The image features of pulmonary nodules in the cT image are inconspicuous, the shape and location is different. computer-aided detection system can increase the detection rate of lung nodules and reduce the error rate...
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ISBN:
(纸本)9781467390989
The image features of pulmonary nodules in the cT image are inconspicuous, the shape and location is different. computer-aided detection system can increase the detection rate of lung nodules and reduce the error rate, which can assist the clinicians to distinguish between benign and malignant nodules. This paper presents an improved fuzzyc-means (FcM) method based on the human visual attention model. The simulation result shows the effects of the new method used in computer-aided diagnosis.
The authors report an improved fuzzyc-meansalgorithm in comparison with the conventional one by employing a density-induced distance metric based on a novel calculation method of relative density degree. By using va...
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The authors report an improved fuzzyc-meansalgorithm in comparison with the conventional one by employing a density-induced distance metric based on a novel calculation method of relative density degree. By using various synthetic and real data sets, the clustering performance of the proposed method is systematically studied and compared with that of the conventional one. The obtained results support the conclusion that this novel method does not only inherit good characteristics of the traditional one, but also possesses improved partitions.
clustering validity function is an important research direction in clustering problems. Its idea is to specify the number of data clusters in advance so as to judge the optimal partition result on data sets. Studies h...
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clustering validity function is an important research direction in clustering problems. Its idea is to specify the number of data clusters in advance so as to judge the optimal partition result on data sets. Studies have shown that no clustering validity function can handle all types of data, and its performance is not consistently better than other indices. Therefore, a component-wise design method of the fuzzyc-means (FcM) clustering validity function based on cRITIccombination weighting is proposed by adopting components for evaluating clustering performance. The weighting method combines expert weighting and the coefficient of variation method (cRITIc), arranges and combines six validity components with weights, and generates 55 different fuzzyclustering validity functions. These clustering validity functions are then tested on six typical UcI data sets, and the function with the simplest structure and best classification performance is selected through comparison. Finally, it is compared with seven typical clustering validity functions and four common combination clustering validity evaluation methods on eight UcI data sets. The simulation results demonstrate that the proposed validity function can achieve better classification results and determine the optimal cluster number for different data sets.
The steadily growing deployment of cyber systems in smart grids (SGs) has highlighted the impacts of cyber-physical interdependencies (cPIs). Although much attention has been paid to the reliability evaluation of SGs ...
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The steadily growing deployment of cyber systems in smart grids (SGs) has highlighted the impacts of cyber-physical interdependencies (cPIs). Although much attention has been paid to the reliability evaluation of SGs considering the system uncertainties and cPIs by Monte carlo simulation (McS), the computation time is one of the essential challenges of McS-based methods. This research tries to overcome the discussed challenge by developing a new clustering-based reliability evaluation method considering the direct cPIs (DcPIs) and stochastic behaviors of renewable distributed generation units (RDGUs) and the demand side. In the proposed method, the fuzzyc-means (FcM) clusteringalgorithm has been used to reduce the number of scenarios for uncertain parameters besides the DcPIs. Determining the appropriate alternatives for the number of clusters of stochastic parameters in various cases based on cyber network topologies, DG technologies, and the penetration levels of RDGUs is another contribution of this paper. Test results of applying the proposed method to an actual test system illustrate the advantages of the proposed clustering-based method. The comparison of the proposed method with McS shows the computation time could be reduced from 21658 s to 210 s (99%), while less than 1% EENS error appears. (c) 2022 Elsevier Ltd. All rights reserved.
clustering is the process of grouping a set of physical or abstract objects into multiple similar objects. fuzzyc-means (FcM) clustering is one of the most widely used clustering methods, whose main research goal is ...
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clustering is the process of grouping a set of physical or abstract objects into multiple similar objects. fuzzyc-means (FcM) clustering is one of the most widely used clustering methods, whose main research goal is to find the optimal clustering number of data sets, which is related to whether the data can be effectively divided. The study of clustering validity function is the process of evaluating the clustering quality and determining the optimal clustering number. Based on the idea of components, six cluster performance evaluation components are proposed to define compactness, variation, similarity, overlap and separation of data sets, respectively. Then a new validity function based on FcM clusteringalgorithm is synthesized by these six components. Finally, the proposed validity function and eight typical validity functions are compared on five artificial data sets and eight UcI data sets. The simulation results show that the proposed clustering validity function can evaluate the clustering results more effectively and determine the optimal clustering number of different data sets.
fuzzyclustering is an important research field in pattern recognition, machine learning and image processing. The fuzzyc-means (FcM) clusteringalgorithm is one of the most common fuzzyclusteringalgorithms. Howeve...
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fuzzyclustering is an important research field in pattern recognition, machine learning and image processing. The fuzzyc-means (FcM) clusteringalgorithm is one of the most common fuzzyclusteringalgorithms. However, it requires a given number of clusters in advance for accurate clustering of data sets, so it is necessary to put forward a better clustering validity index to verify the clustering results. This paper presents a ratio component-wise design method of clustering validity function based on FcM clustering method. By permutation and combination of six clustering validity components representing different meanings in the form of ratio, 49 different clustering validity functions are formed. Then, these functions are verified experimentally under six kinds of UcI data sets, and a clustering validity function with the simplest structure and the best classification effect is selected by comparison. Finally, this function is compared with seven traditional clustering validity functions on eight UcI data sets. The simulation results show that the proposed validity function can better verify the classification results and determine the optimal clustering number of different data sets.
The achievement of optimal design of structures against earthquake loading is investigated by evaluating the dynamic response. First, the paper presents an efficient preliminary technique called basic modal displaceme...
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The achievement of optimal design of structures against earthquake loading is investigated by evaluating the dynamic response. First, the paper presents an efficient preliminary technique called basic modal displacements (BMD) method to evaluate the dynamic history response. Second, a fuzzy version of BMD is developed as the premier method for prediction of peak response value of structures to be used within geneticalgorithm (GA) optimization. In BMD the seismic response of a new design of structure is approximated by revising exact modal responses of the primary design of structure referred to as base model. In the other proposed method called clustered basic modal displacements (cBMD) the accuracy of BMD method to evaluate the maximum response is significantly improved by selection of different base models for created structures in the optimization process. In cBMD the base models are selected using fuzzy c-means clustering algorithm. Three structures are designed for optimal weight using GA. Results show that the proposed approach, (cBMD), is successful comparing to those found in the literature.
As a popular clusteringalgorithms, fuzzyc-means (FcM) algorithm has been used in various fields, including fault diagnosis, machine learning. To overcome the sensitivity to outliers problem and the local minimum pro...
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As a popular clusteringalgorithms, fuzzyc-means (FcM) algorithm has been used in various fields, including fault diagnosis, machine learning. To overcome the sensitivity to outliers problem and the local minimum problem of the fuzzyc-means new algorithm is proposed based on the simulated annealing (SA) algorithm and the geneticalgorithm (GA). The combined algorithm utilizes the simulated annealing algorithm due to its local search abilities. Thereby, problems associated with the geneticalgorithm, such as its tendency to prematurely select optimal values, can be overcome, and geneticalgorithmcan be applied in fuzzyclustering analysis. Moreover, the new algorithmcan solve other problems associated with the fuzzyclusteringalgorithm, which include initial clusteringcenter value sensitivity and convergence to a local minimum. Furthermore, the simulation results can be used as classification criteria for identifying several types of bearing faults. compare with the dimensionless indexes, it shows that the mutual dimensionless indexes are more suitable for clusteringalgorithms. Finally, the experimental results show that the method adopted in this paper can improve the accuracy of clustering and accurately classify the bearing faults of rotating machinery.
fuzzy c-means clustering algorithm (FcM) is a widely used clusteringalgorithm, however it has its drawbacks: the initial number of clusters needs to be determined by the manual control according to the prior knowledg...
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ISBN:
(纸本)9781467352536
fuzzy c-means clustering algorithm (FcM) is a widely used clusteringalgorithm, however it has its drawbacks: the initial number of clusters needs to be determined by the manual control according to the prior knowledge;the objective function ignores the disequilibrium problems among the sample attribute data. In view of these problems, this paper proposes a sample weighted FcM algorithm based on simulated annealing algorithm. It uses the simulated annealing algorithm which has an excellent ability of seeking global optimal solution to calculate the initial value of the number of clusters and makes certain weighting process on the clusteringcenter function and the objective function. The experiment results show that this proposed algorithm has better classification accuracy and classification accuracy rate compared with FcM algorithm and the common sample weighted FcM clusteringalgorithms. Meanwhile, this algorithm needs not to be determined the initial value of clusters manually. The improved algorithm possesses the superiority and the actual application value.
This paper devises a new detector based on singular value decomposition (SVD) and improved fuzzyc-means (FcM) clustering for automatically detecting high-frequency oscillations (HFOs) that are used for localizing sei...
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This paper devises a new detector based on singular value decomposition (SVD) and improved fuzzyc-means (FcM) clustering for automatically detecting high-frequency oscillations (HFOs) that are used for localizing seizure onset zones (SOZs) in epilepsy. First, HFO candidates (HFOcs) are obtained by the root mean square method. Next, a time-frequency analysis method is applied to eliminate spikes from HFOcs, which consists of the Stockwell transform, SVD combined with the k-medoids clusteringalgorithm, Stockwell inverse transform, and threshold method. Then, four kinds of distinctive features, i.e. mean singular values, line lengths, power ratios and spectral centroid of the rest of HFOcs, are extracted and augmented as feature vectors. These vectors are used as the input of the improved FcM clusteringalgorithm optimized by the simulated annealing algorithmcombined with the geneticalgorithm. Finally, the localization of SOZs is accomplished based on the concentrations of the detected HFOs. The superiority of the devised detector over other five existing ones is demonstrated by comparing their localization performance. (c) 2020 Elsevier B.V. All rights reserved.
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