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arXiv 2019年

作者： Polak, Daniel Chatnuntawech, Itthi Yoon, Jaeyeon Iyer, Siddharth Srinivasan Lee, Jongho Bachert, Peter Adalsteinsson, Elfar Setsompop, Kawin Bilgic, Berkin Department of Physics and Astronomy Heidelberg University Heidelberg Germany Department of Radiology A. A. Martinos Center for Biomedical Imaging Massachusetts General Hospital CharlestownMA United States Siemens Healthcare GmbH Erlangen Germany National Nanotechnology Center Pathum Thani Thailand Department of Electrical and Computer Engineering Laboratory for Imaging Science and Technology Seoul National University Seoul Korea Republic of Department of Electronical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA United States Medical Physics in Radiology Heidelberg Germany Harvard Medical School BostonMA United States Massachusetts Institute of Technology Harvard-MIT Health Sciences and Technology CambridgeMA United States

We propose Nonlinear Dipole Inversion (NDI) for high-quality Quantitative Susceptibility Mapping (QSM) without regularization tuning, while matching the image quality of state-of-the-art reconstruction techniques. In addition to avoiding over-smoothing that these techniques often suffer from, we also obviate the need for parameter selection. NDI is flexible enough to allow for reconstruction from an arbitrary number of head orientations, and outperforms COSMOS even when using as few as 1-direction data. This is made possible by a nonlinear forward-model that uses the magnitude as an effective prior, for which we derived a simple gradient descent update rule. We synergistically combine this physics-model with a Variational Network (VN) to leverage the power of deep learning in the VaNDI algorithm. This technique adopts the simple gradient descent rule from NDI and learns the network parameters during training, hence requires no additional parameter tuning. Further, we evaluate NDI at 7T using highly accelerated Wave-CAIPI acquisitions at 0.5 mm isotropic resolution and demonstrate high-quality QSM from as few as 2-direction data. Copyright © 2019, The Authors. All rights reserved.

关键词： Gradient methods

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Research on Co-Location Privacy-Preserving System

Research on Co-Location Privacy-Preserving System

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International Conference on Mobile Ad-hoc and Sensor Networks, MSN

作者： Jiachun Li Dongqing Xiong Jianzhou Cao Communication & Computer Network Lab of GD South China University of Technology Guangzhou P.R. China Guangdong Mechanical & Electronical College of Technology Guangzhou PR. China School of Computer Science & Engineering South China University of Technology Guangzhou P.R. China

ISBN: (纸本)9781728105499;9781728105482

With the deep integration of mobile, social and location, users share information with location tags and friends labels in mobile social networks, which could result in the disclosure of location privacy of the users and their friends. Because of the complexity of social circles and the difference of relation strength, users have different location privacy-preserving requirements for different friends. Existing location privacy protection methods and mobile social network services pay less attention to the co-location information attack called CF attack for short. A co-location privacy-preserving system framework is proposed, the key technologies of core module called location privacy-preserving agent are explored, novel calculation method of relation strength based on bi-direction interaction frequency between user and friends is given, and two location privacy-preserving algorithms as a defence against CF attack are designed in the paper, which are LPPC based on the user's coordination and CCTA based on the co-location information concealment and time adjustment. Experimental tests on real data sets show that algorithms proposed could be suitable for different location privacy-preserving scenarios and reflect the mapping between intimacy and privacy-preserving requirement effectively, and the system framework could be extended to the location privacy-preserving application for any mobile social network services.

关键词： Privacy Data privacy Servers Ions Bidirectional control Twitter

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Opportunistic Downlink Interference Alignment for Multi-Cell MIMO Networks

Opportunistic Downlink Interference Alignment for Multi-Cell...

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作者： Yang, Hyun Jong Shin, Won-Yong Jung, Bang Chul Suh, Changho Paulraj, Arogyaswami School of Electronical and Computer Engineering Ulsan National Institute of Science and Technology Ulsan44919 Korea Republic of Department of Computer Science and Engineering Dankook University Yongin16890 Korea Republic of Department of Electrical Engineering Chungnam National University Daejeon34134 Korea Republic of Department of Electrical Engineering Korea Advanced Institute of Science and Technology Daejeon34141 Korea Republic of Department of Electrical Engineering Stanford University StanfordCA94305 United States

In this paper, we propose an opportunistic downlink interference alignment (ODIA) for interference-limited cellular downlink, which intelligently combines user scheduling and downlink IA techniques. The proposed ODIA not only efficiently reduces the effect of inter-cell interference from other-cell base stations (BSs) but also eliminates intra-cell interference among spatial streams in the same cell. We show that the minimum number of users required to achieve a target degrees-of-freedom can be fundamentally reduced, i.e., the fundamental user scaling law can be improved by using the ODIA, compared with the existing downlink IA schemes. In addition, we adopt a limited feedback strategy in the ODIA framework, and then analyze the number of feedback bits required for the system with limited feedback to achieve the same user scaling law of the ODIA as the system with perfect channel state information. We also modify the original ODIA in order to further improve the sum-rate, which achieves the optimal multiuser diversity gain, i.e., log log N , per spatial stream even in the presence of downlink inter-cell interference, where N denotes the number of users in a cell. Simulation results show that the ODIA significantly outperforms existing interference management techniques in terms of sum rate in realistic cellular environments. Note that the ODIA operates in a non-collaborative and decoupled manner, i.e., it requires no information exchange among BSs and no iterative beamformer optimization between BSs and users, thus leading to an easier implementation. © 2017 IEEE.

关键词： Degrees of freedom (mechanics)

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Precision Tracking Control of Piezoelectric Actuator using a Hammerstein-based dynamic Hysteresis Model 35

Precision Tracking Control of Piezoelectric Actuator using a...

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第35届中国控制会议

作者： WANG ZhenYan ZHANG Zhen ZHOU KeMin School of Electronical and Information Engineering Taiyuan University of Science and Technology School of Automation Science and Electrical Engineering Bei Hang University School of Electrical Engineering Southwest Jiaotong University School of Electrical Engineering and Computer Science Louisiana State University

ISBN: (纸本)9789881563910

Piezoelectric actuator has been frequently utilized in the micromanipulation control. However, the rate-dependent hysteresis properties in the actuator affect severely the high precision tracking control. In this study, a Hammerstein-based model with Bouc-Wen hysteresis nonlinearity is proposed to describe the dynamic characteristics of rate-dependent hysteresis in a piezoelectric actuator. The Bouc-Wen model parameters and the linear dynamic block parameters are identified respectively by particle swarm optimization algorithm and recursive least squares algorithm. Based on the proposed dynamic model, a new control scheme with a hysteresis compensator is developed for precise tracking control of the actuator. To verify the effectiveness of the proposed rate-dependent modeling and control scheme in practical application, an experiment of a piezoelectric actuator is implemented by d SPACE with the frequency excitation range of 1-100 Hz. The experimental results show that the relative error of tracking control is less than 8% for both single frequencies and compound frequencies in the given frequency range.

关键词： piezoelectric actuator rate-dependent hysteresis Bouc-Wen Hammerstein model

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Topology-Based and Event-Oriented Approach to Simulation of Cyber-Physical Systems

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Journal of Donghua University(English Edition) 2016年第6期33卷 991-996页

作者： ZHENG Jun-xi ZHANG Ping JIN Pei-gen LI Fang DU Guang-long School of Computer Science and Engineering South China University of Technology Guangzhou 510001 China School of Information Engineering Guangdong Mechanical and Electronical College Guangzhou 510515 China

A simulation model for cyber-physical systems(CPSs)was *** model was developed by the method of combination of topology-based and event-oriented that could be used to simulate systems with routing flexibility,service-selection flexibility and service- mode flexibility overall by integrating the strategies *** validity of the model has been verified by two extensive experiments.

关键词： topological-based event-oriented cyber-physical systems discrete event systems simulation model

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A METHOD OF TASK ALLOCATION AND AUTOMATED NEGOTIATION FOR MULTI ROBOTS

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Journal of Electronics(China) 2012年第6期29卷 541-549页

作者： Ke Wende Peng Zhiping Yuan Quande Hong Bingrong Chen Ke Cai Zesu Department of Computer Science Guangdong University of Petrochemical Technology School of Computer Science Harbin Institute of Technology School of Electronical and Information Engineering Changchun Institute of Technology

A method of task allocation and automated negotiation for multi robots was proposed. Firstly, the principles of task allocation were described based on the real capability of robot. Secondly, the model of automated negotiation was constructed, in which Least-Squares Support Vector Regression (LSSVR) was improved to estimate the opponent's negotiation utility and the robust controller of output feedback was employed to optimize the utility performance indicators. Thirdly, the protocol of negotiation and reallocation was proposed to improve the real-time capability and task allocation. Finally, the validity of method was proved through experiments.

关键词： Distributed Robot Task allocation Negotiation Communication

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Mental imagery - The cognitive maps of memory retrieval based on statistical graphs

Mental imagery - The cognitive maps of memory retrieval base...

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6th International Conference on Complex Medical engineering, CME 2012

作者： Li, Mi Han, Dongning Lu, Shengfu Zhong, Ning School of Computer and Communication Engineering Liaoning ShiHua University Liaoning China International WIC Institute Beijing University of Technology Beijing China College of Optical and Electronical Information Changchun University of Science and Technology Jilin China

ISBN: (纸本)9781467316163

Statistical graph is widely used to represent quantitative data in science, business, and many other fields in our daily life. To the best of our knowledge, the neural mechanisms underlying memory retrieval based on statistical graphs have not been reported yet. We investigated this issue using functional magnetic resonance imaging (fMRI). In our study, 36 normal subjects were instructed to read statistical information that was visually presented in either statistical graph or text. Then the reading stimuli disappeared, subjects were instructed to answer a question that needed to retrieval information of the content of the statistical graph or text. The direct comparison of the memory retrieval based on statistical graphs and that based on text showed that there were significantly more activated the lateral regions including ventral and dorsal pathways, as well as the parietal-temporal-occipital (PTO) association area (BA19/39);the medial regions including parahippocampal cortex (PHC) and retrosplenial complex (RSC). The results suggest that the two visual pathways and the PTO are involved in forming the imagery of statistical graphs, and the PHC and RSC are involved in the memory retrieval that played on the mental imagery of statistical graphs, in which PHC is involved in the retrieval of object-location associations and RSC is involved in orientation mechanisms. Previous studies demonstrated that spatial navigation was also composed of two similar processes: retrieval of object-location associations and orientation. We propose that memory retrieval based on statistical graphs draws on similar processing in spatial navigation that is based on the cognitive maps. © 2012 IEEE.

关键词： Graphic methods

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Fast Monotonic Blind Deconvolution Algorithm for Constrained TV Based Image Restoration

Fast Monotonic Blind Deconvolution Algorithm for Constrained...

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World Congress on Intelligent Control and Automation

作者： Haiying Liu W. S. Lu Yanan Fu Yu Cheng Tingfang Yan Teng Li Max Q. H. Meng School of Control Science and Engineering Shandong University Dept. of Electrical and Computer Engineering University of Victoria Department of Electronical Engineering Chinese University of Hong Kong

ISBN: (纸本)9781467313971

A new fast monotonic blind deconvolution algorithmic method is investigated based on the constrained variational minimization framework under the periodic boundary conditions. The contributions of our methodology are that the blur operator identification and image restoration can be simultaneously optimized even under high noise level as compared to previous methods. Specifically, the monotone fast iterative shrinkage/thresholding algorithm (MFISTA) combined with the fast gradient projection (FGP) algorithm, is extended to deal with our new proposed algorithm and guarantee the monotonic convergence rate. In addition, the deblurring subproblem is enhanced by incorporating a bisection technique to effectively identify a near optimal value for the regularization parameter of the TV-Frobenius objective function quickly and accurately. Initial experimental results for gray satellite and color wireless capsule endoscopy (WCE) images demonstrate the considerable performance of the proposed algorithm.

关键词： Blind Deconvolution Total Variation De-blurring Denoising Bisection Technique

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Associative information processing in parahippocampal place area (PPA): An fMRI study

Associative information processing in parahippocampal place ...

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2012 International Conference on Brain Informatics, BI 2012

作者： Li, Mi Han, Dongning Lu, Shengfu Liu, Zheng Zhong, Ning School of Computer and Communication Engineering Liaoning ShiHua University Liaoning 113001 China International WIC Institute Beijing University of Technology Beijing 100024 China College of Optical and Electronical Information Changchun University of Science and Technology Jilin 130022 China Dept. of Biomedical Engineering Tianjing University Tianjing 300072 China Dept. of Life Science and Informatics Maebashi Institute of Technology Maebashi-City 371-0816 Japan Beijing Key Laboratory of MRI and Brain Informatics China

ISBN: (纸本)9783642351389

The function of the parahippocampal place area (PPA) is a matter of debate. We investigated this issue in fMRI experiment by 36 normal subjects using two types of tasks: figure and text. Furthermore, the figure tasks contain two kinds of contextual associations: one is among items;the other is among items and their locations which refers to the spatial contextual associations. In contrast, the text tasks contain only item contextual associations - they do not have any spatial information. The results showed that the right PPA located at anterior lingual gyrus and left anterior parahippocampal gyrus nearby amygdala were significantly activated during both figure and text tasks, which indicate that the PPA is more involved in associative information processing. © 2012 Springer-Verlag.

关键词： Associative processing

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Mental imagery—The cognitive maps of memory retrieval based on statistical graphs

Mental imagery—The cognitive maps of memory retrieval based...

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IEEE/ICME International Conference on Complex Medical engineering, CME

作者： Mi Li Dongning Han Shengfu Lu Ning Zhong The International WIC Institute Beijing University of Technology Beijing China The School of Computer and Communication Engineering Liaoning ShiHua University Liaoning China College of Optical and Electronical Information Changchun University of Science and Technology Jilin China

Statistical graph is widely used to represent quantitative data in science, business, and many other fields in our daily life. To the best of our knowledge, the neural mechanisms underlying memory retrieval based on statistical graphs have not been reported yet. We investigated this issue using functional magnetic resonance imaging (fMRI). In our study, 36 normal subjects were instructed to read statistical information that was visually presented in either statistical graph or text. Then the reading stimuli disappeared, subjects were instructed to answer a question that needed to retrieval information of the content of the statistical graph or text. The direct comparison of the memory retrieval based on statistical graphs and that based on text showed that there were significantly more activated the lateral regions including ventral and dorsal pathways, as well as the parietal-temporal-occipital (PTO) association area (BA19/39); the medial regions including parahippocampal cortex (PHC) and retrosplenial complex (RSC). The results suggest that the two visual pathways and the PTO are involved in forming the imagery of statistical graphs, and the PHC and RSC are involved in the memory retrieval that played on the mental imagery of statistical graphs, in which PHC is involved in the retrieval of object-location associations and RSC is involved in orientation mechanisms. Previous studies demonstrated that spatial navigation was also composed of two similar processes: retrieval of object-location associations and orientation. We propose that memory retrieval based on statistical graphs draws on similar processing in spatial navigation that is based on the cognitive maps.

关键词： Navigation High definition video Ear Educational institutions

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