Topological Decompositions for 3D Non-manifold Simplicial Shapes

Modeling and understanding complex non-manifold shapes is a key issue in several applications including form-feature identification in CAD/CAE, and shape recognition for Web searching. Geometric shapes are commonly discretized as simplicial 2- or 3-complexes embedded in the 3D Euclidean space. The topological structure of a non-manifold simplicial shape can be analyzed through its decomposition into a collection of components with simpler topology. The granularity of the decomposition depends on the combinatorial complexity of the components. In this paper, we present topological tools for structural analysis of three-dimensional non-manifold shapes. This analysis is based on a topological decomposition at two different levels. We discuss the topological properties of the components at each level, and we present algorithms for computing such decompositions. We investigate the relations among the components, and propose a graph-based representation for such relations

A dimension-independent simplicial data structure for non-manifold shapes

We consider the problem of representing and manipulating non-manifold multi-dimensional shapes, discretized as $d$-dimensional simplicial Euclidean complexes, for modeling finite element meshes derived from CAD models. We propose a dimension-independent data structure for simplicial complexes, that we call the {\em Incidence Simplicial (IS)} data structure. The IS data structure is scalable to manifold complexes, and supports efficient traversal and update algorithms for performing topological modifications, such as hole removal or dimension reduction. It has the same expressive power and performances as the incidence graph, commonly used for dimension-independent representation of simplicial and cell complexes, but it is much more compact. We present efficient algorithms for traversing, generating and updating a simplicial complex described as an IS data structure. We compare the IS data structure with dimension-independent and dimension-specific representations for simplicial complexes. Finally, we briefly discuss two applications that the IS data structure supports, namely decomposition of non-manifold objects for effective geometric reasoning, and multi-resolution modeling of non-manifold multi-dimensional shapes

Constraint-Enabled Design Information Representation for Mechanical Products Over the Internet

Global economy has made manufacturing industry become more distributed than ever before. Product design requires more involvement from various technical disciplines at different locations. In such a geographically and temporally distributed environment, efficient and effective collaboration on design is vital to maintain product quality and organizational competency. Interoperability of design information is one of major barriers for collaborative design. Current standard CAD data formats do not support design collaboration effectively in terms of design information and knowledge capturing, exchange, and integration within the design cycle. Multidisciplinary design constraints cannot be represented and transferred among different groups, and design information cannot be integrated efficiently within a distributed environment. Uncertainty of specification cannot be modeled at early design stages, while constraints for optimization are not embedded in design data. In this work, a design information model, Universal Linkage model, is developed to represent design related information for mechanical products in a distributed form. It incorporates geometric and non-geometric constraints with traditional geometry and topology elements, thus allows more design knowledge sharing in collaborative design. Segments of design data are linked and integrated into a complete product model, thus support lean design information capturing, storage, and query. The model is represented by Directed Hyper Graph and Product Markup Language to preserve extensibility and openness. Incorporating robustness consideration, an Interval Geometric Modeling scheme is presented, in which numerical parameters are represented by interval values. This scheme is able to capture uncertainty and inexactness of design and reduces the chances of conflict in constraint imposition. It provides a unified constraint representation for the process of conceptual design, detailed design, and design optimization. Corresponding interval constraint solving methods are studied

A maximum margin dynamic model with its application to brain signal analysis

Ph.DDOCTOR OF PHILOSOPH

Evaluation of computer aided software as a space analysis tool for outfit unit design and planning

http://deepblue.lib.umich.edu/bitstream/2027.42/1123/2/89009.0001.001.pd

Modeling of shell forming by line heating

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2000.Includes bibliographical references (leaves 172-179).Metal forming by a moving heat source is an efficient and economical method for forming flat metal plates into doubly curved shapes. This thesis proposes an FEM model for three dimensional thermo-mechanical simulation of the process of shell forming by line heating. Since the heat flux is focused on a small area under the heat source, a rezoning technique is developed to reduce computation time in three-dimensional numerical simulation. This involves dynamic remeshing of the metal plate so that the area directly under the heat source is densely meshed while other areas are sparsely meshed. A simplified model is also developed which is based on semi-analytical thermal analysis and idealization of plastic zone during line heating. This simplified model is useful in real-time control of the forming process since the computation time can be greatly reduced. The two thermo-mechanical models lead to a better understanding of the line heating mechanism and more accurate and efficient prediction of the deformation of metal plates. Based on these two models, parametric studies of the edge effects, heat input, heat source velocity, spot size, heat loss coefficients, etc. are performed, and nondimensional parameters which control the bending angle are derived. Finally, an algorithm for surface development for heating path planning is developed. This algorithm minimizes the strains from the doubly curved surface to its planar development. Compared with conventional surface development methods, this algorithm takes into account the characteristics of the process of forming by line heating. This surface development algorithm lays the basis for heating path determination. Based on the developed algorithms and models, we will be able to not only determine the heating paths, but also determine the heating conditions which are necessary to form an initial flat plate into a doubly curved plate. These are critical for automation of the metal forming process.by Guoxin Yu.Ph.D

Phylogenetic exploration of mating system evolution in the eastern North American leiobunine harvestmen (Opiliones: Sclerosomatidae)

Understanding the basis for the vast diversity in reproductive structures found within the animal kingdom is a perennial issue in evolutionary biology. Meanwhile, taxonomists have long capitalized on the substantial genital diversity in the eastern North American leiobunine harvestmen for identifying and delimiting species, but no attempts have been made to explore the functional or evolutionary significance of this variety. Past discussion of the evolution of reproductive heterogeneity attributes genitalic diversification to female preferences, although recent work has also emphasized the (potentially competing) importance of intersexual conflict leading to sexually antagonistic coevolution. Here I test the overarching support for diversification of reproductive structures in leiobunine harvestmen via female choice and sexual conflict mechanisms of sexual selection. My dissertation work consisted of 1) reconstructing the phylogeny of eastern North American leiobunine harvestmen using molecular characters, 2) mapping and simulating relevant discrete morphological features, and 3), using biomechanical and kinetic reproductive data to test whether the direction of evolutionary change in reproductive characters within and between sexes is consistent with increasing sexual antagonism through evolutionary time via a comparative approach. I found support for the monophyly of the eastern North American leiobunine harvestmen, as well as evidence for an evolutionary transition from enticement-based mating to conflict-based systems. My novel uses of phylogenetic comparative methods to quantify mating systems demonstrate that leiobunine species form a continuum of reproductive diversity ranging from specialization in female enticement to precopulatory antagonistic contexts, with correlations between male and female discrete and continuous traits, suggesting long-term sexual coevolution has occurred. I conclude that mating system evolution has occurred in the leiobunine harvestmen, with sexual selection as its ultimate driver, and I offer hypotheses as to the origins of sexual conflict in these temperate lineages

Journal Usage by Subject for Fiscal Year 2010

Journal holdings for the University Libraries are listed alphabetically by subject than authority title. Usage statistics for the fiscal year are included along with a cost per use where available. The information is taken from each vendor and incorporated in Serials Solutions 360 Counter

Application des cartes combinatoires à la modélisation géométrique et sémantique des bâtiments

3D building models are widely used in the civil engineering industry. While the models are needed by several applications, such as architectural representations and simulation processes, they often lack of information that are of major importance for the consistency of the calculations. The original models are then often rebuilt in the way that fits better to the intended applications. To overcome this drawback, we introduce a framework allowing to enrich a 3D model of a building presenting just a geometry, in a way more interoperable model, by adding to it topological and semantic information. A cellular subdivision of the building space is first performed relying on its geometry, then the topological relationships between the cells are explicitely defined. Semantic labels are then attributed to the identified components based on the topology and defined heuristic rules. A 3D combinatorial map data structure (3-map) is used to handle the reconstructed information. From the enriched model we show how to extract applications-driven information allowing to perform acoustic simulation and indoor ray tracing navigation. The approach stands as a bridge between the modeling approaches and the applications in building analysis using the model. It is fully automatic and present interesting results on several types of building modelsLes modèles 3D de bâtiment sont largement utilisés dans l'industrie de la construction et sont nécessités par plusieurs applications telles que la représentation architecturale et les processus de simulation. Malheureusement, ces modèles manquent souvent d'informations d'une importance majeure pour permettre d'effectuer des opérations d'analyse et de calcul. Les modèles originaux sont alors souvent reconstruits par les différents acteurs qui les utilisent afin de les rendre plus adaptés à leur besoins. Dans le but de pallier ce problème, nous introduisons une approche permettant d'enrichir un modèle 3D de bâtiment et le rendre beaucoup plus interopérable. À partir de l'information géométrique seulement, nous rajoutons au modèle des informations topologiques et sémantiques. Une subdivision cellulaire de l'espace occupé par le bâtiment est d'abord effectuée en se basant sur sa géométrie, puis les relations topologiques entre les cellules sont reconstruites et explicitement définies. Des étiquettes sémantiques sont ensuite attribuées aux composants identifiés du bâtiment à l'aide de la topologie reconstruite et des règles heuristiques prédéfinies. Une structure de données topologique appelée carte combinatoire 3D (3-carte) est utilisée comme une base solide pour la mise au point des opération de reconstruction et le traitement des informations reconstruites. À partir du modèle enrichi, nous montrons comment extraire des données pour des applications dédiées, par exemple la simulation acoustique et lancer de rayon pour la navigation intérieure. Notre méthode se présente comme un pont entre les approches de modélisation et les applications d'analyse du bâtiment qui utilisent ces modèles. Il est entièrement automatique et présente des résultats intéressants sur plusieurs types de modèle

2005 New York State Statistical Yearbook

[Excerpt] This is the thirtieth edition of the New York State Statistical Yearbook, which the Nelson A. Rockefeller Institute of Government publishes annually in cooperation with the Office of the Governor and the New York State Division of the Budget. For information about other New York state and local activities of the Institute, see our website at www.rockinst.org