- 标题
- 摘要
- 关键词
- 实验方案
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Surface-to-volume ratio drives photoelelectron injection from nanoscale gold into electrolyte
摘要： Hot charge carriers from plasmonic nanomaterials currently receive increased attention due to their promising potential in important applications such as solar water splitting. While a number of important contributions were made on plasmonic charge carrier generation and their transfer into the metal’s surrounding in the last decades, the local origin of those carriers is still unclear. With our study employing a nanoscaled bicontinous network of nanoporous gold, we take a comprehensive look at both subtopics in one approach and give unprecedented insights into the physical mechanisms controlling the broadband optical absorption and the generation and injection of hot electrons into an adjacent electrolyte where they enhance electrocatalytic hydrogen evolution. This absorption behavior is very different from the well-known localized surface plasmon resonance effects observed in metallic nanoparticles. For small ligament sizes the plasmon decay in our network is strongly enhanced via surface collisions of electrons. These surface collisions are responsible for the energy transfer to the carriers, thus, the creation of hot electrons from a broad spectrum of photon energies. As we reduce the gold ligament sizes below 30 nm, we demonstrate an occurring transition from absorption that is purely exciting 5d-electrons from deep below the Fermi level to an absorption which significantly excites “free” 6sp-electrons to be emitted. We differentiate these processes via assessing the internal quantum efficiency of the gold network photoelectrode as a function of the feature size providing a size-dependent understanding of the hot electron generation and injection processes in nanoscale plasmonic systems. We demonstrate that the surface effect - compared to the volume effect – becomes dominant and leads to significantly improved efficiencies. The most important fact to recognize is that in the surface photoeffect presented here, absorption and electron transfer are both part of the same quantum mechanical event.
关键词： Hot electron,Photoemission,Water splitting,Hydrogen evolution,Carrier injection,Surface damping,Nanoporous Au
更新于2025-10-22 19:40:53
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An Alternative Formulation for Optimum TMD Parameters Based on Equal Eigen Value Criteria
摘要： Closed form expressions for optimum Tuned Mass Damper (TMD) parameters are obtained by equating Eigen values of two modes and there is no need of any trial and error approach as used in earlier studies. For certain values of damping of main system and mass ratio, two sets of optimum parameters exist. For some other range of damping and mass ratio, modes become fully damped. In this range, optimum TMDs do not exist, and this happens for TMDs with large mass. The optimum TMD is shown to be quite robust and gives lesser TMD displacement as compared to optimum TMDs of earlier studies.
关键词： Equal modal frequency,Equal Eigen Value,Fully damped modes,Frequency response function,Optimum Tuned Mass Damper,Equal modal damping
更新于2025-09-23 15:23:52
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Simultaneous Fast Frequency Control and Power Oscillation Damping by Utilizing PV Solar System as PV-STATCOM
摘要： This paper presents a novel fast frequency response and power oscillation damping control by large-scale PV plants controlled as STATCOM, termed PV-STATCOM, to simultaneously enhance frequency regulation and small signal stability of power systems. Frequency deviations typically occur together with power oscillations in large power systems. The proposed controller comprises: i) Power Oscillation Damping (POD) controller based on reactive power modulation; and ii) Fast Frequency Response (FFR) controller based on real power modulation, both of which are applied to the plant level controller of PV-STATCOMs. The proposed composite control is shown to successfully reduce frequency deviations, damp power oscillations and provide voltage regulation both during over-frequency and under-frequency events. The proposed smart inverter control makes effective utilization of the PV inverter capacity and available solar power. For large power flows, the proposed control is shown to be superior than the conventional droop control recommended by North American Electric Reliability Corporation (NERC) for generating plants. Matlab/Simulink based simulations are conducted on two-area power system using generic PV plant dynamic models developed by Western Electricity Coordinating Council (WECC), for a wide range of system operating conditions. Such grid support functionality is expected to bring new revenue making opportunities for PV solar farms.
关键词： Power Oscillation Damping,Frequency control,Smart Inverters,Photovoltaic power plant
更新于2025-09-23 15:22:29
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Optimized decoherence suppression of tripartite entanglement in finite temperature environments using weak measurement and quantum measurement reversal
摘要： In practical application, since quantum entanglement is inevitably destroyed by thermal noise resulted from environment, protecting entanglement from decoherence in thermal bath environment becomes a critically important issue in the field of quantum information. In this work, we propose a scheme to protect the tripartite Greenberger–Horne–Zeilinger (GHZ) entanglement state subjected to the generalized amplitude damping (GAD) channel based on the quantum technique of weak measurement (WM) and quantum measurement reversal (QMR). By optimizing the strengths of WM and QMR, the decoherence caused by the channel can be effectively suppressed. The results show that after performing the optimal pre- and post-channel weak measurement, the negativity of the GHZ state can be effectively improved with a certain probability, and the phenomenon of sudden death can be delayed to a certain degree. This scheme can be applied to the decoherence suppression of GAD channel at finite temperature.
关键词： generalized amplitude damping channel,weak measurement,Decoherence suppression,tripartite entanglement.
更新于2025-09-23 15:22:29
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Compressive Phase Retrieval Realized by Combining Generalized Approximate Message Passing with Cartoon-Texture Model
摘要： Generalized approximate message passing (GAMP) can be applied to compressive phase retrieval (CPR) with excellent phase-transition behavior. In this paper, we introduced the cartoon-texture model into the denoising-based phase retrieval GAMP(D-prGAMP), and proposed a cartoon-texture model based D-prGAMP (C-T D-prGAMP) algorithm. Then, based on experiments and analyses on the variations of the performance of D-PrGAMP algorithms with iterations, we proposed a 2-stage D-prGAMP algorithm, which makes tradeoffs between the C-T D-prGAMP algorithm and general D-prGAMP algorithms. Finally, facing the non-convergence issues of D-prGAMP, we incorporated adaptive damping to 2-stage D-prGAMP, and proposed the adaptively damped 2-stage D-prGAMP (2-stage ADD-prGAMP) algorithm. Simulation results show that, runtime of 2-stage D-prGAMP is relatively equivalent to that of BM3D-prGAMP, but 2-stage D-prGAMP can achieve higher image reconstruction quality than BM3D-prGAMP. 2-stage ADD-prGAMP spends more reconstruction time than 2-stage D-prGAMP and BM3D-prGAMP. But, 2-stage ADD-prGAMP can achieve PSNRs 0.2 ～ 3 dB higher than those of 2-stage D-prGAMP and 0.3 ～ 3.1 dB higher than those of BM3D-prGAMP.
关键词： cartoon-texture model,generalized approximate message passing,adaptive damping,compressive phase retrieval
更新于2025-09-23 15:22:29
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Love-type waves in a piezoelectric-viscoelastic bimaterial composite structure due to an impulsive point source
摘要： The analysis of wave propagation phenomenon piezoelectric-viscoelastic composites still remains an unexplored field of research. The usage of a passive polymer (Epoxy) with active piezoelectric ceramic causes viscoelasticity in the piezoelectric material which results into a piezoelectric-viscoelastic composite. The present study aims to analyze the propagation behavior of Love-type wave in an exponentially graded piezoelectric-viscoelastic material (EGPVM) stratum lying over a functionally graded piezoelectric-viscoelastic material (FGPVM) substrate due to an impulsive point source at its interfacial surface. The electro-visco-mechanical field equations are laid down for the piezoelectric-viscoelastic medium.The analytical solution procedure involves the use of suitable Green’s function and admissible boundary conditions. The established frequency equation is in complex form; of which the real expression imparts the frequency curve and imaginary expression gives the attenuation curve of Love-type wave. To depict the results numerically, two distinct piezoelectric-viscoelastic materials (Epoxy-BNKLBTand Epoxy-KNLNTSceramics) for EGPVM stratum and FGPVM substrate are taken into account.The phase velocity profile and attenuation coefficient profile of Love-type wave is portrayed graphically. Diagnostic results are simulated numerically which forefronts the effect of distinct parameters. The study manifests the impact of the material medium parameters, viz. piezoelectric constants, dielectric constants, piezoelectric loss moduli, dielectric loss moduli, exponential gradient parameter and magnifying gradient parameters on the phase velocity and attenuation coefficient of Love-type wave. For sake of validation, the obtained results are matched with the classical one, as a special case of the problem. The outcomes of the study may find its worth in better and optimum design of surface acoustic wave devices and Love wave sensors, keeping efficiency at its premium.
关键词： Piezoelectric-viscoelastic,damping equation,frequency equation,point source,Green’s function,attenuation coefficient.
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - Portland, OR, USA (2018.9.23-2018.9.27)] 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - Power Factor Operation of a Boost Integrated Three-Phase Solar Inverter using Current Unfolding and Active Damping Methods
摘要： This paper proposes a three-phase solar inverter with integrated boost function. The circuit operating principle is based on current unfolding and injection method. This approach requires only two high frequency switches for the boost function as well as shaping its output currents, thus leading to a significant reduction in switching losses. Other switches only operate at line frequency to unfold the output currents to sinusoidal three-phase currents, and thus can be optimized to reduce conduction losses. The proposed inverter therefore could deliver high efficiency. This paper discusses the basic operating principle and control method for the inverter. The paper proposes an active damping method to overcome intrinsic oscillation due to overlapping time in switching operation. It also shows that the inverter is capable of supplying reactive power up to a limit of 0.866 power factor. Stable operation of the proposed inverter is confirmed by both simulation and experiment.
关键词： current unfolding,active damping,three-phase inverter,oscillation
更新于2025-09-23 15:22:29
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[IEEE 2018 OCEANS - MTS/IEEE Kobe Techno-Ocean (OTO) - Kobe (2018.5.28-2018.5.31)] 2018 OCEANS - MTS/IEEE Kobe Techno-Oceans (OTO) - Research on Virtual Synchronous Generator Technology Introduced into Solar Ship
摘要： Because of the advantages of energy-saving and emission-reduction, green ships have attracted wide attention from all over the world. At present, the use of renewable energy for all or part of the ship's power supply equipment research, most of the reference or apply the research experience of terrestrial photovoltaic system. In real sailing, the ship’s attitude will change over time because of ocean winds, waves, current and the ship’s moving and rocking. Due to these factors, the irradiance on the ship PV panels is changing with time. The fluctuating power caused by the moving and rocking of ships will also change. In this paper, we presents a new idea of applying a virtual synchronous generator (VSG) technology to a ship, which can stabilize the partial fluctuation power caused by the moving and rocking of the ship. The VSG control strategy can show the characteristics of the synchronous generator (SG) by controlling the distributed power supply. Through virtual inertia and damping links of the VSG to stabilize the fluctuations caused by photovoltaic panels’ moving and rocking on the deck. Here illustrate some key process in this paper. Firstly, considering factors such as wind, wave and flow, the model of photovoltaic power generation in ship is established. Secondly, the VSG is introduced into the solar ship and the virtual inertia and damping coefficient in the VSG are designed by the actual situation. Thirdly, combining the discussion of the actual route from Shanghai to Sydney, simulations are used to verify the effectiveness of the method. Through the above method, not only the volume of the energy storage device and the number of charging and discharging times can be reduced, but also precious ship space can be saved and the stability of the power grid can be improved. New energy power generation equipment can approach the ship power system similar to the SG. Drawing on the experience of the SG power supply system, new energy can be better integrated into the ship power station for management and control.
关键词： Solar ship,Virtual synchronous generator,Virtual inertia and damping coefficient,Ship-swaying
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Conference on Semiconductor Electronics (ICSE) - Kuala Lumpur (2018.8.15-2018.8.17)] 2018 IEEE International Conference on Semiconductor Electronics (ICSE) - Dynamic Behavior of Condenser Microphone Under the Influence of Squeeze Film Damping
摘要： This paper investigates the effect of squeeze film damping on a micromechanical structure that oscillates due to the pressure distribution on moveable top plate that pair with perforated backplate. The damping characteristics are analytically evaluated to establish the optimum design that increase dynamics performance. The squeezed film damping governing equation, the Reynolds equation, is the fundamental equation of this work. The damping coefficient, air gap damping and viscous damping are calculated by using Skvor’s formula. The size of perforation holes and air gap thickness that influencing the squeeze film damping were studied. Analytical solution with various holes structure are summarized. Overall, the 3μm of hole radius, 50μm of holes center-to-center distance and 4μm of air gap thickness were found to be the best in order to reduce squeeze film damping in capacitive microphone.
关键词： perforated structure,viscous damping,squeeze film damping
更新于2025-09-23 15:21:21
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[IEEE 2019 International Council on Technologies of Environmental Protection (ICTEP) - Star?? Smokovec, Slovakia (2019.10.23-2019.10.25)] 2019 International Council on Technologies of Environmental Protection (ICTEP) - The Statistical Measurements of Photovoltaic Panels Degradation
摘要： State-space current control enables high dynamic performance of a three-phase grid-connected converter equipped with an LCL filter. In this paper, observer-based state-space control is designed using direct pole placement in the discrete-time domain and in grid-voltage coordinates. Analytical expressions for the controller and observer gains are derived as functions of the physical system parameters and design specifications. The connection between the physical parameters and the control algorithm enables automatic tuning. Parameter sensitivity of the control method is analyzed. The experimental results show that the resonance of the LCL filter is well damped, and the dynamic performance specified by direct pole placement is obtained for the reference tracking and grid-voltage disturbance rejection.
关键词： parameter sensitivity,Active damping,LCL filter,sensorless state feedback,grid-connected converter,current control
更新于2025-09-23 15:21:01