Inverse synthetic aperture radar (ISAR) image can be represented and reconstructed by sparse recovery (SR) approaches. However, the existing SR algorithms, which are used for ISAR imaging, have suffered from high comp...Inverse synthetic aperture radar (ISAR) image can be represented and reconstructed by sparse recovery (SR) approaches. However, the existing SR algorithms, which are used for ISAR imaging, have suffered from high computational cost and poor imaging quality under a low signal to noise ratio (SNR) condition. This paper proposes a fast decoupled ISAR imaging method by exploiting the inherent structural sparse information of the targets. Firstly, the ISAR imaging problem is decoupled into two sub-problems. One is range direction imaging and the other is azimuth direction focusing. Secondly, an efficient two-stage SR method is proposed to obtain higher resolution range profiles by using jointly sparse information. Finally, the residual linear Bregman iteration via fast Fourier transforms (RLBI-FFT) is proposed to perform the azimuth focusing on low SNR efficiently. Theoretical analysis and simulation results show that the proposed method has better performence to efficiently implement higher-resolution ISAR imaging under the low SNR condition.展开更多
Shape memory photonic crystals(SMPCs)are smart composite materials with changeable structural color integrated by shape memory polymer and photonic crystals.SMPC can produce one or more temporary shapes through nanosc...Shape memory photonic crystals(SMPCs)are smart composite materials with changeable structural color integrated by shape memory polymer and photonic crystals.SMPC can produce one or more temporary shapes through nanoscale deformation,memorizing current states.SMPC can be recovered to their original shapes or some intermediate states under external stimuli,accompanied by the variation of structural color.As porous carriers with built-in sensing properties,SMPCs promoted the interdisciplinary development of nanophotonic technology in materials science,environmental engineering,biomedicine,chemical engineering,and mechanics.Herein,the recent progress on multifunctional SMPCs and practical applications,including traditional and cold programmable SMPCs,is summarized and discussed.The primary concern is shape programming at the nanoscale that has demonstrated numerous attractive functions,including smart sensing,ink-free printing,solvent detection,reprogrammable gradient wetting,and controllable bubble transportation,under variations of the surface nanostructure.It aims to figure out the nanoscale shape memory effects on structural color conversion and additional performance,inspiring the fabrication of the next generation of SMPCs.Finally,perspectives on future research directions and applications are also presented.It is believed that multifunctional SMPCs are powerful nanophotonic tools for the interdisciplinary development of numerous disciplines in the future.展开更多
Waxy crude oil emulsion has thixotropic properties at the temperature near gel point,which is a macromechanical characterization of the structure failure and recovery of waxy crude oil emulsion.In this paper,the thixo...Waxy crude oil emulsion has thixotropic properties at the temperature near gel point,which is a macromechanical characterization of the structure failure and recovery of waxy crude oil emulsion.In this paper,the thixotropic behaviors of waxy crude oil emulsion near gel point were studied using hysteresis loop formed by stress linear increase and decrease,as well as the structural recovery characteristics.The influence of the loading conditions and water content on the thixotropy of waxy crude oil emulsion were analyzed with hysteresis loop area.The concept of"structural recovery"was introduced to study the degree of structural recovery after different stewing,and influencing factors were taken into account.Results have shown that for waxy crude oil emulsion,the failure to fully restore of the structure after lysis is the cause of the formation of hysteresis loop,and the loading conditions will not affect the strength of thixotropy and the degree of structural recovery.Additionally,the dispersed phase droplets weaken the thixotropy and structure recovery characteristics of waxy crude oil emulsion,and the greater the water content,the weaker the thixotropy.The findings can help to better understand the safe and economic operation of waxy crude oil-water pipeline transportation.展开更多
Recently,biomaterials for cartilage regeneration has been intensively investigated.However,the development of scaffolds that capture regenerated cartilage with biomechanical and structural recovery has rarely been rep...Recently,biomaterials for cartilage regeneration has been intensively investigated.However,the development of scaffolds that capture regenerated cartilage with biomechanical and structural recovery has rarely been reported.To address this challenge,platelet-rich plasma(PRP)-based cartilage constructs with a well-orchestrated symphony of cellular,biochemical and biomechanical elements were prepared by simultaneously employing chondrogenic progenitor cells(CPCs)as a cell source,optimizing platelet concentration,and adding an enzyme-ion activator.It was shown that this triple-optimized PRP+CPC construct possessed increased biomechanical properties and suitable biochemical signals.The following in vitro study demonstrated that the triple-optimized PRP+CPC constructs generated cartilage-like tissue with higher expression levels of chondrogenic-specific markers,more deposition of cartilage-specific extracellular matrix(ECM),and greater biomechanical values than those of the other constructs.Twelve weeks after the construct was implanted in a cartilage defect in vivo,histological analysis,qPCR,and biomechanical tests collectively showed that the triple-optimized constructs yielded a more chondrocyte-like cell phenotype with a higher synthesis of Col-Ⅱand aggrecan.More importantly,the triple-optimized constructs facilitated cartilage regeneration with better biomechanical recovery than that of the other constructs.These results demonstrate the efficacy of the triple-optimization strategy and highlight the simplicity and potency of this PRP+CPC construct for cartilage regeneration.展开更多
基金supported by the National Natural Science Foundation of China(61671469)
文摘Inverse synthetic aperture radar (ISAR) image can be represented and reconstructed by sparse recovery (SR) approaches. However, the existing SR algorithms, which are used for ISAR imaging, have suffered from high computational cost and poor imaging quality under a low signal to noise ratio (SNR) condition. This paper proposes a fast decoupled ISAR imaging method by exploiting the inherent structural sparse information of the targets. Firstly, the ISAR imaging problem is decoupled into two sub-problems. One is range direction imaging and the other is azimuth direction focusing. Secondly, an efficient two-stage SR method is proposed to obtain higher resolution range profiles by using jointly sparse information. Finally, the residual linear Bregman iteration via fast Fourier transforms (RLBI-FFT) is proposed to perform the azimuth focusing on low SNR efficiently. Theoretical analysis and simulation results show that the proposed method has better performence to efficiently implement higher-resolution ISAR imaging under the low SNR condition.
基金supported by the Program of the National Natural Science Foundation of China(Nos.22238002 and 22208047)China Postdoctoral Science Foundation(No.2022M720639)+2 种基金Dalian High-level Talents Innovation Support Project(No.2019RD06)the Liaoning Revitalization Talent Program(No.1801006)Research and Innovation Team Project of Dalian University of Technology(No.DUT2022TB10).
文摘Shape memory photonic crystals(SMPCs)are smart composite materials with changeable structural color integrated by shape memory polymer and photonic crystals.SMPC can produce one or more temporary shapes through nanoscale deformation,memorizing current states.SMPC can be recovered to their original shapes or some intermediate states under external stimuli,accompanied by the variation of structural color.As porous carriers with built-in sensing properties,SMPCs promoted the interdisciplinary development of nanophotonic technology in materials science,environmental engineering,biomedicine,chemical engineering,and mechanics.Herein,the recent progress on multifunctional SMPCs and practical applications,including traditional and cold programmable SMPCs,is summarized and discussed.The primary concern is shape programming at the nanoscale that has demonstrated numerous attractive functions,including smart sensing,ink-free printing,solvent detection,reprogrammable gradient wetting,and controllable bubble transportation,under variations of the surface nanostructure.It aims to figure out the nanoscale shape memory effects on structural color conversion and additional performance,inspiring the fabrication of the next generation of SMPCs.Finally,perspectives on future research directions and applications are also presented.It is believed that multifunctional SMPCs are powerful nanophotonic tools for the interdisciplinary development of numerous disciplines in the future.
基金supported by the Natural Science Foundation of Heilongjiang Province(Grant No.LH2020E015)the General Project of Natural Science Research in Jiangsu Universities(Grant No.20KJB440004)+1 种基金the science and technology program of Changzhou University(Grant No.ZMF18020303 and ZMF18020304)the science and technology program of Jiangsu Key Laboratory of Oil and Gas Storage&Transportation Technology(Grant No.CDYQCY201903,CDYQCY201904 and CDYQCY202003)。
文摘Waxy crude oil emulsion has thixotropic properties at the temperature near gel point,which is a macromechanical characterization of the structure failure and recovery of waxy crude oil emulsion.In this paper,the thixotropic behaviors of waxy crude oil emulsion near gel point were studied using hysteresis loop formed by stress linear increase and decrease,as well as the structural recovery characteristics.The influence of the loading conditions and water content on the thixotropy of waxy crude oil emulsion were analyzed with hysteresis loop area.The concept of"structural recovery"was introduced to study the degree of structural recovery after different stewing,and influencing factors were taken into account.Results have shown that for waxy crude oil emulsion,the failure to fully restore of the structure after lysis is the cause of the formation of hysteresis loop,and the loading conditions will not affect the strength of thixotropy and the degree of structural recovery.Additionally,the dispersed phase droplets weaken the thixotropy and structure recovery characteristics of waxy crude oil emulsion,and the greater the water content,the weaker the thixotropy.The findings can help to better understand the safe and economic operation of waxy crude oil-water pipeline transportation.
基金the National Natural Science Foundation of China(81871771,81572159)the Beijing Natural Sciences Grants(7182123,7191010).
文摘Recently,biomaterials for cartilage regeneration has been intensively investigated.However,the development of scaffolds that capture regenerated cartilage with biomechanical and structural recovery has rarely been reported.To address this challenge,platelet-rich plasma(PRP)-based cartilage constructs with a well-orchestrated symphony of cellular,biochemical and biomechanical elements were prepared by simultaneously employing chondrogenic progenitor cells(CPCs)as a cell source,optimizing platelet concentration,and adding an enzyme-ion activator.It was shown that this triple-optimized PRP+CPC construct possessed increased biomechanical properties and suitable biochemical signals.The following in vitro study demonstrated that the triple-optimized PRP+CPC constructs generated cartilage-like tissue with higher expression levels of chondrogenic-specific markers,more deposition of cartilage-specific extracellular matrix(ECM),and greater biomechanical values than those of the other constructs.Twelve weeks after the construct was implanted in a cartilage defect in vivo,histological analysis,qPCR,and biomechanical tests collectively showed that the triple-optimized constructs yielded a more chondrocyte-like cell phenotype with a higher synthesis of Col-Ⅱand aggrecan.More importantly,the triple-optimized constructs facilitated cartilage regeneration with better biomechanical recovery than that of the other constructs.These results demonstrate the efficacy of the triple-optimization strategy and highlight the simplicity and potency of this PRP+CPC construct for cartilage regeneration.
