Browsing by Author "Tort-Martorell, Xavier"
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Item Identifying dispersion effects in robust design experiments - Issues and improvements(2007-08) Pozueta, Lourdes; Tort-Martorell, Xavier; Marco, Lluis; Centros PRE-FUSION TECNALIA - (FORMER)The two experimental methods most commonly used for reducing the effect of noise factors on a response of interest Y aim either to estimate a model of the variability (V(Y), or an associated function), that is transmitted by the noise factors, or to estimate a model of the ratio between the response (Y) and all the control and noise factors involved therein. Both methods aim to determine which control factor conditions minimise the noise factors' effect on the response of interest, and a series of analytical guidelines are established to reach this end. Product array designs allow robustness problems to be solved in both ways, but require a large number of experiments. Thus, practitioners tend to choose more economical designs that only allow them to model the surface response for Y. The general assumption is that both methods would lead to similar conclusions. In this article we present a case that utilises a design based on a product design and for which the conclusions yielded by the two analytical methods are quite different. This example casts doubt on the guidelines that experimental practice follows when using either of the two methods. Based on this example, we show the causes behind these discrepancies and we propose a number of guidelines to help researchers in the design and interpretation of robustness problems when using either of the two methods.Item Optimization of a car brake prototype as a consequence of successful DOE training(2004-08) Marco, Lluís; Tort-Martorell, Xavier; Cuadrado, Juan A.; Pozueta, Lourdes; Centros PRE-FUSION TECNALIA - (FORMER)In this article we discuss the importance of running a successful experiment while teaching design of experiments (DOE) to working engineers. A key aspect is to build engineer's confidence in DOE methodology and in their capabilities of using it, and this means keeping the content simple and developing a learning-by-doing experience. We cover several aspects of the course content and preparation, but the emphasis is in the preparation, follow up, roles of teachers and attendants, and the planning and steps followed in preparing and conducting the real experiment. A crucial aspect is making sure that the attendants recognize that they have gained valuable knowledge. A measure of the success of the approach suggested is that after the course and the real experiment associated with it were finished, Bosch's engineers have run several other experiments completely on their own. Even though a professional statistician may have done a better job, the use of the techniques were correct and the learning from the experiments was highly valuable.