查看更多>>摘要：In this paper,we study the dimension estimate of global attractor for a 3D Brinkman-Forchheimer equation.Based on the differ-entiability of the semigroup with respect to the initial data,we show that the global attractor of strong solution of the 3D Brinkman-Forchheimer equation has finite Hausdorff and fractal dimensions.
查看更多>>摘要：In this paper,we generalize the renowned Ciric and Caristi type fixed point theorem and some corollaries.Then we give an ex-ample to illustrate our result is really better than the theorem.
查看更多>>摘要：Projective Reed-Solomon code is an important class of maximal distance separable codes in reliable communication and deep holes play important roles in its decoding.In this paper,we obtain two classes of deep holes of projective Reed-Solomon codes over finite fields with even characteristic.That is,let Fq be finite field with even characteristic,k ∈{2,q-2},and let u(x)be the Lagrange interpolation polynomial of the first q components of the received vector u∈Fqq+1.Suppose that the(q+l)-th component of u is 0,and u(x)=λxk+f≤k-2(x),λxq-2+f≤k-2(x),where A ∈ F*q,and f≤k-2(x)is a polynomial over Fq with degree no more than k-2.Then the received vector u is a deep hole of projective Reed-Solomon codes PRS(Fq,k).In fact,our result partially solved an open problem on deep holes of projective Reed-Solomon codes proposed by Wan in 2020.
查看更多>>摘要：Self-localization and orientation estimation are the essential capabilities for mobile robot navigation.In this article,a robust and real-time visual-inertial-GNSS(Global Navigation Satellite System)tightly coupled pose estimation(RRVPE)method for aerial robot navi-gation is presented.The aerial robot carries a front-facing stereo camera for self-localization and an RGB-D camera to generate 3D voxel map.Ulteriorly,a GNSS receiver is used to continuously provide pseudorange,Doppler frequency shift and universal time coordinated(UTC)pulse signals to the pose estimator.The proposed system leverages the Kanade Lucas algorithm to track Shi-Tomasi features in each video frame,and the local factor graph solution process is bounded in a circumscribed container,which can immensely abandon the compu-tational complexity in nonlinear optimization procedure.The proposed robot pose estimator can achieve camera-rate(30 Hz)performance on the aerial robot companion computer.We thoroughly experimented the RRVPE system in both simulated and practical circumstances,and the results demonstrate dramatic advantages over the state-of-the-art robot pose estimators.
查看更多>>摘要：News recommendation system is designed to deal with massive news and provide personalized recommendations for users.Ac-curately capturing user preferences and modeling news and users is the key to news recommendation.In this paper,we propose a new framework,news recommendation system based on topic embedding and knowledge embedding(NRTK).NRTK handle news titles that us-ers have clicked on from two perspectives to obtain news and user representation embedding:1)extracting explicit and latent topic features from news and mining users'preferences for them in historical behaviors;2)extracting entities and propagating users'potential preferences in the knowledge graph.Experiments in a real-world dataset validate the effectiveness and efficiency of our approach.
查看更多>>摘要：As deep learning models have made remarkable strides in numerous fields,a variety of adversarial attack methods have emerged to interfere with deep learning models.Adversarial examples apply a minute perturbation to the original image,which is incon-ceivable to the human but produces a massive error in the deep learning model.Existing attack methods have achieved good results when the network structure is known.However,in the case of unknown network structures,the effectiveness of the attacks still needs to be im-proved.Therefore,transfer-based attacks are now very popular because of their convenience and practicality,allowing adversarial samples generated on known models to be used in attacks on unknown models.In this paper,we extract sensitive features by Grad-CAM and pro-pose two single-step attacks methods and a multi-step attack method to corrupt sensitive features.In two single-step attacks,one corrupts the features extracted from a single model and the other corrupts the features extracted from multiple models.In multi-step attack,our method improves the existing attack method,thus enhancing the adversarial sample transferability to achieve better results on unknown models.Our method is also validated on CIFAR-10 and MINST,and achieves a l％-3％improvement in transferability.
查看更多>>摘要：With the development of information fusion,knowledge graph completion tasks have received a lot of attention.some studies investigate the broader underlying problems of linguistics,while embedding learning has a narrow focus.This poses significant challenges due to the heterogeneity of coarse-graining patterns.Then,to settle the whole matter,a framework for completion is designed,named Triple Encoder-Scoring Module(TEsm).The model employs an alternating two-branch structure that fuses local features into the interac-tion pattern of the triplet itself by perfectly combining distance and structure models.Moreover,it is mapped to a uniform shared space.Upon completion,an ensemble inference method is proposed to query multiple predictions from different graphs using a weight classifier.Experiments show that the experimental dataset used for the completion task is DBpedia,which contains five different linguistic subsets..Our extensive experimental results demonstrate that TEsm can efficiently and smoothly solve the optimal completion task,validating the performance of the proposed model.
查看更多>>摘要：Group sparse residual constraint with non-local priors(GSRC)has achieved great success in image restoration producing state-of-the-art performance.In the GSRC model,the l,norm minimization is employed to reduce the group sparse residual.In recent years,non-convex regularization terms have been widely used in image denoising problems,which have achieved better results in denoising than con-vex regularization terms.In this paper,we use the ratio of the l,and l2 norm instead of the l,norm to propose a new image denoising model,i.e.,a group sparse residual constraint model withl1/l2minimization(GSRC-l1/l2).Due to the computational difficulties arisen from the non-convexity and non-linearity,we focus on a constrained optimization problem that can be solved by alternative direction method of multipliers(ADMM).Experimental results of image denoising show that the pro-posed model outperforms several state-of-the-art image denoising methods both visually and quantitatively.
查看更多>>摘要：Sparse coding has achieved great success m various image restoration tasks.However,if the sparse representation coefficients of the structure(low-frequency information)and texture(high-frequency information)components of the image are under the same penalty constraint,the restoration effect may not be ideal.In this paper,an image denoising model combining mixed norm and weighted nuclear norm as regularization terms is proposed.The proposed model simultaneously exploits the group sparsity of the high frequency and low-rankness of the low frequency in dictionary-domain.The mixed norm is used to constrain the high frequency part and the weighted nuclear norm is used to constrain the low frequency part.In order to make the proposed model easy to solve under the framework of alternative di-rection multiplier method(ADMM),iterative shrinkage threshold method and weighted nuclear norm minimization method are used to solve the two sub-problems.The validity of the model is verified experimentally through comparison with some state-of-the-art methods.
查看更多>>摘要：In this research project,copper and stainless steel were connected by two laser welding methods:straight seam welding and swing welding.Then,electronic tensile test machine,X-ray diffractometer,scanning electron microscope and metallographic microscope were used to analyze the tensile properties,macroscopic and microscopic structure morphology and phase of the welded joint.Based on the experimental results,we determined that the strength of the straight seam welded joint was higher.Because of the intermetallic com-pound near the weld in the swing welding process,it leads to stress concentration,crack cracking and strength reduction.In addition,the oscillating laser beam also leads to the disorderly direction of columnar crystal and coarse structure,which makes the joint strength de-crease.
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