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71.
Francisco Louzada Mari RomanVicente G. Cancho 《Computational statistics & data analysis》2011,55(8):2516-2524
In this paper, we proposed a new two-parameter lifetime distribution with increasing failure rate, the complementary exponential geometric distribution, which is complementary to the exponential geometric model proposed by Adamidis and Loukas (1998). The new distribution arises on a latent complementary risks scenario, in which the lifetime associated with a particular risk is not observable; rather, we observe only the maximum lifetime value among all risks. The properties of the proposed distribution are discussed, including a formal proof of its probability density function and explicit algebraic formulas for its reliability and failure rate functions, moments, including the mean and variance, variation coefficient, and modal value. The parameter estimation is based on the usual maximum likelihood approach. We report the results of a misspecification simulation study performed in order to assess the extent of misspecification errors when testing the exponential geometric distribution against our complementary one in the presence of different sample size and censoring percentage. The methodology is illustrated on four real datasets; we also make a comparison between both modeling approaches. 相似文献
72.
Francisco Jes��s Mart��n-Mateos Jos�� Luis Ruiz-Reina Jos�� Antonio Alonso Mar��a Jos�� Hidalgo 《Journal of Automated Reasoning》2011,47(3):229-250
Higman??s lemma is an important result in infinitary combinatorics, which has been formalized in several theorem provers. In this paper we present a formalization and proof of Higman??s Lemma in the ACL2 theorem prover. Our formalization is based on a proof by Murthy and Russell, where the key termination argument is justified by the multiset relation induced by a well-founded relation. To our knowledge, this is the first mechanization of this proof. 相似文献
73.
Non-photorealistic (illustrative) rendering augments typical rendering models to selectively emphasize or de-emphasize specific
structures of rendered objects. Illustrative techniques may affect not only the rendering style of specific portions of an
object but also their visibility, ensuring that less important regions do not occlude more important ones. Cutaway views completely
remove occluding, unimportant structures—possibly also removing valuable context information—while existing solutions for
smooth reduction of occlusion based on importance lack precise visibility control, simplicity and generality. We introduce
a new front-to-back fragment composition equation that directly takes into account a measure of sample importance and allows smooth and precise
importance-based visibility control. We demonstrate the generality of our composition equation with several illustrative effects,
which were obtained by using a set of importance measures calculated on the fly or defined by the user. The presented composition
method is suitable for direct volume rendering as well as rendering of layered 3D models. We discuss both cases and show examples,
though focusing mainly on illustration of volumetric data. 相似文献
74.
Extensive research has been carried out in multiresolution models for many decades. The tendency in recent years has been
to harness the potential of GPUs to perform the level-of-detail extraction on graphics hardware. The aim of this work is to
present a new level-of-detail scheme based on triangles which is both simple and efficient. In this approach, the extraction
process updates vertices instead of indices, thus providing a perfect framework for adapting the algorithms to work completely
on GPU shaders. One of the key aspects of our proposal is the need for just a single rendering pass in order to obtain the
desired geometry. Moreover, coherence among the different approximations is maximized by means of a symmetric extraction algorithm,
which performs the same process when refining and coarsening the mesh. Lastly, we also introduce different uses of the scheme
to offer continuous and view-dependent resolution. 相似文献
75.
Francisco García‐Sánchez Luís Álvarez Sabucedo Rodrigo Martínez‐Béjar Luís Anido Rifón Rafael Valencia‐García Juan Miguel Gómez 《Expert Systems》2011,28(5):416-436
The increasing volume of eGovernment‐related services is demanding new approaches for service integration and interoperability in this domain. Semantic web (SW) technologies and applications can leverage the potential of eGovernment service integration and discovery, thus tackling the problems of semantic heterogeneity characterizing eGovernment information sources and the different levels of interoperability. eGovernment services will therefore be semantically described in the foreseeable future. In an environment with semantically annotated services, software agents are essential as the entities responsible for exploiting the semantic content in order to automate some tasks, and so enhance the user's experience. In this paper, we present a framework that provides a seamless integration of semantic web services and intelligent agents technologies by making use of ontologies to facilitate their interoperation. The proposed framework can assist in the development of powerful and flexible distributed systems in complex, dynamic, heterogeneous, unpredictable and open environments. Our approach is backed up by a proof‐of‐concept implementation, where the breakthrough of integrating disparate eGovernment services has been tested. 相似文献
76.
Mauthe Andreas Garcia Francisco Hutchison David Yeadon Nicholas 《Multimedia Tools and Applications》2001,13(3):285-306
Multimedia group applications often operate in an environment where the various participants are located on systems and communication links with different capabilities. Mechanisms are required that ensure full-quality media for high-performance workstations but lower-quality media for playout at low-end systems. QoS filters have been proposed as a way to adapt QoS to the user specified level by changing the structure of a media stream in a well defined way. Resource reservation and QoS filter instantiation should be closely integrated since both represent one particular aspect of the provision of individualistic QoS for heterogeneous users in multipeer communications. The Internet reservation protocol RSVP is receiver oriented and allows each receiver to specify its resource requirements. However, no actual mechanisms are defined that adapt the data stream to the receiver specified QoS requirements.In this paper we present an enhanced version of RSVP (called RSVP++) that integrates resource reservation and QoS filter control. In order to achieve this integration we extend the RSVP functional model and define a new QoS service class. RSVP++ can coexist with common RSVP systems, thus, openness and interoperability of the system are ensured. 相似文献
77.
Juan Francisco Gómez-Lopera José Martínez-Aroza Aureliano M. Robles-Pérez Ramón Román-Roldán 《Journal of Mathematical Imaging and Vision》2000,13(1):35-56
This work constitutes a theoretical study of the edge-detection method by means of the Jensen-Shannon divergence, as proposed by the authors. The overall aim is to establish formally the suitability of the procedure of edge detection in digital images, as a step prior to segmentation. In specific, an analysis is made not only of the properties of the divergence used, but also of the method's sensitivity to the spatial variation, as well as the detection-error risk associated with the operating conditions due to the randomness of the spatial configuration of the pixels. Although the paper deals with the procedure based on the Jensen-Shannon divergence, some problems are also related to other methods based on local detection with a sliding window, and part of the study is focused to noisy and textured images. 相似文献
78.
Formal translations constitute a suitable framework for dealing with many problems in pattern recognition and computational linguistics. The application of formal transducers to these areas requires a stochastic extension for dealing with noisy, distorted patterns with high variability. In this paper, some estimation criteria are proposed and developed for the parameter estimation of regular syntax-directed translation schemata. These criteria are: maximum likelihood estimation, minimum conditional entropy estimation and conditional maximum likelihood estimation. The last two criteria were proposed in order to deal with situations when training data is sparse. These criteria take into account the possibility of ambiguity in the translations: i.e., there can be different output strings for a single input string. In this case, the final goal of the stochastic framework is to find the highest probability translation of a given input string. These criteria were tested on a translation task which has a high degree of ambiguity. 相似文献
79.
Fernández-Miyakawa ME Dorr R Fernández LE Uzal FA Ibarra C 《Computer methods and programs in biomedicine》2007,85(2):95-100
This paper describes the development of a simple system for measurement of net water movement through biological membrane barriers. The system is based on the detection of a water meniscus inside a polyethylene tube, which reflects the water movement inside one hemichamber of a modified Ussing chamber containing a membrane barrier. The detection device consists of a commercial computer-controlled flat bed scanner and specifically developed software. This system allows one to perform a relatively high number of individual experiments per physical unit. It is a flexible and affordable device, which allows comparatively more information per unit to be obtained than previously described methods. 相似文献
80.
Detecting and tracking human faces in video sequences is useful in a number of applications such as gesture recognition and
human-machine interaction. In this paper, we show that online appearance models (holistic approaches) can be used for simultaneously
tracking the head, the lips, the eyebrows, and the eyelids in monocular video sequences. Unlike previous approaches to eyelid
tracking, we show that the online appearance models can be used for this purpose. Neither color information nor intensity
edges are used by our proposed approach. More precisely, we show how the classical appearance-based trackers can be upgraded
in order to deal with fast eyelid movements. The proposed eyelid tracking is made robust by avoiding eye feature extraction.
Experiments on real videos show the usefulness of the proposed tracking schemes as well as their enhancement to our previous
approach.
相似文献
Javier OrozcoEmail: |