Traditional procedures to treat vibrations of gyroscopic continua involve direct application of perturbation methods to a system with both a strong gyroscopic term and other weakly coupled terms.In this study,a gyrosc...Traditional procedures to treat vibrations of gyroscopic continua involve direct application of perturbation methods to a system with both a strong gyroscopic term and other weakly coupled terms.In this study,a gyroscopic modes decoupling method is used to obtain an equivalent system with decoupled gyroscopic modes having only weak couplings.Taking the axially moving string as an example,the instability boundaries in the vicinity of parametric resonances are detected using both the traditional coupled gyroscopic system and our system with decoupled gyroscopic modes,and the results are compared to show the advantages and disadvantages of each method.展开更多
To the Editor:Thoracic endovascular aortic repair(TEVAR)has been widely accepted as the first-line treatment when aortic repair is indicated.However,TEVAR is still limited by anatomic conditions in many circumstances,...To the Editor:Thoracic endovascular aortic repair(TEVAR)has been widely accepted as the first-line treatment when aortic repair is indicated.However,TEVAR is still limited by anatomic conditions in many circumstances,and the most common exclusion situations are inadequate proximal and/or distal landing zones when important branch vessels are involved.The incidence of insufficient distal landing zone in descending TEVAR ranges from 2.5%to 15.2%,and different approaches to extend it were described.[1]Hybrid surgery with combined TEVAR and open revascularization of visceral vessels has been employed from the early stage of endovascular aortic repair but it is associated with poor outcomes.展开更多
In this paper, the nonlinear transient dynamic response of functionally graded material （FGM） sandwich doubly curved shell with homogenous isotropic material core and functionally graded face sheet is analyzed using...In this paper, the nonlinear transient dynamic response of functionally graded material （FGM） sandwich doubly curved shell with homogenous isotropic material core and functionally graded face sheet is analyzed using a new displacement field on the basis of Reddy＇s third-order shear theory for the first time. The equivalent material properties for the FGM face sheet are assumed to obey the rule of simple power law function in the thickness direction. Based on Reddy＇s theory of higher shear deformation, a new displacement field is developed by introducing the secant function into transverse displacement. Four coupled nonlinear differential equations are obtained by applying Hamilton＇s principle and Galerkin method. It is assumed that the FGM sandwich doubly curved shell is subjected to step loading, air-blast loading, triangular loading, and sinusoidal loading, respectively. On the basis of double-precision variable- coefficient ordinary differential equation solver, a new program code in FORTRAN software is developed to solve the nonlinear transient dynamics of the system. The influences of core thickness, volume fraction, core-to-face sheet thickness ratio, width-to-thickness ratio and blast type on the transient response of the shell are discussed in detail through numerical simulation.展开更多
This paper deals with the nonlinear forced vibration of FGM rectangular plate with a boundary of two edges clamped opposite and the other two free. The plate is subjected to transversal and in-plane excitations. The p...This paper deals with the nonlinear forced vibration of FGM rectangular plate with a boundary of two edges clamped opposite and the other two free. The plate is subjected to transversal and in-plane excitations. The present research treats the material properties of the FGM plates as temperature-dependent and graded continuously throughout the thickness direction, following the volume fraction of the constituent materials according to the power law. The temperature is assumed to be constant in the plane and varied only in the thickness direction of the plate. In the framework of geometrical nonlinearity the plate is modeled and the equations of motion are obtained on Hamilton＇s principle. With the help of Galerkin discretization, the nonlinear ordinary differential equations describing transverse vibration of the plate are proposed. By the numerical method, the nonlinear dynamical responses of the FGM plate with two clamped opposite and two free edges are analyzed.展开更多
Wafer-scale synthesis of p-type TMD films is critical for its commercialization in next-generation electro/optoelectronics.In this work,wafer-scale intrinsic n-type WS_(2)films and in situ Nb-doped p-type WS_(2)films ...Wafer-scale synthesis of p-type TMD films is critical for its commercialization in next-generation electro/optoelectronics.In this work,wafer-scale intrinsic n-type WS_(2)films and in situ Nb-doped p-type WS_(2)films were synthesized through atomic layer deposition(ALD)on 8-inchα-Al_(2)O_(3)/Si wafers,2-inch sapphire,and 1 cm^(2)GaN substrate pieces.The Nb doping concentration was precisely controlled by altering cycle number of Nb precursor and activated by postannealing.WS_(2)n-FETs and Nb-doped p-FETs with different Nb concentrations have been fabricated using CMOS-compatible processes.X-ray photoelectron spectroscopy,Raman spectroscopy,and Hall measurements confirmed the effective substitutional doping with Nb.The on/off ratio and electron mobility of WS_(2)n-FET are as high as 105 and 6.85 cm^(2)V^(-1)s^(-1),respectively.In WS_(2)p-FET with 15-cycle Nb doping,the on/off ratio and hole mobility are 10 and 0.016 cm^(2)V^(-1)s^(-1),respectively.The p-n structure based on n-and p-type WS_(2)films was proved with a 10^(4)rectifying ratio.The realization of controllable in situ Nb-doped WS_(2)films paved a way for fabricating wafer-scale complementary WS_(2)FETs.展开更多
An educational intervention targeting medical students and aiming to develop skills useful to the writing of a health science research protocol over a short period of time has been developed in the Shanghai Jiao Tong ...An educational intervention targeting medical students and aiming to develop skills useful to the writing of a health science research protocol over a short period of time has been developed in the Shanghai Jiao Tong University School of Medicine. The methodology blending the principles of PBL and TBL is detailed and key issues of this implementation are discussed. Twenty-one students were enrolled in a research master degree and participated to three mandatory 180-minutes sessions. Beyond classical skills useful to solve a problem, this new intervention focused on the transformation of knowledge to create an authentic content, which is a feature of the project-based learning(PBL). The training process was designed according to team-based learning(TBL) procedure except that work sharing between groups and pooling resources and outcomes of each group allowed the construction of one final class original research project in the field of respiratory pharmacology. The combination of both learning methods allowed promoting individual and group accountability necessary to improve self-learning and the quality of the final joint project. The peer reviewing was an essential factor in creating the students' motivation and improving of team discussion. The grades individually assigned for skills and quality of the project by an external teacher suggested that key objectives of the intervention were reached. In conclusion, the educational intervention described in this paper appears as an appropriate method to develop specific skills necessary to write and discuss a research project within a research team.Further works are necessary to measure the degree of satisfaction of students and improvement of performance.展开更多
In this paper,the blade is assumed to be a rotating variable thickness cantilever twisted plate structure,and the natural vibrations of variable thickness cantilever twisted plate made of metal porous material are stu...In this paper,the blade is assumed to be a rotating variable thickness cantilever twisted plate structure,and the natural vibrations of variable thickness cantilever twisted plate made of metal porous material are studied.It is assumed that the thickness of the plate changes along spanwise direction and chordwise direction,respectively,and it changes in both directions.The classical thin shell theory,the first and second fundamental forms of surface and von Karman geometric relationship are employed to derive the total potential energy and kinetic energy of the cantilever twisted plate,in which the centrifugal force potential due to high rotational speed is included.Then,according to the Rayleigh-Ritz procedure and applying the polynomial functions which satisfy the cantilever boundary conditions,the dynamic system expressed by equations of motion is reduced to an eigenvalue problem.By numerical simulation,the frequency curves and the mode shapes of the twisted plate can be obtained to reveal the internal connection between natural vibration and the parameters.A series of comparison studies are performed to verify the accuracy of the present formulation and calculations,in which compared data come from experimental,finite element method and theoretical calculation,respectively.The influence of pre-twist angle,three different forms of thickness taper ratio and rotational speed on natural vibration,mode exchange and frequency veering phenomenon of the system is discussed in detail.In addition,the approach proposed here can efficiently extract analytical expressions of mode functions for rotating variable thickness cantilever twisted plate structures.展开更多
Using Reddy’s high-order shear theory for laminated plates and Hamilton’s principle, a nonlinear partial differential equation for the dynamics of a deploying cantilevered piezoelectric laminated composite plate, un...Using Reddy’s high-order shear theory for laminated plates and Hamilton’s principle, a nonlinear partial differential equation for the dynamics of a deploying cantilevered piezoelectric laminated composite plate, under the combined action of aerodynamic load and piezoelectric excitation, is introduced. Two-degree of freedom(DOF)nonlinear dynamic models for the time-varying coefficients describing the transverse vibration of the deploying laminate under the combined actions of a first-order aerodynamic force and piezoelectric excitation were obtained by selecting a suitable time-dependent modal function satisfying the displacement boundary conditions and applying second-order discretization using the Galerkin method. Using a numerical method, the time history curves of the deploying laminate were obtained, and its nonlinear dynamic characteristics,including extension speed and different piezoelectric excitations, were studied. The results suggest that the piezoelectric excitation has a clear effect on the change of the nonlinear dynamic characteristics of such piezoelectric laminated composite plates. The nonlinear vibration of the deploying cantilevered laminate can be effectively suppressed by choosing a suitable voltage and polarity.展开更多
Engineering synthetic vaccines is promising for improving the efficacy of cancer immunotherapy.One of the major challenges in the development of vaccines is achieving controllable codelivery of antigen and adjuvant to...Engineering synthetic vaccines is promising for improving the efficacy of cancer immunotherapy.One of the major challenges in the development of vaccines is achieving controllable codelivery of antigen and adjuvant to lymph nodes for maximizing the antitumor immune responses.To address this issue,we herein developed an innovative visualizable nanodisc vaccine based on ovalbumin(OVA)and short-stranded oligodeoxynucleotides containing unmethylated cytosine-phosphate-guanine(CpG)motifs.The nanovaccine was fabricated by covalently attaching CpG onto the surface of a nanodisc antigen formed upon self-assembly of amphiphilic molecular conjugates of OVA and cypate(Cy),a near-infrared(NIR)fluorescent dye,for noninvasively visualizing the delivery of the resulting nanovaccines.Systematic in vitro experiments demonstrated that the engineered nanovaccines can specifically locate to dendritic cells(DCs)via toll-like receptor 9 and membrane thiols,and then efficiently activate DCs.The animal experiments combining NIR fluorescence imaging with the lymphatic T-cell phenotype and key cytokine secretion analyses revealed that targeted lymphatic homing of the mature DCs and consequent priming of CD8^(+)T cells were enabled to initiate strong tumor-specific T-cell responses with robust immune memory effects.Thus,this study offers a visualizable platform for optimizing the efficacy of nanovaccines toward cancer immunotherapies.展开更多
The frequency veering of a metal porous rotating cantilever twisted plate with twist angle and stagger angle is investigated.Metal porous materials may have the characteristics of gradient or uniform distribution alon...The frequency veering of a metal porous rotating cantilever twisted plate with twist angle and stagger angle is investigated.Metal porous materials may have the characteristics of gradient or uniform distribution along the thickness direction.Based on the classical shell theory,considering the influence of centrifugal force produced by high-speed rotation,the free vibration equations of a rotating cantilever twisted plate are derived.Through the polynomial function and Rayleigh-Ritz method,the natural frequencies and mode shapes of the metal porous cantilever twisted plate in both static and rotating states are derived.The accuracy of the present theory and calculation results is confirmed by a comparison between them and the results available from the literature and those obtained from Abaqus.The influences of the thickness ratio,porosity,twist angle,stagger angle and rotational velocity on the frequency veering and mode shape shift of the rotating cantilever twisted plate with porous material under three different distributions are analyzed.It should be mentioned that the frequency veering accompanied by mode shape shift occurs in both static and dynamic states.展开更多
In recent years,geographical information systems have been employed in a wide variety of application domains,and as a result many research efforts are being devoted to those upcoming problems.Geospatial data security,...In recent years,geographical information systems have been employed in a wide variety of application domains,and as a result many research efforts are being devoted to those upcoming problems.Geospatial data security,especially access control,has attracted increased research interests within the academic community.The tendency towards sharing and interoperability of geospatial data and applications makes it common to acquire and integrate geospatial data from multiple organisations to accomplish a complex task.Meanwhile,many organisations have the requirement for securing access to possessed sensitive or proprietary geospatial data.In this heterogeneous and distributed environment,consistent access control functionality is crucial to promote controlled accessibility.As an extension of general access control mechanisms in the IT domain,the mechanism for geospatial data access control has its own requirements and characteristics of granularity and geospatial logic.In this paper,we address several fundamental aspects concerning the design and implementation of an access control system for geospatial data,including the classification,requirements,authorisation models,storage structures and management approaches for authorisation rules,matching and decision-making algorithms between authorisation rules and access requests,and its policy enforcement mechanisms.This paper also presents a system framework for realising access control functionality for geospatial data,and explain access control procedures in detail.展开更多
Pesticide use in peri-urban areas afects the urban enviroment and public health,and reducing the use may present food security isues for urban dwellers.In this study,we explore how a muiallyadopted goal of a 20%reduet...Pesticide use in peri-urban areas afects the urban enviroment and public health,and reducing the use may present food security isues for urban dwellers.In this study,we explore how a muiallyadopted goal of a 20%reduetion in pesticide use could be achieved,along with local food security and environmental implica-tions,for Shanghai located in the densely populated East China.A regional Shanghai Agricultural Sector Model inorporating district-and technology-varying crop budgets,was developed to simulate the efects of pesticide reduction policy.Here we find that achieving the reduction goal had the largest implications in districts with high pesticide use totals and intensities,potentially reducing pesticide non point source pollution in the Yangtze River Estuary and Dianshan Lake;the production levels of rice and leafy vegetables would be most afected;and adopting machinery that allows more precise pesticide application modulates these results.Moreover,imposing the requlrements at the district-level caused more severe local food security concerns,and less environmental benefits.Furthermore,a closed Shanghai's agricultural economy would subtantally enlarge the regional het-erogeneity in the above-mentioaned outcomes.Exploring the ffects of a quantity control policy on current-use pesticides at diferent aggregation levels has important implications for regulating the use of agrochemicals.展开更多
Wafer-scale synthesis of p-type TMD films is critical for its commercialization in next-generation electro/optoelectronics.In this work,wafer-scale intrinsic n-type WS_(2)films and in situ Nb-doped p-type WS_(2)films ...Wafer-scale synthesis of p-type TMD films is critical for its commercialization in next-generation electro/optoelectronics.In this work,wafer-scale intrinsic n-type WS_(2)films and in situ Nb-doped p-type WS_(2)films were synthesized through atomic layer deposition(ALD)on 8-inchα-Al_(2)O_(3)/Si wafers,2-inch sapphire,and 1 cm^(2)GaN substrate pieces.The Nb doping concentration was precisely controlled by altering cycle number of Nb precursor and activated by postannealing.WS_(2)n-FETs and Nb-doped p-FETs with different Nb concentrations have been fabricated using CMOS-compatible processes.X-ray photoelectron spectroscopy,Raman spectroscopy,and Hall measurements confirmed the effective substitutional doping with Nb.The on/off ratio and electron mobility of WS_(2)n-FET are as high as 105 and 6.85 cm^(2)V^(-1)s^(-1),respectively.In WS_(2)p-FET with 15-cycle Nb doping,the on/off ratio and hole mobility are 10 and 0.016 cm^(2)V^(-1)s^(-1),respectively.The p-n structure based on n-and p-type WS_(2)films was proved with a 10^(4) rectifying ratio.The realization of controllable in situ Nb-doped WS_(2)films paved a way for fabricating wafer-scale complementary WS_(2)FETs.展开更多
Anonlocal two-fluid formulation has been constructed for describing lowerhybrid drift instabilities in current-sheet configuration with a finite guide magnetic field in the context of magnetic reconnection.As a benchm...Anonlocal two-fluid formulation has been constructed for describing lowerhybrid drift instabilities in current-sheet configuration with a finite guide magnetic field in the context of magnetic reconnection.As a benchmark and verification,a class of unstable modes with multiple eigenstates are found by numerical solutions with guide field turned off.It is found that the most unstable modes are the electrostatic,short-wavelength perturbations in the lower-hybrid frequency range,with wave functions localized at the edge of the current sheet where the density gradient reaches its maximum.It is also found that there exist electrostatic modes located near the center of the current sheet where the current density is maximum.These modes are lowfrequency,long-wavelength perturbations.Attempts will bemade to compare the current results with those from kinetic theory in the near future since the validity of the fluid theory ultimately needs to be checked with the more fundamental kinetic theory.展开更多
There has recently been a dramatic renewal of interest in hadron spectroscopy and charm physics. This renaissance has been driven in part by the discovery of a plethora of charmonium-like XYZ states at BESⅢ and B fac...There has recently been a dramatic renewal of interest in hadron spectroscopy and charm physics. This renaissance has been driven in part by the discovery of a plethora of charmonium-like XYZ states at BESⅢ and B factories, and the observation of an intriguing proton-antiproton threshold enhancement and the possibly related X(1835) meson state at BESⅢ, as well as the threshold measurements of charm mesons and charm baryons. We present a detailed survey of the important topics in tau-charm physics and hadron physics that can be further explored at BESⅢ during the remaining operation period of BEPCⅡ. This survey will help in the optimization of the data-taking plan over the coming years, and provides physics motivation for the possible upgrade of BEPCⅡ to higher luminosity.展开更多
基金the National Natural Science Foundation of China(Grants 11772009,11672007)the Beijing Municipal Natural Science Foundation(Grant 3172003).
文摘Traditional procedures to treat vibrations of gyroscopic continua involve direct application of perturbation methods to a system with both a strong gyroscopic term and other weakly coupled terms.In this study,a gyroscopic modes decoupling method is used to obtain an equivalent system with decoupled gyroscopic modes having only weak couplings.Taking the axially moving string as an example,the instability boundaries in the vicinity of parametric resonances are detected using both the traditional coupled gyroscopic system and our system with decoupled gyroscopic modes,and the results are compared to show the advantages and disadvantages of each method.
文摘To the Editor:Thoracic endovascular aortic repair(TEVAR)has been widely accepted as the first-line treatment when aortic repair is indicated.However,TEVAR is still limited by anatomic conditions in many circumstances,and the most common exclusion situations are inadequate proximal and/or distal landing zones when important branch vessels are involved.The incidence of insufficient distal landing zone in descending TEVAR ranges from 2.5%to 15.2%,and different approaches to extend it were described.[1]Hybrid surgery with combined TEVAR and open revascularization of visceral vessels has been employed from the early stage of endovascular aortic repair but it is associated with poor outcomes.
基金the support from the National Natural Science Foundation of China(NNSFC) through Grant No.11472056Beijing Key Laboratory Open Research Project KF20171123202
文摘In this paper, the nonlinear transient dynamic response of functionally graded material （FGM） sandwich doubly curved shell with homogenous isotropic material core and functionally graded face sheet is analyzed using a new displacement field on the basis of Reddy＇s third-order shear theory for the first time. The equivalent material properties for the FGM face sheet are assumed to obey the rule of simple power law function in the thickness direction. Based on Reddy＇s theory of higher shear deformation, a new displacement field is developed by introducing the secant function into transverse displacement. Four coupled nonlinear differential equations are obtained by applying Hamilton＇s principle and Galerkin method. It is assumed that the FGM sandwich doubly curved shell is subjected to step loading, air-blast loading, triangular loading, and sinusoidal loading, respectively. On the basis of double-precision variable- coefficient ordinary differential equation solver, a new program code in FORTRAN software is developed to solve the nonlinear transient dynamics of the system. The influences of core thickness, volume fraction, core-to-face sheet thickness ratio, width-to-thickness ratio and blast type on the transient response of the shell are discussed in detail through numerical simulation.
基金supported by the National Natural Science Foundation of China(NNSFC)(Nos.10972026,11272063,11072008 and 11290152)the Funding Project for Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality(PHRIHLB)the Science Foundation of Beijing Municipal Education Commission(No.cit&tcd201304112)
文摘This paper deals with the nonlinear forced vibration of FGM rectangular plate with a boundary of two edges clamped opposite and the other two free. The plate is subjected to transversal and in-plane excitations. The present research treats the material properties of the FGM plates as temperature-dependent and graded continuously throughout the thickness direction, following the volume fraction of the constituent materials according to the power law. The temperature is assumed to be constant in the plane and varied only in the thickness direction of the plate. In the framework of geometrical nonlinearity the plate is modeled and the equations of motion are obtained on Hamilton＇s principle. With the help of Galerkin discretization, the nonlinear ordinary differential equations describing transverse vibration of the plate are proposed. By the numerical method, the nonlinear dynamical responses of the FGM plate with two clamped opposite and two free edges are analyzed.
基金supported by the NSFC(62004044 and 61904033)by State Key Laboratory of ASIC&System(2021MS004)This research was partially supported by the National Science Foundation through the Center for Dynamics and Control of Materials:an NSF MRSEC under Cooperative Agreement No.DMR-1720595。
文摘Wafer-scale synthesis of p-type TMD films is critical for its commercialization in next-generation electro/optoelectronics.In this work,wafer-scale intrinsic n-type WS_(2)films and in situ Nb-doped p-type WS_(2)films were synthesized through atomic layer deposition(ALD)on 8-inchα-Al_(2)O_(3)/Si wafers,2-inch sapphire,and 1 cm^(2)GaN substrate pieces.The Nb doping concentration was precisely controlled by altering cycle number of Nb precursor and activated by postannealing.WS_(2)n-FETs and Nb-doped p-FETs with different Nb concentrations have been fabricated using CMOS-compatible processes.X-ray photoelectron spectroscopy,Raman spectroscopy,and Hall measurements confirmed the effective substitutional doping with Nb.The on/off ratio and electron mobility of WS_(2)n-FET are as high as 105 and 6.85 cm^(2)V^(-1)s^(-1),respectively.In WS_(2)p-FET with 15-cycle Nb doping,the on/off ratio and hole mobility are 10 and 0.016 cm^(2)V^(-1)s^(-1),respectively.The p-n structure based on n-and p-type WS_(2)films was proved with a 10^(4)rectifying ratio.The realization of controllable in situ Nb-doped WS_(2)films paved a way for fabricating wafer-scale complementary WS_(2)FETs.
文摘An educational intervention targeting medical students and aiming to develop skills useful to the writing of a health science research protocol over a short period of time has been developed in the Shanghai Jiao Tong University School of Medicine. The methodology blending the principles of PBL and TBL is detailed and key issues of this implementation are discussed. Twenty-one students were enrolled in a research master degree and participated to three mandatory 180-minutes sessions. Beyond classical skills useful to solve a problem, this new intervention focused on the transformation of knowledge to create an authentic content, which is a feature of the project-based learning(PBL). The training process was designed according to team-based learning(TBL) procedure except that work sharing between groups and pooling resources and outcomes of each group allowed the construction of one final class original research project in the field of respiratory pharmacology. The combination of both learning methods allowed promoting individual and group accountability necessary to improve self-learning and the quality of the final joint project. The peer reviewing was an essential factor in creating the students' motivation and improving of team discussion. The grades individually assigned for skills and quality of the project by an external teacher suggested that key objectives of the intervention were reached. In conclusion, the educational intervention described in this paper appears as an appropriate method to develop specific skills necessary to write and discuss a research project within a research team.Further works are necessary to measure the degree of satisfaction of students and improvement of performance.
基金the financial support of National Natural Science Foundation of China through grant nos.11872127,11832002,11732005Qin Xin Talents Cultivation ProgramBeijing Information Science&Technology University QXTCP A201901。
文摘In this paper,the blade is assumed to be a rotating variable thickness cantilever twisted plate structure,and the natural vibrations of variable thickness cantilever twisted plate made of metal porous material are studied.It is assumed that the thickness of the plate changes along spanwise direction and chordwise direction,respectively,and it changes in both directions.The classical thin shell theory,the first and second fundamental forms of surface and von Karman geometric relationship are employed to derive the total potential energy and kinetic energy of the cantilever twisted plate,in which the centrifugal force potential due to high rotational speed is included.Then,according to the Rayleigh-Ritz procedure and applying the polynomial functions which satisfy the cantilever boundary conditions,the dynamic system expressed by equations of motion is reduced to an eigenvalue problem.By numerical simulation,the frequency curves and the mode shapes of the twisted plate can be obtained to reveal the internal connection between natural vibration and the parameters.A series of comparison studies are performed to verify the accuracy of the present formulation and calculations,in which compared data come from experimental,finite element method and theoretical calculation,respectively.The influence of pre-twist angle,three different forms of thickness taper ratio and rotational speed on natural vibration,mode exchange and frequency veering phenomenon of the system is discussed in detail.In addition,the approach proposed here can efficiently extract analytical expressions of mode functions for rotating variable thickness cantilever twisted plate structures.
基金supported by the National Natural Science Foundation of China (Grants 11402126, 11502122, and 11290152)the Scientific Research Foundation of the Inner Mongolia University of Technology (Grant ZD201410)
文摘Using Reddy’s high-order shear theory for laminated plates and Hamilton’s principle, a nonlinear partial differential equation for the dynamics of a deploying cantilevered piezoelectric laminated composite plate, under the combined action of aerodynamic load and piezoelectric excitation, is introduced. Two-degree of freedom(DOF)nonlinear dynamic models for the time-varying coefficients describing the transverse vibration of the deploying laminate under the combined actions of a first-order aerodynamic force and piezoelectric excitation were obtained by selecting a suitable time-dependent modal function satisfying the displacement boundary conditions and applying second-order discretization using the Galerkin method. Using a numerical method, the time history curves of the deploying laminate were obtained, and its nonlinear dynamic characteristics,including extension speed and different piezoelectric excitations, were studied. The results suggest that the piezoelectric excitation has a clear effect on the change of the nonlinear dynamic characteristics of such piezoelectric laminated composite plates. The nonlinear vibration of the deploying cantilevered laminate can be effectively suppressed by choosing a suitable voltage and polarity.
基金supported by National Natural Science Foundation of China(nos.21874097 and 12075164)National Key Research Program of China(no.2018YFA0208800)+5 种基金Suzhou Administration of Science and Technology(no.sys2018021)Jiangsu Province’s Natural Science Foundation(no.SBK2020041529)Pre-Research Foundation of the Second Affiliated Hospital of Soochow University(no.SDFEYBS1906)the Scientific Research Program for Young Talents of China National Nuclear CorporationA Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the support by the Youth Innovation Promotion Association,Chinese Academy of Sciences(no.2020010).
文摘Engineering synthetic vaccines is promising for improving the efficacy of cancer immunotherapy.One of the major challenges in the development of vaccines is achieving controllable codelivery of antigen and adjuvant to lymph nodes for maximizing the antitumor immune responses.To address this issue,we herein developed an innovative visualizable nanodisc vaccine based on ovalbumin(OVA)and short-stranded oligodeoxynucleotides containing unmethylated cytosine-phosphate-guanine(CpG)motifs.The nanovaccine was fabricated by covalently attaching CpG onto the surface of a nanodisc antigen formed upon self-assembly of amphiphilic molecular conjugates of OVA and cypate(Cy),a near-infrared(NIR)fluorescent dye,for noninvasively visualizing the delivery of the resulting nanovaccines.Systematic in vitro experiments demonstrated that the engineered nanovaccines can specifically locate to dendritic cells(DCs)via toll-like receptor 9 and membrane thiols,and then efficiently activate DCs.The animal experiments combining NIR fluorescence imaging with the lymphatic T-cell phenotype and key cytokine secretion analyses revealed that targeted lymphatic homing of the mature DCs and consequent priming of CD8^(+)T cells were enabled to initiate strong tumor-specific T-cell responses with robust immune memory effects.Thus,this study offers a visualizable platform for optimizing the efficacy of nanovaccines toward cancer immunotherapies.
基金The authors acknowledge the financial support of National Natural Science Foundation of China(grant nos.11872127,11832002,and 11732005)the Qin Xin Talents Cultivation Program,Beijing Information Science&Technology University(QXTCP A201901)the Project of High-level Innovative Team Building Plan for Beijing Municipal Colleges and Universities(No.IDHT20180513).
文摘The frequency veering of a metal porous rotating cantilever twisted plate with twist angle and stagger angle is investigated.Metal porous materials may have the characteristics of gradient or uniform distribution along the thickness direction.Based on the classical shell theory,considering the influence of centrifugal force produced by high-speed rotation,the free vibration equations of a rotating cantilever twisted plate are derived.Through the polynomial function and Rayleigh-Ritz method,the natural frequencies and mode shapes of the metal porous cantilever twisted plate in both static and rotating states are derived.The accuracy of the present theory and calculation results is confirmed by a comparison between them and the results available from the literature and those obtained from Abaqus.The influences of the thickness ratio,porosity,twist angle,stagger angle and rotational velocity on the frequency veering and mode shape shift of the rotating cantilever twisted plate with porous material under three different distributions are analyzed.It should be mentioned that the frequency veering accompanied by mode shape shift occurs in both static and dynamic states.
基金This work is supported by Project 2007AA120502,sponsored by NHTRDPCthe National High Technology Research and Development Program of China.
文摘In recent years,geographical information systems have been employed in a wide variety of application domains,and as a result many research efforts are being devoted to those upcoming problems.Geospatial data security,especially access control,has attracted increased research interests within the academic community.The tendency towards sharing and interoperability of geospatial data and applications makes it common to acquire and integrate geospatial data from multiple organisations to accomplish a complex task.Meanwhile,many organisations have the requirement for securing access to possessed sensitive or proprietary geospatial data.In this heterogeneous and distributed environment,consistent access control functionality is crucial to promote controlled accessibility.As an extension of general access control mechanisms in the IT domain,the mechanism for geospatial data access control has its own requirements and characteristics of granularity and geospatial logic.In this paper,we address several fundamental aspects concerning the design and implementation of an access control system for geospatial data,including the classification,requirements,authorisation models,storage structures and management approaches for authorisation rules,matching and decision-making algorithms between authorisation rules and access requests,and its policy enforcement mechanisms.This paper also presents a system framework for realising access control functionality for geospatial data,and explain access control procedures in detail.
基金supported by the National Natural Science Foundation of China(Grants No.71803133 and 72088101)the Shanghai Pujiang Talent Program(Grant No.17PJC068)and the Fundamental Research Funds for the Central Universities through Shanghai Jiao Tong University(Grant No.WF220428008).
文摘Pesticide use in peri-urban areas afects the urban enviroment and public health,and reducing the use may present food security isues for urban dwellers.In this study,we explore how a muiallyadopted goal of a 20%reduetion in pesticide use could be achieved,along with local food security and environmental implica-tions,for Shanghai located in the densely populated East China.A regional Shanghai Agricultural Sector Model inorporating district-and technology-varying crop budgets,was developed to simulate the efects of pesticide reduction policy.Here we find that achieving the reduction goal had the largest implications in districts with high pesticide use totals and intensities,potentially reducing pesticide non point source pollution in the Yangtze River Estuary and Dianshan Lake;the production levels of rice and leafy vegetables would be most afected;and adopting machinery that allows more precise pesticide application modulates these results.Moreover,imposing the requlrements at the district-level caused more severe local food security concerns,and less environmental benefits.Furthermore,a closed Shanghai's agricultural economy would subtantally enlarge the regional het-erogeneity in the above-mentioaned outcomes.Exploring the ffects of a quantity control policy on current-use pesticides at diferent aggregation levels has important implications for regulating the use of agrochemicals.
基金supported by the NSFC(62004044 and 61904033)and by State Key Laboratory of ASIC&System(2021MS004)This research was partially supported by the National Science Foundation through the Center for Dynamics and Control of Materials:an NSF MRSEC under Cooperative Agreement No.DMR-1720595.
文摘Wafer-scale synthesis of p-type TMD films is critical for its commercialization in next-generation electro/optoelectronics.In this work,wafer-scale intrinsic n-type WS_(2)films and in situ Nb-doped p-type WS_(2)films were synthesized through atomic layer deposition(ALD)on 8-inchα-Al_(2)O_(3)/Si wafers,2-inch sapphire,and 1 cm^(2)GaN substrate pieces.The Nb doping concentration was precisely controlled by altering cycle number of Nb precursor and activated by postannealing.WS_(2)n-FETs and Nb-doped p-FETs with different Nb concentrations have been fabricated using CMOS-compatible processes.X-ray photoelectron spectroscopy,Raman spectroscopy,and Hall measurements confirmed the effective substitutional doping with Nb.The on/off ratio and electron mobility of WS_(2)n-FET are as high as 105 and 6.85 cm^(2)V^(-1)s^(-1),respectively.In WS_(2)p-FET with 15-cycle Nb doping,the on/off ratio and hole mobility are 10 and 0.016 cm^(2)V^(-1)s^(-1),respectively.The p-n structure based on n-and p-type WS_(2)films was proved with a 10^(4) rectifying ratio.The realization of controllable in situ Nb-doped WS_(2)films paved a way for fabricating wafer-scale complementary WS_(2)FETs.
基金The authors acknowledge fruitful discussions with Liu Chen,and Yu Lin.This work was supported by Department of Energy(DOE)Grants No.DE-FG02-07ER54916(UC Irvine)and DE-FG02-05ER54826(Auburn University)NSF Grant No.ATM-0449606Los Alamos National Laboratory Subcontract No.50219-001-07.
文摘Anonlocal two-fluid formulation has been constructed for describing lowerhybrid drift instabilities in current-sheet configuration with a finite guide magnetic field in the context of magnetic reconnection.As a benchmark and verification,a class of unstable modes with multiple eigenstates are found by numerical solutions with guide field turned off.It is found that the most unstable modes are the electrostatic,short-wavelength perturbations in the lower-hybrid frequency range,with wave functions localized at the edge of the current sheet where the density gradient reaches its maximum.It is also found that there exist electrostatic modes located near the center of the current sheet where the current density is maximum.These modes are lowfrequency,long-wavelength perturbations.Attempts will bemade to compare the current results with those from kinetic theory in the near future since the validity of the fluid theory ultimately needs to be checked with the more fundamental kinetic theory.
基金Supported in part by National Key Basic Research Program of China (2015CB856700)National Natural Science Foundation of China (NSFC) (11335008,11425524, 11625523, 11635010, 11735014, 11822506, 11935018)+18 种基金the Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Programthe CAS Center for Excellence in Particle Physics (CCEPP)Joint Large-Scale Scientific Facility Funds of the NSFC and CAS (U1532257, U1532258, U1732263)CAS Key Research Program of Frontier Science (QYZDJ-SSW-SLH003, QYZDJ-SSW-SLH040)100 Talents Program of CASCAS PIFIthe Thousand Talents Program of ChinaIN-PAC and Shanghai Key Laboratory for Particle Physics and CosmologyGerman Research Foundation DFG under Contracts NosCollaborative Research Center CRC 1044, FOR 2359Istituto Nazionale di Fisica Nucleare, ItalyKoninklijke Nederlandse Akademie van Wetenschappen (KNAW) (530-4CDP03)Ministry of Development of Turkey (DPT2006K-120470)National Science and Technology fundThe Knut and Alice Wallenberg Foundation (Sweden) (2016.0157)The Swedish Research CouncilU. S. Department of Energy (DE-FG02-05ER41374, DESC-0010118, DE-SC-0012069)University of Groningen (Ru G) and the Helmholtzzentrum fuer Schwerionenforschung Gmb H (GSI), Darmstadtthe Russian Ministry of Science and Higher Education (14.W03.31.0026).
文摘There has recently been a dramatic renewal of interest in hadron spectroscopy and charm physics. This renaissance has been driven in part by the discovery of a plethora of charmonium-like XYZ states at BESⅢ and B factories, and the observation of an intriguing proton-antiproton threshold enhancement and the possibly related X(1835) meson state at BESⅢ, as well as the threshold measurements of charm mesons and charm baryons. We present a detailed survey of the important topics in tau-charm physics and hadron physics that can be further explored at BESⅢ during the remaining operation period of BEPCⅡ. This survey will help in the optimization of the data-taking plan over the coming years, and provides physics motivation for the possible upgrade of BEPCⅡ to higher luminosity.
