Analysis of an Ultra-precision Positioning System and Parametrization of Its Structural Model for Error Compensation

Conventional compensation of position errors of machine tools relies only on measured values. Due to this principle it is not always possible to compensate the errors in time, especially dynamic ones. Moreover, the relevant control variables cannot always be measured directly. Thus, this approach proves to be insufficient for high precision applications. In this context, a model-based error prediction allows for minimal position errors. However, ultra-precision applications set high demands for the models' accuracy. This paper presents the design of an accurate and real time-capable structural model of an ultra-precision positioning system. The modeling method for the developed ultra-precision demonstrator is shown and the initial parameter identification is presented. © 2017 The Authors. Published by Elsevier B.V.DFG/FOR/184

Analysis of airplane boarding via space-time geometry and random matrix theory

We show that airplane boarding can be asymptotically modeled by 2-dimensional Lorentzian geometry. Boarding time is given by the maximal proper time among curves in the model. Discrepancies between the model and simulation results are closely related to random matrix theory. We then show how such models can be used to explain why some commonly practiced airline boarding policies are ineffective and even detrimental.Comment: 4 page

Motivations and Locavore Tendencies: A preliminary visitor study of Lexington, Kentucky craft breweries

The emergence of craft beer in recent years has contributed to increased participation in beer tourism. However, there is a dearth of literature on brewery visitors. A key first step in researching beer tourism is to obtain an initial understanding of who is visiting breweries and why. This may provide information to better market target audiences. This information provides valuable insight for Kentucky brewery management and operations. Although this research concentrates on one state, it may enhance experiences at breweries in other states, increasing initial and repeat visitation. This study hopes to bring forth more information similar to the visitor profile made by Plummer, Telfer, Hashimoto, and Summers (2005) and to help brewery managers to continue providing experiences that will gain repeat customers. Kentucky brewery patron’s motivations, likeliness to shop local, intent to visit breweries in the future, and sociodemographic variables that may provide insight related to these constructs were examined in this study. Four breweries were utilized as research sites with 345 of 353 brewery visitors, a response ratio of 97%, agreeing to participate. The researchers found that visiting a brewery was not the main reason a majority of visitors were traveling, preference for craft beer was higher than for national beer brands, respondents were predominantly white, and almost half of respondents had a bachelor’s degree. As the craft brewery industry considers the future, visitor profiles and motivations will help guide brewery management to target marketing efforts in ways that position the industry for growth and community impact

Solitary waves on falling liquid films in the inertia-dominated regime

We offer new insights and results on the hydrodynamics of solitary waves on inertia-dominated falling liquid films using a combination of experimental measurements, direct numerical simulations (DNS) and low-dimensional (LD) modelling. The DNS are shown to be in very good agreement with experimental measurements in terms of the main wave characteristics and velocity profiles over the entire range of investigated Reynolds numbers. And, surprisingly, the LD model is found to predict accurately the film height even for inertia-dominated films with high Reynolds numbers. Based on a detailed analysis of the flow field within the liquid film, the hydrodynamic mechanism responsible for a constant, or even reducing, maximum film height when the Reynolds number increases above a critical value is identified, and reasons why no flow reversal is observed underneath the wave trough above a critical Reynolds number are proposed. The saturation of the maximum film height is shown to be linked to a reduced effective inertia acting on the solitary waves as a result of flow recirculation in the main wave hump and in the moving frame of reference. Nevertheless, the velocity profile at the crest of the solitary waves remains parabolic and self-similar even after the onset of flow recirculation. The upper limit of the Reynolds number with respect to flow reversal is primarily the result of steeper solitary waves at high Reynolds numbers, which leads to larger streamwise pressure gradients that counter flow reversal. Our results should be of interest in the optimisation of the heat and mass transport characteristics of falling liquid films and can also serve as a benchmark for future model development

Exercising heart failure patients:cardiac protection through preservation of mitochondrial function and substrate utilization?

Current heart failure (HF) therapy remains unable to substantially improve exercise capacity. Studies have shown that exercise training has beneficial effects on the heart in both health and disease. How mitochondria respond to exercise in this setting has, however, received less attention in literature. These beneficial effects may include protective changes in mitochondrial function and adaptations in substrate utilization. This review describes exercise-induced changes in cardiac metabolism, including changes in mitochondrial function and substrate utilization and their effects on cardiac function. We conclude that exercising HF patients can improve mitochondrial function and optimize substrate utilization, eventually improving or restoring cardiac function. This suggests that exercise itself should be incorporated in the HF treatment plan, to improve cardiac function and in term exercise capacity. Extending knowledge on mechanisms by which exercise exerts protective effects could potentially lead to development of therapies directed at improving mitochondrial function and substrate utilization in HF.</p