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Pirngruber G.D.,French Institute of Petroleum | Guillou F.,French Institute of Petroleum | Gomez A.,French Institute of Petroleum | Clausse M.,IRSTEA | Clausse M.,School of Engineering in Information and Communication Science and Technology
International Journal of Greenhouse Gas Control | Year: 2013

CO2 capture processes based on dry solid sorbents have been praised as a very attractive alternative to absorption by amine solvents (in particular monoethanolamine) in terms of energy consumption. The present paper critically analyzes these very optimistic predictions. It presents a theoretical analysis of three different temperature swing adsorption (TSA) processes: (i) a fixed bed, (ii) an isothermal fluidized bed and (iii) an adiabatic fluidized bed. The solid sorbent is supposed to be an amine immobilized on a support material. A high-level estimation of the energy consumption of the three processes shows that the fixed bed process would be by far the most interesting option, because the thermodynamic driving force for adsorption is higher in the fixed bed. The performances of both the fixed and fluidized bed process dramatically improve if the adsorption step is operated under close to isothermal conditions. Heat transfer in a fixed bed is much slower than in a fluidized bed. Providing the heat exchange area required for isothermal operation is challenging in the fixed bed, but not impossible according to our rough estimations. The paper also defines the adsorption properties (adsorption constant, adsorption capacity, heat of adsorption) of the optimal solid sorbent. © 2013 Elsevier Ltd. Source

Ben Gaid M.E.M.,French Institute of Petroleum | Cela A.,School of Engineering in Information and Communication Science and Technology
Automatica | Year: 2010

In many situations, control applications have to exchange information through limited bandwidth communication channels, which affect their behavior. For that reason, there is a strong need for methods that maximize the relevancy of the exchanged control signals. In general, increasing control signals' update frequency improves the disturbance rejection abilities whereas increasing their quantization precision improves the steady state performance. However, when the bandwidth is limited, increasing the update frequency necessitates the reduction of the quantization precision and vice versa. Motivated by these observations, and focusing on the uplink bandwidth limitations, an approach for the dynamical online state feedback assignment of control inputs' quantization precision and update rate is proposed. This approach, which is based on the model predictive control technique, enables us to choose the update rate and the quantization levels of control signals from a predefined set, in order to optimize the control performance. Practical stability properties of the approach are then studied. Finally, the effectiveness of the proposed method is illustrated on a simulation example. © 2010 Elsevier Ltd. All rights reserved. Source

Chen K.,School of Engineering in Information and Communication Science and Technology | Chan H.P.,City University of Hong Kong
International Journal of Photoenergy | Year: 2012

Silicon oxynitride (SiO xN y, SiON) optical waveguide ring resonator, in which a two-mode interferometer is used to replace the directional coupler in a conventional ring resonator, has been designed and fabricated. Preliminary results exhibit the same of free spectral range of 100GHz but different quality factors of 3700 and 3900 at 1550nm for transverse electric (TE) and transverse magnetic (TM) mode, respectively. The extinction ratio is more than 18dB over the entire C-band, and the insertion loss is lower than 9.5dB for TE and TM mode. Copyright © 2012 Kaixin Chen and Hau Ping Chan. Source

Li X.-G.,Northeastern University China | Niculescu S.-I.,CNRS Laboratory of Signals & Systems | Cela A.,School of Engineering in Information and Communication Science and Technology | Wang H.-H.,Northeastern University China | Cai T.-Y.,Northeastern University China
IEEE Transactions on Automatic Control | Year: 2013

Obtaining the Puiseux series of multiple imaginary (characteristic) roots (MIRs) is a fundamental issue in the stability analysis of timedelay systems. However, to the best of the authors' knowledge, this issue has not been fully investigated up to date. This note focuses on the Puiseux series expansion of MIRs of linear time-invariant systems including commensurate delays. For anMIR of anymultiplicity, we propose an algorithm for defining the structure of the Puiseux series, as well as the explicit computation of the corresponding coefficients. By using the proposed method, we can find all the Puiseux series corresponding to all the root loci. © 2012 IEEE. Source

Sabry Y.M.,School of Engineering in Information and Communication Science and Technology | Sabry Y.M.,Si-Ware Systems | Saadany B.,Si-Ware Systems | Khalil D.,Si-Ware Systems | And 3 more authors.
Light: Science and Applications | Year: 2013

Miniaturized optical benches process free-space light propagating in-plane with respect to the substrate and have a large variety of applications, including the coupling of light through an optical fiber. High coupling efficiency is usually obtained using assembled micro-optical parts, which considerably increase the system cost and integration effort. In this work, we report a high coupling efficiency, monolithically integrated silicon micromirror with controlled three-dimensional (3D) curvature that is capable of manipulating optical beams propagating in the plane of the silicon substrate. Based on our theoretical modeling, a spherical micromirror with a microscale radius of curvature as small as twice the Gaussian beam Rayleigh range provides a 100% coupling efficiency over a relatively long optical path range. Introducing dimensionless parameters facilitates the elucidation of the role of key design parameters, including the mirror's radii of curvature, independent of the wavelength. A micromachining method is presented for fabricating the 3D micromirror using fluorinated gas plasmas. The measured coupling efficiency was greater than 50% over a 200-μm optical path, compared to less than 10% afforded by a conventional flat micromirror, which was in good agreement with the model. Using the 3D micromirror, an optical cavity was formed with a round-trip diffraction loss of less than 0.4%, resulting in one order of magnitude enhancement in the measured quality factor. A nearly 100% coupling was also estimated when matching the sagittal and tangential radii of curvature of the presented micromirror's surface. The reported class of 3D micromirrors may be an advantageous replacement for the optical lenses usually assembled in silicon photonics and optical benches by transforming them into real 3D monolithic systems while achieving wideband high coupling efficiency over submillimeter distances. © 2013 CIOMP. All rights reserved. Source

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