Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Consistent initial value

As a first step to solve the initial value problems of (1.1) we have to determine consistent initial values 2/( 0) = Vo- For this we compute a steady state solution to (1.1), i.e. a solution of the system of nonlinear equations F y) = 0 which comes from the discretization of (1.1) at t = to, with if to) = 0. In general, firstly we must look for a rough initial point yinit starting from to compute an updated approximation yoo such that yoo is within the region of convergence of an iteration method solving F y) = 0. Secondly we update yoo to a consistent initial value yo for the initial value problem. In the following our concern is on the latter point while the former is under development. [Pg.72]

Remark 2.7.4 The second part (ii) of the proof makes no use of the particular structure of and and can therefore be applied to any nonsingular matrix pencil. From the last part of the proof it can be seen that the eigenvectors corresponding to the additional zero eigenvalues are not consistent with the DAE. Thus, these eigenvalues cannot be excited by consistent initial values. [Pg.76]

As discussed in Sec. 5.1.2 a solution exists only for consistent initial values. However, if the initial values at the shooting nodes are degrees of freedom for... [Pg.259]

Additionally, the infeasible path method avoids the elimination of the algebraic variables A in favor of y,0. The information available from measurements for both types of variables can be brought in. Although fcis Sj O) 0 during the solution process the solution of the DAE remains a well-posed problem because the consistent extension of the IVP always leads to consistent initial values for the DAE (7.3.1). [Pg.260]

Step 2 an initial configuration representing the partially filled discretized domain is considered and an array consisting of the appropriate values of F - 1, 0.5 and 0 for nodes containing fluid, free surface boundary and air, respectively, is prepared. The sets of initial values for the nodal velocity, pressure and temperature fields in the solution domain are assumed and stored as input arrays. An array containing the boundary conditions along the external boundaries of the solution domain is prepared and stored. [Pg.145]

X is an acidity function based on the first-order approximation, Eq. (8-92). Values of X have been assigned by an iterative procedure. The data consist of values of Cb/cbh+ as functions of Ch+ for a large number of indicators. For each indicator an initial estimate of pXbh+ and m is made and X is calculated with Eq. (8-94). This yields a large body of X values, which are fitted to a polynomial in acid concentration. From this fitted curve smoothed X values are obtained, and Eq. (8-94), a linear function in X. allows refined values of pXbh + and m to be obtained. This procedure continues until the parameters undergo no further change. Table 8-20 gives X values for sulfuric and perchloric acid solutions. ... [Pg.451]

They also showed that if Olivier s data183 for this system was treated as three-halves-order instead of second-order as he had assumed, then the initial rate coefficients in his kinetic runs were satisfactorily consistent, contrary to his observation (Table 50). It was necessary to use the initial values since Olivier found a decrease in the rate coefficients with time, contrary to the observations of Jensen and Brown, who assumed, therefore, that Olivier s reagent may have contained impurities. [Pg.81]

A study over a broader range of disulfonate monosulfonate ratios was then conducted with a series of AOS 2024 surfactants. Results are shown in Fig. 5. The carbon number and hydrophobe branching were held constant. The AS HAS ratio was 75 25. At a disulfonate monosulfonate ratio (D M) of 7 93, addition of less than 200 ppm calcium ion decreased solution transmittance to less than 10% of its initial value. When the disulfonate content of AOS 2024 was increased to 38 wt % (di monosulfonate ratio of 38 62), slightly more than 1000 ppm calcium ion was required to reduce solution transmittance to less than 10% of its initial value. When the surfactant consisted predominantly of disulfonate (di monosulfonate ratio of 84 16), the addition of more than 41,000 ppm calcium ion reduced the transmittance by less than 5% from its initial value. [Pg.380]

The extension to multiple reactions is done by writing Equation (3.1) (or the more complicated versions of Equation (3.1) that will soon be developed) for each of the N components. The component reaction rates are found from Equation (2.7) in exactly the same ways as in a batch reactor. The result is an initial value problem consisting of N simultaneous, first-order ODEs that can be solved using your favorite ODE solver. The same kind of problem was solved in Chapter 2, but the independent variable is now z rather than t. [Pg.82]

As given above, the statements that adjust the exponents m and n have been commented out and the initial values for these exponents are zero. This means that the program will fit the data to. = k. This is the form for a zero-order reaction, but the real purpose of running this case is to calculate the standard deviation of the experimental rate data. The object of the fitting procedure is to add functionality to the rate expression to reduce the standard deviation in a manner that is consistent with physical insight. Results for the zero-order fit are shown as Case 1 in the following data ... [Pg.214]

The Leibniz rule (see Integral Calculus ) can be used to show the equivalence of the initial-value problem consisting of the second-order differential equation d2y/cbd + A(x)(dy/dx) + B(x)y = fix) together with the prescribed initial conditions y(a) = y . y (a) = if, to the integral equation. [Pg.36]

The observations were performed at ESO using the 1.52m telescope and FEROS. The obtained spectra have high nominal resolving power (R 48000), and S/N 500 at maximum and a coverage from 4000 A to 9200 A. Many spectra were acquired for all sample stars. The atmospheric parameters (Teff, log g, [Fe/H] and microturbulence velocities) have been obtained through an iterative and totally self-consistent procedure from Fe lines of the observed spectrum. The initial values of Teg were obtained from a (B-V) vs Teg calibration and log were determined from Hipparcos parallaxes and evolutionary tracks. The [O/Fe] abundances were derived by fitting synthetic spectra to the observed one. [Pg.50]

Set I is the data for a first-order reaction we can analyze those items of data to determine the half-life. In the first 75 s, the concentration decreases by a bit more than half. This implies a half-life slightly less than 75 s, perhaps 70 s. This is consistent with the other time periods noted in the answer to Review Question 18 (b) and also to the fact that in the 150 s from 50 s to 200 s, the concentration decreases from 0.61 M to 0.14 M, a bit more than a factor-of-four decrease. The factor-of-four decrease, to one-fourth of the initial value, is what we would expect of two successive half-lives. We can determine the half-life... [Pg.322]

We could detect no changes in [Ca2+]L during spontaneous transients, consistent with the conclusions drawn above. Indeed, we found that if SR Ca2+ was elevated, then spontaneous activity was suppressed until SR Ca2+ levels returned to their initial value. This is also consistent with SR activity inhibiting rather than potentiating [Ca2+]j and force. [Pg.15]

INITIAL VALUES OF CRUSHING STRENGTH (So) AND DISINTEGRATION TIME (Do) OF TABLETS CONSISTING OF A FILLER-BINDER AND A DISINTEGRANT... [Pg.332]


See other pages where Consistent initial value is mentioned: [Pg.37]    [Pg.77]    [Pg.140]    [Pg.140]    [Pg.153]    [Pg.37]    [Pg.77]    [Pg.140]    [Pg.140]    [Pg.153]    [Pg.276]    [Pg.2348]    [Pg.194]    [Pg.157]    [Pg.293]    [Pg.827]    [Pg.106]    [Pg.165]    [Pg.574]    [Pg.319]    [Pg.328]    [Pg.973]    [Pg.377]    [Pg.379]    [Pg.393]    [Pg.9]    [Pg.177]    [Pg.187]    [Pg.413]    [Pg.43]    [Pg.270]    [Pg.234]    [Pg.259]    [Pg.314]    [Pg.133]    [Pg.186]    [Pg.632]    [Pg.314]    [Pg.323]   
See also in sourсe #XX -- [ Pg.140 ]




SEARCH



Consistent extended initial value problems

Initial values

© 2024 chempedia.info