An exact relation between Eulerian and Lagrangian velocity increment statistics

We present a formal connection between Lagrangian and Eulerian velocity increment distributions which is applicable to a wide range of turbulent systems ranging from turbulence in incompressible fluids to magnetohydrodynamic turbulence. For the case of the inverse cascade regime of two-dimensional turbulence we numerically estimate the transition probabilities involved in this connection. In this context we are able to directly identify the processes leading to strongly non-Gaussian statistics for the Lagrangian velocity increments.Comment: 5 pages, 3 figure

A Nonlinear Dynamic Interactive Decision Analysis and Support System (DIDASS/N)

The Interactive Decision Analysis group at IIASA has developed a decision analysis and support system, called "DIDASS". Based on the Reference Point Approach for multicriteria analysis, it is an attempt to combine the analytical power of the "hard" computer model with the qualitative assessments of the decision maker. In general, DIDASS is capable of dealing with both linear and nonlinear problems. Theoretical and practical tests for solving nonlinear problems of regional water policies in open-pit mining areas have elucidated the need for an especially designed nonlinear DIDASS version. Following the presentation of the extended nonlinear version, DIDASS/N is described. DIDASS/N has been developed in collaboration between the Interactive Decision Analysis Group and the Regional Water Policies Project at IIASA. DIDASS/N has been written in FORTRAN 77. The use of operating-system-dependent statements or commands has been avoided

Interactive Decision Analysis in Energy Planning and Policy Assessment

In recent years, there has been considerable fruitful collaboration between the System and Decision Sciences (SDS) Program and the Energy Project at IIASA. This paper gives an overview of this joint work, which involves the use of methodological tools developed in SDS to analyze decision situations based on models constructed in the Energy Project. The paper starts with a study of the use of the earliest version of DIDASS in conjunction with the energy supply model MESSAGE. It then describes how construction of more advanced energy models such as MESSAGE II, SEMA (an Austrian energy model), and GATE (a model of gas trade in Europe) took place in parallel with the development of an interactive multiple-criteria LP-solver (IMM), which represents a first step towards the integration of modeling and optimization processes in the analysis of complex decision situations. We hope that such collaboration will continue to provide a driving force for advances in different areas of IIASA research

Enhancement of Transparency and Adaptability by Online Tracking of Enterprise Processes

Enterprises are seeking novel approaches to reduce cost in complying with regulations and requirements from original equipment manufacturers. Consequently, enterprises are investing in manufacturing execution system (MES) solutions for realizing these requirements. However, most of the MES solutions do not support processing of real-time process data acquired from shop floor for online monitoring and control of enterprise processes. Further, monitoring of enterprise processes can be classified into online tracking and passive tracing. In the contribution, a framework is envisaged for online tracking of enterprise processes based on MES concepts. This framework has been validated in an industrial scenario

Anisotropic and strong negative magneto-resistance in the three-dimensional topological insulator Bi2Se3

We report on high-field angle-dependent magneto-transport measurements on epitaxial thin films of Bi2Se3, a three-dimensional topological insulator. At low temperature, we observe quantum oscillations that demonstrate the simultaneous presence of bulk and surface carriers. The magneto- resistance of Bi2Se3 is found to be highly anisotropic. In the presence of a parallel electric and magnetic field, we observe a strong negative longitudinal magneto-resistance that has been consid- ered as a smoking-gun for the presence of chiral fermions in a certain class of semi-metals due to the so-called axial anomaly. Its observation in a three-dimensional topological insulator implies that the axial anomaly may be in fact a far more generic phenomenon than originally thought.Comment: 6 pages, 4 figure

Fluid Simulations of Three-Dimensional Reconnection that Capture the Lower-Hybrid Drift Instability

Fluid models that approximate kinetic effects have received attention recently in the modelling of large scale plasmas such as planetary magnetospheres. In three-dimensional reconnection, both reconnection itself and current sheet instabilities need to be represented appropriately. We show that a heat flux closure based on pressure gradients enables a ten moment fluid model to capture key properties of the lower-hybrid drift instability (LHDI) within a reconnection simulation. Characteristics of the instability are examined with kinetic and fluid continuum models, and its role in the three-dimensional reconnection simulation is analysed. The saturation level of the electromagnetic LHDI is higher than expected which leads to strong kinking of the current sheet. Therefore, the magnitude of the initial perturbation has significant impact on the resulting turbulence.Comment: 20 pages, 9 figure