The emergence of electric Vertical Takeoff and Landing (eVTOL) aircraft makes cheap, quiet and reliable short-range flights possible. As a manned aircraft, eVTOL's occupant protection capability is critical and it...
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The stomatopod (mantis shrimp) visual system has recently provided a blueprint for the design of paradigm-shifting polarization and multispectral imaging sensors, enabling solutions to challenging medical and remote s...
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The experimental studies presented in this paper reveal that existing thermal management systems (TMS) and temperature-informed charging algorithms exhibit a response time lag of at least 5.3 minutes due to their reli...
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ISBN:
(数字)9798350376067
ISBN:
(纸本)9798350376074
The experimental studies presented in this paper reveal that existing thermal management systems (TMS) and temperature-informed charging algorithms exhibit a response time lag of at least 5.3 minutes due to their reliance on surface temperature measurements. The results indicate that changes in the internal thermal state of lithium-ion batteries (LIBs), induced by variations in charging currents, take an average of 2 minutes to manifest on the battery surface, particularly evident in cylindrical cells. Current thermal management systems for automotive battery packs solely rely on surface temperature measurements, neglecting the approximately 5.8°C temperature difference between the core and surface in TMS control. Consequently, changes in the battery's thermal state due to internal heat losses are not promptly detected by surface-mounted temperature sensors. This delayed response time accelerates battery degradation and increases the risk of thermal runaway events. In this study, temperature-informed fast charging algorithms, tested under various ambient conditions for LIBs, along with a comparative analysis, demonstrate that response time can be reduced by at least 2 minutes by considering internal temperature rather than relying solely on surface temperature measurements. Moreover, accounting for the temperature difference between the core and surface facilitates rapid TMS control and health-conscious fast charging, thereby mitigating the risk of thermal runaway events.
The aerodynamic interaction among rotors is a key phenomenon that influences the performance of the electric Vertical Takeoff and Landing (eVTOL) aircraft. This study applied Lattice-Boltzmann Method (LBM) to systemat...
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In this paper, we study unconstrained distributed optimization strongly convex problems, in which the exchange of information in the network is captured by a directed graph topology over digital channels that have lim...
In this paper, we study unconstrained distributed optimization strongly convex problems, in which the exchange of information in the network is captured by a directed graph topology over digital channels that have limited capacity (and hence information should be quantized). Distributed methods in which nodes use quantized communication yield a solution at the proximity of the optimal solution, hence reaching an error floor that depends on the quantization level used; the finer the quantization the lower the error floor. However, it is not possible to determine in advance the optimal quantization level that ensures specific performance guarantees (such as achieving an error floor below a predefined threshold). Choosing a very small quantization level that would guarantee the desired performance, requires information packets of very large size, which is not desirable (could increase the probability of packet losses, increase delays, etc) and often not feasible due to the limited capacity of the channels available. In order to obtain a communication-efficient distributed solution and a sufficiently close proximity to the optimal solution, we propose a quantized distributed optimization algorithm that converges in a finite number of steps and is able to adjust the quantization level accordingly. The proposed solution uses a finite-time distributed optimization protocol to find a solution to the problem for a given quantization level in a finite number of steps and keeps refining the quantization level until the difference in the solution between two successive solutions with different quantization levels is below a certain pre-specified threshold. Therefore, the proposed algorithm progressively refines the quantization level, thus eventually achieving low error floor with a reduced communication burden. The performance gains of the proposed algorithm are demonstrated via illustrative examples.
In this study, we implemented our entropy-based swarm model to an autonomous waypoint navigation application for a group of multi-rotor Unmanned Aerial Vehicles (UAVs) through a set course in free space. Multi-UAVs of...
In this study, we implemented our entropy-based swarm model to an autonomous waypoint navigation application for a group of multi-rotor Unmanned Aerial Vehicles (UAVs) through a set course in free space. Multi-UAVs of multiple group sizes were run with variations in parameters, and the path lengths traveled were measured to determine the most efficient configurations, and we investigated the impact of varying parameters on the swarm behavior performance. The simulation of the UAV kinematics and environment was performed in AirSim. The results show that the swarm model with different parameter setup operates successfully and the effects of the parameter selection on our multi-UAV swarm model are discussed.
This paper presents a comprehensive comparative study of two admittance prediction algorithms—data-driven and analytical—applied to Inverter-Based Resources (IBRs). The performance of these algorithms is compared us...
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ISBN:
(数字)9798350381832
ISBN:
(纸本)9798350381849
This paper presents a comprehensive comparative study of two admittance prediction algorithms—data-driven and analytical—applied to Inverter-Based Resources (IBRs). The performance of these algorithms is compared using a set of white-box IBR models, with the same training and test points employed for both to ensure a consistent basis for comparison. The study evaluates the effectiveness of these methods in accurately predicting the admittance of IBRs, emphasizing the influence of Operating Point (OP) variations on prediction accuracy. Performance evaluation is conducted through a "goodness of fit" metric. Additionally, this paper conducts a sensitivity analysis of the Analytical Prediction Method (APM), examining its adaptability across different control structures and parameters. Ultimately, this paper validates the APM using a generic black-box model, underlining its applicability and potential in real-world scenarios.
Reconfigurable Intelligent Surface (RIS) emerges as a promising technology for shaping the wireless propagation environment. In this paper, we introduce a novel Bayesian optimization framework to address the challenge...
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ISBN:
(数字)9798350369908
ISBN:
(纸本)9798350369915
Reconfigurable Intelligent Surface (RIS) emerges as a promising technology for shaping the wireless propagation environment. In this paper, we introduce a novel Bayesian optimization framework to address the challenge of joint channel estimation and optimization in complex wireless environments. To reduce the dimensionality of large-scale RIS, the framework incorporates a unique physics-informed structure embedding utilizing angular and spatial domain basis vectors. We validate our approach through laboratory experiments conducted with software-defined radio equipment, considering scenarios where the receivers are located in near-field or far-field regions. The results demonstrate superior channel gain per iteration compared to existing methods.
Autonomous helicopter aerial refueling is a challenging problem because of the complex aerodynamic interactions between the helicopter, the tanker and the refueling hose-drogue system. Methodologies solely relying on ...
Autonomous helicopter aerial refueling is a challenging problem because of the complex aerodynamic interactions between the helicopter, the tanker and the refueling hose-drogue system. Methodologies solely relying on model-based control approaches are unable to directly address the aerodynamic interactions, whereas pure data-driven methods such as reinforcement learning (RL) often do not provide safety guarantees. Therefore, in this paper, we propose a novel residual RL control methodology that works in conjunction with a model-based outer-loop position controller. Further, we incorporate a safe RL algorithm that assures probabilistic safety guarantees by imposing appropriate constraints. This algorithm leverages the primal-dual formulation of a constrained optimal control problem to solve a sequence of RL problems that ultimately guarantees a probabilistic safety assurance requirement. The RL agent is trained in a simulation platform that consists of a reduced-order helicopter model and a state-dependent control mixer that appropriately delegates the control authority between the outer-loop controller and the RL controller. Once trained, the RL agent is deployed on a physics-based high-fidelity helicopter model without additional parameter tuning. These high-fidelity simulations reveal that the application of the proposed methodology yields a mean 2-norm error of 0.25m at the time of docking, which outperforms a purely model-based controller by 24%.
Communicating a patient’s state accurately during transfer from emergency medical technicians to hospital personnel is crucial for optimal care. Prior work demonstrated automated algorithms that combined wearable sen...
Communicating a patient’s state accurately during transfer from emergency medical technicians to hospital personnel is crucial for optimal care. Prior work demonstrated automated algorithms that combined wearable sensors with video data from cameras to detect clinical procedures and improve this information transfer. However, incorporating video requires task-or environment-specific installation mechanisms, raises privacy concerns, and is susceptible to occlusion and image noise. The presented approach detects clinical procedures using wearable sensors (i.e., inertial and electrophysiological) only and the procedures’ subtasks to mitigate the sensors’ signal variability to provide clinical procedure detection.
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