Reliability of Daniels systems subject to Gaussian load processes

A general method is developed for estimating reliability of Daniels systems subject to quasistatic and dynamic Gaussian load processes. The method is based on a generalization of the Slepian model, an identity involving first passage time probabilities and conditional mean crossing rates of response processes, and first/second order reliability methods. The use of the method is illustrated by an example.     

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.     

Design considerations for tunnel diode non-linear transmission lines

A tunnel diode non-linear transmission line has been investigated for second and third harmonic generation purposes. Design criteria are given and performance predictions have been obtained simulating the single diode behavior by means of a polynomial expression. An optimization of the non-linear transmission line as a harmonic generator has been obtained as a function of the number of diodes, their separation distances and the bias voltage.     

FEM modelling and experimental characterization of microbeams in presence of residual stress

Out-of-plane bending tests are here used to experimentally validate some numerical models of microbeams actuated by the electric field. Out-of-plane bending microcantilevers and clamped–clamped microbeams often suffer the presence of residual strain and stress, respectively, which affect their static and dynamic behaviour and pull-in voltage. In case of microcantilever an accurate modelling has to include the effect of an initial curvature due to microfabrication process, while in double clamped microbeams constraints may impose a pre-loading caused by a tensile stress. So-called geometrical nonlinearity sometimes occurs, when microcantilever exhibits large displacement, or because of the mechanical coupling between axial and flexural behaviours in double clamped microbeams. Modelling this kind of nonlinearity is an additional goal of this study. Experiments demonstrated a good agreement with results of FEM approaches proposed. In the case of microbridges numerical models are used to identify the residual stress. A reverse analysis is implemented, the axial pre-stress is calculated by means of the measured pull-in voltage.     

A law of interference of electromagnetic beams of any state of coherence and polarization and the Fresnel-Arago interference laws

A new general interference law is derived for the superposition of two random electromagnetic beams of any state of coherence and of any state of polarization when the beams are transmitted through polarizers and rotators. It includes, as special cases, a variety of interference laws that apply to particular situations. Some of them have a close bearing on the classic interference experiments of Fresnel and Arago that have played a basic role in elucidating the concept of polarization of light.     

Quantum circuit’s reliability assessment with VHDL-based simulated fault injection

This paper presents a VHDL-based simulated fault injection (SFI) methodology for quantum circuits. The main objective is to attain a high error modeling capability at a technology independent level. For this purpose, gate level simulation models for quantum circuits have been developed using VHDL. The proposed methodology relies on specific techniques inspired from the simulated fault injection techniques developed for classical CMOS circuits: saboteurs and mutants. In order to perform the simulation campaigns, a library of quantum gates and simulated fault injection components has been developed. The simulation results show that a wide range of quantum faults and error models has been addressed. Furthermore, a comparison between the two SFI techniques is presented.     

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.     

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.