The influence of laser hardening on wear in the valve and valve seat contact

In internal combustion engines it is important to manage the wear in the valve and valve seat contact in order to minimise emissions and maximise economy. Traditionally wear in this contact has been controlled by the use of a valve seat insert and the careful selection of materials for both the valve and the insert. More recently, due to the increasing demands for both performance and cost, alternative methods of controlling the wear, and the resulting valve recession, have been sought. Using the heating effect of a laser to induce localised phase transformations, to increase hardness and wear resistance, in materials has been used since the 1970s, however it is only in recent years that it has been able to compete with more established surface treatment techniques, particularly in terms of cost, as new laser hardware has been developed. In this work, a laser has been used to treat the valve seat area of a cast iron cylinder head. In order to optimise the laser parameters for use on the head, preliminary tests were carried out to investigate the fundamental wear characteristics of untreated cast iron and also cast iron with a range of laser treatments. Previous work has identified the predominant wear mechanism in the valve and valve seat contact as impact on valve closure. Two bespoke test machines, one for testing basic specimens and one for testing components, were used to identify the laser parameters most likely to yield acceptable results when applied to a cylinder head to be used in a fired dynamometer test. © 2009 Elsevier B.V. All rights reserved

Themes of drawing and digital context: student engagement with theory and practice using the tool of the integrated learning portfolio

This article presents a reflective visual narrative documenting the learning encounters of BA (Hons) Surface Design undergraduates using the Integrated Learning Portfolio (ILP) tool in Year one. Theoretical themes of drawing, digital drawing design practice, and visual design research experientially blended the physical and the virtual learning tools, environments and collaborative culture through this integrated first year route. Parallel theory and practice on specific themes such as ‘drawing lines within the urban landscape’, ‘creating shadow silhouettes’, ‘using the body as a tool for drawing’, and ‘cultivating fortuitous accidents in drawing practice’, created a conceptual space for students to evaluate the future relevance of these drawing experiences within the context of their design programme

A Plea for the Sabbath

The Sabbath presents the most purely religious, and at the same time the least sectarian, of all moral questions. It has, however, been generally regarded under two aspects, and defended on tow distinct if not opposing grounds. One of these may be call the scriptural or theological, the other the physical or secular.https://place.asburyseminary.edu/ecommonsatsdigitalresources/1109/thumbnail.jp

Prevention of Increasing Burnout Levels Among Physicians of Different Specialties and Doctoral Degrees

Burnout rates are steadily increasing among physicians all over the world (Sime, Quick, Saleh, & Martin, 2007). Burnout is defined as high levels of emotional exhaustion (EE), high levels of depersonalization (DP), and low levels of personal achievement (PA) (Ionita, Copotocan, & Copotoiu, S., 2011). These burnout rates are directly correlated with many factors, such as high levels of emotional exhaustion and stress (McManus, Winder, & Gordon, 2002), little experience in the medical field (Keswani, Taft, Coté, & Keefer, 2011), and long work hours which leads to sleep deprivation and fatigue (Jackson, 1999). These moderate to high levels of burnout are detrimental to the health of the physician and ultimately reflect in the dehumanization of doctor-patient relationships (Jackson, 1999)

#Blacklanguagematters: A case study of black identities in an L2 isiXhosa classroom

This paper explores the development of Black identity in a critical and culturally relevant beginner L2 isiXhosa course. While Black students have been a major focus in American education, little attention has gone to their identities in L2 classrooms. In African language courses specifically, Lee (2005) found that Black university students largely enrolled to connect with their African heritage. Van Deusen-Scholl (2003) classified these types of students as learners with heritage motivation. However, there has been little research on how Black students negotiate their historical-cultural heritage in a contemporary L2 classroom. In a case study conducted at the University of Hawaiʻi, four students participated in three twohour isiXhosa lessons designed to be culturally relevant and to critically examine their identities in relation to South African Xhosa culture. Along with survey and lesson discussion data, I interviewed students before and after the course to measure the development of their intersectional identities and perspectives. Drawing on a negotiated syllabus discussion, survey responses, and interviews, I used Rosa and Flores’s (2017) raciolinguistic perspective as a framework to analyze student perceptions of race, gender, and language to understand how the goals of these learners with heritage motivation converged with their intersectional identities and African heritage in an isiXhosa classroom. My findings show that the students developed awareness of their African heritage by shifting their perspectives away from negative outsider perceptions of Black and African communities. Their positive responses to the course relied both on the critical/cultural and linguistic content. This suggests that Black learners with heritage motivation value linguistic acquisition, and benefit from curriculum focused on the connections between Black and African cultures, exclusive of their historically linked oppressions

Assessing Nonresponse Bias by Permitting Individuals to Opt Out of a Survey

The Federal Employee Viewpoint Survey (FEVS) is a Web-based organizational climate survey administered annually by the U.S. Office of Personnel Management. The survey targets full- or part-time, permanently employed civilian personnel from more than 80 U.S. government agencies. Despite increases in the scope, publicity, and uses of FEVS data, its response rate has gradually declined over time. In an effort to gauge the causes for nonresponse, this paper discusses results from an experiment fielded during the 2017 FEVS in which a portion of sampled individuals was given the opportunity to opt out from the survey. Before effectively being added to the “unsubscribe” list, however, the individual was asked to cite the primary reason for choosing not to take the FEVS. Using auxiliary information from the sampling frame, this article argues that inferences based on this item are valuable because opters out are generally representative of the larger pool of nonrespondents

Temporal Perspectives of Nonresponse During a Survey Design Phase

"Invariably, full response is not achieved with a single survey solicitation, and so a sequence of follow-up attempts typically ensues in an effort to mitigate the potentially detrimental effects of nonresponse. Rather than permitting the follow-up campaign to continue indefinitely or until some preset response rate is met, a potentially more efficient alternative is to track a key point estimate in real-time as data is received and alter the survey design phase (i.e., modify the recruitment protocol) once the point estimate stabilizes. The notion of point estimate stability has been referred to as phase capacity in the survey methodology literature, and several methods to detect when it has occurred have been proposed in recent years. Noticeably absent from those works, however, is statistical theory providing insight into how point estimates can change during the course of data collection in the first place. The goal of this paper is to take a first step in developing that theory. To do so, the two established perspectives of survey nonresponse - deterministic and stochastic - are extended to account for the temporal dimension of responses obtained during a survey design phase. An illustration using data from the 2014 Federal Employee Viewpoint Survey is included to provide empirical support for the new theory introduced." (author's abstract

Identifying the barriers to access to higher education for African -American students: Opinions of successful African -American educators

The purpose of this study was to examine past and present social, educational, and financial barriers to African American access to and success within United States higher educational institutions, and identify and recommend ways of ameliorating those barriers for African American students in the future. Based on a comprehensive literature review and analysis of responses to an author-designed survey questionnaire mailed to a cross-section of current United States African American higher education administrators, the study identified and analyzed past and present impacts, on African Americans, of social, educational, and economic factors possibly impeding their higher education entry and success. These included, among others, substandard K through 12 preparation; inadequate academic and social support; insufficient financial planning, resources, and opportunities; and affirmative action-based admissions and financial aid policies and programs (or the lack thereof). The survey questionnaire mailed to U.S. African American higher education administrators contained 12 questions in all, the first six specific and demographically based, the rest open-ended questions on the perceived nature and impact(s) of social, educational, and financial barriers on African American access to and success within higher education. Respondent answers to these twelve questions then formed the basis of information amalgamated for the latter part of the study. A numerical ranking of respondent-identified barriers based on perceived importance, combined with explanations of why respondents deemed particular barriers significant, and finally, respondent suggestions on what might be done to ameliorate each barrier, provided material for the study\u27s conclusions and recommendations

Entrepreneurial support for black (Afro-Caribbean) and Asian construction businesses: Can it enhance their growth?

This thesis investigates challenges encountered by UK Black (Afro-Caribbean) and Asian Construction Businesses (BACBs). It focuses on the effects of UK policies that offer entrepreneurial support to assist BACBs’ survival and growth. Despite significant interest and intensive debates, empirical research has been inconclusive with regards the effectiveness of the implementation of such policies on the survival and growth of BACBs. Moreover, there was no conceptual model or theoretical framework that had been applied in order to aid the understanding of their survival and growth. Hence, the aim of this study is to close this research gap by developing a framework, and to make recommendations for more appropriate support mechanisms to assist in the survival and growth of BACBs. A critical literature review of the effectiveness of support offered by the UK Government led to the development of an integrated model of growth factors that informed both the pilot study and the main questionnaire design. Some of these growth factors were contextual, and so necessitated a qualitative approach. However, because the model was validated through in-depth case studies, the pilot study, main questionnaire and case studies were all undertaken and analysed within an ontology that leaned towards an objective-constructivist perspective, and an interpretivist epistemology. A mixed methodology (qualitative and quantitative) approach was also employed, in order to get a better understanding of the relationships and for robust analyses. The findings indicated that support take-up by the respondents was extremely low. However, support mechanisms of networking and continuous professional development assisted the respondents’ growth. Therefore, when constructive, well organised public support is offered, there is a high probability that it will be taken-up. Policy should be targeted to assist in areas (growth intentions, innovative practices and good human resource management) which impacted on turnover and profits in order to provide sustained growth