Robust output feedback stabilization of uncertain time-varying state-delayed systems with saturating actuators

The robust output feedback stabilization problem for state-delayed systems with time-varying delays and saturating actuators is addressed here. The systems considered are continuous-time, with parametric uncertainties entering all the matrices in the system representation. A saturating control law is designed and a region of initial conditions is specified within which local asymptotic stability of the closed-loop system is ensured. The least conservative approach that employs the Lyapunov–Krasovskii functional is adopted to ensure stabilization. The designed controller is dependent on the time-delay and its rate of change. The controller is constructed in terms of the solution to a set of matrix inequalities.     

Large Bolometer Arrays with Superconducting NbSi Sensors for Future Space Experiments

New techniques in microelectronics allow to build large arrays of bolometers filling the focal plane of submillimeter and millimeter telescopes. The expected sensitivity increase is the key for the next generation of space experiments in this wavelength range. Superconducting bolometers offer currently the best prospects in terms of sensitivity and multiplexed readout. We present here the developments led in France based on NbSi alloy thermometers. The manufacturing process of a 23 pixel array and the test setup are described.      

Elastic and thermodynamic properties of OsSi, OsSi2 and Os2Si3

All components of the elasticity tensors for OsSi (P2₁3), OsSi₂ (Cmca) and Os₂Si₃ (Pbcn and P-4c2) were computed by means of the stress–strain method in the framework of the density functional theory. The total energies and stress were calculated using density functional theory within the local density and conjugate gradient approximations. From the knowledge of the elastic constants, the Born stability criteria were discussed and the Debye approximation was used to evaluate the enthalpies of formation (ΔH_f) of the different compounds. The ΔH_f calculated at 298 K for OsSi is in correct agreement with the experimental data but for Os₂Si₃(Pbcn) ΔH_f is 30 kJ/mol of atoms more exothermic than the measured one. Moreover, we have found that from 1200 K the P-4c2 phase of Os₂Si₃ is most stable from the energy point of view than the Pbcn structure.     

Impact of silicon nitride CESL on NLDEMOS transistor reliability

Aging of the linear drain current during OFF stress on a N-type lateral drain extended MOS is shown to be induced by the amorphous silicon nitride Contact Etch Stop Layer (CESL). A design of experiment on its PECVD conditions enables to demonstrate that the higher its Si-rich composition or at least of its interface, the higher the degradation. Supported by TCAD simulations, we propose a charge displacement model in the CESL that leads to the depletion of the extended drain region during stress explaining the on-resistance increase monitored by the linear drain current.     

Failure of a Fusion Welded Ball Joint as a Result of Modification in MnS Direction

A failure investigation was performed on a ball joint from an ATV front suspension system. The location of the fracture was the bearing ball/stud interface, which is a fusion-welded joint, and occurred after approximately 20 h of field-testing. The two parts are made out of carbon steel and were previously heat-treated. Many elongated MnS inclusions were found in the stud material, and these inclusions were parallel to the symmetry axis. Even though these inclusions were not significantly sized, their number was important. Macroscopic evidence showed that the joint failed in a ductile mode under centered tensile overload. Microscopic examination showed that MnS orientation changed in the fusion joint area. The inclusions had been redirected during the welding process and laid parallel to the fracture surface. This reorientation caused a significant decrease in the effective cross section of the joint and overload fracture occurred.