Experimental Design Methods

The effect of different pai ameters such as temperature, pressure, modifier volume, dynamic and static extraction time on the SFE of the plant were investigated. The orthogonal array experimental design method was chosen to determine experimental plan, (5 ). In this design the effect of five parameters and each at five levels were investigated on the extraction efficiency and selectivity [4]. 

As a second example let us consider the fed-batch bioreactor used by Ka-logerakis and Luus (1984) to illustrate sequential experimental design methods for dynamic systems. The governing differential equations are (Lim et al., 1977) ... 

The Taguchi method consists of a philosophy of quality, experimental design methods to build in robustness and methods to analyze data obtained from the experiments. All these topics are treated in text books [10-13]. 

The philosophy is simple make products with build-in robustness against all kinds of environmental disturbances and fluctuations. The experimental design methods are presented as linear graphs and orthogonal arrays, but are not essentially different from established designs like Factorial and Fractional Factorial designs [12]. The methods of analyzing... 

Many developments have been made in the use of statistics to aid in experimental design over the last decades. The most important aspect of experimental design methods is that they provide a mathematical framework for changing all pertinent factors simultaneously, and achieve this in a small number of experiments. The description of such methods, though, is beyond the scope of this book and the reader is referred to the literature (Box et al., 1978 Bayne and Rubin, 1986 Haaland, 1989 Morgan, 1991) or to the internet for the latest design software (e. g. StatSoft, 1999). 

The library design software, Library Studio , is part of a suite of software applications, Renaissance , developed at Symyx to design experiments, control robotics, integrate and control analytical devices, and capture and search experimental designs, methods, and data. 

Statistical methods can often be used to understand what variables are important for the preparation of catalysts, for the optimization of selectivity and conversion and other phenomena. Screening and experimental design methods have been used by Ebert et al. to optimize the selectivity of isomerization of 1,5-cyclooctadiene to 1,4-cyclooctadiene.38 Silica supported Ir4(CO)i2 was used as a catalyst and experimental data from the experimental design were used to optimize the yield of 1,4-cyclooctadiene with selectivity of 50 %. 

For a given rate expression this yields the optimal parameter values, but it has to be decided whether the rate expression is the most adequate one. This selection can be based on statistical analysis and on physical significance of the parameter values (for example they should be positive in many cases). Additional experimental effort can be used towards further model discrimination by carefully planning experiments - a kind of experimental design method. 

Experimental Design Methods 373 Table 5.13 The matrix for a 2 experimental plan (example of gas permeation). 

Experimental Design Methods 377 Table 5.17 Calculation of the interaction coefficients for model (5.110). 

Selbrede238, published a characterization of the SiH2Cl2-WSix process in a batch reactor using an experimental design method. In comparing his results with those of Wu and Price we should keep in mind that the temperature in Selbrede s work are hot plate temperatures and that the actual wafer temperature can easily be 100°C lower in the pressure regime studied (see also chapter VII). The studied process window was ... 

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