81,458 research outputs found
Microscopic chaos and diffusion
We investigate the connections between microscopic chaos, defined on a
dynamical level and arising from collisions between molecules, and diffusion,
characterized by a mean square displacement proportional to the time. We use a
number of models involving a single particle moving in two dimensions and
colliding with fixed scatterers. We find that a number of microscopically
nonchaotic models exhibit diffusion, and that the standard methods of chaotic
time series analysis are ill suited to the problem of distinguishing between
chaotic and nonchaotic microscopic dynamics. However, we show that periodic
orbits play an important role in our models, in that their different properties
in chaotic and nonchaotic systems can be used to distinguish such systems at
the level of time series analysis, and in systems with absorbing boundaries.
Our findings are relevant to experiments aimed at verifying the existence of
chaoticity and related dynamical properties on a microscopic level in diffusive
systems.Comment: 28 pages revtex, 14 figures incorporated with epsfig; see also
chao-dyn/9904041; revised to clarify the definition of chaos and include
discussion of a mixed model with both square and circular scatterer
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Antecedents and consequences of market orientation in universities: Literature review and conceptual framework
Recent developments in marketing theory have resulted in the conceptualisation of the market orientation construct in different cultural and industrial settings. However, there is little research investigating the applicability of market orientation in the higher education context. Building on the existing literature on market orientation and higher education marketing, the authors propose a theoretical framework of market orientation from a higher education management perspective. The framework analysis leads to propositions relating to the antecedents and consequences of market oriented universities. On the basis of the formulated propositions, the authors conclude with a discussion of the implications both for academia and practice and further research
Thermal breakdown of coherent backscattering: a case study of quantum duality
We investigate coherent backscattering of light by two harmonically trapped
atoms in the light of quantitative quantum duality. Including recoil and
Doppler shift close to an optical resonance, we calculate the interference
visibility as well as the amount of which-path information, both for zero and
finite temperature.Comment: published version with minor changes and an added figur
Atmospheric turbulence and superstatistics
Nonequilibrium systems with large-scale fluctuations of a suitable system
parameter are often effectively described by a superposition of two statistics,
a superstatistics. Here we illustrate this concept by analysing experimental
data of fluctuations in atmospheric wind velocity differences at Florence
airport.Comment: 9 pages, 4 figures. New version to appear in Europhysics News (2005
Determining crustal strain rates with a spaceborne geodynamics ranging system. 2: Station coordinate analysis
The use of a spaceborne geodynamics ranging system for determining crustal strain rates is analyzed. The use of site coordinates rather than intersite baseline distances for the strain rate determinations is emphasized. After discussing the analytical techniques which are to be employed, numerical results are presented which suggest that the use of site coordinates would result in a 20-70% improvement in the precision of the deduced values of straining. Precision of a few parts in 10 to the 9th power would be achievable with simple geometrics and a decade or two of measurements; precisions of a few parts in 10 to the 8th power would be achievable in a few years. A consideration of possible correlations among the derived target site coordinates leads to the conclusion that, with the proper choice of coordinate systems, the correlations can be made small and non-detrimental to the strain rate determinations
Use of active control technology to improve ride qualities of large transport aircraft
Analyses, construction and flight testing of two systems: Beta-vane and Modal Suppression Augmentation System (MSAS), which were developed to suppress gust induced lateral accelerations of large aircraft, are described. The 747 transport was used as the test vehicle. The purpose of the Beta-vane system is to reduce acceleration levels at the dutch roll frequency whereas the function of the MSAS system is to reduce accelerations due to flexible body motions caused by turbulence. Data from flight test, with both systems engaged shows a 50 to 70 percent reduction in lateral aft body acceleration levels. Furthermore, it is suggested that present day techniques used for developing dynamic equations of motion in the flexible mode region are limited
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