The primary objective of this study is to develop an innovative theoretical model to accurately predict the thermophysicalproperties of hybrid nanofluids designed to enhance cooling in solar panel applications.This re...The primary objective of this study is to develop an innovative theoretical model to accurately predict the thermophysicalproperties of hybrid nanofluids designed to enhance cooling in solar panel applications.This researchlays the groundwork for our future studies,which will focus on photovoltaic thermal applications.These nanofluidsconsist of water and nanoparticles of alumina(Al_(2)O_(3)),titanium dioxide(TiO_(2)),and copper(Cu),exploringvolumetric concentrations ranging from 0%to 4%for each type of nanoparticle,and up to 10%for total mixtures.The developed model accounts for complex interactions between the nanoparticles and the base fluid,as well assynergistic effects resulting from the coexistence of different nanoparticles.Detailed simulations have shownexceptional agreement with experimental results,reinforcing the credibility of our approach in accurately capturingthe thermophysical behavior of these hybrid nanofluids.Based on these results,our study proposes significantadvancements in the design and optimization of nanofluids for cooling applications in solar panels.These developmentsare crucial for improving the efficiency of solar installations by mitigating overheating effects,providinga solid foundation for practical applications in this rapidly evolving field.展开更多
Photovoltaic(PV)power forecasting is essential for balancing energy supply and demand in renewable energy systems.However,the performance of PV panels varies across different technologies due to differences in efficie...Photovoltaic(PV)power forecasting is essential for balancing energy supply and demand in renewable energy systems.However,the performance of PV panels varies across different technologies due to differences in efficiency and how they process solar radiation.This study evaluates the effectiveness of deep learning models in predicting PV power generation for three panel technologies:Hybrid-Si,Mono-Si,and Poly-Si,across three forecasting horizons:1-step,12-step,and 24-step.Among the tested models,the Convolutional Neural Network—Long Short-Term Memory(CNN-LSTM)architecture exhibited superior performance,particularly for the 24-step horizon,achieving R^(2)=0.9793 and MAE 0.0162 for the Poly-Si array,followed by Mono-Si(R^(2)=0.9768)and Hybrid-Si arrays(R^(2)=0.9769).These findings demonstrate that the CNN-LSTM model can provide accurate and reliable PV power predictions for all studied technologies.By identifying the most suitable predictive model for each panel technology,this study contributes to optimizing PV power forecasting and improving energy management strategies.展开更多
In this paper,experimental and numerical studies of heat transfer in a test local of side H=0.8 m heated from below are presented and compared.All the walls,the rest of the floor and the ceiling are made from plywood ...In this paper,experimental and numerical studies of heat transfer in a test local of side H=0.8 m heated from below are presented and compared.All the walls,the rest of the floor and the ceiling are made from plywood and polystyrene in sandwich form(3 mmplywood-3 cm polystyrene-3 mmplywood)just on one of the vertical walls contained a glazed door(2 H/3×0.15 m).This local is heated during two heating cycles by a square plate of iron the width L=0.6 H,which represents the heat source,its temperature T_(h) is controlled.The plate is heated for two cycles by an adjustable set-point heat source placed just down the center of it.For each cycle,the heat source is switched“on”for 6 h and switched“off”for 6 h.The outdoor air temperature is kept constant at a low temperature T_(c)<T_(h).All measurements are carried out with k-type thermocouples and with flux meters.Results will be qualitatively presented for two cycles of heating in terms of temperatures and heat flux densitiesϕfor various positions of the test local.The temperature evolution of the center and the profile of the temperature along the vertical centerline are compared by two dimensions simulation using the lattice Boltzmann method.The comparison shows a good agreement with a difference that does not exceed±1℃.展开更多
To realize carbon neutrality,there is an urgent need to develop sustainable,green energy systems(especially solar energy systems)owing to the environmental friendliness of solar energy,given the substantial greenhouse...To realize carbon neutrality,there is an urgent need to develop sustainable,green energy systems(especially solar energy systems)owing to the environmental friendliness of solar energy,given the substantial greenhouse gas emissions from fossil fuel-based power sources.When it comes to the evolution of intelligent green energy systems,Internet of Things(IoT)-based green-smart photovoltaic(PV)systems have been brought into the spotlight owing to their cutting-edge sensing and data-processing technologies.This review is focused on three critical segments of IoT-based green-smart PV systems.First,the climatic parameters and sensing technologies for IoT-based PV systems under extreme weather conditions are presented.Second,the methods for processing data from smart sensors are discussed,in order to realize health monitoring of PV systems under extreme environmental conditions.Third,the smart materials applied to sensors and the insulation materials used in PV backsheets are susceptible to aging,and these materials and their aging phenomena are highlighted in this review.This review also offers new perspectives for optimizing the current international standards for green energy systems using big data from IoT-based smart sensors.展开更多
This work details the development of a broad-spectrum LNA (Low Noise Amplifier) circuit using a 65 nm CMOS technology. The design incorporates an inductive degeneracy circuit, employing a theoretical approach to enhan...This work details the development of a broad-spectrum LNA (Low Noise Amplifier) circuit using a 65 nm CMOS technology. The design incorporates an inductive degeneracy circuit, employing a theoretical approach to enhance gain, minimize noise levels, and uphold low power consumption. The progression includes a shift to a cascode structure to further refine LNA parameters. Ultimately, with a 1.8 V bias, the achieved performance showcases a gain-to-noise figure ratio of 16 dB/0.5 dB, an IIP3 linearity at 5.1 dBm, and a power consumption of 3 mW. This architecture is adept at operating across a wide frequency band spanning from 0.5 GHz to 6 GHz, rendering it applicable in diverse RF scenarios.展开更多
This work presents a simulation of the phenomena of natural convection in an enclosure with a variable heating regime by the lattice Boltzmann method(LBM).We consider a square enclosure of side H filled with air(Pr=0....This work presents a simulation of the phenomena of natural convection in an enclosure with a variable heating regime by the lattice Boltzmann method(LBM).We consider a square enclosure of side H filled with air(Pr=0.71)and heated from below,with a hot portion of length L=0.8 H,by imposing a sinusoidal temperature.The unheated segments of the bottom wall are treated as adiabatic,and one of the vertical walls features a cold region,while the remaining walls remain adiabatic.The outcomes of the two-dimensional(2D)problem are depicted through isotherms,streamlines,the temperature evolution within the enclosure,and the Nusselt number.These visualizations span various amplitude values“a”in the interval[0.2,0.8],and of the period T0 for Ra=107.The amplitude and period effect on the results is evaluated and discussed.The amplitude of the temperature at the heart of the enclosure increases with the increase in amplitude.This also increases with the period(T0)of the imposed temperature,something that is not observable on the global Nusselt number.展开更多
In this paper, we present a study of thermal, average power scaling, change in index of refraction and stress in photonic crystal fiber lasers with different pump schemes: forward pump scheme, backward pump scheme, fo...In this paper, we present a study of thermal, average power scaling, change in index of refraction and stress in photonic crystal fiber lasers with different pump schemes: forward pump scheme, backward pump scheme, forward pump scheme with reflection of 98%, backward pump scheme with reflection of 98% and bi-directional pump scheme. We show that management of thermal effects in fiber lasers will determine the efficiency and success of scaling-up efforts. In addition, we show that the most suitable scheme is the bi-directional.展开更多
One of the difficulties encountered in the study of dusty plasmas is related to the knowledge of the size of the dust particles present. A variety of sources, physical and chemical mechanisms of formation, causes a wi...One of the difficulties encountered in the study of dusty plasmas is related to the knowledge of the size of the dust particles present. A variety of sources, physical and chemical mechanisms of formation, causes a wide variety of sizes and morphologies of dust. The diameter of a dust will not be unique but spread over several orders of magnitude. Its distribution in number, surface, mass or volume is called distribution. It is important to know this distribution in particle size because it strongly impacts the physical and radiative processes. To have a dust distribution in situ is very difficult;the reverse method can identify the particle populations from light extinction measures. In this study, we present an inversion procedure with a Tikhonov regularization dedicated to the determination of volume size distribution (V-PSD) from extinction measurements corresponding to the different wavelengths obtained by the Extinction Spectrometry technique.展开更多
In this article,we discuss the approach to solving a nonlinear PDE equation,specifically the p-Laplacian equation,with a general(nonlinear)boundary condition.We establish the existence and uniqueness of the solution,s...In this article,we discuss the approach to solving a nonlinear PDE equation,specifically the p-Laplacian equation,with a general(nonlinear)boundary condition.We establish the existence and uniqueness of the solution,subject to certain assumptions outlined in this paper.To solve our nonlinear problem using the Finite Element Method(FEM),we derive an appropriate variational formulation.Additionally,we introduce a study of the residual a posteriori-error indicator,establishing both upper and lower bounds to control the error.The upper bound is determined using averaging interpolators in some quasi-norms defined by Barrett and Liu.Furthermore,we prove the equivalence between the residual error and the true error e=u−u_(h).Lastly,we perform a simulation of the p-Laplacian problem in the L-shape domain using a Matlab program in two-dimensional space.展开更多
Floating photovoltaic(FPV)technology is emerging as a highly promising approach to accelerate decarbonization of the global economy,due to its higher power generation efficiency and lower land occupation.With the rapi...Floating photovoltaic(FPV)technology is emerging as a highly promising approach to accelerate decarbonization of the global economy,due to its higher power generation efficiency and lower land occupation.With the rapid development of FPV technology,the mechanical performance degradation of key components caused by the harsh marine environment has become a pressing issue,as it significantly contributes to failure behavior observed in FPV systems.A comprehensive compilation of the mechanical performance of key components in FPV systems is also currently unavailable.Here,the mechanical behavior of each structural component in FPV systems under harsh marine environments is systematically reviewed.It further emphasizes the synergistic effects of mechanical performance degradation among different components on the overall system.The drop-off rate(v)of normalized elongation at break(EAB)of polymer under the synergistic effect of various environmental factors increases from 7.5×10^(−4)h^(−1)to 21.8×10^(−4)h^(−1)compared with the single environmental stress.Moreover,the development of novel materials and innovative mechanical structures applied in FPV systems to enhance mechanical performance is discussed.The novel flexible PV modules applied in FPV systems minimize the loads acting on the mooring lines by 80%and increase power generation by 5%.Notably,this paper provides a theoretical foundation for developing standards of FPV systems,especially the establishment of standards related to the synergistic effects of the mechanical performance degradation of different key components on FPV systems.展开更多
文摘The primary objective of this study is to develop an innovative theoretical model to accurately predict the thermophysicalproperties of hybrid nanofluids designed to enhance cooling in solar panel applications.This researchlays the groundwork for our future studies,which will focus on photovoltaic thermal applications.These nanofluidsconsist of water and nanoparticles of alumina(Al_(2)O_(3)),titanium dioxide(TiO_(2)),and copper(Cu),exploringvolumetric concentrations ranging from 0%to 4%for each type of nanoparticle,and up to 10%for total mixtures.The developed model accounts for complex interactions between the nanoparticles and the base fluid,as well assynergistic effects resulting from the coexistence of different nanoparticles.Detailed simulations have shownexceptional agreement with experimental results,reinforcing the credibility of our approach in accurately capturingthe thermophysical behavior of these hybrid nanofluids.Based on these results,our study proposes significantadvancements in the design and optimization of nanofluids for cooling applications in solar panels.These developmentsare crucial for improving the efficiency of solar installations by mitigating overheating effects,providinga solid foundation for practical applications in this rapidly evolving field.
文摘Photovoltaic(PV)power forecasting is essential for balancing energy supply and demand in renewable energy systems.However,the performance of PV panels varies across different technologies due to differences in efficiency and how they process solar radiation.This study evaluates the effectiveness of deep learning models in predicting PV power generation for three panel technologies:Hybrid-Si,Mono-Si,and Poly-Si,across three forecasting horizons:1-step,12-step,and 24-step.Among the tested models,the Convolutional Neural Network—Long Short-Term Memory(CNN-LSTM)architecture exhibited superior performance,particularly for the 24-step horizon,achieving R^(2)=0.9793 and MAE 0.0162 for the Poly-Si array,followed by Mono-Si(R^(2)=0.9768)and Hybrid-Si arrays(R^(2)=0.9769).These findings demonstrate that the CNN-LSTM model can provide accurate and reliable PV power predictions for all studied technologies.By identifying the most suitable predictive model for each panel technology,this study contributes to optimizing PV power forecasting and improving energy management strategies.
文摘In this paper,experimental and numerical studies of heat transfer in a test local of side H=0.8 m heated from below are presented and compared.All the walls,the rest of the floor and the ceiling are made from plywood and polystyrene in sandwich form(3 mmplywood-3 cm polystyrene-3 mmplywood)just on one of the vertical walls contained a glazed door(2 H/3×0.15 m).This local is heated during two heating cycles by a square plate of iron the width L=0.6 H,which represents the heat source,its temperature T_(h) is controlled.The plate is heated for two cycles by an adjustable set-point heat source placed just down the center of it.For each cycle,the heat source is switched“on”for 6 h and switched“off”for 6 h.The outdoor air temperature is kept constant at a low temperature T_(c)<T_(h).All measurements are carried out with k-type thermocouples and with flux meters.Results will be qualitatively presented for two cycles of heating in terms of temperatures and heat flux densitiesϕfor various positions of the test local.The temperature evolution of the center and the profile of the temperature along the vertical centerline are compared by two dimensions simulation using the lattice Boltzmann method.The comparison shows a good agreement with a difference that does not exceed±1℃.
基金National Key R&D Program of China(Grant No.2023YFE0114600)The National Natural Science Foundation of China(NSFC)-(Grant No.52477029)+1 种基金Joint Laboratory of China-Morocco Green Energy and Advanced Materials,The Youth Innovation Team of Shaanxi Universities,The Xi’an City Science and Technology Project(No.23GXFW0070)Xi’an International Science and Technology Cooperation Base.
文摘To realize carbon neutrality,there is an urgent need to develop sustainable,green energy systems(especially solar energy systems)owing to the environmental friendliness of solar energy,given the substantial greenhouse gas emissions from fossil fuel-based power sources.When it comes to the evolution of intelligent green energy systems,Internet of Things(IoT)-based green-smart photovoltaic(PV)systems have been brought into the spotlight owing to their cutting-edge sensing and data-processing technologies.This review is focused on three critical segments of IoT-based green-smart PV systems.First,the climatic parameters and sensing technologies for IoT-based PV systems under extreme weather conditions are presented.Second,the methods for processing data from smart sensors are discussed,in order to realize health monitoring of PV systems under extreme environmental conditions.Third,the smart materials applied to sensors and the insulation materials used in PV backsheets are susceptible to aging,and these materials and their aging phenomena are highlighted in this review.This review also offers new perspectives for optimizing the current international standards for green energy systems using big data from IoT-based smart sensors.
文摘This work details the development of a broad-spectrum LNA (Low Noise Amplifier) circuit using a 65 nm CMOS technology. The design incorporates an inductive degeneracy circuit, employing a theoretical approach to enhance gain, minimize noise levels, and uphold low power consumption. The progression includes a shift to a cascode structure to further refine LNA parameters. Ultimately, with a 1.8 V bias, the achieved performance showcases a gain-to-noise figure ratio of 16 dB/0.5 dB, an IIP3 linearity at 5.1 dBm, and a power consumption of 3 mW. This architecture is adept at operating across a wide frequency band spanning from 0.5 GHz to 6 GHz, rendering it applicable in diverse RF scenarios.
文摘This work presents a simulation of the phenomena of natural convection in an enclosure with a variable heating regime by the lattice Boltzmann method(LBM).We consider a square enclosure of side H filled with air(Pr=0.71)and heated from below,with a hot portion of length L=0.8 H,by imposing a sinusoidal temperature.The unheated segments of the bottom wall are treated as adiabatic,and one of the vertical walls features a cold region,while the remaining walls remain adiabatic.The outcomes of the two-dimensional(2D)problem are depicted through isotherms,streamlines,the temperature evolution within the enclosure,and the Nusselt number.These visualizations span various amplitude values“a”in the interval[0.2,0.8],and of the period T0 for Ra=107.The amplitude and period effect on the results is evaluated and discussed.The amplitude of the temperature at the heart of the enclosure increases with the increase in amplitude.This also increases with the period(T0)of the imposed temperature,something that is not observable on the global Nusselt number.
文摘In this paper, we present a study of thermal, average power scaling, change in index of refraction and stress in photonic crystal fiber lasers with different pump schemes: forward pump scheme, backward pump scheme, forward pump scheme with reflection of 98%, backward pump scheme with reflection of 98% and bi-directional pump scheme. We show that management of thermal effects in fiber lasers will determine the efficiency and success of scaling-up efforts. In addition, we show that the most suitable scheme is the bi-directional.
文摘One of the difficulties encountered in the study of dusty plasmas is related to the knowledge of the size of the dust particles present. A variety of sources, physical and chemical mechanisms of formation, causes a wide variety of sizes and morphologies of dust. The diameter of a dust will not be unique but spread over several orders of magnitude. Its distribution in number, surface, mass or volume is called distribution. It is important to know this distribution in particle size because it strongly impacts the physical and radiative processes. To have a dust distribution in situ is very difficult;the reverse method can identify the particle populations from light extinction measures. In this study, we present an inversion procedure with a Tikhonov regularization dedicated to the determination of volume size distribution (V-PSD) from extinction measurements corresponding to the different wavelengths obtained by the Extinction Spectrometry technique.
文摘In this article,we discuss the approach to solving a nonlinear PDE equation,specifically the p-Laplacian equation,with a general(nonlinear)boundary condition.We establish the existence and uniqueness of the solution,subject to certain assumptions outlined in this paper.To solve our nonlinear problem using the Finite Element Method(FEM),we derive an appropriate variational formulation.Additionally,we introduce a study of the residual a posteriori-error indicator,establishing both upper and lower bounds to control the error.The upper bound is determined using averaging interpolators in some quasi-norms defined by Barrett and Liu.Furthermore,we prove the equivalence between the residual error and the true error e=u−u_(h).Lastly,we perform a simulation of the p-Laplacian problem in the L-shape domain using a Matlab program in two-dimensional space.
基金supported by the National Key R&D Pro-gram of China(Grant No.2023YFE0114600)The National Natural Science Foundation of China(NSFC)(Grant No.52477029)Joint Laboratory of China-Morocco Green Energy and Advanced Materials,The Youth Innovation Team of Shaanxi Universities and The Xi’an City Science and Technology Project(No.23GXFW0070)。
文摘Floating photovoltaic(FPV)technology is emerging as a highly promising approach to accelerate decarbonization of the global economy,due to its higher power generation efficiency and lower land occupation.With the rapid development of FPV technology,the mechanical performance degradation of key components caused by the harsh marine environment has become a pressing issue,as it significantly contributes to failure behavior observed in FPV systems.A comprehensive compilation of the mechanical performance of key components in FPV systems is also currently unavailable.Here,the mechanical behavior of each structural component in FPV systems under harsh marine environments is systematically reviewed.It further emphasizes the synergistic effects of mechanical performance degradation among different components on the overall system.The drop-off rate(v)of normalized elongation at break(EAB)of polymer under the synergistic effect of various environmental factors increases from 7.5×10^(−4)h^(−1)to 21.8×10^(−4)h^(−1)compared with the single environmental stress.Moreover,the development of novel materials and innovative mechanical structures applied in FPV systems to enhance mechanical performance is discussed.The novel flexible PV modules applied in FPV systems minimize the loads acting on the mooring lines by 80%and increase power generation by 5%.Notably,this paper provides a theoretical foundation for developing standards of FPV systems,especially the establishment of standards related to the synergistic effects of the mechanical performance degradation of different key components on FPV systems.
