Chatter avoidance in the milling of thin floors with bull-nose end mills: Model and stability diagrams

The milling of thin parts is a high added value operation where the machinist has to face the chatter problem. The study of the stability of these operations is a complex task due to the changing modal parameters as the part loses mass during the machining and the complex shape of the tools that are used. The present work proposes a methodology for chatter avoidance in the milling of flexible thin floors with a bull-nose end mill. First, a stability model for the milling of compliant systems in the tool axis direction with bull-nose end mills is presented. The contribution is the averaging method used to be able to use a linear model to predict the stability of the operation. Then, the procedure for the calculation of stability diagrams for the milling of thin floors is presented. The method is based on the estimation of the modal parameters of the part and the corresponding stability lobes during the machining. As in thin floor milling the depth of cut is already defined by the floor thickness previous to milling, the use of stability diagrams that relate the tool position along the tool-path with the spindle speed is proposed. Hence, the sequence of spindle speeds that the tool must have during the milling can be selected. Finally, this methodology has been validated by means of experimental tests.

Lecture by Terry Gross, given at Florida International University, February 27, 2004

Introduction by Dahlia Morgan. Terry Gross talks about her interview style and shares stories from her past interviews.

Perturbative Ward identities for Yang-Mills field theory stochastically quantized

%'e compute the divergent part of the three-point vertex function of the non-Abelian Yang-Mills gauge field theory within the stochastic quantization approach to the one-loop order. This calculation allows us to find four renormalization constants which, together with the four previously obtained, verify, to the calculated order, some Ward identities.

Max Reger Symposium UW School of Music in conjunction with St. Mark's Cathedral Dr. Carole Terry Wyatt Smith, co-directors November 11-12, 2016

Concert Program

Energy consumption and energy efficiency in olive oil mills: case studies in Portugal and Spain in the frame of TESLA project

TESLA project (Transfering Energy Save Laid on Agroindustry) financed by the European Commission, had the main goals of evaluating the energy consumption and to identify the best available practices to improve energy efficiency in key agro-food sectors, such as the olive oil mills. A general analysis of energy consumptions allowed identifying the partition between electrical and thermal energy (approximately 50%) and the production processes responsible for the higher energy consumptions, as being the in the mill and paste preparation and the phases separation. Some measures for reducing energy waste and for improving energy efficiency were identified and the impact was evaluated by using the TESLA tool developed by Circe and available at the TESLA website.

Páginas de un diario sobre acontecimientos en Villa Mills durante el conflicto armado de 1948

ResumenEste diario fue amablemente enviado a la Revista de Historia por la antropóloga Dra. María Eugenia Bozzoli, miembro de la Academia de Geografía e Historia de Costa Rica, en el mes de diciembre de 2005. Como explicó Bozzoli en esa ocasión, el documento había sido entregado años atrás a esa Academia por el señor Tomás M. Zeledón, quien adjuntó una carta de presentación explicando cómo había llegado el diario a sus manos y quién era R. J. Phillips. Ambos documentos quedaron archivados en la academia hasta que años más tarde, a instancias de Bozzoli, el documento fue digitado y enviado a la Revista de Historia. Aunque desconocemos qué ha sucedido con el señor R. J. Phillips, consideramos que la publicación tanto de su diario como de la carta de Tomás M. Zeledón es oportuna e importante.