Abrasion monitoring and automatic chatter detection in cylindrical plunge grinding

Using conventional grinding wheels, wheel-sided chatter vibration is one of the limiting factors in terms of productivity and surface finish. Initial vibration related to the dynamic behavior of the machine tool copy on the grinding wheel and its amplitude amplifies by abrasion. To ensure high workpiece quality many expensive truing cycles are needed. In this context, we suggest a new set-up for the automatic chatter detection and elimination for external cylindrical grinding machines, reducing not only the high amount of true running cycles, but also improving the efficiency. In order to suppress the generation of the waviness on the grinding wheel the effect has to be identified during an early stage of its development. Therefore, a grinding machine is equipped with different types of sensors, i.e., eddy current, force, acoustic emission, acceleration sensors, and a tactile probe. Experimental results show, that exclusively measuring the displacement at the workpiece is sufficient for online computing wheel's waviness. Based on a model of the grinding process the other redundant sensors are used for validation. In addition, a robust online chatter detector based on the wavelet transformation is developed recognizing an instable grinding process. This model-based detection and estimation of waviness delivers solid results, it should be used for suppression of chatter in further work

Estimation of Dynamic Grinding Wheel Wear in Plunge Grinding

Using conventional grinding wheels, self-excited vibrations are one of the most limiting factors in terms of productivity and process stability in cylindrical plunge grinding. Depending on the dynamic behavior of the workpiece and machine, vibrations of the workpiece copy on the grinding wheel's surface, caused by uneven wear. This results in increasing waviness of the grinding wheel and by that, increasing workpiece vibration. Electromagnetic actuators are capable of influencing the dynamic process forces and therefore, the wear. The authors pursue the objective, to achieve an active control of the tool wear for low workpiece vibration and high workpiece quality. Therefore, a tool-wear-model which enables the estimation of the grinding wheel's surface is proposed. The parameterization of the model is realized carrying out a set of reference processes with subsequent identification. Aside from the dynamic tool wear, the workpiece oscillation is simulated by the model. A Kalman Filter is utilized to adjust the model onto the current process using the measured workpiece oscillation. Thus, it is possible to achieve an online estimation of the wave amplitude and phase angle on the grinding wheel's surface as well as their progression. © 2017 The Authors

Specialists, Coaches, Coordinators, Oh My! Looking Back and Looking Forward on the Roles and Responsibilities of Specialized Literacy Professionals

This article briefly reviews the past, present, and future of the related (but distinct) roles of literacy specialists, coaches, and coordinators in the United States. Connections are made to the International Literacy Association\u27s 2017 Standards for the Preparation of Specialized Literacy Professionals (SLPs) as well as recent survey research further illustrating the variety of roles played by SLPs in schools and how principals view the impact of SLPs

Principals’ Perspectives on the Roles of Specialized Literacy Professionals

Elementary and secondary principals were surveyed to better understand their perceptions of the roles and impact of specialized literacy professionals (e.g., reading specialists, coaches) in their schools. A 32-question survey was completed by 103 Pennsylvania principals across elementary and secondary school contexts. Findings include distinct differences reported between roles of reading/literacy specialists and coaches, with few differences noted within roles, across elementary and secondary levels. The frequency and type of specialized literacy professional activities aligned with those principals deemed most important to literacy program improvement. Results indicated that surveyed principals viewed their specialized literacy professionals as having an important influence on literacy teaching and learning. The results have implications for those who prepare specialized literacy professionals and those who employ them. These findings corroborate and update earlier studies of specialized literacy professionals that described their multiple roles, including that of sharing in the leadership of the school’s literacy program

Preparing reading/literacy specialists to meet changes and challenges: International Literacy Association’s Standards 2017

Lead writers and co-chairs of the International Literacy Association’s Standards 2017provide a hands on guide to using updated standards for the preparation of reading/literacy specialists. Authors share key changes in content, supporting explanations with updated references, and implications for program faculty, state policymakers, and specialist candidates. Standards 2017 adds a new seventh standard for Practicum/Clinical Experiences and sets high expectations for programs to incorporate candidate experiences with technology, diversity, collaboration, and advocacy. Processes to work with colleagues to design or re-design, implement, and evaluate programs are discussed

The 10.0 Guide to Reducing the Risk of Lower-Extremity Injuries Among Female NCAA Gymnasts

An Injury Prevention Program Designed to Reduce the Risk of Lower-Extremity Injuries within Women's NCAA Gymnastics Teams. Grounded in a behavior change perspective using an integrated theory model that combines the Health Belief Model and the Theory of Planned Behavior, the culmination of this project is a lower-extremity injury prevention program that's tailored to the needs of female NCAA gymnasts. To encourage more coach adoption and implementation, the injury prevention program is housed in an all-inclusive infographic and associated website link, allowing for efficient accessibility and effective functionality

Teachers as Decision Makers: Narratives of Power in an Era of Standards

This article focuses on teachers as decision makers with regard to curriculum and teaching. It explains how some teachers in the Pittsburgh area, tired of losing precious learning opportunities to the old prescribed curriculum, decided to provide their students with learning experiences in which the curriculum became a living shape; created by the children, teachers, and parents; rather than a static set of policies. It refl ects on what important things can be taught and learned in schools that will endure. We hope to explore the idea of what happens when a teacher’s curricular choices run against those ideas and habits put forth by schools and others involved in children’s schooling. As John Dewey reminds us, renewing self and community best occurs in a democratic society, in which justice and caring are central. These ideas only occur in schools where the central fi gures - the teachers - shape, foster, and enrich the lives that have been entrusted to them by the parents. The success and promise of these teachers is to expose children to a multitude of experiences that will help shape their life stories and one day enact those democratic ideals in everyday practice when they chose to vote, raise a child, live within a neighborhood, chose whether to attend religious services, and in particular, when they are asked to judge themselves as democratic citizens. Regardless of one’s background, place, or economic reality, the successful attainment of skills and fundamentals only occurs when the intellectual and emotional growth of that individual is respected, cared for, and enhanced, and this can only occur when the dedication, caring, talent, and intelligence of the teacher are allowed to fl ourish.O presente artigo focaliza os professores como tomadores de decisão no que se refere a currículo e ensino. Ele explica como alguns professores que lecionam em escolas na região de Pittsburgh, cansados de perder preciosas oportunidades de aprendizagem para os ultrapassados modelos curriculares vigentes, decidiram oferecer a seus alunos experiências de aprendizagem através de um currículo que tomou uma forma viva; foi criado com a participação das crianças, professores e pais, e não mais por conjuntos estáticos de políticas. O artigo refl ete ainda sobre quais temas importantes podem ser ensinados e aprendidos nas escolas que abraçarão o futuro. Esperamos explorar a idéia daquilo que ocorre quando as escolhas curriculares do professor são contrárias às idéias e hábitos estabelecidos pela escola e por outras instituições envolvidas na educação da criança. Como lembra John Dewey, a renovação individual e comunitária ocorre melhor em uma sociedade democrática, uma sociedade em que justiça e assistência são essenciais. Estas idéias ocorrem somente em escolas em que a fi gura central – o professor – dá forma, nutre e enriquece a vida daqueles que lhes são entregues em confi ança pelos pais. O sucesso e a promessa destes professores é expor as crianças a uma multiplicidade de experiências que ajudarão a dar forma às suas histórias de vida e, algum dia, trazer à tona ideais democráticos na prática cotidiana de escolha do voto, criação de fi lhos, convivência com vizinhos, escolhas religiosas, e, especifi camente, quando lhes for solicitado julgamento como cidadãos democráticos. Independente de formação, origem, realidade econômica, a aquisição bem sucedida de habilidades e de uma base sólida só ocorre quando o crescimento intelectual e emocional do indivíduo é respeitado, protegido e enfatizado, e isto só pode ocorrer se for permitido que fl oresçam a dedicação, o cuidado, o talento e a inteligência do professor

An Active Damping Method for Chatter Vibration in Plunge Grinding Using Electromagnetic Actuators

AbstractUsing conventional grinding wheels, self-excited vibrations are one of the most limiting factors in terms of productivity and process stability in cylindrical plunge grinding. Depending on the dynamic behavior of the workpiece and machine, workpiece vibration copy on the grinding wheel's surface, caused by uneven wear. This results in increasing waviness and, therefore, increasing workpiece vibration. In this context, an active vibration control, using a self-built magnetic actuator to influence the tool wear, is presented. The limits and possibilities of this influence are examined in this paper, i. e. the generation and reduction of waves on the grinding wheel. Furthermore, the prevention of chatter vibration and its robustness against parameter variation is analyzed and presented

Establishment and characterization of a new human urinary bladder carcinoma cell line (PS-1).

An epithelioid cell line (PS-1) has been established from a transitional cell cancer derived from human urinary bladder. Subcutaneous injection of the epithelioid cells into weanling athymic nude mice induced solid tumors histologically similar to the original tumor. A cell line was also established from a tumor induced in the athymic nude mouse (PS-1, T-1). Both cell lines exhibited essentially identical growth characteristics and formed a monolayer growth of epithelioid cells in culture. Electron microscopic studies confirmed epithelioid morphology. No fibroblastoid elements were observed. Chromosomal analysis revealed heteroploidy with persistent marker chromosomes; all cells contained a Y chromosome. The presence of tumor-specific antigen(s) in PS-1 cells was suggested by microcytotoxicity assays with peripheral allogeneic lymphocytes from other transitional cancer cell patients. Sera of urinary bladder cancer patients reacted with nuclear antigens of the established cells