Browsing by Subject "Experimental design"
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Item Design of an engineering experiment and data driven design in secondary education(2013-08) Fallin, Patrick Timothy; Allen, David T.Pre-tests and post tests were used to assess the effectiveness of an engineering high school unit on experimental design and data driven design. The engineering data acquisition unit examined in this report used project based learning to teach the design of an engineering experiment and data driven design as part of the engineering design process. The project consists of the design of a building that can safely withstand an earthquake. Students construct, test and collect data on baseline buildings, with and without load using a shaker table and data acquisition. Students' then design experiments to evaluate design modifications that will meet the customer's needs. Overall, although the number of participants was limited, the survey instruments indicated that understanding of experimental design improved among high school students participating in the unit. Based on this pilot implementation of survey instruments, some of the survey questions were clarified.Item Estimation and testing in the restricted general linear model(Texas Tech University, 1972-05) Hallum, Cecil RalphNot availableItem Experimental and Computational Study of the Inclined Interface Richtmyer-Meshkov Instability(2013-08-12) Mcfarland, Jacob AndrewA computational and experimental study of the Richtmyer-Meshkov instability is presented here for an inclined interface perturbation. The computational work is composed of simulation studies of the inclined interface RMI performed using the Arbitrary Lagrange Eulerian (ALE) code called ARES. These simulations covered a wide range of Mach numbers (1.2 to 3.5), gas pairs (Atwood numbers 0.23to 0.95), inclination angles (30? to 85?), and explored various perturbation types (both inclined interface and sinusoidal). The computational work included the first parametric study of the inclined interface RMI. This study yielded the first scaling method for the inclined interface RMI mixing width growth rates. It was extended to explore the effect of perturbation linearity and identified that a sharp transition in growth regimes occurs for an initial perturbation inclination angle of 75? with angles below (above) this growing faster (slower). Finally a study of the effects of incident shock strength on the refracted shock wave perturbation decay rate is presented. This study examined how the perturbations induced on the transmitted shock front by the RMI decay with time and found that the decay rates follow a power law model, Alpha=Beta?S^(Epsilon). When the coefficients from the power law decay model were plotted versus Mach number, a distinct transition region was found which is likely a result of the post-shock heavy gas velocity transitioning from the subsonic to supersonic range. The experimental portion of this work was conducted using the TAMUFMSTF, completed in May of 2012. This facility uses a variable inclination shock tube, with a modular construction design for incident shock strengths of up to Mach 3.0. It employs optical systems for measuring density and velocity fields simultaneously using the planar laser induced fluorescence and particle imaging velocimetry techniques. The design and construction of this facility is reviewed in detail in chapter 4 of this work. The initial experiments performed in the TAMUFMSTF provided the first known extensive experimental data for an inclined interface RMI. Planar laser Mie scattering images and velocity vectors were obtained for a N_(2)/CO_(2) interface at a 60? inclination angle and an incident shock strength of Mach 1.55. These images have been compared with simulations made using the ARES codes and have been shown to have some distinct differences. Some of these differences indicate that the initial conditions in the experiments deviate from the ideal planar interface. Other differences have revealed features which have not been resolved by the simulations due to resolution limitations.Item Nonparametric methods for pairwise comparisons in the randomized complete block design(Texas Tech University, 1998-12) Barefield, Eric W.The main focus of this investigation is to verify the robustness of validity of these tests. By robustness of validity, it is meant the stability of the Type I error rate for small designs as well as conditions under which some of the underlying assumptions are violated. For methods that produce valid tests, further investigations with respect to power are meaningful. Since many nonparametric methods use large sample approximation theory, it may be expected that these methods will perform better as n, the number of blocks, increases. As the number of treatments, p, gets larger, it becomes harder to reject the null hypothesis since this increases the critical value. As we will see, some design structures make rejection of the null hypothesis impossible for certain methods. The methods of interest include the sign statistic, signed rank statistic, rank sum statistic (Aligned Rank statistic using separated rankings and uniform scores). Aligned-Rank Transform, Within-Block ranking, and least squares.Item Page's statistic in balanced incomplete block designs(Texas Tech University, 1995-08) Duran, Benjamin S.A block is a collection of experimental units that are as nearly alike as possible relative to the extraneous variable. Each treatment is then randomly assigned to one experimental unit within each block. If the experimental units within blocks are relatively alike and units in different blocks are relatively different, then the randomized complete block design is usually more sensitive to differences in treatment means than the one-way classification design, a design which assumes all experimental units are relatively homogeneous. Often, one may not be able to run all of the treatments in each block. Possible reasons may be due to shortages of experimental units, the physical size of the blocks, or that the cost is too great to use a complete block design. Assuming a complete block design cannot be used, the designer must turn to alternative methods. One popular choice is the randomized incomplete block design, a design which allows for analyzing treatment effects without running every treatment within each block. By assigning treatments in a balanced manner among the experimental units in a block, accurate analysis of treatment effects can be accomplished while reducing the number of treatment runs needed in each block. When performing a normal-theory F test to analyze the treatment effects, the experimenter must assume that the error variables are normally distributed. However, a design could occur in which the normality assumption is invalid, and the designer may wish to use a distribution-free procedure. Nonparametric methods for determinig differences in treatment effects have been proposed for complete randomized block designs by Friedman [3] and for balanced incomplete block designs by Durbin [2]. An analyst may be interested in detecting some specific relationship among the treatment effects. In particular, one may be interested in the simple order alternative, which is useful for testing treatment effects versus a control. For the complete block design, a statistic for the simple order alternative was proposed by Page [5]. We intend to use Page's statistic with incomplete block designs while creating exact distributions for small designs and simulated distributions for larger designs. In the absence of exact or simulated tables, the normal approximation can be used to make a decision with respect to the rejection of the null hypothesis.