Whole brain tractography data contain a large number of streamlines that require algorithms such as clustering to group the data into smaller sets for visualization and analysis. We present a deep-learning clustering ...
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ISBN:
(纸本)9798331528669;9798331528652
Whole brain tractography data contain a large number of streamlines that require algorithms such as clustering to group the data into smaller sets for visualization and analysis. We present a deep-learning clustering algorithm based on the latent space of a variational autoencoder trained on the direct and flipped versions of the streamlines from 10 tractograms (17,294,232 streamlines in total). The model takes advantage of the low-dimensional representation of the data in latent space to apply an HDBSCAN clustering algorithm to perform automatic and fast clustering of the tractography datasets. The proposed method was evaluated in terms of segmentation quality using the Davies-Bouldin index (DB) and execution time against two other state-of-the-art methods, QuickBundles (QB) and FFClust. The results show that the proposed method has the best performance in terms of the DB index, closely followed by QB, and is the second fastest method, only slightly surpassed by FFClust. In addition, the proposed method allows for obtaining meaningful large clusters because it uses metrics based on the density of the groups instead of a distance threshold as the other methods.
Outlier detection aims to identify data anomalies exhibiting significant deviations from normal patterns. However, existing outlier detection methods based on k-nearest neighbors often struggle with challenges such as...
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Outlier detection aims to identify data anomalies exhibiting significant deviations from normal patterns. However, existing outlier detection methods based on k-nearest neighbors often struggle with challenges such as increasing outlier counts and cluster formation issues. Additionally, selecting appropriate nearest-neighbor parameters presents a significant challenge, as researchers commonly evaluate detection accuracy across various k values. To enhance the accuracy and robustness of outlier detection, in this paper we propose an outlier detection method based on the improved DPC algorithm and centrifugal factor. Initially, we leverage k-nearest neighbors, kreciprocal nearest neighbors, and Gaussian kernel function to determine the local density of samples, particularly addressing scenarios where the DPC algorithm struggles to identify cluster centers in sparse clusters. Subsequently, to reduce the DPC algorithm's computational complexity, we screen the samples based on mutual nearest neighbor counts and select cluster centers accordingly. Non-central points are then distributed using k-nearest neighbors, k-reciprocal nearest neighbors, and reverse k-nearest neighbors. The centrifugal factor, whose magnitude reflects the outlier degree of samples, is then computed by calculating the ratio of the local kernel density at the cluster center to that of samples. Finally, we propose a method for choosing the nearest neighbor parameter, k. To comprehensively evaluate the outlier detection performance of the proposed algorithm, we conduct experiments on 12 complex synthetic datasets and 25 public real-world datasets, comparing the results with 12 state-of-the-art outlier detection methods.
In this paper, we propose a novel posterior belief clustering (PBC) algorithm to solve the tradeoff between target tracking performance and sensors energy consumption in wireless sensor networks. We model the target t...
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In this paper, we propose a novel posterior belief clustering (PBC) algorithm to solve the tradeoff between target tracking performance and sensors energy consumption in wireless sensor networks. We model the target tracking under dynamic uncertain environment using partially observable Markov decision processes (POMDPs), and transform the optimization of the tradeoff between tracking performance and energy consumption into yielding the optimal value function of POMDPs. We analyze the error of a class of continuous posterior beliefs by Kullback-Leibler (KL) divergence, and cluster these posterior beliefs into one based on the error of KL divergence. So, we calculate the posterior reward value only once for each cluster to eliminate repeated computation. The numerical results show that the proposed algorithm has its effectiveness in optimizing the tradeoff between tracking performance and energy consumption.
Safety risk assessment is essential for evaluating the health status and averting sudden battery failures in electric vehicles. This study introduces a novel safety risk assessment approach for battery systems, addres...
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Safety risk assessment is essential for evaluating the health status and averting sudden battery failures in electric vehicles. This study introduces a novel safety risk assessment approach for battery systems, addressing both cell and pack levels with three key indexes. The core of the assessment lies in representing the relative deviation of cell voltages through scatter diagrams across various stages of service life. Specifically, the study quantifies voltage deviations and deviation angles within different state of charge intervals to gauge safety risks at the cell level. Leveraging clustering algorithms aids in identifying outlier values. Furthermore, the dispersion of scatter points is utilized to assess safety risks at the pack level. Validation of this proposed model is conducted through cycling tests on battery modules with a deformed cell, demonstrating its efficacy in capturing inconsistent features of mechanical deformation abuse across the three indexes, thereby triggering alarms during operation. Moreover, the method is applied to assess the safety risks of five hazardous and accident-prone vehicles, enabling comprehensive evaluation of potential faulty cells and safety risks at the pack level. This proposed approach offers a fresh perspective on the comprehensive safety risk assessment of battery systems.
Trains playa vital role in the life of residents. Fault detection of trains is essential to ensuring their safe operation. Aiming at the problems of many parameters, slow detection speed, and low detection accuracy of...
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Trains playa vital role in the life of residents. Fault detection of trains is essential to ensuring their safe operation. Aiming at the problems of many parameters, slow detection speed, and low detection accuracy of the current train image fault detection model, a fast and lightweight train image fault detection model using convolutional neural network (FL-TINet) is proposed in this study. First, the joint depthwise separable convolution and divided-channel convolution strategy are applied to the feature extraction network in FL-TINet to reduce the number of parameters and computation amount in the backbone network, thereby increasing the detection speed. Second, a mixed attention mechanism is designed to make FL-TINet focus on key features. Finally, an improved discrete K-means clustering algorithm is designed to set the anchor boxes so that the anchor box can cover the object better, thereby improving the detection accuracy. Experimental results on PASCAL 2012 and train datasets show that FL-TINet can detect faults at 119 frames per second. Compared with the state-of-the-art CenterNet, RetinaNet, SSD, Faster R-CNN, MobileNet, YOLOv3, YOLOv4, YOLOv7Tiny, YOLOv8_n and YOLOX-Tiny models, FL-TINet's detection speed is increased by 96.37% on average, and it has higher detection accuracy and fewer parameters. The robustness test shows that FL-TINet can resist noise and illumination changes well.
Phosphorus-centered pnictogen bonds, similar to well-studied halogen bonds, play a vital role in molecular recognition and assembly. This study aims to explain how pnictogen bonds interact with other noncovalent inter...
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Phosphorus-centered pnictogen bonds, similar to well-studied halogen bonds, play a vital role in molecular recognition and assembly. This study aims to explain how pnictogen bonds interact with other noncovalent interactions. A model system, phosphines (PH3), which is also present in phosphorus cycles and reduces planetary atmospheres, is examined. The investigation of the phosphorus trifluoride (PF3) molecule explores its substituent effects. To generate a broad spectrum of molecular configurations, a specially tailored protocol for sampling and optimisation was implemented. The configurations were refined to uncover primary interaction patterns, and a clustering algorithm revealed unique interaction patterns. This report presents the energy stability and distribution of all the clusters. Our findings verify the prevalent presence of pnictogen bonds, identified by their geometric characteristics and co-occurrence with hydrogen bonds, which show an almost linear correlation. Another significant discovery is the correlation between various energy decomposition elements, especially regarding the electrostatic energy and overall binding energy. These results are anticipated to significantly contribute towards our comprehension of non-covalent interactions among phosphorus-containing molecules and the formulation of empirical models having physical interpretations.
Energy consumption is one of the most serious issues in designing Wireless Sensor Networks (WSNs) for maximizing its lifetime and stability. clustering is considered as one of the topology control methods for maintain...
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Energy consumption is one of the most serious issues in designing Wireless Sensor Networks (WSNs) for maximizing its lifetime and stability. clustering is considered as one of the topology control methods for maintaining the stability of WSNs which can significantly reduce energy consumption in WSNs. However, using different methods for the selection of cluster head is an important challenge in this domain of research. Load balanced clustering is known as an NP-hard problem for a WSN along with unequal load for sensor nodes. The Imperialist Competitive algorithm (ICA) is regarded as an evolutionary method which can be used for finding a quick and efficient solution to such problems. In this paper, a clustering method with an evolutionary approach is introduced which investigates the issues of load balance and energy consumption of WSNs in the equal and unequal load modes so as to select optimal cluster heads. Simulation of the proposed method, carried out via NS2, indicated that it improves the criteria of energy consumption, the number of active sensor nodes and execution time.
With the increase of space targets, it is significant to conduct rapid flyby monitoring of satellite clusters and identify Special Targets (STs), which have the distribution uncertainty among clusters. Moreover, there...
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With the increase of space targets, it is significant to conduct rapid flyby monitoring of satellite clusters and identify Special Targets (STs), which have the distribution uncertainty among clusters. Moreover, there are observation uncertainties during the flybys of space targets. In order to complete the flyby and observation mission more efficiently, the trajectory design of Observation Satellites (OSs) is constructed as a Mixed-Integer Nonlinear Programming (MINLP) model. A two-stage optimization method is proposed to solve the MultiSatellite Flyby (MSF) planning problem. For the first stage, an improved K-means algorithm is used to determine the target assignment groups and the orbital planes of OSs. For the second stage, the mixed integer Differential Evolution (DE) algorithm is utilized to optimize the flyby sequences and maneuver impulses, and to determine the initial orbit parameters of OSs, thereby obtaining the optimal probability of successful search. The simulation results show that the proposed method is effective and can obtain the optimal MSF trajectory under the velocity increment and time constraints, and that the increase of allowed maximum velocity increment could expand the mission benefits. Furthermore, compared with non-revisitable mode which is commonly used in multi-satellite visit problems, the revisitable mode shows the considerable advantage.
This paper presents a clustering algorithm for non-uniformly distributed point clouds in road scenes, which is used to alleviate the performance effect of classical Density-Based Spatial clustering of Applications wit...
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ISBN:
(纸本)9798400709234
This paper presents a clustering algorithm for non-uniformly distributed point clouds in road scenes, which is used to alleviate the performance effect of classical Density-Based Spatial clustering of Applications with Noise (DBSCAN) algorithm in non-uniformly distributed scenes. Because of the limitations of the DBSCAN algorithm, it's difficult to show good results in the space where the parameters aren't convergent. So we proposes a solution, which calculates the node density, average density, density variation coefficient and other parameters of each point which is divided the space into several small spaces with uniform density. Through this method we can achieve better clustering effect in small spaces. Finally, we analyze the proposed solution through Python code on some KITTI data sets. The analysis results show that our proposed scheme can effectively improve the performance of classical DBSCAN algorithm in non-density uniform space.
Addressing the poor resolution challenge of traditional Density-Based Spatial clustering of Applications with Noise (DBSCAN) algorithms in differentiating objects in close proximity, this paper introduces a multi-dime...
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ISBN:
(纸本)9798350389968
Addressing the poor resolution challenge of traditional Density-Based Spatial clustering of Applications with Noise (DBSCAN) algorithms in differentiating objects in close proximity, this paper introduces a multi-dimensional DBSCAN (MD-DBSCAN) clustering approach, considering the Doppler characteristics of millimeter wave (mmW) radar. Our approach is based on the idea that the whole clustering procedure is divided into two stages, i.e., velocity clustering and spatial one. Specifically, for each group, the clusters of varying radial velocities are firstly segmented, then followed by spatial dimension clustering. Experimental results demonstrate a 14.2% improvement in number of point clouds with this approach over traditional methods, underscoring its effectiveness in more accurately distinguishing closely situated objects in autonomous driving scenarios.
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