Strength Optimization Programs

The method of optimization is a brute-force search technique. All the possible laminates that can be obtained by changing the individual laminae orientations by 5° increments are candidates for the optimization process. We consider RC7 because this program is widely used and because it is representative of the brute-force search technique. The basic question is because we must carry a certain load, what laminate do we need We have no idea how many layers are required, much less their orientation, but we must start someplace. 

release the constraint of having the first layer still oriented at a. That constraint must surely seem quite arbitrary and not at all physically reasonable. Also, we must admit that the second layer probably is not in its proper orientation either. Thus, we will allow the two laminae orientations to float from [01/02 to something else. And we will call that procedure for changing the laminae lamina reorientation. There are two stages of lamina reorientation (1) coarse reorientation and (2) fine reorientation. 

This brute-force search strategy is followed as more layers are added because we do not know how many layers we need for the prescribed load. If the load is very high, perhaps we will need 19 layers, and we will work our way up to that laminate by adding one layer at a time and finding the best laminate of that number of laminae. 

BEST SECOND-LAMINA ORIENTATION IF FIRST LAMINA FIXED 

Introduction to Design of Composite Structuies 439 Table 7-5 Number of Calculations in RC7 

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Overall, it seems that PHREEQC, except for the problems with high ionic strengths that require the application of PITZER equations, is the optimal program for the solution of both simple and more complex exercises and for onedimensional transport modehng with regard to user-friendliness, numerical stability, compactness and clarity of the data format as well as flexibility. It will be used for the solution of the exercises in chapter 3. The utilization of PHREEQC is presented in detail in chapter 2.2. 

This step encompasses procedures that are usually performed within the scope of an optimization. In doing so, mostly the interactions between the sample and the stationary phase are changed. The intention is a change of the retention factor k (mostly enhancement), but ideally also of the separation factor Ct. Otherwise, at constant interaction strength ( chemistry constant and therefore k and a as well), one attempts to enhance the plate number or in the case of a miniaturization to prevent dilution or to enhance the relative mass sensitivity. Using a trial-and-error procedure, one needs 1-2 weeks. Using a systematic procedure, aided perhaps by an optimization program, the time can be reduced measurably see Part 4 for chapters on computer-aided optimization. 

Raevsky, O., Hydrogen bond strength estimation by means of the HYBOT program package, in Computer-assisted lead finding and optimization, H. van de Waterbeemd, B. Testa and G. Folkers, eds, Verlag Helvetica Chimica Acta, Basel, 1997, 367-378. 

The concept of linear solvent strength (LSS) gradients developed by Snyder (see also sections 5.4.2 and 6.2.2) incorporates optimization of both the shape and the slope of gradient programs. The shape of an LSS gradient is determined by... 

Raevsky, O.A. (1997). Hydrogen Bond Strength Estimation by Means of the HYBOT Program Package. In Computer-Assisted Lead Finding and Optimization, (van de Waterbeemd, H., Testa, B. and Folkers, G., eds.), Wiley-VCH, Weinheim (Germany), pp. 367-378. 

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