This paper proposes a new step-by-step Chebyshev space-time spectral method to analyze the force vibration of functionally graded material structures.Although traditional space-time spectral methods can reduce the acc...This paper proposes a new step-by-step Chebyshev space-time spectral method to analyze the force vibration of functionally graded material structures.Although traditional space-time spectral methods can reduce the accuracy mismatch between tem-poral low-order finite difference and spatial high-order discre tization,the ir time collocation points must increase dramatically to solve highly oscillatory solutions of structural vibration,which results in a surge in computing time and a decrease in accuracy.To address this problem,we introduced the step-by-step idea in the space-time spectral method.The Chebyshev polynomials and Lagrange's equation were applied to derive discrete spatial goverming equations,and a matrix projection method was used to map the calculation results of prev ious steps as the initial conditions of the subsequent steps.A series of numerical experiments were carried out.The results of the proposed method were compared with those obtained by traditional space-time spectral methods,which showed that higher accuracy could be achieved in a shorter computation time than the latter in highly oscillatory cases.展开更多
Using the Skyrme density functional theory,potential energy surfaces of^(240)Pu with constraints on the axial quadrupole and octupole deformations(q_(20)and q_(30))were calculated.The volume-like and surface-like pair...Using the Skyrme density functional theory,potential energy surfaces of^(240)Pu with constraints on the axial quadrupole and octupole deformations(q_(20)and q_(30))were calculated.The volume-like and surface-like pairing forces,as well as a combination of these two forces,were used for the Hartree–Fock–Bogoliubov approximation.Variations in the least-energy fission path,fission barrier,pairing energy,total kinetic energy,scission line,and mass distribution of the fission fragments based on the different forms of the pairing forces were analyzed and discussed.The fission dynamics were studied based on the timedependent generator coordinate method plus the Gaussian overlap approximation.The results demonstrated a sensitivity of the mass and charge distributions of the fission fragments on the form of the pairing force.Based on the investigation of the neutron-induced fission of^(239)Pu,among the volume,mixed,and surface pairing forces,the mixed pairing force presented a good reproduction of the experimental data.展开更多
Electronic interactions of the Group 2A elements with magnesium have been studied through the dilute solid solutions in binary Mg-Ca,Mg-Sr and Mg-Ba systems.This investigation incorporated the difference in the‘Work ...Electronic interactions of the Group 2A elements with magnesium have been studied through the dilute solid solutions in binary Mg-Ca,Mg-Sr and Mg-Ba systems.This investigation incorporated the difference in the‘Work Function'(ΔWF)measured via Kelvin Probe Force Microscopy(KPFM),as a property directly affected by interatomic bond types,i.e.the electronic structure,nanoindentation measurements,and Stacking Fault Energy values reported in the literature.It was shown that the nano-hardness of the solid-solutionα-Mg phase changed in the order of Mg-Ca>Mg-Sr>Mg-Ba.Thus,it was shown,by also considering the nano-hardness levels,that SFE of a solid-solution is closely correlated with its‘Work Function'level.Nano-hardness measurements on the eutectics andΔWF difference between eutectic phases enabled an assessment of the relative bond strength and the pertinent electronic structures of the eutectics in the three alloys.Correlation withΔWF and at least qualitative verification of those computed SFE values with some experimental measurement techniques were considered important as those computational methods are based on zero Kelvin degree,relatively simple atomic models and a number of assumptions.As asserted by this investigation,if the results of measurement techniques can be qualitatively correlated with those of the computational methods,it can be possible to evaluate the electronic structures in alloys,starting from binary systems,going to ternary and then multi-elemental systems.Our investigation has shown that such a qualitative correlation is possible.After all,the SFE values are not treated as absolute values but rather become essential in comparative investigations when assessing the influences of alloying elements at a fundamental level,that is,free electron density distributions.Our study indicated that the principles of‘electronic metallurgy'in developing multi-elemental alloy systems can be followed via practical experimental methods,i.e.ΔWF measurements using KPFM and nanoindentation.展开更多
The noise feature of a single-mode class-A laser amplifier is investigated by solving the Maxwell–Bloch equations of motion in the presence of the fluctuation force of cavity Langevin.The aim is to calculate the simu...The noise feature of a single-mode class-A laser amplifier is investigated by solving the Maxwell–Bloch equations of motion in the presence of the fluctuation force of cavity Langevin.The aim is to calculate the simultaneous fluctuations that are superimposed on the amplitude and phase of the cavity electric field, as well as the atomic population inversion. The correlation function of these fluctuations yields the amplitude, phase, and spontaneous emission noise fluxes, respectively. The amplitude and spontaneous emission noise fluxes exhibit the Lorentzian profiles in both the below-threshold state and the injection-locking region of the above-threshold state. While noise is typically viewed negatively in science and engineering, this research highlights its positive role as a valuable tool for measuring the optical properties of a laser amplifier. For instance, the degree of first-order temporal coherence(DFOTC) is derived by taking the Fourier transform of the amplitude noise flux. The damping rate of DFOTC is associated with the coherence time of the light emitted by the laser amplifier. Furthermore, the uncertainty relation between noise bandwidth and coherence time is confirmed. Finally, it is demonstrated that the input pumping noise flux, together with the output amplitude and spontaneous emission noise fluxes, satisfy the principle of flux conservation.展开更多
Functionally graded materials(FGMs)are a novel class of composite materials that have attracted significant attention in the field of engineering due to their unique mechanical properties.This study aims to explore th...Functionally graded materials(FGMs)are a novel class of composite materials that have attracted significant attention in the field of engineering due to their unique mechanical properties.This study aims to explore the dynamic behaviors of an FGM stepped beam with different boundary conditions based on an efficient solving method.Under the assumptions of the Euler-Bernoulli beam theory,the governing differential equations of an individual FGM beam are derived with Hamilton’s principle and decoupled via the separation-of-variable approach.Then,the free and forced vibrations of the FGM stepped beam are solved with the transfer matrix method(TMM).Two models,i.e.,a three-level FGM stepped beam and a five-level FGM stepped beam,are considered,and their natural frequencies and mode shapes are presented.To demonstrate the validity of the method in this paper,the simulation results by ABAQUS are also given.On this basis,the detailed parametric analyses on the frequencies and dynamic responses of the three-level FGM stepped beam are carried out.The results show the accuracy and efficiency of the TMM.展开更多
As the Rural Revitalization Strategy is gradually implemented, China’s rural areas are set to have more diverse function requirements. This paper selects the Changsha-Zhuzhou-Xiangtan region(Chang-Zhu-Tan) consisting...As the Rural Revitalization Strategy is gradually implemented, China’s rural areas are set to have more diverse function requirements. This paper selects the Changsha-Zhuzhou-Xiangtan region(Chang-Zhu-Tan) consisting of 23 county-level units) as a case study and looks at its economic development, agricultural product supply, social security and ecological service functions during 1996–2016. It then constructs an index system to evaluate the temporal evolution of the region’s rural functions. SPSS 19.0 and DPS 7.05 software, as well as Pearson’s correlation coefficient analysis, system clustering, optimal segmentation of ordered samples and other methods, are used to study the evolution traits, regional differentiation characteristics and driving forces of rural functions in the region. The results show, first of all, that the overall evolution trend is increasing in functions with periodic characteristics, the key nodes being 2000 and 2008. Second, there is clear geographical differentiation in the evolution of rural functions. The economic development function shows rapid growth in the urban agglomeration’s center and relatively weak growth at the periphery;the agricultural product supply function and ecological service function are concentrated in county-level units with abundant cultivated and forest land;and the social security function displays similar geographical differentiation to the economic development function. Overall, there is an obvious discrepancy in the degree of development of rural functions among county-level units of the Changsha-Zhuzhou-Xiangtan urban agglomeration;the rural functions of the agglomeration and peripheral county-level units have different development traits;and county-level units display functional differentiation. Third, rural functions have evolved as a result of interactions between various factors, such as natural resources, socio-economic conditions and local transport conditions. The new driving forces caused by urbanization are ultimately leading the evolution of rural functions toward multi-functional comprehensive development.展开更多
The Green function on two-phase saturated medium by concentrated force has a broad and important use In seismology, seismic engineering, soil mechanics, geophysics, dynamic foundation theory and so on. According to th...The Green function on two-phase saturated medium by concentrated force has a broad and important use In seismology, seismic engineering, soil mechanics, geophysics, dynamic foundation theory and so on. According to the Green function on two-phase saturated medium by concentrated force in three-dimentional displacement field obtained by Ding Bo-yang et al., it gives out the Green function in two-dimensional displacement field by infinite integral method along x(3)-direction derived by De Hoop and Manolis. The method adopted in the thesis is simpler. The result will be simplified to the boundary element method of dynamic problem.展开更多
A lot of tests on ice forces on vertical cylindrical piles are conducted in the ice basin of ice laboratory in Tianjin University to identify the characteristics of ice forces on fixed platforms in the Bohai Gulf. A f...A lot of tests on ice forces on vertical cylindrical piles are conducted in the ice basin of ice laboratory in Tianjin University to identify the characteristics of ice forces on fixed platforms in the Bohai Gulf. A function of ice forces is simplified on basis of test data, and the characteristics of the ice forces including the amplitude of the force and the breaking frequency of the ice sheet is detailed by use of the Fast-Fourier-Transform method, The results show that the ice breaking frequency presents a linear relationship with the ratio of ice moving velocity to ice thickness at low velocities. At high velocities, the frequency remains constant with the increase of the ratio of ice moving velocity to ice thickness. These conclusions are compared those published in literature.展开更多
The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophagea...The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method.展开更多
The paper presents an improved plane layout for stabilizing piles based on a proposed piecewise function expression for the irregular driving force. Based on the specific morphological characteristics of a highway lan...The paper presents an improved plane layout for stabilizing piles based on a proposed piecewise function expression for the irregular driving force. Based on the specific morphological characteristics of a highway landslide, the piecewise function is used to calculate the irregular driving force by dividing the landslide into several sub-areas.Furthermore, the reasonable layout range and pile spacing can be obtained based on the piecewise function expression of the irregular driving force and on relevant research results of the plane layout for stabilizing piles. Therefore, an improved plane layout of stabilizing piles is presented in consideration of a piecewise function expression of the irregular driving force. A highway landslide located in eastern Guizhou Province, China, is analyzed as a case study using the proposed method. The results demonstrate that the theory presented in this paper provides improved economic benefits and can reduce the requirednumber of stabilizing piles by 28.6% compared with the conventional plane layout scheme.展开更多
Semiconductor/metal junctions are widely discussed in photocatalysis.However,there is a notable scarcity of systematic studies focusing on photogenerated charge carrier transfer in such junctions.Herein,CdS/Pt,CdS/Au,...Semiconductor/metal junctions are widely discussed in photocatalysis.However,there is a notable scarcity of systematic studies focusing on photogenerated charge carrier transfer in such junctions.Herein,CdS/Pt,CdS/Au,and CdS/Ag are synthesized to serve as model systems for investigating the charge carrier transfer in semiconductor/metal junctions.Kelvin probe force microscopy is employed to visualize the transfer of photogenerated carriers in these materials.The results show that the electron transfer behavior under illumination is related to the conduction band position of CdS and the Fermi level position of the metal.Moreover,Schottky junctions hinder the transfer of photogenerated electrons from CdS to Pt and Au,whereas ohmic contacts facilitate the transfer of photogenerated electrons from CdS to Ag.This work provides novel insights into the mechanisms governing the transfer of photogenerated carriers in semiconductor/metal junctions.展开更多
Respiratory diseases,especially asthma,are common in children.While spirometry contributes to asthma diagnosis and management in older children,it has a limited role in younger children whom are often unable to perfor...Respiratory diseases,especially asthma,are common in children.While spirometry contributes to asthma diagnosis and management in older children,it has a limited role in younger children whom are often unable to perform forced expiratory manoeuvre.The development of novel diagnostic methods which require minimal effort,such as forced oscillation technique(FOT)is,therefore,a welcome and promising addition.FOT involves applying external,small amplitude oscillations to the respiratory system during tidal breathing.Therefore,it requires minimal effort and cooperation.The FOT has the potential to facilitate asthma diagnosis and management in preschool children by faciliting the objective measurement of baseline lung function and airway reactivity in children unable to successfully perform spirometry.Traditionally the use of FOT was limited to specialised centres.However,the availability of commercial equipment resulted in its use both in research and in clinical practice.In this article,we review the available literature on the use of FOT in childhood asthma.The technical aspects of FOT are described followed by a discussion of its practical aspects in the clinical field including the measurement of baseline lung function and associated reference ranges,bronchodilator responsiveness and bronchial hyperresponsiveness.We also highlight the difficulties and limitations that might be encountered and future research directions.展开更多
Water Vapor Chemistry" as a new science was discovered and established from trace analysis in Gu’s laboratory(Gu, 1991; Gu et al., 1991). Gu’s Function shows that the trace metal ion concentration in water vapo...Water Vapor Chemistry" as a new science was discovered and established from trace analysis in Gu’s laboratory(Gu, 1991; Gu et al., 1991). Gu’s Function shows that the trace metal ion concentration in water vapor has positive correlation to"specific electron affinity constant"last ionization potential Iz/ion valence Z and negative correlation to ion volume V and coordination number N(Gu, 1994). Gu’s Func-tion C=f[(Iz/Z)/VN]of the bond parameter in water vapor chemistry corresponds to the potential energy function Z’ e2/r in the Schrodinger Equation of quantum chemistry. In different ions with the same 2+ charge, the ion concentration of water-water vapor transfer may be much different. This shows that the 2+ charge of different ions has different attractive force (hydration force). This different attractive force of the charge can be scaled with the relative energy or charge size from Gu’s Function.展开更多
Based on the solutions of the Green＇s function for a saturated porous medium obtained by the authors, and using transformation of axisymmetric coordinates, Sommerfeld integrals and superposition of the influence fiel...Based on the solutions of the Green＇s function for a saturated porous medium obtained by the authors, and using transformation of axisymmetric coordinates, Sommerfeld integrals and superposition of the influence field on a free surface, the authors have obtained displacement solutions of a saturated porous medium subjected to a torsional force in a half-space. The relationship curves of the displacement solutions and various parameters （permeability, frequency, etc.） under action of a unit of torque are also given in this paper. The results are consistent with previous Reissner＇s solutions, where a two-phase medium decays to a single-phase medium. The solution is useful in solving relevant dynamic problems of a two- phase saturated medium in engineering.展开更多
In this paper we study the forced oscillations of boundary value problems of a class of higher order functional partial differential equations.The principal tool is an everaging techniqe which enables one to establish...In this paper we study the forced oscillations of boundary value problems of a class of higher order functional partial differential equations.The principal tool is an everaging techniqe which enables one to establish oscillation in terms of related functional differential inequallities.展开更多
The negativity of Wigner function(WF)is one of the important symbols of non-classical properties of light field.Therefore,it is of great significance to study the evolution of WF in dissipative process.The evolution f...The negativity of Wigner function(WF)is one of the important symbols of non-classical properties of light field.Therefore,it is of great significance to study the evolution of WF in dissipative process.The evolution formula of WF in laser process under the action of linear resonance force is given by virtue of thermo entangled state representation and the technique of integration within an ordered product of operator.As its application,the evolution of WF of thermal field and that of single-photon-added coherent state are discussed.The results show that the WF of thermal field maintains its original character.On the other hand,the negative region size and the depth of negativity of WF of single-photon-added coherent state decrease until it vanishes with dissipation.This shows that the non-classical property of single-photon-added coherent state is weakened,until it disappears with dissipation time increasing.展开更多
Schrödinger equations are very common equations in physics and mathematics for nonlinear physics to model the dynamics of wave propagation in waveguides such as power lines, atomic chains, optical fibers, and eve...Schrödinger equations are very common equations in physics and mathematics for nonlinear physics to model the dynamics of wave propagation in waveguides such as power lines, atomic chains, optical fibers, and even in quantum mechanics. But all these equations are most often studied without worrying about what would happen if this equation were maintained, that is to say, had a second member synonymous with an external force. It is true that on a physical level, such equations can be considered as describing the generation of waves on a waveguide using an external force. However, the in-depth analysis of this aspect is not at the center of our reflection in this article, but for us, it is a question of proposing exact solutions to this type of equation and above all proposing the general form of the external force so that the obtaining exact solutions is possible.展开更多
基金supported by the Advance Research Project of Civil Aerospace Technology(Grant No.D020304)National Nat-ural Science Foundation of China(Grant Nos.52205257 and U22B2083).
文摘This paper proposes a new step-by-step Chebyshev space-time spectral method to analyze the force vibration of functionally graded material structures.Although traditional space-time spectral methods can reduce the accuracy mismatch between tem-poral low-order finite difference and spatial high-order discre tization,the ir time collocation points must increase dramatically to solve highly oscillatory solutions of structural vibration,which results in a surge in computing time and a decrease in accuracy.To address this problem,we introduced the step-by-step idea in the space-time spectral method.The Chebyshev polynomials and Lagrange's equation were applied to derive discrete spatial goverming equations,and a matrix projection method was used to map the calculation results of prev ious steps as the initial conditions of the subsequent steps.A series of numerical experiments were carried out.The results of the proposed method were compared with those obtained by traditional space-time spectral methods,which showed that higher accuracy could be achieved in a shorter computation time than the latter in highly oscillatory cases.
基金supported by the National Key R&D Program of China(No.2022YFA1602000)National Natural Science Foundation of China(Nos.12275081,U2067205,11790325,and U1732138)the Continuous-support Basic Scientific Research Project。
文摘Using the Skyrme density functional theory,potential energy surfaces of^(240)Pu with constraints on the axial quadrupole and octupole deformations(q_(20)and q_(30))were calculated.The volume-like and surface-like pairing forces,as well as a combination of these two forces,were used for the Hartree–Fock–Bogoliubov approximation.Variations in the least-energy fission path,fission barrier,pairing energy,total kinetic energy,scission line,and mass distribution of the fission fragments based on the different forms of the pairing forces were analyzed and discussed.The fission dynamics were studied based on the timedependent generator coordinate method plus the Gaussian overlap approximation.The results demonstrated a sensitivity of the mass and charge distributions of the fission fragments on the form of the pairing force.Based on the investigation of the neutron-induced fission of^(239)Pu,among the volume,mixed,and surface pairing forces,the mixed pairing force presented a good reproduction of the experimental data.
基金financial support for this work provided by Eski sehir Technical University Scientific Research Projects Unit with Grant Number 20DRP059support provided by the Turkish Ministry of Science,Industry and Technology under the SANTEZ Project 0286.STZ.2013±2。
文摘Electronic interactions of the Group 2A elements with magnesium have been studied through the dilute solid solutions in binary Mg-Ca,Mg-Sr and Mg-Ba systems.This investigation incorporated the difference in the‘Work Function'(ΔWF)measured via Kelvin Probe Force Microscopy(KPFM),as a property directly affected by interatomic bond types,i.e.the electronic structure,nanoindentation measurements,and Stacking Fault Energy values reported in the literature.It was shown that the nano-hardness of the solid-solutionα-Mg phase changed in the order of Mg-Ca>Mg-Sr>Mg-Ba.Thus,it was shown,by also considering the nano-hardness levels,that SFE of a solid-solution is closely correlated with its‘Work Function'level.Nano-hardness measurements on the eutectics andΔWF difference between eutectic phases enabled an assessment of the relative bond strength and the pertinent electronic structures of the eutectics in the three alloys.Correlation withΔWF and at least qualitative verification of those computed SFE values with some experimental measurement techniques were considered important as those computational methods are based on zero Kelvin degree,relatively simple atomic models and a number of assumptions.As asserted by this investigation,if the results of measurement techniques can be qualitatively correlated with those of the computational methods,it can be possible to evaluate the electronic structures in alloys,starting from binary systems,going to ternary and then multi-elemental systems.Our investigation has shown that such a qualitative correlation is possible.After all,the SFE values are not treated as absolute values but rather become essential in comparative investigations when assessing the influences of alloying elements at a fundamental level,that is,free electron density distributions.Our study indicated that the principles of‘electronic metallurgy'in developing multi-elemental alloy systems can be followed via practical experimental methods,i.e.ΔWF measurements using KPFM and nanoindentation.
文摘The noise feature of a single-mode class-A laser amplifier is investigated by solving the Maxwell–Bloch equations of motion in the presence of the fluctuation force of cavity Langevin.The aim is to calculate the simultaneous fluctuations that are superimposed on the amplitude and phase of the cavity electric field, as well as the atomic population inversion. The correlation function of these fluctuations yields the amplitude, phase, and spontaneous emission noise fluxes, respectively. The amplitude and spontaneous emission noise fluxes exhibit the Lorentzian profiles in both the below-threshold state and the injection-locking region of the above-threshold state. While noise is typically viewed negatively in science and engineering, this research highlights its positive role as a valuable tool for measuring the optical properties of a laser amplifier. For instance, the degree of first-order temporal coherence(DFOTC) is derived by taking the Fourier transform of the amplitude noise flux. The damping rate of DFOTC is associated with the coherence time of the light emitted by the laser amplifier. Furthermore, the uncertainty relation between noise bandwidth and coherence time is confirmed. Finally, it is demonstrated that the input pumping noise flux, together with the output amplitude and spontaneous emission noise fluxes, satisfy the principle of flux conservation.
基金the National Natural Science Foundation of China(Nos.12302007,12372006,and 12202109)the Specific Research Project of Guangxi for Research Bases and Talents(No.AD23026051)。
文摘Functionally graded materials(FGMs)are a novel class of composite materials that have attracted significant attention in the field of engineering due to their unique mechanical properties.This study aims to explore the dynamic behaviors of an FGM stepped beam with different boundary conditions based on an efficient solving method.Under the assumptions of the Euler-Bernoulli beam theory,the governing differential equations of an individual FGM beam are derived with Hamilton’s principle and decoupled via the separation-of-variable approach.Then,the free and forced vibrations of the FGM stepped beam are solved with the transfer matrix method(TMM).Two models,i.e.,a three-level FGM stepped beam and a five-level FGM stepped beam,are considered,and their natural frequencies and mode shapes are presented.To demonstrate the validity of the method in this paper,the simulation results by ABAQUS are also given.On this basis,the detailed parametric analyses on the frequencies and dynamic responses of the three-level FGM stepped beam are carried out.The results show the accuracy and efficiency of the TMM.
基金National Natural Science Foundation of China,No.41571168Key Project of Philosophy and Social Science Foundation of Hunan Province,No.18ZDB015
文摘As the Rural Revitalization Strategy is gradually implemented, China’s rural areas are set to have more diverse function requirements. This paper selects the Changsha-Zhuzhou-Xiangtan region(Chang-Zhu-Tan) consisting of 23 county-level units) as a case study and looks at its economic development, agricultural product supply, social security and ecological service functions during 1996–2016. It then constructs an index system to evaluate the temporal evolution of the region’s rural functions. SPSS 19.0 and DPS 7.05 software, as well as Pearson’s correlation coefficient analysis, system clustering, optimal segmentation of ordered samples and other methods, are used to study the evolution traits, regional differentiation characteristics and driving forces of rural functions in the region. The results show, first of all, that the overall evolution trend is increasing in functions with periodic characteristics, the key nodes being 2000 and 2008. Second, there is clear geographical differentiation in the evolution of rural functions. The economic development function shows rapid growth in the urban agglomeration’s center and relatively weak growth at the periphery;the agricultural product supply function and ecological service function are concentrated in county-level units with abundant cultivated and forest land;and the social security function displays similar geographical differentiation to the economic development function. Overall, there is an obvious discrepancy in the degree of development of rural functions among county-level units of the Changsha-Zhuzhou-Xiangtan urban agglomeration;the rural functions of the agglomeration and peripheral county-level units have different development traits;and county-level units display functional differentiation. Third, rural functions have evolved as a result of interactions between various factors, such as natural resources, socio-economic conditions and local transport conditions. The new driving forces caused by urbanization are ultimately leading the evolution of rural functions toward multi-functional comprehensive development.
文摘The Green function on two-phase saturated medium by concentrated force has a broad and important use In seismology, seismic engineering, soil mechanics, geophysics, dynamic foundation theory and so on. According to the Green function on two-phase saturated medium by concentrated force in three-dimentional displacement field obtained by Ding Bo-yang et al., it gives out the Green function in two-dimensional displacement field by infinite integral method along x(3)-direction derived by De Hoop and Manolis. The method adopted in the thesis is simpler. The result will be simplified to the boundary element method of dynamic problem.
基金This project is financially supported by the National Natural Science Foundation of China (Grant No. 59739170)
文摘A lot of tests on ice forces on vertical cylindrical piles are conducted in the ice basin of ice laboratory in Tianjin University to identify the characteristics of ice forces on fixed platforms in the Bohai Gulf. A function of ice forces is simplified on basis of test data, and the characteristics of the ice forces including the amplitude of the force and the breaking frequency of the ice sheet is detailed by use of the Fast-Fourier-Transform method, The results show that the ice breaking frequency presents a linear relationship with the ratio of ice moving velocity to ice thickness at low velocities. At high velocities, the frequency remains constant with the increase of the ratio of ice moving velocity to ice thickness. These conclusions are compared those published in literature.
基金Supported by Det Obelske Familiefond and Spar Nord Fonden
文摘The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method.
基金supported by the National Key R&D Program of China (2017YFC1501304)the National Natural Science Fund of China (No. 41472261)+1 种基金 the Key Technical Project of Shenzhen Science Technology Project (No. JSGG20160331154546471) the Open Fund of State Key Laboratory of Geohazard Prevention and Geoenviroment Protection (Grant No. SKLGP2017K017)
文摘The paper presents an improved plane layout for stabilizing piles based on a proposed piecewise function expression for the irregular driving force. Based on the specific morphological characteristics of a highway landslide, the piecewise function is used to calculate the irregular driving force by dividing the landslide into several sub-areas.Furthermore, the reasonable layout range and pile spacing can be obtained based on the piecewise function expression of the irregular driving force and on relevant research results of the plane layout for stabilizing piles. Therefore, an improved plane layout of stabilizing piles is presented in consideration of a piecewise function expression of the irregular driving force. A highway landslide located in eastern Guizhou Province, China, is analyzed as a case study using the proposed method. The results demonstrate that the theory presented in this paper provides improved economic benefits and can reduce the requirednumber of stabilizing piles by 28.6% compared with the conventional plane layout scheme.
基金supported by the National Key Research and Development Program of China(No.2022YFB3803600)the National Natural Science Foundation of China(Nos.22238009,51932007,U1905215,52073223,22278324,52272290,52173065,and 22202187)+2 种基金the Natural Science Foundation of Hubei Province of China(No.2022CFA001)the National Postdoctoral Program for Innovative Talents(No.BX2021275)the Project funded by China Postdoctoral Science Foundation(No.2022M712957).
文摘Semiconductor/metal junctions are widely discussed in photocatalysis.However,there is a notable scarcity of systematic studies focusing on photogenerated charge carrier transfer in such junctions.Herein,CdS/Pt,CdS/Au,and CdS/Ag are synthesized to serve as model systems for investigating the charge carrier transfer in semiconductor/metal junctions.Kelvin probe force microscopy is employed to visualize the transfer of photogenerated carriers in these materials.The results show that the electron transfer behavior under illumination is related to the conduction band position of CdS and the Fermi level position of the metal.Moreover,Schottky junctions hinder the transfer of photogenerated electrons from CdS to Pt and Au,whereas ohmic contacts facilitate the transfer of photogenerated electrons from CdS to Ag.This work provides novel insights into the mechanisms governing the transfer of photogenerated carriers in semiconductor/metal junctions.
文摘Respiratory diseases,especially asthma,are common in children.While spirometry contributes to asthma diagnosis and management in older children,it has a limited role in younger children whom are often unable to perform forced expiratory manoeuvre.The development of novel diagnostic methods which require minimal effort,such as forced oscillation technique(FOT)is,therefore,a welcome and promising addition.FOT involves applying external,small amplitude oscillations to the respiratory system during tidal breathing.Therefore,it requires minimal effort and cooperation.The FOT has the potential to facilitate asthma diagnosis and management in preschool children by faciliting the objective measurement of baseline lung function and airway reactivity in children unable to successfully perform spirometry.Traditionally the use of FOT was limited to specialised centres.However,the availability of commercial equipment resulted in its use both in research and in clinical practice.In this article,we review the available literature on the use of FOT in childhood asthma.The technical aspects of FOT are described followed by a discussion of its practical aspects in the clinical field including the measurement of baseline lung function and associated reference ranges,bronchodilator responsiveness and bronchial hyperresponsiveness.We also highlight the difficulties and limitations that might be encountered and future research directions.
文摘Water Vapor Chemistry" as a new science was discovered and established from trace analysis in Gu’s laboratory(Gu, 1991; Gu et al., 1991). Gu’s Function shows that the trace metal ion concentration in water vapor has positive correlation to"specific electron affinity constant"last ionization potential Iz/ion valence Z and negative correlation to ion volume V and coordination number N(Gu, 1994). Gu’s Func-tion C=f[(Iz/Z)/VN]of the bond parameter in water vapor chemistry corresponds to the potential energy function Z’ e2/r in the Schrodinger Equation of quantum chemistry. In different ions with the same 2+ charge, the ion concentration of water-water vapor transfer may be much different. This shows that the 2+ charge of different ions has different attractive force (hydration force). This different attractive force of the charge can be scaled with the relative energy or charge size from Gu’s Function.
基金National Natural Science Foundation of China Under Grant No.11172268
文摘Based on the solutions of the Green＇s function for a saturated porous medium obtained by the authors, and using transformation of axisymmetric coordinates, Sommerfeld integrals and superposition of the influence field on a free surface, the authors have obtained displacement solutions of a saturated porous medium subjected to a torsional force in a half-space. The relationship curves of the displacement solutions and various parameters （permeability, frequency, etc.） under action of a unit of torque are also given in this paper. The results are consistent with previous Reissner＇s solutions, where a two-phase medium decays to a single-phase medium. The solution is useful in solving relevant dynamic problems of a two- phase saturated medium in engineering.
文摘In this paper we study the forced oscillations of boundary value problems of a class of higher order functional partial differential equations.The principal tool is an everaging techniqe which enables one to establish oscillation in terms of related functional differential inequallities.
基金supported by the Natural Science Foundation of Fujian Province(No.2015J01020)
文摘The negativity of Wigner function(WF)is one of the important symbols of non-classical properties of light field.Therefore,it is of great significance to study the evolution of WF in dissipative process.The evolution formula of WF in laser process under the action of linear resonance force is given by virtue of thermo entangled state representation and the technique of integration within an ordered product of operator.As its application,the evolution of WF of thermal field and that of single-photon-added coherent state are discussed.The results show that the WF of thermal field maintains its original character.On the other hand,the negative region size and the depth of negativity of WF of single-photon-added coherent state decrease until it vanishes with dissipation.This shows that the non-classical property of single-photon-added coherent state is weakened,until it disappears with dissipation time increasing.
文摘Schrödinger equations are very common equations in physics and mathematics for nonlinear physics to model the dynamics of wave propagation in waveguides such as power lines, atomic chains, optical fibers, and even in quantum mechanics. But all these equations are most often studied without worrying about what would happen if this equation were maintained, that is to say, had a second member synonymous with an external force. It is true that on a physical level, such equations can be considered as describing the generation of waves on a waveguide using an external force. However, the in-depth analysis of this aspect is not at the center of our reflection in this article, but for us, it is a question of proposing exact solutions to this type of equation and above all proposing the general form of the external force so that the obtaining exact solutions is possible.
