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RIS-Assisted Communication Radar Coexistence: Joint Beamforming Design and Analysis
[article]
2022
arXiv
pre-print
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Integrated sensing and communication (ISAC) has been regarded as one of the most promising technologies for future wireless communications. However, the mutual interference in the communication radar coexistence system cannot be ignored. Inspired by the studies of reconfigurable intelligent surface (RIS), we propose a double-RIS-assisted coexistence system where two RISs are deployed for enhancing communication signals and suppressing mutual interference. We aim to jointly optimize the
arXiv:2201.07399v1
fatcat:rr4leioivzfctbgylxr4hqxzra
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... ng of RISs and radar to maximize communication performance while maintaining radar detection performance. The investigated problem is challenging, and thus we transform it into an equivalent but more tractable form by introducing auxiliary variables. Then, we propose a penalty dual decomposition (PDD)-based algorithm to solve the resultant problem. Moreover, we consider two special cases: the large radar transmit power scenario and the low radar transmit power scenario. For the former, we prove that the beamforming design is only determined by the communication channel and the corresponding optimal joint beamforming strategy can be obtained in closed-form. For the latter, we minimize the mutual interference via the block coordinate descent (BCD) method. By combining the solutions of these two cases, a low-complexity algorithm is also developed. Finally, simulation results show that both the PDD-based and low-complexity algorithms outperform benchmark algorithms.
An Improved Traffic Congestion Monitoring SystemBased on Federated Learning
2020
Information
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This study introduces a software-based traffic congestion monitoring system. The transportation system controls the traffic between cities all over the world. Traffic congestion happens not only in cities, but also on highways and other places. The current transportation system is not satisfactory in the area without monitoring. In order to improve the limitations of the current traffic system in obtaining road data and expand its visual range, the system uses remote sensing data as the data
doi:10.3390/info11070365
fatcat:t7nhlt47fjb2lj7hxs4e324vby
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... rce for judging congestion. Since some remote sensing data needs to be kept confidential, this is a problem to be solved to effectively protect the safety of remote sensing data during the deep learning training process. Compared with the general deep learning training method, this study provides a federated learning method to identify vehicle targets in remote sensing images to solve the problem of data privacy in the training process of remote sensing data. The experiment takes the remote sensing image data sets of Los Angeles Road and Washington Road as samples for training, and the training results can achieve an accuracy of about 85%, and the estimated processing time of each image can be as low as 0.047 s. In the final experimental results, the system can automatically identify the vehicle targets in the remote sensing images to achieve the purpose of detecting congestion.
A Novel Tunable Dual-band Left-Handed Metamaterial
2017
Journal of Magnetics
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In this paper, we propose a novel tunable left-handed metamaterial (LHM), the capacitor-loaded short wire pairs (CL-SWPs). It is composed of a pair of short wires connected through a variable capacitor. This LHM is single-sided, and it exhibits not only tunable negative permeability, but also a wide band negative permittivity. It is pointed out with theoretical analysis that its left-handed performance is related to the mutual coupling coefficient. A tunable dual-band LHM is also proposed by
doi:10.4283/jmag.2017.22.4.610
fatcat:ngjbz7aozvbhvnktcq4ojyat5q
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... ply adding a double slits split ring resonator to this LHM. The simulated results indicate that the closer the two LH bands are, the better performance the CL-SWP related left-handed band is, hence identifying our theoretical analysis. The proposed structure is geometrically simple, low-cost and easy for fabrication, and it can be used as a basic particle in the design of tunable multi-band LHMs.
Resource Allocation for Millimeter-Wave Train-Ground Communications in High-Speed Railway Scenarios
[article]
2021
arXiv
pre-print
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With the development of wireless communication, higher requirements arise for train-ground wireless communications in high-speed railway (HSR) scenarios. The millimeter-wave (mm-wave) frequency band with rich spectrum resources can provide users in HSR scenarios with high performance broadband multimedia services, while the full-duplex (FD) technology has become mature. In this paper, we study train-ground communication system performance in HSR scenarios with mobile relays (MRs) mounted on
arXiv:2104.13623v1
fatcat:riqnqjs2ijhp5gho4kry5qgtta
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... top of train and operating in the FD mode. We formulate a nonlinear programming problem to maximize network capacity by allocation of spectrum resources. Then, we develop a sequential quadratic programming (SQP) algorithm based on the Lagrange function to solve the bandwidth allocation optimization problem for track-side base station (BS) and MRs in this mm-wave train-ground communication system. Extensive simulation results demonstrate that the proposed SQP algorithm can effectively achieve high network capacity for trainground communication in HSR scenarios while being robust to the residual self-interference (SI).
An Intelligent Diagnosis Method for Machine Fault Based on Federated Learning
2021
Applied Sciences
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In engineering, the fault data unevenly distribute and difficultly share, which causes that the existing fault diagnosis methods cannot recognize the newly added fault types. An intelligent diagnosis method for machine fault is proposed based on federated learning. Firstly, the local fault diagnosis models diagnosing the existing fault data and the newly added fault data are established by deep convolutional neural network. Then, the weight parameters of local models are fused into global model
doi:10.3390/app112412117
fatcat:6fnssx2pd5hyjleftzgxt6pgtm
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... parameters by federated learning. Finally, the global model parameters are transmitted to each local model. Therefore, each local model update into a global shared model which can recognize the newly added fault types. The proposed method is verified by bearing data. Compared with the traditional model, which can only diagnose the existing fault data but cannot recognize newly added fault types, the federated fault diagnosis model fusing weight parameters can diagnose newly added faults without exchanging the data, and the accuracy is 100%. The proposed method provides an effective method to solve the poor sharing of fault data and poor generalization of fault diagnosis model for mechanical equipment.
Flexible pH sensor based on a conductive PANI membrane for pH monitoring
2020
RSC Advances
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A conductimetric flexible film pH sensor working in sensing materials of PANI membrane was developed for clinic wound monitoring.
doi:10.1039/c9ra09188b
pmid:35492551
pmcid:PMC9047031
fatcat:c2p5dxzxfjdndfogzspbrj7v4q
Moving Car Recognition and Removal for 3D Urban Modelling Using Oblique Images
2021
Remote Sensing
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With the progress of photogrammetry and computer vision technology, three-dimensional (3D) reconstruction using aerial oblique images has been widely applied in urban modelling and smart city applications. However, state-of-the-art image-based automatic 3D reconstruction methods cannot effectively handle the unavoidable geometric deformation and incorrect texture mapping problems caused by moving cars in a city. This paper proposes a method to address this situation and prevent the influence of
doi:10.3390/rs13173458
fatcat:lzzw27oiuzhk5ajtsjrp7dw5dm
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... moving cars on 3D modelling by recognizing moving cars and combining the recognition results with a photogrammetric 3D modelling procedure. Through car detection using a deep learning method and multiview geometry constraints, we can analyse the state of a car's movement and apply a proper preprocessing method to the geometrically model generation and texture mapping steps of 3D reconstruction pipelines. First, we apply the traditional Mask R-CNN object detection method to detect cars from oblique images. Then, a detected car and its corresponding image patch calculated by the geometry constraints in the other view images are used to identify the moving state of the car. Finally, the geometry and texture information corresponding to the moving car will be processed according to its moving state. Experiments on three different urban datasets demonstrate that the proposed method is effective in recognizing and removing moving cars and can repair the geometric deformation and error texture mapping problems caused by moving cars. In addition, the methods proposed in this paper can be applied to eliminate other moving objects in 3D modelling applications.
A Novel Tunable Triple-Band Left-Handed Metamaterial
2017
International Journal of Antennas and Propagation
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A novel tunable triple-band left-handed metamaterial (LHM) composed of a single-loop resonator (SLR) and a variable capacitor-loaded short wire pair (CL-SWP) printed on both sides of a substrate is presented in this paper. The CL-SWP-based metamaterial (MTM) is a novel single-sided LHM. It is theoretically analyzed capable of extracting tunable negative permeability and a wide-band negative permittivity. We ran simulations for the CL-SWP-based MTM, the SLR-based MTM, and the proposed LHM.
doi:10.1155/2017/7583736
fatcat:uw6lxqqq55enfdjrvl7wr3di6y
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... er with the measured results, it is identified that this novel LHM exhibits a tunable triple-band left-handed (LH) property. With the increase of the loaded capacitance, one LH band is relatively stable, while the other two are moving towards lower frequencies with their bandwidth getting wider and narrower, respectively. The surface current density distributions indicate that the first LH band is mainly decided by the SLR, one of the rest 2 LH bands is mainly decided by the CL-SWP, and the other one is decided by the SLR and CL-SWP together.
A Novel Dual-Band Left-Handed Metamaterial Design Method
2017
International Journal of Antennas and Propagation
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A novel dual-band left-handed metamaterial (LHM) design method is proposed in this paper. Unlike other methods, where the designers focused their attentions on designing single LHM unit with multiple electric/magnetic resonances or combining multiple different LHM units together, the proposed method in this paper introduces an additional magnetic resonance to extract negative permeability, taking advantage of the areas between neighboring units. In this paper, we first designed a single-band
doi:10.1155/2017/8920409
fatcat:h7d4fdoq75e6hfs6mc5vtlpmua
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... gle negative metamaterial (μ<0) and then connected neighboring units with metallic wires. This connection introduces a magnetic resonance that extracts another frequency band with negative permeability. With the help of arrayed metallic wires printed on the other side of the substrate, we successfully get a dual-band LHM. The proposed structures are analyzed with equivalent circuits and verified with simulations.
Study on the Water in Lignite by DSC
2017
MATEC Web of Conferences
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As pointed out in several previous works, new drying technologies must be developed to ensure lignite remained competitive. In order to design and test them, it was needed to have a better understanding of the characters of water in lignite. Using differential scanning calorimetry (DSC), three types of the water storing in the lignite were determined from congelation character. The contents of the free water and bound water were experimentally measured from their heats of congelation,
doi:10.1051/matecconf/201710002005
fatcat:jppa6dfdazf75jkyc4bdjx4pna
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... ly. The results shows that the congelation temperature and the freezing heat per weight unit of the bound water vary in different types of lignite. It is deduced that the bound water in lignite can reflect the character of lignite. Besides, the total water content of free water and bound water is less than that measured by fully drying at 105 o C. Therefore, it is deduced that there is a kind of water not frozen in the lignite, possibly because its molecular cluster is too small.
Computer-generated hologram of asymmetry fractional Fourier transform
2005
Holography, Diffractive Optics, and Applications II
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A new optical encryption technique based on computer-generated hologram (CGH) and fractional Fourier transform (FRT) is presented. And the algorithm of making asymmetry FRT CGH is provided in this paper. In this method, the fractional Fourier transform of the input image is performed by two one-dimensional FRT with different orders in the x and y directions in cascade. With Lohmann Ⅲ detour phase encoding method and computer plotting program, the transformed image is encoded and fabricated into
doi:10.1117/12.574531
fatcat:2teeowqkybanpgamw6rhhlyghu
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... CGH on the computer. Then a piece of asymmetry fractional Fourier transform CGH (AFRTCGH) of original input image is obtained. In order to reconstruct the encoded image, a special fractional Fourier transform systems with two special cylinder lens' are needed. Namely, only when the transform order in each direction is respectively matched with that of the asymmetry fractional Fourier transform CGH, can the encoded image be reconstructed exactly. Because of its particularity of image reconstruction, it is regarded as a new optical security system and can be used in anti-counterfeiting. When it is used to encrypt image or to anti-Counterfeit, anticounterfeiting intensity can be improved greatly. So it has very high applying value.
A Two-Step Method for Ionospheric Clutter Mitigation for HFSWR with Two-Dimensional Dual-Polarized Received Array
2020
IEEE Access
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For high-frequency surface wave radar (HFSWR), the unwanted radio wave originated from the ionosphere is commonly called ionospheric clutter. Its presence seriously affects the performance of the HFSWR and extremely degrades the radar capability to detect target over long distances. To solve this problem, this paper proposes a two-step method for ionospheric clutter mitigation with two-dimensional dual-polarized received array. The proposed method first performs parameter estimation of the
doi:10.1109/access.2020.2999463
fatcat:bb5jidhafzfqvftekizqlirs5q
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... er, and then gives a polarimetric-adaptive-based oblique projection filter (PAB-OPF) to suppress the clutter. In the first step, due to the fact that vertically and horizontally polarized antennas are at different array elements for reducing mutual coupling and hardware cost, 2-D DOAs are estimated to give phase compensation for polarization phase delay estimation. In the second step, the PAB-OPF is proposed to eliminate phase inconsistency by matching different polarization phase delays for different vertically polarized antennas, and then to suppress the clutter efficiently in space-polarization domain. Error analysis and computational complexity of the proposed method are derived. Experimental results are shown to illustrate the superiority of the proposed method for ionospheric clutter suppression. INDEX TERMS High-frequency surface wave radar, dual-polarized array, ionospheric clutter, oblique projection, clutter mitigation.
Stemming Downlink Leakage from Training Sequences in Multi-User MIMO Networks
2016
Proceedings of the 2016 ACM SIGSAC Conference on Computer and Communications Security - CCS'16
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Multi-User MIMO has attracted much attention due to its significant advantage of increasing the utilization ratio of wireless channels. Recently a serious eavesdropping attack, which exploits the CSI feedback of the FDD system, is discovered in MU-MIMO networks. In this paper, we firstly show a similar eavesdropping attack for the TDD system is also possible by proposing a novel, feasible attack approach. Following it, a malicious user can eavesdrop on other users' downloads by transforming
doi:10.1145/2976749.2978412
dblp:conf/ccs/MaoZZ16
fatcat:qt5shmty4vfhhisvcyfnkfeifu
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... ning sequences. To prevent this attack, we propose a secure CSI estimation scheme for instantaneous CSI. Furthermore, we extend this scheme to achieve adaptive security when CSI is relatively statistical. We have implemented our scheme for both uplink and downlink of MU-MIMO and performed a series of experiments. Results show that our secure CSI estimation scheme is highly effective in preventing downlink leakage against malicious users.
Study on Thermal Conversion of the Waste Oil Absorbin Activated Carbon
2017
MATEC Web of Conferences
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The pyrolysis and combustion characteristics of a waste oil absorbing activated carbon were investigated using a thermogravimetric analyzer under heating rate of 10 o C/min from 25 o C to 1000 o C. The activated carbon sample was used to adsorb waste oil. The results obtained, indicates that DTG curves of the pyrolysis process of the sample has three peaks at 106 o C, 190 o C and 249 o C. The four peaks are observed in the DTG curves of the incineration process. The first peak at 110 o C is
doi:10.1051/matecconf/201710004003
fatcat:zprussfp5vfklltqxlwvrn6laq
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... ed by water emission. The second peak corresponds to the temperature of 190 o C that is consistent with the second peak temperature of the pyrolysis process of the sample. The third peak at 240 o C which is 9 o C lower than the third peak temperature of the pyrolysis process. The second and third peaks maybe caused by the emission of the waste oil absorbed in the activated carbon. The fourth peak temperature is 516 o C and the weight loss within the range of 400 o C ~ 560 o C is more obvious. The weight loss is caused by the residue char combustion.
Toward Wireless Security without Computational Assumptions—Oblivious Transfer Based on Wireless Channel Characteristics
2014
IEEE transactions on computers
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Wireless security has been an active research area since the last decade. A lot of studies of wireless security use cryptographic tools, but traditional cryptographic tools are normally based on computational assumptions, which may turn out to be invalid in the future. Consequently, it is very desirable to build cryptographic tools that do not rely on computational assumptions. In this paper, we focus on a crucial cryptographic tool, namely 1-out-of-2 oblivious transfer. This tool plays a
doi:10.1109/tc.2013.27
fatcat:iukoijnhh5hfbetlxyfnfjwzhy
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... l role in cryptography because we can build a cryptographic protocol for any polynomial-time computable function using this tool. We present a novel 1-out-of-2 oblivious transfer protocol based on wireless channel characteristics, which does not rely on any computational assumption. We also illustrate the potential broad applications of this protocol by giving two applications, one on private communications and another on privacy preserving password verification. We have fully implemented this protocol on wireless devices and conducted experiments in real environments to evaluate the protocol and its application to private communications. Our experimental results demonstrate that it has reasonable efficiency.
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