Rate adaptive resource allocation for OFDM downlink transmission

In this paper, we present a multiuser rate adaptive resource allocation for OFDM downlink transmission. This new algorithm assign one bit at a time to user that has the minimum total power in the subcarrier that requires the least additional power. Simulation results show that the proposed algorithm achieves a higher capacity than previous existing algorithms and distributed the overall capacity more fairly among users.     

Surface properties of petroleum oil polar fraction as investigated by Zetametry and DRIFT spectroscopy

The polar fractions of various transformer petroleum oils (one new and two used oils) were extracted from the neat oils using silica as solid support. We found that the amount of the polar fraction adsorbed on the silica was higher for the used oils as compared to the new one. Such oil polar fractions are insoluble in low molecular weight paraffins (n-hexane and n-heptane) and are soluble in ethanol. The analysis of the diffuse reflectance infrared Fourier transform (DRIFT) spectra of the silica samples coated with oil polar components indicate the presence of oil polar functional groups such as hydroxyl, aromatic and carboxyl groups resembling asphaltenes or resins. In addition, we studied the electrical properties of the oil polar fraction by determining the ζ potential, in water, of the coated silica. In order to compare the modified and the non-modified silica surface properties, we made blank experiments by measuring the surface charge in water of the bare SiO₂ particles. The negative surface charge at the water/oil–silica interface was found to increase with pH, resulting from the increase in ionisation of the oil polar fraction acidic surface groups. The objective of varying the pH was to analyse the possible acid–base interactions at the water–oil interface for substrates having various oil polar fraction contents. The polar components in the neat oil adsorb on the silica surface and increase its surface charge and stabilisation in water. We found a good correlation between the amounts of the oil polar fractions, the surface concentration of their functional groups (carboxylic and phenolic groups) and the magnitude of their ζ potential at the water/oil–silica interface.     

Reactivity monitoring in ADS, application to the MYRRHA ADS project

Monitoring of reactivity in an ADS should be performed on-line with a simple, accurate and robust technique. Within the range of experimental reactor techniques, no single technique can be selected which meet these requirements. Therefore a combination of different techniques has to be chosen in a way that various off-line techniques serve as a calibration method for the on-line measurement technique. As an on-line measurement technique, the current-to-flux reactivity indicator is the most simple and robust solution. The current-to-flux reactivity indicator is based on the fact that in a sub-critical multiplying medium with a driving source the flux level is proportional to the driving source intensity, hence the beam current, and the reactivity level. However, since the proportionality constant depends on a number of core-dependent parameters and detector characteristics, this current-to-flux indicator has to be calibrated on a regular basis. For this calibration, one could benefit from the occurrence of accelerator beam trips to determine the reactivity level in dollars by means of a prompt jump analysis of the flux level change. Hence, the prompt jump reactivity indicator could act as a first calibration tool of the current-to-flux indicator. Since the prompt jump indicator still relies on the value for the effective delayed neutron fraction to determine reactivity level, complementary techniques have to be used to obtain a more accurate determination of the reactivity. Techniques based on reactor noise methods such as the RAPJA-technique which is a combination of the Rossi-Alpha method and a Prompt Jump Analysis can be used in this respect. In the future the bi-spectral ratio from the Cf-source driven noise analysis could be used for this purpose.     

Subcarrier and Power Allocation for the Downlink of Multiuser OFDM Transmission

In this paper, a new algorithm for subcarrier and power allocation for the downlink of multiuser OFDM transmission is presented. The proposed algorithm is more stable and it offers a lower complexity and better performance than previous existing algorithms. Khalid El Baamrani was born in Ouarzazate, Morocco in 1976. He received the License degree (equiv. B.A.) in electronic engineering from the University of Cadi Ayyad, Marrakech, Morocco, in 1998, the D.E.S.A. (equiv. M.A) in electrical engineering from the University of CadiAyyad, Marrakech, Morocco, in 2000, the certificate in engineering of the data-processing networks and telecommunications from the national institute of posts and telecommunications, Rabat, Morocco in 2002 and the Ph.D. degree at University of Cadi Ayyad, Marrakech, Morocco in 2005. His research interests include multicarrier modulation, communication theory, multiuser information theory, OFDM and DSL systems. Victor P. Gil Jiménez received the B. Eng. in Telecommunications with honors from University of Alcalá in 1998 and the M. Eng. in Telecommunications and the PhD. degree both from the University Carlos III de Madrid in 2001 and 2005, respectively. He is with the Department of Signal Theory and Communications at the University Carlos III de Madrid as an Assistant Professor. He worked at the Spanish Antarctica Base in 1999 as Communications Staff. He visited University of Leeds and Chalmers Technical University in 2003 and 2004 respectively. His research interests include multicarrier communications and signal processing for wireless systems. Ana Garcia Armada received the Telecommunication Engineer degree and the Ph.D in Electrical Engineering both from the Polytechnic University of Madrid (Spain) in 1994 and 1998, respectively. She is currently working as an Associate Professor at the University Carlos III de Madrid, where she has occupied several management positions. She has participated in several national and international research projects, most of them related to OFDM. She is coauthor of four books on wireless communications and signal processing. She has published 13 papers in international journals and more than 40 papers in conferences. She has contributed to international organizations such as ITU and ETSI. She has performed research stays in ESA-ESTEC, Kansas University, Stanford University and Bell Labs. Her research interests are simulation of communication systems, multicarrier and MIMO techniques.     

Electrodeposition of nanostructured cuprous oxide on various substrates and their electrochemical and photoelectrochemical properties

Journal of Materials Science: Materials in Electronics - Nanostructured Cu2O films have been developed on various conductive substrates (FTO, ITO, and Mo) by a low-cost electrodeposition process...     

Static output‐feedback for Takagi–Sugeno systems with delays

A practical methodology to design controllers for Takagi–Sugeno discrete‐time systems with unknown delays is proposed, based on using Linear Matrix Inequalities. More precisely, the design of discrete‐time output‐feedback stabilizing controllers in the presence of bounded delays is solved, when values of the disturbance attenuation and decay‐rate are imposed. A numerical example is provided to illustrate the proposed approach. Copyright © 2010 John Wiley & Sons, Ltd.     

Evaluation of the energy parameter J on rubber-like materials: Comparison between experimental and numerical results

The general purpose of our study is the determination of the energy parameter J when dealing with fracture of rubber-like materials. The energy parameter J is expressed in a multiplicative form in which a calibration factor is introduced in order to take into account the finite dimensions of the specimen. The parameter J, issued from fracture tests performed on S.E.N.T specimen of an E.P.D.M rubber is compared with the the J integral which is computed using a finite element procedure for the non-linear elastic materials with large deformation. The numerical results are in good agreement with the experimental data when considering the deeply cracked specimen (a/w ≥ 0.5). Below this limit, a divergence is pointed out which is attributed to a lack of accuracy of the identification procedure used to determine the experimental calibration factor. When this one is determined using the numerical J integral results, a better concordance is obtained.     

Polling Best Effort Traffic in Bluetooth

Bluetooth [1] is a wireless access technology where polling is used to sharebandwidth among the nodes. We have introduced a new poller named PredictiveFair Poller (PFP) in [2, 3]. In this paper we explain the operation of thePredictive Fair Poller and compare it with the conventional Round Robin pollerand the Fair Exhaustive Poller (FEP) [4] for two Best Effort trafficscenarios. We show through simulations that the Predictive Fair Poller is ableto divide bandwidth in a fair and efficient manner.