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
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
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 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 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.
