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Optimizing etching process recipe based on Kernel Ridge Regression

JOURNAL OF MANUFACTURING PROCESSES 2021年 61卷 454-460页

作者： Chen, Heping Leclair, John Texas State Univ San Marcos TX 78666 USA Samsung Austin TX 78666 USA

Exploring optimal recipes to reduce dimensional variations is critical in etching processes. Variations in critical dimensions that were acceptable previously can become problematic because of smaller node sizes and more complex structures. Dry etch can be a major source of variations and will be the focus of this research. Advanced Process Control (APC) has been widely studied in semiconductor manufacturing. Even though different APC methods have been developed to adjust recipes, it is challenging to explore an optimal recipe to achieve multiple critical dimensions. In this paper, a learning method based on Kernel Ridge Regression (KRR) is proposed to generate optimal recipes for multi-input multi-output (MIMO) systems. A KRR parameter optimization method is developed. To improve the recipe optimization process, a feedback fine tuning method is proposed. Experimental data in a dry etch process were collected and processed for model construction and recipe optimization. The results demonstrate the effectiveness of the proposed method in exploring optimal recipes for MIMO systems.

关键词： Kernel Ridge Regression Etching process Advanced process control multi-input multi-output

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Nonlinear Adaptive Disturbance Rejection Control Strategy Based on VSG for Photovoltaic-Storage Grid-Connected Inverter

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IEEE ACCESS 2023年 11卷 139534-139545页

作者： Kong, Fannie Zhang, Haochen Wu, Zhuolin Guo, Zhuangzhi Guangxi Univ Sch Elect Engn Nanning 530005 Peoples R China Henan Univ Engn Sch Elect Informat Engn Zhengzhou 450051 Peoples R China

In this paper, a nonlinear adaptive disturbance rejection control (NADRC) strategy is designed to overcome the limitations of the traditional virtual synchronous generator (VSG) control method in photovoltaic (PV) grid-connected energy storage systems. This strategy utilizes exact feedback linearization and linear optimal control theory to establish a nonlinear adaptive disturbance rejection control law based on the virtual synchronous generator. It achieves zero static error control and noise adaptive stabilization of the AC link in a multiple-input multiple-output system. Compared with the simulation results of the grid-connected inverter voltage and current double closed-loop (VACDCL) strategy, the nonlinear adaptive disturbance rejection control effectively mitigates the fluctuations in load current caused by the photovoltaic energy storage module. It ensures power tracking under variable power conditions and outperforms traditional PI dual-loop control in terms of dynamic and static regulation performance as well as grid-connected current quality. Furthermore, this strategy's anti-disturbance adaptive link can quickly respond to system disturbances like frequency drift, voltage oscillations, and load current variations, thereby improving system performance.

关键词： INDEX TERMS Adaptive exact feedback linearization grid-connected inverter multi-input multi-output nonlinear adaptive disturbance rejection control virtual synchronous generator voltage and current dual closed-loop strategy

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Adaptive actuator failure compensation for a class of MIMO nonlinear time delay systems

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NONLINEAR DYNAMICS 2015年第2期79卷 865-883页

作者： Hashemi, Mahnaz Askari, Javad Ghaisari, Jafar Isfahan Univ Technol Dept Elect & Comp Engn Esfahan *** Iran

In this paper, an adaptive actuator failure compensation scheme is proposed for a class of parametric-strict-feedback multi- input multi-output nonlinear systems with unknown time- varying state delays. The considered actuator failures are types of loss of effectiveness, in which unknown system inputs may lose unknown fraction of their effectiveness. The adaptive compensation controller is constructed by utilizing a backstepping design method. The appropriate Lyapunov-Krasovskii functionals are introduced to design new adaptive laws to compensate the unknown actuator failures as well as uncertainties from unknown parameters and state delays. The boundedness of all the closed-loop signals is guaranteed, and the tracking errors are proved to converge to a small neighborhood of the origin. Simulation results are provided to show the effectiveness of the proposed approach.

关键词： Actuator failure multi-input multi-output Nonlinear systems Time-varying state delay Adaptive compensation Backstepping

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Data-Aided Spatial Modulation

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IEEE ACCESS 2017年 5卷 7285-7293页

作者： Sha, Ziyuan Zhu, Xudong Zhao, Peiyao Wang, Zhaocheng Tsinghua Univ Dept Elect Engn Tsinghua Natl Lab Informat Sci & Technol Beijing 100084 Peoples R China

Spatial modulation utilizes the diversity of multiple-input multiple-output channel to improve the spectral efficiency. In time-variant wireless channels, its performance degrades due to the inaccuracy of channel estimation (CE). In this paper, a data-aided channel tracking (DACT) method is proposed to improve its CE accuracy in time-variant wireless channels. Specifically, the demodulated data at current time slot are used to update the subsequent channel state information. Two different DACT methods with different pilot insertion patterns are proposed: 1) feedback DACT (FDACT) where when a symbol error is detected, the receiver will inform the transmitter to insert pilots and estimate the channel again;2) periodical DACT (PDACT) where pilots are inserted periodically. Theoretical analysis of the CE error in time-variant channels is presented, which indicates that the CE accuracy could be significantly improved in comparison to the conventional counterpart. Moreover, the closed-form expressions of bit error rate for FDACT and frame error rate for PDACT are derived. Simulations are conducted to verify the efficiency of the proposed DACT methodologies.

关键词： multi-input multi-output spatial modulation data-aided channel tracking channel estimation time-variant channel

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Compact Sub-6 GHz and mmWave 5G Wideband 2 x 1 MIMO Antenna with High Isolation Using Parasitically Placed Double Negative (DNG) Isolator

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WIRELESS PERSONAL COMMUNICATIONS 2022年第3期122卷 2839-2857页

作者： Sharma, Rashbha Khanna, Rajesh Geetanjali Thapar Inst Engn & Technol Deemed Univ Dept Elect & Commun Engn 32 Bhadson Rd Patiala Punjab India Chitkara Univ Inst Engn & Technol Rajpura Punjab India

In this paper a multiband modified 'W' shaped, multiple input multiple output (MIMO) antenna with a metamaterial inspired isolator for enhanced isolation is proposed for 5G application. The two-element MIMO antenna comprises of a closely placed (edge to edge gap of 0.117 lambda(o), lambda(o) = highest operating wavelength) antenna elements that covers both sub-6 GHz (3.42-4.25 GHz) and millimeter wave (mmWave) range bands (24.8-26.5 GHz) of 5G with bandwidth of 821 MHz and 1630 MHz. The MIMO antenna also covers bands C (7.44-7.92 GHz), X (9.9-10.49 GHz), Ku (12.02-13.39 GHz & 15.92-17.492 GHz), K (19.49-22.42 GHz), partially. The isolation level in all resonating bands remain near to the acceptable value of (|S-12|> -15 dB) however a very significant mutual coupling effect is observed in sub-6 GHz range (|S-12|= -11.92 dB at 3.94 GHz). To improve the isolation in sub-6 GHz band, a metamaterial inspired isolator comprising of Double negative (DNG) unit cells is uniquely placed along the side of the closely positioned antenna elements. Simulated results indicate that isolation level improves to (|S-12|= -16.1 dB at 3.94 GHz) after placing the DNG metamaterial based isolator. The antenna performance parameters such as gain, return loss, bandwidth, Envelope correlation coefficient (ECC), Diversity gain (DG) and radiation efficiency are not affected by placement of isolator. The metamaterial equipped MIMO antenna (Meta-MIMO antenna) has a compact structure of 70 x 40 x 0.8 mm(3), with a high isolation in all bands (|S-12|> -16 dB), peak gain of 7.8dBi, low ECC (< 0.05), high diversity gain (9.98 dB) and efficiency (approximate to 91.38%). Further the proposed Meta-MIMO antenna performance for practical applications is investigated by connecting to different sizes of ground plane, the results indicate that the isolation levels and efficiency do not deteriorate.

关键词： 5G multi-input multi-output Millimeter wave Sub-6 GHz Metamaterials Isolation

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Dynamic modeling, simulation, and MIMO predictive control of a tubular solid oxide fuel cell

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JOURNAL OF PROCESS CONTROL 2012年第8期22卷 1502-1520页

作者： Spivey, Benjamin J. Edgar, Thomas F. Univ Texas Austin Dept Chem Engn Austin TX 78712 USA

Solid oxide fuel cells are a promising option for distributed energy stationary power generation that offers efficiencies up to 50% in stand-alone applications, 70% in hybrid gas turbine applications and 80% in cogeneration. To advance SOFC technology sufficiently for widespread market penetration, the SOFC must demonstrate improved cell lifetime from the status quo. Much research has been performed to improve SOFC lifetime using advanced geometries and materials, and in this research, we suggest further improving lifetime by designing an advanced control algorithm based upon preexisting mechanical stress analysis [1]. Control algorithms commonly address SOFC lifetime related operability objectives using unconstrained, SISO control algorithms that seek to minimize thermal transients. While thermal fatigue may be one thermal stress driver, these studies often do not consider maximum radial thermal gradients or critical absolute temperatures in the SOFC. In addition, researchers often discuss hot-spots as a critical lifetime reliability issue, but as previous stress work demonstrates, the minimum cell temperature is the primary thermal stress driver in tubular SOFCs modeled after the Siemens Power Generation, Inc. design. In this work, we present a dynamic, quasi-two-dimensional model for a high-temperature tubular SOFC combined with ejector and prereformer models. The model captures dynamics of critical thermal stress drivers and is used as the physical plant for closed-loop simulations with a constrained, MIMO model predictive control algorithm. Closed-loop simulation results demonstrate effective load-following, operability constraint satisfaction, and disturbance rejection. (C) 2012 Elsevier Ltd. All rights reserved.

关键词： multi-input multi-output Model predictive control Distributed parameter models Solid oxide fuel cell Dynamic simulation Nonlinear programming

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Particle swarm optimization assisted B-spline neural network based predistorter design to enable transmit precoding for nonlinear MIMO downlink

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NEUROCOMPUTING 2021年 458卷 336-348页

作者： Chen, Sheng Ng, Soon Xin Khalaf, Emad Morfeq, Ali Alotaibi, Naif Univ Southampton Sch Elect & Comp Sci Southampton SO17 1BJ Hants England King Abdulaziz Univ Elect & Comp Engn Dept Fac Engn Jeddah 21589 Saudi Arabia

For the multiple-input multiple-output (MIMO) downlink employing high-order quadrature amplitude modulation signaling and with nonlinear high power amplifiers (HPAs) at base station transmitter, the existing precoding designs relying on the linear MIMO channel can no longer work. We propose an effi-cient and accurate predistorter design to enable transmit precoding for nonlinear MIMO downlink. Specifically, we obtain the closed-form least squares estimates of the nonlinear HPA's amplitude and phase response using two B-spline neural networks during training. The estimated HPA's phase response automatically yields the estimate of the predistorter's phase response. Based on the B-spline neural net-work estimate of the HPA's amplitude response, we construct a B-spline neural network model for the predistorter amplitude response, and we adopt a particle swarm optimization (PSO) algorithm to solve this highly nonlinear optimization problem. Using our accurate predistorter estimate to pre-compensate for the nonlinear distortions of the transmit HPAs, a standard full-digital transmit precoding design can readily be adopted to combat the MIMO channel interference. A simulation study is conducted to demonstrate the effectiveness of our proposed PSO assisted predistorter design. (c) 2021 Elsevier B.V. All rights reserved.

关键词： Particle swarm optimization B-spline neural network Nonlinear inversion Nonlinear high power amplifier Predistorter multi-input multi-output Downlink precoding

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Energy optimization for full-duplex wireless-powered IoT networks using rotary-wing UAV with multiple antennas

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COMPUTER COMMUNICATIONS 2024年 215卷 62-73页

作者： Fathollahi, Leyla Feghhi, Mahmood Mohassel Atashbar, Mahmoud Univ Tabriz Fac Elect & Comp Engn Tabriz Iran Azarbaijan Shahid Madani Univ Dept Elect Engn Tabriz Iran

In this paper, we propose a novel design for the rotary-wing unmanned aerial vehicle (UAV)-enabled full-duplex (FD) wireless-powered Internet of Things (IoT) networks. In this network, the UAV is equipped with an antenna array, and the K IoT sensors, which are distributed randomly, use single-antenna to communicate. By sending the energy, the UAV as a hybrid access point, charges the sensors and collects information from them. Then, to manage the time and optimize the energy, the sensors are divided into N groups, so that the UAV equipped with multi-input multi-output (MIMO) technology can serve the sensors in a group, during the total time T. We provide a simple implementation of the wireless power transfer protocol in the sensors by using the time division multiple access (TDMA) scheme to receive information from the users. In other words, the sensors of each group receive energy from the UAV, when it hovers over the sensors of the previous group, and also when the UAV flies over the previous group to the current group. The sensors of each group send their information to the UAV, when the UAV is hovering over their group. Under these assumptions, we formulate two optimization problems: a sum throughput maximization problem, and a total time minimization problem. Numerical results show that our proposed optimal network provides better performance than the existing networks. In fact, our novel design can serve more sensors at the cost of using more antennas compared to that of the conventional networks.

关键词： Internet of things Unmanned aerial vehicle multi-input multi-output Wireless power transfer protocol Convex optimization

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Swept-sine integration method for complex amplitude extraction of swept-sine signal

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JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY 2020年第12期34卷 4981-4988页

作者： Zheng, Wei Cui, Xuli Chen, Huaihai Zheng, Ronghui Nanjing Univ Aeronaut & Astronaut State Key Lab Mech & Control Mech Struct Nanjing Jiangsu Peoples R China BSH Elect Appliances Co Ltd Jiangsu Nanjing Jiangsu Peoples R China

Swept-sine vibration test plays a significant role in product validations. As its basic step, the accuracy and efficiency of complex amplitude (which includes the amplitude and phase information of swept-sine signal) extraction have an important impact on the performance of swept-sine vibration test. In order to improve the efficiency while ensuring its accuracy, a swept-sine integration method is proposed. The proposed swept-sine integration method, which is inspired by tracking filter method and tracking integration method, utilizes a weighted integral process to extract the complex amplitude. A numeral example is presented to compare the performance of the proposed method with several other methods for complex amplitude extraction which are also reviewed in this paper. By comparing the results of the numerical example, some light is shed on the strength of the method proposed. Afterwards, the swept-sine integration method is applied in a real test, further validating the appliance value of this method.

关键词： Complex amplitude extraction Hilbert transform multi-input multi-output Swept-sine vibration Tracking filter

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Hierarchical BEM Based Channel Estimation With Very Low Pilot Overhead for High Mobility MIMO-OFDM Systems

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2022年第10期71卷 10543-10558页

作者： Zhang, Yanfeng Zhu, Xu Liu, Yujie Jiang, Yufei Guan, Yong Liang Lau, Vincent K. N. Harbin Inst Technol Sch Elect & Informat Engn Shenzhen Peoples R China Nanyang Technol Univ Continental NTU Corp Lab Singapore 639798 Singapore Hong Kong Univ Sci & Technol Dept Elect & Comp Engn Hong Kong Peoples R China

Channel estimation for multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems is a challenging issue in high mobility scenarios due to prohibitive pilot overhead and complexity. In this paper, a hierarchical basis expansion model (BEM) based channel estimation scheme is proposed for doubly selective channels, which requires a low pilot overhead and computational complexity. A mixed-BEM is proposed for time-varying channels alongside a complex exponential-BEM (CE-BEM), resulting in very few unknown parameters required for channel estimation. Based on the hierarchical BEM structure, an analytical channel estimation model is derived. By employing the block-structured sparsity and a small number of mixed-BEM coefficients in the antenna-time-BEM domain, a low-complexity estimator is proposed to recover the mixed-BEM coefficients accurately. The lower bound on the mean square error (MSE) of channel estimation is derived to verify the effectiveness of the proposed scheme. Simulation results show that the proposed channel estimation scheme significantly outperforms the existing methods in terms of MSE of channel estimation and bit error rate, with much lower pilot overhead and computational complexity.

关键词： Channel estimation Symbols OFDM Estimation Doppler effect Computational modeling Time-domain analysis Channel estimation basis expansion model multi-input multi-output orthogonal frequency division multiplexing sparse recovery

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