Avoidance of topic drift and enabling crossing tunnels are two main difficulties in focused crawling. To overcome the problem of topic drift, we design a comprehensive priority evaluation (CPE) method based on the web text, anchor text, and context of hyperlinks, which improves the topic-relevance evaluation of unvisited hyperlinks. Subsequently, we propose an improved Bayesian classifier with weights (BCW), which adds label weights to the feature words of the Bayesian classifier to enhance the accuracy of webpage classification. To cross tunnels through which some topic-relevant webpages can be reached from low-relevance webpages, we construct a content block segmentation (CBS) technology for webpages based on the backtracking method, which segments a webpage into multiple blocks and then judges the relevance of every content block, extracting hyperlinks with high comprehensive relevance. Finally, a BCW-based focused crawling strategy combining the CPE and CBS strategies (BCW_CC) is proposed and experimentally evaluated for focused crawling in two domains: rainstorm disasters and sports. The results demonstrate the effectiveness of the developed BCW_CC method.

Evidence-based deep learning represents a burgeoning paradigm for uncertainty estimation, offering reliable predictions with negligible extra computational overheads. Existing methods usually adopt Kullback-Leibler divergence to estimate the uncertainty of network predictions, ignoring domain gaps among various modalities. To tackle this issue, this paper introduces a novel algorithm based on Hölder Divergence (HD) to enhance the reliability of multi-view learning by addressing inherent uncertainty challenges from incomplete or noisy data. Generally, our method extracts the representations of multiple modalities through parallel network branches, and then employs HD to estimate the prediction uncertainties. Through the Dempster-Shafer theory, integration of uncertainty from different modalities, thereby generating a comprehensive result that considers all available representations. Mathematically, HD proves to better measure the “distance” between real data distribution and predictive distribution of the model and improve the performances of multi-class recognition tasks. Specifically, our method surpasses the existing state-of-the-art counterparts on all evaluating benchmarks. We further conduct extensive experiments on different backbones to verify our superior robustness. It is demonstrated that our method successfully pushes the corresponding performance boundaries. Finally, we perform experiments on more challenging scenarios,i.e., learning with incomplete or noisy data, revealing that our method exhibits a high tolerance to such corrupted data.

An adaptive irregular constraint control problem is investigated in this study based on an output feedback control strategy. Nonlinear systems with irregular constraints are widely used in engineering fields such as the robot flexible operation. We consider such constraints referring to ones that may not only be asymmetric, but may also emerge in stages, or even be positive and negative at times. Ancillary constraint boundaries, which extend the originally imposed constraints to the full period of the system operation, are designed to accommodate the irregular constraints. Furthermore, the state observer is used to calculate the unmeasured states. Meanwhile, to get past the constraint that the nonlinearities in the system rely exclusively on the measured output, we employ the small-gain approach. Through the utilization of the input-state-practically stability (ISpS) theory, it is demonstrated that when the recommended adaptive control technique is applied, the system is semiglobal stable. Also, the output of the system follows the relevant trajectory. The validation of the findings from the simulation further highlights the advantages of the advised control program.

Inrecent years, significant progress has been made in the field of learning from positive and unlabeled examples (PU learning), particularly in the context of advancing image and text classification tasks. However, applying PU learning to semi-supervised disease classification remains a formidable challenge, primarily due to the limited availability of labeled medical images. In the realm of medical image-aided diagnosis algorithms, numerous theoretical and practical obstacles persist. The research on PU learning for medical image-assisted diagnosis holds substantial importance, as it aims to reduce the time spent by professional experts in classifying images. Unlike natural images, medical images are typically accompanied by a scarcity of annotated data, while an abundance of unlabeled cases exists. Addressing these challenges, this paper introduces a novel generative model inspired by Hölder divergence, specifically designed for semi-supervised disease classification using positive and unlabeled medical image data. In this paper, we present a comprehensive formulation of the problem and establish its theoretical feasibility through rigorous mathematical analysis. To evaluate the effectiveness of our proposed approach, we conduct extensive experiments on five benchmark datasets commonly used in PU medical learning: BreastMNIST, PneumoniaMNIST, BloodMNIST, OCTMNIST, and AMD. The experimental results clearly demonstrate the superiority of our method over existing approaches based on KL divergence. Notably, our approach achieves state-of-the-art performance on all five disease classification benchmarks. By addressing the limitations imposed by limited labeled data and harnessing the untapped potential of unlabeled medical images, our novel generative model presents a promising direction for enhancing semi-supervised disease classification in the field of medical image analysis.

Accurate point matching is widely used, and it is a critical and challenging process in feature-based image registration. To improve feature matching accuracy on putative matches with heavy outliers and similar local structures, an accurate and robust feature point matching algorithm based on minimum relative motion entropy (MRME) is proposed, in which the relative motion between the putative matches and their K-nearest neighbors is formulated. Based on the relative motion clustering result, the relative motion entropy is defined to find the coincident relative motions. According to relative motions with MRME, the outliers are removed in a two-stage feature match strategy. With quasi-linear time complexity, outliers with random or irregular relative motion are removed efficiently and accurately, while inliers with coincident relative motion are retained. Three data sets with repetitive patterns, viewpoint changes, low overlapping areas, and local deformations are used to demonstrate the performance of the proposed algorithm. MRME is shown to be more robust and accurate than ten state-of-the-art feature matching algorithms.

Due to the existence of repetitive patterns, ambiguous features, and similar local structures in remote sensing images, it is inevitable that the outliers with local pseudoisomorphic structures are preserved as inliers, which makes point matching still a challenging problem. To improve the accuracy of feature matching, a discriminative point matching algorithm named local structure consensus constraint is proposed to remove the outliers from putative correspondences and find two local structure consensus graphs composed of inliers. First, a local structure descriptor is proposed to evaluate the corresponding structure similarity of the K-nearest neighbors. Then, a cost function is defined to evaluate the local structure consistency. With a two-stage outlier removing strategy, the feature points with different local structures are eliminated, and two local structure consensus graphs are obtained. To evaluate the performance of the proposed algorithm, 45 aerial image pairs taken around the Shandong Peninsula with repetitive local patterns and ambiguous features are used. Compared with five state-of-the-art point matching methods, the proposed algorithm is proven to be more accurate and efficient.

The layout design of satellite modules is considered to be NP-hard. It is not only a complex coupled system design problem but also a special multi-objective optimization problem. The greatest challenge in solving this problem is that the function to be optimized is characterized by a multitude of local minima separated by high-energy barriers. The Wang-Landau (WL) sampling method, which is an improved Monte Carlo method, has been successfully applied to solve many optimization problems. In this paper we use the WL sampling method to optimize the layout of a satellite module. To accelerate the search for a global optimal layout, local search (LS) based on the gradient method is executed once the Monte-Carlo sweep produces a new layout. By combining the WL sampling algorithm, the LS method, and heuristic layout update strategies, a hybrid method called WL-LS is proposed to obtain a final layout scheme. Furthermore, to improve significantly the efficiency of the algorithm, we propose an accurate and fast computational method for the overlapping depth between two objects (such as two rectangular objects, two circular objects, or a rectangular object and a circular object) embedding each other. The rectangular objects are placed orthogonally. We test two instances using first 51 and then 53 objects. For both instances, the proposed WL-LS algorithm outperforms methods in the literature. Numerical results show that the WL-LS algorithm is an effective method for layout optimization of satellite modules.

Accurate point matching is a critical and challenging process in feature-based image registration. In this paper, a simple and robust feature point matching algorithm, called Restricted Spatial Order Constraints (RSOC), is proposed to remove outliers for registering aerial images with monotonous backgrounds, similar patterns, low overlapping areas, and large affine transformation. In RSOC, both local structure and global information are considered. Based on adjacent spatial order, an affine invariant descriptor is defined, and point matching is formulated as an optimization problem. A graph matching method is used to solve it and yields two matched graphs with a minimum global transformation error. In order to eliminate dubious matches, a filtering strategy is designed. The strategy integrates two-way spatial order constraints and two decision criteria restrictions, i.e., the stability and accuracy of transformation error. Twenty-nine pairs of optical and Synthetic Aperture Radar (SAR) aerial images are utilized to evaluate the performance. Compared with RANdom SAmple Consensus (RANSAC), Graph Transformation Matching (GTM), and Spatial Order Constraints (SOC), RSOC obtained the highest precision and stability.

Edge detection is a crucial approach for the location and acreage calculation of oil slick when oil spills on the sea. In this paper, in view of intensity inhomogeneity, high noise, and blurring of oil slick infrared (IR) aerial images, a novel algorithm is proposed to detect the edges of oil slick IR aerial images. In the proposed algorithm, we define an energy function model combining a region-scalable-fitting concept and a global minimization active contour (GMAC) model. The proposed novel algorithm avoids the existence of local minima and meanwhile deals with the intensity inhomogeneity, noise, and weak edge boundaries exiting in oil spill IR images. In the process of the active contour evolving toward object boundaries and numerical minimization, a dual formulation is used for overcoming drawbacks of the usual level set and gradient descent method so that the process of minimization can be much easier and our algorithm is independent of the initial position of the contour. Using the proposed algorithm, we can gain continuous and closed edges of oil slick IR aerial images. The experiment results have shown that the proposed algorithm outperforms conventional edge detection methods and other algorithms in terms of the efficiency and accuracy. In addition, the proposed algorithm is extended to synthetic-aperture-radar oil slick images, and satisfactory results of edge extraction can be obtained as well.