Browsing by Author "Chang, WY"

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Green's function and eigenvalue representations of time lag for membrane permeation transport
(2002-10-01)
Chen, JS
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Chang, WY
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應用化學系
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Department of Applied Chemistry
Modeling membrane permeation transport by particles undergoing random walk over a one-dimensional lattice leads to a master equation, which describes the time dependence of particle concentration. With the stipulated conditions appropriate for absorptive permeation, the master equation is then solved in the Laplace domain to find the flux into the receiver, which in turn is used to formulate the time lag, t(L). It turns out t(L) can be represented by trace(A(-1)), where A is the transition matrix associated with the master equation. An analog to this representation for the continuous coordinate space is t(L) = (0)integral(h) G(x,x)dy, where G(x, x) is the Green's function associated with the steady-state diffusion equation with zero value at both boundaries 0 and h, and the source and observation points coinciding at x (0 < x < h). We have also provided a rigorous proof for this new Green's function representation of time lag. A bonus from the latter is that the time lag can be calculated t(L) = Sigma(n) 1/lambda(n) where lambda(n) is the eigenvalue of the transmission matrix. The directional symmetry of the time lag is easy to be interpreted on the basis of Green's function or eigenvalues representations.
Matrix-theoretical analysis in the Laplace domain for the time lags and mean first passage times for reaction-diffusion transport
(1997-05-15)
Chen, JS
;
Chang, WY
;
應用化學系
;
Department of Applied Chemistry
Siegel's matrix analysis of membrane transport in the Laplace domain [J. Phys. Chem. 95, 2556 (1991)], which is restricted to zero initial distribution, has been extended to including the case of nonzero initial distribution. This extension leads to a more general transport equation with Siegel's results as a special case. The new transport equation allows us to formulate the mean-first-passage time (t) over bar for various boundary conditions, if the initial distribution is stipulated to be of the Dirac delta-function type; and the steady-state permeability P and time lag t(L), if zero initial distribution is employed. Based on this matrix analysis we also propose an algorithm for quick and effective numerical computations of P, t(L), and ST Examples are given to demonstrate the application of this algorithm, and the numerical results are compared with the theoretical ones. The validity of the transport equation is also checked by a Green's function. (C) 1997 American Institute of Physics.
Matrix-theoretical analysis in the Laplace domain for the time lags and mean first passage times for reaction-diffusion transport
(1997-05-15)
Chen, JS
;
Chang, WY
;
交大名義發表
;
應用化學系
;
National Chiao Tung University
Siegel's matrix analysis of membrane transport in the Laplace domain [J. Phys. Chem. 95, 2556 (1991)], which is restricted to zero initial distribution, has been extended to including the case of nonzero initial distribution. This extension leads to a more general transport equation with Siegel's results as a special case. The new transport equation allows us to formulate the mean-first-passage time (t) over bar for various boundary conditions, if the initial distribution is stipulated to be of the Dirac delta-function type; and the steady-state permeability P and time lag t(L), if zero initial distribution is employed. Based on this matrix analysis we also propose an algorithm for quick and effective numerical computations of P, t(L), and ST Examples are given to demonstrate the application of this algorithm, and the numerical results are compared with the theoretical ones. The validity of the transport equation is also checked by a Green's function. (C) 1997 American Institute of Physics.
Pilot channel aided adaptable interference cancellation scheme for uplink DS/CDMA mobile radio systems
(2001)
Tang, CH
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Chang, WY
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Wei, CH
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
In this paper, we propose a pilot channel aided adaptable interference cancellation (IC) scheme which combines serial (SIC) and parallel (PIC) interference cancellation to adapt to different services under different circumstances for uplink wideband DS/CDMA system. The processing delay and computational complexity can be adjusted based on system loading and required performance. The interference between data channel signals and pilot channel signals under multipath fading channel are also taken into consideration. This results in better quality both on channel parameter estimation and user data detection. Compared with SIC and PIC, the proposed scheme shows better performance with reasonable hardware while it needs shorter processing delay than SIC.
Relation between fluxes for membrane reaction-diffusion transport studied by the matrix method
(1997-12-22)
Chen, JS
;
Chang, WY
;
應用化學系
;
Department of Applied Chemistry
The previous matrix-theoretical analysis of the time lags and mean first passage times for reaction-diffusion transport in the Laplace domain [J. Chem. Phys. 106, 8022 (1997)] has been extended to the problems of membrane permeation, absorption and desorption. A matrix transport equation has been derived to calculate the flux (in the Laplace domain) for specified initial and boundary conditions corresponding to membrane permeation, absorption or desorption. Seven equality relations between fluxes for reaction-free diffusion and one for diffusion accompanying reaction have been found. Among them are two new equality relations which have been discovered by this matrix analysis. (C) 1997 American Institute of Physics.
Relation between fluxes for membrane reaction-diffusion transport studied by the matrix method
(1997-12-22)
Chen, JS
;
Chang, WY
;
應用化學系
;
Department of Applied Chemistry
The previous matrix-theoretical analysis of the time lags and mean first passage times for reaction-diffusion transport in the Laplace domain [J. Chem. Phys. 106, 8022 (1997)] has been extended to the problems of membrane permeation, absorption and desorption. A matrix transport equation has been derived to calculate the flux (in the Laplace domain) for specified initial and boundary conditions corresponding to membrane permeation, absorption or desorption. Seven equality relations between fluxes for reaction-free diffusion and one for diffusion accompanying reaction have been found. Among them are two new equality relations which have been discovered by this matrix analysis. (C) 1997 American Institute of Physics.
Time moment analysis of first passage time, time lag and residence time problems via Taylor expansion of transmission matrix
(2000-03-08)
Chen, JS
;
Chang, WY
;
應用化學系
;
Department of Applied Chemistry
Taylor expansion (with respect to the Laplace variable, s) of the transmission matrix, T(s), has been developed for the diffusion transport with position-dependent diffusivity, D(x) and partition coefficient, K(x). First, we find the relation between the expansion coefficients of the matrix elements and the moments of the first passage times by connecting them to J(s), the Laplace transform of the escaping flux, J(t). The moments can be formulated by repeated integrals of K(x) and [D(x)K(x)](-1) from solving the backward diffusion equation subject to appropriate initial and boundary conditions. In this way, Taylor expansion coefficients of T-11(s), T-21(s), and T-22(s) are expressed in terms of the repeated integrals. Further application of the identity det[T(s)] = 1 leads to the Taylor expansion T-12(s). With the knowledge of the Taylor expansion of T(s), the formulation of the time moments for diffusion problems with position dependent D(x) and K(x) subject to various initial and boundary conditions is then just a simple, algebraic manipulation. Application of this new method is given to the membrane permeation transport and mean residence time problem. (C) 2000 American Institute of Physics. [S0021-9606(00)50810-1].