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11.
We propose an evolutionary framework for the production of fuzzy rule bases where each rule executes an ensemble of predictors. The architecture, the rule base and the composition of the ensembles are evolved over time. To achieve this, we employ a context-free grammar within a hybrid genetic programming system using a multi-population model. As base predictors, multilayer perceptron neural networks and support vector machines are available. We apply the system to several function approximation and regression tasks and compare the results with recent research and state-of-the-art models. We conclude that the proposed architecture is competitive and has a number of very desirable features supporting automation of predictive model building and their adaptation over time. Finally, we suggest further potential research directions. 相似文献
12.
Athanasios C. Rakitzis Petros E. Maravelakis Philippe Castagliola 《Quality and Reliability Engineering International》2016,32(2):465-483
Zero‐inflated probability models are used to model count data that have an excessive number of zeros. These models are mostly useful in modeling high‐yield or health‐related processes. The zero‐inflated binomial distribution is an extension of the ordinary binomial distribution that takes into account the excess of zeros. In this paper, one‐sided cumulative sum (CUSUM)‐type control charts are proposed for monitoring increases or decreases in the parameter p of a zero‐inflated binomial process. The results of an extensive numerical study concerning the statistical design of the proposed schemes as well as their practical implementation are provided. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
13.
Athanasios C. Rakitzis Philippe Castagliola Petros E. Maravelakis 《Quality and Reliability Engineering International》2016,32(5):1837-1851
In this work, we propose and study general inflated probability distributions that can be used for modelling and monitoring unusual count data. The considered models extend the well‐known zero‐inflated Poisson distribution because they allow the excess of values, other than zero. Four simple upper‐sided control schemes are considered for the monitoring of count data based on the proposed general inflated Poisson distributions, and their performance is evaluated under various out‐of‐control situations. The usefulness of the considered models and techniques is illustrated via two real‐data examples, while practical guidelines are provided as well. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
14.
Analysis and performance evaluation of a pilot-aided interpolated channel estimator for OFDM systems
In this paper, we propose a novel pilot-aided channel estimator through interpolation for Orthogonal Frequency Division Multiplexing (OFDM) systems that replaces part of the virtual subcarriers with pilot subcarriers (pilots) reducing the interpolation error while keeping the code rate stable. A novel thorough analysis of the Mean Square Error (MSE) of the proposed estimator is given for the general case where data subcarriers are positioned before the first and after the last pilot. Simulations show the improvement of the proposed scheme in MSE and Bit Error Rate (BER) when applied to a practical OFDM wireless local area network type of system with realistic channel conditions. 相似文献
15.
Dimitris Kalles Athanasios Papagelis 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2010,14(9):973-993
When genetic algorithms are used to evolve decision trees, key tree quality parameters can be recursively computed and re-used
across generations of partially similar decision trees. Simply storing instance indices at leaves is sufficient for fitness
to be piecewise computed in a lossless fashion. We show the derivation of the (substantial) expected speedup on two bounding
case problems and trace the attractive property of lossless fitness inheritance to the divide-and-conquer nature of decision
trees. The theoretical results are supported by experimental evidence. 相似文献
16.
Athanasios Drigas Lefteris Koukianakis Yannis Papagerasimou 《Computers in human behavior》2011,27(4):1416-1423
Cognitive science is the scientific domain which studies, analyzes, simulates and infers for various aspects, functions and procedures of human mentality such as, thinking, logic, language, knowledge, memory, learning, perception and the ability to solve problems. E-psychology is in close relation with the cognitive science domain, but expands beyond it, as e-psychology is the efficient convergence of psychology and Information and Communication Technologies (ICTs). E-psychology offers a number of services such as supporting, diagnosis, assessment, therapy, counseling, intervention and tests through an effective exploitation of ICTs. This article presents a user-friendly, flexible and adaptive electronic platform, which supports both synchronous and asynchronous e-psychology activities through the use of informative and communicative tools and services, which can be adapted to support various methods of e-psychology activities. It is important to underline that e-psychology is not an alternative psychology field, but a resource to enhance the conventional psychology process. 相似文献
17.
Athanasios Vlachos Vassilis Fotopoulos Athanassios N. Skodras 《Journal of Real-Time Image Processing》2010,5(3):141-148
A comparative study of low complexity motion estimation algorithms is presented. The algorithms included in the study are
the 1-bit transform, the 2-bit transform, the constrained 1-bit transform and the multiplication free 1-bit transform which
are using different motion estimation strategies compared to standard exhaustive search algorithm-mean absolute difference
or similar combinations. These techniques provide better performance in terms of computational load compared to traditional
algorithms. Although the accuracy of motion compensation is only slightly lower comparing to the other techniques, results
in terms of objective quality (peak signal-to-noise ratio) and entropy are comparable. This fact, nominates them as suitable
candidates for inclusion in embedded devices applications where lower complexity translates to lower power consumption and
consequently improved device autonomy. 相似文献
18.
Athanasios Karagiannidis Konstantinos Lagouvardos Vassiliki Kotroni Nikos Mazarakis 《International journal of remote sensing》2016,37(20):5001-5020
An analysis of selected spatiotemporal characteristics of isolated thunderstorms in relation to cloud-to-ground (CG) lightning over part of the eastern Mediterranean is performed. The purpose of the study is twofold: to better understand and improve the basic knowledge of the physical mechanisms of the phenomenon and to offer new means of nowcasting the lightning activity in such thunderstorms. Meteosat Second Generation (MSG) Rapid Scan Service (RSS) infrared imagery which offers the option of tracking the examined storms with a time frequency of 5 minutes is one of the two utilized datasets, the other being ZEUS very low frequency (VLF) lightning detection system’s CG discharge data. It was shown that a cloud top temperature of about ?20°C is required for the onset of lightning activity. A rapid drop of the cloud-top temperature of about 11°C in 5 minutes on average is observed a few minutes before or during lightning initiation. The maximization of the activity is usually quite close to the overall minimum cloud-top temperature of the cell. A temperature increase of 3.5°C from this overall minimum can mark the end of the activity, which is also associated to the time evolution of the cell’s horizontal extent. In fact, after the cell’s horizontal area stops to increase and/or starts to gradually diminish, CG lightning activity is expected to stop. 相似文献
19.
Yufeng Wang Akihiro Nakao Athanasios V. VasilakosJianhua Ma 《Computer Communications》2011,34(3):241-249
This paper thoroughly investigates the evolutionary dynamics of soft security mechanism, namely, reciprocity-based incentive mechanism, in P2P systems based on Evolutionary Game Theory (EGT). By soft security mechanism, it means social control mechanisms to overcome peers’ selfish (rational) behaviors, and encourage cooperation in P2P systems. Specifically, there exist three strategies in P2P systems: always cooperative (ALLC), always defect (ALLD) and reciprocator (R). Instead of existing work which take it for granted that, like ALLC users, R users did not bear any information-seeking cost, we assume small reciprocation cost, and study generalized mutation-selection dynamics. Our contributions are threefold: firstly, we prove and illustrate that, in a well-mixed P2P structure, ALLD is the only strict Nash equilibrium; secondly, we infer the specific condition under which evolution dynamics exhibits rock-scissors-paper oscillation in a structured P2P population. That is, the population cycles from ALLD to R to ALLC and back to ALLD; finally, we theoretically illustrate that the intensity of selection plays an important role in the evolutionary dynamics of P2P incentive mechanism. That is, when the intensity of selection is relatively weak and reciprocation cost limits to zero, the time average can be mostly concentrated on reciprocator. In brief, considering the existence of reciprocation cost and the small mutation in P2P incentive mechanisms, unlike existing work, it is impossible to simply achieve the “absolute cooperative” in P2P incentive mechanisms. On the other hand, stochastic evolution in P2P incentive mechanism with finite population and network structure still favor reciprocation. 相似文献
20.