Broken space-time symmetries and mechanisms of rectification of ac fields by nonlinear (non)adiabatic response

We consider low-dimensional dynamical systems exposed to a heat bath and to additional ac fields. The presence of these ac fields may lead to a breaking of certain spatial or temporal symmetries which in turn cause nonzero averages of relevant observables. Nonlinear (non)adiabatic response is employed to explain the effect. We consider a case of a particle in a periodic potential as an example and discuss the relevant symmetry breakings and the mechanisms of rectification of the current in such a system.Comment: 11 pages, 10 figure

The absolutely continuous spectrum of one-dimensional Schr"odinger operators

This paper deals with general structural properties of one-dimensional Schr"odinger operators with some absolutely continuous spectrum. The basic result says that the omega limit points of the potential under the shift map are reflectionless on the support of the absolutely continuous part of the spectral measure. This implies an Oracle Theorem for such potentials and Denisov-Rakhmanov type theorems. In the discrete case, for Jacobi operators, these issues were discussed in my recent paper [19]. The treatment of the continuous case in the present paper depends on the same basic ideas.Comment: references added; a few very minor change

Oscillons: an encounter with dynamical chaos in 1953?

We present evidences that Ben F. Laposky (1914-2000) might have been the first person who created a family of nonlinear analog circuits that allowed him to observe chaotic attractors and other trademarks of nonlinear science as early as 1953.Comment: accepted to Chao

The mean electromotive force due to turbulence of a conducting fluid in the presence of mean flow

The mean electromotive force caused by turbulence of an electrically conducting fluid, which plays a central part in mean--field electrodynamics, is calculated for a rotating fluid. Going beyond most of the investigations on this topic, an additional mean motion in the rotating frame is taken into account. One motivation for our investigation originates from a planned laboratory experiment with a Ponomarenko-like dynamo. In view of this application the second--order correlation approximation is used. The investigation is of high interest in astrophysical context, too. Some contributions to the mean electromotive are revealed which have not been considered so far, in particular contributions to the $\alpha$--effect and related effects due to the gradient of the mean velocity. Their relevance for dynamo processes is discussed. In a forthcoming paper the results reported here will be specified to the situation in the laboratory and partially compared with experimental findings.Comment: 16 pages, 2 figures, in PRE pres

Innovational development for transitional economy: Russia case study

The purpose of this article is to develop mechanisms of innovational development for countries with transitional economies. The methodological base of the research consists of a factor analysis of the structure of GDP adapted to the analysis of the innovational development of countries with a transitional economy, distinguishing the innovational sphere of the economy, the structure of manufactured innovational goods, the structure of the creation of leading production technologies, and the structure of the leading production technologies. During the course of the research, the authors determined the key problems inhibiting innovational development in Russia and other countries with transitional economies, determined the most important preconditions of Russia's transition to an innovation-oriented type of economic development, and offered instruments for Russia's transition to an innovation-oriented type of economic development. As a result, the authors developed working mechanisms of the innovational development of countries with a transitional economy. The authors come to the conclusion that the innovational development of an economy is an important condition for the adaptation of countries with a transitional economy to new market conditions because it allows the private manufacturing of products that are competitive in global markets. High innovational activity is one of the most important features of a market economy compared to an administrative & command economic system; thus, without the development of innovations, transitioning to a new type of economic system is impossible for countries with a transitional economy

ОЦЕНКА ЭНЕРГЕТИЧЕСКОЙ ЕФФЕКТИВНОСТИ ПАРАЛЛЕЛЬНОГО КВАЗИРЕЗОНАНСНОГО ПРЕОБРАЗОВАТЕЛЯ

The processing in experimental specimen of parallel quasi-resonant zero current switch converter (QR-ZCS) is considered. The advantages of QR-ZCS’ structural design are shown. The results of experimental researches of energy efficiency of parallel QR-ZCS converter are published. References 3, tables 1, figures 2.Исследована работа экспериментального макета параллельного квазирезонансного импульсного преобразователя, переключаемого при нулевом токе(КРИП-ПНТ). Показаны достоинства его структурного построения. Приведены результаты экспериментальных исследований энергетической эффективности параллельного КРИП- ПНТ. Библ. 3, табл. 1, рис. 2

Onset of dendritic flux avalanches in superconducting films

We report a detailed comparison of experimental data and theoretical predictions for the dendritic flux instability, believed to be a generic behavior of type-II superconducting films. It is shown that a thermo-magnetic model published very recently [Phys. Rev. B 73, 014512 (2006)] gives an excellent quantitative description of key features like the instability onset (first dendrite appearance) magnetic field, and how the onset field depends on both temperature and sample size. The measurements were made using magneto-optical imaging on a series of different strip-shaped samples of MgB2. Excellent agreement is also obtained by reanalyzing data previously published for Nb.Comment: 4 pages, 5 figure

Broadband mode in proton-precession magnetometers with signal processing regression methods

The choice of the signal processing method may improve characteristics of the measuring device. We consider the measurement error of signal processing regression methods for a quasi-harmonic signal generated in a frequency selective device. The results are applied to analyze the difference between the simple period meter processing and regression algorithms using measurement cycle signal data in proton-precession magnetometers. Dependences of the measurement error on the sensor quality factor and frequency of nuclear precession are obtained. It is shown that regression methods considerably widen the registration bandwidth and relax the requirements on the magnetometer hardware, and thus affect the optimization criteria of the registration system. © 2014 IOP Publishing Ltd

Relation between self-organized criticality and grain aspect ratio in granular piles

We investigate experimentally whether self-organized criticality (SOC) occurs in granular piles composed of different grains, namely, rice, lentils, quinoa, and mung beans. These four grains were selected to have different aspect ratios, from oblong to oblate. As a function of aspect ratio, we determined the growth (β) and roughness (α) exponents, the avalanche fractal dimension (D), the avalanche size distribution exponent (τ), the critical angle (γ), and its fluctuation. At superficial inspection, three types of grains seem to have power-law-distributed avalanches with a well-defined τ. However, only rice is truly SOC if we take three criteria into account: a power-law-shaped avalanche size distribution, finite size scaling, and a universal scaling relation relating characteristic exponents. We study SOC as a spatiotemporal fractal; in particular, we study the spatial structure of criticality from local observation of the slope angle. From the fluctuation of the slope angle we conclude that greater fluctuation (and thus bigger avalanches) happen in piles consisting of grains with larger aspect ratio. © 2012 American Physical Society