This paper develops a novel method for reconstructing the full-field response of structural dynamic systems using sparse measurements. The singular value decomposition is applied to a frequency response matrix relatin...
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This paper develops a novel method for reconstructing the full-field response of structural dynamic systems using sparse measurements. The singular value decomposition is applied to a frequency response matrix relating the structural response to physical loads, base motion, or modal loads. The left singular vectors form a non-physical reduced basis that can be used for response reconstruction with far fewer sensors than existing methods. The contributions of the singular vectors to measured response are termed singular-vector loads (SVLs) and are used in a regularized Bayesian framework to generate full-field response estimates and confidence intervals. The reconstruction framework is applicable to the estimation of single data records and power spectral densities from multiple records. Reconstruction is successfully performed in configurations where the number of SVLs to identify is less than, equal to, and greater than the number of sensors used for reconstruction. In a simulation featuring a seismically excited shear structure, SVL reconstruction significantly outperforms modal FRFbased reconstruction and successfully estimates full-field responses with as few as two uniaxial accelerometers. SVL reconstruction is further verified in a simulation featuring an acoustically excited cylinder. Finally, response reconstruction and uncertainty quantification are performed on an experimental structure with three shaker inputs and 27 triaxial accelerometer outputs.
This study introduces a quad-port multi-input multi-output antenna design specifically suited for fifth-generation wireless technology. The antenna geometry is characterized by a flower-shaped configuration, featuring...
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This study introduces a quad-port multi-input multi-output antenna design specifically suited for fifth-generation wireless technology. The antenna geometry is characterized by a flower-shaped configuration, featuring five petals complemented by a circular slot, positioned in the ground plane to improve operational bandwidth. The effective realization of wide-band characteristics has been studied utilizing the analysis of characteristic modes. The design antenna demonstrates simulated performance parameters that cover the millimeter-wave frequency band from 25.6 to 32.4 GHz, delivering a maximum gain of 6.1 dBi and ensuring minimum port isolation of > 15 dB across all ports. In addition, a circular stub is purposefully positioned over the slot to facilitate circular polarization radiation behavior at 26.3 GHz, exhibiting an axial ratio bandwidth of 0.5 GHz (26-26.5 GHz). Further, the proposed antenna design is subjected to validation encompassing diversity metrics. The proposed antenna structure is successfully fabricated, and its performance is experimentally validated. A comprehensive comparative analysis is then conducted to evaluate its alignment with the simulated results.
This paper investigates a multi-antenna, multi-input multi-output (MIMO) dual-functional radar and communication (DFRC) system platform. The system simultaneously detects radar targets and communicates with downlink c...
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This paper investigates a multi-antenna, multi-input multi-output (MIMO) dual-functional radar and communication (DFRC) system platform. The system simultaneously detects radar targets and communicates with downlink cellular users. However, the modulated information within the transmitted waveforms may be susceptible to eavesdropping. To ensure the security of information transmission, we introduce non-orthogonal multiple access (NOMA) technology to enhance the security performance of the MIMO-DFRC platform. Initially, we consider a scenario where the channel state information (CSI) of the radar target (eavesdropper) is perfectly known. Using fractional programming (FP) and semidefinite relaxation (SDR) techniques, we maximize the system's total secrecy rate under the requirements for radar detection performance, communication rate, and system energy, thereby ensuring the security of the system. In the case where the CSI of the radar target (eavesdropper) is unavailable, we propose a robust secure beamforming optimization model. The channel model is represented as a bounded uncertainty set, and by jointly applying first-order Taylor expansion and the S-procedure, we transform the original problem into a tractable one characterized by linear matrix inequalities (LMIs). Numerical results validate the effectiveness and robustness of the proposed approach.
Short-packet communication (SPC) in multi-input multi-output (MIMO) networks with energy scavenging (ES) harnesses modern techniques such as MIMO processing, SPC, and radio frequency ES to achieve optimal spectrum usa...
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Short-packet communication (SPC) in multi-input multi-output (MIMO) networks with energy scavenging (ES) harnesses modern techniques such as MIMO processing, SPC, and radio frequency ES to achieve optimal spectrum usage, high reliability, low latency, and high energy efficiency . Nevertheless, a comprehensive performance analysis of SPC in MIMO system with ES under practical circumstances-successive interference cancellation imperfection (SICi), channel state information imperfection (CSIi), and nonlinear ES (nlES)-has yet to be conducted, particularly for advanced and conventional multiple access (MA) schemes-nonorthogonal MA (NOMA) and orthogonal MA (OMA). This paper addresses this gap by proposing an analytical framework, validated through Monte Carlo simulations, which quickly evaluates the total throughput and average block-error rate of SPC in MIMO system with nlES in key parameters such as transmit power, SICi level, CSIi level, power splitting factor, time division factor, power saturation threshold, antenna configuration, energy conversion efficiency. The results reveal that, contrary to long-packet communication, NOMA performs worse than OMA in SPC in MIMO system with nlES.
In this paper,a hybrid integrated broadband Doherty power amplifier(DPA)based on a multi-chip module(MCM),whose active devices are fabricated using the gallium nitride(GaN)process and whose passive circuits are fabric...
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In this paper,a hybrid integrated broadband Doherty power amplifier(DPA)based on a multi-chip module(MCM),whose active devices are fabricated using the gallium nitride(GaN)process and whose passive circuits are fabricated using the gallium arsenide(GaAs)integrated passive device(IPD)process,is proposed for 5G massive multiple-inputmultiple-output(MIMO)*** inverted DPA structure with a low-Q output network is proposed to achieve better bandwidth performance,and a single-driver architecture is adopted for a chip with high gain and small *** proposed DPA has a bandwidth of 4.4-5.0 GHz that can achieve a saturation of more than 45.0 *** gain compression from 37 dBm to saturation power is less than 4 dB,and the average power-added efficiency(PAE)is 36.3%with an 8.5 dB peak-to-average power ratio(PAPR)in 4.5-5.0 *** measured adjacent channel power ratio(ACPR)is better than50 dBc after digital predistortion(DPD),exhibiting satisfactory linearity.
Control of input-affine nonlinear dynamical systems is investigated in this paper. In this regard, a system of linear inequalities (SLI) in the control inputs is developed, and it is proved that if this SLI has a solu...
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Control of input-affine nonlinear dynamical systems is investigated in this paper. In this regard, a system of linear inequalities (SLI) in the control inputs is developed, and it is proved that if this SLI has a solution at all times, applying it to the system leads to moving its state trajectories towards the desired point in space for all initial conditions. But, since it may happen that this SLI has infinitely many solutions or even no solution, the best (possibly, approximate) solution is obtained by solving a linear programming (LP) problem. Different LP problems with different properties and applications are proposed for this purpose. Formulation of the control problem as an LP makes it possible to take into account the effect of actuator saturation simply by adding bound constraints to the problem. We can also make the resulting control system robust to model uncertainties. Some numerical examples including the output voltage regulation of double-source DC-DC converter and robot path-planning, both by considering the effect of actuators saturation and taking into account the uncertainties in model, are also presented. (c) 2021 European Control Association. Published by Elsevier Ltd. All rights reserved.
In this paper, we address the problem of frequency offset and channel gain estimation for frequency-selective multi-input multi-output (MIMO) correlated fading channels. A maximum-likelihood (ML) frequency offset (FO)...
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In this paper, we address the problem of frequency offset and channel gain estimation for frequency-selective multi-input multi-output (MIMO) correlated fading channels. A maximum-likelihood (ML) frequency offset (FO) estimator is proposed by using the Bayesian approach. We show that the proposed FO estimator is efficient and asymptotically optimal. Based on the FO estimate, we derive the linear minimum mean square error (LMMSE) channel estimator and analytically investigate the effect of frequency offset estimation error on the mean square error (MSE) performance of the channel estimator. Finally, the performances of the FO and channel estimation are evaluated by simulation results.
As an integral part of a plantwide control system for large-scale nonlinear systems with non-measurable states and time-delay in measured outputs, a multi-input multi-output (MIMO) adaptive neural network predictive c...
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As an integral part of a plantwide control system for large-scale nonlinear systems with non-measurable states and time-delay in measured outputs, a multi-input multi-output (MIMO) adaptive neural network predictive controller (ANNPC) is presented. A neural network model-based observer is used in the structure of the proposed controller to estimate the unknown states. Then, an adaptive predictor is designed based on the observer and is employed to predict non-measurable states. Stability of the proposed observer and controller is proved using Lyapunov function theorem. The proposed controller is used as a part of the control system of a Vinyl Acetate monomer (VAM) process. A new partially centralized structure is developed for plantwide control of the process and the efficiency of the proposed controller particularly in diminishing the effect of measurement time-delay is shown, in-silico, by numerical simulation of a VAM plant under control. The obtained results are compared with the results of the conventional PI-based control system of VAM process. (C) 2018 Elsevier Ltd. All rights reserved.
Model uncertainty is an inseparable part of a methane reforming process since many of its main parameters describe microscale behavior. A robust control approach for a catalytic fuel reformer is presented to guarantee...
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Model uncertainty is an inseparable part of a methane reforming process since many of its main parameters describe microscale behavior. A robust control approach for a catalytic fuel reformer is presented to guarantee performance constraints are met even in the presence of model uncertainty. The control strategy is based on a recently developed sampling-based robust model predictive control (RMPC) with a new approach to capturing the uncertainty. Particular features of the control strategy is the use of a metric for coking susceptibility as a constraint on the inlet gas composition, a cost based metric for evaluating decisions on controller commands, and the ability to meet constraints on reactor temperature, outlet gas energy content, and hydrogen to carbon monoxide ratio. Simulation results carried out in MATLAB on random plants show the constraints are met regardless the model uncertainty and measurement noise.
An ultra-wideband (UWB) slot antenna for diversity applications is introduced. The overall structure of the antenna consists of two similar coplanar waveguide (CPW)-fed stepped rectangular slots placed in an orthogona...
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An ultra-wideband (UWB) slot antenna for diversity applications is introduced. The overall structure of the antenna consists of two similar coplanar waveguide (CPW)-fed stepped rectangular slots placed in an orthogonal position. The slots are asymmetric with respect to their placement in the ground plane. The CPW feeds are double stepped and terminated on hexagonal patches for better impedance matching. A wide impedance bandwidth (measured) from 3 to 12 GHz with an isolation better than 15 dB is obtained with this antenna. To improve the isolation, the design is modified and an I-shaped slot strip is introduced between the two slot antennas. With this, the isolation is brought about 25 dB of most of the band, while the impedance bandwidth remains the same (2.8-12 GHz for port 1, measured and 2.9-12 GHz for port 2, measured). The far-field radiation patterns are also measured and a peak gain of about 5 dBi is obtained. Finally, the diversity parameters such as envelope correlation coefficient and capacity loss are calculated and found to have low values. The antenna is expected to be useful for UWB diversity applications with good isolation.
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