High-entropy borides(HEBs)are unable to serve in environments above 1800℃because of their poor oxidation resistance,which severely limits the application of these materials in ultra-high temperature environments.To s...High-entropy borides(HEBs)are unable to serve in environments above 1800℃because of their poor oxidation resistance,which severely limits the application of these materials in ultra-high temperature environments.To solve this problem,a series of HEBs with different ratios of metal elements were designed and prepared in this work,and their oxidation behavior above 1800℃was investigated.The results showed that non-equimolar HEBs possessed excellent oxidation ablation resistance relative to equimolar HEBs.The oxidized surface of(Zr_(1/4)Hf_(1/4)Ta_(1/4)Ti_(1/4))B_(2) formed craters due to excessive liquid products and violent volatilization,while(Hf_(4/5)Zr_(1/15)Ta_(1/15)Ti_(1/15))B_(2) formed a dense oxide layer after oxidation,which had the best antioxidant performance.The content and type of different metal elements significantly affect the oxidative behavior and products,and the ratio of liquid oxidation products plays a critical role in the antioxidant ability.An appropriate amount of liquid that fills the pores of the solid not only better blocks the diffusion channels of oxygen but also promotes the densification of the oxide layer through flow mass transfer.The oxidation of HEBs to generate corresponding high-entropy oxides avoids thermal mismatch between different oxides,reduces cracks and thermal stresses caused by phase transitions or grain growth,and further promotes the formation of a dense scale.This work provides a first look at the oxidation behaviors of non-equimolar HEBs in an ultra-high-temperature environment and proposes guiding rules for the design of HEB components(limiting the ratio of liquid oxidation products to the range of 10–27 mol%).展开更多
It is important to achieve continuous, stable and efficient pumping well operation in actual oilfield operation. Down-hole pumping well working conditions can be monitored in real-time and a reasonable production sche...It is important to achieve continuous, stable and efficient pumping well operation in actual oilfield operation. Down-hole pumping well working conditions can be monitored in real-time and a reasonable production scheme can be designed when computer diagnosis is used. However, it is difficult to make a comprehensive analysis to supply efficient technical guidance for operation of the pumping well with multiple faults of down-hole conditions, which cannot be effectively dealt with by the common methods. To solve this problem, a method based on designated component analysis （DCA） is used in this paper. Freeman chain code is used to represent the down-hole dynamometer card whose important characteristics are extracted to construct a designated mode set. A control chart is used as a basis for fault detection. The upper and lower control lines on the control chart are determined from standard samples in normal working conditions. In an incompletely orthogonal mode, the designated mode set could be divided into some subsets in which the modes are completely orthogonal. The observed data is projected into each designated mode to realize fault detection according to the upper and lower control lines. The examples show that the proposed method can effectively diagnose multiple faults of down-hole conditions.展开更多
One of the biggest global issues at present involves the search for measures to conserve energy and to combat climate change.Because of an increase in natural disasters and energy use,architects and engineers have bee...One of the biggest global issues at present involves the search for measures to conserve energy and to combat climate change.Because of an increase in natural disasters and energy use,architects and engineers have been focusing more on creating green buildings with low-carbon designs.Building information modeling(BIM)is used to record all of the data related to buildings from the early design stage.This information can be used to respond to energy simulation feedback and to accommodate changes that may be necessary during the design developments.To mitigate greenhouse gas emissions and to conserve energy in the buildings,the application of a BIM-based low-carbon design technique is required from the early design stage.However,the existing research is limited to sub-segmented topics;therefore,it is difficult for designers to establish a rank grade for a low-carbon design technique that is required for application in design planning.In this study,we attempt to analyze the rank grade and the correlation among design components that affect a building’s energy performance.We selected tower buildings for the experiment,as they consume a massive amount of energy and have a large impact on the surrounding environment.We analyzed the values that resulted from different shapes,scales,slenderness ratios,window-to-wall ratios,and solar orientations of the tower buildings.Then,we identified a correlation and rank grade among different design components.Architects can maximize energy performance efficiency by considering and applying the rank grade of a low-carbon design technique during design planning.In addition,the development of guidelines for green BIM would reduce confusion in the decision-making process and design modification during the stages of design development,which would then minimize the cost.Furthermore,it is expected that this study can be used to create a database for the realization of green buildings.展开更多
Protonic solid oxide electrolysis cells(P-SOECs)operating at intermediate temperatures,which have low costs,low environmental impact,and high theoretical electrolysis efficiency,are considered promising next-generatio...Protonic solid oxide electrolysis cells(P-SOECs)operating at intermediate temperatures,which have low costs,low environmental impact,and high theoretical electrolysis efficiency,are considered promising next-generation energy conversion devices for green hydrogen production.However,the developments and applications of P-SOECs are restricted by numerous material-and interface-related issues,including carrier mismatch between the anode and electrolyte,current leakage in the electrolyte,poor interfacial contact,and chemical stability.Over the past few decades,considerable attempts have been made to address these issues by improving the properties of P-SOECs.This review comprehensively explores the recent advances in the mechanisms governing steam electrolysis in P-SOECs,optimization strategies,specially designed components,electrochemical performance,and durability.In particular,given that the lack of suitable anode materials has significantly impeded P-SOEC development,the relationships between the transferred carriers and the cell performance,reaction models,and surface decoration approaches are meticulously probed.Finally,the challenges hindering P-SOEC development are discussed and recommendations for future research directions,including theoretical calculations and simulations,structural modification approaches,and large-scale single-cell fabrication,are proposed to stimulate research on P-SOECs and thereby realize efficient electricity-to-hydrogen conversion.展开更多
Supercapacitors(SCs)are one of the most promising electrical energy storage technologies systems due to their fast storage capability,long cycle stability,high power density,and environmental friendliness.Enormous res...Supercapacitors(SCs)are one of the most promising electrical energy storage technologies systems due to their fast storage capability,long cycle stability,high power density,and environmental friendliness.Enormous research has focused on the design of nanomaterials to achieve low cost,highly efficient,and stable electrodes.Ceramic materials provide promising candidates for SCs electrodes.However,the low specific surface area and relatively low surface activity severely hinder the SCs performance of ceramic materials.Therefore,the basic understanding of ceramic materials,the optimization strategy,and the research progress of ceramic electrodes are the key steps to enable good electrical conductivity and excellent electron transport capabilities,and realize economically feasible ceramic electrodes in industry.Herein,we review recent achievements in manufacturing the ceramic electrodes for SCs,including metal oxide ceramics,multi-elemental oxide ceramics,metal hydroxide ceramics,metal sulfide ceramics,carbon-based ceramics,carbide and nitride ceramics,and other special ceramics(MXene).We focus on the unique and key factors in the component and structural design of ceramic electrodes,which correlate them with SCs performance.In addition,the current technical challenges and perspectives of ceramic electrodes for SCs are also discussed.展开更多
基金supported by the National Key R&D Program of China(No.2018YFB0704400)the Shanghai Technical Platform for Testing Inorganic Materials(No.19DZ2290700).
文摘High-entropy borides(HEBs)are unable to serve in environments above 1800℃because of their poor oxidation resistance,which severely limits the application of these materials in ultra-high temperature environments.To solve this problem,a series of HEBs with different ratios of metal elements were designed and prepared in this work,and their oxidation behavior above 1800℃was investigated.The results showed that non-equimolar HEBs possessed excellent oxidation ablation resistance relative to equimolar HEBs.The oxidized surface of(Zr_(1/4)Hf_(1/4)Ta_(1/4)Ti_(1/4))B_(2) formed craters due to excessive liquid products and violent volatilization,while(Hf_(4/5)Zr_(1/15)Ta_(1/15)Ti_(1/15))B_(2) formed a dense oxide layer after oxidation,which had the best antioxidant performance.The content and type of different metal elements significantly affect the oxidative behavior and products,and the ratio of liquid oxidation products plays a critical role in the antioxidant ability.An appropriate amount of liquid that fills the pores of the solid not only better blocks the diffusion channels of oxygen but also promotes the densification of the oxide layer through flow mass transfer.The oxidation of HEBs to generate corresponding high-entropy oxides avoids thermal mismatch between different oxides,reduces cracks and thermal stresses caused by phase transitions or grain growth,and further promotes the formation of a dense scale.This work provides a first look at the oxidation behaviors of non-equimolar HEBs in an ultra-high-temperature environment and proposes guiding rules for the design of HEB components(limiting the ratio of liquid oxidation products to the range of 10–27 mol%).
基金supported by the Key Program of National Natural Science Foundation of China (61034005)Postgraduate Scientific Research and Innovation Projects of Basic Scientific Research Operating Expensesof Ministry of Education (N100604001)Excellent Doctoral Dissertations Cultivation Project of Northeastern University
文摘It is important to achieve continuous, stable and efficient pumping well operation in actual oilfield operation. Down-hole pumping well working conditions can be monitored in real-time and a reasonable production scheme can be designed when computer diagnosis is used. However, it is difficult to make a comprehensive analysis to supply efficient technical guidance for operation of the pumping well with multiple faults of down-hole conditions, which cannot be effectively dealt with by the common methods. To solve this problem, a method based on designated component analysis （DCA） is used in this paper. Freeman chain code is used to represent the down-hole dynamometer card whose important characteristics are extracted to construct a designated mode set. A control chart is used as a basis for fault detection. The upper and lower control lines on the control chart are determined from standard samples in normal working conditions. In an incompletely orthogonal mode, the designated mode set could be divided into some subsets in which the modes are completely orthogonal. The observed data is projected into each designated mode to realize fault detection according to the upper and lower control lines. The examples show that the proposed method can effectively diagnose multiple faults of down-hole conditions.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MEST)(No.2013-065823)。
文摘One of the biggest global issues at present involves the search for measures to conserve energy and to combat climate change.Because of an increase in natural disasters and energy use,architects and engineers have been focusing more on creating green buildings with low-carbon designs.Building information modeling(BIM)is used to record all of the data related to buildings from the early design stage.This information can be used to respond to energy simulation feedback and to accommodate changes that may be necessary during the design developments.To mitigate greenhouse gas emissions and to conserve energy in the buildings,the application of a BIM-based low-carbon design technique is required from the early design stage.However,the existing research is limited to sub-segmented topics;therefore,it is difficult for designers to establish a rank grade for a low-carbon design technique that is required for application in design planning.In this study,we attempt to analyze the rank grade and the correlation among design components that affect a building’s energy performance.We selected tower buildings for the experiment,as they consume a massive amount of energy and have a large impact on the surrounding environment.We analyzed the values that resulted from different shapes,scales,slenderness ratios,window-to-wall ratios,and solar orientations of the tower buildings.Then,we identified a correlation and rank grade among different design components.Architects can maximize energy performance efficiency by considering and applying the rank grade of a low-carbon design technique during design planning.In addition,the development of guidelines for green BIM would reduce confusion in the decision-making process and design modification during the stages of design development,which would then minimize the cost.Furthermore,it is expected that this study can be used to create a database for the realization of green buildings.
基金Huangpu Hydrogen Energy Innovation Center at Guangzhou UniversityLaboratory of Electronic Materials Chemistry at Hokkaido University+1 种基金Basic and Applied Basic Research Foundation of Guangdong Province,Grant/Award Number:2022A1515110470Guangdong Engineering Technology Research Center for Hydrogen Energy and Fuel Cells。
文摘Protonic solid oxide electrolysis cells(P-SOECs)operating at intermediate temperatures,which have low costs,low environmental impact,and high theoretical electrolysis efficiency,are considered promising next-generation energy conversion devices for green hydrogen production.However,the developments and applications of P-SOECs are restricted by numerous material-and interface-related issues,including carrier mismatch between the anode and electrolyte,current leakage in the electrolyte,poor interfacial contact,and chemical stability.Over the past few decades,considerable attempts have been made to address these issues by improving the properties of P-SOECs.This review comprehensively explores the recent advances in the mechanisms governing steam electrolysis in P-SOECs,optimization strategies,specially designed components,electrochemical performance,and durability.In particular,given that the lack of suitable anode materials has significantly impeded P-SOEC development,the relationships between the transferred carriers and the cell performance,reaction models,and surface decoration approaches are meticulously probed.Finally,the challenges hindering P-SOEC development are discussed and recommendations for future research directions,including theoretical calculations and simulations,structural modification approaches,and large-scale single-cell fabrication,are proposed to stimulate research on P-SOECs and thereby realize efficient electricity-to-hydrogen conversion.
基金This work was financially supported by the National Natural Science Foundation of China(51767010).
文摘Supercapacitors(SCs)are one of the most promising electrical energy storage technologies systems due to their fast storage capability,long cycle stability,high power density,and environmental friendliness.Enormous research has focused on the design of nanomaterials to achieve low cost,highly efficient,and stable electrodes.Ceramic materials provide promising candidates for SCs electrodes.However,the low specific surface area and relatively low surface activity severely hinder the SCs performance of ceramic materials.Therefore,the basic understanding of ceramic materials,the optimization strategy,and the research progress of ceramic electrodes are the key steps to enable good electrical conductivity and excellent electron transport capabilities,and realize economically feasible ceramic electrodes in industry.Herein,we review recent achievements in manufacturing the ceramic electrodes for SCs,including metal oxide ceramics,multi-elemental oxide ceramics,metal hydroxide ceramics,metal sulfide ceramics,carbon-based ceramics,carbide and nitride ceramics,and other special ceramics(MXene).We focus on the unique and key factors in the component and structural design of ceramic electrodes,which correlate them with SCs performance.In addition,the current technical challenges and perspectives of ceramic electrodes for SCs are also discussed.
