1,365 research outputs found
Persistent accelerations disentangle Lagrangian turbulence
Particles in turbulence frequently encounter extreme accelerations between
extended periods of quiescence. The occurrence of extreme events is closely
related to the intermittent spatial distribution of intense flow structures
such as vorticity filaments. This mixed history of flow conditions leads to
very complex particle statistics with a pronounced scale dependence, which
presents one of the major challenges on the way to a non-equilibrium
statistical mechanics of turbulence. Here, we introduce the notion of
persistent Lagrangian acceleration, quantified by the squared particle
acceleration coarse-grained over a viscous time scale. Conditioning Lagrangian
particle data from simulations on this coarse-grained acceleration, we find
remarkably simple, close-to-Gaussian statistics for a range of Reynolds
numbers. This opens the possibility to decompose the complex particle
statistics into much simpler sub-ensembles. Based on this observation, we
develop a comprehensive theoretical framework for Lagrangian single-particle
statistics that captures the acceleration, velocity increments as well as
single-particle dispersion
Investigations into music composition in surround sound
This research project investigates the relationship between music composition, particularly electronic pop, and sound design (the editing/mixing of sound for cinema), with its main focus on Multi-channel (Surround Sound) techniques. It proposes new practices that extend music compositional tools into embracing spatial techniques employed by sound design. My research encompasses both the conceptual development (ie spatial techniques in creating narratives) and the practical issues relating to the production and technology needed for such works
Bias in particle tracking acceleration measurement
We investigate sources of error in acceleration statistics from Lagrangian
Particle Tracking (LPT) data and demonstrate techniques to eliminate or
minimise bias errors introduced during processing. Numerical simulations of
particle tracking experiments in isotropic turbulence show that the main
sources of bias error arise from noise due to position uncertainty and
selection biases introduced during numerical differentiation. We outline the
use of independent measurements and filtering schemes to eliminate these
biases. Moreover, we test the validity of our approach in estimating the
statistical moments and probability densities of the Lagrangian acceleration.
Finally, we apply these techniques to experimental particle tracking data and
demonstrate their validity in practice with comparisons to available data from
literature. The general approach, which is not limited to acceleration
statistics, can be applied with as few as two cameras and permits a substantial
reduction in the spatial resolution and sampling rate required to adequately
measure statistics of Lagrangian acceleration
A Model of Comprehensive Unification
Comprehensive - that is, gauge and family - unification using spinors has
many attractive features, but it has been challenged to explain chirality.
Here, by combining an orbifold construction with more traditional ideas, we
address that difficulty. Our candidate model features three chiral families and
leads to an acceptable result for quantitative unification of couplings. A
potential target for accelerator and astronomical searches emerges.Comment: 5 pages, 2 figures. Published versio
Herzberg Circuit and Berry's Phase in Chirality-based Coded Qubit in a Triangular Triple Quantum Dot
We present a theoretical proposal for the Herzberg circuit and controlled
accumulation of Berry's phase in a chirality-based coded qubit in a triangular
triple quantum dot molecule with one electron spin each. The qubit is encoded
in the two degenerate states of a three spin complex with total spin .
Using a Hubbard and Heisenberg model the Herzberg circuit encircling the
degeneracy point is realized by adiabatically tuning the successive on-site
energies of quantum dots and tunnel couplings across a pair of neighbouring
dots. It is explicitly shown that encircling the degeneracy point leads to the
accumulation of the geometrical Berrys phase. We show that only triangular but
not linear quantum dot molecule allows for the generation of Berry's phase and
we discuss a protocol to detect this geometrical phase
Transitions of turbulent superstructures in generalized Kolmogorov flow
Self-organized large-scale flow structures occur in a wide range of turbulent
flows. Yet, their emergence, dynamics, and interplay with small-scale
turbulence are not well understood. Here, we investigate such self-organized
turbulent superstructures in three-dimensional turbulent Kolmogorov flow with
large-scale drag. Through extensive simulations, we uncover their
low-dimensional dynamics featuring transitions between several stable and
meta-stable large-scale structures as a function of the damping parameter. The
main dissipation mechanism for the turbulent superstructures is the generation
of small-scale turbulence, whose local structure depends strongly on the
large-scale flow. Our results elucidate the generic emergence and
low-dimensional dynamics of large-scale flow structures in fully developed
turbulence and reveal a strong coupling of large- and small-scale flow
features.Comment: v2: Revised manuscrip
Energy Spectrum of Anyons in a Magnetic Field
For the many-anyon system in external magnetic field, we derive the energy
spectrum as an exact solution of the quantum eigenvalue problem with particular
topological constraints. Our results agree with the numerical spectra recently
obtained for the 3- and the 4-anyon systems.Comment: 11 pages in Plain LaTeX (plus 4 figures available on request), DFPD
92/TH/4
Schr\"{o}dinger Fields on the Plane with non-Abelian Chern-Simons Interactions
Physical content of the nonrelativistic quantum field theory with non-Abelian
Chern-Simons interactions is clarified with the help of the equivalent first-
quantized description which we derive in any physical gauge.Comment: 12 pages, LaTex, SNUTP 94-1
- …