Overview of DWDM/ODC Project

Abstract

This article introduces the main achievements resulting from the DWDM/ODC project. The five areas of research activity within the DWDM/ODC project cover some of the main issues of design and development of dense wavelength division multiplexing systems for transparent optical networks. These issues are: performance assessment with arbitrary optical filtering; performance of signaling formats; dispersion compensation strategies for directly and externally modulated systems in presence of nonlinear transmission-induced degradation; and the impact of noise and crosstalk in the extent of transparent optical networks. All five areas of research activity have contributed significantly to a better understanding of the limitations present in dense wavelength division multiplexing systems.     

Electromechanical effect in surface stabilized and unwound SC* liquid crystals

Applying an A.C. electric field to a planar oriented S_C* liquid crystal sample, a shear flow occurs parallel to the bounding plates and perpendicular to the helical axis. We have investigated this so-called electromechanical effect by applying different D.C. bias electric fields superposed on a constant A.C. field. The amplitude of the mechanical vibration was measured versus the bias field in different samples. From the results, structural models of the surface stabilized and unwound samples were tested.     

Temperature shift of neutrino mass in a magnetic field

The temperature shift of the neutrino mass in a constant magnetic field is calculated within the framework of the Weinberg-Salam model. The cases of weak field and low and high temperatures are considered. The contribution to the anomalous magnetic moment of the neutrino is determined. The imaginary component of the mass correction describing the reaction of decay and W-boson formation is analyzed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 3–6, December, 1987.     

A criterion of exponential dichotomy for a countable system of differential equations with quasiperiodic coefficients

We establish necesary and sufficient conditions for the exponential diehetemy with matrix projeseters of a countable system of differential equations with quasiperiodic coefficients.     

A molecular dynamics method for simulations in the canonical ensemble

A molecular dynamics simulation method which can generate configurations belonging to the canonical (T, V, N) ensemble or the constant temperature constant pressure (T, P, N) ensemble, is proposed. The physical system of interest consists of N particles (f degrees of freedom), to which an external, macroscopic variable and its conjugate momentum are added. This device allows the total energy of the physical system to fluctuate. The equilibrium distribution of the energy coincides with the canonical distribution both in momentum and in coordinate space. The method is tested for an atomic fluid (Ar) and works well.     

Averaging of Systems with Slow Variables

We justify the averaging method for systems with delay described by both slow and fast variables. The results obtained are applied to the analysis of one problem in control theory.     

Slow dynamics of a colloidal lamellar phase

We used x-ray photon correlation spectroscopy to study the dynamics in the lamellar phase of a platelet suspension as a function of the particle concentration. We measured the collective diffusion coefficient along the director of the phase, over length scales down to the interparticle distance, and quantified the hydrodynamic interaction between the particles. This interaction sets in with increasing concentration and can be described qualitatively by a simplified model. No change in the microscopic structure or dynamics is observed at the transition between the fluid and the gel-like lamellar phases.