A Time-Frequency Well-localized Pulse for Multiple Carrier Transmission

In multicarrier transmission schemes, the essential requirement on the elementary pulse or envelope function is the orthogonality with its time-frequency shifted versions. However, the time and frequency dispersion of the mobile radio channel leads to the loss of orthogonality which produces intersymbol interference (ISI) and interchannel interference (ICI). Therefore, another requirement on the elementary pulse has to be imposed: the good localization in time and frequency. Based on the characteristics of the mobile radio channel, we design a new pulse to minimize ICI and ISI.     

Image registration in electron microscopy: Application of a robust method

The geometric registration of two electron microscopic images generally is performed by maximizing the cross-correlation coefficient between them. We show that a new similarity measure (the number of sign changes) is useful for performing simultaneously geometric and gray-level registration. This method is robust, which means that it provides a good estimation of the parameters even in the presence of outliers that cannot be described by the registration model.     

Finite element and reliability: a method for compound variables—application on a cracked heating system

Nuclear engineering systems are designed to ensure safety criteria. To predict the behavior of mechanical systems, the finite element analysis (FEA) is actually the main tool for numerical analysis of mechanical problems. In order to design a system under data variability considerations, performance functions have to be defined by the relationship between the action effects and the material strengths. Then a certain level of safety should be satisfied with sufficiently high probability. This is the subject of the reliability theory. Controlling a FEA software in order to carry out the reliability analysis, it is to define a ‘combination method’. This paper proposes a general method for the reliability analysis combined with FEA codes. The method is efficient for independent, correlated and compound random variables. The proposed method is illustrated by numerical example of a cracked membrane exposed to thermal shortening. The risk to evaluate is represented by the crack propagation in the material.     

Pyromètre à fibre optique pour la mesure des basses températures

Optical fibres made of fluoride glass allow surface temperature measurement of various objects uneasy to reach, mobile or located in adverse environments. Such an infrared fibre, with transmittance extending beyond 5 μm, allows transmission ofIr radiation to anIr sensor which transforms it into a usable signal. The set-up realised can take measurements down to 50 °C, and 30 °C in a next future. The sensor signal is pre-amplified and then processed by a lock-in amplifier. AnIr reference internal source is used to deliver a known constant level to the sensor and allows absolute temperature measurements. The present measurement accuracy obtained with a blackbody at 200 °C is ± 0.5 °C. We are about to use such a device for monitoring irradiated fuel rods temperature in the Superphenix 1 breeder power plant.