Polygon mesh is among the most common datastructures used for representing objects in computer graphics. Unfortunately, a polygon mesh does not capture high-level structures, unlike a hierarchical model. In general, ...
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ISBN:
(纸本)0769520847
Polygon mesh is among the most common datastructures used for representing objects in computer graphics. Unfortunately, a polygon mesh does not capture high-level structures, unlike a hierarchical model. In general, high-level abstractions are useful for managing data in applications. In this paper, we present a method for decomposing an object represented in polygon meshes into components by means of critical points. the method consists of steps to define the root vertex of the object, define a function on the polygon meshes, compute the geodesic tree and critical points, decide the decomposition order, and extract components using backwards flooding. We have implemented the method. the preliminary results show that it works effectively and efficiently. the decomposition results can be useful for applications such as 3D model retrieval and morphing.
P2P overlays offer a convenient way to host an infrastructure that can scale to the size of the Internet and yet be manageable. Current proposals, however, do not offer support for structuring data, other than assumin...
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ISBN:
(纸本)0769521185
P2P overlays offer a convenient way to host an infrastructure that can scale to the size of the Internet and yet be manageable. Current proposals, however, do not offer support for structuring data, other than assuming a distributed hash table. In reality, both applications and users typically organize data in a structured form. One such popular structure is the tree as employed in a file system, and a database. A naive approach such as hashing the pathname not only ignores locality in important operations such as file/directory lookup, but also results in uncontrollable, massive object relocations when rename on a path component occur. In this paper, we investigate policies and strategies that place a tree onto the flat storage space of P2P systems. We found that, in general, there exists a tradeoff between lookup performance and balanced storage utilization, and attempt to balance these two requirements calls for an intelligent placement decision.
Scheduling is one of the most successful application areas of constraint programming mainly thanks to special global constraints designed to model resource restrictions. Among these global constraints, edge-finding fi...
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Biased semiconductor quantum well cascade structures, as are nowadays used in intersubband infrared photodetectors and lasers, are well known to be susceptible to the formation of electric field domains. the homogeneo...
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Biased semiconductor quantum well cascade structures, as are nowadays used in intersubband infrared photodetectors and lasers, are well known to be susceptible to the formation of electric field domains. the homogeneous electric field in a structure is broken, due to charge redistribution over individual wells and the appearance of the associated space-charge contribution to the potential. In this work we consider the formation of stationary periodic domains in p-type Si/SiGe cascade structures. Hole transport is described via scattering between quantized subbands in subsequent wells, as calculated using the 6/spl times/6 k.p method which accounts for the full anisotropy of heavy hole and light hole subbands. the scattering mechanisms taken into account are deformation potential (acoustic and optical phonons), alloy disorder, and carrier-carrier scattering. In order to find the possibility of domain formation the hole scattering rates between all pairs of states in subsequent wells in a homogeneous cascade are calculated, as a function of the electric field, taking the carrier heating (thermal self-consistency) into account. these are then used (via interpolation) to solve a system of rate equations for the subband populations in each quantum well, coupled withthe discretized Poisson equation. In order to avoid use of contact boundary conditions, for which no experimental data is presently available, we use periodic boundary conditions, in which the electric field distribution in a long homogeneous cascade is assumed to break into an arbitrary number of periodic segments. this is a generalization of the period-doubling model described in (Ryzhii et al. (2000).
Modeling plays a central role in system engineering. It significantly reduces costs and efforts in the design by providing developers with means for cheaper and more relevant experimentations. So, design choices can b...
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ISBN:
(纸本)0769519172
Modeling plays a central role in system engineering. It significantly reduces costs and efforts in the design by providing developers with means for cheaper and more relevant experimentations. So, design choices can be assessed earlier the use of a formalism, such as the synchronous language SIGNAL which relies on solid mathematical foundations for the modeling, allows validation. this is the aim of the methodology defined for the design of embedded systems where emphasis is put on formal techniques for verification, analysis, and code generation. this paper mainly focuses on the modeling of architecture components using SIGNAL. For illustration, we consider the modeling of a bounded FIFO queue, which is intended to be used for communication protocols. We bring out the capabilities of SIGNAL to allow specifications in an elegant way, and we check few elementary properties on the resulting model for correctness.
this article presents a hybrid. software/hardware architecture for commander's decision support in tactical operations. the architecture builds on the symbolic, object-oriented visualization software called Advanc...
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ISBN:
(纸本)0769519172
this article presents a hybrid. software/hardware architecture for commander's decision support in tactical operations. the architecture builds on the symbolic, object-oriented visualization software called Advanced Tactical Architecture for Combat Knowledge System (ATACKS). the extension discussed here is the design of a real-time robot agent layer that interacts wirelessly with ATACKS. this layer enacts decisions made by software agents (wargamers), continuously relays the execution states back to ATACKS, and updates its actions as advocated by replanning algorithms. the software layer is briefly described followed by the specification of the real-time requirements for the robotic architecture. the design and implementation are given with a small example that illustrates the hybrid system's operation.
this paper examines the performance of vertex algorithms used for B-tagging in t (t) over bar events at CDF during Run 1 at the Fermilab (p) over barp collider and discusses the main principles that led to the most dr...
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this paper examines the performance of vertex algorithms used for B-tagging in t (t) over bar events at CDF during Run 1 at the Fermilab (p) over barp collider and discusses the main principles that led to the most dramatic improvements in performance. Some further implications for algorithm and detector design are also discussed. (C) 2002 Elsevier Science B.V. All rights reserved.
this paper examines the performance of vertex algorithms used for B-tagging in t (t) over bar events at CDF during Run 1 at the Fermilab (p) over barp collider and discusses the main principles that led to the most dr...
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this paper examines the performance of vertex algorithms used for B-tagging in t (t) over bar events at CDF during Run 1 at the Fermilab (p) over barp collider and discusses the main principles that led to the most dramatic improvements in performance. Some further implications for algorithm and detector design are also discussed. (C) 2002 Elsevier Science B.V. All rights reserved.
In this paper we study proximity structures like Delauney triangulations based on geometric graphs, i.e. graphs which are subgraphs of the complete geometric graph. Given an arbitrary geometric graph G, we define seve...
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