Modelling tribology of slider and disk in a computer hard drive system

Issues of wear and tribology are increasingly important in computer hard drives as slider flying heights are becoming lower and disk protective coatings thinner to minimise spacing loss and allow higher areal density. Friction, stiction and wear between the slider and disk in a hard drive were studied using Accelerated Friction Test (AFT) apparatus. Contact Start Stop (CSS) and constant speed drag tests were performed using commercial rigid disks and two different air bearing slider types. Friction and stiction were captured during testing by a set of strain gauges. System parameters were varied to investigate their effect on tribology at the head/disk interface. Chosen parameters were disk spinning velocity, slider fly height, temperature, humidity and intercycle pause. The effect of different disk texturing methods was also studied. Models were proposed to explain the influence of these parameters on tribology. Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) were used to study head and disk topography at various test stages and to provide physical parameters to verify the models. X-ray Photoelectron Spectroscopy (XPS) was employed to identify surface composition and determine if any chemical changes had occurred as a result of testing. The parameters most likely to influence the interface were identified for both CSS and drag testing. Neural Network modelling was used to substantiate results. Topographical AFM scans of disk and slider were exported numerically to file and explored extensively. Techniques were developed which improved line and area analysis. A method for detecting surface contacts was also deduced, results supported and explained observed AFT behaviour. Finally surfaces were computer generated to simulate real disk scans, this allowed contact analysis of many types of surface to be performed. Conclusions were drawn about what disk characteristics most affected contacts and hence friction, stiction and wear

Choice Experiments: Application to Air Quality Policy Options and Investigation of Method\u27s Incentive Compatibility

More than half of all Americans live in areas that violate at least one of the U.S. Environmental Protection Agency’s air quality standards for ground-level ozone and fine particulate matter. The majority of these areas have many options to come into compliance with the standards, such as requiring vehicle inspection/maintenance programs, changing gasoline blends, and requiring additional controls on power plants. Chapter 1 explores the use of conjoint-based choice experiments to assist local policymakers in determining the most beneficial policy strategy using the case study of Knoxville, Tennessee. Given that different policy actions pass costs onto households in different ways and that households may have varying preferences regarding how they pay those costs, I test whether willingness to pay for air quality improvements is sensitive to the method of payment. Potential heterogeneity of preferences is modeled through a mixed logit specification. Results indicate positive willingness to pay among Knoxville area residents for improvements in air quality, with vehicle inspection and an increase in the price of gasoline as the preferred payment vehicles over an increase in the electricity bill. Chapter 2 investigates the underlying incentive compatibility of choice experiments with tests of the mechanism in an induced value laboratory setting. The theoretical properties of both dichotomous choice and trichotomous choice elicitation formats are explored under plurality voting rules and more generally under the assumption that the respondent perceives her decision to have some influence on the outcome. Results indicate that certain belief structures can lead to incentive compatible outcomes in a trichotomous choice format, depending on how a respondent believes the agency will incorporate respondent decisions into the provision of a public good. In addition, the trichotomous choice treatments had fewer deviations from theory and were less subject to status quo bias than treatments with dichotomous choice questions. Implications for the design of choice experiments and contingent valuation surveys are discussed

Continuum of Alliance: A Proposed Model for Understanding the Relationship Between Adult Education and Human Resource Development

The relationship between Adult Education and Human Resource Development has been modeled or described in various ways but continues to evolve. Building on existing conceptions, we present an alternative model for understanding the fields as distinct and yet complementary

The Commons: Tools for Reading, Writing, and Rhetoric

The Commons: Tools for Reading, Writing, and Rhetoric gives instructors and students of college writing courses a single source for information on metacognitive critical reading, rhetorical awareness, and MLA formatting basics as well as interesting and relevant reading and viewing content. Its approach is interdisciplinary, bringing in material from ecology, sociology, psychology, technology, popular culture, political science, cultural studies, and literature. Each essay, website, video, infographic, and poem has been carefully chosen to speak to the Eastern Kentucky University community, but everyone can find something that speaks to our common human experience and our need to communicate and connect with one another.https://encompass.eku.edu/ekuopen/1003/thumbnail.jp

Collaboration and Cognitive Skills in the Workplace: Results from the PIAAC Survey

Using the PIAAC survey, this study examined social characteristics of work and cognitive skills. Results negatively associated collaboration at work and PIAAC scores, contradicting current thinking on workplace interactions