École nationale supérieure de physique de Strasbourg

About: École nationale supérieure de physique de Strasbourg is a based out in . It is known for research contribution in the topics: Holography & Emissivity. The organization has 120 authors who have published 102 publications receiving 1609 citations.

A Design Oriented Charge-based Current Model for Symmetric DG MOSFET and its Correlation with the EKV Formalism

Abstract: We propose a design oriented charge-based model for undoped DG MOSFETs under symmetrical operation that aims at giving a comprehensive understanding of the device from the design strategy. In particular, we introduce useful normalizations for current and charges that in turn lead to very simple relationships among the physical quantities. Finally, we emphasize on the link that exists between this approach and the EKV formalism derived for bulk MOSFETs, which in turn leads to the unique gms/ID design methodology for DG architectures. © 2004 Elsevier Ltd. All rights reserved.

Nonequispaced curvelet transform for seismic data reconstruction: A sparsity-promoting approach

Abstract: We extend our earlier work on the nonequispaced fast discrete curvelet transform (NFDCT) and introduce a second generation of the transform. This new generation differs from the previous one by the approach taken to compute accurate curvelet coefficients from irregularly sampled data. The first generation relies on accurate Fourier coefficients obtained by an l2 -regularized inversion of the nonequispaced fast Fourier transform (FFT) whereas the second is based on a direct l1 -regularized inversion of the operator that links curvelet coefficients to irregular data. Also, by construction the second generation NFDCT is lossless unlike the first generation NFDCT. This property is particularly attractive for processing irregularly sampled seismic data in the curvelet domain and bringing them back to their irregular record-ing locations with high fidelity. Secondly, we combine the second generation NFDCT with the standard fast discrete curvelet transform (FDCT) to form a new curvelet-based method, coined noneq...

State estimation of stochastic singular linear systems

Abstract: This simple algorithm for the state estimation of stochastic singular linear systems is based on the least squares method.

Fuzzy hidden Markov chains segmentation for volume determination and quantitation in PET

Abstract: Accurate volume of interest (VOI) estimation in PET is crucial in different oncology applications such as response to therapy evaluation and radiotherapy treatment planning. The objective of our study was to evaluate the performance of the proposed algorithm for automatic lesion volume delineation; namely the fuzzy hidden Markov chains (FHMC), with that of current state of the art in clinical practice threshold based techniques. As the classical hidden Markov chain (HMC) algorithm, FHMC takes into account noise, voxel intensity and spatial correlation, in order to classify a voxel as background or functional VOI. However the novelty of the fuzzy model consists of the inclusion of an estimation of imprecision, which should subsequently lead to a better modelling of the 'fuzzy' nature of the object of interest boundaries in emission tomography data. The performance of the algorithms has been assessed on both simulated and acquired datasets of the IEC phantom, covering a large range of spherical lesion sizes (from 10 to 37 mm), contrast ratios (4:1 and 8:1) and image noise levels. Both lesion activity recovery and VOI determination tasks were assessed in reconstructed images using two different voxel sizes (8 mm3 and 64 mm3). In order to account for both the functional volume location and its size, the concept of % classification errors was introduced in the evaluation of volume segmentation using the simulated datasets. Results reveal that FHMC performs substantially better than the threshold based methodology for functional volume determination or activity concentration recovery considering a contrast ratio of 4:1 and lesion sizes of <28 mm. Furthermore differences between classification and volume estimation errors evaluated were smaller for the segmented volumes provided by the FHMC algorithm. Finally, the performance of the automatic algorithms was less susceptible to image noise levels in comparison to the threshold based techniques. The analysis of both simulated and acquired datasets led to similar results and conclusions as far as the performance of segmentation algorithms under evaluation is concerned.

Near-barrier fusion of S 32 + Zr 90 , 96 : The effect of multi-neutron transfers in sub-barrier fusion reactions

Abstract: Fusion excitation functions have been measured for the first time with rather good accuracy for $^{32}\mathrm{S}+^{90}\mathrm{Zr}$ and $^{32}\mathrm{S}+^{96}\mathrm{Zr}$ near and below the Coulomb barrier. The sub-barrier cross sections for $^{32}\mathrm{S}+^{96}\mathrm{Zr}$ are much larger than for $^{32}\mathrm{S}+^{90}\mathrm{Zr}$. A coupled-channels calculation considering the inelastic excitations is capable of describing sub-barrier enhancement only for $^{32}\mathrm{S}+^{90}\mathrm{Zr}$. The unexplained part for $^{32}\mathrm{S}+^{96}\mathrm{Zr}$ is found to be correlated with the positive-$Q$-value intermediate neutron transfers in this system. The comparison with $^{40}\mathrm{Ca}+^{96}\mathrm{Zr}$ suggests that couplings to the positive-$Q$-value neutron transfer channels may play a role in the sub-barrier fusion enhancement. Multi-neutron transfers are taken into account in Zagrebaev's semiclassical model to explain the discrepancies of the sub-barrier fusion cross sections for $^{32}\mathrm{S}+^{96}\mathrm{Zr}$.