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CiteSeerX Scientific Literature Digital Library and Search Engine (4,211,304 recursos)
CiteSeerX is a scientific literature digital library and search engine that focuses primarily on the literature in computer and information science. CiteSeerx aims to improve the dissemination of scientific literature and to provide improvements in functionality, usability, availability, cost, comprehensiveness, efficiency, and timeliness in the access of scientific and scholarly knowledge

Mostrando recursos 1 - 20 de 4,124,017

1. Adaptive paired comparison design - Mark E. Glickman; Shane T. Jensen
An important aspect of paired comparison experiments is the decision of how to form pairs in advance of collecting data. A weakness of typical paired comparison experimental designs is the di culty in incorporating prior information, which can be particularly relevant for the design of tournament schedules for players of games and sports. Pairing methods that make use of prior information are often ad hoc algorithms with little or no formal basis. The problem of pairing objects can be formalized as a Bayesian optimal design. Assuming a linear paired comparison model for outcomes, we develop a pairing method that maximizes...

2. Adaptivity in Space and Time for Reaction-Diffusion Systems in Electrocardiology - P. Colli Franzone; P. Deuflhard; B. Erdmann; J. Lang; Luca F. Pavarino
Adaptive numerical methods in space and time are introduced and studied for multiscale cardiac reaction-diffusion models in three dimensions. The evolution of a complete heartbeat, from the excitation to the recovery phase, is simulated with both the anisotropic Bidomain and Monodomain models, coupled with either a variant of the simple FitzHugh-Nagumo model or the more complex phase-I Luo-Rudy ionic model. The simulations are performed with the kardos library, that employs adaptive finite elements in space and adaptive linearly implicit methods in time. The numerical results show that this adaptive method successfully solves these complex cardiac reaction-diffusion models on three-dimensional domains...

3. A framework for automatically recovering object shape, reflectance and light sources from calibrated images - Bruno Mercier; Daniel Meneveaux; Alain Fournier
In this paper, we present a complete framework for recovering an object shape, estimating its reflectance properties and light sources from a set of images. The whole process is performed automatically. We use the shape from silhouette approach proposed by R. Szeliski in [40] combined with image pixels for reconstructing a triangular mesh according to the marching cubes algorithm. A classification process identifies regions of the object having the same appearance. For each region, a single point or directional light source is detected. Therefore, we use specular lobes, lambertian regions of the surface or specular highlights seen on images. An...

4. Two preconditioners based on the multi-level splitting of finite element spaces - Harry Yserentant

5. Algebraic multigrid methods for constrained linear systems with applications to contact problems in solid mechanics - Mark F. Adams
This paper develops a general framework for applying algebraic multigrid techniques to constrained systems of linear algebraic equations that arise in applications with discretized PDEs. We discuss constraint coarsening strategies for constructing multigrid coarse grid spaces and several classes of multigrid smoothers for these systems. The potential of these methods is investigated with their application to contact problems in solid mechanics.

6. Optimization Software Packages - Stephen J. Wright
We discuss software packages for solving optimization problems, focusing on fundamental software that assumes that the problem has already been formulated in mathematical terms. Such packages can be used directly in many applications, linked to modeling languages or to graphical user interfaces, or embedded in complex software systems such as logistics and supply chain management systems.

7. Reflectance from Images: A Model-Based Approach for Human Faces - Martin Fuchs; Volker Blanz; Hendrik Lensch; Hans-peter Seidel
In this paper, we present an image-based framework that acquires the reflectance properties of a human face. A range scan of the face is not required. Based on a morphable face model, the system estimates the 3D shape, and establishes point-to-point correspondence across images taken from different viewpoints, and across different individuals' faces. This pro-vides a common parameterization of all reconstructed surfaces that can be used to compare and transfer BRDF data between different faces. Shape estimation from images compensates deformations of the face during the measurement process, such as facial expressions. In the common parameterization, regions of homogeneous materials...

8. Leapfrog Triejoin: A Simple, Worst-Case Optimal Join Algorithm - Todd L. Veldhuizen
Recent years have seen exciting developments in join algorithms. In 2008, Atserias, Grohe and Marx (henceforth AGM) proved a tight bound on the maximum result size of a full conjunctive query, given constraints on the input relation sizes. In 2012, Ngo, Porat, Re and Rudra (henceforth NPRR) devised a join algorithm with worst-case running time proportional to the AGM bound [8]. Our commercial database system LogicBlox employs a novel join algorithm, leapfrog triejoin, which compared conspicuously well to the NPRR algorithm in preliminary benchmarks. This spurred us to analyze the complexity of leapfrog triejoin. In this paper we establish that...

9. A novel efficient model for the power flow analysis of power systems - Amir Safdarian; Mahmud Fotuhi-firuzabad; Farrokh Aminifar
The overall system status calculated by power flow analysis is the most basic information used for all decisions taken by power system operators and planners. While conventional AC power flow solutions are computationally tractable, approximate DC models are employed in many applications, such as optimal power flow studies and unit commitment problems, mainly due to the linear nature of DC models. These models do not provide any information on the reactive power and voltage magnitude quantities and occasionally inaccurate results of the active power values. This paper presents an efficient power flow approach compromising both the conflicting aspects of speed...

10. Usage of Abstract Features in Semantic Sentiment Analysis - Mohammed Almashraee; Kia Teymourian; Dagmar Monett-diaz; Adrian Paschke
Feature-based sentiment analysis can be realized on different types of object features. Some of these features might be about technical aspects of the objects and some others might be application-oriented features. The application-oriented features are more abstract features and can be of interest to the broad number of people than only the technical experts of specific products. In this paper, we propose an approach for extraction of abstract object features from a set of sub-features. In our approach we use a knowledge base about the application domain to extract related sub-features of high-level abstract features. On the basis of such...

11. Photometric Object Modeling -- Rendering from a . . . - Ko Nishino
For some time, rendering photorealistic synthetic images from observations of real objects has been a major research topic in the computer vision and computer graphics communities. An extensive amount of work in this research area has lead to a few representative schools: image-based rendering, inverse rendering and 3D photography. However, each of these methods still suffers from several drawbacks, such as massive data storage, constraints on applicable objects, restrictive scenarios on application, etc. To overcome these problems, we propose twomethods. The first method, Eigen-Texture Rendering, handles the appearance variation of the target object on its own 2D surface, enabling effective...

12. Exploiting Domain Knowledge in Aspect Extraction - Zhiyuan Chen; Arjun Mukherjee; Bing Liu; Meichun Hsu; Malu Castellanos; Riddhiman Ghosh
Aspect extraction is one of the key tasks in sentiment analysis. In recent years, statistical models have been used for the task. However, such models without any domain knowledge often produce aspects that are not interpretable in applications. To tackle the issue, some knowledge-based topic models have been proposed, which allow the user to input some prior domain knowledge to generate coherent aspects. However, existing knowledge-based topic models have several major shortcom-ings, e.g., little work has been done to incorporate the cannot-link type of knowledge or to automatically adjust the number of topics based on domain knowledge. This paper proposes...

13. Three–Dimensional Fully Adaptive Solution of Thermo–Diffusive Flame Propagation Problems - Jens Lang; Bodo Erdmann; Rainer Roitzsch
In this paper we present a self–adaptive finite element method to solve flame propagation problems in 3D. An implicit time integrator of Rosenbrock type is coupled with a multilevel approach in space. The proposed method is applied to an unsteady thermo–diffusive combustion model to demonstrate its potential for the solution of complicated problems.

14. Adaptive Time–Space Discretization for Combustion Problems - Jens Lang; Bodo Erdmann; Rainer Roitzsch
We present a self–adaptive finite element method to solve combustion problems in 1D, 2D, and 3D. An implicit time integrator of Rosenbrock type is coupled with a multilevel approach in space. A posteriori error estimates are obtained by constructing locally higher order solutions involving all variables of the problem. Adaptive strategies such as step size control, spatial refinement and coarsening allow us to get economically an accurate solution. Various examples are presented to demonstrate practical applications of the proposed method.

15. Homogeneous Penalizers and Constraints in Convex Image Restoration - R. Ciak, et al.
Recently convex optimization models were successfully applied for solving various prob-lems in image analysis and restoration. In this paper, we are interested in relations between convex constrained optimization problems of the form argmin{Φ(x) subject to Ψ(x) ≤ τ} and their penalized counterparts argmin{Φ(x) + λΨ(x)}. We recall general results on the topic by the help of an epigraphical projection. Then we deal with the special setting Ψ: = ‖L · ‖ with L ∈ Rm,n and Φ: = ϕ(H ·), where H ∈ Rn,n and ϕ: Rn → R∪{+∞} meet certain requirements which are often fulfilled in image process-ing models....

16. Analysis of Chess Game Outcomes - n.n.

17. Iterative solvers within sequences of large linear systems in non-linear structural mechanics - Stefan Hartmann; Jurjen Duintjer Tebbens; Karsten J. Quint; Andreas Meister

In this work higher-order methods for integrating the three-dimensional incompressible Navier-Stokes equations are proposed. The numerical solution is achieved by using linearly implicit one-step methods up to third order in time coupled with up to third order stable finite element discretizations in space. These orders of convergence are demon-strated by comparing the numerical solution with exact Navier-Stokes solutions. Finally, we present benchmark computations for flow around a cylinder.

19. Affine Conjugate Adaptive Newton Methods for nonlinear elastomechanics - Martin Weiser; Peter Deuflhard; Bodo Erdmann

20. Linear convergence of an interior point method for linear control constrained optimal control problems - Martin Weiser

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