerant fin-and-tube heat exchangers are a key component in the heating, air conditioning and refrigeration industry. Considering their dominance, the industry has focused immensely on employing computer modeling in their design and development. Recently, advances in manufacturing capabilities, heat exchanger technology coupled with the move towards new environment-friendly refrigerants provide unprecedented challenges for designers and opportunities for researchers. In addition, the field of Computational Fluid Dynamics (CFD) has assumed a greater role in the design of heat exchangers. This research presents the development of an advanced heat exchanger model and design tool which aims to provide greater accuracy, design flexibility and unparalleled capabilities compared to existing heat exchanger models. The heat exchanger model developed here achieves the following. * Account for tube-to-tube conduction along fins, which is known to degrade the performance of heat exchangers, especially in carbon dioxide gas coolers * Study and develop heat exchangers with arbitrary fin sheets, which meet performance as well as packaging goals with minimal consumption of resources * Allow engineers to integrate CFD results for air flow through a heat exchanger, which the modeling tool employs to develop its air propagation sequence leading to improved accuracy over existing models which assume normal air flow propagation * Function in a quasi-steady state mode for the purpose of simulating frost accumulation and growth on heat exchangers, and completely simulate local heat transfer degradation, as well as blockage of flow passage on air side Additionally, the heat exchanger model was used to investigate gains that are enabled due to the presence of cut fins in carbon dioxide gas coolers and develop design guidelines for engineers. Finally, this dissertation analyzes the implications of minimum entropy generation on heat exchanger performance criteria of heat capacity and pressure drop, as well as evaluates the ability of entropy generation minimization as a design objective. This also serves as the first step toward an expert knowledge-based system for guiding engineers towards better designs, during the process of heat exchanger design

Simulating surface water and groundwater flow dynamics in tile-drained catchments

Pratique agricole répandue dans les champs sujets à l’accumulation d’eau en surface, le drainage souterrain améliore la productivité des cultures et réduit les risques de stagnation d’eau. La contribution significative du drainage sur les bilans d’eau à l’échelle de bassins versants, et sur les problèmes de contamination dus à l’épandage d’engrais et de fertilisant, a régulièrement été soulignée. Les écoulements d’eau souterraine associés au drainage étant souvent inconnus, leur représentation par modélisation numérique reste un défi majeur. Avant de considérer le transport d’espèces chimiques ou de sédiments, il est essentiel de simuler correctement les écoulements d’eau souterraine en milieu drainé. Dans cette perspective, le modèle HydroGeoSphere a été appliqué à deux bassins versants agricoles drainés du Danemark. Un modèle de référence a été développé à l’échelle d’une parcelle dans le bassin versant de Lillebæk pour tester une série de concepts de drainage dans une zone drainée de 3.5 ha. Le but était de définir une méthode de modélisation adaptée aux réseaux de drainage complexes à grande échelle. Les simulations ont indiqué qu’une simplification du réseau de drainage ou que l’utilisation d’un milieu équivalent sont donc des options appropriées pour éviter les maillages hautement discrétisés. Le calage des modèles reste cependant nécessaire. Afin de simuler les variations saisonnières des écoulements de drainage, un modèle a ensuite été créé à l’échelle du bassin versant de Fensholt, couvrant 6 km2 et comprenant deux réseaux de drainage complexes. Ces derniers ont été simplifiés en gardant les drains collecteurs principaux, comme suggéré par l’étude de Lillebæk. Un calage du modèle par rapport aux débits de drainage a été réalisé : les dynamiques d’écoulement ont été correctement simulées, avec une faible erreur de volumes cumulatifs drainés par rapport aux observations. Le cas de Fensholt a permis de valider les conclusions des tests de Lillebæk, ces résultats ouvrant des perspectives de modélisation du drainage lié à des questions de transport.Tile drainage is a common agricultural management practice in plots prone to ponding issues. Drainage enhances crop productivity and reduces waterlogging risks. Studies over the last few decades have highlighted the significant contribution of subsurface drainage to catchments water balance and contamination issues related to manure or fertilizer application at the soil surface. Groundwater flow patterns associated with drainage are often unknown and their representation in numerical models, although powerful analysis tools, is still a major challenge. Before considering chemical species or sediment transport, an accurate water flow simulation is essential. The integrated fully-coupled hydrological HydroGeoSphere code was applied to two highly tile-drained agricultural catchments of Denmark (Lillebæk and Fensholt) in the present work. A first model was developed at the field scale from the Lillebæk catchment. A reference model was set and various drainage concepts and boundary conditions were tested in a 3.5 ha tile-drained area to find a suitable option in terms of model performance and computing time for larger scale modeling of complex drainage networks. Simulations suggested that a simplification of the geometry of the drainage network or using an equivalent-medium layer are suitable options for avoiding highly discretized meshes, but further model calibration is required. A catchment scale model was subsequently built in Fensholt, covering 6 km2 and including two complex drainage networks. The aim was to perform a year-round simulation accounting for variations in seasonal drainage flow. Both networks were simplified with the main collecting drains kept in the model, as suggested by the Lillebæk study. Calibration against hourly measured drainage discharge data was performed resulting in a good model performance. Drainage flow and flow dynamics were accurately simulated, with low cumulative error in drainage volume. The Fensholt case validated the Lillebæk test conclusions, allowing for further drainage modeling linked with transport issues

Topographic reconstruction from radar imagery

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1988.Includes bibliographical references.by Joseph R. Matarese.M.S

Dissecting multiple sequence alignment methods : the analysis, design and development of generic multiple sequence alignment components in SeqAn

Multiple sequence alignments are an indispensable tool in bioinformatics. Many applications rely on accurate multiple alignments, including protein structure prediction, phylogeny and the modeling of binding sites. In this thesis we dissected and analyzed the crucial algorithms and data structures required to construct such a multiple alignment. Based upon that dissection, we present a novel graph-based multiple sequence alignment program and a new method for multi-read alignments occurring in assembly projects. The advantage of the graph-based alignment is that a single vertex can represent a single character, a large segment or even an abstract entity such as a gene. This gives rise to the opportunity to apply the consistencybased progressive alignment paradigm to alignments of genomic sequences. The proposed multi-read alignment method outperforms similar methods in terms of alignment quality and it is apparently one of the first methods that can readily be used for insert sequencing. An important aspect of this thesis was the design, the development and the integration of the essential multiple sequence alignment components in the SeqAn library. SeqAn is a software library for sequence analysis that provides the core algorithmic components required to analyze large-scale sequence data. SeqAn aims at bridging the current gap between algorithm theory and available practical implementations in bioinformatics. Hence, we always describe in conjunction to the theoretical development of the methods, the actual implementation of the data structures and algorithms in order to strengthen the use of SeqAn as an experimental platform for rapidly developing and testing applications. All presented methods are part of the open source SeqAn library that can be downloaded from our website, www.seqan.de