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Improving Performance of Virtual Machine Covert Timing Channel Through Optimized Run-Length Encoding

Journal of Computer Science & Technology 2023年第4期38卷 793-806页

作者：王翀陈荣亮古亮 Shenzhen Institute of Advanced Technology Chinese Academy of SciencesShenzhen 518055China Sangfor Technologies Inc. Shenzhen 518055China Shenzhen Key Laboratory for Exascale Engineering and Scientific Computing Shenzhen 518055China

With its wider acceptability,cloud can host a diverse set of data and applications ranging from entertainment to personal to *** foundation of cloud computing is based on virtual machines where boundaries among the application data are very thin,and the potential of data leakage exists all the *** instance,a virtual machine covert timing channel is an aggressive mechanism to leak confidential information through shared components or networks by violating isolation and security policies in *** performance of a covert timing channel(covert channel)is crucial to adversaries and attempts have been made to improve the performance of covert timing channels by advancing the encoding mechanism and covert information *** promising,the redundancy of the covert message is mainly *** paper applies three encoding schemes namely run-length,Huffman,and arithmetic encoding schemes for data compression of a virtual machine covert timing channel by exploiting ***,the paper studies the performance of such channels according to their ***,we show that these encoding schemes still contain redundancy in a covert channel scenario,and thereby a new encoding scheme namely optimized Runlength encoding(OptRLE)is presented that greatly enhances the performance of a covert timing *** optimizations schemes adopted by OptRLE are also discussed,and a mathematical model of the behavior of an OptRLE-based covert timing channel is *** theoretical capacity of a channel can be obtained using the proposed *** analysis reveals that OptRLE further improves the performance of a covert timing channel,in addition to the effects of the *** result shows how OptRLE affects the size of covert data and the capacity of covert timing channels,and why the performance of the covert timing channel is improved.

关键词： covert storage channel information security covert channel threat evaluation anti-detection criterion covert channel restriction

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Model-based Visual 3D Pose Tracking of Non-cooperative Spacecraft in Close Range 74

Model-based Visual 3D Pose Tracking of Non-cooperative Space...

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74th International Astronautical Congress, IAC 2023

作者： Liu, Chang Tang, Hao Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Guangdong Shenzhen518055 China Shenzhen Key Laboratory for Exascale Engineering and Scientific Computing Shenzhen China

This work proposes a new monocular algorithm to track the 3D pose of non-cooperative spacecraft for proximity operations in real time with the 3D boundaries and 3D contour of the spacecraft as features. The 3D boundary segments of the spacecraft are automatically extracted from the 3D spacecraft model a priori. At the beginning instant of tracking, the tracking system is initialized by a pose retrieval method. At the following time instant, with the initial pose and its covariance provided by the extended Kalman filter (EKF), the 3D contour segments are rapidly extracted from the 3D model. The boundary segments and contour segments are taken as 3D features. In the input image, we search the image data corresponding to the 3D features within the range decided by the initial pose and its covariance. Then, the spacecraft pose is determined in real time by minimizing the geometric distances of the 3D features to the back-projection lines of their corresponding image data. The covariance of the pose is estimated via the first-order optimal condition of the minimization. Eventually, the EKF is derived from the second-order autoregression (2nd-AR) to generate the final pose estimate, and the initial pose and its covariance for next time instant. The synthetic trials quantitatively indicate that our method can track the 3D pose of spacecraft in real time with high accuracy and has outstanding robustness to the dark occlusion, cluster background, large image distance, and image noise. The real trial qualitatively validates the effectiveness of our tracking method. Copyright © 2023 by the International Astronautical Federation (IAF). All rights reserved.

关键词： Kalman filter Pose determination Spacecraft Tracking

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Parallel Numerical Simulation of Blood Flows in Patient-specific Aortic Dissection 6

Parallel Numerical Simulation of Blood Flows in Patient-spec...

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6th IEEE International Conference on Computer and Communication Systems, ICCCS 2021

作者： Tu, Jiali Qin, Shanlin Chen, Rongliang Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen China University of Chinese Academy of Sciences Beijing China Shenzhen Key Laboratory for Exascale Engineering and Scientific Computing Shenzhen China

ISBN: (纸本)9780738126043

Aortic dissection is the separation of the inner layers of the aortic wall, which allows the blood to flow into it. The computational fluid dynamics allows a better understanding of its pathology and treatment. However, it is time-consuming due to the computationally expensive. In this work, we introduce a parallel algorithm for accurate and fast three-dimensional blood flow simulation of a patient-specific full-size aorta with dissections. Specifically, the unsteady Navier-Stokes equations are discretized by a unstructured finite element method in space and a fully implicit finite difference method in time, and the fully coupled nonlinear system at each time step is solved by a domain decomposition method based parallel scalable iterative algorithm. The numerical results are carefully analyzed and it shows that the simulated pressure, velocity, and wall shear stress are within a reasonable range. In addition, the algorithm achieves a parallel efficiency of 40% when using 3840 processor cores on the Tianhe-2A supercomputer, which shows the potential to do fast and high fidelity blood flow simulations of aortic dissection. © 2021 IEEE.

关键词： Iterative methods

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Parallel Numerical Simulation of Human Left Ventricular Diastole Based on Fluid-structure Interaction 6

Parallel Numerical Simulation of Human Left Ventricular Dias...

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6th IEEE International Conference on Computer and Communication Systems, ICCCS 2021

作者： Chang, Yujia Jiang, Yi Chen, Rongliang Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen China University of Chinese Academy of Sciences Beijing China Shenzhen Key Laboratory for Exascale Engineering and Scientific Computing Shenzhen China

ISBN: (纸本)9780738126043

In this paper, we propose a parallel fluid-structure interaction solution method for the simulation of the diastolic process of the human left ventricle. The three dimensional geometry of a patient-specific left ventricle is first segmented from a medical image, and then based on which an unstructured mesh is generated. The coupled fluid-structure interaction equations are spatially discretized by a finite element method on the unstructured mesh and a fully implicit scheme is introduced for the temporal discretization. At each timestep of the fully implicit method, a scalable parallel method is applied for solving the large scale nonlinear system. Numerical experiments show that the proposed method scales up to 1920 processor cores on the Tianhe-2A supercomputer for solving a problem with over 7.9 million unstructured tetrahedrons, which shows a potential to do high-fidelity simulation of human heart for clinical applications. © 2021 IEEE.

关键词： Finite element method

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Pose Estimation for Non-Cooperative Spacecraft Based on Deep Learning

SSRN

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SSRN 2024年

作者： Gao, Xiang Liu, Chang Liu, Jia Hu, Weiduo Shenzhen Aerospace Dongfanghong Satellite Ltd Guangdong Shenzhen518052 China Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Guangdong Shenzhen518052 China Beihang University Beijing100191 China Total Design Department Institute of Advanced Computing and Digital Engineering Shenzhen Key Laboratory for Exascale Engineering and Scientific Computing China School of Astronautics

This paper proposes an end-to-end pose estimation framework for spacecraft. The framework can run on full-size images and jointly calculate translation and rotation parameters based on shared features of convolutional network. In addition, we introduce the method of label normalization. In the training stage, images and labels are normalized and then input into the neural network architecture for training. In the test stage, the normalized images are input to the trained framework, and the corresponding predicted pose is obtained after the output parameters are reversely normalized. Then we use the local optimization method to optimize the predicted pose. The effectiveness of our method is verified by a large number of experiments. © 2024, The Authors. All rights reserved.

关键词： Network architecture

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On eigenvalues of a high-dimensional Kendall's rank correlation matrix with dependence

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Science China Mathematics 2023年第11期66卷 2615-2640页

作者： Zeng Li Cheng Wang Qinwen Wang Department of Statistics and Data Science Southern University of Science and TechnologyShenzhen 518055China School of Mathematical Sciences Shanghai Jiao Tong UniversityShanghai 200240China Key Laboratory of Scientific and Engineering Computing(Shanghai Jiao Tong University) Shanghai 200240China School of Data Science Fudan UniversityShanghai 200433China

In this paper,we investigate the limiting spectral distribution of a high-dimensional Kendall’s rank correlation *** underlying population is allowed to have a general dependence *** result no longer follows the generalized Marcenko-Pastur law,which is brand *** is the first result on rank correlation matrices with *** applications,we study Kendall’s rank correlation matrix for multivariate normal distributions with a general covariance *** these results,we further gain insights into Kendall’s rank correlation matrix and its connections with the sample covariance/correlation matrix.

关键词： Hoeffding decomposition Kendall's rank correlation matrix limiting spectral distribution random matrix theory

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HPE Transformer: Learning to Optimize Multi-Group Multicast Beamforming Under Nonconvex QoS Constraints

arXiv

引用

arXiv 2024年

作者： Li, Yang Liu, Ya-Feng The Shenzhen Research Institute of Big Data Shenzhen518172 China The State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China

This paper studies the quality-of-service (QoS) constrained multi-group multicast beamforming design problem, where each multicast group is composed of a number of users requiring the same content. Due to the nonconvex QoS constraints, this problem is nonconvex and NP-hard. While existing optimization-based iterative algorithms can obtain a suboptimal solution, their iterative nature results in large computational complexity and delay. To facilitate real-time implementations, this paper proposes a deep learning-based approach, which consists of a beamforming structure assisted problem transformation and a customized neural network architecture named hierarchical permutation equivariance (HPE) transformer. The proposed HPE transformer is proved to be permutation equivariant with respect to the users within each multicast group, and also permutation equivariant with respect to different multicast groups. Simulation results demonstrate that the proposed HPE transformer outperforms state-of-the-art optimization-based and deep learning-based approaches for multi-group multicast beamforming design in terms of the total transmit power, the constraint violation, and the computational time. In addition, the proposed HPE transformer achieves pretty good generalization performance on different numbers of users, different numbers of multicast groups, and different signal-to-interference-plus-noise ratio targets. Copyright © 2024, The Authors. All rights reserved.

关键词： Beamforming

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QoS-Based Beamforming and Compression Design for Cooperative Cellular Networks via Lagrangian Duality

引用

IEEE Transactions on Signal Processing 2025年

作者： Fan, Xilai Liu, Ya-Feng Liu, Liang Chang, Tsung-Hui Chinese Academy of Sciences State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and Systems Science Beijing100190 China The Hong Kong Polytechnic University Department of Electronic and Information Engineering Hong Kong Hong Kong The Chinese University of HongKong School of Science and Engineering Shenzhen Shenzhen China Shenzhen Research Institute of Big Data China

This paper considers the quality-of-service (QoS)-based joint beamforming and compression design problem in the downlink cooperative cellular network, where multiple relay-like base stations (BSs), connected to the central processor via ratelimited fronthaul links, cooperatively transmit messages to the users. The problem of interest is formulated as the minimization of the total transmit power of the BSs, subject to all users' signal-to-interference-plus-noise ratio (SINR) constraints and all BSs' fronthaul rate constraints. In this paper, we first show that there is no duality gap between the considered joint optimization problem and its Lagrangian dual by showing the tightness of its semidefinite relaxation (SDR). Then, we propose an efficient algorithm based on the above duality result for solving the considered problem. The proposed algorithm judiciously exploits the special structure of an enhanced Karush-Kuhn-Tucker (KKT) conditions of the considered problem and approaches the solution that satisfies the enhanced KKT conditions via two fixed point iterations. Two key features of the proposed algorithm are: (1) it is able to detect whether the considered problem is feasible or not and find its globally optimal solution when it is feasible;(2) it is highly efficient because both of the fixed point iterations in the proposed algorithm are linearly convergent and function evaluations in the fixed point iterations are computationally cheap. Numerical results show the global optimality and efficiency of the proposed algorithm. © 1991-2012 IEEE.

关键词： Lagrange multipliers

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Covariance-Based Device Activity Detection with Massive MIMO for Near-Field Correlated Channels

arXiv

引用

arXiv 2024年

作者： Wang, Ziyue Li, Yang Liu, Ya-Feng Ma, Junjie The State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China The Shenzhen Research Institute of Big Data Shenzhen518172 China The School of Science and Engineering The Chinese University of Hong Kong Shenzhen518172 China

This paper studies the device activity detection problem in a massive multiple-input multiple-output (MIMO) system for near-field communications (NFC). In this system, active devices transmit their signature sequences to the base station (BS), which detects the active devices based on the received signal. In this paper, we model the near-field channels as correlated Rician fading channels and formulate the device activity detection problem as a maximum likelihood estimation (MLE) problem. Compared to the traditional uncorrelated channel model, the correlation of channels complicates both algorithm design and theoretical analysis of the MLE problem. On the algorithmic side, we propose two computationally efficient algorithms for solving the MLE problem: an exact coordinate descent (CD) algorithm and an inexact CD algorithm. The exact CD algorithm solves the one-dimensional optimization subproblem exactly using matrix eigenvalue decomposition and polynomial root-finding. By approximating the objective function appropriately, the inexact CD algorithm solves the one-dimensional optimization subproblem inexactly with lower complexity and more robust numerical performance. Additionally, we analyze the detection performance of the MLE problem under correlated channels by comparing it with the case of uncorrelated channels. The analysis shows that when the overall number of devices N is large or the signature sequence length L is small, the detection performance of MLE under correlated channels tends to be better than that under uncorrelated channels. Conversely, when N is small or L is large, MLE performs better under uncorrelated channels than under correlated ones. Simulation results demonstrate the computational efficiency of the proposed algorithms and verify the correctness of the analysis. Copyright © 2024, The Authors. All rights reserved.

关键词： Eigenvalues and eigenfunctions

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Joint Design of Radar Receive Filter and Unimodular ISAC Waveform with Sidelobe Level Control

arXiv

引用

arXiv 2025年

作者： Zhang, Kecheng Liu, Ya-Feng Wang, Zhongbin Yuan, Weijie Keskin, Musa Furkan Wymeersch, Henk Xia, Shuqiang School of System Design and Intelligent Manufacturing The Shenzhen Key Laboratory of Robotics and Computer Vision Southern University of Science and Technology Shenzhen518055 China State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China Department of Electrical Engineering Chalmers University of Technology Gothenburg41296 Sweden ZTE Corporation The State Key Laboratory of Mobile Network and Mobile Multimedia Technology Shenzhen518055 China

Integrated sensing and communication (ISAC) has been considered a key feature of next-generation wireless networks. This paper investigates the joint design of the radar receive filter and dual-functional transmit waveform for the multiple-input multiple-output (MIMO) ISAC system. While optimizing the mean square error (MSE) of the radar receive spatial response and maximizing the achievable rate at the communication receiver, besides the constraints of full-power radar receiving filter and unimodular transmit sequence, we control the maximum range sidelobe level, which is often overlooked in existing ISAC waveform design literature, for better radar imaging performance. To solve the formulated optimization problem with convex and nonconvex constraints, we propose an inexact augmented Lagrangian method (ALM) algorithm. For each subproblem in the proposed inexact ALM algorithm, we custom-design a block successive upper-bound minimization (BSUM) scheme with closed-form solutions for all blocks of variable to enhance the computational efficiency. Convergence analysis shows that the proposed algorithm is guaranteed to provide a stationary and feasible solution. Extensive simulations are performed to investigate the impact of different system parameters on communication and radar imaging performance. Comparison with the existing works shows the superiority of the proposed algorithm. © 2025, CC BY-NC-SA.

关键词： Mean square error

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