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arXiv 2019年

作者： Di, Boya Zhang, Hongliang Song, Lingyang Li, Yonghui Han, Zhu Vincent Poor, H. Department of Electronics Engineering Peking University Beijing China Department of Computing Imperial College London London United Kingdom Department of Electronical and Computer Engineering University of Houston HoustonTX United States School of Electrical and Information Engineering University of Sydney Australia School of Engineering and Applied Science Princeton University NY United States

Reconfigurable intelligent surface (RIS) has drawn considerable attention from the research society recently, which creates favorable propagation conditions by controlling the phase shifts of the reflected waves at the surface, thereby enhancing wireless transmissions. In this paper, we study a downlink multi-user system where the transmission from a multi-antenna base station (BS) to various users is achieved by the RIS reflecting the incident signals of the BS towards the users. Unlike most existing works, we consider the practical case where only a limited number of discrete phase shifts can be realized by the finite-sized RIS. Based on the reflection-dominated one-hop propagation model between the BS and users via the RIS, a hybrid beamforming scheme is proposed and the sum-rate maximization problem is formulated. Specifically, the continuous digital beamforming and discrete RIS-based analog beamforming are performed at the BS and the RIS, respectively, and an iterative algorithm is designed to solve this problem. Both theoretical analysis and numerical validations show that the RIS-based system can achieve a good sum-rate performance by setting a reasonable size of RIS and a small number of discrete phase shifts. Copyright © 2019, The Authors. All rights reserved.

关键词： Iterative methods

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Industrial Wireless LAN System Compatible with Asynchronous Communication

Industrial Wireless LAN System Compatible with Asynchronous ...

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2018 International Symposium on Intelligent Signal Processing and Communication Systems, ISPACS 2018

作者： Tsurita, Makoto Ochi, Hiroshi Sakamoto, Kyoshiro Toyofuku, Mizuki Itou, Yoshiki Nguyen, Tran Thi Thao Uwai, Tatsumi Nagao, Yuhei Kurosaki, Masayuki Sai, Baiko Graduate Shcool of Computer Science and Systems Engineering Kyushu Institute of Technology 680-4 Kawazu Iizuka Fukuoka820-8502 Japan Daiichi Institute of Technology Department of Information Technology and Electronical Engineering 1-10-2 Kokubu-chuo Kirishima Kagoshimag899-4395 Japan

ISBN: (纸本)9781538657713

In this research, we propose an industrial Wireless Local Area Network (iWLAN) system compatible with asynchronous communication for industrial robots (iRBs) control in factory automation (FA) environments. In FA, iRBs are not only controlled by synchronous communication but also by asynchronous communication. As our conventional system is not compatible with asynchronous communication, it causes delay when iRBs are controlled by asynchronous communication. In order to target iRBs using asynchronous communication, we propose the utilization of specific memory writing technique. The register transfer level (RTL) simulation results show that our proposals can communicate with iRBs in faster throughput, better than the conventional system. Furthermore, the field-programmable gate array (FPGA) implementation are carried out to confirm that motors can be controlled by our iWLAN system compatible with asynchronous communication. © 2018 IEEE.

关键词： Industrial robots

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Bimodal stereo: Joint shape and pose estimation from color-depth image pair

arXiv

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arXiv 2019年

作者： Zhang, Chi Liu, Yuehu Wu, Ying Zhang, Qilin Wang, Le Institute of Artificial Intelligence and Robotics Xi'an Jiaotong University No.28 Xianning West Road Xi'an Shaanxi China Department of Electronical Engineering and Computer Science Northwestern University 2145 Sheridan Road EvanstonIL60208 United States HERE Technologies 425 W Randolph St ChicagoIL60606 United States

Mutual calibration between color and depth cameras is a challenging topic in multi-modal data registration. In this paper, we are confronted with a "Bimodal Stereo" problem, which aims to solve camera pose from a pair of an uncalibrated color image and a depth map from different views automatically. To address this problem, an iterative Shape-from-Shading (SfS) based framework is proposed to estimate shape and pose simultaneously. In the pipeline, the estimated shape is refined by the shape prior from the given depth map under the estimated pose. Meanwhile, the estimated pose is improved by the registration of estimated shape and shape from given depth map. We also introduce a shading based refinement in the pipeline to address noisy depth map with holes. Extensive experiments showed that through our method, both the depth map, the recovered shape as well as its pose can be desirably refined and recovered. Copyright © 2019, The Authors. All rights reserved.

关键词： Pipelines

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Nonlinear dipole inversion (ndi) enables quantitative susceptibility mapping (qsm) without parameter tuning

arXiv

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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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Improvement of microwave heating uniformity via shelled processing

Improvement of microwave heating uniformity via shelled proc...

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2017 International Applied Computational Electromagnetics Society Symposium in China, ACES-China 2017

作者： Hong, Tao Tang, Zhengming Yang, Yong Zhu, Huacheng Huang, Kama College of Electronical Information Engineering China West Normal University Nanchong637002 China College of Computer Science and Technology China University of Mining and Technology Xuzhou221116 China Colledge of Electronics and Information Engineering Sichuan University Chengdu610065 China

ISBN: (纸本)9780996007856

As an efficient and clean energy, microwaves have been widely used for industrial production. However, hot spots and thermal runaway have prevented the large-scale application of microwaves. In this paper, a new multiphysics model is proposed to solve the problem of non-uniform heating. In this model, electromagnetics and heat transfer are coupled to simulate the heating process. The sample is wrapped by shells in order to get more uniform electric filed distribution. The heating uniformities of shelled and non-shelled samples are discussed by considering different sizes of samples and shells. The results show that the shelled processing can obviously improve the heating uniformity of microwaves. © 2017 Applied Computational Electromagnetics Society.

关键词： Microwaves

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Improvement of Microwave Heating Uniformity via Shelled Processing

Improvement of Microwave Heating Uniformity via Shelled Proc...

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International Applied Computational Electromagnetics Society Symposium in China

作者： Tao Hong Zhengming Tang Yong Yang Huacheng Zhu Kama Huang College of Electronical Information Engineering China West Normal University College of Computer Science and Technology China University of Mining and Technology Colledge of Electronics and Information Engineering Sichuan University

ISBN: (纸本)9781509043118

关键词： Electromagnetic heating Microwave theory and techniques Microwave ovens Heat transfer Permittivity Electromagnetics

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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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Shape-independent hardness estimation using deep learning and a GelSight tactile sensor

Shape-independent hardness estimation using deep learning an...

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IEEE International Conference on Robotics and Automation (ICRA)

作者： Wenzhen Yuan Chenzhuo Zhu Andrew Owens Mandayam A. Srinivasan Edward H. Adelson Department of Mechanical Engineering Computer Science and Artificial Intelligence Laboratory (CSAIL) Cambridge MA USA CSAIL MIT Cambridge MA USA Department of Electronical Engineering Tsinghua University Beijing China Electrical Engineering and Computer Science Department MIT Cambridge MA USA Computer Science Department UCL TouchLab London UK Department of Mechanical Engineering Research Laboratory of Electronics Cambridge MA USA Department of Brain and Cognitive Sciences and CSAIL MIT Cambridge MA USA

Hardness is among the most important attributes of an object that humans learn about through touch. However, approaches for robots to estimate hardness are limited, due to the lack of information provided by current tactile sensors. In this work, we address these limitations by introducing a novel method for hardness estimation, based on the GelSight tactile sensor, and the method does not require accurate control of contact conditions or the shape of objects. A GelSight has a soft contact interface, and provides high resolution tactile images of contact geometry, as well as contact force and slip conditions. In this paper, we try to use the sensor to measure hardness of objects with multiple shapes, under a loosely controlled contact condition. The contact is made manually or by a robot hand, while the force and trajectory are unknown and uneven. We analyze the data using a deep constitutional (and recurrent) neural network. Experiments show that the neural net model can estimate the hardness of objects with different shapes and hardness ranging from 8 to 87 in Shore 00 scale.

关键词： Force Tactile sensors Force measurement Shape Geometry

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