Metal composites produced through the liquid metal dealloying(LMD)process feature an advanced matrix-matrix composite structure,where two metallic materials form a continuous,three-dimensional interconnected network.T...Metal composites produced through the liquid metal dealloying(LMD)process feature an advanced matrix-matrix composite structure,where two metallic materials form a continuous,three-dimensional interconnected network.This study investigates the effects of Ti Cu precursor compositions on dealloying behavior and microstructural evolution in liquid Mg,using Ti_(50)Cu_(50)and Ti_(30)Cu_(70)precursors.The initial microstructure of the precursor significantly influences dealloying kinetics and phase transitions.The single-phase Ti_(50)Cu_(50)precursor exhibits a faster initial dealloying rate due to its homogeneous structure,yet complete dealloying requires 90 min.In contrast,the dualphase Ti_(30)Cu_(70)precursor achieves complete dealloying in 30 min,demonstrating the impact of a higher Cu concentration on accelerating the process kinetics.Additionally,the study explores the coarsening behavior and hardness variations during the LMD process,along with the microstructural characteristics of Mg-Ti composites fabricated from these two precursors.The findings highlight the critical role of precursor composition in tailoring the microstructure and properties of Mg-Ti composites produced through the LMD process,demonstrating its potential for advanced composite material manufacturing.展开更多
The decentralized stabilization of continuous and discrete linear large scale systems with symmetric circulant structure was studied.A few sufficient conditions on decentralized stabilization of such systems were prop...The decentralized stabilization of continuous and discrete linear large scale systems with symmetric circulant structure was studied.A few sufficient conditions on decentralized stabilization of such systems were proposed.For the continuous systems,by introducing a concept called the magnitude of interconnected structure,a very important property that the decentralized stabilization of such systems is fully determined by the structure of each isolated subsystem that is obtained when the magnitude of interconnected structure of the overall system is given.So the decentralized stabilization of such systems can be got by only appropriately designing or modifying the structure of each isolated subsystem,no matter how complicated the interconnected structure of the overall system is.A algorithm for obtaining decentralized state feedback to stabilize the overall system is given.The discrete systems were also discussed.The results show that there is a great dfference on decentralized stabilization between continuous case and discrete case.展开更多
The importance of the zeros of multwariable linear systems is well-knoiun in terms of measure obstructions to the controllability and the. observability. In this paper, a recursive decarnposi Am oj interconnected syst...The importance of the zeros of multwariable linear systems is well-knoiun in terms of measure obstructions to the controllability and the. observability. In this paper, a recursive decarnposi Am oj interconnected systems is outlined by taking into account the sequential structure of the connnections. The paper extends the, coordinate, module-theoretic studies from the elementary algebraic systems theory to include the case oj such linear interconnected systems which need not to be controllable or observable. Also, the properties of controllability and observability, the decoupling zeros and the signal Making issues are characterized.展开更多
Realizing high-rate capability and high-efficiency utilization of polyanionic cathode materials is of great importance for practical sodium-ion batteries(SIBs) since they usually suffer from extremely low electronic c...Realizing high-rate capability and high-efficiency utilization of polyanionic cathode materials is of great importance for practical sodium-ion batteries(SIBs) since they usually suffer from extremely low electronic conductivity and limited ionic diffusion kinetics. Herein, taking Na_(3.5)V_(1.5)Mn_(0.5)(PO_(4))_(3)(NVMP) as an example, a reinforced concrete-like hierarchical and porous hybrid(NVMP@C@3DPG) built from 3D graphene(“rebar”) frameworks and in situ generated carbon coated NVMP(“concrete”) has been developed by a facile polymer assisted self-assembly and subsequent solid-state method. Such hybrids deliver superior rate capability(73.9 m Ah/g up to 20 C) and excellent cycling stability in a wide temperature range with a high specific capacity of 88.4 m Ah/g after 5000 cycles at 15 C at room temperature, and a high capacity retention of 97.1% after 500 cycles at 1 C(-20 ℃), and maintaining a high reversible capacity of 110.3 m Ah/g in full cell. This work offers a facile and efficient strategy to develop advanced polyanionic cathodes with high-efficiency utilization and 3D electron/ion transport systems.展开更多
Tin (Sn) metal foil is a promising anode for next-generation high-energy–density lithium-ion batteries (LIBs) due to its high capacity and easy processibility. However, the pristine Sn foil anode suffers nonuniform a...Tin (Sn) metal foil is a promising anode for next-generation high-energy–density lithium-ion batteries (LIBs) due to its high capacity and easy processibility. However, the pristine Sn foil anode suffers nonuniform alloying/dealloying reaction with lithium (Li) and huge volume variation, leading to electrode pulverization and inferior electrochemical performance. Herein, we proposed that reduced grain size and elaborate porosity design of Sn foil can circumvent the nonuniform alloy reaction and buffer the volume change during the lithiation/delithiation cycling. Experimentally, we designed a three-dimensional interconnected porous Sn (3DIP-Sn) foil by a facile chemical alloying/dealloying approach, which showed improved electrochemical performance. The enhanced structure stability of the as-fabricated 3DIP-Sn foil was verified by chemo-mechanical simulations and experimental investigation. As expected, the 3DIP-Sn foil anode revealed a long cycle lifespan of 4400 h at 0.5 mA cm^(−2) and 1 mAh cm^(−2) in Sn||Li half cells. A 3DIP-Sn||LiFePO_(4) full cell with LiFePO_(4) loading of 7.1 mg cm^(−2) exhibited stable cycling for 500 cycles with 80% capacity retention at 70 mA g^(−1). Pairing with high-loading commercial LiNi0.6Co0.2Mn0.2O_(2) (NCM622, 18.4 mg cm^(−2)) cathode, a 3DIP-Sn||NCM622 full cell delivered a high reversible capacity of 3.2 mAh cm^(−2). These results demonstrated the important role of regulating the uniform alloying/dealloying reaction and circumventing the localized strain/stress in improving the electrochemical performance of Sn foil anodes for advanced LIBs.展开更多
A new theoretical model of gray cast iron taking into account a locally interconnected structure of flake graphite was designed,and the corresponding effective thermal conductivity was calculated using the thermal res...A new theoretical model of gray cast iron taking into account a locally interconnected structure of flake graphite was designed,and the corresponding effective thermal conductivity was calculated using the thermal resistance network method.The calculated results are obviously higher than that of the effective medium approximation assuming that graphite is distributed in isolation.It is suggested that the interconnected structure significantly enhances the overall thermal conductivity.Moreover,it is shown that high anisotropy of graphite thermal conductivity,high volume fraction of graphite,and small aspect ratio of flake graphite will cause the connectivity effects of graphite to more obviously improve the overall thermal conductivity.Higher graphite volume fraction,lower aspect ratio and higher matrix thermal conductivity are beneficial to obtain a high thermal conductivity gray cast iron.This work can provide guidance and reference for the development of high thermal conductivity gray cast iron and the design of high thermal conductivity composites with similar locally interconnected structures.展开更多
The generation of power semiconductor devicesdefinesa generation of power electronicconverters.The efficiency and switching speed of power devices continue to improve,leading to higher converter operating frequenciesa...The generation of power semiconductor devicesdefinesa generation of power electronicconverters.The efficiency and switching speed of power devices continue to improve,leading to higher converter operating frequenciesand a continuous increase in power density.In particular,the emergence and widespread application of wide-bandgap power devices,such as silicon carbide and gallium nitride,have accelerated the process of high-frequencyconverter operations,significantly improving the power density of converters,whichstillhaveconsiderable room forimprovement.One significant change brought about by high-frequency operation of converters is the increased impact of parasiticson circuit operation.With the significant increase in the system switching frequency and the dv/dtanddi/dtof device switching,parasiticshave a greaterinfluenceon circuitoperation.Over the past decade,severalstudieson the analysisand modeling ofparasitics have been published for various devicesin converters,such as transformers,inductors,capacitors,and power devices;however,there is currently a lack of a comprehensive review to summarize the aboveresearch.Adetailed summary of parasiticsin power electronic convertersis included,providinga systematic understanding of past work and future prospects.展开更多
Understanding the microstructure-property relationship from the microscopic and macroscopic perspectives,instead of semi-empirical rules,can facilitate the design of microcosmic morphology to adjust the impedance matc...Understanding the microstructure-property relationship from the microscopic and macroscopic perspectives,instead of semi-empirical rules,can facilitate the design of microcosmic morphology to adjust the impedance matching and dielectric loss of the carbon-based materials,which are still lacking so far.In this study,a clear correlation between microstructure and conduction loss was revealed in agarosederived carbon using a facile salt-etching strategy,in which ferric nitrate acted more as a morphology modifier for bulky carbon rather than a component regulator.Specifically,with the increasing amount of ferric nitrate,the original smooth bulky carbon was etched with caves,which gradually enlarged in size and depth and thus thinned in wall,and eventually transformed into a three-dimensional(3D)interconnected cellular structure,accompanied by a gradual increase in conductivity.Benefiting from the optimal impedance matching and strong conduction loss originating from the unique 3D cellular structure of agarose-derived carbon,AF-3 exhibited super-wide and strong absorption with an effective absorption bandwidth of 7.28 GHz(10.32-17.60 GHz,2.9 mm)and a minimum reflection loss of-46.6 dB(15.6 GHz,2.5 mm).This study establishes the relationship between microstructure,dielectric properties,and loss mechanism in carbon-based materials and also provides a new insight into the fine modulation of EMW-absorbing properties from morphological design.展开更多
The macro-pore sizes of porous scaffold play a key role for regulating ectopic osteogenesis and angiogenesis but many researches ignored the influence of interconnection between macro-pores with different sizes.In ord...The macro-pore sizes of porous scaffold play a key role for regulating ectopic osteogenesis and angiogenesis but many researches ignored the influence of interconnection between macro-pores with different sizes.In order to accurately reveal the relationship between ectopic osteogenesis and macro-pore sizes in dorsal muscle and abdominal cavities of dogs,hydroxyapatite(HA)scaffolds with three different macro-pore sizes of 500–650,750–900 and 1100–1250 mm were prepared via sugar spheres-leaching process,which also had similar interconnecting structure determined by keeping the d/s ratio of interconnecting window diameter to macro-pore size constant.The permeability test showed that the seepage flow of fluid through the porous scaffolds increased with the increase of macro-pore sizes.The cell growth in three scaffolds was not affected by the macro-pore sizes.The in vivo ectopic implantation results indicated that the macro-pore sizes of HA scaffolds with the similar interconnecting structure have impact not only the speed of osteogenesis and angiogenesis but also the space distribution of newly formed bone.The scaffold with macro-pore sizes of 750–900 mm exhibited much faster angiogenesis and osteogenesis,and much more uniformly distribution of new bone than those with othermacro-pore sizes.This work illustrates the importance of a suitable macro-pore sizes in HA scaffolds with the similar interconnecting structure which provides the environment for ectopic osteogenesis and angiogenesis.展开更多
Three-dimensional(3D)-printed scaffolds are widely used in tissue engineering to help regenerate critical-sized bone defects.However,conventional scaffolds possess relatively simple porous structures that limit the de...Three-dimensional(3D)-printed scaffolds are widely used in tissue engineering to help regenerate critical-sized bone defects.However,conventional scaffolds possess relatively simple porous structures that limit the delivery of oxygen and nutrients to cells,leading to insufficient bone regeneration.Accordingly,in the present study,perfusable and permeable polycaprolactone scaffolds with highly interconnected hollow-pipe structures that mimic natural micro-vascular networks are prepared by an indirect onepot 3D-printing method.In vitro experiments demonstrate that hollow-pipe-structured(HPS)scaffolds promote cell attachment,proliferation,osteogenesis and angiogenesis compared to the normal non-hollow-pipe-structured scaffolds.Furthermore,in vivo studies reveal that HPS scaffolds enhance bone regeneration and vascularization in rabbit bone defects,as observed at 8 and 12weeks,respectively.Thus,the fabricated HPS scaffolds are promising candidates for the repair of critical-sized bone defects.展开更多
基金supported by the National Research Foundation of Korea(NRF)grants funded by the Korea government(MSIT)(Nos.RS-2024–00351052 and RS-2024–00450561)。
文摘Metal composites produced through the liquid metal dealloying(LMD)process feature an advanced matrix-matrix composite structure,where two metallic materials form a continuous,three-dimensional interconnected network.This study investigates the effects of Ti Cu precursor compositions on dealloying behavior and microstructural evolution in liquid Mg,using Ti_(50)Cu_(50)and Ti_(30)Cu_(70)precursors.The initial microstructure of the precursor significantly influences dealloying kinetics and phase transitions.The single-phase Ti_(50)Cu_(50)precursor exhibits a faster initial dealloying rate due to its homogeneous structure,yet complete dealloying requires 90 min.In contrast,the dualphase Ti_(30)Cu_(70)precursor achieves complete dealloying in 30 min,demonstrating the impact of a higher Cu concentration on accelerating the process kinetics.Additionally,the study explores the coarsening behavior and hardness variations during the LMD process,along with the microstructural characteristics of Mg-Ti composites fabricated from these two precursors.The findings highlight the critical role of precursor composition in tailoring the microstructure and properties of Mg-Ti composites produced through the LMD process,demonstrating its potential for advanced composite material manufacturing.
文摘The decentralized stabilization of continuous and discrete linear large scale systems with symmetric circulant structure was studied.A few sufficient conditions on decentralized stabilization of such systems were proposed.For the continuous systems,by introducing a concept called the magnitude of interconnected structure,a very important property that the decentralized stabilization of such systems is fully determined by the structure of each isolated subsystem that is obtained when the magnitude of interconnected structure of the overall system is given.So the decentralized stabilization of such systems can be got by only appropriately designing or modifying the structure of each isolated subsystem,no matter how complicated the interconnected structure of the overall system is.A algorithm for obtaining decentralized state feedback to stabilize the overall system is given.The discrete systems were also discussed.The results show that there is a great dfference on decentralized stabilization between continuous case and discrete case.
文摘The importance of the zeros of multwariable linear systems is well-knoiun in terms of measure obstructions to the controllability and the. observability. In this paper, a recursive decarnposi Am oj interconnected systems is outlined by taking into account the sequential structure of the connnections. The paper extends the, coordinate, module-theoretic studies from the elementary algebraic systems theory to include the case oj such linear interconnected systems which need not to be controllable or observable. Also, the properties of controllability and observability, the decoupling zeros and the signal Making issues are characterized.
基金financially supported by the National Natural Science Foundation of China (No.52072119)Natural Science Foundation of Hunan Province (No.2023JJ50015)+2 种基金the 111 Project (No.D20015)the Australian Research Council (No.DP230100198)the Echidna at the Australian centre for Neutron Scattering under Merit Programs (beamtime: M13623)。
文摘Realizing high-rate capability and high-efficiency utilization of polyanionic cathode materials is of great importance for practical sodium-ion batteries(SIBs) since they usually suffer from extremely low electronic conductivity and limited ionic diffusion kinetics. Herein, taking Na_(3.5)V_(1.5)Mn_(0.5)(PO_(4))_(3)(NVMP) as an example, a reinforced concrete-like hierarchical and porous hybrid(NVMP@C@3DPG) built from 3D graphene(“rebar”) frameworks and in situ generated carbon coated NVMP(“concrete”) has been developed by a facile polymer assisted self-assembly and subsequent solid-state method. Such hybrids deliver superior rate capability(73.9 m Ah/g up to 20 C) and excellent cycling stability in a wide temperature range with a high specific capacity of 88.4 m Ah/g after 5000 cycles at 15 C at room temperature, and a high capacity retention of 97.1% after 500 cycles at 1 C(-20 ℃), and maintaining a high reversible capacity of 110.3 m Ah/g in full cell. This work offers a facile and efficient strategy to develop advanced polyanionic cathodes with high-efficiency utilization and 3D electron/ion transport systems.
基金This work is financially supported by the National Natural Science Foundation of China(Grant Nos.52072137,51802105).
文摘Tin (Sn) metal foil is a promising anode for next-generation high-energy–density lithium-ion batteries (LIBs) due to its high capacity and easy processibility. However, the pristine Sn foil anode suffers nonuniform alloying/dealloying reaction with lithium (Li) and huge volume variation, leading to electrode pulverization and inferior electrochemical performance. Herein, we proposed that reduced grain size and elaborate porosity design of Sn foil can circumvent the nonuniform alloy reaction and buffer the volume change during the lithiation/delithiation cycling. Experimentally, we designed a three-dimensional interconnected porous Sn (3DIP-Sn) foil by a facile chemical alloying/dealloying approach, which showed improved electrochemical performance. The enhanced structure stability of the as-fabricated 3DIP-Sn foil was verified by chemo-mechanical simulations and experimental investigation. As expected, the 3DIP-Sn foil anode revealed a long cycle lifespan of 4400 h at 0.5 mA cm^(−2) and 1 mAh cm^(−2) in Sn||Li half cells. A 3DIP-Sn||LiFePO_(4) full cell with LiFePO_(4) loading of 7.1 mg cm^(−2) exhibited stable cycling for 500 cycles with 80% capacity retention at 70 mA g^(−1). Pairing with high-loading commercial LiNi0.6Co0.2Mn0.2O_(2) (NCM622, 18.4 mg cm^(−2)) cathode, a 3DIP-Sn||NCM622 full cell delivered a high reversible capacity of 3.2 mAh cm^(−2). These results demonstrated the important role of regulating the uniform alloying/dealloying reaction and circumventing the localized strain/stress in improving the electrochemical performance of Sn foil anodes for advanced LIBs.
基金the National Natural Science Foundation of China(Grant No.51371104)。
文摘A new theoretical model of gray cast iron taking into account a locally interconnected structure of flake graphite was designed,and the corresponding effective thermal conductivity was calculated using the thermal resistance network method.The calculated results are obviously higher than that of the effective medium approximation assuming that graphite is distributed in isolation.It is suggested that the interconnected structure significantly enhances the overall thermal conductivity.Moreover,it is shown that high anisotropy of graphite thermal conductivity,high volume fraction of graphite,and small aspect ratio of flake graphite will cause the connectivity effects of graphite to more obviously improve the overall thermal conductivity.Higher graphite volume fraction,lower aspect ratio and higher matrix thermal conductivity are beneficial to obtain a high thermal conductivity gray cast iron.This work can provide guidance and reference for the development of high thermal conductivity gray cast iron and the design of high thermal conductivity composites with similar locally interconnected structures.
基金Supported by the National Natural Science Foundation of China(52077051).
文摘The generation of power semiconductor devicesdefinesa generation of power electronicconverters.The efficiency and switching speed of power devices continue to improve,leading to higher converter operating frequenciesand a continuous increase in power density.In particular,the emergence and widespread application of wide-bandgap power devices,such as silicon carbide and gallium nitride,have accelerated the process of high-frequencyconverter operations,significantly improving the power density of converters,whichstillhaveconsiderable room forimprovement.One significant change brought about by high-frequency operation of converters is the increased impact of parasiticson circuit operation.With the significant increase in the system switching frequency and the dv/dtanddi/dtof device switching,parasiticshave a greaterinfluenceon circuitoperation.Over the past decade,severalstudieson the analysisand modeling ofparasitics have been published for various devicesin converters,such as transformers,inductors,capacitors,and power devices;however,there is currently a lack of a comprehensive review to summarize the aboveresearch.Adetailed summary of parasiticsin power electronic convertersis included,providinga systematic understanding of past work and future prospects.
基金supported by the National Natural Science Foundation of China(No.52362024 and 22004106).
文摘Understanding the microstructure-property relationship from the microscopic and macroscopic perspectives,instead of semi-empirical rules,can facilitate the design of microcosmic morphology to adjust the impedance matching and dielectric loss of the carbon-based materials,which are still lacking so far.In this study,a clear correlation between microstructure and conduction loss was revealed in agarosederived carbon using a facile salt-etching strategy,in which ferric nitrate acted more as a morphology modifier for bulky carbon rather than a component regulator.Specifically,with the increasing amount of ferric nitrate,the original smooth bulky carbon was etched with caves,which gradually enlarged in size and depth and thus thinned in wall,and eventually transformed into a three-dimensional(3D)interconnected cellular structure,accompanied by a gradual increase in conductivity.Benefiting from the optimal impedance matching and strong conduction loss originating from the unique 3D cellular structure of agarose-derived carbon,AF-3 exhibited super-wide and strong absorption with an effective absorption bandwidth of 7.28 GHz(10.32-17.60 GHz,2.9 mm)and a minimum reflection loss of-46.6 dB(15.6 GHz,2.5 mm).This study establishes the relationship between microstructure,dielectric properties,and loss mechanism in carbon-based materials and also provides a new insight into the fine modulation of EMW-absorbing properties from morphological design.
基金This work was supported financially by the National Basic Research Program of China(973 Program,2012CB933600)National Natural Science Foundation of China(51572228,51172188).
文摘The macro-pore sizes of porous scaffold play a key role for regulating ectopic osteogenesis and angiogenesis but many researches ignored the influence of interconnection between macro-pores with different sizes.In order to accurately reveal the relationship between ectopic osteogenesis and macro-pore sizes in dorsal muscle and abdominal cavities of dogs,hydroxyapatite(HA)scaffolds with three different macro-pore sizes of 500–650,750–900 and 1100–1250 mm were prepared via sugar spheres-leaching process,which also had similar interconnecting structure determined by keeping the d/s ratio of interconnecting window diameter to macro-pore size constant.The permeability test showed that the seepage flow of fluid through the porous scaffolds increased with the increase of macro-pore sizes.The cell growth in three scaffolds was not affected by the macro-pore sizes.The in vivo ectopic implantation results indicated that the macro-pore sizes of HA scaffolds with the similar interconnecting structure have impact not only the speed of osteogenesis and angiogenesis but also the space distribution of newly formed bone.The scaffold with macro-pore sizes of 750–900 mm exhibited much faster angiogenesis and osteogenesis,and much more uniformly distribution of new bone than those with othermacro-pore sizes.This work illustrates the importance of a suitable macro-pore sizes in HA scaffolds with the similar interconnecting structure which provides the environment for ectopic osteogenesis and angiogenesis.
基金supported by the National Natural Science Foundation of China(82072400,82102211,52173117)the Natural Science Foundation of Jiangsu Province(BK20200001)+4 种基金the Natural Science Foundation of Shanghai(20ZR1402500)the Belt&Road Young Scientist Exchanges Project of Science and Technology Commission Foundation of Shanghai(20520741000)Ningbo 2025 Science and Technology Major Project(2019B10068)the Science and Technology Commission of Shanghai Municipality(20DZ2254900,20DZ2270800)the Fundamental Research Funds for the Central Universities,DHU Distinguished Young Professor Program(LZA2019001).
文摘Three-dimensional(3D)-printed scaffolds are widely used in tissue engineering to help regenerate critical-sized bone defects.However,conventional scaffolds possess relatively simple porous structures that limit the delivery of oxygen and nutrients to cells,leading to insufficient bone regeneration.Accordingly,in the present study,perfusable and permeable polycaprolactone scaffolds with highly interconnected hollow-pipe structures that mimic natural micro-vascular networks are prepared by an indirect onepot 3D-printing method.In vitro experiments demonstrate that hollow-pipe-structured(HPS)scaffolds promote cell attachment,proliferation,osteogenesis and angiogenesis compared to the normal non-hollow-pipe-structured scaffolds.Furthermore,in vivo studies reveal that HPS scaffolds enhance bone regeneration and vascularization in rabbit bone defects,as observed at 8 and 12weeks,respectively.Thus,the fabricated HPS scaffolds are promising candidates for the repair of critical-sized bone defects.
