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Portolan M.,Bell Labs Ireland | Van Treurent B.,Alcatel - Lucent | Goyal S.,Bell Labs Ireland
Proceedings - International Test Conference | Year: 2010

This paper presents the Open-Circuit Deadlock (OCD), a primitive that allows flexible and scalable securization of a JTAG target, from the cell to the system level. © 2010 IEEE. Source

Bulja S.,Bell Labs Ireland | Mirshekar-Syahkal D.,University of Essex | James R.,University College London | Day S.E.,University College London | Fernandez F.A.,University College London
Microwave and Optical Technology Letters | Year: 2013

The effective dielectric constant of the top grounded coplanar waveguide with a liquid crystal (LC) superstrate for phase shifting applications is investigated in the frequency range of 30-60 GHz. Two nematic LC mixtures, namely E7 and MDA-00-3506, are used as the superstrate. The measurements show that MDA-00-3506 offers higher values of phase shift per millimeter than its E7 counterpart. In particular, the MDA-00-3506 provides 3.14°/mm, whereas E7 gives 2.79°/mm at 60 GHz. The results of the dielectric constants from measurement and computer modeling are found to agree to within 5%. For the modeling, a comprehensive finite element package predicting the local alignment of LC molecules and effective dielectric constant at different bias voltages and frequencies are used. Copyright © 2013 Wiley Periodicals, Inc. Source

Egan B.,University of Limerick | McCarthy M.A.,University of Limerick | Frizzell R.M.,University of Limerick | Frizzell R.M.,Bell Labs Ireland | And 3 more authors.
Composite Structures | Year: 2014

Three-dimensional explicit finite element modelling is used to predict the quasi-static bearing response of typical countersunk composite fuselage skin joints. In order to accurately simulate bearing failure, a user-defined 3D composite damage model was formulated for Abaqus/Explicit and included Puck failure criteria, a nonlinear shear law and a crack band model to mitigate mesh sensitivity. A novel approach was developed to employ characteristic element lengths which account for the orientation of composite ply cracks in the Abaqus/Explicit solver. Resulting models accurately predicted initial joint sticking behaviour and the elastic loading response of single-bolt and three-bolt joints, but preliminary predictions of bearing failure onset were overly-conservative. Improved failure predictions were obtained by utilising a fracture energy for compressive fibre failure which was considered more relevant for simulating bearing damage. The explicit models were exceptionally robust, showing capability to predict extensive hole crushing. Methods of dramatically improving joint model efficiency were highlighted. © 2013 Elsevier Ltd. Source

Bulja S.,Bell Labs Ireland | Grebennikov A.,Bell Labs Ireland
IEEE Transactions on Microwave Theory and Techniques | Year: 2012

In this paper, variable reflection-type attenuators based on varactor diodes are introduced and described in detail. Their main components are 3-dB couplers, varactor diodes, and lumped elements. © 2012 IEEE. Source

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