tailieunhanh - Modeling of Combustion Systems A Practical Approach 11

Tham khảo tài liệu 'modeling of combustion systems a practical approach 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 3__ Experimental Design and Analysis Chapter Overview How do fuel composition excess oxygen and furnace temperature fluctuations affect some important response such as process conversion rate or emissions What factors affect NOx and CO Are burners in similar process units behaving differently or alike What is the statistical uncertainty that the proposed model is correct To score models for these kinds of investigations we need some understanding of statistics. This chapter begins with some elementary statistics and distributions and progresses to its seminal tool for separating information from noise the analysis of variance. Next the chapter covers factorial designs the foundation of statistically cognizant experiments. We find that simple rules produce fractional factorials and reduce the number of required experiments. We show that by modifying the alias structure we can clear factors of certain biases. We then discuss the importance of replication in obtaining an independent estimate of statistical error and we show how blocking can reduce it further. Further discussion shows how orthogonality eliminates mutual factor biases. The chapter moves on to consider how to mute certain adulterating effects including hysteresis and lurking factors and how to validate analytical integrity with residuals plots. For looking at many factors with few experiments we introduce screening designs such as simplex and highly fractionated designs. The reader then learns how random and fixed effects differ and how they affect the analysis. To show how one may assess curvature in factor space a discussion of second-order designs follows. The chapter concludes by considering the sequential assembly of the various experimental designs. 191 2006 by Taylor Francis Group LLC 192 Modeling of Combustion Systems A Practical Approach Some Statistics A statistic is a descriptive measure that summarizes an important property of a collection of data. For