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1.
Bayesian feature and model selection for Gaussian mixture models 总被引:1,自引:0,他引:1
Constantinopoulos C Titsias MK Likas A 《IEEE transactions on pattern analysis and machine intelligence》2006,28(6):1013-1018
We present a Bayesian method for mixture model training that simultaneously treats the feature selection and the model selection problem. The method is based on the integration of a mixture model formulation that takes into account the saliency of the features and a Bayesian approach to mixture learning that can be used to estimate the number of mixture components. The proposed learning algorithm follows the variational framework and can simultaneously optimize over the number of components, the saliency of the features, and the parameters of the mixture model. Experimental results using high-dimensional artificial and real data illustrate the effectiveness of the method. 相似文献
2.
Aristidis LikasAuthor Vitae Nikos VlassisAuthor VitaeJakob J. VerbeekAuthor Vitae 《Pattern recognition》2003,36(2):451-461
We present the global k-means algorithm which is an incremental approach to clustering that dynamically adds one cluster center at a time through a deterministic global search procedure consisting of N (with N being the size of the data set) executions of the k-means algorithm from suitable initial positions. We also propose modifications of the method to reduce the computational load without significantly affecting solution quality. The proposed clustering methods are tested on well-known data sets and they compare favorably to the k-means algorithm with random restarts. 相似文献
3.
Aristidis Stournaras Konstantinos Salonitis Panagiotis Stavropoulos George Chryssolouris 《The International Journal of Advanced Manufacturing Technology》2009,44(1-2):114-124
A theoretical model has been developed for simulating the laser grooving process. It takes into account the interaction among subsequent pulses, the required time for the melting temperature to be reached and the subsequent removal of a finite volume of material during each laser pulse. The model predicts the maximum groove depth that can be achieved for a specified set of process parameters, such as laser power, pulsing frequency, and scanning velocity. The theoretical predictions have been experimentally tested with a medium-power laser beam. 相似文献
4.
This paper introduces a new stochastic control method, Extended Linear Quadratic Gaussian control, that appears to be particularly promising for the management of complex reservoir configurations such as the River Nile system. The method is introduced by means of a short case study related to the regulation of the Equatorial Lakes in the Nile basin. If the necessary data are available, the method can be easily adapted to the entire Nile system and used to investigate a variety of management issues. 相似文献
5.
Maria Bousnaki Athina Bakopoulou Danai Papadogianni Nektaria-Marianthi Barkoula Kalliopi Alpantaki Aristidis Kritis Maria Chatzinikolaidou Petros Koidis 《Journal of materials science. Materials in medicine》2018,29(7):97
Tissue engineering (TE) may provide effective alternative treatment for challenging temporomandibular joint (TMJ) pathologies associated with disc malpositioning or degeneration and leading to severe masticatory dysfunction. Aim of this study was to evaluate the potential of chitosan/alginate (Ch/Alg) scaffolds to promote fibro/chondrogenic differentiation of dental pulp stem cells (DPSCs) and production of fibrocartilage tissue, serving as a replacement of the natural TMJ disc. Ch/Alg scaffolds were fabricated by crosslinking with CaCl2 combined or not with glutaraldehyde, resulting in two scaffold types that were physicochemically characterized, seeded with DPSCs or human nucleus pulposus cells (hNPCs) used as control and evaluated for cell attachment, viability, and proliferation. The DPSCs/scaffold constructs were incubated for up to 8 weeks and assessed for extracellular matrix production by means of histology, immunofluorescence, and thermomechanical analysis. Both Ch/Alg scaffold types with a mass ratio of 1:1 presented a gel-like structure with interconnected pores. Scaffolds supported cell adhesion and long-term viability/proliferation of DPSCs and hNPCs. DPSCs cultured into Ch/Alg scaffolds demonstrated a significant increase of gene expression of fibrocartilaginous markers (COLI, COL X, SOX9, COM, ACAN) after up to 3 weeks in culture. Dynamic thermomechanical analysis revealed that scaffolds loaded with DPSCs significantly increased storage modulus and elastic response compared to cell-free scaffolds, obtaining values similar to those of native TMJ disc. Histological data and immunochemical staining for aggrecan after 4 to 8 weeks indicated that the scaffolds support abundant fibrocartilaginous tissue formation, thus providing a promising strategy for TMJ disc TE-based replacement. 相似文献
6.
Vasileios Karavasilis Christophoros Nikou Aristidis Likas 《Image and vision computing》2011,29(5):295-305
In this paper, we demonstrate how the differential Earth Mover's Distance (EMD) may be used for visual tracking in synergy with Gaussian mixtures models (GMM). According to our model, motion between adjacent frames results in variations of the mixing proportions of the Gaussian components representing the object to be tracked. These variations are computed in closed form by minimizing the differential EMD between Gaussian mixtures, yielding a very fast algorithm with high accuracy, without recurring to the EM algorithm in each frame. Moreover, we also propose a framework to handle occlusions, where the prediction for the object's location is forwarded to an adaptive Kalman filter whose parameters are estimated on line by the motion model already observed. Experimental results show significant improvement in tracking performance in the presence of occlusion. 相似文献
7.
Sofia Pegiadou-Koemtzopoulou Ioannis Eleftheriadis Aristidis Kehayoglou 《Journal of surfactants and detergents》1998,1(1):59-64
The complex-forming interaction between two direct dyes, CI Yellow 106 and CI Blue 78, and two nonionic surfactants, namely,
polyoxyethylene nonyl phenyl ether (NP-12) and polyoxyethylene stearylamine (R-11), in aqueous solutions was studied. The
estimation was made by measuring surface tension and critical micelle concentration (CMC) changes as a function of dye concentration.
A decrease of NP-12 surface tension at low concentration and an increase of R-11 surface tension in the presence of both dyes
were observed along with a significant decrease of NP-12 CMC values. A difference in the spectrophotometric absorbance of
dye solutions in the presence of both surfactants, indicating a change in the environment of the dye chromophore, was also
visible. These results confirm the formation of hydrophobic complexes of NP-12 and hydrophilic complexes of R-11 with both
dyes. 相似文献
8.
Aristidis Stournaras George Chryssolouris 《The International Journal of Advanced Manufacturing Technology》2010,46(5-8):611-620
Laser drilling is a well established sheet metal processing method. The development of a monitoring system capable of assessing the dimensions of holes is the subject of this work. This paper investigates the applicability of an acoustic-based monitoring system for the percussion laser drilling process. Correlation between the sensor output and the hole's geometry, determined by its depth and upper diameter, is investigated and the results are presented. In general, the results indicate that a correlation exists between the acoustic signal output and the depth of the hole. 相似文献
9.
Aristidis Golfinopoulos Magdalini SoupioniNikolaos Kopsahelis Konstantina TsaousiAthanasios A. Koutinas 《Food chemistry》2012
Lactose uptake rate by kefir yeast, immobilized on tubular cellulose and gluten pellets during fermentation of lactose and whey, was monitored using 14C-labelled lactose. Results illustrated that, in all cases, lactose uptake rate was strongly correlated with fermentation rate and the fermentation’s kinetic parameters were improved by kefir yeast entrapped in tubular cellulose. As a result, twofold faster fermentations were achieved in comparison with kefir yeast immobilized on gluten. This is probably due to cluster and hydrogen bonds formation between cellulose and inhibitors, such as Ca++ and generated lactic acid, by which they leave the liquid medium. The findings, regarding the promotional effect of cellulose, seem promising for application in industrial whey fermentations. 相似文献
10.
The fuzzy min–max neural network constitutes a neural architecture that is based on hyperbox fuzzy sets and can be incrementally trained by appropriately adjusting the number of hyperboxes and their corresponding volumes. An extension to this network has been proposed recently, that is based on the notion of random hyperboxes and is suitable for reinforcement learning problems with discrete action space. In this work, we elaborate further on the random hyperbox idea and propose the stochastic fuzzy min–max neural network, where each hyperbox is associated with a stochastic learning automaton. Experimental results using the pole balancing problem indicate that the employment of this model as an action selection network in reinforcement learning schemes leads to superior learning performance compared with the traditional approach where the multilayer perceptron is employed. 相似文献