763,829 research outputs found
Online Casino Advertising: Testing the Limits of Commercial Speech
<span style="font-family: TimesNewRoman;"><font face="TimesNewRoman"><p align="left">The advent of the Internet has revolutionized the daily lives of everyone by giving increased access to information and consumer transactions, while also adding change and further complexity to the law. Gambling has adapted to the arrival of the Internet with online sports books</p></font></span><p align="left"><span style="font-family: TimesNewRoman; font-size: xx-small;"><span style="font-family: TimesNewRoman; font-size: xx-small;">2 </span></span><span style="font-family: TimesNewRoman;">and online casino gambling,</span><span style="font-family: TimesNewRoman; font-size: xx-small;"><span style="font-family: TimesNewRoman; font-size: xx-small;">3 </span></span><span style="font-family: TimesNewRoman;">both developing a presence on the Internet. These new online casinos have begun to advertise both on the Internet and through more traditional broadcasting, like radio and television.</span><span style="font-family: TimesNewRoman; font-size: xx-small;"><span style="font-family: TimesNewRoman; font-size: xx-small;">4 </span></span><span style="font-family: TimesNewRoman;">As a result, the Department of Justice has begun to crack down on online casino advertisers, primarily by threatening prosecution against advertisers through the Wire Act (18 U.S.C. § 1084).</span></p
Non-axisymmetric relativistic Bondi-Hoyle accretion onto a Kerr black hole
In our program of studying numerically the so-called Bondi-Hoyle accretion in
the fully relativistic regime, we present here first results concerning the
evolution of matter accreting supersonically onto a rotating (Kerr) black hole.
These computations generalize previous results where the non-rotating
(Schwarzschild) case was extensively considered. We parametrize our initial
data by the asymptotic conditions for the fluid and explore the dependence of
the solution on the angular momentum of the black hole. Towards quantifying the
robustness of our numerical results, we use two different geometrical
foliations of the black hole spacetime, the standard form of the Kerr metric in
Boyer-Lindquist coordinates as well as its Kerr-Schild form, which is free of
coordinate singularities at the black hole horizon. We demonstrate some
important advantages of using such horizon adapted coordinate systems.
Our numerical study indicates that regardless of the value of the black hole
spin the final accretion pattern is always stable, leading to constant
accretion rates of mass and momentum. The flow is characterized by a strong
tail shock, which, unlike the Schwarzschild case, is increasingly wrapped
around the central black hole as the hole angular momentum increases. The
rotation induced asymmetry in the pressure field implies that besides the well
known drag, the black hole will experience also a lift normal to the flow
direction. This situation exhibits some analogies with the Magnus effect of
classical fluid dynamics.Comment: 33 pages, 20 figures, submited to MNRA
Analysis and optimization of energy usage in Supermarkets
The thesis performed in this research is focused on a particular type of energy system, energy systems in supermarkets. As supermarkets are high-energy using buildings, their energy system optimization has been investigated in recent years, with the main focus in the refrigeration system, which can take up to 50% of the total energy of the supermarket. However, the complexity and interconnections of the different systems increase the difficulty of the task.
The aim of this work is to contribute in SuperSmart project, an EU project which main objective is to reduce the impact of the supermarket sector overall Europe, through the development of an ecolabel criteria. To simulate the energy use in supermarkets, CyberMart software is bring forward. This tool is used both to determine the parameters which have a higher impact in the supermarket energy system and perform energy representation based on those parameters. Finally, the design of the most energy efficient store is also presented.
According to CyberMart, some of the most determinant parameters in the supermarket energy system are refrigeration capacities, plug in cabinets used, lights power, heating system technologies used and whether the cabinets are covered or not. Using some of these parameters plus other important characteristics from the store, two energy representations are performed. The linear energy representation provides the increase or decrease of kWh per each parameter, enabling supermarkets owners to compare different parameters within the global system.
These representations, which distinguish between heat recovery and floating condensing technologies, conclude that the most important parameters in the global system are the temperature inside at winter and the refrigeration capacity. However, some unreasonable events appear, like the decline of electricity demand when the height of the building increases or the drop of heat demand with the rise of opening hours. These facts occur due to the high complexity of the global system, implying different connections between the sub-systems within CyberMart.
Concerning the most energy efficient store located in Stockholm, the obtained results show the most energy efficient supermarket is composed by CO2 refrigeration and heating systems, and a R410_A air conditioning system. The optimal electricity use of each establishment size from large to small area is 382, 394, 390 and 281 kWh/m2*year respectively, with the highest values obtained in Supermarkets and Discount stores, due to their higher rate of refrigeration power per store area
Dynamics of thick discs around Schwarzschild-de Sitter black holes
We consider the effects of a cosmological constant on the dynamics of
constant angular momentum discs orbiting Schwarzschild-de Sitter black holes.
The motivation behind this study is to investigate whether the presence of a
radial force contrasting the black hole's gravitational attraction can
influence the occurrence of the runaway instability, a robust feature of the
dynamics of constant angular momentum tori in Schwarzschild and Kerr
spacetimes. In addition to the inner cusp near the black hole horizon through
which matter can accrete onto the black hole, in fact, a positive cosmological
constant introduces also an outer cusp through which matter can leave the torus
without accreting onto the black hole. To assess the impact of this outflow on
the development of the instability we have performed time-dependent and
axisymmetric hydrodynamical simulations of equilibrium initial configurations
in a sequence of background spacetimes of Schwarzschild-de Sitter black holes
with increasing masses. The simulations have been performed with an unrealistic
value for the cosmological constant which, however, yields sufficiently small
discs to be resolved accurately on numerical grids and thus provides a first
qualitative picture of the dynamics. The calculations, carried out for a wide
range of initial conditions, show that the mass-loss from the outer cusp can
have a considerable impact on the instability, with the latter being rapidly
suppressed if the outflow is large enough.Comment: 12 pages; A&A, in pres
Local characteristic algorithms for relativistic hydrodynamics
Numerical schemes for the general relativistic hydrodynamic equations are
discussed. The use of conservative algorithms based upon the characteristic
structure of those equations, developed during the last decade building on
ideas first applied in Newtonian hydrodynamics, provides a robust methodology
to obtain stable and accurate solutions even in the presence of
discontinuities. The knowledge of the wave structure of the above system is
essential in the construction of the so-called linearized Riemann solvers, a
class of numerical schemes specifically designed to solve nonlinear hyperbolic
systems of conservation laws. In the last part of the review some astrophysical
applications of such schemes, using the coupled system of the
(characteristic) Einstein and hydrodynamic equations, are also briefly
presented.Comment: 20 pages, 4 figures, To appear in the proceedings of the workshop
"The conformal structure of space-time", J. Frauendiener, H. Friedrich, eds,
Springer Lecture Notes in Physic
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