A trigonometric approach to quaternary code designs with application to one-eighth and one-sixteenth fractions
The study of good nonregular fractional factorial designs has received significant attention over the last two decades. Recent research indicates that designs constructed from quaternary codes (QC) are very promising in this regard. The present paper shows how a trigonometric approach can facilitate a systematic understanding of such QC designs and lead to new theoretical results covering hitherto unexplored situations. We focus attention on one-eighth and one-sixteenth fractions of two-level factorials and show that optimal QC designs often have larger generalized resolution and projectivity than comparable regular designs. Moreover, some of these designs are found to have maximum projectivity among all designs.
The Stepwise Response Refinement Screener (SRRS) and its Applications to Analysis of Factorial Experiments
Two-level supersaturated designs are very useful in the screening experiments and the common goal is to identify sparse but dominant active factors with low cost. Recently, a new analysis procedure called the Stepwise Response Refinement Screener (SRRS) method is proposed to screen important effects. This paper extends this method to the two-level nonregular fractional factorial designs. The applications to several reallife examples suggest that the SRRS method is able to retrieve similar results as the existing methods do. Simulation studies show that compared to existing methods in the literature, the SRRS method performs well in terms of the true model identification rate and the average model size.
Compressive and flexural properties of hemp fiber reinforced concrete
The compressive and flexural properties of hemp fiber reinforced concretes (FRC) were examined in this paper. Natural hemp fiber was mixed using dry and wet mixing methods to fabricate the FRC. Mechanical properties of the FRC were investigated. The main factors affecting compressive and flexural properties of the FRC materials were evaluated with an orthogonal test design. Fiber content by weight has the largest effect. The method for casting hemp FRC has been optimised. Under the optimum conditions, compressive strength increased by 4 %, flexural strength increased by 9 %, flexural toughness increased by 144 %, and flexural toughness index increased by 214 %.