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• A rolling magnetic spring energy harvester is proposed for handshaking. • The influence of the coil's position on output performance is investigated. • Excitation with a level of 0.3 g witnesses a half-power bandwidth of 1.61 Hz. • Maximum average power of 2.22 mW is achieved under handshaking excitation. • Handshaking excitation in 5 s could enable a watch to operate for 1100 s. Aiming at the random and low-frequency characteristics of human motion, a hand-held rolling magnetic-spring energy harvester is proposed to scavenge energy from handshaking. The harvester applies the rolling movement of a magnetically suspended magnet and possesses the merit of low damping. The dynamic model is established and the open-circuit voltages are predicted by combining Faraday's law of electromagnetic induction and finite element analysis. By calculating magnetic flux through coils, the effect of the coil's position on energy harvesting efficiency is studied through numerical and experimental approaches. Experimental results under harmonic excitations indicate that the coil positioned directly below the stable equilibrium position of the moving magnet has the best output capability, and a maximum open-circuit voltage of 1.33 V and a half-power bandwidth of 1.61 Hz is achieved at 0.3 g. Under handshaking excitation, an instantaneous peak power of 20.15 mW is achieved, along with a maximum average power of 2.22 mW. The corresponding volume and mass power densities are respectively 26.04 μW/cm3 and 23.28 μW/g. Furthermore, handshaking excitation in 5 s to charge a capacitor of 470 μF could enable the watch, time display, timer, and hygrothermograph to operate for 1100 s, 513 s, 86 s, and 35 s respectively, demonstrating the brilliant application foreground of the proposed harvester. [ABSTRACT FROM AUTHOR]

• A magnetic rolling pendulum bistable harvester is proposed for handshaking. • Complex dynamic behaviors and multiple solutions of the system are emphasized. • Bandwidth for high-energy orbit oscillation is 4.84 Hz under excitation of 0.5 g. • Matched impedance sees an average power of 4.21 mW under handshaking excitation. • Handshaking vibration in 13 s to charge a capacitor powers a watch for 44 min. Converting the kinetic energy of human movement into electricity provides a solution for the power supply of portable electronics for communication, medical treatment, positioning, search-and-rescue, etc. Due to the characteristics of high sensitivity and snap-through, a magnetic rolling pendulum bistable energy harvester (MRP-BEH) based on magnetic-spring mechanism is proposed for scavenging energy from handshaking vibration. The harvester possessing the advantage of small damping exploits the rolling oscillation of a suspended magnet. By establishing the electromechanical model, numerical outcomes of the MRP-BEHs with different potential well depths are investigated through the response under constant and sweep frequency excitations. Particularly, the complex dynamic behaviors are characterized by basins of attraction and bifurcation diagrams. A prototype is fabricated, and experiments are undertaken under harmonic and handshaking excitations. Experimental results are consistent with numerical simulations, and excitation of 0.5 g witnesses a broadband frequency range from 5.18 Hz to 10.02 Hz for the harvester with proper system parameters. Regarding the excitation of handshaking, an instantaneous maximum power of 21.9 mW and an average power of 4.21 mW is achieved with matched load resistance. By boosting the output voltage with a transformer, the charging and discharging experiments of capacitors for powering various electronics demonstrate the broad application prospects of the harvester. This research, in a nutshell, broadens the methodology for achieving bistable oscillation and introduces a fresh perspective for designing high-efficiency energy harvesters attuned to human motion. [ABSTRACT FROM AUTHOR]

• A new optimal mileage-based PV array reconfiguration (OMAR) is constructed. • The OMAR can maximize the total benefit instead of only the generation benefit. • The OMAR decomposition with two sub-problems reduces the optimization difficulty. • The swarm reinforcement learning is used to obtain high-quality optimums of OMAR. • The proposed method can obtain higher total benefit than 6 comparative algorithms. This paper constructs a new optimal mileage-based PV array reconfiguration (OMAR) in a PV power plant under partial shading conditions. It aims to maximize the power output of a PV power plant, and minimize the additional capacity and mileage payments resulting from the power fluctuation in a performance-based frequency regulation market. To reduce the optimization difficulty of OMAR, it is decomposed into two optimization sub-problems, including an upper-layer discrete optimization of PV array reconfiguration and a lower-layer continuous optimization of real-time generation scheduling. The upper-layer discrete optimization is addressed by the proposed swarm reinforcement learning (SRL), which can implement an efficient exploration and exploitation with multiple cooperative agents instead of a single learning agent. The rest lower-layer optimization is handled by the fast interior point method. The proposed method's effectiveness is thoroughly evaluated on the 10 × 10 total-cross-tied PV arrays under various partial shading conditions. Simulation results demonstrate that the proposed SRL can obtain a larger total benefit than genetic algorithm (GA), particle swarm optimization (PSO), grasshopper optimization algorithm (GOA), harris hawks optimizer (HHO), butterfly optimization algorithm (BOA), and Q-learning, in which the benefit increment can reach from 2.12% (against PSO) to 10.62% (against Q-learning). [ABSTRACT FROM AUTHOR]