Search results for " key"
showing 10 items of 409 documents
A reappraisal of the Pleurotus eryngii complex – New species and taxonomic combinations based on the application of a polyphasic approach, and an ide…
2014
The Pleurotus eryngii species-complex comprises choice edible mushrooms growing on roots and lower stem residues of Apiaceae (umbellifers) plants. Material deriving from extensive sampling was studied by mating compatibility, morphological and ecological criteria, and through analysis of ITS1-5.8S-ITS2 and IGS1 rRNA sequences. Results revealed that P. eryngii sensu stricto forms a diverse and widely distributed aggregate composed of varieties elaeoselini, eryngii, ferulae, thapsiae, and tingitanus. Pleurotus eryngii subsp. tuoliensis comb. nov. is a phylogenetically sister group to the former growing only on various Ferula species in Asia. The existence of Pleurotus nebrodensis outside of S…
L'éducation aux valeurs à l'épreuve du socle commun
2010
Having examined values in education since earliest times on the one hand and the formal structuring of curricula throughout the XIXth century on the other hand, we will show how Jules Ferry's programmes are at the junction of two different approaches to moral education. Therefore, we will consider the main changes which structured the way it was taught throughout the XXth century. In France, the setting up of a base for common knowledge and common skills sheds a new light on social and civic skills, autonomy and initiative. These 6th and 7th pillars will compare favourably with other educational programmes, moral and religious, particularly in French-speaking Belgium as well as in Quebec. C…
New super-orthogonal space-time trellis codes using differential M-PSK for noncoherent mobile communication systems with two transmit antennas
2010
Published version of an article in the journal: Annals of Telecommunications-Annales Des Telecommunications. Also available from the publisher at: http://dx.doi.org/10.1007/s12243-010-0191-1 In this paper, we develop super-orthogonal space-time trellis codes (SOSTTCs) using differential binary phase-shift keying, quadriphase-shift keying and eight-phase shift keying for noncoherent communication systems with two transmit antennas without channel state information at the receiver. Based on a differential encoding scheme proposed by Tarokh and Jafarkhani, we propose a new decoding algorithm with reduced decoding complexity. To evaluate the performance of the SOSTTCs by way of computer simulat…
Stackelberg-Cournot and Cournot equilibria in a mixed markets exchange economy
2012
In this note, we compare two strategic general equilibrium concepts: the Stackelberg-Cournot equilibrium and the Cournot equilibrium. We thus consider a market exchange economy including atoms and a continuum of traders, who behave strategically. We show that, when the preferences of the small traders are represented by Cobb-Douglas utility functions and the atoms have the same utility functions and endowments, the Stackelberg-Cournot and the Cournot equilibrium equilibria coincide if and only if the followers’ best responses functions have a zero slope at the SCE.
A method to estimate the path gains and propagation delays of underwater acoustic channels using the arrival phase information of the multipath compo…
2017
Abstract We propose a method for the estimation of the channel parameters of underwater acoustic channels (UACs) by using a pseudo-noise (PN) sequence. For the channel sounding, the PN sequence is coherently modulated on a carrier frequency by using a binary phase-shift keying (BPSK) modulation scheme. For the demodulation, the arrival phases of the received BPSK signals must be known at the receiver. In practice, however, the arrival phases of the received signal are unknown. We propose to demodulate the received BPSK signal by using an hypothetical arrival phase, which will be increased from 0 to 2 π . The demodulated signal obtained by using the hypothetical arrival phase is then correla…
Encriptación óptica empleando llaves Weierstrass-Mandelbrot
2013
[EN] This paper presents the generation of encryption keys using the local oscillating properties of the partial sums of Weierstrass-Mandelbrot fractal function. In this way, the security key can be replicated if the parameters used to obtain it are known. Therefore, these parameters can be sent instead of sending the key. This procedure reduces the amount of information to be sent and prevents possible interception of the key. Moreover, the key can not be affected by data loss or pollution. The effectiveness of the Weierstrass-Mandelbrot keys were demonstrated by computer simulation in a 4f optical encryption system and the double random phase encoding technique. These keys allow us to enc…
Perfomance of Ultra-Wideband OFDM Systems Using Adaptive MPSK Modulation over Nakagami-m Channels
2006
The physical layer proposal of the Multiband OFDM (MB-OFDM) Alliance to the TG3a Working Group of IEEE802.15 for ultra wideband (UWB) systems defines the use of a fixed QPSK modulation scheme in all subcarriers corresponding to 14 subbands of this proposal. In this paper, an adaptive MPSK digital modulation scheme has been proposed to improve the average capacity expressed in bits/symbol for the MB-OFDM. The channel fading has been modeled Nakagami-m distributed and the power delay profile (PDP) is assumed exponential. This average capacity has been evaluated for many channel conditions as a function of the average signal-to-noise ratio (SNR) and the fading parameter of the Nakagami-m distr…
Robustness of 40 Gb/s ASK modulation formats in the practical system infrastructure.
2006
In this work, we analyzed by means of numerical and laboratory experiments the resilience of 40 Gb/s amplitude shift keying modulation formats to transmission impairments in standard single-mode fiber lines as well as to optical filtering introduced by the optical add/drop multiplexer cascade. Our study is a pre-requisite to assess the implementation of cost-effective 40 Gb/s modulation technology in next generation high bit-rate robust optical transport networks. © 2006 Optical Society of America.
An improvement of NFC-SEC with signed exchanges for an e-prescription-based application
2013
International audience; In the context of an aging population, drug intake can be a potential source of errors leading to death in some cases. Almost all of these errors are unintentional and come from incorrect prescriptions, unsuitable dosages for the patient or incompatibility with other treatments. To limit these risks which are especially important in the elderly or pre-dependency, we propose a secure system for drug treatment through the NFC (Near Field Communication) contact-less communication technology. The proposed system provides security mechanisms such as integrity, authentication, encryption and non-repudiation. To ensure this security, an extension of the international standa…
Performance evaluation of sum-of-cisoids Rice/Rayleigh fading channel simulators with respect to the bit error probability
2014
Sum-of-cisoids (SOC) processes provide an important framework for the modeling and simulation of multipath fading channels. In this paper, we analyze the performance of SOC Rice/Rayleigh narrowband fading channel simulators with respect to the bit error probability (BEP) of quadrature phase shift keying (QPSK) and differential phase shift keying (DPSK) systems with both coherent and noncoherent demodulation. For the BEP of coherent QPSK and DPSK, exact analytical expressions are derived, which provide insight into the influence of the number of propagation paths and the path gains on the system performance. It will be shown that at least 10 multipath components are required to guarantee tha…