Self-similar signature of the active solar corona within the inertial range of solar-wind turbulence

We quantify the scaling of magnetic energy density in the inertial range of solar-wind turbulence seen in situ at 1 AU with respect to solar activity. At solar maximum, when the coronal magnetic field is dynamic and topologically complex, we find self-similar scaling in the solar wind, whereas at solar minimum, when the coronal fields are more ordered, we find multifractality. This quantifies the solar-wind signature that is of direct coronal origin and distinguishes it from that of local MHD turbulence, with quantitative implications for coronal heating of the solar wind

Kinetic Signatures and Intermittent Turbulence in the Solar Wind Plasma

A connection between kinetic processes and intermittent turbulence is observed in the solar wind plasma using measurements from the Wind spacecraft at 1 AU. In particular, kinetic effects such as temperature anisotropy and plasma heating are concentrated near coherent structures, such as current sheets, which are non-uniformly distributed in space. Furthermore, these coherent structures are preferentially found in plasma unstable to the mirror and firehose instabilities. The inhomogeneous heating in these regions, which is present in both the magnetic field parallel and perpendicular temperature components, results in protons at least 3-4 times hotter than under typical stable plasma conditions. These results offer a new understanding of kinetic processes in a turbulent regime, where linear Vlasov theory is not sufficient to explain the inhomogeneous plasma dynamics operating near non-Gaussian structures.Comment: 4 pages, 3 figures, submitted to Physical Review Letter

Magnetic Reconnection and Intermittent Turbulence in the Solar Wind

A statistical relationship between magnetic reconnection, current sheets and intermittent turbulence in the solar wind is reported for the first time using in-situ measurements from the Wind spacecraft at 1 AU. We identify intermittency as non-Gaussian fluctuations in increments of the magnetic field vector, $\mathbf{B}$, that are spatially and temporally non-uniform. The reconnection events and current sheets are found to be concentrated in intervals of intermittent turbulence, identified using the partial variance of increments method: within the most non-Gaussian 1% of fluctuations in $\mathbf{B}$, we find 87%-92% of reconnection exhausts and $\sim$9% of current sheets. Also, the likelihood that an identified current sheet will also correspond to a reconnection exhaust increases dramatically as the least intermittent fluctuations are removed from the dataset. Hence, the turbulent solar wind contains a hierarchy of intermittent magnetic field structures that are increasingly linked to current sheets, which in turn are progressively more likely to correspond to sites of magnetic reconnection. These results could have far reaching implications for laboratory and astrophysical plasmas where turbulence and magnetic reconnection are ubiquitous.Comment: 5 pages, 3 figures, submitted to Physical Review Letter

Features of Strategic Potential as the Basis of the System of Strategic Management of Enterprise Competitiveness

An important condition for the effective strategic development of an enterprise is a well-formed and properly implemented strategic management system. Moreover, the main condition for the effectiveness of the existing system should be not only the ability to achieve as fully as possible the goals of enterprise development, but also timely identified opportunities for building up sustainable competitive advantages. Since the basis of sustainable competitive advantages are the existing and/or potential capabilities of enterprise, it is proposed to select the components of its strategic potential as the basic elements of the system of strategic management of enterprise competitiveness. Concretizing the components of the strategic potential of enterprise as components of the system of strategic management of its competitiveness requires a closer definition of the essence and content of this concept. Accordingly, the aim of the article is to define as close as possible the essence and content of the concept of «strategic potential of enterprise» as a necessary condition for its rational division into components – the basis for the formation of a system of strategic management of enterprise competitiveness. To achieve this aim, the study of the existing interpretations of the concept of «strategic potential», presented by various scholars, was carried out using the methods of analysis, synthesis and abstraction; allocation of common features and allocation of directions of interpretation of the concept of «strategic potential» – using the methods of comparison, grouping, component analysis; closer definition of the concept of «strategic potential» – using the structural-system method. A critical analysis of the existing interpretations of the concept of «strategic potential» in the scientific literature contributed to the allocation of directions of their typologization, taking into account the main characteristic features of these interpretations. The characteristic features of the studied concepts are outlined in accordance with the parameters that determine the long-term competitive advantages of enterprise. The obtained results allowed to closer definition of the content of the concept of «strategic potential» and to allocate types of strategic potential of enterprise, which are justified to use as the basis of the system of strategic management of the enterprise competitiveness

Extreme value statistics and return intervals in long-range correlated uniform deviates

We study extremal statistics and return intervals in stationary long-range correlated sequences for which the underlying probability density function is bounded and uniform. The extremal statistics we consider e.g., maximum relative to minimum are such that the reference point from which the maximum is measured is itself a random quantity. We analytically calculate the limiting distributions for independent and identically distributed random variables, and use these as a reference point for correlated cases. The distributions are different from that of the maximum itself i.e., a Weibull distribution, reflecting the fact that the distribution of the reference point either dominates over or convolves with the distribution of the maximum. The functional form of the limiting distributions is unaffected by correlations, although the convergence is slower. We show that our findings can be directly generalized to a wide class of stochastic processes. We also analyze return interval distributions, and compare them to recent conjectures of their functional form

Parametric study of prospective early commercial MHD power plants (PSPEC). General Electric Company, task 1: Parametric analysis

The performance and cost of moderate technology coal-fired open cycle MHD/steam power plant designs which can be expected to require a shorter development time and have a lower development cost than previously considered mature OCMHD/steam plants were determined. Three base cases were considered: an indirectly-fired high temperature air heater (HTAH) subsystem delivering air at 2700 F, fired by a state of the art atmospheric pressure gasifier, and the HTAH subsystem was deleted and oxygen enrichment was used to obtain requisite MHD combustion temperature. Coal pile to bus bar efficiencies in ease case 1 ranged from 41.4% to 42.9%, and cost of electricity (COE) was highest of the three base cases. For base case 2 the efficiency range was 42.0% to 45.6%, and COE was lowest. For base case 3 the efficiency range was 42.9% to 44.4%, and COE was intermediate. The best parametric cases in bases cases 2 and 3 are recommended for conceptual design. Eventual choice between these approaches is dependent on further evaluation of the tradeoffs among HTAH development risk, O2 plant integration, and further refinements of comparative costs

IMF clock angle control of multifractality in ionospheric velocity fluctuations

We present an analysis of 8 years of meridional line-of-sight ionospheric plasma velocity measurements from the Halley SuperDARN radar which investigates the effect of the interplanetary magnetic field (IMF) clock angle on the scaling exponents of the first three order velocity structure functions. We only use velocity measurements made poleward of the open/closed magnetic field line boundary in the nightside ionosphere. The measured scaling exponents are consistent with multifractal Kraichnan-Iroshnikov turbulence for all clock angles but with varying intermittency that decreases to zero during purely northward IMF conditions. We thus propose that intermittency is inherited from the solar wind but also discuss other possible reasons for this relationship. Citation: Abel, G. A., M. P. Freeman, and G. Chisham (2009), IMF clock angle control of multifractality in ionospheric velocity fluctuations, Geophys. Res. Lett., 36, L19102, doi:10.1029/2009GL040336

The Process of Strategic Management of Enterprise with Account of the Peculiarities of Its Interaction with Stakeholders

The today’s conditions of operation of enterprises are characterized by limitation of certain types of resources, loss of part of markets and suppliers. This, in turn, reduces the possibilities of development of enterprises in the current period, and even more so, planning their activities for the future. Accordingly, the issue of effective determination of planned development indicators and selection of effective strategic measures to achieve them, taking into account a detailed analysis of the internal possibilities of enterprise development and favorable external factors of such development, becomes of considerable relevance. Since the possibilities of enterprise development in certain areas of its activity are limited, it is advisable to consider them through integration with attractive stakeholders for building the optimal constituents of the potential. The article specifies the process of forming a strategy for integrated development of enterprise by including in its structure the stages necessary to determine the integration capabilities of enterprise and the corresponding types of integration. The necessity of including in the proposed stage of the process of formation and implementation of the strategy of development of enterprise the following elements is substantiated: estimated indicators; risks; stages of the life cycle of the direction of activity (product, business structure, etc.); types of effects. This will allow to model the development of the enterprise under different types of integration together with scenarios for the use of integration opportunities, and it will contribute to the specification of the types and content of the integration development strategy by building various options for the relationship of the enterprise with stakeholders. The construction of such models will contribute to the effective implementation of the chosen integrated development strategy owing to a clear definition of the results and development opportunities (strategic reserves) of various options for integration entities

A nonextensive entropy approach to solar wind intermittency

The probability distributions (PDFs) of the differences of any physical variable in the intermittent, turbulent interplanetary medium are scale dependent. Strong non-Gaussianity of solar wind fluctuations applies for short time-lag spacecraft observations, corresponding to small-scale spatial separations, whereas for large scales the differences turn into a Gaussian normal distribution. These characteristics were hitherto described in the context of the log-normal, the Castaing distribution or the shell model. On the other hand, a possible explanation for nonlocality in turbulence is offered within the context of nonextensive entropy generalization by a recently introduced bi-kappa distribution, generating through a convolution of a negative-kappa core and positive-kappa halo pronounced non-Gaussian structures. The PDFs of solar wind scalar field differences are computed from WIND and ACE data for different time lags and compared with the characteristics of the theoretical bi-kappa functional, well representing the overall scale dependence of the spatial solar wind intermittency. The observed PDF characteristics for increased spatial scales are manifest in the theoretical distribution functional by enhancing the only tuning parameter $\kappa$, measuring the degree of nonextensivity where the large-scale Gaussian is approached for $\kappa \to \infty$. The nonextensive approach assures for experimental studies of solar wind intermittency independence from influence of a priori model assumptions. It is argued that the intermittency of the turbulent fluctuations should be related physically to the nonextensive character of the interplanetary medium counting for nonlocal interactions via the entropy generalization.Comment: 17 pages, 7 figures, accepted for publication in Astrophys.

Probability distributions of turbulent energy

Probability density functions (PDFs) of scale-dependent energy fluctuations, $P[\delta E(\ell)]$, are studied in high-resolution direct numerical simulations of Navier-Stokes and incompressible magnetohydrodynamic (MHD) turbulence. MHD flows with and without a strong mean magnetic field are considered. For all three systems it is found that the PDFs of inertial range energy fluctuations exhibit self-similarity and monoscaling in agreement with recent solar-wind measurements [B. Hnat et al., Geophys. Res. Lett. 29(10), 86-1 (2002)]. Furthermore, the energy PDFs exhibit similarity over all scales of the turbulent system showing no substantial qualitative change of shape as the scale of the fluctuations varies. This is in contrast to the well-known behavior of PDFs of turbulent velocity fluctuations. In all three cases under consideration the $P[\delta E(\ell)]$ resemble L\'evy-type gamma distributions $\sim \Delta^{-1}\exp(-|\delta E|/\Delta)|\delta E|^{-\gamma}$ The observed gamma distributions exhibit a scale-dependent width $\Delta(\ell)$ and a system-dependent $\gamma$. The monoscaling property reflects the inertial-range scaling of the Els\"asser-field fluctuations due to lacking Galilei invariance of $\delta E$. The appearance of L\'evy distributions is made plausible by a simple model of energy transfer.Comment: accepted for publication in PR