67,724 research outputs found
Commercial equity: the Quistclose trust and asset recovery
This paper examines the impact of equitable principles on the sphere of commercial law. It will make particular reference to the effect of the incursion of equity on ordinary creditors with regard to obtaining priorities in cases of insolvency. It will analyze the Quistclose trust and show how this type of trust may be used to obtain an advantage by those who would otherwise be ordinary creditors. It will refer to the use of equitable tracing to recover assets in a money-laundering scheme The paper will suggest that judicial acceptance of the concept of the remedial constructive trusts has enhanced the development of proprietary restitutionary remedies in commercial transactions where no proprietary remedy would have previously existed
AROMA: Automatic Generation of Radio Maps for Localization Systems
WLAN localization has become an active research field recently. Due to the
wide WLAN deployment, WLAN localization provides ubiquitous coverage and adds
to the value of the wireless network by providing the location of its users
without using any additional hardware. However, WLAN localization systems
usually require constructing a radio map, which is a major barrier of WLAN
localization systems' deployment. The radio map stores information about the
signal strength from different signal strength streams at selected locations in
the site of interest. Typical construction of a radio map involves measurements
and calibrations making it a tedious and time-consuming operation. In this
paper, we present the AROMA system that automatically constructs accurate
active and passive radio maps for both device-based and device-free WLAN
localization systems. AROMA has three main goals: high accuracy, low
computational requirements, and minimum user overhead. To achieve high
accuracy, AROMA uses 3D ray tracing enhanced with the uniform theory of
diffraction (UTD) to model the electric field behavior and the human shadowing
effect. AROMA also automates a number of routine tasks, such as importing
building models and automatic sampling of the area of interest, to reduce the
user's overhead. Finally, AROMA uses a number of optimization techniques to
reduce the computational requirements. We present our system architecture and
describe the details of its different components that allow AROMA to achieve
its goals. We evaluate AROMA in two different testbeds. Our experiments show
that the predicted signal strength differs from the measurements by a maximum
average absolute error of 3.18 dBm achieving a maximum localization error of
2.44m for both the device-based and device-free cases.Comment: 14 pages, 17 figure
General relativistic Poynting-Robertson effect to diagnose wormholes existence: static and spherically symmetric case
We derive the equations of motion of a test particle in the equatorial plane
around a static and spherically symmetric wormhole influenced by a radiation
field including the general relativistic Poynting-Robertson effect. From the
analysis of this dynamical system, we develop a diagnostic to distinguish a
black hole from a wormhole, which can be timely supported by several and
different observational data. This procedure is based on the possibility of
having some wormhole metrics, which smoothly connect to the Schwarzschild
metric in a small transition surface layer very close to the black hole event
horizon. To detect such a metric-change, we analyse the emission proprieties
from the critical hypersurface (stable region where radiation and gravitational
fields balance) together with those from an accretion disk in the Schwarzschild
spacetime toward a distant observer. Indeed, if the observational data are well
fitted within such model, it immediately implies the existence of a black hole;
while in case of strong departures from such description it means that a
wormhole could be present. Finally, we discuss our results and draw the
conclusions.Comment: 17 pages, 11 figures, 1 Table. Paper accepted on April 30, 2020 on
Physical Review
General Relativistic Ray-Tracing Method for Estimating the Energy and Momentum Deposition by Neutrino Pair Annihilation in Collapsars
Bearing in mind the application to the collapsar models of gamma-ray bursts
(GRBs), we develop a numerical scheme and code for estimating the deposition of
energy and momentum due to the neutrino pair annihilation () in the vicinity of accretion tori around a Kerr
black hole. Our code is designed to solve the general relativistic neutrino
transfer by a ray-tracing method. To solve the collisional Boltzmann equation
in curved spacetime, we numerically integrate the so-called rendering equation
along the null geodesics. For the neutrino opacity, the charged-current
-processes are taken into account, which are dominant in the vicinity of
the accretion tori. The numerical accuracy of the developed code is
certificated by several tests, in which we show comparisons with the
corresponding analytic solutions. Based on the hydrodynamical data in our
collapsar simulation, we estimate the annihilation rates in a post-processing
manner. Increasing the Kerr parameter from 0 to 1, it is found that the general
relativistic effect can increase the local energy deposition rate by about one
order of magnitude, and the net energy deposition rate by several tens of
percents. After the accretion disk settles into a stationary state (typically
later than s from the onset of gravitational collapse), we point out
that the neutrino-heating timescale in the vicinity of the polar funnel region
can be shorter than the dynamical timescale. Our results suggest the neutrino
pair annihilation has a potential importance equal to the conventional
magnetohydrodynamic mechanism for igniting the GRB fireballs.Comment: 33 pages, 15 figures, accepted to the Ap
Interplay between multiple scattering, emission, and absorption of light in the phosphor of a white light-emitting diode
We study light transport in phosphor plates of white light-emitting diodes
(LEDs). We measure the broadband diffuse transmission through phosphor plates
of varying YAG:Ce density. We distinguish the spectral ranges where
absorption, scattering, and re-emission dominate. Using diffusion theory, we
derive the transport and absorption mean free paths from first principles. We
find that both transport and absorption mean free paths are on the order of the
plate thickness. This means that phosphors in commercial LEDs operate well
within an intriguing albedo range around 0.7. We discuss how salient parameters
that can be derived from first principles control the optical properties of a
white LED.Comment: 14 pages, 9 figure
A Self-Assembled Microlensing Rotational Probe
A technique to measure microscopic rotational motion is presented.
When a small fluorescent polystyrene microsphere is attached to a larger
polystyrene microsphere, the larger sphere acts as a lens for the smaller
microsphere and provides an optical signal that is a strong function of the
azimuthal angle. We demonstrate the technique by measuring the rotational
diffusion constant of the microsphere in solutions of varying viscosity and
discuss the feasibility of using this probe to measure rotational motion of
biological systems.Comment: 3 pages with 2 figures (eps format). Paper has been submitted to
Applied Physics Letter
Tracing magnetic separators and their dependence on IMF clock angle in global magnetospheric simulations
A new, efficient, and highly accurate method for tracing magnetic separators
in global magnetospheric simulations with arbitrary clock angle is presented.
The technique is to begin at a magnetic null and iteratively march along the
separator by finding where four magnetic topologies meet on a spherical
surface. The technique is verified using exact solutions for separators
resulting from an analytic magnetic field model that superposes dipolar and
uniform magnetic fields. Global resistive magnetohydrodynamic simulations are
performed using the three-dimensional BATS-R-US code with a uniform
resistivity, in eight distinct simulations with interplanetary magnetic field
(IMF) clock angles ranging from 0 (parallel) to 180 degrees (anti-parallel).
Magnetic nulls and separators are found in the simulations, and it is shown
that separators traced here are accurate for any clock angle, unlike the last
closed field line on the Sun-Earth line that fails for southward IMF. Trends in
magnetic null locations and the structure of magnetic separators as a function
of clock angle are presented and compared with those from the analytic field
model. There are many qualitative similarities between the two models, but
quantitative differences are also noted. Dependence on solar wind density is
briefly investigated.Comment: 10 pages, 10 figures, Presented at 2012 AGU Fall Meeting and 2013
Geospace Environment Modeling (GEM) Worksho
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