Conservatoire national des arts et métiers

About: Conservatoire national des arts et métiers is a education organization based out in Paris, France. It is known for research contribution in the topics: Population & Context (language use). The organization has 3573 authors who have published 7127 publications receiving 141430 citations. The organization is also known as: CNAM & Conservatoire des arts et métiers.

The alamouti scheme with CDMA-OFDM/OQAM

Abstract: This paper deals with the combination of OFDM/OQAM with the Alamouti scheme. After a brief presentation of the OFDM/OQAM modulation scheme, we introduce the fact that the well-known Alamouti decoding scheme cannot be simply applied to this modulation. Indeed, the Alamouti coding scheme requires a complex orthogonality property; whereas OFDM/OQAM only provides real orthogonality. However, as we have recently shown, under some conditions, a transmission scheme combining CDMA and OFDM/OQAM can satisfy the complex orthogonality condition. Adding a CDMA component can thus be seen as a solution to apply the Alamouti scheme in combination with OFDM/OQAM. However, our analysis shows that the CDMA-OFDM/OQAM combination has to be built taking into account particular features of the transmission channel. Our simulation results illustrate the 2 × 1 Alamouti coding scheme for which CDMA-OFDM/OQAM and CP-OFDM are compared in two different scenarios: (i) CDMA is performed in the frequency domain, (ii) CDMA is performed in time domain.

On the control through leadership of the Hegselmann–Krause opinion formation model

Abstract: This paper deals with control strategies for the Hegselmann–Krause opinion formation model with leadership. In this system, the control mechanism is included in the leader dynamics and the feedback control functions are determined via a stabilization procedure and with a model predictive optimal control process. Correspondingly, the issues of global stabilization, controllability, and tracking are investigated. The model predictive control scheme requires to solve a sequence of open-loop optimality systems discretized by an appropriate Runge–Kutta scheme and solved by a nonlinear conjugate gradient method. Results of numerical experiments demonstrate the validity of the proposed control strategies and their ability to drive the system to attain consensus.

Robust nonlinear control associating robust feedback linearization and H/sub /spl infin// control

Abstract: In this note, a robust nonlinear controller for a nonlinear system subject to model uncertainties is proposed Such a controller associates a "robust feedback linearization" with a robust linear H/sub /spl infin// controller The robust feedback linearization exactly transforms the nonlinear system into a linear system equal to the linear approximation of the original nonlinear system around a nominal operating point The robustness of the resulting overall nonlinear controller is proved by theoretical arguments and illustrated through an application example, the control of a magnetic bearing system

Neurosteroids: Cerebrospinal fluid levels for Alzheimer's disease and vascular dementia diagnostics.

Abstract: A neurodegenerative disease such as Alzheimer’s disease (AD) is associated with significantly higher dehydroepiandrosterone (DHEA) levels in cerebrospinal fluid (CSF). Because the human brain is known to transform DHEA into DHEA sulfate (DHEAS), 7α-hydroxy-DHEA, 7β-hydroxy-DHEA, and 16α-hydroxy-DHEA, it is possible that DHEA accumulation in the brain results from a decreased production of such metabolites. To test this hypothesis, we have measured and compared CSF levels of DHEA, DHEAS, 7α-hydroxy-DHEA, 7β-hydroxy-DHEA, and 16α-hydroxy-DHEA in 14 patients with AD, 12 controls, and eight patients with another common dementia, vascular dementia (VD). Results indicated that DHEAS CSF levels were significantly decreased in AD and VD (P < 0.007), whereas other metabolite levels were not significantly changed. Use of steroid level ratios, such as DHEA/(7α-hydroxy-DHEA + 7β-hydroxy-DHEA), 7β-hydroxy-DHEA/DHEA, and DHEAS/DHEA ratios, resulted in significant differences between diseased and control patients (P < 0...