For the accurate extraction of cavity decay time, a selection of data points is supplemented to the weighted least square method. We derive the expected precision, accuracy and computation cost of this improved method...For the accurate extraction of cavity decay time, a selection of data points is supplemented to the weighted least square method. We derive the expected precision, accuracy and computation cost of this improved method, and examine these performances by simulation. By comparing this method with the nonlinear least square fitting (NLSF) method and the linear regression of the sum (LRS) method in derivations and simulations, we find that this method can achieve the same or even better precision, comparable accuracy, and lower computation cost. We test this method by experimental decay signals. The results are in agreement with the ones obtained from the nonlinear least square fitting method.展开更多
We study the theoretical effect of k-cubic (i.e, cubic-in-momentum) Dresselhaus spin-orbit coupling on the decay time of persistent spin helix states in semiconductor two-dimensional electron gases. We show that the...We study the theoretical effect of k-cubic (i.e, cubic-in-momentum) Dresselhaus spin-orbit coupling on the decay time of persistent spin helix states in semiconductor two-dimensional electron gases. We show that the decay time of persistent spin helix states may be suppressed substantially by k-cubic Dresselhaus spin-orbit coupling, and after taking the effect of k-cubic Dresselhaus spin-orbit interaction into account, the theoretical results obtained accord both qualitatively and quantitatively with other recent experimental results.展开更多
We developed a procedure to prepare luminescent LiYF_(4):Yb/LiYF_(4) and LiYF_(4):Yb,Er/LiYF_(4) core/shell nanocrystals with a size of approximately 40 nm revealing luminescence decay times of the dopant ions that ap...We developed a procedure to prepare luminescent LiYF_(4):Yb/LiYF_(4) and LiYF_(4):Yb,Er/LiYF_(4) core/shell nanocrystals with a size of approximately 40 nm revealing luminescence decay times of the dopant ions that approach those of high-quality laser crystals of LiYF_(4):Yb(Yb:YLF)and LiYF_(4):Yb,Er(Yb,Er:YLF)with identical doping concentrations.As the luminescence decay times of Yb^(3+)and Er^(3+)are known to be very sensitive to the presence of quenchers,the long decay times of the core/shell nanocrystals indicate a very low number of defects in the core particles and at the core/shell interfaces.This improvement in the performance was achieved by introducing two important modifications in the commonly used oleic acid based synthesis.First,the shell was prepared via a newly developed method characterized by a very low nucleation rate for particles of pure LiYF_(4) shell material.Second,anhydrous acetates were used as precursors and additional drying steps were applied to reduce the incorporation of OH−in the crystal lattice,known to quench the emission of Yb^(3+)ions.Excitation power density(P)-dependent absolute measurements of the upconversion luminescence quantum yield(ΦUC)of LiYF_(4):Yb,Er/LiYF_(4) core/shell particles reveal a maximum value of 1.25%at P of 180 W·cm^(−2).Although lower than the values reported for NaYF4:18%Yb,2%Er core/shell nanocrystals with comparable sizes,theseΦUC values are the highest reported so far for LiYF_(4):18%Yb,2%Er/LiYF_(4) nanocrystals without additional dopants.Further improvements may nevertheless be possible by optimizing the dopant concentrations in the LiYF_(4) nanocrystals.展开更多
A novel series of Ce^3+-doped Yb3 Al(5-x)GaxO(12)(x = 0, 1,2, 3,4, 5) powders of ytterbium aluminum gallium garnets were synthesized by high temperature solid-state reaction in a carbon reducing atmosphere. The...A novel series of Ce^3+-doped Yb3 Al(5-x)GaxO(12)(x = 0, 1,2, 3,4, 5) powders of ytterbium aluminum gallium garnets were synthesized by high temperature solid-state reaction in a carbon reducing atmosphere. The ytterbium aluminum garnets were characterized by X-ray powder diffraction, UV-Vis diffuse reflectance spectra, photoluminescence spectra and decay curves. Moreover, the substitution effect for the Al^3+ sites with Ga^3+ in 0.5 at%Ce:Yb3 Al(5-x)GaxO(12)(x = 0,1, 2, 3, 4, 5) garnets were discussed. With the increase of Ga^3+ ion concentration, the visible absorption peaks within 400-450 nm have blue shift phenomenon,while the absorption peaks in the range of 330-350 nm and the absorption band edge red shifts.Furthermore, the short decay times are very short with less than 10 ns due to the Yb^3+ + Ce^3+→ Yb^2+ + Ce^4+ electron transfer reaction.展开更多
In this review article, we present recent developments and improvements in magnetic resonance sounding (MRS), a newly established geophysical exploration method that provides unique information about hydrogeophysica...In this review article, we present recent developments and improvements in magnetic resonance sounding (MRS), a newly established geophysical exploration method that provides unique information about hydrogeophysical properties due to its direct sensitivity to hydrogen protons and proton dynamics. Starting with the most sophisticated and complete MRS formulation, we give a detailed view on how to solve the equation, i.e., inverting exactly for all model parameters: water content, decay time, and resistivity. Giving a short review of general inversion schemes used in geophysics, the special properties of MRS inversion are evaluated and the development of MRS inversion over recent years is shown. We present the extension of MRS to magnetic resonance tomography (MRT), i.e., the extension to two-dimensional investigations and appropriate inversions. Finally, we address restrictions, limitations, and inconsistencies as well as future developments.展开更多
The photoplethysmogram(PPG) of a pulse wave,similar in appearance to the arterial blood pressure(ABP) waveform,contains rich information about the cardiovascular system.The decay time constant RC,equal to the product ...The photoplethysmogram(PPG) of a pulse wave,similar in appearance to the arterial blood pressure(ABP) waveform,contains rich information about the cardiovascular system.The decay time constant RC,equal to the product of peripheral resistance R and total arterial compliance C,is a meaningful cardiovascular model parameter in vascular assessment.Using or ameliorating the existing ABP methods does not achieve a satisfactory estimation of RC from the PPG volume pulse(VRC).Thus,a novel non-iterative shape method(NSM) of evaluating VRC is introduced in this paper.The mathematic expression between a novel,readily available morphological parameter called the area difference ratio(ADR) and VRC was established.As it was difficult to calculate VRC from the complicated expression analytically,we recommend estimating it using a piecewise linear interpolation criterion.Also,since the effect of the PPG magnitude is eliminated in the calculation of ADR,precaliberation or normalization is dispensable in the NSM.Results of human experiments indicated that the NSM was computationally efficient,and the simulation experiments confirmed that the NSM was theoretically available for ABP.展开更多
In this paper, we first show the global existence, uniqueness and regularity of weak solutions for the hyperbolic magnetohydrodynamics(MHD) equations in R^3. Then we establish that the solutions with initial data belo...In this paper, we first show the global existence, uniqueness and regularity of weak solutions for the hyperbolic magnetohydrodynamics(MHD) equations in R^3. Then we establish that the solutions with initial data belonging to H^m(R^3) ∩ L^1(R^3) have the following time decay rate:║▽~mu(x, t) ║~2+║ ▽~mb(x, t)║~ 2+ ║▽^(m+1)u(x, t)║~ 2+ ║▽^(m+1)b(x, t) ║~2≤ c(1 + t)^(-3/2-m)for large t, where m = 0, 1.展开更多
In this paper, we show the existence and regularity of mild solutions depending on the small initial data in Besov spaces to the fractional porous medium equation. When 1 < <em>α</em> ≤ 2, we prove gl...In this paper, we show the existence and regularity of mild solutions depending on the small initial data in Besov spaces to the fractional porous medium equation. When 1 < <em>α</em> ≤ 2, we prove global well-posedness for initial data <img src="Edit_b7b43d4c-00d8-49d6-9066-97151fb5c337.bmp" alt="" /> with 1 ≤ <em>p</em> < ∞, 1 ≤ <em>q</em> ≤ ∞, and analyticity of solutions with 1 < <em>p</em> < ∞, 1 ≤ <em>q</em> ≤ ∞. In particular, we also proved that when <em>α</em> = 1, both <em>u</em> and <img src="Edit_a5af0853-8adc-4a08-b8a2-b9a70ea0f409.bmp" alt="" /> belong to <img src="Edit_03a932cc-aa58-4568-83ad-f16416cc7b71.bmp" alt="" />. We solve this equation through the contraction mapping method based on Littlewood-Paley theory and Fourier multiplier. Furthermore, we can get time decay estimates of global solutions in Besov spaces, which is <img src="Edit_083986e9-4e1c-4494-ac5d-a7d30a12df97.bmp" alt="" /> as <em>t</em> → ∞.展开更多
This study investigates the effect of the magnetic field on the transient density of excess minority charge carriers in the base of a series-connected vertical junction silicon solar cell. The solar cell is presented ...This study investigates the effect of the magnetic field on the transient density of excess minority charge carriers in the base of a series-connected vertical junction silicon solar cell. The solar cell is presented in open circuit transient operation. The magnetic field through the Laplace force which deflects the photogenerated carriers from their initial trajectory towards the lateral surfaces reducing their mobility, diffusion and conduction, will certainly influence the decay time of the transient regime. The transient density of excess minority carriers in the base is a sum of infinite terms whose decay time of the different harmonics is studied.展开更多
In this paper,we study the global existence and decay rates of strong solutions to the three dimensional compressible Phan-Thein-Tanner model.By a refined energy method,we prove the global existence under the assumpti...In this paper,we study the global existence and decay rates of strong solutions to the three dimensional compressible Phan-Thein-Tanner model.By a refined energy method,we prove the global existence under the assumption that the H^(3) norm of the initial data is small,but that the higher order derivatives can be large.If the initial data belong to homogeneous Sobolev spaces or homogeneous Besov spaces,we obtain the time decay rates of the solution and its higher order spatial derivatives.Moreover,we also obtain the usual L^(p)-L^(2)(1≤p≤2)type of the decay rate without requiring that the Lpnorm of initial data is small.展开更多
In this paper, we study the non-isentropic compressible magnetohydrodynamic system with a time periodic external force in R^n. Under the condition that the optimal time decay rates are obtained by spectral analysis, w...In this paper, we study the non-isentropic compressible magnetohydrodynamic system with a time periodic external force in R^n. Under the condition that the optimal time decay rates are obtained by spectral analysis, we show that the existence, uniqueness and time-asymptotic stability of time periodic solutions when the space dimension n 〉 5. Our proof is based on a combination of the energy method and the contraction mapping theorem.展开更多
We consider the global existence and decay of integral solutions to the parabolic-parabolic Keller-Segel system in d-dimension.On the one hand,by Banach fixed point theorem and some properties of heat kernel,we prove ...We consider the global existence and decay of integral solutions to the parabolic-parabolic Keller-Segel system in d-dimension.On the one hand,by Banach fixed point theorem and some properties of heat kernel,we prove the local existence and the global existence of integral solutions for the different initial data under some conditions that involve the size of the initial data.On the other hand,in the case of global solutions,we obtain their optimal time decay by Gronwall’s lemma.展开更多
In this paper,it is proved that the weak solution to the Cauchy problem for the scalar viscous conservation law,with nonlinear viscosity,different far field states and periodic perturbations,not only exists globally i...In this paper,it is proved that the weak solution to the Cauchy problem for the scalar viscous conservation law,with nonlinear viscosity,different far field states and periodic perturbations,not only exists globally in time,but also converges towards the viscous shock wave of the corresponding Riemann problem as time goes to infinity.Furthermore,the decay rate is shown.The proof is given by a technical energy method.展开更多
Oxygen/glucose deprivation (OGD) has been widely used as an in vitro model of focal ischemia, where the blood flow is severely reduced and neurons rapidly die. However, adjacent to the focal region is ‘penumbra', ...Oxygen/glucose deprivation (OGD) has been widely used as an in vitro model of focal ischemia, where the blood flow is severely reduced and neurons rapidly die. However, adjacent to the focal region is ‘penumbra', where residual blood flow remains oxygen and glucose supplies are at low levels. To model this pathological genesis, we developed a partial OGD (pOGD) protocol in a rat brain slice. This model met two requirements: oxygen was partially deprived and glucose was reduced in the perfusion buffer. Therefore we investigated the effect of pOGD on gama-aminobutyric acid (GABAA) receptor-mediated inhibitory postsynaptic currents (IPSCs) in CA1 neurons of a hippocampal slice through whole-cell patch-clamp technique. We found that the amplitude and decay time of IPSCs were increased immediately during pOGD treatment. And the enhancement of IPSCs amplitude resulted from an increase of the synaptic conductance without a significant change in the reversal potential of chloride. These results suggested that the nervous system could increase inhibitory neurotransmission to offset excitation by homeostasis mechanisms during the partial oxygen and glucose attack.展开更多
Upconversion (UC) phosphor Tm3+ doped YF3 nano-erystals were prepared by hydrothermal method under different conditions and characterized by Field Transmission electron microscopy (TEM), Scanning electron microsc...Upconversion (UC) phosphor Tm3+ doped YF3 nano-erystals were prepared by hydrothermal method under different conditions and characterized by Field Transmission electron microscopy (TEM), Scanning electron microscopy (SEM) and X-ray diffraction (XRD). Their UC luminescence properties were studied by fluorescence spectrophotometer with 980 nm diode laser excitation, and impact of different grain sizes and morphology on the UC luminescence intensity was discussed. The fluorescence decay lifetime was calculated by Multi-exponential function fitting method. Results show that UC emission intensity was enhanced with the reduction of grain size, and the decay lifetime is 0.60 us.展开更多
The optical properties of LaCl3:Ce crystal are reported in this paper. Optical transmission spectrum, photoluminescence and time resolved photoluminescence spectra at different temperatures are investigated. It is fo...The optical properties of LaCl3:Ce crystal are reported in this paper. Optical transmission spectrum, photoluminescence and time resolved photoluminescence spectra at different temperatures are investigated. It is found that optical transmittance is as high as 80% between 320 nm and 600 nm, and no obvious absorption band is found in this region. Emission intensity and decay time of photoluminescence are quite stable with the change of the temperature between 80 K and 500 K. No thermal quenching is present up to 500 K, and decay time keeps at 17±2 ns. With the increase of the temperature, the whole emission bands and excitation bands present broadening and overlapping, leading to the strengthening of re-absorption of the Ce^3+ emission, which makes the emission spectra have a red shift trend.展开更多
A series of aAl5O12:Ce (YAG:Ce) phosphors doped with different Si4+ concentrations is prepared by solid-state reaction. The temperature dependent characteristics of luminescent spectrum and decay time of Ce3+ ar...A series of aAl5O12:Ce (YAG:Ce) phosphors doped with different Si4+ concentrations is prepared by solid-state reaction. The temperature dependent characteristics of luminescent spectrum and decay time of Ce3+ are investigated. With Si4+ doped, the emission spectrum shows a blue shift clue to a decrease of the splitting of 5d levels of Ce3+ ion. The thermal stability is greatly improved by adding Si4+ because the activation energy AE increases from 0.1836 eV to 0.2401 eV. The study of the decay times against temperature for various doping concentrations of Si4+ shows that the calculated nonradiative decay rate is affected by Si4+ substitution. The results are explained by the configurational coordinate diagram.展开更多
This is a survey paper on the study of compressible Navier-Stokes-Poisson equations. The emphasis is on the long time behavior of global solutions to multi-dimensional compressible Navier-Stokes-Poisson equations, and...This is a survey paper on the study of compressible Navier-Stokes-Poisson equations. The emphasis is on the long time behavior of global solutions to multi-dimensional compressible Navier-Stokes-Poisson equations, and the optimal decay rates for both unipolar and bipolar compressible Navier-Stokes-Poisson equations are discussed.展开更多
The compressible non-isentropic bipolar Navier-Stokes-Poisson (BNSP) sys- tem is investigated in R3 in the present paper, and the optimal time decay rates of global strong solution are shown. For initial data being ...The compressible non-isentropic bipolar Navier-Stokes-Poisson (BNSP) sys- tem is investigated in R3 in the present paper, and the optimal time decay rates of global strong solution are shown. For initial data being a perturbation of equilibrium state in Hl(R3) (R3) for 1 〉 4 and s E (0, 1], it is shown that the density and temperature for each charged particle (like electron or ion) decay at the same optimal rate (1 + t)-3/4, but the momentum for each particle decays at the optimal rate (1 + t)-1/4-3/2 which is slower than the rate (1 + t)-3/4-3/2 for the compressible Navier-Stokes (NS) equations [19] for same initial data. However, the total momentum tends to the constant state at the rate (1 +t)-3/4 as well, due to the interplay interaction of charge particles which counteracts the influence of electric field.展开更多
In this paper, we consider the Vlasov-Maxwell-Fokker-Planck system with relativistic transport in the whole space. The global solutions to this system near the relativistic Maxwellian are constructed and the optimal t...In this paper, we consider the Vlasov-Maxwell-Fokker-Planck system with relativistic transport in the whole space. The global solutions to this system near the relativistic Maxwellian are constructed and the optimal time decay rate of global solutions are also obtained by an approach by combining the compensating function and energy method.展开更多
基金supported by the Preeminent Youth Fund of Sichuan Province,China(Grant No.2012JQ0012)the National Natural Science Foundation of China(Grant Nos.11173008,10974202,and 60978049)the National Key Scientific and Research Equipment Development Project of China(Grant No.ZDYZ2013-2)
文摘For the accurate extraction of cavity decay time, a selection of data points is supplemented to the weighted least square method. We derive the expected precision, accuracy and computation cost of this improved method, and examine these performances by simulation. By comparing this method with the nonlinear least square fitting (NLSF) method and the linear regression of the sum (LRS) method in derivations and simulations, we find that this method can achieve the same or even better precision, comparable accuracy, and lower computation cost. We test this method by experimental decay signals. The results are in agreement with the ones obtained from the nonlinear least square fitting method.
基金Project supported by the National Natural Science Foundation of China (Grant No.10874049)
文摘We study the theoretical effect of k-cubic (i.e, cubic-in-momentum) Dresselhaus spin-orbit coupling on the decay time of persistent spin helix states in semiconductor two-dimensional electron gases. We show that the decay time of persistent spin helix states may be suppressed substantially by k-cubic Dresselhaus spin-orbit coupling, and after taking the effect of k-cubic Dresselhaus spin-orbit interaction into account, the theoretical results obtained accord both qualitatively and quantitatively with other recent experimental results.
基金We thank the German Science Foundation DFG for financial support(grants RE 1203/18-1 and HA 1649/7-1).
文摘We developed a procedure to prepare luminescent LiYF_(4):Yb/LiYF_(4) and LiYF_(4):Yb,Er/LiYF_(4) core/shell nanocrystals with a size of approximately 40 nm revealing luminescence decay times of the dopant ions that approach those of high-quality laser crystals of LiYF_(4):Yb(Yb:YLF)and LiYF_(4):Yb,Er(Yb,Er:YLF)with identical doping concentrations.As the luminescence decay times of Yb^(3+)and Er^(3+)are known to be very sensitive to the presence of quenchers,the long decay times of the core/shell nanocrystals indicate a very low number of defects in the core particles and at the core/shell interfaces.This improvement in the performance was achieved by introducing two important modifications in the commonly used oleic acid based synthesis.First,the shell was prepared via a newly developed method characterized by a very low nucleation rate for particles of pure LiYF_(4) shell material.Second,anhydrous acetates were used as precursors and additional drying steps were applied to reduce the incorporation of OH−in the crystal lattice,known to quench the emission of Yb^(3+)ions.Excitation power density(P)-dependent absolute measurements of the upconversion luminescence quantum yield(ΦUC)of LiYF_(4):Yb,Er/LiYF_(4) core/shell particles reveal a maximum value of 1.25%at P of 180 W·cm^(−2).Although lower than the values reported for NaYF4:18%Yb,2%Er core/shell nanocrystals with comparable sizes,theseΦUC values are the highest reported so far for LiYF_(4):18%Yb,2%Er/LiYF_(4) nanocrystals without additional dopants.Further improvements may nevertheless be possible by optimizing the dopant concentrations in the LiYF_(4) nanocrystals.
基金Project supported by National Natural Science Foundation of China(11475242,51272263)K.C.Wong Magna Fund in Ningbo University
文摘A novel series of Ce^3+-doped Yb3 Al(5-x)GaxO(12)(x = 0, 1,2, 3,4, 5) powders of ytterbium aluminum gallium garnets were synthesized by high temperature solid-state reaction in a carbon reducing atmosphere. The ytterbium aluminum garnets were characterized by X-ray powder diffraction, UV-Vis diffuse reflectance spectra, photoluminescence spectra and decay curves. Moreover, the substitution effect for the Al^3+ sites with Ga^3+ in 0.5 at%Ce:Yb3 Al(5-x)GaxO(12)(x = 0,1, 2, 3, 4, 5) garnets were discussed. With the increase of Ga^3+ ion concentration, the visible absorption peaks within 400-450 nm have blue shift phenomenon,while the absorption peaks in the range of 330-350 nm and the absorption band edge red shifts.Furthermore, the short decay times are very short with less than 10 ns due to the Yb^3+ + Ce^3+→ Yb^2+ + Ce^4+ electron transfer reaction.
基金supported by the German Scientific Council as part of a program on Magnetic Resonance
文摘In this review article, we present recent developments and improvements in magnetic resonance sounding (MRS), a newly established geophysical exploration method that provides unique information about hydrogeophysical properties due to its direct sensitivity to hydrogen protons and proton dynamics. Starting with the most sophisticated and complete MRS formulation, we give a detailed view on how to solve the equation, i.e., inverting exactly for all model parameters: water content, decay time, and resistivity. Giving a short review of general inversion schemes used in geophysics, the special properties of MRS inversion are evaluated and the development of MRS inversion over recent years is shown. We present the extension of MRS to magnetic resonance tomography (MRT), i.e., the extension to two-dimensional investigations and appropriate inversions. Finally, we address restrictions, limitations, and inconsistencies as well as future developments.
基金Project (No.81070885) supported by the National Natural Science Foundation of China
文摘The photoplethysmogram(PPG) of a pulse wave,similar in appearance to the arterial blood pressure(ABP) waveform,contains rich information about the cardiovascular system.The decay time constant RC,equal to the product of peripheral resistance R and total arterial compliance C,is a meaningful cardiovascular model parameter in vascular assessment.Using or ameliorating the existing ABP methods does not achieve a satisfactory estimation of RC from the PPG volume pulse(VRC).Thus,a novel non-iterative shape method(NSM) of evaluating VRC is introduced in this paper.The mathematic expression between a novel,readily available morphological parameter called the area difference ratio(ADR) and VRC was established.As it was difficult to calculate VRC from the complicated expression analytically,we recommend estimating it using a piecewise linear interpolation criterion.Also,since the effect of the PPG magnitude is eliminated in the calculation of ADR,precaliberation or normalization is dispensable in the NSM.Results of human experiments indicated that the NSM was computationally efficient,and the simulation experiments confirmed that the NSM was theoretically available for ABP.
基金Supported by NSFC(11271290)GSPT of Zhejiang Province(2014R424062)
文摘In this paper, we first show the global existence, uniqueness and regularity of weak solutions for the hyperbolic magnetohydrodynamics(MHD) equations in R^3. Then we establish that the solutions with initial data belonging to H^m(R^3) ∩ L^1(R^3) have the following time decay rate:║▽~mu(x, t) ║~2+║ ▽~mb(x, t)║~ 2+ ║▽^(m+1)u(x, t)║~ 2+ ║▽^(m+1)b(x, t) ║~2≤ c(1 + t)^(-3/2-m)for large t, where m = 0, 1.
文摘In this paper, we show the existence and regularity of mild solutions depending on the small initial data in Besov spaces to the fractional porous medium equation. When 1 < <em>α</em> ≤ 2, we prove global well-posedness for initial data <img src="Edit_b7b43d4c-00d8-49d6-9066-97151fb5c337.bmp" alt="" /> with 1 ≤ <em>p</em> < ∞, 1 ≤ <em>q</em> ≤ ∞, and analyticity of solutions with 1 < <em>p</em> < ∞, 1 ≤ <em>q</em> ≤ ∞. In particular, we also proved that when <em>α</em> = 1, both <em>u</em> and <img src="Edit_a5af0853-8adc-4a08-b8a2-b9a70ea0f409.bmp" alt="" /> belong to <img src="Edit_03a932cc-aa58-4568-83ad-f16416cc7b71.bmp" alt="" />. We solve this equation through the contraction mapping method based on Littlewood-Paley theory and Fourier multiplier. Furthermore, we can get time decay estimates of global solutions in Besov spaces, which is <img src="Edit_083986e9-4e1c-4494-ac5d-a7d30a12df97.bmp" alt="" /> as <em>t</em> → ∞.
文摘This study investigates the effect of the magnetic field on the transient density of excess minority charge carriers in the base of a series-connected vertical junction silicon solar cell. The solar cell is presented in open circuit transient operation. The magnetic field through the Laplace force which deflects the photogenerated carriers from their initial trajectory towards the lateral surfaces reducing their mobility, diffusion and conduction, will certainly influence the decay time of the transient regime. The transient density of excess minority carriers in the base is a sum of infinite terms whose decay time of the different harmonics is studied.
基金partially supported by the National Natural Science Foundation of China(11926354,11971496)Natural Science Foundation of Guangdong Province(2019A1515011320,2021A1515010292,2214050001249)+2 种基金Innovative team project of ordinary universities of Guangdong Province(2020KCXTD024)Characteristic innovation projects of ordinary colleges and universities in Guangdong Province(2020KTSCX134)the Education Research Platform Project of Guangdong Province(2018179)。
文摘In this paper,we study the global existence and decay rates of strong solutions to the three dimensional compressible Phan-Thein-Tanner model.By a refined energy method,we prove the global existence under the assumption that the H^(3) norm of the initial data is small,but that the higher order derivatives can be large.If the initial data belong to homogeneous Sobolev spaces or homogeneous Besov spaces,we obtain the time decay rates of the solution and its higher order spatial derivatives.Moreover,we also obtain the usual L^(p)-L^(2)(1≤p≤2)type of the decay rate without requiring that the Lpnorm of initial data is small.
基金Supported by National Natural Science Foundation of China(11271305)
文摘In this paper, we study the non-isentropic compressible magnetohydrodynamic system with a time periodic external force in R^n. Under the condition that the optimal time decay rates are obtained by spectral analysis, we show that the existence, uniqueness and time-asymptotic stability of time periodic solutions when the space dimension n 〉 5. Our proof is based on a combination of the energy method and the contraction mapping theorem.
文摘We consider the global existence and decay of integral solutions to the parabolic-parabolic Keller-Segel system in d-dimension.On the one hand,by Banach fixed point theorem and some properties of heat kernel,we prove the local existence and the global existence of integral solutions for the different initial data under some conditions that involve the size of the initial data.On the other hand,in the case of global solutions,we obtain their optimal time decay by Gronwall’s lemma.
文摘In this paper,it is proved that the weak solution to the Cauchy problem for the scalar viscous conservation law,with nonlinear viscosity,different far field states and periodic perturbations,not only exists globally in time,but also converges towards the viscous shock wave of the corresponding Riemann problem as time goes to infinity.Furthermore,the decay rate is shown.The proof is given by a technical energy method.
文摘Oxygen/glucose deprivation (OGD) has been widely used as an in vitro model of focal ischemia, where the blood flow is severely reduced and neurons rapidly die. However, adjacent to the focal region is ‘penumbra', where residual blood flow remains oxygen and glucose supplies are at low levels. To model this pathological genesis, we developed a partial OGD (pOGD) protocol in a rat brain slice. This model met two requirements: oxygen was partially deprived and glucose was reduced in the perfusion buffer. Therefore we investigated the effect of pOGD on gama-aminobutyric acid (GABAA) receptor-mediated inhibitory postsynaptic currents (IPSCs) in CA1 neurons of a hippocampal slice through whole-cell patch-clamp technique. We found that the amplitude and decay time of IPSCs were increased immediately during pOGD treatment. And the enhancement of IPSCs amplitude resulted from an increase of the synaptic conductance without a significant change in the reversal potential of chloride. These results suggested that the nervous system could increase inhibitory neurotransmission to offset excitation by homeostasis mechanisms during the partial oxygen and glucose attack.
文摘Upconversion (UC) phosphor Tm3+ doped YF3 nano-erystals were prepared by hydrothermal method under different conditions and characterized by Field Transmission electron microscopy (TEM), Scanning electron microscopy (SEM) and X-ray diffraction (XRD). Their UC luminescence properties were studied by fluorescence spectrophotometer with 980 nm diode laser excitation, and impact of different grain sizes and morphology on the UC luminescence intensity was discussed. The fluorescence decay lifetime was calculated by Multi-exponential function fitting method. Results show that UC emission intensity was enhanced with the reduction of grain size, and the decay lifetime is 0.60 us.
文摘The optical properties of LaCl3:Ce crystal are reported in this paper. Optical transmission spectrum, photoluminescence and time resolved photoluminescence spectra at different temperatures are investigated. It is found that optical transmittance is as high as 80% between 320 nm and 600 nm, and no obvious absorption band is found in this region. Emission intensity and decay time of photoluminescence are quite stable with the change of the temperature between 80 K and 500 K. No thermal quenching is present up to 500 K, and decay time keeps at 17±2 ns. With the increase of the temperature, the whole emission bands and excitation bands present broadening and overlapping, leading to the strengthening of re-absorption of the Ce^3+ emission, which makes the emission spectra have a red shift trend.
基金supported by the National Basic Research Program of China (Grant No. 6139702)the National Natural Science Foundation of China (Grant Nos. 60877029,60977035 and 60907021)+1 种基金the Natural Science Foundation of the Tianjin Education Committee,China (Grant No. 20071207)the Natural Science Foundation of Tianjin,China (Grant Nos. 09JCYBJC01400and 07JCYBJC06400)
文摘A series of aAl5O12:Ce (YAG:Ce) phosphors doped with different Si4+ concentrations is prepared by solid-state reaction. The temperature dependent characteristics of luminescent spectrum and decay time of Ce3+ are investigated. With Si4+ doped, the emission spectrum shows a blue shift clue to a decrease of the splitting of 5d levels of Ce3+ ion. The thermal stability is greatly improved by adding Si4+ because the activation energy AE increases from 0.1836 eV to 0.2401 eV. The study of the decay times against temperature for various doping concentrations of Si4+ shows that the calculated nonradiative decay rate is affected by Si4+ substitution. The results are explained by the configurational coordinate diagram.
基金supported by the NSFC (10871134),supported by the NSFC (10871134, 10771008)the NCET support of the Ministry of Education of China+1 种基金the Huo Ying Dong Fund (111033)the funding Project for Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality (PHR201006107)
文摘This is a survey paper on the study of compressible Navier-Stokes-Poisson equations. The emphasis is on the long time behavior of global solutions to multi-dimensional compressible Navier-Stokes-Poisson equations, and the optimal decay rates for both unipolar and bipolar compressible Navier-Stokes-Poisson equations are discussed.
基金supported by the NSFC (10871134)supported by the NSFC (10871134,10910401059)+1 种基金the funding Project for Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality (PHR201006107)supported by the General Research Fund of Hong Kong,City Univ.103108
文摘The compressible non-isentropic bipolar Navier-Stokes-Poisson (BNSP) sys- tem is investigated in R3 in the present paper, and the optimal time decay rates of global strong solution are shown. For initial data being a perturbation of equilibrium state in Hl(R3) (R3) for 1 〉 4 and s E (0, 1], it is shown that the density and temperature for each charged particle (like electron or ion) decay at the same optimal rate (1 + t)-3/4, but the momentum for each particle decays at the optimal rate (1 + t)-1/4-3/2 which is slower than the rate (1 + t)-3/4-3/2 for the compressible Navier-Stokes (NS) equations [19] for same initial data. However, the total momentum tends to the constant state at the rate (1 +t)-3/4 as well, due to the interplay interaction of charge particles which counteracts the influence of electric field.
基金supported partially by the NNSFC Grant(11371151)the Scientific Research Foundation of Graduate School of South China Normal University
文摘In this paper, we consider the Vlasov-Maxwell-Fokker-Planck system with relativistic transport in the whole space. The global solutions to this system near the relativistic Maxwellian are constructed and the optimal time decay rate of global solutions are also obtained by an approach by combining the compensating function and energy method.