pinecone/core-2020-05-10-deduplication huggingface dataset:
Distributed simultaneous task allocation and motion coordination of autonomous vehicles using a parallel computing cluster

Task allocation and motion coordination are the main factors that should be consi-dered in the coordination of multiple autonomous vehicles in material handling systems. Presently, these factors are handled in different stages, leading to a reduction in optimality and efficiency of the overall coordination. However, if these issues are solved simultaneously we can gain near optimal results. But, the simultaneous approach contains additional algorithmic complexities which increase computation time in the simulation environment. This work aims to reduce the computation time by adopting a parallel and distributed computation strategy for Simultaneous Task Allocation and Motion Coordination (STAMC). In the simulation experiments, each cluster node executes the motion coordination algorithm for each autonomous vehicle. This arrangement enables parallel computation of the expensive STAMC algorithm. Parallel and distributed computation is performed directly within the interpretive MATLAB environment. Results show the parallel and distributed approach provides sub-linear speedup compared to a single centralised computing node
An algorithm for surface growing from laser scan generated point clouts

n robot applications requiring interaction with a partially/unknown environment, mapping is of paramount importance. This paper presents an effective surface growing algorithm for map building based on laser scan generated point clouds. The algorithm directly converts a point cloud into a surface and normals form which sees a significant reduction in data size and is in a desirable format for planning the interaction with surfaces. It can be used in applications such as robotic cleaning, painting and welding
Spatial-temporal certification framework and extension of X.509 attribute certificate framework and SAML standard to support spatial-temporal certificates

Proceeding of: 4th European PKI Workshop: Theory and Practice, EuroPKI 2007, Palma de Mallorca, Spain, June 28-30, 2007The recent development of location-based services has originated a set of new security services that address their particular security problems. Spatial-temporal certification services are among these new services. They have as main goal the generation of evidences about an entity’s spatial-temporal information and, in general, their life-cycle support. Currently there is still a lack of a general framework for spatial-temporal certification services. In this work it is presented such a framework and an extension of the X.509 attribute certificate framework and the SAML standard to represent spatial-temporal certificates
Unbounded-error One-way Classical and Quantum Communication Complexity

This paper studies the gap between quantum one-way communication complexity
$Q(f)$ and its classical counterpart $C(f)$, under the {\em unbounded-error}
setting, i.e., it is enough that the success probability is strictly greater
than 1/2. It is proved that for {\em any} (total or partial) Boolean function
$f$, $Q(f)=\lceil C(f)/2 \rceil$, i.e., the former is always exactly one half
as large as the latter. The result has an application to obtaining (again an
exact) bound for the existence of $(m,n,p)$-QRAC which is the $n$-qubit random
access coding that can recover any one of $m$ original bits with success
probability $\geq p$. We can prove that $(m,n,>1/2)$-QRAC exists if and only if
$m\leq 2^{2n}-1$. Previously, only the construction of QRAC using one qubit,
the existence of $(O(n),n,>1/2)$-RAC, and the non-existence of
$(2^{2n},n,>1/2)$-QRAC were known.Comment: 9 pages. To appear in Proc. ICALP 200
Distributed Computing with Advice: Information Sensitivity of Graph Coloring

International audienceWe study the problem of the amount of information (advice) about a graph that must be given to its nodes in order to achieve fast distributed computations. The required size of the advice enables to measure the information sensitivity of a network problem. A problem is information sensitive if little advice is enough to solve the problem rapidly (i.e., much faster than in the absence of any advice), whereas it is information insensitive if it requires giving a lot of information to the nodes in order to ensure fast computation of the solution. In this paper, we study the information sensitivity of distributed graph coloring
Perfect Information Stochastic Priority Games

International audienceWe introduce stochastic priority games - a new class of perfect information stochastic games. These games can take two different, but equivalent, forms. In stopping priority games a play can be stopped by the environment after a finite number of stages, however, infinite plays are also possible. In discounted priority games only infinite plays are possible and the payoff is a linear combination of the classical discount payoff and of a limit payoff evaluating the performance at infinity. Shapley games and parity games are special extreme cases of priority games
A Novel Strategy For Multiagent Coalitions in a Dynamic Hostile World

One of the main underpinning of the multi-agent systems community is how and why autonomous agents should cooperate with one another. Several formal and computational models of cooperative work or coalition are currently developed and used within multi-agent systems research. The coalition facilitates the achievement of cooperation among different agents. In this paper, a mental construct called attitude is proposed and its significance in coalition formation in a dynamic fire world is discussed. It shows that coalitions explore the attitudes and behaviours that help agents to achieve goals that cannot be achieved alone or to maximize net group utility
An Analysis of the Hermes8 Stream Ciphers

Hermes8 [6,7] is one of the stream ciphers submitted to the ECRYPT Stream Cipher Project (eSTREAM [3]). In this paper we present an analysis of the Hermes8 stream ciphers. In particular, we show an attack on the latest version of the cipher (Hermes8F), which requires very few known keystream bytes and recovers the cipher secret key in less than a second on a normal PC. Furthermore, we make some remarks on the cipher's key schedule and discuss some properties of ciphers with similar algebraic structure to Hermes8
On the security of the LILI family of stream ciphers against algebraic attacks

In this paper, we present an algebraic analysis of the LILI family of stream ciphers, and in particular LILI-II, and investigate the security provided against both standard and fast algebraic attacks. We show that the size of the two registers used, the difference between their lengths, the maximum number of times a register is clocked and the degree of the filter function all play important roles in providing resistance against algebraic attacks. Further, we show that the degree 10 filter function used in LILI-II has an algebraic immunity (AI) of 4. Using this, a fast algebraic attack can be performed on LILI-II that significantly reduces the attack complexity, although not to such a degree that it is more efficient than exhaustive key search. These algebraic attacks recover the internal state of the cipher rather than the key bits. We investigate the role of the initialization process in providing resistance to algebraic attacks aimed at key recovery. The investigation shows that, generally, for the LILI family of stream ciphers, the complexity of recovering key bits using algebraic attacks is much worse than exhaustive key search because of the very high degree equations generated during the initialization process
Exchange bias effect of ferro-/antiferromagnetic heterostructures

The exchange bias (EB) effect was discovered 60 years ago by Meiklejohn and
Bean. Meanwhile the EB effect has become an integral part of modern magnetism
with implications for basic research and for numerous device applications. The
EB effect was the first of its kind which relates to an interface effect
between two different classes of materials, here between a ferromagnet and an
antiferromagnet. Here we review fundamental aspects of the exchange bias
effect.Comment: This contribution will be published as a book chapter in Springer
  :Tracts on Materials Science: "Magnetic Heterostructures, Advances and
  Perspectives in Spinstructures and Spintransport", edited by Hartmut Zabel
  and Samuel D. Bade
Towards Antihydrogen Confinement with the ALPHA Antihydrogen Trap

ALPHA is an international project that has recently begun experimentation at CERN's Antiproton Decelerator (AD) facility. The primary goal of ALPHA is stable trapping of cold antihydrogen atoms with the ultimate goal of precise spectroscopic comparisons with hydrogen. We discuss the status of the ALPHA project and the prospects for antihydrogen trapping.ALPHA is an international project that has recently begun experimentation at CERN's Antiproton Decelerator (AD) facility. The primary goal of ALPHA is stable trapping of cold antihydrogen atoms with the ultimate goal of precise spectroscopic comparisons with hydrogen. We discuss the status of the ALPHA project and the prospects for antihydrogen trapping
The Time-Energy Uncertainty Relation

The time energy uncertainty relation has been a controversial issue since the
advent of quantum theory, with respect to appropriate formalisation, validity
and possible meanings. A comprehensive account of the development of this
subject up to the 1980s is provided by a combination of the reviews of Jammer
(1974), Bauer and Mello (1978), and Busch (1990). More recent reviews are
concerned with different specific aspects of the subject. The purpose of this
chapter is to show that different types of time energy uncertainty relation can
indeed be deduced in specific contexts, but that there is no unique universal
relation that could stand on equal footing with the position-momentum
uncertainty relation. To this end, we will survey the various formulations of a
time energy uncertainty relation, with a brief assessment of their validity,
and along the way we will indicate some new developments that emerged since the
1990s.Comment: 33 pages, Latex. This expanded version (prepared for the 2nd edition
  of "Time in quantum mechanics") contains minor corrections, new examples and
  pointers to some additional relevant literatur
Heating and cooling in the Perseus cluster core

It is well known that the radiative cooling time of the hot X-ray emitting gas in the cores of most clusters of galaxies is less than 10^10 yr. In many clusters the gas temperature also drops towards the centre. If we draw a causal connection between these two properties then we infer the presence of a cooling flow onto the central galaxy. High spectral resolution XMM-Newton data and high spatial resolution Chandra data, show however a lack of X-ray emitting gas below about one third of the cluster virial temperature. The explanation is that some form of heating balances cooling. The smoothness and similarity of the cooling time profiles and the flatness of the required heating profiles all indicate that we must seek a relatively gentle, quasi-continuous (on timescales <10^8 yr), distributed heat source. The likely such source is the central black hole and its powerful jets which create bubble-like cavities in the inner hot gas. We briefly review the general heating and cooling statistics in an X-ray bright sample of cluster before we discuss the detailed situation in the Perseus cluster, the X-ray brightest cluster in the Sky
Hard X-ray emission from the core of the Perseus cluster and the thermal content of the radio bubbles

We use a very deep 900 ks Chandra X-ray observation of the core of the Perseus cluster to measure and confirm the hard X-ray emission detected from a previous analysis. By fitting a model made up of multiple temperature components plus a powerlaw or hot thermal component, we map the spatial distribution of the hard flux. We confirm there is a strong hard excess within the central regions. The total luminosity in the 2-10 keV band inside 3 arcmin radius is ~5x10^43 erg s^-1. As a second project we place limits on the thermal gas content of the X-ray cavities in the cluster core. This is done by fitting a model made up of multiple components to spectra from inside and outside of the bubbles, and looking at the the difference in strength of a component at a particular temperature. This approach avoids assumptions about the geometry of the core of the cluster. Only up to 50 per cent of the volume of the cavities can be filled with thermal gas with a temperature of 50 keV
Shock heating by nearby AGN

Shock heating by radio jets is potentially an important process in a range of environments, as it will increase the entropy of the heated gas. Although this process is expected to occur in the most powerful radio-loud AGN, strong shocks have so far only been detected in nearby low-power radio galaxies. Here we discuss X-ray detections of strong shocks in nearby galaxies, including a new detection of shocked gas around both lobes of the nearby radio galaxy NGC 3801 with inferred Mach numbers of 3 - 6 and a total injected energy comparable to the thermal energy of the ISM within 11 kpc. We discuss possible links between shock heating, AGN fuelling and galaxy mergers and the role of this type of system in feedback models
Radio Source Heating in the ICM: The Example of Cygnus A

One of the most promising solutions for the cooling flow problem involves
energy injection from the central AGN. However it is still not clear how
collimated jets can heat the ICM at large scale, and very little is known
concerning the effect of radio lobe expansion as they enter into pressure
equilibrium with the surrounding cluster gas. Cygnus A is one of the best
examples of a nearby powerful radio galaxy for which the synchrotron emitting
plasma and thermal emitting intra-cluster medium can be mapped in fine detail,
and previous observations have inferred possible shock structure at the
location of the cocoon. We use new XMM-Newton observations of Cygnus A, in
combination with deep Chandra observations, to measure the temperature of the
intra-cluster medium around the expanding radio cavities. We investigate how
inflation of the cavities may relate to shock heating of the intra-cluster gas,
and whether such a mechanism is sufficient to provide enough energy to offset
cooling to the extent observed.Comment: To appear in the Proceedings of "Heating vs. Cooling in Galaxies and
  Clusters of Galaxies", August 2006, Garching (Germany), Eds. H. Boehringer,
  G.W. Pratt, A. Finoguenov, P. Schuecker, Springer-Verlag series "ESO
  Astrophysics Symposia", p.101, in press. 8 pages, 3 multiple figure
Radio Properties of Cavities in the ICM: Imprints of AGN Activity

We present new, high resolution radio images of sources associated with cD galaxies and X-ray cavity systems located in cluster cores. The cavity properties derived from archival Chandra observations give reliable estimates of the total jet power and age independently of the radio synchrotron flux. We combine the X-ray data and VLA radio images taken at multiple frequencies to investigate several fundamental properties of cluster radio sources, including their radiative (mechanical) efficiencies, magnetic field contents, and particle contents, and we evaluate the assumption of equipartition in these systems. We show that high radio frequencies probe the current AGN output, while frequencies at or below 327 MHz trace the history of AGN activity in the cores of clusters over the past several hundred million years
The Growth of Black Holes and Bulges at the Cores of Cooling Flows

Central cluster galaxies (cDs) in cooling flows are growing rapidly through gas accretion and star formation. At the same time, AGN outbursts fueled by accretion onto supermassive black holes are generating X-ray cavity systems and driving outflows that exceed those in powerful quasars. We show that the resulting bulge and black hole growth follows a trend that is roughly consistent with the slope of the local (Magorrian) relation between bulge and black hole mass for nearby quiescent ellipticals. However, a large scatter suggests that cD bulges and black holes do not always grow in lock-step. New measurements made with XMM, Chandra, and FUSE of the condensation rates in cooling flows are now approaching or are comparable to the star formation rates, alleviating the need for an invisible sink of cold matter. We show that the remaining radiation losses can be offset by AGN outbursts in more than half of the systems in our sample, indicating that the level of cooling and star formation is regulated by AGN feedback
Radio Galaxies in Cooling Cores: Insights from a Complete Sample

We have observed a new, complete, cooling-core sample with the VLA, in order to understand how the massive black hole in the central galaxy interacts with the local cluster plasma. We find that every cooling core is currently being energized by an active radio jet, which has probably been destabilized by its interaction with the cooling core. We argue that current models of cooling-core radio galaxies need to be improved before they can be used to determine the rate at which the jet is heating the cooling core. We also argue that the extended radio haloes we see in many cooling-core clusters need extended, in situ re-energization, which cannot be supplied solely by the central galaxy
AGN Heating through Cavities and Shocks

Three comments are made on AGN heating of cooling flows. A simple physical argument is used to show that the enthalpy of a buoyant radio lobe is converted to heat in its wake. Thus, a significant part of ``cavity'' enthalpy is likely to end up as heat. Second, the properties of the repeated weak shocks in M87 are used to argue that they can plausibly prevent gas close to the AGN from cooling. As the most significant heating mechanism at work closest to the AGN, shock heating probably plays a critical role in the feedback mechanism. Third, results are presented from a survey of AGN heating rates in nearby giant elliptical galaxies. With inactive systems included, the overall AGN heating rate is reasonably well matched to the total cooling rate for the sample. Thus, intermittent AGN outbursts are energetically capable of preventing the hot atmospheres of these galaxies from cooling and forming stars
The lifecycle of powerful AGN outflows

During the course of this conference, much evidence was presented that points to an intimate connection between the energetic outflows driven by AGN and the energy budget and quite possibly also the evolution of their gaseous environments. However, it is still not clear if and how the AGN activity is triggered by the cooling gas, how long the activity lasts for and how these effects give rise to the observed distribution of morphologies of the outflows. In this contribution we concentrate on the high radio luminosity end of the AGN population. While most of the heating of the environmental gas may be due to less luminous and energetic outflows, these more powerful objects have a very profound influence on their surroundings. We will describe a simple model for powerful radio galaxies and radio-loud quasars that explains the dichotomy of their large-scale radio morphologies as well as their radio luminosity function
The role of AGN feedback and gas viscosity in hydrodynamical simulations of galaxy clusters

We study the imprints of AGN feedback and physical viscosity on the properties of galaxy clusters using hydrodynamical simulation models carried out with the TreeSPH code GADGET-2. Besides self-gravity of dark matter and baryons, our approach includes radiative cooling and heating processes of the gas component and a multiphase model for star formation and SNe feedback. Additionally, we introduce a prescription for physical viscosity in GADGET-2, based on a SPH discretization of the Navier-Stokes and general heat transfer equations. Adopting the Braginskii parameterization for the shear viscosity coefficient, we explore how gas viscosity influences the properties of AGN-driven bubbles. We also introduce a novel, self-consistent AGN feedback model where we simultaneously follow the growth and energy release of massive black holes embedded in a cluster environment. We assume that black holes accreting at low rates with respect to the Eddington limit are in a radiatively inefficient regime, and that most of the feedback energy will appear in a mechanical form. Thus, we introduce AGN-driven bubbles into the ICM with properties, such as radius and energy content, that are directly linked to the black hole physics. This model leads to a self-regulated mechanism for the black hole growth and overcomes the cooling flow problem in host halos, ranging from the scale of groups to that of massive clusters. (Abridged
Cold Feedback in Cooling-Flow Galaxy Clusters

We put forward an alternative view to the Bondi-driven feedback between heating and cooling of the intra-cluster medium (ICM) in cooling flow galaxies and clusters. We adopt the popular view that the heating is due to an active galactic nucleus (AGN), i.e. a central black hole accreting mass and launching jets and/or winds. We propose that the feedback occurs with the entire cool inner region (5-30 kpc). A moderate cooling flow does exist here, and non-linear over-dense blobs of gas cool fast and are removed from the ICM before experiencing the next major AGN heating event. Some of these blobs may not accrete on the central black hole, but may form stars and cold molecular clouds. We discuss the conditions under which the dense blobs may cool to low temperatures and feed the black hole
Entropy generation in merging galaxy clusters

In McCarthy et al. (2007, astro-ph/0701335) we present an analysis of entropy generation during cluster mergers, using SPH simulations. This conference proceeding contribution summarizes some of the most important findings of that paper, without all the technical details. Our main result is that during cluster mergers, entropy is generated in two major shock episodes, that heat the gas from the inside-out, in a way that distributes most of the energy within the more massive clump. This is different from the "onion-skin" model adopted in many simple analytic models of cluster formation
Cold fronts in cool core clusters

Cold fronts have been detected both in merging and in cool core clusters, where little or no sign of a merging event is present. A systematic search of sharp surface brightness discontinuities performed on a sample of 62 galaxy clusters observed with XMM-Newton shows that cold fronts are a common feature in galaxy clusters. Indeed most (if not all) of the nearby clusters (z < 0.04) host a cold front. Understanding the origin and the nature of a such frequent phenomenon is clearly important. To gain insight on the nature of cold fronts in cool core clusters we have undertaken a systematic study of all contact discontinuities detected in our sample, measuring surface brightness, temperature and when possible abundance profiles across the fronts. We measure the Mach numbers for the cold fronts finding values which range from 0.2 to 0.9; we also detect a discontinuities in the metal profile of some clusters