Developing advanced stealth devices to cope with radar-infrared(IR)fusion detection and diverse application scenarios is increasingly demanded,which faces significant challenges due to conflicting microwave and IR clo...Developing advanced stealth devices to cope with radar-infrared(IR)fusion detection and diverse application scenarios is increasingly demanded,which faces significant challenges due to conflicting microwave and IR cloaking mechanisms and functional integration limitations.Here,we propose a multiscale hierarchical structure design,integrating wrinkled MXene IR shielding layer and flexible Fe_(3)O_(4)@C/PDMS microwave absorption layer.The top wrinkled MXene layer induces the intensive diffuse reflection effect,shielding IR radiation signals while allowing microwave to pass through.Meanwhile,the permeable microwaves are assimilated into the bottom Fe_(3)O_(4)@C/PDMS layer via strong magneto-electric synergy.Through theoretical and experimental optimization,the assembled stealth devices realize a near-perfect stealth capability in both X-band(8–12 GHz)and long-wave infrared(8–14μm)wavelength ranges.Specifically,it delivers a radar cross-section reduction of−20 dB m^(2),a large apparent temperature modulation range(ΔT=70℃),and a low average IR emissivity of 0.35.Additionally,the optimal device demonstrates exceptional curved surface conformability,self-cleaning capability(contact angle≈129°),and abrasion resistance(recovery time≈5 s).This design strategy promotes the development of multispectral stealth technology and reinforces its applicability and durability in complex and hostile environments.展开更多
Zinc(Zn)is considered a promising biodegradable metal for implant applications due to its appropriate degradability and favorable osteogenesis properties.In this work,laser powder bed fusion(LPBF)additive manufacturin...Zinc(Zn)is considered a promising biodegradable metal for implant applications due to its appropriate degradability and favorable osteogenesis properties.In this work,laser powder bed fusion(LPBF)additive manufacturing was employed to fabricate pure Zn with a heterogeneous microstructure and exceptional strength-ductility synergy.An optimized processing window of LPBF was established for printing Zn samples with relative densities greater than 99%using a laser power range of 80∼90 W and a scanning speed of 900 mm s−1.The Zn sample printed with a power of 80 W at a speed of 900 mm s−1 exhibited a hierarchical heterogeneous microstructure consisting of millimeter-scale molten pool boundaries,micrometer-scale bimodal grains,and nanometer-scale pre-existing dislocations,due to rapid cooling rates and significant thermal gradients formed in the molten pools.The printed sample exhibited the highest ductility of∼12.1%among all reported LPBF-printed pure Zn to date with appreciable ultimate tensile strength(∼128.7 MPa).Such superior strength-ductility synergy can be attributed to the presence of multiple deformation mechanisms that are primarily governed by heterogeneous deformation-induced hardening resulting from the alternative arrangement of bimodal Zn grains with pre-existing dislocations.Additionally,continuous strain hardening was facilitated through the interactions between deformation twins,grains and dislocations as strain accumulated,further contributing to the superior strength-ductility synergy.These findings provide valuable insights into the deformation behavior and mechanisms underlying exceptional mechanical properties of LPBF-printed Zn and its alloys for implant applications.展开更多
Bimetallic nanocrystals have attracted considerable attention because of their complicated systems,which are far superior to those of their individual constituents.A TiO_(2)-confined PtMnP bimetallic catalyst(PtMnP@Ti...Bimetallic nanocrystals have attracted considerable attention because of their complicated systems,which are far superior to those of their individual constituents.A TiO_(2)-confined PtMnP bimetallic catalyst(PtMnP@TiO_(2)) was prepared using an ultrasonic-assisted coincident strategy,which demonstrated exceptional catalytic activity in the universal hydrogen evolution reaction (HER).Owing to the bimetallic synergistic effect and TiO_(2) confinement,PtMnP@TiO_(x)showed ultrasmall metal nanoparticles (NPs),a higher active Pt^(0) content,adequate activation at the porous surface,and abundant acid sites.Simulations were performed to visualize the strain properties of Mn and Pt during the bending process and demonstrate the high activity of Pt.The Pt-Mn bimetallic catalysts were enriched with Pt NPs,convoyed by electron transfer from Mn to Pt.Briefly,PtMnP@TiO_(2) showed robust evolution reaction activities (an overpotential of 220 mV at a current density of 10 mA cm^(-2) and a Tafel slope of 186 mV dec^(-1))and the ability to contrast stated catalysts without ultrasonication-plasma.This protocol revealed that the geometrical and electronic effects of Pt and P surrounding the Mn species in PtMnP@TiO_(2) were crucial for increasing the catalytic activity (99%) and durability (over 20 cycles),which were far superior to those of other reported catalysts.展开更多
Ni-Fe-based oxides are among the most promising catalysts developed to date for the bottleneck oxygen evolution reaction(OER)in water electrolysis.However,understanding and mastering the synergy of Ni and Fe remain ch...Ni-Fe-based oxides are among the most promising catalysts developed to date for the bottleneck oxygen evolution reaction(OER)in water electrolysis.However,understanding and mastering the synergy of Ni and Fe remain challenging.Herein,we report that the synergy between Ni and Fe can be tailored by crystal dimensionality of Ni,Fe-contained Ruddlesden-Popper(RP)-type perovskites(La_(0.125)Sr_(0.875))n+1(Ni_(0.25)Fe_(0.75))nO3n+1(n=1,2,3),where the material with n=3 shows the best OER performance in alkaline media.Soft X-ray absorption spectroscopy spectra before and after OER reveal that the material with n=3 shows enhanced Ni/Fe-O covalency to boost the electron transfer as compared to those with n=1 and n=2.Further experimental investigations demonstrate that the Fe ion is the active site and the Ni ion is the stable site in this system,where such unique synergy reaches the optimum at n=3.Besides,as n increases,the proportion of unstable rock-salt layers accordingly decreases and the leaching of ions(especially Sr^(2+))into the electrolyte is suppressed,which induces a decrease in the leaching of active Fe ions,ultimately leading to enhanced stability.This work provides a new avenue for rational catalyst design through the dimensional strategy.展开更多
Grain growth of magnesium(Mg)and its hydride is one of the main reasons for kinetic and capacity degradation during the hydrogen absorption and desorption cycles.To solve this problem,herein we propose a novel method ...Grain growth of magnesium(Mg)and its hydride is one of the main reasons for kinetic and capacity degradation during the hydrogen absorption and desorption cycles.To solve this problem,herein we propose a novel method involving synergistic effect of inside embedded metals and outside coated graphene to limit the growth of Mg and its hydride grains.The graphene coated Mg-Y-Al alloys were selected as a model system for demonstrating this positive effect where the Mg_(91)Y_(3)Al_(6)alloy was first prepared by rapidly solidified method and then high-pressure milled with 5 wt%graphene upon 5 MPa hydrogen gas for obtaining in-situ formed YAl_(2)and YH_(3)embedded in the MgH_(2)matrix with graphene shell(denoted as MgH_(2)-Y-Al@GR).In comparison to pure MgH_(2),the obtained MgH_(2)-Y-Al@GR composites deliver much better kinetics and more stable cyclic performance.For instance,the MgH_(2)-Y-Al@GR can release about 6.1 wt%H_(2)within 30 min at 300℃ but pure MgH_(2)only desorbs∼1.5 wt%H_(2).The activation energy for desorption of MgH_(2)-Y-Al@GR samples is calculated to be 75.3±9.1 kJ/mol that is much lower than approximately 160 kJ/mol for pure MgH_(2).Moreover,its capacity retention is promoted from∼57%of pure MgH_(2)to∼84%after 50th cycles without obvious particle agglomeration and grain growth.The synergistic effect of outside graphene coating with inside embedded metals which could provide a huge number of active sites for catalysis as well as inhibit the grain growth of Mg and its hydride is believed to be responsible for these.展开更多
At the intersection of the“dual carbon”goal and the era of digital intelligence(DI),exploring the synergy between pollution and carbon reduction(SPCR)within the context of DI is important for promoting a comprehensi...At the intersection of the“dual carbon”goal and the era of digital intelligence(DI),exploring the synergy between pollution and carbon reduction(SPCR)within the context of DI is important for promoting a comprehensive green transformation of economic and social development.This study,based on urban panel data from 281 prefecture-level cities in China's Mainland from 2010 to 2020,developed a DI indicator system for these cities and employed a double machine learning algorithm for the first time to investigate the intrinsic mechanisms and incentivizing effects of DI on SPCR.The results showed that:①DI significantly promotes SPCR.②Mechanism tests demonstrated that DI can indirectly enhance SPCR by optimizing resource allocation and reinforcing government interventions.③Further analysis showed that the impact of DI on SPCR was more substantial in regions with lower levels of economic and environmental competition.Moreover,the SPCR driven by DI exhibited heterogeneity,characterized by stronger effects in“resource-based cities>non resource-based cities”and“non-capital economic zones>capital economic zones”.The conclusions of this study hold significant implications for fully harnessing the synergy between digitization and intelligence to empower SPCR.In addition,the findings are valuable for the government’s integrated promotion of the“dual carbon”goal and the“digital China”strategy.展开更多
A new synergy decision method for radar and infrared search and track (IRST) data fusion is proposed, to solve such problems as how to decrease opportunities for radar suffering from being locked on by adverse electr...A new synergy decision method for radar and infrared search and track (IRST) data fusion is proposed, to solve such problems as how to decrease opportunities for radar suffering from being locked on by adverse electronic support measures (ESM), how to retrieve range information of the target during radar off, and how to detect the maneuver of the target. Firstly, polynomials used to predict target motion states are constructed. Secondly, a set of discriminants for detecting target maneuver are established by comparing the predicted values with the observations from IRST. Thirdly, a set of decisions are presented. Lastly, simulation is performed on the given scenario to test the validity of the method.展开更多
In order to comprehensively evaluate the flow and heat transfer performance of a large-size annular combustion chamber of a heavy-duty gas turbine,we carried out numerical computation and analyses on the velocity,temp...In order to comprehensively evaluate the flow and heat transfer performance of a large-size annular combustion chamber of a heavy-duty gas turbine,we carried out numerical computation and analyses on the velocity,temperature and pressure fields in the chamber with double swirlers.The mathematical model of the coupling combustion,gas flow,and heat transfer process was established.The influences of the inlet swirling strength,fuel-air ratio and temperature of the premixed gas on the multi-field characteristics and synergy were investigated on the basis of field synergy theory.The results showed that the central recirculation zone induced by the inlet swirling flow grows downstream in the combustion chamber.The velocity and temperature in the outlet section of the chamber tend to be uniform due to the upstream improved synergy.The outer swirl number of the premixed gas flow has a great influence on the comprehensive flow and heat transfer performance of the combustion chamber.The synergy angles change towards benefiting the synergy between velocity and temperature fields with the increasing swirl numbers and inlet gas temperature while the velocity-pressure synergy becomes poor.The increasing fuel-air ratio of premixed gas leads to different trends of the velocity-temperature synergy and velocity-pressure synergy.The comprehensive synergy representing the low-resistance heat transfer performance is evidently dominated mainly by the velocity-temperature synergy.展开更多
We are in the midst of a significant transformation regarding the way we produce products and deliver services thanks to the digitization of manufacturing and new connected supply-chains and co-creation systems.This a...We are in the midst of a significant transformation regarding the way we produce products and deliver services thanks to the digitization of manufacturing and new connected supply-chains and co-creation systems.This article elaborates Digital Twins Approach to the current challenges of knowledge management when Industry 4.0 is emerging in industries and manufacturing.Industry 4.0 approach underlines the importance of Internet of Things and interactions between social and physical systems.Internet of Things(and also Internet of Services and Internet of Data)are new Internet infrastructure that marries advanced manufacturing techniques and service architectures with the I-o-T,I-o-S,and I-o-D to create manufacturing systems that are not only interconnected,but communicate,analyze,and use information to drive further intelligent action back in the physical world.This paper identifies four critical domains of synergy challenge:(1)man-to-man interaction;(2)man-to-machine interaction;(3)machine-to-man interaction;and finally(4)machine-to-machine interaction.Key conclusion is that new knowledge management challenges are closely linked to the challenges of synergic interactions between these four key interactions and accurate measurements of synergic interaction.展开更多
Conical spiral tube bundle are universally used in heat transfer enhancement in heat exchangers.The heat transfer and resistance of the tube bundle are affected greatly by the conical structure,so the analysis of it i...Conical spiral tube bundle are universally used in heat transfer enhancement in heat exchangers.The heat transfer and resistance of the tube bundle are affected greatly by the conical structure,so the analysis of it is necessary.In order to a further evaluation,the heat transfer and resistance characteristics of conical spiral tube bundle are investigated with regression analysis based on numerical simulation data.The correlations of heat transfer and pressure drop of conical spiral tube bundle are proposed both in laminar and turbulent fluid flow.On the based of the field synergy principle,the synergy of four vectors,the velocity,the velocity gradient,the temperature gradient and the pressure gradient,are calculated and discussed via the user defined function(UDF) program.The synergy angles β and θ,which respectively denote the performance of heat transfer enhancement and pressure drop of the conical spiral tube bundle,are analyzed.Finally,the comprehensive performance of the conical spiral tube is evaluated by the synergy angle γ and all of the three synergy angles of conical spiral tube bundle are compared to both bare tube and thin cylinder-interpolated tube.The analysis of the synergy angles shows that the heat transfer enhancement and pressure drop of conical spiral tube bundle are smaller than that of the thin cylinder-interpolated tube,while the comprehensive performance of conical spiral tube bundle is greater.The analysis of the heat transfer and pressure drop of conical spiral tube is valuable and instructional on the design and optimum of conical spiral tube bundle heat exchangers.展开更多
基金financial support from the National Nature Science Foundation of China(No.52273247)the National Science and Technology Major Project of China(J2019-VI-0017-0132).
文摘Developing advanced stealth devices to cope with radar-infrared(IR)fusion detection and diverse application scenarios is increasingly demanded,which faces significant challenges due to conflicting microwave and IR cloaking mechanisms and functional integration limitations.Here,we propose a multiscale hierarchical structure design,integrating wrinkled MXene IR shielding layer and flexible Fe_(3)O_(4)@C/PDMS microwave absorption layer.The top wrinkled MXene layer induces the intensive diffuse reflection effect,shielding IR radiation signals while allowing microwave to pass through.Meanwhile,the permeable microwaves are assimilated into the bottom Fe_(3)O_(4)@C/PDMS layer via strong magneto-electric synergy.Through theoretical and experimental optimization,the assembled stealth devices realize a near-perfect stealth capability in both X-band(8–12 GHz)and long-wave infrared(8–14μm)wavelength ranges.Specifically,it delivers a radar cross-section reduction of−20 dB m^(2),a large apparent temperature modulation range(ΔT=70℃),and a low average IR emissivity of 0.35.Additionally,the optimal device demonstrates exceptional curved surface conformability,self-cleaning capability(contact angle≈129°),and abrasion resistance(recovery time≈5 s).This design strategy promotes the development of multispectral stealth technology and reinforces its applicability and durability in complex and hostile environments.
基金National Natural Science Foundation of China (52305358)the Fundamental Research Funds for the Central Universities (2023ZYGXZR061)+3 种基金Guangdong Basic and Applied Basic Research Foundation (2022A1515010304)Science and Technology Program of Guangzhou (202201010362)Young Elite Scientists Sponsorship Program by CAST . (2023QNRC001)Young Talent Support Project of Guangzhou (QT-2023-001)
文摘Zinc(Zn)is considered a promising biodegradable metal for implant applications due to its appropriate degradability and favorable osteogenesis properties.In this work,laser powder bed fusion(LPBF)additive manufacturing was employed to fabricate pure Zn with a heterogeneous microstructure and exceptional strength-ductility synergy.An optimized processing window of LPBF was established for printing Zn samples with relative densities greater than 99%using a laser power range of 80∼90 W and a scanning speed of 900 mm s−1.The Zn sample printed with a power of 80 W at a speed of 900 mm s−1 exhibited a hierarchical heterogeneous microstructure consisting of millimeter-scale molten pool boundaries,micrometer-scale bimodal grains,and nanometer-scale pre-existing dislocations,due to rapid cooling rates and significant thermal gradients formed in the molten pools.The printed sample exhibited the highest ductility of∼12.1%among all reported LPBF-printed pure Zn to date with appreciable ultimate tensile strength(∼128.7 MPa).Such superior strength-ductility synergy can be attributed to the presence of multiple deformation mechanisms that are primarily governed by heterogeneous deformation-induced hardening resulting from the alternative arrangement of bimodal Zn grains with pre-existing dislocations.Additionally,continuous strain hardening was facilitated through the interactions between deformation twins,grains and dislocations as strain accumulated,further contributing to the superior strength-ductility synergy.These findings provide valuable insights into the deformation behavior and mechanisms underlying exceptional mechanical properties of LPBF-printed Zn and its alloys for implant applications.
基金supported by the National Research Foundation of Republic Korea (NRF-2022R1A2C1004392)。
文摘Bimetallic nanocrystals have attracted considerable attention because of their complicated systems,which are far superior to those of their individual constituents.A TiO_(2)-confined PtMnP bimetallic catalyst(PtMnP@TiO_(2)) was prepared using an ultrasonic-assisted coincident strategy,which demonstrated exceptional catalytic activity in the universal hydrogen evolution reaction (HER).Owing to the bimetallic synergistic effect and TiO_(2) confinement,PtMnP@TiO_(x)showed ultrasmall metal nanoparticles (NPs),a higher active Pt^(0) content,adequate activation at the porous surface,and abundant acid sites.Simulations were performed to visualize the strain properties of Mn and Pt during the bending process and demonstrate the high activity of Pt.The Pt-Mn bimetallic catalysts were enriched with Pt NPs,convoyed by electron transfer from Mn to Pt.Briefly,PtMnP@TiO_(2) showed robust evolution reaction activities (an overpotential of 220 mV at a current density of 10 mA cm^(-2) and a Tafel slope of 186 mV dec^(-1))and the ability to contrast stated catalysts without ultrasonication-plasma.This protocol revealed that the geometrical and electronic effects of Pt and P surrounding the Mn species in PtMnP@TiO_(2) were crucial for increasing the catalytic activity (99%) and durability (over 20 cycles),which were far superior to those of other reported catalysts.
基金Guangdong Basic and Applied Basic Research Foundation,Grant/Award Number:2023A1515012878Natural Science Foundation of Anhui Province,Grant/Award Number:2008085ME134+2 种基金Australian Research Council Discovery Projects,Grant/Award Numbers:ARC DP200103315,ARC DP200103332Major Special Science and Technology Project of Anhui Province,Grant/Award Number:202103a07020007Key Research and Development Program of Anhui Province,Grant/Award Number:202104a05020057。
文摘Ni-Fe-based oxides are among the most promising catalysts developed to date for the bottleneck oxygen evolution reaction(OER)in water electrolysis.However,understanding and mastering the synergy of Ni and Fe remain challenging.Herein,we report that the synergy between Ni and Fe can be tailored by crystal dimensionality of Ni,Fe-contained Ruddlesden-Popper(RP)-type perovskites(La_(0.125)Sr_(0.875))n+1(Ni_(0.25)Fe_(0.75))nO3n+1(n=1,2,3),where the material with n=3 shows the best OER performance in alkaline media.Soft X-ray absorption spectroscopy spectra before and after OER reveal that the material with n=3 shows enhanced Ni/Fe-O covalency to boost the electron transfer as compared to those with n=1 and n=2.Further experimental investigations demonstrate that the Fe ion is the active site and the Ni ion is the stable site in this system,where such unique synergy reaches the optimum at n=3.Besides,as n increases,the proportion of unstable rock-salt layers accordingly decreases and the leaching of ions(especially Sr^(2+))into the electrolyte is suppressed,which induces a decrease in the leaching of active Fe ions,ultimately leading to enhanced stability.This work provides a new avenue for rational catalyst design through the dimensional strategy.
基金financially supported by the Key Program for International S&T Cooperation Projects of China(No.2017YFE0124300)National Natural Science Foundation of China(No.52171205,51971002 and 52171197)+1 种基金Scientific Research Foundation of Anhui Provincial Education Department(Nos.KJ2020ZD26,KJ2021A0360)Anhui Provincial Natural Science Foundation for Excellent Youth Scholars(No.2108085Y16).
文摘Grain growth of magnesium(Mg)and its hydride is one of the main reasons for kinetic and capacity degradation during the hydrogen absorption and desorption cycles.To solve this problem,herein we propose a novel method involving synergistic effect of inside embedded metals and outside coated graphene to limit the growth of Mg and its hydride grains.The graphene coated Mg-Y-Al alloys were selected as a model system for demonstrating this positive effect where the Mg_(91)Y_(3)Al_(6)alloy was first prepared by rapidly solidified method and then high-pressure milled with 5 wt%graphene upon 5 MPa hydrogen gas for obtaining in-situ formed YAl_(2)and YH_(3)embedded in the MgH_(2)matrix with graphene shell(denoted as MgH_(2)-Y-Al@GR).In comparison to pure MgH_(2),the obtained MgH_(2)-Y-Al@GR composites deliver much better kinetics and more stable cyclic performance.For instance,the MgH_(2)-Y-Al@GR can release about 6.1 wt%H_(2)within 30 min at 300℃ but pure MgH_(2)only desorbs∼1.5 wt%H_(2).The activation energy for desorption of MgH_(2)-Y-Al@GR samples is calculated to be 75.3±9.1 kJ/mol that is much lower than approximately 160 kJ/mol for pure MgH_(2).Moreover,its capacity retention is promoted from∼57%of pure MgH_(2)to∼84%after 50th cycles without obvious particle agglomeration and grain growth.The synergistic effect of outside graphene coating with inside embedded metals which could provide a huge number of active sites for catalysis as well as inhibit the grain growth of Mg and its hydride is believed to be responsible for these.
基金funded by the General Program of the National Natural Science Foundation of China [Grant No.72473059]the Ministry of Education Humanities and Social Science Planning Fund Project [Grant No.23YJA790026]+1 种基金the Yunnan Province Basic Research Program General Project [Grant No.202401AT070393]the Innovation and Development Research Think Tank for Resource based Industries at Kunming University of Technology [Grant No.XXZK20-23006].
文摘At the intersection of the“dual carbon”goal and the era of digital intelligence(DI),exploring the synergy between pollution and carbon reduction(SPCR)within the context of DI is important for promoting a comprehensive green transformation of economic and social development.This study,based on urban panel data from 281 prefecture-level cities in China's Mainland from 2010 to 2020,developed a DI indicator system for these cities and employed a double machine learning algorithm for the first time to investigate the intrinsic mechanisms and incentivizing effects of DI on SPCR.The results showed that:①DI significantly promotes SPCR.②Mechanism tests demonstrated that DI can indirectly enhance SPCR by optimizing resource allocation and reinforcing government interventions.③Further analysis showed that the impact of DI on SPCR was more substantial in regions with lower levels of economic and environmental competition.Moreover,the SPCR driven by DI exhibited heterogeneity,characterized by stronger effects in“resource-based cities>non resource-based cities”and“non-capital economic zones>capital economic zones”.The conclusions of this study hold significant implications for fully harnessing the synergy between digitization and intelligence to empower SPCR.In addition,the findings are valuable for the government’s integrated promotion of the“dual carbon”goal and the“digital China”strategy.
文摘A new synergy decision method for radar and infrared search and track (IRST) data fusion is proposed, to solve such problems as how to decrease opportunities for radar suffering from being locked on by adverse electronic support measures (ESM), how to retrieve range information of the target during radar off, and how to detect the maneuver of the target. Firstly, polynomials used to predict target motion states are constructed. Secondly, a set of discriminants for detecting target maneuver are established by comparing the predicted values with the observations from IRST. Thirdly, a set of decisions are presented. Lastly, simulation is performed on the given scenario to test the validity of the method.
基金the National Natural Science Foundation of China(No.51606114)Science and Technology Commission of Shanghai Municipality(Nos.19020500900,16020500700)to this study are acknowledged and highly appreciated.
文摘In order to comprehensively evaluate the flow and heat transfer performance of a large-size annular combustion chamber of a heavy-duty gas turbine,we carried out numerical computation and analyses on the velocity,temperature and pressure fields in the chamber with double swirlers.The mathematical model of the coupling combustion,gas flow,and heat transfer process was established.The influences of the inlet swirling strength,fuel-air ratio and temperature of the premixed gas on the multi-field characteristics and synergy were investigated on the basis of field synergy theory.The results showed that the central recirculation zone induced by the inlet swirling flow grows downstream in the combustion chamber.The velocity and temperature in the outlet section of the chamber tend to be uniform due to the upstream improved synergy.The outer swirl number of the premixed gas flow has a great influence on the comprehensive flow and heat transfer performance of the combustion chamber.The synergy angles change towards benefiting the synergy between velocity and temperature fields with the increasing swirl numbers and inlet gas temperature while the velocity-pressure synergy becomes poor.The increasing fuel-air ratio of premixed gas leads to different trends of the velocity-temperature synergy and velocity-pressure synergy.The comprehensive synergy representing the low-resistance heat transfer performance is evidently dominated mainly by the velocity-temperature synergy.
文摘We are in the midst of a significant transformation regarding the way we produce products and deliver services thanks to the digitization of manufacturing and new connected supply-chains and co-creation systems.This article elaborates Digital Twins Approach to the current challenges of knowledge management when Industry 4.0 is emerging in industries and manufacturing.Industry 4.0 approach underlines the importance of Internet of Things and interactions between social and physical systems.Internet of Things(and also Internet of Services and Internet of Data)are new Internet infrastructure that marries advanced manufacturing techniques and service architectures with the I-o-T,I-o-S,and I-o-D to create manufacturing systems that are not only interconnected,but communicate,analyze,and use information to drive further intelligent action back in the physical world.This paper identifies four critical domains of synergy challenge:(1)man-to-man interaction;(2)man-to-machine interaction;(3)machine-to-man interaction;and finally(4)machine-to-machine interaction.Key conclusion is that new knowledge management challenges are closely linked to the challenges of synergic interactions between these four key interactions and accurate measurements of synergic interaction.
基金supported by National Basic Research Program of China(973 Program,Grant No. 2007CB206900)Scholarship Award for Doctoral by Ministry of Education of China(Grant No. 10000071183646)
文摘Conical spiral tube bundle are universally used in heat transfer enhancement in heat exchangers.The heat transfer and resistance of the tube bundle are affected greatly by the conical structure,so the analysis of it is necessary.In order to a further evaluation,the heat transfer and resistance characteristics of conical spiral tube bundle are investigated with regression analysis based on numerical simulation data.The correlations of heat transfer and pressure drop of conical spiral tube bundle are proposed both in laminar and turbulent fluid flow.On the based of the field synergy principle,the synergy of four vectors,the velocity,the velocity gradient,the temperature gradient and the pressure gradient,are calculated and discussed via the user defined function(UDF) program.The synergy angles β and θ,which respectively denote the performance of heat transfer enhancement and pressure drop of the conical spiral tube bundle,are analyzed.Finally,the comprehensive performance of the conical spiral tube is evaluated by the synergy angle γ and all of the three synergy angles of conical spiral tube bundle are compared to both bare tube and thin cylinder-interpolated tube.The analysis of the synergy angles shows that the heat transfer enhancement and pressure drop of conical spiral tube bundle are smaller than that of the thin cylinder-interpolated tube,while the comprehensive performance of conical spiral tube bundle is greater.The analysis of the heat transfer and pressure drop of conical spiral tube is valuable and instructional on the design and optimum of conical spiral tube bundle heat exchangers.