Objective: This study visualizes and analyzes the current status, hotspots, and frontiers of cardiac rehabilitation for patients with Coronary Heart Disease (CHD) over the past decade (2012.01-2022.12), and explores t...Objective: This study visualizes and analyzes the current status, hotspots, and frontiers of cardiac rehabilitation for patients with Coronary Heart Disease (CHD) over the past decade (2012.01-2022.12), and explores the future development trend and research direction of the CR for CHD patients in China. Methods: Relevant literature was searched, screened and downloaded from the Web of Science (WOS) database, and bibliometric and visualization analyses were performed using CiteSpace VI software. Results: Through the search and screening of related literature, 2443 English articles were finally included. Among them, most of the Chinese publishers were mainly universities and had less connection with each other, while the foreign publishers were mainly universities and medical institutions in the United States and Europe, and had close connection with each other. The research content of Chinese scholars mainly focuses on the assessment of patients’ life and psychological status, as well as the assessment of cardiac function. Foreign research focuses on physical training assessment, disease perception, etc. Conclusion: Through visualizing relevant research with CiteSpace VI software in the form of a knowledge map, the research frontiers and trends in the field of cardiac rehabilitation for coronary heart disease patients in China and abroad can be discovered more intuitively. Compared with foreign research, the development of cardiac rehabilitation for coronary heart disease patients in China is relatively slow and insufficient, and institutions lack cooperation. In the future, China should accelerate the connection between regions in the field of cardiac rehabilitation and develop a cardiac rehabilitation model suitable for coronary heart disease patients in China with its own characteristics.展开更多
Purpose–This study aims to improve the availability of regenerative braking for urban metro vehicles by introducing a sensorless operational temperature estimation method for the braking resistor(BR)onboard the vehic...Purpose–This study aims to improve the availability of regenerative braking for urban metro vehicles by introducing a sensorless operational temperature estimation method for the braking resistor(BR)onboard the vehicle,which overcomes the vulnerability of having conventional temperature sensor.Design/methodology/approach–In this study,the energy model based sensorless estimation method is developed.By analyzing the structure and the convection dissipation process of the BR onboard the vehicle,the energy-based operational temperature model of the BR and its cooling domain is established.By adopting Newton’s law of cooling and the law of conservation of energy,the energy and temperature dynamic of the BR can be stated.To minimize the use of all kinds of sensors(including both thermal and electrical),a novel regenerative braking power calculation method is proposed,which involves only the voltage of DC traction network and the duty cycle of the chopping circuit;both of them are available for the traction control unit(TCU)of the vehicle.By utilizing a real-time iterative calculation and updating the parameter of the energy model,the operational temperature of the BR can be obtained and monitored in a sensorless manner.Findings–In this study,a sensorless estimation/monitoring method of the operational temperature of BR is proposed.The results show that it is possible to utilize the existing electrical sensors that is mandatory for the traction unit’s operation to estimate the operational temperature of BR,instead of adding dedicated thermal sensors.The results also validate the effectiveness of the proposal is acceptable for the engineering practical.Originality/value–The proposal of this study provides novel concepts for the sensorless operational temperature monitoring of BR onboard rolling stocks.The proposed method only involves quasi-global electrical variable and the internal control signal within the TCU.展开更多
SmCo_(5)alloy was prepared via direct calciothermic reduction using anhydrous samarium fluoride(SmF_(3))as raw material and cobalt as inducer.Results of the thermodynamic calculation show that the direct reduction of ...SmCo_(5)alloy was prepared via direct calciothermic reduction using anhydrous samarium fluoride(SmF_(3))as raw material and cobalt as inducer.Results of the thermodynamic calculation show that the direct reduction of cobalt-induced SmF_(3)for preparing SmCo_(5)alloy is feasible.An alloy with 33.89 wt%samarium and a yield of 96.45%were achieved under the optimal conditions of 10%and 20%excess of SmF_(3)and calcium over the stoichiometry,respectively,and 1450℃for 4 min.The X-ray diffraction results show that the reduction products are SmCo_(5)alloy and CaF_(2).The scanning electron microscopy micrograph of the SmCo_(5)alloy ingot exhibits a distinct dendritic morphology composed of samarium and cobalt.The X-ray photoelectron spectroscopy shows that the atomic ratio of samarium to cobalt is approximately 1:5 and both elements demonstrate zero valency(Sm^(0),Co^(0)).The magnetic properties measurement of the SmCo_(5)alloy melt-spun ribbon shows the remanent magnetization B_r=0.59 T,intrinsic coercivity H_(Ci)=345.82 kA/m and maximum magnetic energy density(BH)_(max)=42.20 kJ/m^(3).These results may be helpful for the development of novel valence-variable rare-earth alloys.展开更多
Mixed-matrix membranes(MMMs)have received much attention due to their processable advantages of polymer and high permeability and/or selectivity of porous metal-organic frameworks(MOFs)fillers.However,the interfacial ...Mixed-matrix membranes(MMMs)have received much attention due to their processable advantages of polymer and high permeability and/or selectivity of porous metal-organic frameworks(MOFs)fillers.However,the interfacial defects caused by poor interaction between MOFs with polymers and the agglomeration phenomenon caused by uneven dispersion of MOFs are common problems in mixed-matrix membranes.Currently,the priming protocol is one of solutions to the above problems,but it cannot precisely regulate the dispersion of particles and the interfacial compatibility between two phases.Herein,covalent grafting of polyimide 6FDA-Durene onto the surface of UiO-66-NH2 can mitigate the aggregation of fillers inside the polymeric matrices and improve the interfacial interaction between two phases,thus significantly improving the CO_(2)/CH_(4)separation performance on the as-synthesized MMMs.The explored gas transport mechanism indicated that the improved separation was due to the raise of solubility selectivity.Furthermore,the stronger covalent bond between fillers and polyimide than physical interaction of priming protocol also endows the improved anti-plasticization phenomenon for CO_(2)/CH_(4)separation.展开更多
High-temperature superconducting(HTS) magnets consisting of no-insulation(NI) double-pancake coils(DPCs) with high thermal stability have been proposed for use in the preparation of high-field magnets. However, increa...High-temperature superconducting(HTS) magnets consisting of no-insulation(NI) double-pancake coils(DPCs) with high thermal stability have been proposed for use in the preparation of high-field magnets. However, increased ramp time is a known disadvantage of the NI approach. To solve this problem, a proportional and integral(PI) active feedback control has been proposed in the charging experiments of the NI magnet. In this study, the electromagnetic-thermal-mechanical characteristics of an NI magnet with and without PI are analyzed to ensure the safety and reliability of PI control. Due to the increase in the radial current of the magnet, the turn-to-turn loss energy of the magnet with PI is more than twice that without PI. However, the magnetization loss energy of the magnet has a small difference with and without PI. It can be also found that the NI magnet with PI has a large temperature rise, and thus it has a low thermal stability margin. Moreover, in the high field, the hoop stress and hoop strain peaks of a magnet with PI are larger than those without PI. Thus, PI control can induce a relatively high risk of mechanical damage in the applications of NI magnets.展开更多
The no-insulation(NI)winding approach can remarkably improve the thermal stability of high-temperature superconducting coil.However,mechanical issues have gradually become a key factor to block the development of NI m...The no-insulation(NI)winding approach can remarkably improve the thermal stability of high-temperature superconducting coil.However,mechanical issues have gradually become a key factor to block the development of NI magnets in recent years.This paper mainly analyzes the effect of the overband on the mechanical behaviors of an NI coil during a quench.A numerical model including a quench model combined with a three-dimensional homogeneous mechanical model is employed to study the change of stress in the coil without and with the over band during a local quench.The results show that the overband has an obvious effect on the stress distribution as the heater is located at the outer turn of the coil.Meanwhile,the values of stress in the coil are also affected by the overband.Moreover,the effects of the thickness of the overband and the location of the heater on the mechanical behaviors of the coil are also discussed.It is worth noting that the overband can remarkably reduce the hoop and axial tensile stresses of the coil during a quench。展开更多
文摘Objective: This study visualizes and analyzes the current status, hotspots, and frontiers of cardiac rehabilitation for patients with Coronary Heart Disease (CHD) over the past decade (2012.01-2022.12), and explores the future development trend and research direction of the CR for CHD patients in China. Methods: Relevant literature was searched, screened and downloaded from the Web of Science (WOS) database, and bibliometric and visualization analyses were performed using CiteSpace VI software. Results: Through the search and screening of related literature, 2443 English articles were finally included. Among them, most of the Chinese publishers were mainly universities and had less connection with each other, while the foreign publishers were mainly universities and medical institutions in the United States and Europe, and had close connection with each other. The research content of Chinese scholars mainly focuses on the assessment of patients’ life and psychological status, as well as the assessment of cardiac function. Foreign research focuses on physical training assessment, disease perception, etc. Conclusion: Through visualizing relevant research with CiteSpace VI software in the form of a knowledge map, the research frontiers and trends in the field of cardiac rehabilitation for coronary heart disease patients in China and abroad can be discovered more intuitively. Compared with foreign research, the development of cardiac rehabilitation for coronary heart disease patients in China is relatively slow and insufficient, and institutions lack cooperation. In the future, China should accelerate the connection between regions in the field of cardiac rehabilitation and develop a cardiac rehabilitation model suitable for coronary heart disease patients in China with its own characteristics.
基金supported by the Fund of China Academy of Railway Sciences Corporation Limited(2022YJ230)the Scientific Research Projects of China Association of Metros(CAMET-KY-2022039).
文摘Purpose–This study aims to improve the availability of regenerative braking for urban metro vehicles by introducing a sensorless operational temperature estimation method for the braking resistor(BR)onboard the vehicle,which overcomes the vulnerability of having conventional temperature sensor.Design/methodology/approach–In this study,the energy model based sensorless estimation method is developed.By analyzing the structure and the convection dissipation process of the BR onboard the vehicle,the energy-based operational temperature model of the BR and its cooling domain is established.By adopting Newton’s law of cooling and the law of conservation of energy,the energy and temperature dynamic of the BR can be stated.To minimize the use of all kinds of sensors(including both thermal and electrical),a novel regenerative braking power calculation method is proposed,which involves only the voltage of DC traction network and the duty cycle of the chopping circuit;both of them are available for the traction control unit(TCU)of the vehicle.By utilizing a real-time iterative calculation and updating the parameter of the energy model,the operational temperature of the BR can be obtained and monitored in a sensorless manner.Findings–In this study,a sensorless estimation/monitoring method of the operational temperature of BR is proposed.The results show that it is possible to utilize the existing electrical sensors that is mandatory for the traction unit’s operation to estimate the operational temperature of BR,instead of adding dedicated thermal sensors.The results also validate the effectiveness of the proposal is acceptable for the engineering practical.Originality/value–The proposal of this study provides novel concepts for the sensorless operational temperature monitoring of BR onboard rolling stocks.The proposed method only involves quasi-global electrical variable and the internal control signal within the TCU.
基金Project supported by the National Natural Science Foundation of China(NSFC)(51774155)Jiangxi Provincial Key Research and Development Program(20192BBE50028)the Doctoral Scientific Research Foundation of Jiangxi University of Science and Technology(jxxjbs17077)。
文摘SmCo_(5)alloy was prepared via direct calciothermic reduction using anhydrous samarium fluoride(SmF_(3))as raw material and cobalt as inducer.Results of the thermodynamic calculation show that the direct reduction of cobalt-induced SmF_(3)for preparing SmCo_(5)alloy is feasible.An alloy with 33.89 wt%samarium and a yield of 96.45%were achieved under the optimal conditions of 10%and 20%excess of SmF_(3)and calcium over the stoichiometry,respectively,and 1450℃for 4 min.The X-ray diffraction results show that the reduction products are SmCo_(5)alloy and CaF_(2).The scanning electron microscopy micrograph of the SmCo_(5)alloy ingot exhibits a distinct dendritic morphology composed of samarium and cobalt.The X-ray photoelectron spectroscopy shows that the atomic ratio of samarium to cobalt is approximately 1:5 and both elements demonstrate zero valency(Sm^(0),Co^(0)).The magnetic properties measurement of the SmCo_(5)alloy melt-spun ribbon shows the remanent magnetization B_r=0.59 T,intrinsic coercivity H_(Ci)=345.82 kA/m and maximum magnetic energy density(BH)_(max)=42.20 kJ/m^(3).These results may be helpful for the development of novel valence-variable rare-earth alloys.
基金the National Natural Science Foundation of China(21776124)Jiangsu Provincial NSFC(BK20171459)Foundation of Jiangsu Educational Committee of China(17KJA530004)。
文摘Mixed-matrix membranes(MMMs)have received much attention due to their processable advantages of polymer and high permeability and/or selectivity of porous metal-organic frameworks(MOFs)fillers.However,the interfacial defects caused by poor interaction between MOFs with polymers and the agglomeration phenomenon caused by uneven dispersion of MOFs are common problems in mixed-matrix membranes.Currently,the priming protocol is one of solutions to the above problems,but it cannot precisely regulate the dispersion of particles and the interfacial compatibility between two phases.Herein,covalent grafting of polyimide 6FDA-Durene onto the surface of UiO-66-NH2 can mitigate the aggregation of fillers inside the polymeric matrices and improve the interfacial interaction between two phases,thus significantly improving the CO_(2)/CH_(4)separation performance on the as-synthesized MMMs.The explored gas transport mechanism indicated that the improved separation was due to the raise of solubility selectivity.Furthermore,the stronger covalent bond between fillers and polyimide than physical interaction of priming protocol also endows the improved anti-plasticization phenomenon for CO_(2)/CH_(4)separation.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11872195, and 11932008)Fundamental Research Funds for the Central Universities (Grant No. lzujbky-2020-1)。
文摘High-temperature superconducting(HTS) magnets consisting of no-insulation(NI) double-pancake coils(DPCs) with high thermal stability have been proposed for use in the preparation of high-field magnets. However, increased ramp time is a known disadvantage of the NI approach. To solve this problem, a proportional and integral(PI) active feedback control has been proposed in the charging experiments of the NI magnet. In this study, the electromagnetic-thermal-mechanical characteristics of an NI magnet with and without PI are analyzed to ensure the safety and reliability of PI control. Due to the increase in the radial current of the magnet, the turn-to-turn loss energy of the magnet with PI is more than twice that without PI. However, the magnetization loss energy of the magnet has a small difference with and without PI. It can be also found that the NI magnet with PI has a large temperature rise, and thus it has a low thermal stability margin. Moreover, in the high field, the hoop stress and hoop strain peaks of a magnet with PI are larger than those without PI. Thus, PI control can induce a relatively high risk of mechanical damage in the applications of NI magnets.
基金The authors acknowledge the supports from the National Natural Science Foundation of China(No.11872195)the Fundamental Research Funds for the Central Universities(lzujbky-2020-1)Science and Technology on Ship Integrated Power System Technology Laboratory(No.6142217190).
文摘The no-insulation(NI)winding approach can remarkably improve the thermal stability of high-temperature superconducting coil.However,mechanical issues have gradually become a key factor to block the development of NI magnets in recent years.This paper mainly analyzes the effect of the overband on the mechanical behaviors of an NI coil during a quench.A numerical model including a quench model combined with a three-dimensional homogeneous mechanical model is employed to study the change of stress in the coil without and with the over band during a local quench.The results show that the overband has an obvious effect on the stress distribution as the heater is located at the outer turn of the coil.Meanwhile,the values of stress in the coil are also affected by the overband.Moreover,the effects of the thickness of the overband and the location of the heater on the mechanical behaviors of the coil are also discussed.It is worth noting that the overband can remarkably reduce the hoop and axial tensile stresses of the coil during a quench。