Nanoporous BiVO;thin films were deposited using reactive magnetron sputtering in Ar and O;atmosphere, on various substrates, employing pulsed direct-current(DC) power supplies applied to metallic Bi and V targets for ...Nanoporous BiVO;thin films were deposited using reactive magnetron sputtering in Ar and O;atmosphere, on various substrates, employing pulsed direct-current(DC) power supplies applied to metallic Bi and V targets for rapid deposition. The procedure was followed by a post-annealing treatment in air to crystallize the photoactive monoclinic scheelite structure. The influence of total pressure and substrate on the crystal structure, morphology, microstructure, optical and photocatalytic properties of the films was investigated. The crystallization of monoclinic scheelite structure deposited on fused silica substrate starts at 250 ℃ and the films are stable up to 600 ℃. The morphology of the films is rather dense, despite at the high sputtering pressure(>2 Pa), with embedded nanopores. Among the thin films deposited on fused silica, the one deposited at 4.5 Pa exhibits the highest porosity(52%), with the lowest bandgap(2.44 eV) and it shows the highest photocatalytic activity in the degradation of Rhodamine-B(26% after 7 h) under visible light irradiation. The film deposited on the silicon substrate exhibits the highest photoactivity(53% after 7 h). Lack of hypsochromic shift in the UV-Vis temporal absorption spectra shows the dominance of the chromophore cleavage pathway in the photodecomposition.展开更多
The characterization of finite length Surface Acoustic Wave (SAW) and Bulk acoustic Wave (BAW) resonators is addressed here. The Finite Element Analysis (FEA) induces artificial wave reflections at the edges of the me...The characterization of finite length Surface Acoustic Wave (SAW) and Bulk acoustic Wave (BAW) resonators is addressed here. The Finite Element Analysis (FEA) induces artificial wave reflections at the edges of the mesh. In fact, these ones do not contribute in practice to the corresponding experimental response. The Perfectly Matched Layer (PML) method, allows to suppress the boundary reflections. In this work, we first demonstrate the basis of PML adapted to FEA formalism. Next, the results of such a method are depicted allowing a discussion on the behavior of finite acoustic resonators.展开更多
Infrared camouflage based on artificial thermal metasurfaces has recently attracted significant attention.By eliminating thermal radiation differences between the object and the background,it is possible to hide a giv...Infrared camouflage based on artificial thermal metasurfaces has recently attracted significant attention.By eliminating thermal radiation differences between the object and the background,it is possible to hide a given object from infrared detection.Infrared camouflage is an important element that increases the survivability of aircraft and missiles,by reducing target susceptibility to infrared guided threats.Herein,a simple and practicable design is theoretically presented based on a multilayer film for infrared stealth,with distinctive advantages of scalability,flexible fabrication,and structural simplicity.The multilayer medium consists of silicon substrate,carbon layer and zinc sulfide film,the optical properties of which are determined by transfer matrix method.By locally changing the thickness of the coating film,the spatial tunability and continuity in thermal emission are demonstrated.A continuous change of emissive power is further obtained and consequently implemented to achieve thermal camouflage functionality.In addition,other functionalities,like thermal illusion and thermal coding,are demonstrated by thickness-engineered multilayer films.展开更多
We propose in this paper the design of artificial nanostructure chirality obtained by oblique illumination. This structure is based on anisotropic metamaterial having an optical activity induced by the special geometr...We propose in this paper the design of artificial nanostructure chirality obtained by oblique illumination. This structure is based on anisotropic metamaterial having an optical activity induced by the special geometry of the pattern and the incident beam. Starting from a non-chiral material, the artificial chirality is obtained thanks to the rectangular apertures which form the periodic perfect metal nanostructure （one layer） and the oblique incidence of the light beam. An extraordinary light transmission （93%） through the metal nanostructure is achieved by exciting the cavity modes. The extrinsic chirality obtained can be granted to the desired value by appropriately adjusting the geometric parameters and the angle of incidence.展开更多
In this paper,a set of distributed secondary controllers is introduced that provide active regulation for both steady-state and transient-state performances of an islanded DC microgrid(MG).The secondary control for di...In this paper,a set of distributed secondary controllers is introduced that provide active regulation for both steady-state and transient-state performances of an islanded DC microgrid(MG).The secondary control for distributed converter interfaced generation(DCIG)not only guarantees that the system converges to the desired operating states in the steady state but also regulates the state variations to a prescribed transient-state performance.Compared with state-of-the-art techniques of distributed secondary control,this paper achieves accurate steady-state secondary regulations with prescribed transient-state performance in an islanded DC MG.Moreover,the applicability of the proposed control does not rely on any explicit knowledge of the system topology or physical parameters.Detailed controller designs are provided,and the system under control is proved to be Lyapunov stable using large-signal stability analysis.The steady-state and transient-state performances of the system are analyzed.The paper proves that as the perturbed system converges,the proposed control achieves accurate proportional power sharing and average voltage regulation among the DCIGs,and the transient variations of the operating voltages and power outputs at each DCIG are regulated to the prescribed transient-state performance.The effectiveness of the proposed control is validated via a four-DCIG MG system.展开更多
Proton Exchange Membrane(PEM)electrolysis stands as a cornerstone technology in the clean energy sector,driving the production of hydrogen and oxygen from water.A critical aspect of ensuring the efficiency and safety ...Proton Exchange Membrane(PEM)electrolysis stands as a cornerstone technology in the clean energy sector,driving the production of hydrogen and oxygen from water.A critical aspect of ensuring the efficiency and safety of this process lies in the precise monitoring and control of temperature at the electrolysis outlet.However,accurately characterizing temperature changes within the PEM electrolysis system can be challenging due to the fluctuation of renewable energies.This study introduces an approach integrating data with fundamental physics principles known as Physics-Informed Neural Networks(PINNs).This method solves differential equations and estimates the unknown parameters governing the temperature dynamics within the PEM electrolysis system.We consider two distinct scenarios:a zero-dimensional model and a one-dimensional model.The results demonstrate the PINN’s proficiency in accurately identifying the parameters and solving for temperature fluctuations within the system with different input conditions.Furthermore,we compare the PINN with the Long Short-Term Memory(LSTM)method to predict the outlet temperature of the electrolysis.The PINN outperformed the LSTM method,highlighting its reliability and precision,achieving a Mean Squared Error(MSE)of 0.1596 compared to 1.2132 for LSTM models.The proposed method shows a high performance in dealing with sensor noises and avoids overfitting problems.This synergy of physics knowledge and data-driven learning opens new pathways towards real-time digital twins,enhanced predictive control,and improved reliability for PEM electrolysis and other complex,data-scarce energy systems.展开更多
Researchers often face difficulties in organizing and structuring their research data.Moreover,today,these data must respect the FAIR principles.To overcome these problems,in the environmental domain,the Meta-Obs proj...Researchers often face difficulties in organizing and structuring their research data.Moreover,today,these data must respect the FAIR principles.To overcome these problems,in the environmental domain,the Meta-Obs project proposes a metamodel,a methodology and a tool that generates a”FAIRizable”database.The obtained database is adapted to the needs of the researcher and is enriched with metadata.In this article we present Meta-Obs and we illustrate its use with a concrete case:the design of the database of the Aspergillus fumigatus collection.展开更多
The transition to sustainable and environmentally friendly energy sources is a crucial step in our global effort to reduce carbon emissions.In this context,fuel cell technology has emerged as a leading innovative solu...The transition to sustainable and environmentally friendly energy sources is a crucial step in our global effort to reduce carbon emissions.In this context,fuel cell technology has emerged as a leading innovative solution,offering a promising alternative to conventional fossil fuel-based systems.It aims to achieve zero emissions while maintaining high efficiency and performance.Although fuel cell technology holds great potential for a sustainable and clean energy future,its widespread adoption is still hindered by several challenges.These include improving the efficiency and durability of fuel cells,as well as further enhancing their power output.To address these challenges,various design innovations and optimization strategies have been proposed to tackle the practical issues encountered in real-world applications.This special issue aims to provide a platform for researchers,engineers,and policymakers to present their latest scientific findings or engineering experiences in the development and application of new technologies to overcome the challenges in fuel cell application.展开更多
In this paper,the synchronous rotor speed control problem of multiple permanent magnet synchronous motors(PMSMs)with port-Hamiltonian(PH)dynamics is investigated.First,the synchronous rotor speed problem is reformulat...In this paper,the synchronous rotor speed control problem of multiple permanent magnet synchronous motors(PMSMs)with port-Hamiltonian(PH)dynamics is investigated.First,the synchronous rotor speed problem is reformulated as an optimization problem and a distributed controller is proposed for each PMSM.Then,the stability of the closed-loop system is analyzed,and it is proven that its equilibrium aligns with the optimum of the value function derived from the optimization problem.Based on the proposed distributed controller,PMSMs exchange the estimated average rotor speed with their neighbours,rather than the direct rotor speed,which benefits the protection of the sensitive state variables.Finally,a simulation example is presented to validate the effectiveness of the proposed distributed controller.展开更多
Impedance metasurfaces enable accurate regulation of acoustic fields.However,they can hardly supply a flexible response as such perfect operation is accompanied by stringent requirements on the design of unit cells.Ac...Impedance metasurfaces enable accurate regulation of acoustic fields.However,they can hardly supply a flexible response as such perfect operation is accompanied by stringent requirements on the design of unit cells.Actually,an arbitrary lossless and passive target impedance matrix requires the tuning of 3 independent real parameters.The set composed of a reflection phase,a transmission amplitude,and a transmission phase,enables the representation of an arbitrary impedance matrix,possibly possessing singular elements.In this paper,a mechanism of phase-amplitude-phase modulation(PAP modulation)is developed for the generic design of the unit cells of acoustic impedance metasurfaces.Adjustable acoustic impedance metasurfaces are further available under this framework.An impedance unit with 3 mobile parts is designed based on this idea.The assembled metasurface can handle different incidences for acoustic field manipulation at a given frequency.Beam steering and beam splitting are considered as demonstration examples and are verified by numerical simulation and experiment.PAP modulation enriches the design of acoustic impedance metasurfaces and extends the range of application of impedance theory.展开更多
With the growing global energy demand and the pursuit of sustainable energy,solar energy has received widespread attention as a clean and renewable energy source.A structural design of an inflatable,large-scale solar ...With the growing global energy demand and the pursuit of sustainable energy,solar energy has received widespread attention as a clean and renewable energy source.A structural design of an inflatable,large-scale solar concentrating reflector based on in-orbit assembly is proposed in this paper.The axisymmetric inflated reflector surface is inversely designed through membrane mechanics,and the internal pressures to maintain the reflector surface morphology at different orbital positions and the tiny deformation produced by the reflecting surface under the action of the uniform pressure are determined.A inflatable-rigidizable support structure is prepared by using a rigidizable aramid fabric-reinforced composite.The support structure used to the parabolic reflecting surface is designed,and the diameter and spacing distance of the resistance wire of the heating layer are determined by electrothermal simulation;the combination of solar radiation and electric heating is used to rigidize the reflector in orbit,and the corresponding electric heating time at different orbital positions is also analyzed by in orbit simulation.The heating voltage,folding radius and folding method of the rigidizable support structure are determined through the experimental design,and the folding and deployment experiments are carried out by using the heating and internal pressure and the final shape recovery rate of the support tube is approximately 100%,which verifies the feasibility of its folding and deployment.展开更多
Thermal metamaterials represent a transformative paradigm in modern physics,synergizing thermodynamic principles with metamaterial engineering to master heat flow at will.As next-generation technologies demand multi-s...Thermal metamaterials represent a transformative paradigm in modern physics,synergizing thermodynamic principles with metamaterial engineering to master heat flow at will.As next-generation technologies demand multi-scale thermal control,this field urgently requires systematic frameworks to unify its multidisciplinary advances.Curated through a global collaboration involving over 50 specialists across 25 subdisciplines,this review primarily summarizes two decades of advancements,ranging from theoretical breakthroughs to functional implementations.The review reveals groundbreaking innovations in heat manipulation through the exploration of both classical and non-classical transport regimes,topological thermal control mechanisms,and quantum-informed phonon engineering strategies.By bridging physical insights like non-Hermitian thermal dynamics and valleytronic phonon transport with cutting-edge applications,we demonstrate paradigm-shifting capabilities:environment-adaptive thermal cloaks,AI-optimized metamaterials,and nonlinear thermal circuits enabling heat-based computation.Experimental milestones include 3D thermal null media with reconfigurable invisibility and thermal designs breaking classical conductivity limits.This collaborative effort establishes an indispensable roadmap for physicists,highlighting pathways to quantum thermal management,entropy-controlled energy systems,and topological devices.As thermal metamaterials transition from laboratory marvels to technological cornerstones,this work provides the foundational lexicon and design principles for the coming era of intelligent thermal matter.展开更多
A coordinated scheduling model based on two-stage distributionally robust optimization(TSDRO)is proposed for integrated energy systems(IESs)with electricity-hydrogen hybrid energy storage.The scheduling problem of the...A coordinated scheduling model based on two-stage distributionally robust optimization(TSDRO)is proposed for integrated energy systems(IESs)with electricity-hydrogen hybrid energy storage.The scheduling problem of the IES is divided into two stages in the TSDRO-based coordinated scheduling model.The first stage addresses the day-ahead optimal scheduling problem of the IES under deterministic forecasting information,while the sec-ond stage uses a distributionally robust optimization method to determine the intraday rescheduling problem under high-order uncertainties,building upon the results of the first stage.The scheduling model also considers col-laboration among the electricity,thermal,and gas networks,focusing on economic operation and carbon emissions.The flexibility of these networks and the energy gradient utilization of hydrogen units during operation are also incor-porated into the model.To improve computational efficiency,the nonlinear formulations in the TSDRO-based coordinated scheduling model are properly linearized to obtain a Mixed-Integer Linear Programming model.The Column-Constraint Generation(C&CG)algorithm is then employed to decompose the scheduling model into a mas-ter problem and subproblems.Through the iterative solution of the master problem and subproblems,an efficient analysis of the coordinated scheduling model is achieved.Finally,the effectiveness of the proposed TSDRO-based coordinated scheduling model is verified through case studies.The simulation results demonstrate that the proposed TSDRO-based coordinated scheduling model can effectively accomplish the optimal scheduling task while consider-ing the uncertainty and flexibility of the system.Compared with traditional methods,the proposed TSDRO-based coordinated scheduling model can better balance conservativeness and robustness.展开更多
Femtosecond pulses from an ultrafast mode-locked fiber laser can be optimized in real time by combining single-shot spectral measurements with a smart genetic algorithm to actively control and drive the intracavity dy...Femtosecond pulses from an ultrafast mode-locked fiber laser can be optimized in real time by combining single-shot spectral measurements with a smart genetic algorithm to actively control and drive the intracavity dynamics.展开更多
In this paper, we present an ultra-compact 1D photonic crystal(Ph C) Bragg grating design on a thin film lithium niobate slot waveguide(SWG) via 2D-and 3D-FDTD simulations. 2D-FDTD simulations are employed to tune the...In this paper, we present an ultra-compact 1D photonic crystal(Ph C) Bragg grating design on a thin film lithium niobate slot waveguide(SWG) via 2D-and 3D-FDTD simulations. 2D-FDTD simulations are employed to tune the photonic bandgap(PBG) size, PBG center, cavity resonance wavelength, and the whole size of Ph C. 3DFDTD simulations are carried out to model the real structure by varying different geometrical parameters such as SWG height and Ph C size. A moderate resonance quality factor Q of about 300 is achieved with a Ph C size of only 0.5 μm× 0.7 μm× 6 μm. The proposed slot Bragg grating structure is then exploited as an electric field(E-field) sensor. The sensitivity is analyzed by 3D-FDTD simulations with a minimum detectable E-field as small as 23 m V∕m. The possible fabrication process of the proposed structure is also discussed. The compact size of the proposed slot Bragg grating structure may have applications in on-chip E-field sensing, optical filtering, etc.展开更多
The Year 2020 represents 60 years since the first successful operation of the laser.This anniversary provides an ideal occasion to reflect on the myriad ways that lasers have revolutionized society,and to consider the...The Year 2020 represents 60 years since the first successful operation of the laser.This anniversary provides an ideal occasion to reflect on the myriad ways that lasers have revolutionized society,and to consider the many new areas of research that continue to drive photonics in unexpected directions.Yet at the same time as we consider these exciting future perspectives,it is also interesting to see how the development of the laser traces a path that intertwines basic and applied science,and intersects with the recognition of many of the pioneers of optics through the Nobel Prize.Of course,an exhaustive history of such a rich topic cannot be given in a short Perspective,but it is perhaps possible to describe some of the key highlights.展开更多
In the paper,a novel self-learning energy management strategy(EMS)is proposed for fuel cell hybrid electric vehicles(FCHEV)to achieve the hydrogen saving and maintain the battery operation.In the EMS,it is proposed to...In the paper,a novel self-learning energy management strategy(EMS)is proposed for fuel cell hybrid electric vehicles(FCHEV)to achieve the hydrogen saving and maintain the battery operation.In the EMS,it is proposed to approximate the EMS policy function with fuzzy inference system(FIS)and learn the policy parameters through policy gradient reinforcement learning(PGRL).Thus,a so-called Fuzzy REINFORCE algorithm is first proposed and studied for EMS problem in the paper.Fuzzy REINFORCE is a model-free method that the EMS agent can learn itself through interactions with environment,which makes it independent of model accuracy,prior knowledge,and expert experience.Meanwhile,to stabilize the training process,a fuzzy baseline function is adopted to approximate the value function based on FIS without affecting the policy gradient direction.More-over,the drawbacks of traditional reinforcement learning such as high computation burden,long convergence time,can also be overcome.The effectiveness of the proposed methods were verified by Hardware-in-Loop ex-periments.The adaptability of the proposed method to the changes of driving conditions and system states is also verified.展开更多
Acoustic wave resonators are promising candidates for gravimetric biosensing.However,they generally suffer from strong acoustic radiation in liquid,which limits their quality factor and increases their frequency noise...Acoustic wave resonators are promising candidates for gravimetric biosensing.However,they generally suffer from strong acoustic radiation in liquid,which limits their quality factor and increases their frequency noise.This article presents an acoustic radiation-free gravimetric biosensor based on a locally resonant surface phononic crystal(SPC)consisting of periodic high aspect ratio electrodes to address the above issue.The acoustic wave generated in the SPC is slower than the sound wave in water,hence it prevents acoustic propagation in the fluid and results in energy confinement near the electrode surface.This energy confinement results in a significant quality factor improvement and reduces frequency noise.The proposed SPC resonator is numerically studied by finite element analysis and experimentally implemented by an electroplating-based fabrication process.Experimental results show that the SPC resonator exhibits an in-liquid quality factor 15 times higher than a conventional Rayleigh wave resonator at a similar operating frequency.The proposed radiation suppression method using SPC can also be applied in other types of acoustic wave resonators.Thus,this method can serve as a general technique for boosting the in-liquid quality factor and sensing performance of many acoustic biosensors.展开更多
基金the supports of this study by the Iran National Science Foundation (No. 98001285)Pays de Montbéliard Agglomération (France) for the support of this work。
文摘Nanoporous BiVO;thin films were deposited using reactive magnetron sputtering in Ar and O;atmosphere, on various substrates, employing pulsed direct-current(DC) power supplies applied to metallic Bi and V targets for rapid deposition. The procedure was followed by a post-annealing treatment in air to crystallize the photoactive monoclinic scheelite structure. The influence of total pressure and substrate on the crystal structure, morphology, microstructure, optical and photocatalytic properties of the films was investigated. The crystallization of monoclinic scheelite structure deposited on fused silica substrate starts at 250 ℃ and the films are stable up to 600 ℃. The morphology of the films is rather dense, despite at the high sputtering pressure(>2 Pa), with embedded nanopores. Among the thin films deposited on fused silica, the one deposited at 4.5 Pa exhibits the highest porosity(52%), with the lowest bandgap(2.44 eV) and it shows the highest photocatalytic activity in the degradation of Rhodamine-B(26% after 7 h) under visible light irradiation. The film deposited on the silicon substrate exhibits the highest photoactivity(53% after 7 h). Lack of hypsochromic shift in the UV-Vis temporal absorption spectra shows the dominance of the chromophore cleavage pathway in the photodecomposition.
文摘The characterization of finite length Surface Acoustic Wave (SAW) and Bulk acoustic Wave (BAW) resonators is addressed here. The Finite Element Analysis (FEA) induces artificial wave reflections at the edges of the mesh. In fact, these ones do not contribute in practice to the corresponding experimental response. The Perfectly Matched Layer (PML) method, allows to suppress the boundary reflections. In this work, we first demonstrate the basis of PML adapted to FEA formalism. Next, the results of such a method are depicted allowing a discussion on the behavior of finite acoustic resonators.
基金supported by the EIPHI Graduate School(Grant No.ANR-17-EURE-0002)the U.S.National Science Foundation(Grant Nos.DMR-1823800,CMMI-2131760 and CMMI-1930873).
基金support by the China Scholarship Council(CSC).This research has additionally been funded by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)under Germany’s Excellence Strategy via the Excellence Cluster“3D Matter Made to Order”(Grant No.EXC-2082/1-390761711)which has also been supported by the Carl Zeiss Foundation through the“Carl-Zeiss-Foundation-Focus@HEiKA”,by the State of Baden-Württemberg,and by the Karlsruhe Institute of Technology(KIT).We further acknowledge support by the Helmholtz program“Materials Systems Engineering”(MSE).Muamer Kadic is grateful for support by the EIPHI Graduate School(Grant No.ANR-17-EURE-0002)Changguo Wang is grateful for support by the National Natural Science Foundation of China(Grant No.12172102).
基金supported by the EIPHI Graduate School(No.ANR-17-EURE-0002)the French Investissements d’Avenir program,project ISITEBFC(No.ANR-15-IDEX-03)+1 种基金the National Natural Science Foundation of China(Nos.12172102,11872160 and 11732002)the support of the Alexander von Humboldt Foundation through the Feodor Lynen Fellowship。
文摘Infrared camouflage based on artificial thermal metasurfaces has recently attracted significant attention.By eliminating thermal radiation differences between the object and the background,it is possible to hide a given object from infrared detection.Infrared camouflage is an important element that increases the survivability of aircraft and missiles,by reducing target susceptibility to infrared guided threats.Herein,a simple and practicable design is theoretically presented based on a multilayer film for infrared stealth,with distinctive advantages of scalability,flexible fabrication,and structural simplicity.The multilayer medium consists of silicon substrate,carbon layer and zinc sulfide film,the optical properties of which are determined by transfer matrix method.By locally changing the thickness of the coating film,the spatial tunability and continuity in thermal emission are demonstrated.A continuous change of emissive power is further obtained and consequently implemented to achieve thermal camouflage functionality.In addition,other functionalities,like thermal illusion and thermal coding,are demonstrated by thickness-engineered multilayer films.
文摘We propose in this paper the design of artificial nanostructure chirality obtained by oblique illumination. This structure is based on anisotropic metamaterial having an optical activity induced by the special geometry of the pattern and the incident beam. Starting from a non-chiral material, the artificial chirality is obtained thanks to the rectangular apertures which form the periodic perfect metal nanostructure （one layer） and the oblique incidence of the light beam. An extraordinary light transmission （93%） through the metal nanostructure is achieved by exciting the cavity modes. The extrinsic chirality obtained can be granted to the desired value by appropriately adjusting the geometric parameters and the angle of incidence.
基金supported in part by Fundamental Research Funds for the Central Universities,Northwestern Polytechnical University,and in part by Xianyang Key R&D Program(No.L2023-Z DYF-QYCX-012)。
文摘In this paper,a set of distributed secondary controllers is introduced that provide active regulation for both steady-state and transient-state performances of an islanded DC microgrid(MG).The secondary control for distributed converter interfaced generation(DCIG)not only guarantees that the system converges to the desired operating states in the steady state but also regulates the state variations to a prescribed transient-state performance.Compared with state-of-the-art techniques of distributed secondary control,this paper achieves accurate steady-state secondary regulations with prescribed transient-state performance in an islanded DC MG.Moreover,the applicability of the proposed control does not rely on any explicit knowledge of the system topology or physical parameters.Detailed controller designs are provided,and the system under control is proved to be Lyapunov stable using large-signal stability analysis.The steady-state and transient-state performances of the system are analyzed.The paper proves that as the perturbed system converges,the proposed control achieves accurate proportional power sharing and average voltage regulation among the DCIGs,and the transient variations of the operating voltages and power outputs at each DCIG are regulated to the prescribed transient-state performance.The effectiveness of the proposed control is validated via a four-DCIG MG system.
文摘Proton Exchange Membrane(PEM)electrolysis stands as a cornerstone technology in the clean energy sector,driving the production of hydrogen and oxygen from water.A critical aspect of ensuring the efficiency and safety of this process lies in the precise monitoring and control of temperature at the electrolysis outlet.However,accurately characterizing temperature changes within the PEM electrolysis system can be challenging due to the fluctuation of renewable energies.This study introduces an approach integrating data with fundamental physics principles known as Physics-Informed Neural Networks(PINNs).This method solves differential equations and estimates the unknown parameters governing the temperature dynamics within the PEM electrolysis system.We consider two distinct scenarios:a zero-dimensional model and a one-dimensional model.The results demonstrate the PINN’s proficiency in accurately identifying the parameters and solving for temperature fluctuations within the system with different input conditions.Furthermore,we compare the PINN with the Long Short-Term Memory(LSTM)method to predict the outlet temperature of the electrolysis.The PINN outperformed the LSTM method,highlighting its reliability and precision,achieving a Mean Squared Error(MSE)of 0.1596 compared to 1.2132 for LSTM models.The proposed method shows a high performance in dealing with sensor noises and avoids overfitting problems.This synergy of physics knowledge and data-driven learning opens new pathways towards real-time digital twins,enhanced predictive control,and improved reliability for PEM electrolysis and other complex,data-scarce energy systems.
基金funded by the laboratoire Chrono-environnement and the OSU THETA^(⑰).
文摘Researchers often face difficulties in organizing and structuring their research data.Moreover,today,these data must respect the FAIR principles.To overcome these problems,in the environmental domain,the Meta-Obs project proposes a metamodel,a methodology and a tool that generates a”FAIRizable”database.The obtained database is adapted to the needs of the researcher and is enriched with metadata.In this article we present Meta-Obs and we illustrate its use with a concrete case:the design of the database of the Aspergillus fumigatus collection.
文摘The transition to sustainable and environmentally friendly energy sources is a crucial step in our global effort to reduce carbon emissions.In this context,fuel cell technology has emerged as a leading innovative solution,offering a promising alternative to conventional fossil fuel-based systems.It aims to achieve zero emissions while maintaining high efficiency and performance.Although fuel cell technology holds great potential for a sustainable and clean energy future,its widespread adoption is still hindered by several challenges.These include improving the efficiency and durability of fuel cells,as well as further enhancing their power output.To address these challenges,various design innovations and optimization strategies have been proposed to tackle the practical issues encountered in real-world applications.This special issue aims to provide a platform for researchers,engineers,and policymakers to present their latest scientific findings or engineering experiences in the development and application of new technologies to overcome the challenges in fuel cell application.
基金supported by the National Natural Science Foundation of China(No.U24A20263)the Engineering and Innovation through Physical Sciences,High-technologies,and Cross-disciplinary Research Graduate School(No.ANR-17-EURE-0002).
文摘In this paper,the synchronous rotor speed control problem of multiple permanent magnet synchronous motors(PMSMs)with port-Hamiltonian(PH)dynamics is investigated.First,the synchronous rotor speed problem is reformulated as an optimization problem and a distributed controller is proposed for each PMSM.Then,the stability of the closed-loop system is analyzed,and it is proven that its equilibrium aligns with the optimum of the value function derived from the optimization problem.Based on the proposed distributed controller,PMSMs exchange the estimated average rotor speed with their neighbours,rather than the direct rotor speed,which benefits the protection of the sensitive state variables.Finally,a simulation example is presented to validate the effectiveness of the proposed distributed controller.
基金supported by the National Natural Science Foundation of China(grant numbers 12072223,12122207,12021002,and 11991032)the EIPHI Graduate School(grant number ANR-17-EURE-0002).
文摘Impedance metasurfaces enable accurate regulation of acoustic fields.However,they can hardly supply a flexible response as such perfect operation is accompanied by stringent requirements on the design of unit cells.Actually,an arbitrary lossless and passive target impedance matrix requires the tuning of 3 independent real parameters.The set composed of a reflection phase,a transmission amplitude,and a transmission phase,enables the representation of an arbitrary impedance matrix,possibly possessing singular elements.In this paper,a mechanism of phase-amplitude-phase modulation(PAP modulation)is developed for the generic design of the unit cells of acoustic impedance metasurfaces.Adjustable acoustic impedance metasurfaces are further available under this framework.An impedance unit with 3 mobile parts is designed based on this idea.The assembled metasurface can handle different incidences for acoustic field manipulation at a given frequency.Beam steering and beam splitting are considered as demonstration examples and are verified by numerical simulation and experiment.PAP modulation enriches the design of acoustic impedance metasurfaces and extends the range of application of impedance theory.
文摘With the growing global energy demand and the pursuit of sustainable energy,solar energy has received widespread attention as a clean and renewable energy source.A structural design of an inflatable,large-scale solar concentrating reflector based on in-orbit assembly is proposed in this paper.The axisymmetric inflated reflector surface is inversely designed through membrane mechanics,and the internal pressures to maintain the reflector surface morphology at different orbital positions and the tiny deformation produced by the reflecting surface under the action of the uniform pressure are determined.A inflatable-rigidizable support structure is prepared by using a rigidizable aramid fabric-reinforced composite.The support structure used to the parabolic reflecting surface is designed,and the diameter and spacing distance of the resistance wire of the heating layer are determined by electrothermal simulation;the combination of solar radiation and electric heating is used to rigidize the reflector in orbit,and the corresponding electric heating time at different orbital positions is also analyzed by in orbit simulation.The heating voltage,folding radius and folding method of the rigidizable support structure are determined through the experimental design,and the folding and deployment experiments are carried out by using the heating and internal pressure and the final shape recovery rate of the support tube is approximately 100%,which verifies the feasibility of its folding and deployment.
文摘Thermal metamaterials represent a transformative paradigm in modern physics,synergizing thermodynamic principles with metamaterial engineering to master heat flow at will.As next-generation technologies demand multi-scale thermal control,this field urgently requires systematic frameworks to unify its multidisciplinary advances.Curated through a global collaboration involving over 50 specialists across 25 subdisciplines,this review primarily summarizes two decades of advancements,ranging from theoretical breakthroughs to functional implementations.The review reveals groundbreaking innovations in heat manipulation through the exploration of both classical and non-classical transport regimes,topological thermal control mechanisms,and quantum-informed phonon engineering strategies.By bridging physical insights like non-Hermitian thermal dynamics and valleytronic phonon transport with cutting-edge applications,we demonstrate paradigm-shifting capabilities:environment-adaptive thermal cloaks,AI-optimized metamaterials,and nonlinear thermal circuits enabling heat-based computation.Experimental milestones include 3D thermal null media with reconfigurable invisibility and thermal designs breaking classical conductivity limits.This collaborative effort establishes an indispensable roadmap for physicists,highlighting pathways to quantum thermal management,entropy-controlled energy systems,and topological devices.As thermal metamaterials transition from laboratory marvels to technological cornerstones,this work provides the foundational lexicon and design principles for the coming era of intelligent thermal matter.
基金supported in part by the National Natural Science Foundation(51977181,52077180)Natural Science Foundation of Sichuan Province(2022NSFSC0027)+2 种基金Fok Ying-Tong Education Foundation of China(171104)14th Five-year Major Science and Technology Research Project of CRRC(2021CXZ021-2)Key research and development project of China National Railway Group Co.,Ltd(N2022J016-B).
文摘A coordinated scheduling model based on two-stage distributionally robust optimization(TSDRO)is proposed for integrated energy systems(IESs)with electricity-hydrogen hybrid energy storage.The scheduling problem of the IES is divided into two stages in the TSDRO-based coordinated scheduling model.The first stage addresses the day-ahead optimal scheduling problem of the IES under deterministic forecasting information,while the sec-ond stage uses a distributionally robust optimization method to determine the intraday rescheduling problem under high-order uncertainties,building upon the results of the first stage.The scheduling model also considers col-laboration among the electricity,thermal,and gas networks,focusing on economic operation and carbon emissions.The flexibility of these networks and the energy gradient utilization of hydrogen units during operation are also incor-porated into the model.To improve computational efficiency,the nonlinear formulations in the TSDRO-based coordinated scheduling model are properly linearized to obtain a Mixed-Integer Linear Programming model.The Column-Constraint Generation(C&CG)algorithm is then employed to decompose the scheduling model into a mas-ter problem and subproblems.Through the iterative solution of the master problem and subproblems,an efficient analysis of the coordinated scheduling model is achieved.Finally,the effectiveness of the proposed TSDRO-based coordinated scheduling model is verified through case studies.The simulation results demonstrate that the proposed TSDRO-based coordinated scheduling model can effectively accomplish the optimal scheduling task while consider-ing the uncertainty and flexibility of the system.Compared with traditional methods,the proposed TSDRO-based coordinated scheduling model can better balance conservativeness and robustness.
文摘Femtosecond pulses from an ultrafast mode-locked fiber laser can be optimized in real time by combining single-shot spectral measurements with a smart genetic algorithm to actively control and drive the intracavity dynamics.
基金National Natural Science Foundation of China(NSFC)(61405075)Natural Science Foundation of Guangdong Province(2015A030306046)
文摘In this paper, we present an ultra-compact 1D photonic crystal(Ph C) Bragg grating design on a thin film lithium niobate slot waveguide(SWG) via 2D-and 3D-FDTD simulations. 2D-FDTD simulations are employed to tune the photonic bandgap(PBG) size, PBG center, cavity resonance wavelength, and the whole size of Ph C. 3DFDTD simulations are carried out to model the real structure by varying different geometrical parameters such as SWG height and Ph C size. A moderate resonance quality factor Q of about 300 is achieved with a Ph C size of only 0.5 μm× 0.7 μm× 6 μm. The proposed slot Bragg grating structure is then exploited as an electric field(E-field) sensor. The sensitivity is analyzed by 3D-FDTD simulations with a minimum detectable E-field as small as 23 m V∕m. The possible fabrication process of the proposed structure is also discussed. The compact size of the proposed slot Bragg grating structure may have applications in on-chip E-field sensing, optical filtering, etc.
文摘The Year 2020 represents 60 years since the first successful operation of the laser.This anniversary provides an ideal occasion to reflect on the myriad ways that lasers have revolutionized society,and to consider the many new areas of research that continue to drive photonics in unexpected directions.Yet at the same time as we consider these exciting future perspectives,it is also interesting to see how the development of the laser traces a path that intertwines basic and applied science,and intersects with the recognition of many of the pioneers of optics through the Nobel Prize.Of course,an exhaustive history of such a rich topic cannot be given in a short Perspective,but it is perhaps possible to describe some of the key highlights.
基金This work has been supported by the ANR DEAL(contract ANR-20-CE05-0016-01)This work has also been partially funded by Region Sud Provence-Alpes-Cote d’Azur via project AMULTI(2021_02918).
文摘In the paper,a novel self-learning energy management strategy(EMS)is proposed for fuel cell hybrid electric vehicles(FCHEV)to achieve the hydrogen saving and maintain the battery operation.In the EMS,it is proposed to approximate the EMS policy function with fuzzy inference system(FIS)and learn the policy parameters through policy gradient reinforcement learning(PGRL).Thus,a so-called Fuzzy REINFORCE algorithm is first proposed and studied for EMS problem in the paper.Fuzzy REINFORCE is a model-free method that the EMS agent can learn itself through interactions with environment,which makes it independent of model accuracy,prior knowledge,and expert experience.Meanwhile,to stabilize the training process,a fuzzy baseline function is adopted to approximate the value function based on FIS without affecting the policy gradient direction.More-over,the drawbacks of traditional reinforcement learning such as high computation burden,long convergence time,can also be overcome.The effectiveness of the proposed methods were verified by Hardware-in-Loop ex-periments.The adaptability of the proposed method to the changes of driving conditions and system states is also verified.
基金funded by NPRP grant no.NPRP10-0201-170315 from the Qatar National Research Fund(a member of Qatar Foundation)supported by the EIPHI Graduate School(contract“ANR-17-EURE-0002”)。
文摘Acoustic wave resonators are promising candidates for gravimetric biosensing.However,they generally suffer from strong acoustic radiation in liquid,which limits their quality factor and increases their frequency noise.This article presents an acoustic radiation-free gravimetric biosensor based on a locally resonant surface phononic crystal(SPC)consisting of periodic high aspect ratio electrodes to address the above issue.The acoustic wave generated in the SPC is slower than the sound wave in water,hence it prevents acoustic propagation in the fluid and results in energy confinement near the electrode surface.This energy confinement results in a significant quality factor improvement and reduces frequency noise.The proposed SPC resonator is numerically studied by finite element analysis and experimentally implemented by an electroplating-based fabrication process.Experimental results show that the SPC resonator exhibits an in-liquid quality factor 15 times higher than a conventional Rayleigh wave resonator at a similar operating frequency.The proposed radiation suppression method using SPC can also be applied in other types of acoustic wave resonators.Thus,this method can serve as a general technique for boosting the in-liquid quality factor and sensing performance of many acoustic biosensors.
