共查询到20条相似文献,搜索用时 274 毫秒
1.
Backfitting of fuzzy rules is an Iterative Rule Learning technique for obtaining the knowledge base of a fuzzy rule-based
system in regression problems. It consists in fitting one fuzzy rule to the data, and replacing the whole training set by
the residual of the approximation. The obtained rule is added to the knowledge base, and the process is repeated until the
residual is zero, or near zero. Such a design has been extended to imprecise data for which the observation error is small.
Nevertheless, when this error is moderate or high, the learning can stop early. In this kind of algorithms, the specificity
of the residual might decrease when a new rule is added. There may happen that the residual grows so wide that it covers the
value zero for all points (thus the algorithm stops), but we have not yet extracted all the information available in the dataset.
Focusing on this problem, this paper is about datasets with medium to high discrepancies between the observed and the actual
values of the variables, such as those containing missing values and coarsely discretized data. We will show that the quality
of the iterative learning degrades in this kind of problems, because it does not make full use of all the available information.
As an alternative to sequentially obtaining rules, we propose a new multiobjective Genetic Cooperative Competitive Learning
(GCCL) algorithm. In our approach, each individual in the population codifies one rule, which competes in the population in
terms of maximum coverage and fitting, while the individuals in the population cooperate to form the knowledge base.
相似文献
2.
When a flexible fuzzy rule structure such as those with antecedent in conjunctive normal form is used, the interpretability
of the obtained fuzzy model is significantly improved. However, some important problems appear related to the interaction
among this set of rules. Indeed, it is relatively easy to get inconsistencies, lack of completeness, redundancies, etc. Generally,
these properties are ignored or mildly faced. This paper, however, focuses on the design of a multiobjective genetic algorithm
that properly considers all these properties thus ensuring an effective search space exploration and generation of highly
legible and accurate fuzzy models.
相似文献
3.
Recently, multi-objective evolutionary algorithms have been applied to improve the difficult tradeoff between interpretability
and accuracy of fuzzy rule-based systems. It is known that both requirements are usually contradictory, however, these kinds
of algorithms can obtain a set of solutions with different trade-offs. This contribution analyzes different application alternatives
in order to attain the desired accuracy/interpr-etability balance by maintaining the improved accuracy that a tuning of membership
functions could give but trying to obtain more compact models. In this way, we propose the use of multi-objective evolutionary
algorithms as a tool to get almost one improved solution with respect to a classic single objective approach (a solution that
could dominate the one obtained by such algorithm in terms of the system error and number of rules). To do that, this work
presents and analyzes the application of six different multi-objective evolutionary algorithms to obtain simpler and still
accurate linguistic fuzzy models by performing rule selection and a tuning of the membership functions. The results on two
different scenarios show that the use of expert knowledge in the algorithm design process significantly improves the search
ability of these algorithms and that they are able to improve both objectives together, obtaining more accurate and at the
same time simpler models with respect to the single objective based approach.
相似文献
4.
Association Rule Mining is one of the important data mining activities and has received substantial attention in the literature.
Association rule mining is a computationally and I/ O intensive task. In this paper, we propose a solution approach for mining optimized fuzzy association rules of different orders.
We also propose an approach to define membership functions for all the continuous attributes in a database by using clustering
techniques. Although single objective genetic algorithms are used extensively, they degenerate the solution. In our approach,
extraction and optimization of fuzzy association rules are done together using multi-objective genetic algorithm by considering
the objectives such as fuzzy support, fuzzy confidence and rule length. The effectiveness of the proposed approach is tested
using computer activity dataset to analyze the performance of a multi processor system and network audit data to detect anomaly
based intrusions. Experiments show that the proposed method is efficient in many scenarios.
相似文献
5.
Ranking problems have recently become an important research topic in the joint field of machine learning and information retrieval.
This paper presented a new splitting rule that introduces a metric, i.e., an impurity measure, to construct decision trees
for ranking tasks. We provided a theoretical basis and some intuitive explanations for the splitting rule. Our approach is
also meaningful to collaborative filtering in the sense of dealing with categorical data and selecting relative features.
Some experiments were made to illustrate our ranking approach, whose results showed that our algorithm outperforms both perceptron-based
ranking and the classification tree algorithms in term of accuracy as well as speed.
相似文献
7.
Accuracy in processing time estimation of different manufacturing operations is fundamental to get more competitive prices
and higher profits in an industry. The manufacturing times of a machine depend on several input variables and, for each class
or type of product, a regression function for that machine can be defined. Time estimations are used for implementing production
plans. These plans are usually supervised and modified by an expert, so information about the dependencies of processing time
with the input variables is also very important. Taking into account both premises (accuracy and simplicity in information
extraction), a model based on TSK (Takagi–Sugeno–Kang) fuzzy rules has been used. TSK rules fulfill both requisites: the system
has a high accuracy, and the knowledge structure makes explicit the dependencies between time estimations and the input variables.
We propose a TSK fuzzy rule model in which the rules have a variable structure in the consequent, as the regression functions
can be completely distinct for different machines or, even, for different classes of inputs to the same machine. The methodology
to learn the TSK knowledge base is based on genetic programming together with a context-free grammar to restrict the valid
structures of the regression functions. The system has been tested with real data coming from five different machines of a
wood furniture industry.
相似文献
8.
We present a study of using camera-phones and visual-tags to access mobile services. Firstly, a user-experience study is described in which participants were both observed learning to interact with a prototype mobile service and interviewed
about their experiences. Secondly, a pointing-device task is presented in which quantitative data was gathered regarding the speed and accuracy with which participants aimed and clicked
on visual-tags using camera-phones. We found that participants’ attitudes to visual-tag-based applications were broadly positive,
although they had several important reservations about camera-phone technology more generally. Data from our pointing-device
task demonstrated that novice users were able to aim and click on visual-tags quickly (well under 3 s per pointing-device
trial on average) and accurately (almost all meeting our defined speed/accuracy tradeoff of 6% error-rate). Based on our findings,
design lessons for camera-phone and visual-tag applications are presented.
相似文献
9.
This paper proposes an appearance generative mixture model based on key frames for meanshift tracking. Meanshift tracking
algorithm tracks an object by maximizing the similarity between the histogram in tracking window and a static histogram acquired
at the beginning of tracking. The tracking therefore could fail if the appearance of the object varies substantially. In this
paper, we assume the key appearances of the object can be acquired before tracking and the manifold of the object appearance
can be approximated by piece-wise linear combination of these key appearances in histogram space. The generative process is
described by a Bayesian graphical model. An Online EM algorithm is proposed to estimate the model parameters from the observed
histogram in the tracking window and to update the appearance histogram. We applied this approach to track human head motion
and to infer the head pose simultaneously in videos. Experiments verify that our online histogram generative model constrained
by key appearance histograms alleviates the drifting problem often encountered in tracking with online updating, that the
enhanced meanshift algorithm is capable of tracking object of varying appearances more robustly and accurately, and that our
tracking algorithm can infer additional information such as the object poses.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
10.
In this paper, we present an Inverse Multi-Objective Robust Evolutionary (IMORE) design methodology that handles the presence
of uncertainty without making assumptions about the uncertainty structure. We model the clustering of uncertain events in
families of nested sets using a multi-level optimization search. To reduce the high computational costs of the proposed methodology
we proposed schemes for (1) adapting the step-size in estimating the uncertainty, and (2) trimming down the number of calls
to the objective function in the nested search. Both offline and online adaptation strategies are considered in conjunction
with the IMORE design algorithm. Design of Experiments (DOE) approaches further reduce the number of objective function calls
in the online adaptive IMORE algorithm. Empirical studies conducted on a series of test functions having diverse complexities
show that the proposed algorithms converge to a set of Pareto-optimal design solutions with non-dominated nominal and robustness
performances efficiently.
相似文献
11.
This paper describes the simulated car racing competition that was arranged as part of the 2007 IEEE Congress on Evolutionary
Computation. Both the game that was used as the domain for the competition, the controllers submitted as entries to the competition
and its results are presented. With this paper, we hope to provide some insight into the efficacy of various computational
intelligence methods on a well-defined game task, as well as an example of one way of running a competition. In the process,
we provide a set of reference results for those who wish to use the simplerace game to benchmark their own algorithms. The paper is co-authored by the organizers and participants of the competition.
相似文献
12.
Quantitative usability requirements are a critical but challenging, and hence an often neglected aspect of a usability engineering process. A case study is described where quantitative usability requirements played a key role in the development of a new user interface of a mobile phone. Within the practical constraints of the project, existing methods for determining usability requirements and evaluating the extent to which these are met, could not be applied as such, therefore tailored methods had to be developed. These methods and their applications are discussed. 相似文献
13.
In this paper, we propose an Interactive Object-based Image Clustering and Retrieval System (OCRS). The system incorporates
two major modules: Preprocessing and Object-based Image Retrieval. In preprocessing, an unsupervised segmentation method called
WavSeg is used to segment images into meaningful semantic regions (image objects). This is an area where a huge number of
image regions are involved. Therefore, we propose a Genetic Algorithm based algorithm to cluster these images objects and
thus reduce the search space for object-based image retrieval. In the learning and retrieval module, the Diverse Density algorithm
is adopted to analyze the user’s interest and generate the initial hypothesis which provides a prototype for future learning
and retrieval. Relevance Feedback technique is incorporated to provide progressive guidance to the learning process. In interacting
with user, we propose to use One-Class Support Vector Machine (SVM) to learn the user’s interest and refine the returned result.
Performance is evaluated on a large image database and the effectiveness of our retrieval algorithm is demonstrated through
comparative studies.
相似文献
14.
This paper addresses a soft computing-based approach to design soft sensors for industrial applications. The goal is to identify
second-order Takagi–Sugeno–Kang fuzzy models from available input/output data by means of a coevolutionary genetic algorithm
and a neuro-based technique. The proposed approach does not require any prior knowledge on the data-base and rule-base structures.
The soft sensor design is carried out in two steps. First, the input variables of the fuzzy model are pre-selected from the
secondary variables of a dynamical process by means of correlation coefficients, Kohonen maps and Lipschitz quotients. Such
selection procedure considers nonlinear relations among the input and output variables. Second, a hierarchical coevolutionary
methodology is used to identify the fuzzy model itself. Membership functions, individual rules, rule-bases and fuzzy inference
parameters are encoded into each hierarchical level and a shared fitness evaluation scheme is used to measure the performance
of individuals in such levels. The proposed methodology is evaluated by developing soft sensors to infer the product composition
in petroleum refining processes. The obtained results are compared with other benchmark approaches, and some conclusions are
presented.
相似文献
15.
One important Artificial Intelligence tool for automatic control is the use of fuzzy logic controllers, which are fuzzy rule-based
systems comprising expert knowledge in form of linguistic rules. These rules are usually constructed by an expert in the field
of interest who can link the facts with the conclusions. However, this way to work sometimes fails to obtain an optimal behaviour.
To solve this problem, within the framework of Machine Learning, some Artificial Intelligence techniques could be successfully
applied to enhance the controller behaviour.
Rule selection methods directly obtain a subset of rules from a given fuzzy rule set, removing inefficient and redundant rules
and, thereby, enhancing the controller interpretability, robustness, flexibility and control capability. Besides, different
parameter optimization techniques could be applied to improve the system accuracy by inducing a better cooperation among the
rules composing the final rule base.
This work presents a study of how two new tuning approaches can be applied to improve FLCs obtained from the expert’s experience
in non trivial problems. Additionally, we analyze the positive synergy between rule selection and tuning techniques as a way
to enhance the capability of these methods to obtain more accurate and compact FLCs. Finally, in order to show the good performance
of these approaches, we solve a real-world problem for the control of a heating, ventilating and air conditioning system.
相似文献
16.
Awareness systems have attracted significant research interest for their potential to support interpersonal relationships.
Investigations of awareness systems for the domestic environment have suggested that such systems can help individuals stay
in touch with dear friends or family and provide affective benefits to their users. Our research provides empirical evidence
to refine and substantiate such suggestions. We report our experience with designing and evaluating the ASTRA awareness system,
for connecting households and mobile family members. We introduce the concept of connectedness and its measurement through
the Affective Benefits and Costs of communication questionnaire (ABC-Q). We inform results that testify the benefits of sharing
experiences at the moment they happen without interrupting potential receivers. Finally, we document the role that lightweight,
picture-based communication can play in the range of communication media available.
相似文献
17.
The complexity of group dynamics occurring in small group interactions often hinders the performance of teams. The availability
of rich multimodal information about what is going on during the meeting makes it possible to explore the possibility of providing
support to dysfunctional teams from facilitation to training sessions addressing both the individuals and the group as a whole.
A necessary step in this direction is that of capturing and understanding group dynamics. In this paper, we discuss a particular
scenario, in which meeting participants receive multimedia feedback on their relational behaviour, as a first step towards
increasing self-awareness. We describe the background and the motivation for a coding scheme for annotating meeting recordings
partially inspired by the Bales’ Interaction Process Analysis. This coding scheme was aimed at identifying suitable observable
behavioural sequences. The study is complemented with an experimental investigation on the acceptability of such a service.
相似文献
18.
Listening to music on personal, digital devices whilst mobile is an enjoyable, everyday activity. We explore a scheme for
exploiting this practice to immerse listeners in navigation cues. Our prototype, ONTRACK, continuously adapts audio, modifying
the spatial balance and volume to lead listeners to their target destination. First we report on an initial lab-based evaluation
that demonstrated the approach’s efficacy: users were able to complete tasks within a reasonable time and their subjective
feedback was positive. Encouraged by these results we constructed a handheld prototype. Here, we discuss this implementation
and the results of field-trials. These indicate that even with a low-fidelity realisation of the concept, users can quite
effectively navigate complicated routes.
相似文献
19.
Tracking location is challenging due to the numerous constraints of practical systems including, but not limited to global
cost, device volume and weight, scalability and accuracy; these constraints are typically more severe for systems that should
be wearable and used indoors. We investigate the use of wearable solar cells to track changing light conditions (a concept
that we named LuxTrace) as a source of user displacement and activity data. We evaluate constraints of this approach and present
results from an experimental validation of displacement and activity estimation. The results indicate that a distance estimation
accuracy of 21 cm (80% quantile) can be achieved. A simple method to combine LuxTrace with complementary absolute location
estimation methods is also presented. We apply carpet-like distributed RFID tags to demonstrate online learning of new lighting
environments.
相似文献
20.
A number of mobile applications have emerged that allow users to locate one another. However, people have expressed concerns
about the privacy implications associated with this class of software, suggesting that broad adoption may only happen to the
extent that these concerns are adequately addressed. In this article, we report on our work on P eopleF inder, an application that enables cell phone and laptop users to selectively share their locations with others (e.g. friends,
family, and colleagues). The objective of our work has been to better understand people’s attitudes and behaviors towards
privacy as they interact with such an application, and to explore technologies that empower users to more effectively and
efficiently specify their privacy preferences (or “policies”). These technologies include user interfaces for specifying rules
and auditing disclosures, as well as machine learning techniques to refine user policies based on their feedback. We present
evaluations of these technologies in the context of one laboratory study and three field studies.
相似文献
|