SECS— simulation and

Plan Representation in SECS. The SECS Simulation and Evaluation of Chemical Synthesis program explicitly represents its plans(2) as a list structure of goal instructions with logical connectives. A goal instruction can specify one of the following ... 

Wipke, W. T. Braun, H. Smith, G. Choplin, F. Sieber, W. "SECS — Simulation and Evaluation of Chemical Synthesis Strategy and Planning American Chemical Society Vol. 61,... 

Wipke, W. T., Brown, H., Smith, G., Choplin, F., Seber, W. SECS-Simulation and evaluation of chemical synthesis strategy and planning , ACS 61, 1977... 

Corey EJ, Wipke WT, Cramer RD, Howe WJ (1972) Computer-assisted synthetic analysis. Facile man-machine communication of chemical structure by interactive computer graphics, J Am Chem Soc 94/2 421 Wipke WT, Braun H, Smith G, Choplin F, SieberW (1977) SECS — Simulation and evaluation of chemical synthesis Strategy and planning, in Computer-assisted organic synthesis, Wipke WT, Howe WJ ed, ACS Symposium Series, p 98... 

SECS—Simulation and Evaluation of Chemical Synthesis Strategy and Planning... 

W. T. Wipke, H. Braun, G. Smith, F. Choplin, and W. Sieber. in SECS - Simulation and Evaluation of Chemical Synthesis in Computer Assisted Organic Synthesis, eds. W. T, Wipke... 

The evolution of molecular graphics (7) is described in an earlier ACS Symposium Series book (77) which acts as an interesting precursor to this present volume. Chemical reaction systems such as LHASA (Logic and Heuristics Applied to Synthetic Analysis) 18) and SECS (Simulation and Evaluation of Chemical Synthesis) (79) had long used graphics but it was some time before the first in-house, proprietary system appeared, attracting much interest in the chemical and pharmaceutical industries. This was Upjohn s Compound Information System, COUSIN 20-21). 

In the next section we describe the basic models that have been used in simulations so far and summarize the Monte Carlo and molecular dynamics techniques that are used. Some principal results from the scaling analysis of EP are given in Sec. 3, and in Sec. 4 we focus on simulational results concerning various aspects of static properties the MWD of EP, the conformational properties of the chain molecules, and their behavior in constrained geometries. The fifth section concentrates on the specific properties of relaxation towards equilibrium in GM and LP as well as on the first numerical simulations of transport properties in such systems. The final section then concludes with summary and outlook on open problems. 

The first step in studying phenomenological theories (Ginzburg-Landau theories and membrane theories) has usually been to minimize the free energy functional of the model. Fluctuations are then included at a later stage, e.g., using Monte Carlo simulations. The latter will be discussed in Sec. V and Chapter 14. 

Figure 4.4 Plot of enzyme complex concentration as a function of time for the Michaelis-Menten mechanism of Equations (4.22). The concentration of ES predicted from a kinetic simulation of Equations (4.22) is plotted as a solid line. The parameter values used are k+ = 1000M-1 sec-1,k i = 1.0sec-1,k+2 = 0.1 sec-1, and E0 = 0.1 mM. The left plot illustrates the fast-time kinetics. The fast-time variable n(r) predicted by Equation (4.29) is plotted as a dashed line.

In the current paper, we discuss some of the new approaches and results that have been developed and obtained recently within the context of such molecular modeling research, and in particular with the mean field and Monte Carlo studies of a lattice model. The next section describes the Gaussian random field method (Woo et al, 2001), which provides a computationally efficient route to generate realistic representations of the disordered mesoporous glasses. Application of the mean field theory, and Monte Carlo simulations are described in Secs. 3 and 4, respectively. 

As mentioned in Sec. 3.1.1, the chemical reactions driving the detonation depicted in Fig. 4, obtained with Model I, are largely complete between 2 nm and 5 nm behind the detonation front. When coupled with continuum theory, this extremely short reaction zone length implies that the model should exhibit a critical width for detonation that is small enough to be directly accessible in a molecular dynamics simulation of a two-dimensional strip. The results of this section show that this is the case. The results further establish the connection between our simulations and continuum theory and suggest the possibility of observing nanoscaJe detonations in highly reactive ribbons. 

The outline of the paper is as follows. In Sec. 1, the expression used to fit the VESUVIO data is derived. Sec. 2 describes the way in which the instrument resolution is incorporated into the data analysis. Sec. 3 describes the Monte Carlo (MC) procedure, used to test the fitting programs. In Secs. 4 to 6 the influence of instrumental effects on the results are evaluated, using MC simulations and also by comparing data taken under different experimental conditions. Sec. 4 considers the effects of the correction for the incident beam intensity. Sec. 5 considers the systematic errors generated by approximations made to incorporate the instrument resolution in the fitting programs. Sec. 6 discusses effects dependent on sample size, such as attenuation, multiple scat-... 

The conversion could be enhanced for the forward reaction if the reverse reaction involving ethene and 2-butene is minimized. Further, since 2-butene desorption is a controlling factor due to its strong sorptive properties, 2-butene removal, in particular, will allow improved rate of reaction and product separation with the use of a sorbent such as y-Al203. The effect of the PSR operation (cycle time = 40 sec) on the reactor performance was tested through simulations and by conducting experiments. Step inputs in inlet feed composition containing propene with helium carrier were conducted with clean sorbent beds and constant total gas flow rates. The results, compared with theoretical predictions, are shown in Fig. 9. Because ethene has... 

Fig. 9 Simulations and experimental results gas phase exit composition for propene metathesis in fixed-bed catalytic reactor with PSR (cycle time = 240 sec, Co = 1.2 x 10 " mol/cm, Chc = 8 x 10 mol/cm ). (From Ref. " with permission.)...

Simulation and Evaluation of Chemical Synthesis (SECS) was developed by Wipke and uses heuristic methods similar to LHASA but puts special emphasis on stereochemistry, topology, and energy minimization [112]. 

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