261,131 research outputs found
A Parameterized Algebra for Event Notification Services
Event notification services are used in various applications such as digital libraries, stock tickers, traffic control, or facility management. However, to our knowledge, a common semantics of events in event notification services has not been defined so far. In this paper, we propose a parameterized event algebra which describes the semantics of composite events for event notification systems. The parameters serve as a basis for flexible handling of duplicates in both primitive and composite events
Event-based simulation of single-photon beam splitters and Mach-Zehnder interferometers
We demonstrate that networks of locally connected processing units with a
primitive learning capability exhibit behavior that is usually only attributed
to quantum systems. We describe networks that simulate single-photon
beam-splitter and Mach-Zehnder interferometer experiments on a causal,
event-by-event basis and demonstrate that the simulation results are in
excellent agreement with quantum theory.Comment: EuroPhys. Lett. (in press); http://www.compphys.net/dl
Recent collisional jet from a primitive asteroid
Here we show an example of a young asteroid cluster located in a dynamically
stable region, which was produced by partial disruption of a primitive body
about 30 km in size. We estimate its age to be only 1.9 +/- 0.3 Myr, thus its
post-impact evolution should have been very limited. The large difference in
size between the largest object and the other cluster members means that this
was a cratering event. The parent body had a large orbital inclination, and was
subject to collisions with typical impact speeds higher by a factor of 2 than
in the most common situations encountered in the main belt. For the first time
we have at disposal the observable outcome of a very recent event to study
high-speed collisions involving primitive asteroids, providing very useful
constraints to numerical simulations of these events and to laboratory
experiments.Comment: Accepted for publication by MNRA
New method to simulate quantum interference using deterministic processes and application to event-based simulation of quantum computation
We demonstrate that networks of locally connected processing units with a
primitive learning capability exhibit behavior that is usually only attributed
to quantum systems. We describe networks that simulate single-photon
beam-splitter and Mach-Zehnder interferometer experiments on a causal,
event-by-event basis and demonstrate that the simulation results are in
excellent agreement with quantum theory. We also show that this approach can be
generalized to simulate universal quantum computers.Comment: J. Phys. Soc. Jpn. (in press) http://www.compphys.net/dl
Grounding the Lexical Semantics of Verbs in Visual Perception using Force Dynamics and Event Logic
This paper presents an implemented system for recognizing the occurrence of
events described by simple spatial-motion verbs in short image sequences. The
semantics of these verbs is specified with event-logic expressions that
describe changes in the state of force-dynamic relations between the
participants of the event. An efficient finite representation is introduced for
the infinite sets of intervals that occur when describing liquid and
semi-liquid events. Additionally, an efficient procedure using this
representation is presented for inferring occurrences of compound events,
described with event-logic expressions, from occurrences of primitive events.
Using force dynamics and event logic to specify the lexical semantics of events
allows the system to be more robust than prior systems based on motion profile
Slow dynamics in a primitive tetrahedral network model
We report extensive Monte Carlo and event-driven molecular dynamics
simulations of the fluid and liquid phase of a primitive model for silica
recently introduced by Ford, Auerbach and Monson [J. Chem. Phys. 17, 8415
(2004)]. We evaluate the iso-diffusivity lines in the temperature-density plane
to provide an indication of the shape of the glass transition line. Except for
large densities, arrest is driven by the onset of the tetrahedral bonding
pattern and the resulting dynamics is strong in the Angell's classification
scheme. We compare structural and dynamic properties with corresponding results
of two recently studied primitive models of network forming liquids -- a
primitive model for water and a angular-constraint free model of
four-coordinated particles -- to pin down the role of the geometric constraints
associated to the bonding. Eventually we discuss the similarities between
"glass" formation in network forming liquids and "gel" formation in colloidal
dispersions of patchy particles.Comment: 9 pages, 10 figure
Simulation of Quantum Computation: A deterministic event-based approach
We demonstrate that locally connected networks of machines that have
primitive learning capabilities can be used to perform a deterministic,
event-based simulation of quantum computation. We present simulation results
for basic quantum operations such as the Hadamard and the controlled-NOT gate,
and for seven-qubit quantum networks that implement Shor's numbering factoring
algorithm.Comment: J. Comp. Theor. Nanoscience (in press); http://www.compphys.net/dl
Circuit design tool. User's manual, revision 2
The CAM chip design was produced in a UNIX software environment using a design tool that supports definition of digital electronic modules, composition of these modules into higher level circuits, and event-driven simulation of these circuits. Our design tool provides an interface whose goals include straightforward but flexible primitive module definition and circuit composition, efficient simulation, and a debugging environment that facilitates design verification and alteration. The tool provides a set of primitive modules which can be composed into higher level circuits. Each module is a C-language subroutine that uses a set of interface protocols understood by the design tool. Primitives can be altered simply by recoding their C-code image; in addition new primitives can be added allowing higher level circuits to be described in C-code rather than as a composition of primitive modules--this feature can greatly enhance the speed of simulation
Water Delivery and Giant Impacts in the 'Grand Tack' Scenario
A new model for terrestrial planet formation (Hansen 2009, Walsh et al. 2011)
has explored accretion in a truncated protoplanetary disk, and found that such
a configuration is able to reproduce the distribution of mass among the planets
in the Solar System, especially the Earth/Mars mass ratio, which earlier
simulations have generally not been able to match. Walsh et al. tested a
possible mechanism to truncate the disk--a two-stage, inward-then-outward
migration of Jupiter and Saturn, as found in numerous hydrodynamical
simulations of giant planet formation. In addition to truncating the disk and
producing a more realistic Earth/Mars mass ratio, the migration of the giant
planets also populates the asteroid belt with two distinct populations of
bodies--the inner belt is filled by bodies originating inside of 3 AU, and the
outer belt is filled with bodies originating from between and beyond the giant
planets (which are hereafter referred to as `primitive' bodies).
We find here that the planets will accrete on order 1-2% of their total mass
from primitive planetesimals scattered onto planet-crossing orbits during the
formation of the planets. For an assumed value of 10% for the water mass
fraction of the primitive planetesimals, this model delivers a total amount of
water comparable to that estimated to be on the Earth today. While the radial
distribution of the planetary masses and the dynamical excitation of their
orbits are a good match to the observed system, we find that the last giant
impact is typically earlier than 20 Myr, and a substantial amount of mass is
accreted after that event. However, 5 of the 27 planets larger than half an
Earth mass formed in all simulations do experience large late impacts and
subsequent accretion consistent with the dating of the Moon-forming impact and
the estimated amount of mass accreted by Earth following that event
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