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301.
Natashia Boland Barry D. Hughes Liam T.G. Merlot Peter J. Stuckey 《Computers & Operations Research》2008
The most complete form of academic timetabling problem is the population and course timetabling problem. In this problem, there may be multiple classes of each subject, and the decision on which students are to constitute each class is made in concert with the decision on the timetable for each class. In order to solve this problem, it is normally simplified or decomposed in some fashion. One simplification commonly used in practice is known as blocking: it is assumed that the classes can be partitioned into sets of classes (or blocks) that will be timetabled in parallel. This restricts clashing to occur only between classes in the same block, and essentially removes the timetabling aspect of the problem, which can be carried out once the blocks are constituted and the classes populated. The problem of constituting the blocks and populating the classes, known as the course blocking and population problem, is nevertheless a challenging problem, and provides the focus of this paper. We demonstrate, using data provided by a local high school, that integer linear programming approaches can solve the problem in a matter of seconds. Key features include remodelling to remove symmetry caused by students with identical subject selection, and the observation that in practice, only integrality of the block composition variables needs to be enforced; the class population aspects of the model have strong integrality properties. 相似文献
302.
This paper addresses the problem of minimizing the expected cost of locating a number of single product facilities and allocating uncertain customer demand to these facilities. The total costs consist of two components: firstly linear transportation cost and secondly the costs of investing in a facility as well as maintaining and operating it. These facility costs are general and non-linear in shape and could express both changing economies of scale and diseconomies of scale. We formulate the problem as a two-stage stochastic programming model where both demand and short-run costs may be uncertain at the investment time. We use a solution method based on Lagrangean relaxation, and show computational results for a slaughterhouse location case from the Norwegian meat industry. 相似文献
303.
Todd Zickler Satya P. Mallick David J. Kriegman Peter N. Belhumeur 《International Journal of Computer Vision》2008,79(1):13-30
Complex reflectance phenomena such as specular reflections confound many vision problems since they produce image ‘features’
that do not correspond directly to intrinsic surface properties such as shape and spectral reflectance. A common approach
to mitigate these effects is to explore functions of an image that are invariant to these photometric events. In this paper
we describe a class of such invariants that result from exploiting color information in images of dichromatic surfaces. These
invariants are derived from illuminant-dependent ‘subspaces’ of RGB color space, and they enable the application of Lambertian-based
vision techniques to a broad class of specular, non-Lambertian scenes. Using implementations of recent algorithms taken from
the literature, we demonstrate the practical utility of these invariants for a wide variety of applications, including stereo,
shape from shading, photometric stereo, material-based segmentation, and motion estimation. 相似文献
304.
Nonparametric Bayesian Image Segmentation 总被引:1,自引:0,他引:1
Image segmentation algorithms partition the set of pixels of an image into a specific number of different, spatially homogeneous
groups. We propose a nonparametric Bayesian model for histogram clustering which automatically determines the number of segments
when spatial smoothness constraints on the class assignments are enforced by a Markov Random Field. A Dirichlet process prior
controls the level of resolution which corresponds to the number of clusters in data with a unique cluster structure. The resulting posterior is efficiently
sampled by a variant of a conjugate-case sampling algorithm for Dirichlet process mixture models. Experimental results are
provided for real-world gray value images, synthetic aperture radar images and magnetic resonance imaging data. 相似文献
305.
Michael Carl Maite Melero Toni Badia Vincent Vandeghinste Peter Dirix Ineke Schuurman Stella Markantonatou Sokratis Sofianopoulos Marina Vassiliou Olga Yannoutsou 《Machine Translation》2008,22(1-2):67-99
METIS-II was an EU-FET MT project running from October 2004 to September 2007, which aimed at translating free text input without resorting to parallel corpora. The idea was to use “basic” linguistic tools and representations and to link them with patterns and statistics from the monolingual target-language corpus. The METIS-II project has four partners, translating from their “home” languages Greek, Dutch, German, and Spanish into English. The paper outlines the basic ideas of the project, their implementation, the resources used, and the results obtained. It also gives examples of how METIS-II has continued beyond its lifetime and the original scope of the project. On the basis of the results and experiences obtained, we believe that the approach is promising and offers the potential for development in various directions. 相似文献
306.
Classification of Fuzzy Mathematical Morphologies Based on Concepts of Inclusion Measure and Duality
Mathematical morphology was originally conceived as a set theoretic approach for the processing of binary images. Extensions
of classical binary morphology to gray-scale morphology include approaches based on fuzzy set theory. This paper discusses
and compares several well-known and new approaches towards gray-scale and fuzzy mathematical morphology. We show in particular
that a certain approach to fuzzy mathematical morphology ultimately depends on the choice of a fuzzy inclusion measure and
on a notion of duality. This fact gives rise to a clearly defined scheme for classifying fuzzy mathematical morphologies.
The umbra and the level set approach, an extension of the threshold approach to gray-scale mathematical morphology, can also
be embedded in this scheme since they can be identified with certain fuzzy approaches.
相似文献
Marcos Eduardo ValleEmail: |
307.
Peter Martin 《自动化博览》2009,26(10):40-43
本文介绍了世界上第一个企业控制系统(ECS)——英维思的InFusion平台,它为工厂企业提供一个通用的计算空间,能够在各种智能自动化技术或系统上提供最先进的互操作能力,同时大幅降低成本,从而显著提升业务绩效。 相似文献
308.
Chen Huanhuan Ti o Peter Yao Xin 《Knowledge and Data Engineering, IEEE Transactions on》2009,21(7):999-1013
An ensemble is a group of learners that work together as a committee to solve a problem. The existing ensemble learning algorithms often generate unnecessarily large ensembles, which consume extra computational resource and may degrade the generalization performance. Ensemble pruning algorithms aim to find a good subset of ensemble members to constitute a small ensemble, which saves the computational resource and performs as well as, or better than, the unpruned ensemble. This paper introduces a probabilistic ensemble pruning algorithm by choosing a set of “sparse” combination weights, most of which are zeros, to prune the ensemble. In order to obtain the set of sparse combination weights and satisfy the nonnegative constraint of the combination weights, a left-truncated, nonnegative, Gaussian prior is adopted over every combination weight. Expectation propagation (EP) algorithm is employed to approximate the posterior estimation of the weight vector. The leave-one-out (LOO) error can be obtained as a by-product in the training of EP without extra computation and is a good indication for the generalization error. Therefore, the LOO error is used together with the Bayesian evidence for model selection in this algorithm. An empirical study on several regression and classification benchmark data sets shows that our algorithm utilizes far less component learners but performs as well as, or better than, the unpruned ensemble. Our results are very competitive compared with other ensemble pruning algorithms. 相似文献
309.
310.
Sebastian Klenk Jürgen Dippon Peter Fritz Gunther Heidemann 《Information Systems Frontiers》2009,11(4):391-403
Medical data mining is currently actively pursued in computer science and statistical research but not in medical practice.
The reasons therefore lie in the difficulties of handling and statistically analyzing medical data. We have developed a system
that allows practitioners in the field to interactively analyze their data without assistance of statisticians or data mining
experts. In the course of this paper we will introduce data mining of medical data and show how this can be achieved for survival
data. We will demonstrate how to solve common problems of interactive survival analysis by presenting the Online Clinical
Data Mining (OCDM) system. Thereby the main focus is on similarity based queries, a new method to select similar cases based
on their covariables and the influence of these on their survival. 相似文献