9,181 research outputs found
Correlations of a bound interface over a random substrate
The correlation function of a one-dimensional interface over a random
substrate, bound to the substrate by a pressure term, is studied by Monte-Carlo
simulation. It is found that the height correlation , averaged
over the substrate disorder, fits a form exp(-(j/b)^c) to a surprising
precision in the full range of j where the correlation is non-negligible. The
exponent c increases from 1.0 to 1.5 when the interface tension is taken larger
and larger.Comment: 7 pages, 5 figure
Frequency response of an axial-flow compressor exposed to inlet pressure perturbations
Experimental results of a series of engine tests designed to obtain the stage dynamics of an eight-stage axial-flow compressor over the frequency range of 0.5 to 200 hertz are presented. The total pressure at the compressor face was varied by means of a secondary air jet system installed in the engine inlet and positioned to oppose the primary airflow. Total-pressure probes located at each compressor stage were used to obtain the frequency response of each compressor-stage total pressure to the average compressor-inlet total pressure. The engine operating conditions were chosen to illustrate the effects of changing the rotor speed, changing the exhaust nozzle area, and isolating the compressor discharge pressure perturbations from the fuel control and hence, the fuel flow
Monte Carlo simulations of the directional-ordering transition in the two-dimensional classical and quantum compass model
A comprehensive study of the two-dimensional (2D) compass model on the square
lattice is performed for classical and quantum spin degrees of freedom using
Monte Carlo and quantum Monte Carlo methods. We employ state-of-the-art
implementations using Metropolis, stochastic series expansion and parallel
tempering techniques to obtain the critical ordering temperatures and critical
exponents. In a pre-investigation we reconsider the classical compass model
where we study and contrast the finite-size scaling behavior of ordinary
periodic boundary conditions against annealed boundary conditions. It is shown
that periodic boundary conditions suffer from extreme finite-size effects which
might be caused by closed loop excitations on the torus. These excitations also
appear to have severe effects on the Binder parameter. On this footing we
report on a systematic Monte Carlo study of the quantum compass model. Our
numerical results are at odds with recent literature on the subject which we
trace back to neglecting the strong finite-size effects on periodic lattices.
The critical temperatures are obtained as and
for the classical and quantum version, respectively,
and our data support a transition in the 2D Ising universality class for both
cases.Comment: 8 pages, 7 figures, differs slightly from published versio
Source Mechanism Determination of low Magnitude Earthquakes and Derivation of the Eastern African Stress Pattern
X-ray response of silicon surface barrier diodes at 8 and 17.5 keV: evidence that the x-ray sensitive depth is not generally the depletion depth
Decision-analytic frameworks for multi-hazard mitigation and adaptation
Developing effective decision-support for multiple hazards needs to build on a foundation of existing research into best practices for the management of single hazards analysis. This comes from the hazards literature, recent and ongoing EU research projects, and from the climate vulnerability literature, in which the theoretical focus on multiple drivers of vulnerability is already well established. The first part of this task will rely on a desk study of established management practices and decision-analytic methods. The latter include several standard methods for conducting sound formal decision-analysis, including cost-benefit analysis, risk- benefit analysis, and multi-criteria analysis. Each of these has its strengths, weaknesses, and set to best practices in particular contexts. The second part of this task will identify these in the case of multiple hazards, and appraise how they may differ in their application and appropriateness from the single-hazard case. It will rely on an application of these modeling methods to the simulated city case study
Frequency sensitive moment tensor inversion for light to moderate magnitude earthquakes in eastern Africa
Tectonic stress field in rift systems; a comparison of Rhinegraben, Baikal Rift and East African Rift
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