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Eibar, Spain

Bediaga I.,IK | Mendizabal X.,SORALUCE S. Coop. | Arnaiz A.,Diagnostics and Prediction Unit | Munoa J.,University of Navarra
IEEE Instrumentation and Measurement Magazine

Fault detection and diagnosis of ball bearings has always been a challenge when monitoring rotating machinery. Specifically, bearing diagnostics have seen extensive research in the field of fault detection and diagnosis. This article reviews traditional algorithms used to detect and diagnose faulty bearings in heavy-duty milling machine tool spindle heads. Different kinds of faults have been created deliberately on the bearings of a test spindle head. The prediction effectiveness of several detection methods are tested when faults are in different stages of development. © 1998-2012 IEEE. Source

Dombovari Z.,Budapest University of Technology and Economics | Munoa J.,IK | Stepan G.,Budapest University of Technology and Economics
Procedia CIRP

In this study, the stability properties of general milling processes are summarized and compared to each other considering different special tool geometries. This general model can deal with any kind of flute geometry and with non-proportional damping using the semi-discretization method. A real-case experimental tip2tip modal analysis of a carbide milling tool is taken, which serves as the reference dynamics for the stability calculations. A fitting algorithm is used to extract the modal parameters of the corresponding non-proportionally damped system that is given directly in first order representation. The asymptotic stability of the stationary solution of the resulting time-periodic parametrically excited and time-delayed system is investigated by the semi-discretization algorithm. The stability properties of variable pitch, serrated and variable helix tools are compared with the one of the conventional helical tool. © 2012 The Authors. Source

Presser M.,Alexandra Instituttet A S | Larranaga M.,IK
2015 International Conference on Recent Advances in Internet of Things, RIoT 2015

This paper describes the work performed within the URB-Grade project. The URB-Grade project designs, develops and validates a Platform for Decision Support that will allow the city authorities and utilities to promote and choose the correct actions. This will allow upgrading a district to become more energy efficient, cost effective and to increase comfort for its citizens in a District as a Service Platform (DaaS Platform) approach. This paper describes the methodology taken to specify the variables that affect the energy consumption of a district and the actions to reduce them, the global architecture of the platform based on the Service Oriented Architecture paradigm, and the impact that the use of the tool intends to achieve. © 2015 IEEE. Source

Calzado E.M.,University of Alicante | Villalvilla J.M.,University of Alicante | Boj P.G.,University of Alicante | Quintana J.A.,University of Alicante | And 4 more authors.
Applied Physics Letters

It is shown that the optical pump power (or energy) density thresholds required to obtain lasing from organic second-order distributed feedback lasers, increase when the excitation area (A) is smaller than a certain value (A crit). So, in order to obtain the minimum possible thresholds and to ensure that they constitute adequate quantities for comparison purposes, the condition A > Acrit should be fulfilled. Results also indicate that when A Acrit (Acrit ∼ 0.1 mm2 for the devices studied here), the operational device lifetime, which depends mainly on the pump power (or energy) density, becomes drastically reduced. © 2012 American Institute of Physics. Source

Gonzalez A.G.,University of Santiago de Compostela | Zugasti E.,IK | Anduaga J.,IK
Key Engineering Materials

This paper presents a method to detect and identify damage in a laboratory offshore wind turbine support structure. The structure consists of three different parts: the jacket, the tower and the nacelle. The jacket is a lattice structure joined with several bolts. The tower consists of three different sections joined by bolts. The nacelle is composed of a single piece. The different parts are also joined with bolts. The damage in the structure is simulated by loosening some of the bolts in the jacket. Two damage detection algorithms, namely AutoRegressive methods and NullSpace methods, have been tested in a primitive variation of this structure without the jacket, obtaining good results. In this paper we present the application of the last damage detection method to the new structure with the jacket and an extension to identification of the damage. © (2013) Trans Tech Publications. Source

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