In this work,we developed a simple and direct circuit model with a dual two-diode model that can be solved by a SPICE numerical simulation to comprehensively describe the monolithic perovskite/crystalline silicon(PVS/...In this work,we developed a simple and direct circuit model with a dual two-diode model that can be solved by a SPICE numerical simulation to comprehensively describe the monolithic perovskite/crystalline silicon(PVS/c-Si)tandem solar cells.We are able to reveal the effects of different efficiency-loss mechanisms based on the illuminated current density-voltage(J-V),semi-log dark J-V,and local ideality factor(m-V)curves.The effects of the individual efficiency-loss mechanism on the tandem cell’s efficiency are discussed,including the exp(V/VT)and exp(V/2VT)recombination,the whole cell’s and subcell’s shunts,and the Ohmic-contact or Schottky-contact of the intermediate junction.We can also fit a practical J-V curve and find a specific group of parameters by the trial-and-error method.Although the fitted parameters are not a unique solution,they are valuable clues for identifying the efficiency loss with the aid of the cell’s structure and experimental processes.This method can also serve as an open platform for analyzing other tandem solar cells by substituting the corresponding circuit models.In summary,we developed a simple and effective methodology to diagnose the efficiency-loss source of a monolithic PVS/c-Si tandem cell,which is helpful to researchers who wish to adopt the proper approaches to improve their solar cells.展开更多
Solar stills are considered an effective method to solve the scarcity of drinkable water.However,it is still missing a way to forecast its production.Herein,it is proposed that a convenient forecasting model which jus...Solar stills are considered an effective method to solve the scarcity of drinkable water.However,it is still missing a way to forecast its production.Herein,it is proposed that a convenient forecasting model which just needs to input the conventional weather forecasting data.The model is established by using machine learning methods of random forest and optimized by Bayesian algorithm.The required data to train the model are obtained from daily measurements lasting9 months.To validate the accuracy model,the determination coefficients of two types of solar stills are calculated as 0.935and 0.929,respectively,which are much higher than the value of both multiple linear regression(0.767)and the traditional models(0.829 and 0.847).Moreover,by applying the model,we predicted the freshwater production of four cities in China.The predicted production is approved to be reliable by a high value of correlation(0.868)between the predicted production and the solar insolation.With the help of the forecasting model,it would greatly promote the global application of solar stills.展开更多
CrAlYN coatings with different Y contents(0,5 and 12 at.%)were deposited by cathodic arc evaporation to investigate the influence of Y-addition on the structure,mechanical and thermal properties of CrAlN coatings by u...CrAlYN coatings with different Y contents(0,5 and 12 at.%)were deposited by cathodic arc evaporation to investigate the influence of Y-addition on the structure,mechanical and thermal properties of CrAlN coatings by using X-ray diffraction,scanning electron microscopy,differential scanning calorimetry,thermal gravimetric analysis and nanoindentation.The structural transformation of single phase cubic Cr_(0.42)Al_(0.58)N and Cr_(0.39)Al_(0.56)Y_(0.05)N coatings to cubic−wurtzite mixed Cr_(0.32)Al_(0.56)Y_(0.12)N coating leads to a drop in hardness from(30.2±0.7)GPa of Cr_(0.42)Al_(0.58)N and(32.0±1.0)GPa of Cr_(0.39)Al_(0.56)Y_(0.05)N to(25.2±0.7)GPa of Cr_(0.32)Al_(0.56)Y_(0.12)N.The incorporation of 5 at.%Y retards the thermal decomposition of CrAlN,verified by the postponed precipitation of w-AlN and N-loss upon annealing.Correspondingly,Cr_(0.39)Al_(0.56)Y_(0.05)N coating consistently exhibits the highest hardness value during thermal annealing.Nevertheless,alloying with Y exerts an adverse effect on the oxidation resistance of CrAlN.展开更多
VAlN coating is of particular interest for dry cutting applications owing to its low-friction and excellent abrasiveness.Nano-multilayer structure is designed to tailor the properties of VAlN coating.In this work,a se...VAlN coating is of particular interest for dry cutting applications owing to its low-friction and excellent abrasiveness.Nano-multilayer structure is designed to tailor the properties of VAlN coating.In this work,a series of VAlN/Si_(3)N_(4) nano-multilayer coatings with varied Si_(3)N_(4) layer thicknesses were prepared by reactive sputtering method.The microstructure and mechanical properties of the coatings were both investigated.It is revealed that Si_(3)N_(4) with a shallow thickness(~0.4 nm)was crystallized and grown coherently with VAlN,showing a remarkable increase in hardness compared to VAlN monolayer coating.The hardness of coherently VAlN/Si_(3)N_(4) nano-multilayer coatings reached to 48.7 GPa.With further increase of Si_(3)N_(4) layer thickness,the coherent growth of nano-multilayers was terminated,showing amorphous structure formed in nano-multilayers and the hardness was declined.On the other hand,when Si_(3)N_(4) layer thickness was 0.4 nm,the friction coefficient of VAlN/Si_(3)N_(4) nano-multilayer coating was almost equal to that of VAlN monolayer coating,which was attributed to the crystallization of Si_(3)N_(4) and the produced coherent interfaces between VAlN and Si_(3)N_(4) for the hardening effect of nano-multilayer coatings.Upon further increase of Si_(3)N_(4) layer thickness,pronounced improvement of friction coefficient in VAlN/Si_(3)N_(4) nano-multilayer coating was observed.展开更多
Various graph representation learning models convert graph nodes into vectors using techniques like matrix factorization,random walk,and deep learning.However,choosing the right method for different tasks can be chall...Various graph representation learning models convert graph nodes into vectors using techniques like matrix factorization,random walk,and deep learning.However,choosing the right method for different tasks can be challenging.Communities within networks help reveal underlying structures and correlations.Investigating how different models preserve community properties is crucial for identifying the best graph representation for data analysis.This paper defines indicators to explore the perceptual quality of community properties in representation learning spaces,including the consistency of community structure,node distribution within and between communities,and central node distribution.A visualization system presents these indicators,allowing users to evaluate models based on community structures.Case studies demonstrate the effectiveness of the indicators for the visual evaluation of graph representation learning models.展开更多
Transfer learning is an effective method to predict the energy consumption of information-poor buildings by learning transferable knowledge from operational data of information-rich buildings.However,it is not recomme...Transfer learning is an effective method to predict the energy consumption of information-poor buildings by learning transferable knowledge from operational data of information-rich buildings.However,it is not recommended to directly use the operational data without protection due to the risk of leaking occupants’privacy.To address this problem,this study proposes a federated learning-based method to learn transferable knowledge from building operational data without privacy leaking.It trains a transferable federated model based on the operational data from the buildings similar to the target building with limited data.An advanced secure aggregation algorithm is adopted in the training process to ensure that no one can infer private information from the training data.The federated model obtained is evaluated by comparing it with the standalone model without federated learning based on 13 similar office buildings from the Building Data Genome Project.The results show that the federated model outperforms the standalone model concerning the prediction accuracy and training time.On average,the federated model achieves a 25.4%decrease in CV-RMSE when the target building has limited operational data.Even if the target building has no operational data,the federated model still achieves acceptable accuracy(CV-RMSE is 22.2%).Meanwhile,the training time of the federated model is 90%less than that of the standalone model.The research insights can help develop federated learning-based methods for solving the data silos problem in building energy management.The methodology and analysis procedures are reproducible and all codes and data sets are available on Github.展开更多
Probabilistic graphical models(PGMs)can effectively deal with the problems of energy consumption and occupancy prediction,fault detection and diagnosis,reliability analysis,and optimization in energy systems.Compared ...Probabilistic graphical models(PGMs)can effectively deal with the problems of energy consumption and occupancy prediction,fault detection and diagnosis,reliability analysis,and optimization in energy systems.Compared with the black-box models,PGMs show advantages in model interpretability,scalability and reliability.They have great potential to realize the true artificial intelligence in energy systems of the next generation.This paper intends to provide a comprehensive review of the PGM-based approaches published in the last decades.It reveals the advantages,limitations and potential future research directions of the PGM-based approaches for energy systems.Two types of PGMs are summarized in this review,including static models(SPGMs)and dynamic models(DPGMs).SPGMs can conduct probabilistic inference based on incomplete,uncertain or even conflicting information.SPGM-based approaches are proposed to deal with various management tasks in energy systems.They show outstanding performance in fault detection and diagnosis of energy systems.DPGMs can represent a dynamic and stochastic process by describing how its state changes with time.DPGM-based approaches have high accuracy in predicting the energy consumption,occupancy and failures of energy systems.In the future,a unified framework is suggested to fuse the knowledge-driven and data-driven PGMs for achieving better performances.Universal PGM-based approaches are needed that can be adapted to various energy systems.Hybrid algorithms would outperform the basic PGMs by integrating advanced techniques such as deep learning and first-order logic.展开更多
In this study, the promotion effect of H2 pretreatment on the SCR performance of CeO2 catalyst was investigated based on the characterization results of XRD, H2-TPR, Raman and in situ DRIFT techniques.Lower crystallin...In this study, the promotion effect of H2 pretreatment on the SCR performance of CeO2 catalyst was investigated based on the characterization results of XRD, H2-TPR, Raman and in situ DRIFT techniques.Lower crystallinity, higher reducibility and surface acidity can be found on CeO2-H catalyst. The results of DRIFT study reveal that the pretreatment of CeO2 catalyst with H2 can facilitate the adsorption of NH3 and NOx species, while the adsorbed NOx is basically inactive in the NH3-SCR reaction. Moreover, the reaction mechanism of the NH3-SCR reaction over CeO2 catalyst is not changed by H2 pretreatment,which is mainly under the control of Eley-Rideal（E-R） mechanism, The enhanced SCR performance of CeO2-H catalyst is mainly due to the promoted NH3 adsorption and the subsequent facilitation of SCR reaction through E-R pathway.展开更多
Conventional titanium oxide(TiO2) as an electron transport layer(ETL) in hybrid organic-inorganic perovskite solar cells(PSCs) requires a sintering process at a high temperature to crystalize, which is not suitable fo...Conventional titanium oxide(TiO2) as an electron transport layer(ETL) in hybrid organic-inorganic perovskite solar cells(PSCs) requires a sintering process at a high temperature to crystalize, which is not suitable for flexible PSCs and tandem solar cells with their low-temperatureprocessed bottom cell. Here, we introduce a low-temperature solution method to deposit a TiO2/tin oxide(SnO2) bilayer towards an efficient ETL. From the systematic measurements of optical and electronic properties, we demonstrate that the TiO2/SnO2 ETL has an enhanced charge extraction ability and a suppressed carrier recombination at the ETL/perovskite interface, both of which are beneficial to photo-generated carrier separation and transport. As a result, PSCs with TiO2/SnO2 bilayer ETLs present higher photovoltaic performance of the baseline cells compared with their TiO2 and SnO2 single-layer ETL counterparts. The champion PSC has a power conversion efficiency(PCE) of 19.11% with an open-circuit voltage(Voc)of 1.15 V, a short-circuit current density(Jsc) of 22.77 mA cm^-2,and a fill factor(FF) of 72.38%. Additionally, due to the suitable band alignment of the TiO2/SnO2 ETL in the device, a high Vocof 1.18 V is achieved. It has been proven that the TiO2/SnO2 bilayer is a promising alternative ETL for high efficiency PSCs.展开更多
Organic-inorganic metal-halide perovskite solar cells(PerSCs)have achieved significant progresses due to their outstanding optoelectronic charac-teristics,and the power conversion efficiency(PCE)of single-junction Per...Organic-inorganic metal-halide perovskite solar cells(PerSCs)have achieved significant progresses due to their outstanding optoelectronic charac-teristics,and the power conversion efficiency(PCE)of single-junction PerSCs has been boosted from 3.8%to a certified 25.2%.However,the efficien-cy of single-junction cells is governed by the Shockley-Queisser(S-Q)radiative limit,and fabricating all-perovskite tandem solar cells is a particularly attractive method to break the S-Q limit.Since the bandgap of lead(Pb)-based mixed halide perovskite can be tuned from 1.55 eV to 2.3 eV,and the mixed tin(Sn)-Pb perovskites have bandgap of~1.2 eV,these perovskites become the best candidates for the front and rear subcells of all-perovskite tandem device,respectively.In this review,we firstly summarize the current development progresses of two-terminal(2-T)all-perovskite tandem so-lar cells.For further optimizing the device performance,the wide bandgap mixed halide perovskites for front subcell,mixed Sn-Pb narrow bandgap perovskites for rear subcell,and the interconnection layer(ICL)of 2-T tandem device are then discussed.This review aims to open a pathway to real-ize highly efficient all-perovskite tandem solar cells.展开更多
Conductivity and oxidation behavior of Fe-16Cr alloy were investigated under long-term stability operation at 750℃and thermal cycles from room temperature to 750℃.The results showed that the area specific resistance...Conductivity and oxidation behavior of Fe-16Cr alloy were investigated under long-term stability operation at 750℃and thermal cycles from room temperature to 750℃.The results showed that the area specific resistance(ASR)of Fe-16Cr alloy increased over time and reached about 56.29 mΩcm~(2)after 40,000 h of long-term stability operation at 750℃by theoretical calculation.The ASR of Fe-16Cr remained about 11 mΩcm~(2)after 52 thermal cycles from room temperature to750℃.The analysis of structure showed that the oxidized phase on the surface of Fe-16Cr was mainly composed of Cr_(2)O_3and Fe Cr_(2)O_(4)spinel phase under long-term stability operation at 750℃.While the Cr_(2)O_(3)phase was mainly observed on the surface of Fe-16Cr alloy after 52 thermal cycles,the oxidation rates of Fe-16Cr alloy were 0.0142μm h~(-1)and 0.06μm cycle~(-1)under long-term stability operation and under thermal cycle,respectively.The property of Fe-16Cr alloy with 2.6 mm thickness met the lifespan requirement of interconnect for solid oxide fuel cell(SOFC)stacks.The Cr element all diff used onto oxidation surface,indicating that it was necessary to spray a coating on the surface to avoid poisoning cell cathode of SOFCs.Two 2-cell stacks were assembled and tested to verify the properties of Fe-16Cr alloy as SOFC interconnect under long-term stability operation and thermal cycle condition.展开更多
The transparent envelope structure has huge energy-saving potential, which is the key point to reduce building energy consumption and improve the thermal building environment. The solar radiation transmitted through t...The transparent envelope structure has huge energy-saving potential, which is the key point to reduce building energy consumption and improve the thermal building environment. The solar radiation transmitted through the transparent envelope structure(transmitted solar radiation) is reflected, scattered and absorbed by the indoor surface, which has a significant impact on the heat gain of the building. In this paper, firstly, the diffuse radiation received by different depths of various indoor surfaces is measured by experimental tests, and the distribution function of transmitted diffuse solar radiation(TDSR) on the indoor surface is established. Secondly, the diffuse solar radiation received by the indoor and outdoor surfaces in different seasons is continuously monitored;the variation of TDSR with time is analyzed, and the distribution function of TDSR on indoor surface with time is proposed. Finally, based on the temporal and spatial distribution characteristics of diffuse radiation under different weather conditions, the variation of TDSR with the weather is studied, and the distribution function of TDSR on the indoor surface with weather changes is established. The distribution function of the TDSR on the indoor surface under different depths, time and weather conditions obtained in this study can supplement and improve the theory of building heat gain and load, and help accurate simulation of building energy consumption.展开更多
Municipal Solid Waste(MSW)was converted into high-grade solid fuels(biochar)and gaseous product via thermal pyrolysis under pyrolytic gas atmosphere.The experiment was carried out in a packed-bed reactor at the temper...Municipal Solid Waste(MSW)was converted into high-grade solid fuels(biochar)and gaseous product via thermal pyrolysis under pyrolytic gas atmosphere.The experiment was carried out in a packed-bed reactor at the temperature range of 600-800℃ in both atmospheres of N_(2) and pyrolytic gas.Gas,liquid,and solid products were analyzed by gas chromatograph and elemental analysis.Amount of biochar obtained from both atmospheres were not significantly different.CH_(4) and CO_(2) in pyrolytic gas promoted the release of volatile in the MSW,resulting in lower ratio of VM/FC,ca.0.13.The atomic ratios of O/C and H/C were around 0.02-0.11 and 0.005-0.035,respectively.These values were equivalent to anthracite coal type.On the other hand,the liquid fuel yield under pyrolytic gas condition was found to be higher,compared with that under N_(2) condition.In addition,the enhancement of H_(2) and CO production was accompanied by the decrease in CH_(4) and CO_(2) output.Overall,the operating condition at 800℃ or higher with reaction times longer than 4 min were recommended for production of biochar with fuel qualities approaching anthracite coal.展开更多
基金This work was supported by Zhejiang Energy Group(znkj-2018-118)Key Research and Development Program of Zhejiang Province(2021C01006)+5 种基金Key Project of Zhejiang Province(2021C04009)Science and technology projects in Liaoning Province 2021(2021JH1/10400104)Ningbo“Innovation 2025”Major Project(2020Z098)National Key R&D Program of China(2018YFB1500403)National Natural Science Foundation of China(61974178,61874177,62004199)Youth Innovation Promotion Association(2018333).
文摘In this work,we developed a simple and direct circuit model with a dual two-diode model that can be solved by a SPICE numerical simulation to comprehensively describe the monolithic perovskite/crystalline silicon(PVS/c-Si)tandem solar cells.We are able to reveal the effects of different efficiency-loss mechanisms based on the illuminated current density-voltage(J-V),semi-log dark J-V,and local ideality factor(m-V)curves.The effects of the individual efficiency-loss mechanism on the tandem cell’s efficiency are discussed,including the exp(V/VT)and exp(V/2VT)recombination,the whole cell’s and subcell’s shunts,and the Ohmic-contact or Schottky-contact of the intermediate junction.We can also fit a practical J-V curve and find a specific group of parameters by the trial-and-error method.Although the fitted parameters are not a unique solution,they are valuable clues for identifying the efficiency loss with the aid of the cell’s structure and experimental processes.This method can also serve as an open platform for analyzing other tandem solar cells by substituting the corresponding circuit models.In summary,we developed a simple and effective methodology to diagnose the efficiency-loss source of a monolithic PVS/c-Si tandem cell,which is helpful to researchers who wish to adopt the proper approaches to improve their solar cells.
基金Project supported by the National Key Research and Development Program of China(Grant No.2018YFE0127800)the Science,Technology&Innovation Funding Authority(STIFA),Egypt grant(Grant No.40517)+1 种基金China Postdoctoral Science Foundation(Grant No.2020M682411)the Fundamental Research Funds for the Central Universities(Grant No.2019kfy RCPY045)。
文摘Solar stills are considered an effective method to solve the scarcity of drinkable water.However,it is still missing a way to forecast its production.Herein,it is proposed that a convenient forecasting model which just needs to input the conventional weather forecasting data.The model is established by using machine learning methods of random forest and optimized by Bayesian algorithm.The required data to train the model are obtained from daily measurements lasting9 months.To validate the accuracy model,the determination coefficients of two types of solar stills are calculated as 0.935and 0.929,respectively,which are much higher than the value of both multiple linear regression(0.767)and the traditional models(0.829 and 0.847).Moreover,by applying the model,we predicted the freshwater production of four cities in China.The predicted production is approved to be reliable by a high value of correlation(0.868)between the predicted production and the solar insolation.With the help of the forecasting model,it would greatly promote the global application of solar stills.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(No.51775560).
文摘CrAlYN coatings with different Y contents(0,5 and 12 at.%)were deposited by cathodic arc evaporation to investigate the influence of Y-addition on the structure,mechanical and thermal properties of CrAlN coatings by using X-ray diffraction,scanning electron microscopy,differential scanning calorimetry,thermal gravimetric analysis and nanoindentation.The structural transformation of single phase cubic Cr_(0.42)Al_(0.58)N and Cr_(0.39)Al_(0.56)Y_(0.05)N coatings to cubic−wurtzite mixed Cr_(0.32)Al_(0.56)Y_(0.12)N coating leads to a drop in hardness from(30.2±0.7)GPa of Cr_(0.42)Al_(0.58)N and(32.0±1.0)GPa of Cr_(0.39)Al_(0.56)Y_(0.05)N to(25.2±0.7)GPa of Cr_(0.32)Al_(0.56)Y_(0.12)N.The incorporation of 5 at.%Y retards the thermal decomposition of CrAlN,verified by the postponed precipitation of w-AlN and N-loss upon annealing.Correspondingly,Cr_(0.39)Al_(0.56)Y_(0.05)N coating consistently exhibits the highest hardness value during thermal annealing.Nevertheless,alloying with Y exerts an adverse effect on the oxidation resistance of CrAlN.
基金Project(51201187)supported by the National Natural Science Foundation of China。
文摘VAlN coating is of particular interest for dry cutting applications owing to its low-friction and excellent abrasiveness.Nano-multilayer structure is designed to tailor the properties of VAlN coating.In this work,a series of VAlN/Si_(3)N_(4) nano-multilayer coatings with varied Si_(3)N_(4) layer thicknesses were prepared by reactive sputtering method.The microstructure and mechanical properties of the coatings were both investigated.It is revealed that Si_(3)N_(4) with a shallow thickness(~0.4 nm)was crystallized and grown coherently with VAlN,showing a remarkable increase in hardness compared to VAlN monolayer coating.The hardness of coherently VAlN/Si_(3)N_(4) nano-multilayer coatings reached to 48.7 GPa.With further increase of Si_(3)N_(4) layer thickness,the coherent growth of nano-multilayers was terminated,showing amorphous structure formed in nano-multilayers and the hardness was declined.On the other hand,when Si_(3)N_(4) layer thickness was 0.4 nm,the friction coefficient of VAlN/Si_(3)N_(4) nano-multilayer coating was almost equal to that of VAlN monolayer coating,which was attributed to the crystallization of Si_(3)N_(4) and the produced coherent interfaces between VAlN and Si_(3)N_(4) for the hardening effect of nano-multilayer coatings.Upon further increase of Si_(3)N_(4) layer thickness,pronounced improvement of friction coefficient in VAlN/Si_(3)N_(4) nano-multilayer coating was observed.
文摘Various graph representation learning models convert graph nodes into vectors using techniques like matrix factorization,random walk,and deep learning.However,choosing the right method for different tasks can be challenging.Communities within networks help reveal underlying structures and correlations.Investigating how different models preserve community properties is crucial for identifying the best graph representation for data analysis.This paper defines indicators to explore the perceptual quality of community properties in representation learning spaces,including the consistency of community structure,node distribution within and between communities,and central node distribution.A visualization system presents these indicators,allowing users to evaluate models based on community structures.Case studies demonstrate the effectiveness of the indicators for the visual evaluation of graph representation learning models.
基金supported by the National Key Research and Development Program of China(No.2018YFE0116300)the National Natural Science Foundation of China(No.51978601).
文摘Transfer learning is an effective method to predict the energy consumption of information-poor buildings by learning transferable knowledge from operational data of information-rich buildings.However,it is not recommended to directly use the operational data without protection due to the risk of leaking occupants’privacy.To address this problem,this study proposes a federated learning-based method to learn transferable knowledge from building operational data without privacy leaking.It trains a transferable federated model based on the operational data from the buildings similar to the target building with limited data.An advanced secure aggregation algorithm is adopted in the training process to ensure that no one can infer private information from the training data.The federated model obtained is evaluated by comparing it with the standalone model without federated learning based on 13 similar office buildings from the Building Data Genome Project.The results show that the federated model outperforms the standalone model concerning the prediction accuracy and training time.On average,the federated model achieves a 25.4%decrease in CV-RMSE when the target building has limited operational data.Even if the target building has no operational data,the federated model still achieves acceptable accuracy(CV-RMSE is 22.2%).Meanwhile,the training time of the federated model is 90%less than that of the standalone model.The research insights can help develop federated learning-based methods for solving the data silos problem in building energy management.The methodology and analysis procedures are reproducible and all codes and data sets are available on Github.
基金supported by the National Key Research and Development Program of China(No.2018YFE0116300)the National Natural Science Foundation of China(No.51978601).
文摘Probabilistic graphical models(PGMs)can effectively deal with the problems of energy consumption and occupancy prediction,fault detection and diagnosis,reliability analysis,and optimization in energy systems.Compared with the black-box models,PGMs show advantages in model interpretability,scalability and reliability.They have great potential to realize the true artificial intelligence in energy systems of the next generation.This paper intends to provide a comprehensive review of the PGM-based approaches published in the last decades.It reveals the advantages,limitations and potential future research directions of the PGM-based approaches for energy systems.Two types of PGMs are summarized in this review,including static models(SPGMs)and dynamic models(DPGMs).SPGMs can conduct probabilistic inference based on incomplete,uncertain or even conflicting information.SPGM-based approaches are proposed to deal with various management tasks in energy systems.They show outstanding performance in fault detection and diagnosis of energy systems.DPGMs can represent a dynamic and stochastic process by describing how its state changes with time.DPGM-based approaches have high accuracy in predicting the energy consumption,occupancy and failures of energy systems.In the future,a unified framework is suggested to fuse the knowledge-driven and data-driven PGMs for achieving better performances.Universal PGM-based approaches are needed that can be adapted to various energy systems.Hybrid algorithms would outperform the basic PGMs by integrating advanced techniques such as deep learning and first-order logic.
基金supported by National Natural Science Foundation of China(21546014)the National Natural Science Foundation of Shanghai,China(14ZR1417800)
文摘In this study, the promotion effect of H2 pretreatment on the SCR performance of CeO2 catalyst was investigated based on the characterization results of XRD, H2-TPR, Raman and in situ DRIFT techniques.Lower crystallinity, higher reducibility and surface acidity can be found on CeO2-H catalyst. The results of DRIFT study reveal that the pretreatment of CeO2 catalyst with H2 can facilitate the adsorption of NH3 and NOx species, while the adsorbed NOx is basically inactive in the NH3-SCR reaction. Moreover, the reaction mechanism of the NH3-SCR reaction over CeO2 catalyst is not changed by H2 pretreatment,which is mainly under the control of Eley-Rideal（E-R） mechanism, The enhanced SCR performance of CeO2-H catalyst is mainly due to the promoted NH3 adsorption and the subsequent facilitation of SCR reaction through E-R pathway.
基金supported by the National Key Research and Development of China (2018YFB1500103 and 2018YFB0704100)the National Natural Science Foundation of China (61574145, 61874177, 51502315 and 61704176)+1 种基金Zhejiang Provincial Natural Science Foundation (LR16F040002)Zhejiang Energy Group (znkj-2018-118)
文摘Conventional titanium oxide(TiO2) as an electron transport layer(ETL) in hybrid organic-inorganic perovskite solar cells(PSCs) requires a sintering process at a high temperature to crystalize, which is not suitable for flexible PSCs and tandem solar cells with their low-temperatureprocessed bottom cell. Here, we introduce a low-temperature solution method to deposit a TiO2/tin oxide(SnO2) bilayer towards an efficient ETL. From the systematic measurements of optical and electronic properties, we demonstrate that the TiO2/SnO2 ETL has an enhanced charge extraction ability and a suppressed carrier recombination at the ETL/perovskite interface, both of which are beneficial to photo-generated carrier separation and transport. As a result, PSCs with TiO2/SnO2 bilayer ETLs present higher photovoltaic performance of the baseline cells compared with their TiO2 and SnO2 single-layer ETL counterparts. The champion PSC has a power conversion efficiency(PCE) of 19.11% with an open-circuit voltage(Voc)of 1.15 V, a short-circuit current density(Jsc) of 22.77 mA cm^-2,and a fill factor(FF) of 72.38%. Additionally, due to the suitable band alignment of the TiO2/SnO2 ETL in the device, a high Vocof 1.18 V is achieved. It has been proven that the TiO2/SnO2 bilayer is a promising alternative ETL for high efficiency PSCs.
基金supported by the National Natural Science Foundation of China(Nos.51873007,21835006,51961165102,51772218)the Open Project of Key Laboratory of Solar Energy Utilization&Energy Saving Technology of Zhejiang Province(ZJS-OP-2020-04)the State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources(Grant No.LAPS20003).
文摘Organic-inorganic metal-halide perovskite solar cells(PerSCs)have achieved significant progresses due to their outstanding optoelectronic charac-teristics,and the power conversion efficiency(PCE)of single-junction PerSCs has been boosted from 3.8%to a certified 25.2%.However,the efficien-cy of single-junction cells is governed by the Shockley-Queisser(S-Q)radiative limit,and fabricating all-perovskite tandem solar cells is a particularly attractive method to break the S-Q limit.Since the bandgap of lead(Pb)-based mixed halide perovskite can be tuned from 1.55 eV to 2.3 eV,and the mixed tin(Sn)-Pb perovskites have bandgap of~1.2 eV,these perovskites become the best candidates for the front and rear subcells of all-perovskite tandem device,respectively.In this review,we firstly summarize the current development progresses of two-terminal(2-T)all-perovskite tandem so-lar cells.For further optimizing the device performance,the wide bandgap mixed halide perovskites for front subcell,mixed Sn-Pb narrow bandgap perovskites for rear subcell,and the interconnection layer(ICL)of 2-T tandem device are then discussed.This review aims to open a pathway to real-ize highly efficient all-perovskite tandem solar cells.
基金financially supported by the Key R&D Program from the Ministry of Science and Technology of China(No.2018YFB1502600)the Ningbo Major Special Projects of the Plan“Science and Technology Innovation 2025”(No.2019B10043)+1 种基金the Science and Technology Project of Zhejiang Energy Group Co.,Ltd.(No.znkj-2018-008)the Key Laboratory of Solar Energy Utilization&Energy Saving Technology of Zhejiang Province。
文摘Conductivity and oxidation behavior of Fe-16Cr alloy were investigated under long-term stability operation at 750℃and thermal cycles from room temperature to 750℃.The results showed that the area specific resistance(ASR)of Fe-16Cr alloy increased over time and reached about 56.29 mΩcm~(2)after 40,000 h of long-term stability operation at 750℃by theoretical calculation.The ASR of Fe-16Cr remained about 11 mΩcm~(2)after 52 thermal cycles from room temperature to750℃.The analysis of structure showed that the oxidized phase on the surface of Fe-16Cr was mainly composed of Cr_(2)O_3and Fe Cr_(2)O_(4)spinel phase under long-term stability operation at 750℃.While the Cr_(2)O_(3)phase was mainly observed on the surface of Fe-16Cr alloy after 52 thermal cycles,the oxidation rates of Fe-16Cr alloy were 0.0142μm h~(-1)and 0.06μm cycle~(-1)under long-term stability operation and under thermal cycle,respectively.The property of Fe-16Cr alloy with 2.6 mm thickness met the lifespan requirement of interconnect for solid oxide fuel cell(SOFC)stacks.The Cr element all diff used onto oxidation surface,indicating that it was necessary to spray a coating on the surface to avoid poisoning cell cathode of SOFCs.Two 2-cell stacks were assembled and tested to verify the properties of Fe-16Cr alloy as SOFC interconnect under long-term stability operation and thermal cycle condition.
基金support of the National Natural Science Foundation of China(Grant No52178083)Open Project of Key Laboratory of Solar Energy Utilization&Energy Saving Technology of Zhejiang Province(Grant No.JSYJY-KJWZ-2021-011)。
文摘The transparent envelope structure has huge energy-saving potential, which is the key point to reduce building energy consumption and improve the thermal building environment. The solar radiation transmitted through the transparent envelope structure(transmitted solar radiation) is reflected, scattered and absorbed by the indoor surface, which has a significant impact on the heat gain of the building. In this paper, firstly, the diffuse radiation received by different depths of various indoor surfaces is measured by experimental tests, and the distribution function of transmitted diffuse solar radiation(TDSR) on the indoor surface is established. Secondly, the diffuse solar radiation received by the indoor and outdoor surfaces in different seasons is continuously monitored;the variation of TDSR with time is analyzed, and the distribution function of TDSR on indoor surface with time is proposed. Finally, based on the temporal and spatial distribution characteristics of diffuse radiation under different weather conditions, the variation of TDSR with the weather is studied, and the distribution function of TDSR on the indoor surface with weather changes is established. The distribution function of the TDSR on the indoor surface under different depths, time and weather conditions obtained in this study can supplement and improve the theory of building heat gain and load, and help accurate simulation of building energy consumption.
基金support of the National-International Cooperation Project(2016YFE0202000 and 2017YFE0107600)Zhejiang Natural Science Foundation Project(LY 17E060005).
文摘Municipal Solid Waste(MSW)was converted into high-grade solid fuels(biochar)and gaseous product via thermal pyrolysis under pyrolytic gas atmosphere.The experiment was carried out in a packed-bed reactor at the temperature range of 600-800℃ in both atmospheres of N_(2) and pyrolytic gas.Gas,liquid,and solid products were analyzed by gas chromatograph and elemental analysis.Amount of biochar obtained from both atmospheres were not significantly different.CH_(4) and CO_(2) in pyrolytic gas promoted the release of volatile in the MSW,resulting in lower ratio of VM/FC,ca.0.13.The atomic ratios of O/C and H/C were around 0.02-0.11 and 0.005-0.035,respectively.These values were equivalent to anthracite coal type.On the other hand,the liquid fuel yield under pyrolytic gas condition was found to be higher,compared with that under N_(2) condition.In addition,the enhancement of H_(2) and CO production was accompanied by the decrease in CH_(4) and CO_(2) output.Overall,the operating condition at 800℃ or higher with reaction times longer than 4 min were recommended for production of biochar with fuel qualities approaching anthracite coal.
