In this paper, we propose and analyze the terahertz (THz) bolometric vector detectors based on the graphene-channel field-effect transistors (GC-FET) with the black-P gate barrier layer or with the composite b-BN/blac...
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The terahertz (THz) band offers the advantages of mas-sive available bandwidth and small signal wavelengths with revolutionary potential in both communication and sensing applications. However, the increased noise pow...
The terahertz (THz) band offers the advantages of mas-sive available bandwidth and small signal wavelengths with revolutionary potential in both communication and sensing applications. However, the increased noise power from the larger bandwidth, as well as the increased path losses due to smaller wavelengths severely restrict the signal-to-noise ratio (SNR). In this light, reconfigurable intelligent surfaces (RISs) have been proposed as breakthrough devices that can be readily scaled up to create high-gain aperture systems, which are likely to have near-field applications. Here, wavefronts specifically engineered within the near field provide opportunities for improved sensing capabilities. Specifically, in this paper, we highlight how the greater depth of focus through Bessel beams can be utilized to improve the resolution capability of THz-band sensing. We numerically derive and show that Bessel beams can help improve target classification due to increased SNR in detection and increase resolution through increased bandwidth exploitation as well.
With increasing adoption of residential PV systems, net load forecasting is gradually shifting from forecasting pure load to forecasting pure load with PV generation. This paper explicitly compares two methods of net ...
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Communication-based devices are extensively used in the power grid, and studying the power and communication systems as a cyber-physical system before their deployment is essential. Co-simulation can be used for study...
Communication-based devices are extensively used in the power grid, and studying the power and communication systems as a cyber-physical system before their deployment is essential. Co-simulation can be used for studying power system stability, cyberattack detection and mitigation strategies, and controller performance. In co-simulation, both the power and communication layers are simulated simultaneously. Previous work has developed co-simulation platforms; however, it does not provide a comprehensive comparison of different co-simulation platforms. Furthermore, the slow simulation speed of co-simulation in some of the proposed platforms reduces the scalability capability dramatically. In this paper, five cyber-physical co-simulation platforms are implemented using PSCAD v5, and their merits and demerits are comprehensively evaluated.
In this work, a deep reinforcement learning (DRL)-based controller is presented to improve the performance of an existing control process in inverter-based resources (IBR). A DRL algorithm is utilized to learn a model...
In this work, a deep reinforcement learning (DRL)-based controller is presented to improve the performance of an existing control process in inverter-based resources (IBR). A DRL algorithm is utilized to learn a model-free value function which further improves the transient response of an IBR over fast response time frames. In addition, the developed controller provides black-box control, that is, it performs the desired control action without accessing or modifying the internal parameters of the existing controller in an IBR. The developed controller is tested in case studies utilizing EMT simulations in PSCAD/EMTDC and its performance, resilience, and adaptiveness are verified.
Modern machine learning problems, such as hyperparameter optimization, meta learning, and adversarial training, adopt a bilevel learning formulation. Such problems involve a nested relation between inner- and outer-le...
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Modern machine learning problems, such as hyperparameter optimization, meta learning, and adversarial training, adopt a bilevel learning formulation. Such problems involve a nested relation between inner- and outer-level problems, which often have suboptimal solutions with poor generalization ability. To address this issue, this paper proposes an ensemble method tailored to bilevel learning. Our method finds a nested ensemble of inner and outer parameters that improve generalization. We instantiate our general results with meta learning. We show theoretically and empirically that the diversity and the smoother loss landscape of the proposed ensemble methods lead to improved generalization over the state-of-the-art method.
Deep Reinforcement Learning (DRL) has achieved great success in solving complicated decision-making problems. Despite the successes, DRL is frequently criticized for many reasons, e.g., data inefficient, inflexible an...
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Utilizing power sharing controllers in a fully inverter-based power system (FIBPS) improves the system response to disturbances, despite the lack of mechanical inertia. However, a power sharing controller synchronizes...
Utilizing power sharing controllers in a fully inverter-based power system (FIBPS) improves the system response to disturbances, despite the lack of mechanical inertia. However, a power sharing controller synchronizes its internal clock with the global positioning system (GPS) to improve its timing accuracy. This may expose the power sharing controller to a GPS spoofing attack that disrupts its operation. This paper proposes a power sharing strategy for an FIBPS that is resilient to GPS spoofing attacks. The impact of a GPS spoofing attack on the employed grid-supporting power sharing controller is studied. Then, a state observer is designed to estimate the voltage angle of the grid-supporting inverter. Finally, a control loop is designed to mitigate GPS spoofing attack by correcting the voltage angle according to its estimated value. The performance of the proposed method is evaluated using time-domain simulation case studies on the IEEE 9-bus benchmark system in PSCAD/EMTDC software.
This paper presents a human-as-advisor architecture for shared human-machine autonomy in dynamic systems. In the human-as-advisor architecture, the human provides suggested control actions to the autonomous system; th...
This paper presents a human-as-advisor architecture for shared human-machine autonomy in dynamic systems. In the human-as-advisor architecture, the human provides suggested control actions to the autonomous system; the system uses a model of the human controller to ascertain the system’s state as perceived by the human. The system combines this information with additional sensor measurements, yielding an improved state estimate. We apply this architecture to the problem of lane-centering an autonomous vehicle in the presence of conflicting lane markings that render the true lane center uncertain. We model conflicting lane markings with a multi-component Gaussian mixture model. The human-suggested course of action is interpreted as an additional sensor measurement, which a Kalman filter is designed to combine with a speedometer and camera for improving the state estimate. With human input from our human-as-advisor architecture, the vehicle centers itself in the lane; without human input, the vehicle does not center itself. We also demonstrate the human-as-advisor architecture is robust to additive output matrix uncertainty and non-linear perturbations in the human model used to interpret the human-suggested control actions.
Single-stage 48V-to-1V regulated solutions for high-performance processors become increasingly popular. This paper presents a full-bridge transformer-based buck converter with the current-doubler rectifier. The transf...
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ISBN:
(数字)9798331516116
ISBN:
(纸本)9798331516123
Single-stage 48V-to-1V regulated solutions for high-performance processors become increasingly popular. This paper presents a full-bridge transformer-based buck converter with the current-doubler rectifier. The transformer adopts a half-turn winding structure for reduced resistance and leakage inductance. Operating principles of the converter with the half-turn transformer and the converter’s optimized printed circuit board layout are illustrated. Synchronous rectifiers are integrated in high-frequency loops and are treated carefully to reduce parasitic-inductor-induced loss. With the help of recent advances in gallium nitride (GaN) and silicon transistors, a 48V-to-1.8V GaN-based prototype switching at 700 kHz is constructed, which achieves 95.34% peak efficiency, 92.79% full-load efficiency (including gating loss) and 576 W/in 3 power density with 50-A current per phase. The same hardware achieves 94.00% peak efficiency and 89.75% full-load efficiency with 55-A current per phase in 48V-to-1.0V conversion. Experimental results with 54-V input are also included in this paper, demonstrating the great potential of the single-stage solution for future data centers.
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