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Number system Taylor series

The potential energy V of the elastomer is presumed to be given as a function of the atomic coordinates x (lwell-defined equilibrium shape, there must be equilibrium positions x for all atoms that are part of the continuous network. Expand the potential in a Taylor series about the equilibrium positions, and set the potential to zero at equilibrium, to obtain... [Pg.244]

When a molecule A is attacked by another molecule B, it will be perturbed in either its number of electrons NA or its external potential vA(r). At the very early stages of the reaction, the total electronic energy of A, EA can be expressed as a Taylor series expansion around the isolated system values NA and v jfr)... [Pg.539]

It is difficult to solve the system of Eqs. (39)—(41) for these boundary conditions. However, certain simplifying assumptions can be made, if the Prandtl number approaches large values. In this case, the thermal boundary layer becomes very thin and, therefore, only the fluid layer near the plate contributes significantly to the heat transfer resistance. The velocity components in Eq. (41) can then be approximated by the first term of their Taylor series expansions in terms of y. In addition, because the nonlinear inertial terms are negligible near the wall, one can further assume that the combined forced and free convection velocity is approximately equal to the sum of the velocities that would exist when these effects act independently. Therefore, for assisting flows at large Prandtl numbers (theoretically for Pr -> oo), Eq. (41) can be rewritten in the form ... [Pg.26]

To describe the chemical reactivity in the context of DFT, there are several global and local quantities useful to understand the charge transfer in a chemical reaction, the attack sites in a molecule, the chemical stability of a system, etc. In particular, there are processes where the spin number changes with a fixed number of electrons such processes demand the SP-DFT version [27,32]. In this approach, some natural variables are the number of electrons, N, and the spin number, Ns. The total energy changes, estimated by a Taylor series to the first order, are... [Pg.4]

Consider an atom in a cell, Cq. The interactions with atoms in nearby cells are calculated using the usual pairwise formulae. There are 27 such cells (i e. the cell in which the atom is positioned and the surrounding 26 cells). The interaction between the atom and all of the atoms in each of the faraway cells is then calculated using the multipole expansion. The potential due to a faraway cell will be approximately constant for all atoms in the cell of current interest, Cq (the cells are usually small, containing on average four atoms). Thus the potential due to each faraway cell can be represented as a Taylor series expansion about the centre of Cq. If there are M cells in total then there are M — 27 faraway cells then the calculation of these cell-cell interactions for the entire system will be of order M(M —27). As the number of cells is approximately equal to the number of atoms, this still leaves us with a quadratic dependency upon the number of atoms present (though it does now vary as about N /16, if there is an average of four atoms per cell). [Pg.342]

The projection-based model order reduction algorithm begins with a spatial discretization of the governing PDEs to attain the dynamic system equations as Eq. 11. Specifically, here, X(t) is the state vector of unknowns (a function of time) on the discrete nodes, n is the total number of nodes A is formulated by the numerical discretization Z defines the functions of boundary conditions and source terms and B relates the input function to each state X. Equation 11 can be recast into the frequency domain in terms of transfer function T(s). T(s) then is expanded as a Taylor series at s = 0 yielding... [Pg.2274]

We see that each additional teim in the Taylor series requires storage of another set of N delayed variables. Our experience suggests that a fourth-order expansion generally gives satisfactory results and that increasing the number of steps per interval N is more efficacious with stiff DDE systems than is increasing the order of the Taylor series approximation. [Pg.215]

Another considerable simplification is achieved by the assumption, that numbers of moles (molar fractions), being variables of the functions (6.58), (6.59) are mutually separable. Since in most methods non-linear relations are converted to sets of linear equations by means of Taylor series development, this assumption means that the first or higher partial derivatives do not contain terms which would mutually functionally bind individual components. The advantage then consists in the fact, that procedures derived for ideal gas systems can be employed with only slight modifications, without limiting the degree of complexity of the equation of state employed. [Pg.180]

PLS and other projection methods have a theoretical foundation based on perturbation theory of a multivariable system, This derivation shows that projection models can approximate any data table as long as there is a certain degree of similarity between the objects (observations, matrix rows) and the greater the similarity between the objects and the greater the number of model components, the better the approximation, This is very similar to the derivation of polynomials as Taylor series that can approximate any continuous function in a limited interval. [Pg.2010]

Ho is die Hamiltonian for the unperturbed system and p is the dipole moment operator. From the perturbed wave functions evaluated at SCF or Cl level the dipole moment value p(f) is obtained. From the Taylor series expansion [ q. (10.1)] the coefficients a, p and y can be derived from calculations at a number of distortions along particular coordinate and field direcdons. Molecular polarizability is then obtained from the expression... [Pg.274]

It was soon realised that at least unequal intervals, crowded closely around the UMDE edge, might help with accuracy, and Heinze was the first to use these in 1986 [300], as well as Bard and coworkers [71] in the same year. Taylor followed in 1990 [545]. Real Crank-Nicolson was used in 1996 [138], in a brute force manner, meaning that the linear system was simply solved by LU decomposition, ignoring the sparse nature of the system. More on this below. The ultimate unequal intervals technique is adaptive FEM, and this too has been tried, beginning with Nann [407] and Nann and Heinze [408,409], and followed more recently by a series of papers by Harriman et al. [287,288,289, 290,291,292,293], some of which studies concern microband electrodes and recessed UMDEs. One might think that FEM would make possible the use of very few sample points in the simulation space however, as an example, Harriman et al. [292] used up to about 2000 nodes in their work. This is similar to the number of points one needs to use with conformal mapping and multi-point approximations in finite difference methods, for similar accuracy. [Pg.211]

Tanks-in-series model. This model is based on the assumption that the system is composed of n perfect minimixing chambers resembling chromatographic plates, and its accuracy increases with increase In the number of plates considered. In any case, it describes more factually ordinary FIA systems than doss Taylor s model. [Pg.164]


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See also in sourсe #XX -- [ Pg.57 ]




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