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Cefalo M.,Polytechnic University of Catalonia | Mirats Tur J.M.,CetAqua
International Journal of Solids and Structures | Year: 2010

This work addresses the problem of real-time self-collision detection for a movable tensegrity structure. We show that it can be tackled as the collision detection between two generic cylinders moving in R3. It is a simplified version of the more general problem of dynamic collision detection between two general shaped rigid bodies in the space. Two algorithms are proposed. The first presented approach is based on the exact value of the distance between two cylinders, the second is based on a new theorem which allows to estimate the exact distance for a given maximum desired error. In some circumstances, the second approach can be preferred because faster. © 2010 Elsevier Ltd. All rights reserved.

Cefalo M.,Institute Of Robtica I Informtica Industrial | Mirats-Tur J.M.,CetAqua
International Journal of Solids and Structures | Year: 2011

In this paper we propose a new dynamic model, based on quaternions, for tensegrity systems of class-1. Quaternions are used to represent orientations of a rigid body in the 3-dimensional space eliminating the problem of singularities. Moreover, the equations based on quaternions allow to perform more precise calculations and simulations because they do not use trigonometric functions for the representation of angles. We present a thorough introduction of tensegrities and the current state of research. We also introduce the quaternions and provide in the appendix some important details and useful properties. Applying the Euler-Lagrange approach we derive a comprehensive dynamic model, first for a simple rigid bar in the space and, at last, for a class-1 tensegrity system. We present two model forms: a matrix and a vectorial form. The first more compact and easier to write, the latter more suitable to apply the tools and the theory based on vector fields. © 2010 Elsevier Ltd. All rights reserved.

Casas S.,Polytechnic University of Catalonia | Bonet N.,Polytechnic University of Catalonia | Aladjem C.,Solvay Group | Cortina J.L.,Polytechnic University of Catalonia | And 2 more authors.
Solvent Extraction and Ion Exchange | Year: 2011

Electrodialysis (ED) was studied as a technology to concentrate NaCl from SWRO reject in order to be reused in the chlor-alkali industry. A mathematical model was developed based on Nernst-Planck equations to predict the performance of the Barcelona ED pilot plant. Several of the model parameters were obtained experimentally and others were taken from the literature. The model was able to accurately predict the NaCl concentration reached, the time required to reach maximum concentration, and production overflow as a function of the operation conditions. in this article, the mathematical model is fully described and validated with preliminary experimental results obtained. © Taylor & Francis Group, LLC.

Reig M.,Polytechnic University of Catalonia | Casas S.,CetAqua | Valderrama C.,Polytechnic University of Catalonia | Gibert O.,Polytechnic University of Catalonia | Cortina J.L.,Polytechnic University of Catalonia
Desalination | Year: 2016

Water scarcity in the Mediterranean basin has been solved by using seawater desalination reverse osmosis technology (SWD-RO). This technology produces brine which is discharged back into the sea resulting in an environmental impact on marine ecosystems. Under the circular economy approach, the aim of this work is to recover resources from NaCl-rich brine (˜ 60–70 g/L), e.g. in the form of NaOH and HCl, by integration of two ion exchange-based membrane technologies and quantify the electrical energy consumption. Electrodialysis (ED) incorporating monovalent selective cation exchange membranes as divalent ions purification and concentration of the NaCl present in the SWD-RO brine, was integrated with bipolar membrane ED (EDBM) to produce NaOH and HCl. Current densities of 0.30–0.40 kA/m2 at two temperature ranges simulating different seawater temperature regimes (15–18 °C and 22–28 °C) were tested and a pure NaCl solution was used as starting concentrate stream. NaCl-rich brines with 100 or 200 g NaCl/L were obtained by ED and then introduced in the EDBM stack producing HCl and NaOH up to 2 M, depending on the initial concentrations. A minimum energy consumption of 1.7 kWh/kg NaOH was calculated when working by EDBM with initial concentrations of 104 g NaCl/L and 0.24 M HCl and NaOH. © 2016 Elsevier B.V.

Casas S.,Polytechnic University of Catalonia | Aladjem C.,Solvay Group | Cortina J.L.,Polytechnic University of Catalonia | Larrotcha E.,CetAqua | Cremades L.V.,Polytechnic University of Catalonia
Solvent Extraction and Ion Exchange | Year: 2012

Seawater RO brines have been identified as an alternative to common NaCl sources for the chlor-alkali industry. Electrodialysis (ED) has been evaluated as a preliminary step of NaCl concentration for these brines. Experimental results showed that ED was an effective concentration technology, where values up to 252 gNaCl L-1 were reached at 0.3-0.4 kA m -2 with a power consumption of approx. 0.20-0.30 kWh kg-1 NaCl. As the membranes used (Neosepta CIMS and ACS) were mainly selective for univalent ions, polyvalent ions were partially removed from the brine, benefiting its reuse. NaCl concentrated solutions are to be used as feed brine in the chlor-alkali industry after a purification step. © 2012 Copyright Taylor and Francis Group, LLC.

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