Standing wave oscillations in binary mixture convection: from onset via symmetry breaking to period doubling into chaos

Oscillatory solution branches of the hydrodynamic field equations describing convection in the form of a standing wave (SW) in binary fluid mixtures heated from below are determined completely for several negative Soret coefficients. Galerkin as well as finite-difference simulations were used. They were augmented by simple control methods to obtain also unstable SW states. For sufficiently negative Soret coefficients unstable SWs bifurcate subcritically out of the quiescent conductive state. They become stable via a saddle-node bifurcation when lateral phase pinning is exerted. Eventually their invariance under time-shift by half a period combined with reflexion at midheight of the fluid layer gets broken. Thereafter they terminate by undergoing a period-doubling cascade into chaos

Traveling Wave Fronts and Localized Traveling Wave Convection in Binary Fluid Mixtures

Nonlinear fronts between spatially extended traveling wave convection (TW) and quiescent fluid and spatially localized traveling waves (LTWs) are investigated in quantitative detail in the bistable regime of binary fluid mixtures heated from below. A finite-difference method is used to solve the full hydrodynamic field equations in a vertical cross section of the layer perpendicular to the convection roll axes. Results are presented for ethanol-water parameters with several strongly negative separation ratios where TW solutions bifurcate subcritically. Fronts and LTWs are compared with each other and similarities and differences are elucidated. Phase propagation out of the quiescent fluid into the convective structure entails a unique selection of the latter while fronts and interfaces where the phase moves into the quiescent state behave differently. Interpretations of various experimental observations are suggested.Comment: 46 pages, 11 figures. Accepted for publication in Phys. Rev.

Controlling the stability transfer between oppositely traveling waves and standing waves by inversion-symmetry-breaking perturbations

The effect of an externally applied flow on symmetry degenerated waves propagating into opposite directions and standing waves that exchange stability with the traveling waves via mixed states is analyzed. Wave structures that consist of spiral vortices in the counter rotating Taylor-Couette system are investigated by full numerical simulations and explained quantitatively by amplitude equations containing quintic coupling terms. The latter are appropriate to describe the influence of inversion symmetry breaking perturbations on many oscillatory instabilities with O(2) symmetry.Comment: 4 pages, 4 figure

Technologische Alternativen zum herkömmlichen Einsatz von Pökelstoffen in Öko-Fleischwaren

On the basis of literature research and opinions of meat processors and other experts, this paper discusses alternatives to the currently permitted use of curing agents in the processing of organic meat. These alternatives include (i) the reduction of addition of nitrite to levels sufficient for the desired sensory properties, (ii) the in situ bacterial formation of nitrite from nitrate naturally present in added vegetable preparations, and (iii) not making use of the beneficial effects of nitrite on the colour and aroma of the product at all. Measures to be taken to compensate for the effects of nitrite, as well as problems in implementation of technological alternatives are discussed

Pattern selection as a nonlinear eigenvalue problem

A unique pattern selection in the absolutely unstable regime of driven, nonlinear, open-flow systems is reviewed. It has recently been found in numerical simulations of propagating vortex structures occuring in Taylor-Couette and Rayleigh-Benard systems subject to an externally imposed through-flow. Unlike the stationary patterns in systems without through-flow the spatiotemporal structures of propagating vortices are independent of parameter history, initial conditions, and system length. They do, however, depend on the boundary conditions in addition to the driving rate and the through-flow rate. Our analysis of the Ginzburg-Landau amplitude equation elucidates how the pattern selection can be described by a nonlinear eigenvalue problem with the frequency being the eigenvalue. Approaching the border between absolute and convective instability the eigenvalue problem becomes effectively linear and the selection mechanism approaches that of linear front propagation. PACS: 47.54.+r,47.20.Ky,47.32.-y,47.20.FtComment: 18 pages in Postsript format including 5 figures, to appear in: Lecture Notes in Physics, "Nonlinear Physics of Complex Sytems -- Current Status and Future Trends", Eds. J. Parisi, S. C. Mueller, and W. Zimmermann (Springer, Berlin, 1996

Satisfying the Einstein-Podolsky-Rosen criterion with massive particles

In 1935, Einstein, Podolsky and Rosen (EPR) questioned the completeness of quantum mechanics by devising a quantum state of two massive particles with maximally correlated space and momentum coordinates. The EPR criterion qualifies such continuous-variable entangled states, where a measurement of one subsystem seemingly allows for a prediction of the second subsystem beyond the Heisenberg uncertainty relation. Up to now, continuous-variable EPR correlations have only been created with photons, while the demonstration of such strongly correlated states with massive particles is still outstanding. Here, we report on the creation of an EPR-correlated two-mode squeezed state in an ultracold atomic ensemble. The state shows an EPR entanglement parameter of 0.18(3), which is 2.4 standard deviations below the threshold 1/4 of the EPR criterion. We also present a full tomographic reconstruction of the underlying many-particle quantum state. The state presents a resource for tests of quantum nonlocality and a wide variety of applications in the field of continuous-variable quantum information and metrology.Comment: 8 pages, 7 figure

Проектирование релейной защиты автотрансформатора 500/220/10 кВ подстанции «Томская» Томской энергосистемы

В работе проектируется релейная защита автотрансформатора 500/220/10 кВ ПС Томская Томской энергосистемы, выполнен литературный обзор различных видов релейной защиты, представлены характеристики релейной защиты. Выполнены расчеты, на основе которых осуществлен подбор необходимого оборудования.The design of relay protection for an autotransformer 500/220/10 kV substation Tomsk Tomsk power system is designed, a literature review of various types of relay protection is carried out, the characteristics of relay protection are presented. The calculations based on which the selection of the necessary equipment was carried out