Systematic investigation of the Friction Stir Welding (FSW) process shows that a fixed rotational velocity and feed rate may not yield uniform mechanical properties along the length of a weldment. Nevertheless, correlations between process parameters and post-weld material properties have successfully demonstrated that peak temperature and cooling rate drive post-weld properties. There have been many reported methodologies for controlling friction stir welding, with varying degrees of cost to implement and effectiveness. However, comparing data from uncontrolled FSW of AA 6111-T4 sheet with controlled FSW at temperatures ranging from 375 °C to 450 °C demonstrates that a simplified methodology of a single-loop PID controlling with spindle speed may be used to effectively control temperature. This methodology can be simply used with any machine that already has the ability to actively control spindle speed, and has been previously shown to be able to be auto-tuned with a single weld. Additionally, implementation of this method compared to uncontrolled FSW in AA6111 at linear weld speeds of 1-2 meters per minute showed improved mechanical properties and greater consistency in properties along the length of the weld under temperature control. Further results indicate that a minimum spindle rpm may exist above which tensile specimens did not fracture within the weld centerline, regardless of temperature. This work demonstrates that a straight-forward, PID-based implementation of temperature control at high weld rates can produce high quality welds with auto-tuned gains. This method also shows promise in application to other processes in the Friction Stir family, and preliminary results in an application to the Additive Friction Stir Deposition (AFSD) process are also presented.

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Matrices of Vision is a sonic deconstruction of a higher education dataset compiled by the influential Swedish higher education authority Universitetskanslersämbetet (UKÄ). The title Matrices of Vision and project theme is inspired by Indigenous cyberfeminist, scholar and artist Tiara Roxanne’s work into data colonialism. The method explores how practical applications of sound and theory can be used to meditate on political struggles and envision emancipatory modes of creation that hold space through a music-making practice. The artistic approach uses just intonation as a system, or grid of fixed points, which it refuses. The pitch strategy diverges from this approach by way of its political motivations: it disobeys just intonation’s rigid structure through practice and breaks with its order as a way to explore its experiential qualities. The approach seeks to engage beyond the structures designed to regulate behaviors and ways of perceiving and rather hold space for a multiplicity of viewpoints which are explored through cacophony, emotion and deep listening techniques.

The judgment that a given event is epistemically improbable is necessary but insufficient for us to conclude that the event is surprising. Paul Horwich has argued that surprising events are, in addition, more probable given alternative background assumptions that are not themselves extremely improbable. I argue that Horwich's definition fails to capture important features of surprises and offer an alternative definition that accords better with intuition. An important application of Horwich's analysis has arisen in discussions of fine-tuning arguments. In the second part of the paper I consider the implications for this argument of employing my definition of surprise. I argue that advocates of fine-tuning arguments are not justified in attaching significance to the fact that we are surprised by examples of fine-tuning.

No description available.

The ability of populations to continually respond to directional selection even after many generations instead of reaching response plateaus suggests the presence of mechanisms for rapidly generating novel adaptive variation within organismal genomes. The contributions of cis regulation are now being widely studied. This study details the contributions of one such mechanism capable of generating adaptive genetic variation through transcribed microsatellite mutation. Microsatellites are abundant in eukaryotic genomes, exhibit one of the highest known mutation rates; and mutations involve indels that are reversible. These features make them excellent candidates for generating variation in populations. This study explores the functional roles of transcribed microsatellites in Helianthus annuus (common sunflower). More specifically, I explored the role of microsatellites as agents of rapid change that act as “tuning knobs” of phenotypic variation by influencing gene expression in a stepwise manner by expansions and contractions of the microsatellite tract. A bioinformatic study suggests that selection has favored expansion and maintenance of transcriptomic microsatellites. This inference is based on the non-random distribution of microsatellites, prevalence of motifs associated with gene regulation in untranslated regions, and the enrichment of microsatellites in Gene Ontologies representing plant response to stress and stimulus. A population genetics study provides support for selection on these transcribed microsatellites when compared to anonymous microsatellites that were assumed to evolve neutrally. The natural populations utilized in this study show greater similarity in allele frequencies, mean length, and variance in lengths at the transcribed microsatellites relative to that observed at anonymous microsatellite loci. This finding is indicative of balancing selection, and provides evidence that allele lengths are under selection. This finding provides support for the tuning knob hypothesis. The findings of a functional genomic study with regard to the tuning knob hypothesis are ambiguous. No correlation between allele lengths and gene expression was detected at any of three loci investigated. However, the loci utilized exhibited narrow ranges in length. The tuning knob hypothesis implies that similar allele lengths are likely to exhibit similar gene expression levels. Hence, variation in the populations studied may be tracking the optimal gene expression levels.

In surveys, one may face the problem of influential units at the estimation stage. A unit is said to be influential if its inclusion or exclusion from the sample has a drastic impact on the estimates. This is a common situation in business surveys as the distribution of economic variables tends to be highly skewed. We study and examine some commonly used estimators and predictors of a population total and propose a robust estimator and predictor based on an adaptive tuning constant. The proposed tuning constant is based on the concept of conditional bias of a unit, which is a measure of influence. We present the results of a simulation study that compares the performance of several estimators and predictors in terms of bias and efficiency.

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This paper presents the results of a study on exhaust manifold design for a NASCAR Restrictor plate internal combustion engine. A computer simulation model was developed using Ricardo WAVE software. WAVE is a computer-aided engineering code developed by Ricardo to analyze the dynamics of pressure waves, mass flows and energy losses in ducts, plenums and the intake and exhaust manifolds of various systems and machines. [1] The model was validated against experimental data from a current NASCAR Winston Cup restrictor plate motor. The parameters studied have been exhaust manifold diameters and lengths. A response surface analysis of the simulation output followed. The analysis of results shows the design parameters of the existing exhaust manifold are not optimized. The findings from these studies are used to derive exhaust system design guidelines which define optimum exhaust system geometry to maximize average Brake Horsepower over a given powerband for a restrictor plate NASCAR engine.

The motivation behind this thesis is to consolidate and evaluate the most common Proportional Integral Derivative (PID) controller tuning techniques used in industry. These are the tuning techniques used when the plant transfer function is not known. Many of these systems are poorly tuned because such consolidated information is not easily found in one single source such as this thesis. Once one of the tuning methods are applied almost always there will be further fine tuning needed to bring the system into the required design criteria. The purpose here is to find out which tuning technique will yield the lowest percent overshoot and the shortest settling time for all situations. This will give the engineer a good starting point; to minimally further adjust parameters to achieve the desired design criteria. There will also be discussion on the various algorithms used in industry. Four tuning methods will be evaluated based on their ability to control different style plants. The comparison criteria will be percent overshoot and settling time for an applied step input. The tuning methods chosen were the Ziegler-Nichols Open Loop method, the CHR method for 0% overshoot, the Ziegler-Nichols Closed Loop method, and the Rule of Thumb method. It is shown that for a second order plant with a lag and pure integration in its transfer function, the Open Loop method yielded the lowest results in terms of percent overshoot, yet the Closed Loop method had the shortest settling time. For systems of higher order than two it was shown that the CHR method gave the best performance however as the order increased the Closed Loop method gave a shorter settling time. For systems of higher order with varying lags in series the CHR method gave the best results. The Rule of thumb method usually gave similar results to that of the Closed Loop method; however for higher order systems the Rule of Thumb method gave less percent overshoot but with a longer settling time than the Closed Loop method. Since these tuning methods are used when the plant transfer function is not known, and none of the rules were found to give consistently the lowest percent overshoot, and settling time for all plants tested, there can not be a recommendation as to which method an engineer should choose to use. If the plant transfer function is known or can be reasonably modeled then the following recommendations can be followed. When tuning systems with pure integrations in their transfer function the Open Loop or Closed Loop method be used. When tuning systems of order higher than two the CHR or Closed Loop method should be used, however with high order systems with varying lags the CHR method should be used. It is the responsibility of the engineer to know how and when to implement each of the tuning rules properly.