Multidimensional Data Clustering Research Articles

Phenotyping left ventricular systolic dysfunction in asymptomatic individuals for improved risk stratification.

Left ventricular systolic dysfunction (LSVD) is a heterogeneous condition with several factors influencing prognosis. Better phenotyping of asymptomatic individuals can inform preventative strategies. This study aims to explore the clinical phenotypes of LVSD in initially asymptomatic subjects and their association with clinical outcomes and cardiovascular abnormalities through multi-dimensional data clustering. Clustering analysis was performed on 60 clinically available variables from 1563 UK Biobank participants without pre-existing heart failure (HF) and with left ventricular ejection fraction (LVEF) < 50% on cardiovascular magnetic resonance (CMR) assessment. Risks of developing HF, other cardiovascular events, death, and a composite of major adverse cardiovascular events (MACE) associated with clusters were investigated. Cardiovascular imaging characteristics, not included in the clustering analysis, were also evaluated. Three distinct clusters were identified, differing considerably in lifestyle habits, cardiovascular risk factors, electrocardiographic parameters, and cardiometabolic profiles. A stepwise increase in risk profile was observed from Cluster 1 to Cluster 3, independent of traditional risk factors and LVEF. Compared with Cluster 1, the lowest risk subset, the risk of MACE ranged from 1.42 [95% confidence interval (CI): 1.03-1.96; P < 0.05] for Cluster 2 to 1.72 (95% CI: 1.36-2.35; P < 0.001) for Cluster 3. Cluster 3, the highest risk profile, had features of adverse cardiovascular imaging with the greatest LV re-modelling, myocardial dysfunction, and decrease in arterial compliance. Clustering of clinical variables identified three distinct risk profiles and clinical trajectories of LVSD amongst initially asymptomatic subjects. Improved characterization may facilitate tailored interventions based on the LVSD sub-type and improve clinical outcomes.

Multidimensional heterogeneous data clustering algorithm for power transmission and transformation equipment

Considering that the operation of power transmission and transformation equipment is not timely discovered due to the untimely data integration, a multi-dimensional heterogeneous data clustering algorithm for power transmission and transformation equipment based on multimodal deep learning is proposed. The multi-modal deep learning method is used to mine relevant data and measure the similarity between the data, which can improve the accuracy of subsequent multi-bit heterogeneous data clustering of power transmission and transformation equipment. Set up a clustering center and process data clustering to complete multi-dimensional heterogeneous data clustering of power transmission and transformation equipment. The experimental results show that the method has high clustering accuracy in the clustering of voltage deviation overrun times, voltage harmonic total distortion rate overrun times, and voltage flicker overrun times.

K-Anonymity Privacy Protection Algorithm for Multi-Dimensional Data against Skewness and Similarity Attacks.

Currently, a significant focus has been established on the privacy protection of multi-dimensional data publishing in various application scenarios, such as scientific research and policy-making. The K-anonymity mechanism based on clustering is the main method of shared-data desensitization, but it will cause problems of inconsistent clustering results and low clustering accuracy. It also cannot defend against several common attacks, such as skewness and similarity attacks at the same time. To defend against these attacks, we propose a K-anonymity privacy protection algorithm for multi-dimensional data against skewness and similarity attacks (KAPP) combined with t-closeness. Firstly, we propose a multi-dimensional sensitive data clustering algorithm based on improved African vultures optimization. More specifically, we improve the initialization, fitness calculation, and solution update strategy of the clustering center. The improved African vultures optimization can provide the optimal solution with various dimensions and achieve highly accurate clustering of the multi-dimensional dataset based on multiple sensitive attributes. It ensures that multi-dimensional data of different clusters are different in sensitive data. After the dataset anonymization, similar sensitive data of the same equivalence class will become less, and it eventually does not satisfy the premise of being theft by skewness and similarity attacks. We also propose an equivalence class partition method based on the sensitive data distribution difference value measurement and t-closeness. Namely, we calculate the sensitive data distribution's difference value of each equivalence class and then combine the equivalence classes with larger difference values. Each equivalence class satisfies t-closeness. This method can ensure that multi-dimensional data of the same equivalence class are different in multiple sensitive attributes, and thus can effectively defend against skewness and similarity attacks. Moreover, we generalize sensitive attributes with significant weight and all quasi-identifier attributes to achieve anonymous protection of the dataset. The experimental results show that KAPP improves clustering accuracy, diversity, and anonymity compared to other similar methods under skewness and similarity attacks.

TreeKDE: clustering multivariate data based on decision tree and using one-dimensional kernel density estimation

In this paper, we present an algorithm for clustering multidimensional data, which we named TreeKDE. It is based on a tree structure decision associated with the optimization of the one-dimensional kernel density estimator function constructed from the orthogonal projections of the data on the coordinate axes. Among the main features of the proposed algorithm, we highlight the automatic determination of the number of clusters and their insertion in a rectangular region. Comparative numerical experiments are presented to illustrate the performance of the proposed algorithm and the results indicate that the TreeKDE is efficient and competitive when compared to other algorithms from the literature. Features such as simplicity and efficiency make the proposed algorithm an attractive and promising research field, which can be used as a basis for its improvement, and also for the development of new clustering algorithms based on the association between decision tree and kernel density estimator.

Identification of urban-rural integration types in China – an unsupervised machine learning approach

PurposeDevelopment of urban-rural integration is essential to fulfill sustainable development goals worldwide, and comprehension about urban-rural integration types has been highlighted as increasingly relevant for an efficient policy design. This paper aims to utilize an unsupervised machine learning approach to identify urban-rural integration typologies based on multidimensional metrics regarding economic, population and social integration in China.Design/methodology/approachThe study introduces partitioning around medoids (PAM) for the identification of urban-rural integration typologies. PAM is a powerful tool for clustering multidimensional data. It identifies clusters by the representative objects called medoids and can be used with arbitrary distance, which help make clustering results more stable and less susceptible to outliers.FindingsThe study identifies four clusters: high-level urban-rural integration, urban-rural integration in transition, low-level urban-rural integration and early urban-rural integration in backward stage, showing different characteristics. Based on the clustering results, the study finds continuous improvement in urban-rural integration development in China which is reflected by the changes in the predominate type. However, the development still presents significant regional disparities which is characterized by leading in the east regions and lagging in the western and central regions. Besides, achievement in urban-rural integration varies significantly across provinces.Practical implicationsThe machine learning techniques could identify urban-rural integration typologies in a multidimensional and objective way, and help formulate and implement targeted strategies and regionally adapted policies to boost urban-rural integration.Originality/valueThis is the first paper to use an unsupervised machine learning approach with PAM for the identification of urban-rural integration typologies from a multidimensional perspective. The authors confirm the advantages of this machine learning techniques in identifying urban-rural integration types, compared to a single indicator.

Robust mean shift filter for mixed Gaussian and impulsive noise reduction in color digital images

Noise reduction is one of the most important topics of digital image processing and despite the fact that it has been studied for a long time it remains the subject of active research. In the following work, we present an extension of the Mean Shift technique, which is efficiently reducing the Gaussian noise, so that it is able to cope with the impulsive disturbances. Furthermore, the elaborated technique can be applied to enhance the images corrupted by a mixture of strong Gaussian and impulsive noise, severely decreasing the quality of color digital images. By means of our approach, which is based on a novel similarity measure between a pixel and a patch located in the center of the processing block, even heavily disturbed images can be effectively restored, which enables the success of further stages of the image processing pipeline. We evaluate the efficiency of the proposed method using a publicly available database of test color images and compare the restored images applying a set of standard quality metrics with the results delivered by state-of-the-art denoising methods. Additionally, we compare our method with the Medoid and Quick Shift techniques, accelerating the original Mean Shift algorithm, in terms of objective quality criteria and computational complexity. The results of the performed experiments indicate that the proposed technique is superior to the widely used denoising techniques and can be used as a robust extension of the Mean Shift procedure. In the paper, a particular emphasis is placed on the ability of the presented algorithm to preserve and enhance image edges. The performed experiments evaluated with the use of the Pratt’s index, quantitatively confirm the superiority of the proposed design over the Mean Shift and standard denoising methods. The preservation of edges and even their sharpening is a very important feature of our algorithm whereas the final goal is segmentation, playing a crucial role in various computer vision tasks. The proposed algorithm is intended for the mixed noise reduction in color images, but it can be also applied in multispectral imaging and clustering of multidimensional data. To enable the comparison of our method with the standard denoising techniques and to help applying it in other image processing fields, we made its code freely available.

Artificial intelligence methods in the study of the economic potential of Russian regions in conditions of grand challenges

Subject. The article investigates methodological approaches to the analysis of economic potential of regions, considering the achievement of the national goal of sustainable development of the Russian Federation in conditions of grand challenges. Objectives. The aim is to study the dynamics of economic activity in Russian regions, using artificial intelligence methods, to analyze the innovative development of the Russian economy in the face of grand challenges. Methods. The study rests on the analysis of development indicators of the regional economy of Russia. We propose a cluster analysis of the regional economy development, free from model constraints, based on neural network modeling, which enables to assess the dynamics of development and ranking of Russian regions, according to the totality of considered indicators. We apply Kohonen self-organizing maps as a promising means of clustering and visual embodiment of multidimensional statistical data. Results. The neural network modeling enabled to segregate 85 regions of the Russian Federation into four compact groups. We estimated the significance of each indicator in the formation of clusters, revealed a strong difference in the number of regions in the clusters. In the period under review, some regions were part of the same corresponding cluster. The paper presents the dynamics of average values of the studied indicators in clusters for 2018–2020. Conclusions. We demonstrate a disproportion of economic development of Russian regions. It requires an individual approach to regional economy’s strategy development, corresponding KPIs, and measures to stimulate economic activity in the field of innovation, investment, and introduction of research results in the regions of the Russian Federation.

Human-supervised clustering of multidimensional data using crowdsourcing.

Clustering is a central task in many data analysis applications. However, there is no universally accepted metric to decide the occurrence of clusters. Ultimately, we have to resort to a consensus between experts. The problem is amplified with high-dimensional datasets where classical distances become uninformative and the ability of humans to fully apprehend the distribution of the data is challenged. In this paper, we design a mobile human-computing game as a tool to query human perception for the multidimensional data clustering problem. We propose two clustering algorithms that partially or entirely rely on aggregated human answers and report the results of two experiments conducted on synthetic and real-world datasets. We show that our methods perform on par or better than the most popular automated clustering algorithms. Our results suggest that hybrid systems leveraging annotations of partial datasets collected through crowdsourcing platforms can be an efficient strategy to capture the collective wisdom for solving abstract computational problems.

Multivariate Wind Turbine Power Curve Model Based on Data Clustering and Polynomial LASSO Regression

Wind turbine performance monitoring is a complex task because of the non-stationary operation conditions and because the power has a multivariate dependence on the ambient conditions and working parameters. This motivates the research about the use of SCADA data for constructing reliable models applicable in wind turbine performance monitoring. The present work is devoted to multivariate wind turbine power curves, which can be conceived of as multiple input, single output models. The output is the power of the target wind turbine, and the input variables are the wind speed and additional covariates, which in this work are the blade pitch and rotor speed. The objective of this study is to contribute to the formulation of multivariate wind turbine power curve models, which conjugate precision and simplicity and are therefore appropriate for industrial applications. The non-linearity of the relation between the input variables and the output was taken into account through the simplification of a polynomial LASSO regression: the advantages of this are that the input variables selection is performed automatically. The k-means algorithm was employed for automatic multi-dimensional data clustering, and a separate sub-model was formulated for each cluster, whose total number was selected by analyzing the silhouette score. The proposed method was tested on the SCADA data of an industrial Vestas V52 wind turbine. It resulted that the most appropriate number of clusters was three, which fairly resembles the main features of the wind turbine control. As expected, the importance of the different input variables varied with the cluster. The achieved model validation error metrics are the following: the mean absolute percentage error was in the order of 7.2%, and the average difference of mean percentage errors on random subsets of the target data set was of the order of 0.001%. This indicates that the proposed model, despite its simplicity, can be reliably employed for wind turbine power monitoring and for evaluating accumulated performance changes due to aging and/or optimization.

The effects of multidimensional data clustering on the accuracy of virtual in-situ calibration in the photovoltaic/Thermal heat pump system

Sensor errors have a significant negative impact on the control, diagnosis, and optimisation of building energy systems. The virtual in-situ calibration (VIC) method based on Bayesian inference and the Monte Carlo Markov chain can diagnose and calibrate sensor faults without installing new sensors. In previous studies, the historical data incorporated into the VIC method were typically measured under a certain steady-state operating condition without considering the multiple operating conditions of the system. In an actual photovoltaic/thermal heat pump (PV/T-HP) system, the overall system consists of a variety of operating conditions owing to changes in solar radiation, wind speed, or temperature. A sensor under different operating conditions produces different systematic and random errors, which affect the calibration. To solve this problem, the Gaussian mixture model (GMM) based on probability is applied to pre-process the data of various operating conditions, so that each steady-state operating condition has the same Gaussian distribution to ensure the consistency of errors. To verify the validity of the GMM clustering and the accuracy of the VIC method, four operating conditions are set according to the actual working state. The results indicate that the GMM can be used to cluster these mixed working conditions well, which guarantees the selection of the following steady-state measurements. In addition, the steady-state measurements of different operating conditions are incorporated into the VIC method, the systematic and random errors are reduced by 86% and 42%, respectively. Meanwhile, the systematic error accuracy for large faults increases by 12% (from 86% to 98%) compared with that for small faults after calibration, and the random error accuracy for large faults increases by 38% (from 42% to 80%) compared with that for small faults. In general, the VIC method based on GMM broadens the scope of sensor fault repair and lays a foundation for future applications in actual systems.

Studying the innovative development of regional economy as an imperative of sustainable socio-economic growth in Russia, using neural network modeling

Subject. The article deals with the innovative potential of Russian regions in light of the national goal of the Russian Federation development, reflecting decent and productive work. Objectives. The purpose is to study the innovation activity in Russian regions, using neural networks, to ensure breakthrough innovative development of the Russian economy. Methods. We employ a cluster analysis on the basis of neural network modeling, using information technologies. For the research, we selected neural networks (Kohonen self-organizing maps), which are focused on unsupervised learning and are a promising tool for clustering and visualization of multidimensional statistical data. Results. The result of neural network modeling was the ranking of 85 regions of the Russian Federation into 5 compact groups (clusters) regardless of their affiliation to federal districts of the Russian Federation. The study shows that there is a strong differentiation of the number of regions in these clusters. We obtained average values of indicators in the clusters and compared them with all-Russian indicators. Conclusions. Breakthrough in the socio-economic growth of the Russian Federation is associated with a set of measures that involve stimulating innovation activities in regions, which are characterized by different level of innovation development. Such measures will increase the interest of the real sector of the economy in using scientific development, advanced production technologies, higher-productivity employment opportunities, and, as a result, will encourage socio-economic growth and people's quality of life.

K-Means Clustering-Aided Non-Coherent Detection for Molecular Communications

In this paper, we consider non-coherent detection schemes for molecular communication systems in the presence of inter-symbol-interference. In particular, we study non-coherent detectors based on memory-bits-based thresholds in order to achieve low bit-error-ratio (BER) transmission. The main challenge of realizing detectors based on memory-bits-based thresholds is to obtain the channel state information based only on the received signals. We tackle this issue by reformulating the thresholds through intermediate variables, which can be obtained by clustering multi-dimensional data from the received signals, and by using the K-means clustering algorithm. In addition to estimating the thresholds, we show that the transmitted bits can be retrieved from the clustered data. To reduce clustering errors, we propose iterative clustering methods from one-dimensional to multi-dimensional data, which are shown to reduce the BER. Simulation results are presented to verify the effectiveness of the proposed methods.

Advanced consistency management of highly-distributed transactional database in a hybrid cloud environment using novel R-TBC/RTA approach

This paper examines possibilities for improving the existing strategies of consistency management for highly-distributed transactional database in a hybrid cloud environment. With a detailed analysis of the existing consistency models for distributed database and standard strategies including Classic, Quorum and Tree Based Consistency (TBC), it is concluded that an improved advanced model of so-called visible adaptive consistency needs to be applied in a highly-distributed cloud environment, as necessary and sufficient degree of synchronization of all replicas. Along with the proposed model, research and development of an advanced novel strategy for consistency management Rose TBC (R-TBC) approach has been conducted, by improving standard TBC approach. Regarding implementation, a specific agglomerative Rose Tree Algorithm (RTA) has been developed, based on Bayesian hierarchical clustering and Graph Partitioning Algorithm - Multidimensional Data Clustering (GPA-MDC) intelligent partitioning of transactional Cloud Database Management System (CDBMS). The final result is constructed R-TBC model that changes in accordance with dynamic changes of entire heterogeneous CDBMS environment.

Neural network modeling of tourism development as a factor of sustainable economic growth in Russian regions

The features of the development of the tourism sector in the regions of the Russian Federation, which have an impact on the socio-economic development of the country, have been investigated. Analysis of the current state of the tourism sector, classified as the main types of economic activity, is relevant and important for increasing the competitiveness of the regions of the Russian Federation and ensuring the economic security of the state. The study is aimed to model and analyze tourist cluster formations in Russia. The study of tourist activity in the regions of Russia based on the indicators of the database of the Federal State Statistics Service was carried out using a new promising approach - cluster analysis using the scientific and methodological apparatus of artificial neural networks. The distribution of Russian regions into five tourist clusters has been obtained as a result of clustering multidimensional data using neural networks - self-organizing Kohonen maps, which are focused on self-study, and modern information technologies. In neural network modeling, the six-dimensional space of tourism development indicators was mapped, taking into account the topology, into a two-dimensional space, which made it possible to visualize the results of grouping regions by tourist clusters. The features of the development of the tourism sector in the regions of the Russian Federation have been revealed by the totality of the considered indicators The obtained results state that there is a strong variation in the number of regions by tourist clusters and the ametric nature of the development of tourist activity in the regions of Russia. The results of the study are of practical significance for the strategic planning of the tourism sector development, which ensures the development of domestic and inbound tourism. Analysis of the functioning of the tourism sector in the regions of the Russian Federation allows concluding the necessity to take a set of measures to stimulate effective investment activity in a number of tourism clusters, harmonizing the strategies of the state and business, which will contribute to the renewal and competitiveness of this type of economic activity.

Soft clustering by convex electoral model

In this paper, we suggest a new technique for soft clustering of multidimensional data. It is based on a new convex voting model, where each voter chooses a party with certain probability depending on the divergence between his/her preferences and the position of the party. The parties can react on the results of polls by changing their positions. We prove that under some natural assumptions this system has a unique fixed point, providing a unique solution for soft clustering. The solution of our model can be found either by imitation of the sequential elections, or by direct minimization of a convex potential function. In both cases, the methods converge linearly to the solution. We provide our methods with worst-case complexity bounds. To the best of our knowledge, these are the first polynomial-time complexity results in this field.

Learning Adaptive Neighborhood Graph on Grassmann Manifolds for Video/Image-Set Subspace Clustering

The objective of self-expression based spectral clustering is to learn an affinity matrix which accurately reflects the similarity among data, and the Laplacian constraint is usually exploited to make the affinity matrix preserve the global structure of raw data. However, there exist two drawbacks: firstly, these methods are mostly designed for vectorial data in Euclidean spaces, which are not suitable for multidimensional data with nonlinear manifold structure, e.g., videos and image-sets. Secondly, the clustering performance heavily relies on the quality of a pre-learned Laplacian matrix in which the global structure may be mis-interpreted without considering manifold structures. In this paper, we firstly provide a unified framework about self-expression learning on Grassmann manifolds, which implements the clustering tasks for multidimensional data under subspace views. Then, to assign optimal neighbors to each data depending on the local distance, we adaptively learn the neighborhood relationship from the obtained self-expression coefficient matrix, referred to Learning Adaptive Neighborhood Graph on Grassmann manifolds (GMAN). In the optimization process, the neighborhood relationship can be adaptively learned and updated with the coefficient matrix. The experimental results on five public datasets show that the proposed method is obviously better than many related clustering methods based on Grassmann manifolds, proving the effectiveness of GMAN in multidimensional data clustering.

A new local density and relative distance based spectrum clustering

A novel local density and relative distance-based spectrum clustering (LDRDSC) algorithm is proposed for multidimensional data clustering. The density spectra consider both redefined local densities and relative distances. The spectral peaks are defined as cluster centers since these peaks correspond to the local density maximums. Different clusters correspond to different spectra. The clustering by fast search and find of density peaks (CFSFDP) algorithm and several benchmark data sets are employed to validate our proposed LDRDSC algorithm. Once the density spectrum is generated, the rest points can be automatically clustered by our LDRDSC algorithm, which is different from CFSFDP. CFSFDP needs to categorize data points according to the cluster centers. Furthermore, our LDRDSC algorithm is compared with other five typical clustering algorithms (DBSCAN, FCM, AP, Mean Shift and k-means) in order to validate the effectiveness of the proposed algorithm. Computational results demonstrate that our algorithm can obtain a better clustering result than the above mentioned algorithms, especially in identifying noises or isolates.

FEATURE VECTOR GENERATION FOR THE FACIAL EXPRESSION RECOGNITION USING NEO-FUZZY SYSTEM

Context. The article is devoted to the problem of a training data set forming for the automatic human emotions recognition system on the basis of a multidimensional extended neo-fuzzy neuron. The aspects of choice the attributes vector’s dimension and composition, their influence on the system learning rate are considered. The object of research is the method of multidimensional data clustering. The subject of research is two-dimensional images geometric features systematization. Objective. The main goal of the work is to develop an approach to person’s face expression description using geometric features fixed set that can be obtained by video sequence frames processing. Method. To study the facial expressions recognition system it is proposed to form a feature vector consisting of characteristic points coordinates. There were selected points that relate to the location and shape of the eyelids, eyebrows, eye pupils, lips contours, nose wings, nasolabial folds. Such points can be easily found during the automatic image processing using known contour detectors. Also, the possibility of using for the human facial expression description not the coordinates of characteristic points, but the distances between them, was investigated. From these distances a different feature vector was created, the properties of which were compared with the points coordinates vector. Results. The developed recognition system on the basis of a multidimensional extended neo-fuzzy neuron have been implemented in software and investigated for solving the problem of facial expression classification. A comparison between the attribute vectors that are different in composition and dimension is made. The structure for the feature vector, which provides high system learning rate, and does not require the additional structural elements was chosen. Conclusions. The experimental study fully confirms the effectiveness of the developed approach for the human facial expressions recognition using a multidimensional extended neo-fuzzy neuron.

PPK-Means: Achieving Privacy-Preserving Clustering Over Encrypted Multi-Dimensional Cloud Data

Clustering is a fundamental and critical data mining branch that has been widely used in practical applications such as user purchase model analysis, image color segmentation, outlier detection, and so on. With the increasing popularity of cloud computing, more and more encrypted data are converging to cloud computing platforms for enjoying the revolutionary advantages of the cloud computing paradigm, as well as mitigating the deeply concerned data privacy issues. However, traditional data encryption makes existing clustering schemes no more effective, which greatly obstructs effective data utilization and frustrates the wide adoption of cloud computing. In this paper, we focus on solving the clustering problem over encrypted cloud data. In particular, we propose a privacy-preserving k-means clustering technology over encrypted multi-dimensional cloud data by leveraging the scalar-product-preserving encryption primitive, called PPK-means. The proposed technique is able to achieve efficient multi-dimensional data clustering as well to preserve the confidentiality of the outsourced cloud data. To the best of our knowledge, our work is the first to explore the privacy-preserving multi-dimensional data clustering in the cloud computing environment. Extensive experiments in simulation data-sets and real-life data-sets demonstrate that our proposed PPK-means is secure, efficient, and practical.

Feature proposal model on multidimensional data clustering and its application

Unsupervised learning based on clustering is an important field of artificial intelligence. In recent years, most studies focused on improving the performance of clustering algorithms by balancing the number of samples in each class or removing the noise features by iterative optimization. However, these methods are not suitable for some practical classification tasks, such as image segmentation and salient region proposals. Due to pixels or superpixels belonging to different objects in different images are not balanced, and it is difficult to use a limited number of features to describe classifying different objects, these algorithms cannot achieve high-performance classification in these tasks. In this paper, we put forward a feature proposal (FeatPro) model that can dynamically select useful features for different tasks. Furthermore, we design a feature non-maximum suppression (FNMS) algorithm, in order to achieve high performance classification by using as few features as possible. Experiments show that our method obtains competitive results on standard classification datasets and in the application of salient object segmentation.