Sur les méthodes de calcul de l’exposant linéique de propagation et d’impédance caractéristique des câbles aériens et enterrés

The propagation constant of a line or a cable, and its characteristic impedance represent two parameters which are needed in order to calculate the variation as a function of the time of a current induced by an emp.For the aerial lines expressions which take into account the presence of the soil could be developed but the case of the buried conductors is of a more difficult approach. The aim of this study is to present solutions introduced by different authors and to compare them with a calculation method for the propagation constant using iterations, proposed by the authors. If this value is known it is shown that the characteristic impedance calculation of buried cables can be improved by avoiding the necessity to compute with a reasonable precision the impedance of the ground.     

Input-to-state stability analysis for interconnected difference equations with delay

Input-to-state stability (ISS) of interconnected systems with each subsystem described by a difference equation subject to an external disturbance is considered. Furthermore, special attention is given to time delay, which gives rise to two relevant problems: (i) ISS of interconnected systems with interconnection delays, which arise in the paths connecting the subsystems, and (ii) ISS of interconnected systems with local delays, which arise in the dynamics of the subsystems. The fact that a difference equation with delay is equivalent to an interconnected system without delay is the crux of the proposed framework. Based on this fact and small-gain arguments, it is demonstrated that interconnection delays do not affect the stability of an interconnected system if a delay-independent small-gain condition holds. Furthermore, also using small-gain arguments, ISS for interconnected systems with local delays is established via the Razumikhin method as well as the Krasovskii approach. A combination of the results for interconnected systems with interconnection delays and local delays, respectively, provides a framework for ISS analysis of general interconnected systems with delay. Thus, a scalable ISS analysis method is obtained for large-scale interconnections of difference equations with delay.     

Emotion-Induced Retrograde Amnesia and Trait Anxiety.

Emotional arousal can both enhance and impair memory. Considering that both emotional memory and trait anxiety (TA) have been associated with adrenergic activity, the authors investigated whether there is an association between 2 opposite emotional memory biases and the TA. The authors used a procedure recently put forward by B. A. Strange, R. Hurlemann, and R. J. Dolan (2003) to elicit an emotion-induced retrograde amnesia (ERA) coupled to an emotional memory enhancement (EME). The authors contrasted the association between these emotional memory biases and the TA in several conditions involving different levels of encoding and types of recall. The results presented here indicated a significant interaction of the TA with EME and ERA and the dependency of these biases on the consciously controlled use of memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Monitoring TRPC7 Conformational Changes by BRET Following GPCR Activation

Transient receptor potential canonical (TRPC) channels are membrane proteins involved in regulating Ca²⁺ homeostasis, and whose functions are modulated by G protein-coupled receptors (GPCR). In this study, we developed bioluminescent resonance energy transfer (BRET) biosensors to better study channel conformational changes following receptor activation. For this study, two intramolecular biosensors, GFP10-TRPC7-RLucII and RLucII-TRPC7-GFP10, were constructed and were assessed following the activation of various GPCRs. We first transiently expressed receptors and the biosensors in HEK293 cells, and BRET levels were measured following agonist stimulation of GPCRs. The activation of GPCRs that engage Gα_q led to a Gα_q-dependent BRET response of the functional TRPC7 biosensor. Focusing on the Angiotensin II type-1 receptor (AT₁R), GFP10-TRPC7-RLucII was tested in rat neonatal cardiac fibroblasts, expressing endogenous AT₁R and TRPC7. We detected similar BRET responses in these cells, thus validating the use of the biosensor in physiological conditions. Taken together, our results suggest that activation of Gα_q-coupled receptors induce conformational changes in a novel and functional TRPC7 BRET biosensor.     

Two-step curing processes for coating application

Two novel two-stage cure processes will be described, both involving oxetane chemistry. In both processes, the two consecutive cure processes are completely separated from one another.     

Coupled-field FEM nonlinear dynamics analysis of continuous microsystems by non-incremental approach

This paper deals with numerical prediction of the nonlinear dynamic behaviour of electromechanical continuous microsystems, in presence of large displacements. Finite Element Method (FEM) is applied, by following so-called “sequential” approach, based on the solution in series of coupled electromechanical problem. In spite of tested approaches available in the literature, a “non-incremental” method is developed to enhance the performances of numerical tools. In practice, for microelectrostatic beam actuators, the total voltage may be applied once, in only one step, instead of by small increments. Non-incremental approach is based on two features. A special non-incremental beam element is introduced to deal with so-called geometrical nonlinearity of microbeam, caused by large displacement. It allows computing the total displacement of a cantilever microbeam, by integrating local rotation and axial deformation of cross-section, by avoiding to refer to the assumption of small displacement. Proposed procedure includes a preliminary static nonlinear analysis, to find the equilibrium condition, then a computation of nodal voltages for the deformed shape and of electric load. Equations of motion are integrated in time, by Newmark's method, while at each step, Newton-Raphson approach finds the instantaneous equilibrium, by applying the total voltage, instead of a small incremental value. Results evidenced a fast convergence even for large initial deflection. Moreover, typical peculiarities of nonlinear dynamic system, like softening effect in frequency response and amplitude jumping are observed. The whole proposed approach is currently under experimental validation and improvement to include damping effects, to study the dynamic stability of the microsystem. Eugenio Brusa was born in Turin (Italy) on February 8th, 1969. Graduated aeronautical engineer (1993) and Ph.D. in Design and construction of machines (1997) at Politecnico di Torino (Technical University of Turin). Assistant professor at Politecnico di Torino, Dept. Mechanics, and head of the Spin Test Laboratory from 1998 to 2001, then at Università degli Studi di Udine (2001–2002). On 2002 he appointed Associate professor at Università degli Studi di Udine, chair of Machine Design. Since 2005 is Coordinator of the teaching staff of the Master on Project Management and System Engineering of the University of Udine. Research activity: Design of mechanical structures, rotors and structural mechatronic systems, for space applications (Italian Space Agency, INTAS), cold rolling mills (SKF), active magnetic suspension (ESA subcontract), motorvehicle dynamics (FIAT group) and MEMS. Teaching activity in international courses: TU Delft (2001), TU Helsinki (2003), Int. Centre for Mechanical Sciences CISM (2004), Italy, Université Blaise Pascal, Clermont Ferrand (2005), France. More than 80 scientific publications. Mircea Gh. Munteanu was born in Brasov (Romania), on April 5th, 1946. Graduated Mechanical Engineer (1968) and PhD in Applied Mechanics at Transilvania University of Brasov, Romania. Since 1979 in staff at Stress Analysis and Mechanical Vibrations Dept., Transilvania University of Brasov. Since 1993 full professor of Stress Analysis and Mechanical Vibrations, Transilvania University of Brasov. Invited professor at Università degli Studi di Udine, Italia, in the framework of a grant on microsystem mechanical design. Research activity on static and dynamic FEM analysis of mechanical structures, multi-body systems, precision engineering, microsystem design. More than 100 publications on national and international journals and congresses, several books.     

Biased micromechanical cantilever arrays as optical image memory

We show that an array of optically actuated biased cantilevers can work as an optical data storage, able to encode data stored as arrays of optical pixels (images). Each of these optical pixels can, in addition, have a predetermined pixel depth, expressed as a certain number of gray levels. This new optical memory is able to work at a data rate of approximately 7 GB/s for an image with 128 x 128 pixels.     

Oxidation of GaAs in an oxygen multipole plasma

In a multiple plasma source (which has a hot cathode associated with a magnetic confinement) homogeneous plasmas of satisfactory density ((5–10) × 10¹⁰ cm^-3) can be obtained in large volumes. This source appears to be very convenient for the study of plasma oxidation and has been applied to the case of GaAs.Homogeneous oxides covering a few square centimetres have been obtained with typical growth rates of 200–250 Å min^-1. The electrical properties of metal- oxide-semiconductor structures are controlled by interface states in the whole band gap: in the upper half (near the middle of the gap) densities in the range 10¹³ cm^-2 eV^-1 of rather “slow” interface states (which are unable to follow a 1 MHz signal at room temperature) and in the lower half “faster” interface states are detected from C(V) measurements on n-type and p-type samples.However these interface states do not severely restrict the possibility of fabricating metal-oxide-semiconductor field effect transistors working in the depletion or the enhancement mode.     

Monomeric antioxidants. An 1H-NMR spectrometry study of their homopolymerization

Summary The polymerization behaviour of 3,5-di-tert-butyl-4-hydroxy-benzylmethacrylate (I), trans-3,5-di-tert-butyl-4-hydroxycinnamic acid (II), 3,5-di-tert-butyl-4-hydroxystyrene (III) and N-(3,5-ditert-butyl-4-hydroxybenzyl)maleimide (IV) was investigated. These monomeric antioxidants were polymerized in aromatic solvents, in the presence of usual radical initiators, by refluxing under nitrogen. An ¹H-NMR spectrometry method for the calculation of polymerization conversion was developed. The disappearance of the monomer double bond was followed using dibenzyl ether as an internal standard. The reactivity of these monomers, all showing the same antioxidant functionality, decreased in the order IV>I>III. The acid antioxidant (II) was not capable of polymerization.