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Parallel hybrid iteration methods for block bordered linear systems

APPLIED MATHEMATICS AND COMPUTATION 1997年第1期86卷 37-60页

作者： Bai, ZZ State Key Laboratory of Scientific/Engineering Computing Institute of Computational Mathematics and Scientific/Engineering Computing Chinese Academy of Sciences P.O. Box 2719 Beijing 100080 People's Republic of China

A class of parallel hybrid iteration method and its accelerated overrelaxation variant are established for solving the large sparse block bordered system of linear equations, and their convergence are proved when the coefficient matrix of the linear system is an M-matrix, an II-matrix, and a symmetric positive definite matrix, respectively. (C) Elsevier Science Inc., 1997.

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computing Power in the Sky: Digital Twin-assisted Collaborative computing with Multi-UAV Networks

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IEEE Transactions on Vehicular Technology 2025年

作者： Wang, Chao Han, Yu Zhang, Long Jia, Ziye Zhang, Hongliang Hong, Choong Seon Han, Zhu Hebei University of Engineering School of Information and Electrical Engineering Handan056038 China Qilu University of Technology Shandong Academy of Sciences Key Laboratory of Computing Power Network and Information Security Ministry of Education Jinan250014 China Nanjing University of Aeronautics and Astronautics College of Electronic and Information Engineering Nanjing211106 China Southeast University National Mobile Communications Research Laboratory Jiangsu Nanjing211111 China Peking University State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Beijing100871 China Kyung Hee University Department of Computer Science and Engineering Gyeonggi-do Yongin-si17104 Korea Republic of University of Houston Department of Electrical and Computer Engineering HoustonTX77004 United States Kyung Hee University Department of Computer Science and Engineering Seoul446-701 Korea Republic of

The collaboration of computing powers (CPs) among unmanned aerial vehicles (UAVs)-mounted edge servers is essential to handle data-intensive tasks of user equipments (UEs). This paper presents a multi-UAV computing power network (CPN) that orchestrates the CP resources of edge servers to cooperatively process tasks through collaborative computing. Due to the frequent interactions among edge servers and the increased complexities for large-scale task executions, we propose a digital twin (DT)-driven multi-UAV CPN framework, where the aerial DT network is created as a digital replica of the multi-UAV network to assist collaborative computing. A joint optimization problem of the service association, offloading power control, task partitions, CP allocation, and UAV trajectory design is formulated to minimize the long-term average delay of UEs. We use the Lyapunov technique to tackle the long-term energy constraint, forming a tractable optimization problem, which is modeled as a Markov decision process to balance the UAV's deficit queue stability and the UE's task completion delay. A hybrid soft actor-critic based deep reinforcement learning algorithm is developed to optimize the joint design by sampling the hybrid action from the Gumbel and Gaussian distributions. Simulation results verify that the multi-UAV CPN contributes to significant performance gains when supported by DTs. © 2025 IEEE.

关键词： Markov processes

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Three-dimensional large eddy simulation and vorticity analysis of unsteady cavitating flow around a twisted hydrofoil

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Journal of Hydrodynamics 2013年第4期25卷 510-519页

作者：季斌罗先武彭晓星吴玉林 State Key Laboratory of Hydroscience and Engineering Tsinghua University China Ship Scientific Research Center

Large Eddy Simulation （LES） was coupled with a mass transfer cavitation model to predict unsteady 3-D turbulent cavita- ting flows around a twisted hydrofoil. The wall-adapting local eddy-viscosity （WALE） model was used to give the Sub-Grid Scale （SGS） stress term. The predicted 3-D cavitation evolutions, including the cavity growth, break-off and collapse downstream, and the shedding cycle as well as its frequency agree fairly well with experimental results. The mechanism for the interactions between the cavitation and the vortices was discussed based on the analysis of the vorticity transport equation related to the vortex stretching, volumetric expansion/contraction and baroclinic torque terms along the hydrofoil mid-plane. The vortical flow analysis demonstrates that cavitation promotes the vortex production and the flow unsteadiness. In non-cavitation conditions, the streamline smoothly passes along the upper wall of the hydrofoil with no boundary layer separation and the boundary layer is thin and attached to the foil except at the trailing edge. With decreasing cavitation number, the present case has O＂ = 1.07, and the attached sheet cavitation beco- mes highly unsteady, with periodic growth and break-off to form the cavitation cloud. The expansion due to cavitation induces boun- dary layer separation and significantly increases the vorticity magnitude at the cavity interface. A detailed analysis using the vorticity transport equation shows that the cavitation accelerates the vortex stretching and dilatation and increases the baroclinic torque as the major source of vorticity generation. Examination of the flow field shows that the vortex dilatation and baroclinic torque terms in- crease in the cavitating case to the same magnitude as the vortex stretching term, while for the non-cavitating case these two terms are zero.

关键词： cavitation Large Eddy Simulation (LES) hydrofoil vorticity analysis unsteady shedding

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On the regularity of trust region-cg algorithm: With application to deconvolution problem

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Science China Mathematics 2003年第3期46卷 312-325页

作者：王彦飞 Laboratory of Remote Sensing Information Sciences Institute of Remote Sensing ApplicationsChinese Academy of Sciences State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematicsand Scientific/Engineering ComputingAcademy of Mathematics and System SciencesChinese Academy of SciencesBeijing 100080China

Deconvolution problem is a main topic in signal processing. Many practical applications are re-quired to solve deconvolution problems. An important example is image reconstruction. Usually, researcherslike to use regularization method to deal with this problem. But the cost of computation is high due to thefact that direct methods are used. This paper develops a trust region-cg method, a kind of iterative methodsto solve this kind of problem. The regularity of the method is proved. Based on the special structure of thediscrete matrix, FFT can be used for calculation. Hence combining trust region-cg method with FFT is suitablefor solving large scale problems in signal processing.

关键词： ill-posed problems, efficient implementation, trust region-cg method, regularity.

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Software Vulnerability Mining and Analysis Based on Deep Learning

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Computers, Materials & Continua 2024年第8期80卷 3263-3287页

作者： Shibin Zhao Junhu Zhu Jianshan Peng State Key Laboratory of Mathematical Engineering and Advanced Computing Zhengzhou450001China

In recent years,the rapid development of computer software has led to numerous security problems,particularly software *** flaws can cause significant harm to users’privacy and *** security defect detection technology relies on manual or professional reasoning,leading to missed detection and high false detection *** intelligence technology has led to the development of neural network models based on machine learning or deep learning to intelligently mine holes,reducing missed alarms and false ***,this project aims to study Java source code defect detection methods for defects like null pointer reference exception,XSS(Transform),and Structured Query Language(SQL)***,the project uses open-source Javalang to translate the Java source code,conducts a deep search on the AST to obtain the empty syntax feature library,and converts the Java source code into a dependency *** feature vector is then used as the learning target for the neural *** types of Convolutional Neural Networks(CNN),Long Short-Term Memory(LSTM),Bi-directional Long Short-Term Memory(BiLSTM),and Attention Mechanism+Bidirectional LSTM,are used to investigate various code defects,including blank pointer reference exception,XSS,and SQL injection *** results show that the attention mechanism in two-dimensional BLSTM is the most effective for object recognition,verifying the correctness of the method.

关键词： Vulnerability mining software security deep learning static analysis

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An efficient quantum meet-in-the-middle attack against NTRU-2005

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Chinese Science Bulletin 2013年第28期58卷 3514-3518页

作者： WANG Hong MA Zhi MA ChuanGui State Key Laboratory of Mathematical Engineering and Advanced Computing

NTRU is one of the most widely used public-key cryptosystems and its security has been an active research *** paper proposes a new way to find NTRU-2005 private *** algorithm is based on meet-in-the-middle attack and a quantum algorithm for searching the fixed weight *** with the current classical and quantum meet-in-the-middle attacks,our algorithm has lower time and space ***,this attack can also be applied against different versions of *** result can help to understand the security of NTRU better.

关键词：中间人攻击量子算法 NTRU 空间复杂度公钥密码安全性私钥搜索

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Compact Arrayed Waveguide Gratings Fabricated on 800-nm-thick Si3N4 Photonic Integration Platform

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Journal of Lightwave Technology 2025年

作者： Fan, Zhuping Yan, Xiongshuo Li, Xuan Ma, Xiao Wang, Xuyang Zou, Jun Zhejiang University ZJU-Hangzhou Global Scientific and Technological Innovation Center Hangzhou311215 China Zhejiang University of Technology School of Physics Hangzhou310023 China Zhejiang University of Science and Technology School of Information & Electronic Engineering Hangzhou310023 China Shanxi University State Key Laboratory of Quantum Optics and Quantum Optics Devices Taiyuan030006 China

Silicon nitride (Si3N4) waveguide with thickness of > 600 nm having strong mode confinement and anomalous group velocity dispersion (GVD) has today become the leading photonic integration platform for linear and Kerr nonlinear photonics. However, due to the significant stress issue encountered in the deposition of thick Si3N4 film, there is a stringent requirement on the Si3N4 region with no etching. Hence it is very challenging to fabricate an arrayed waveguide grating (AWG) which has large potential applications for high-density integrated optical interconnect systems and on-chip filters (e.g., separate optical frequency comb signals), on the thick Si3N4 platform because of its large free propagation region (FPR). Here, for the first time to the best of our knowledge, we demonstrate an 8 × 8 100 GHz spacing AWG router and a 6 × 6 200 GHz spacing AWG multi/demultiplexer on the 800-nm-thick Si3N4 platform using a standard multi-project wafer (MPW) foundry process, by optimizing structural parameters. Both AWGs exhibit good performance with on-chip loss of ∼ 1.2 dB and small channel wavelength deviation of © 2025 IEEE. All rights reserved.

关键词： Silicon nitride

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Stego key searching for LSB steganography on JPEG decompressed image

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Science China(Information Sciences) 2016年第3期59卷 60-74页

作者： Jiufen LIU Yuguo TIAN Tao HAN Junchao WANG Xiangyang LUO Zhengzhou Information Science and Technology Institute State Key Laboratory of Mathematical Engineering and Advanced Computing

At present, steganalysis research focuses on detecting the existence of a hidden message. However,extracting the hidden information, i.e., an extracting attack, is crucial in obtaining effective evidence in computer forensics. Due to the difficulty of an extracting attack, research in this field is limited. In steganography with a stego key, an extracting attack is equivalent to recovering the stego key. In this paper we study a method for recovering the stego key in least significant bit(LSB) steganography with a decompressed JPEG image as the cover image. Firstly, the recovery of the stego key is translated into a cryptanalysis problem for a sequential cipher. The method for recovering the stego key is based on estimating the modification positions. The minimum size of the data used to recover the stego key successfully is discussed. Secondly, when a decompressed JPEG image is used as the cover image, the probability of recovering the cover pixels using recompression is *** is used to compute the error of the estimated sequence. Finally, an algorithm to recover the stego key in LSB steganography with a decompressed JPEG image as the cover image is proposed. The experimental results for the steganographic software, Hide and Seek 4.1 and its variant, which is a typical representative of LSB steganography, show that the proposed method can successfully recover the stego key in LSB replacement and LSB matching, i.e., the extracting attack is successful, and it outperforms three previous methods in terms of computational complexity.

关键词： steganalysis extracting attack LSB steganography decompressed JPEG image recompression stego key

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THE GLOBAL ATTRACTOR FOR A VISCOUS WEAKLY DISSIPATIVE GENERALIZED TWO-COMPONENT μ-HUNTER-SAXTON SYSTEM

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Acta Mathematica Scientia 2018年第2期38卷 651-672页

作者：张磊刘斌 School of Mathematics and Statistics Hubei Key Laboratory of Engineering Modeling and Scientific Computing Huazhong University of Science and Technology

This article is concerned with the existence of global attractor of a weakly dissipative generalized two-component μ-Hunter-Saxton （gμHS2） system with viscous terms. Under the period boundary conditions and with the help of the Galerkin procedure and compactness method, we first investigate the existence of global solution for the viscous weakly dissipative （gμHS2） system. On the basis of some uniformly prior estimates of the solution to the viscous weakly dissipative （gμHS2） system, we show that the semi-group of the solution operator {S（t）}t≥0 has a bounded absorbing set. Moreover, we prove that the dynamical system {S（t）}t≥0 possesses a global attractor in the Sobolev space H2（S） × H2（S）.

关键词： Generalized two-component μ-Hunter-Saxton system viscous weakly dissipative existence global attractor period boundary conditions

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Cryptanalysis of full PRIDE block cipher

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Science China(Information Sciences) 2017年第5期60卷 169-180页

作者： Yibin DAI Shaozhen CHEN State Key Laboratory of Mathematical Engineering and Advanced Computing Zhengzhou Information Science and Technology Institute

PRIDE is a lightweight block cipher proposed at CRYPTO 2014 by Albrecht et al., who claimed that the construction of linear layers is efficient and secure. In this paper, we investigate the key schedule and find eight 2-round iterative related-key differential characteristics, which can be used to construct 18-round related-key differentials. A study of the first subkey derivation function reveals that there exist three weak-key classes, as a result of which all the differences of subkeys for each round are identical. For the weak-key classes,we also find eight 2-round iterative related-key differential characteristics. Based on one of the related-key differentials, we launch an attack on the full PRIDE block cipher. The data and time complexity are 2;chosen plaintexts and 2;encryptions, respectively. Moreover, by using multiple related-key differentials, we improve the cryptanalysis, which then requires 2;chosen plaintexts and 2;encryptions, respectively. Finally, we use two 17-round related-key differentials to analyze full PRIDE, which requires 2;plaintexts and 2;*** are the first results on full PRIDE, and show that the PRIDE block cipher is not secure against related-key differential attack.

关键词： cryptanalysis block cipher PRIDE iterative characteristics related-key differential

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