4,425 research outputs found
The ART of IAM: The Winning Strategy for the 2006 Competition
In many dynamic open systems, agents have to interact with one another to achieve their goals. Here, agents may be self-interested, and when trusted to perform an action for others, may betray that trust by not performing the actions as required. In addition, due to the size of such systems, agents will often interact with other agents with which they have little or no past experience. This situation has led to the development of a number of trust and reputation models, which aim to facilitate an agent's decision making in the face of uncertainty regarding the behaviour of its peers. However, these multifarious models employ a variety of different representations of trust between agents, and measure performance in many different ways. This has made it hard to adequately evaluate the relative properties of different models, raising the need for a common platform on which to compare competing mechanisms. To this end, the ART Testbed Competition has been proposed, in which agents using different trust models compete against each other to provide services in an open marketplace. In this paper, we present the winning strategy for this competition in 2006, provide an analysis of the factors that led to this success, and discuss lessons learnt from the competition about issues of trust in multiagent systems in general. Our strategy, IAM, is Intelligent (using statistical models for opponent modelling), Abstemious (spending its money parsimoniously based on its trust model) and Moral (providing fair and honest feedback to those that request it)
Spitzer 70 Micron Source Counts in GOODS-North
We present ultradeep Spitzer 70 μm observations of GOODS-North (Great Observatories Origins Deep Survey). For the first time, the turnover in the 70 μm Euclidean-normalized differential source counts is observed. We derive source counts down to a flux density of 1.2 mJy. From the measured source counts and fluctuation analysis, we estimate a power-law approximation of the faint 70 μm source counts of dN/dS ∝ S^−1.6, consistent with that observed for the faint 24 μm sources. An extrapolation of the 70 μm source counts to zero flux density implies a total extragalactic background light (EBL) of 7.4 ± 1.9 nW m^−2 sr^−1. The source counts above 1.2 mJy account for about 60% of the estimated EBL. From fluctuation analysis, we derive a photometric confusion level of σc = 0.30 ± 0.15 mJy (q = 5) for the Spitzer 70 μm band
The Spitzer Archival Far-InfraRed Extragalactic Survey
We present the Spitzer Archival Far-InfraRed Extragalactic Survey (SAFIRES).
This program produces refined mosaics and source lists for all far-infrared
extragalactic data taken during the more than six years of the cryogenic
operation of the Spitzer Space Telescope. The SAFIRES products consist of
far-infrared data in two wavelength bands (70 um and 160 um) across
approximately 180 square degrees of sky, with source lists containing
far-infrared fluxes for almost 40,000 extragalactic point sources. Thus,
SAFIRES provides a large, robust archival far-infrared data set suitable for
many scientific goals.Comment: 7 pages, 6 figures, published in ApJ
Spitzer 70 and 160-micron Observations of the COSMOS Field
We present Spitzer 70 and 160 micron observations of the COSMOS Spitzer
survey (S-COSMOS). The data processing techniques are discussed for the
publicly released products consisting of images and source catalogs. We present
accurate 70 and 160 micron source counts of the COSMOS field and find
reasonable agreement with measurements in other fields and with model
predictions. The previously reported counts for GOODS-North and the
extragalactic First Look Survey are updated with the latest calibration, and
counts are measured based on the large area SWIRE survey to constrain the
bright source counts. We measure an extragalactic confusion noise level of
sigma_c = 9.4+/-3.3 mJy (q=5) for the MIPS 160-micron band based on the deep
S-COSMOS data and report an updated confusion noise level of sigma_c =
0.35+/-0.15 mJy (q=5) for the MIPS 70-micron band.Comment: Accepted AJ, 15 Aug. 2009. Data available at
http://spider.ipac.caltech.edu/staff/frayer/mycosmos/ until released by IRS
Facile Solution Route to Synthesize Nanostructure Li 4
High rate Li-ion batteries have been given great attention during the last decade as a power source for hybrid electric vehicles (HEVs, EVs, etc.) due to the highest energy and power density. These lithium batteries required a new design of material structure as well as innovative electrode materials. Among the promising candidates, spinel Li4Ti5O12 has been proposed as a high rate anode to replace graphite anode because of high capacity and a negligible structure change during intercalation of lithium. In this work, we synthesized a spinel Li4Ti5O12 in nanosize by a solution route using LiOH and Ti(OBu)4 as precursor. An evaluation of structure and morphology by XRD and SEM exhibited pure spinel phase Li4Ti5O12 and homogenous nanoparticles around 100 nm. In the charge-discharge test, nanospinel Li4Ti5O12 presents excellent discharge capacity 160 mAh/g at rate C/10, as well as good specific capacities of 120, 110, and 100 mAh/g at high rates C, 5C and 10C, respectively
Facile Solution Route to Synthesize Nanostructure Li 4 Ti 5 O 12 for High Rate Li-Ion Battery
High rate Li-ion batteries have been given great attention during the last decade as a power source for hybrid electric vehicles (HEVs, EVs, etc.) due to the highest energy and power density. These lithium batteries required a new design of material structure as well as innovative electrode materials. Among the promising candidates, spinel Li 4 Ti 5 O 12 has been proposed as a high rate anode to replace graphite anode because of high capacity and a negligible structure change during intercalation of lithium. In this work, we synthesized a spinel Li 4 Ti 5 O 12 in nanosize by a solution route using LiOH and Ti(OBu) 4 as precursor. An evaluation of structure and morphology by XRD and SEM exhibited pure spinel phase Li 4 Ti 5 O 12 and homogenous nanoparticles around 100 nm. In the charge-discharge test, nanospinel Li 4 Ti 5 O 12 presents excellent discharge capacity 160 mAh/g at rate C/10, as well as good specific capacities of 120, 110, and 100 mAh/g at high rates C, 5C and 10C, respectively
Size dependent tunneling and optical spectroscopy of CdSe quantum rods
Photoluminescence excitation spectroscopy and scanning tunneling spectroscopy
are used to study the electronic states in CdSe quantum rods that manifest a
transition from a zero dimensional to a one dimensional quantum confined
structure. Both optical and tunneling spectra show that the level structure
depends primarily on the rod diameter and not on length. With increasing
diameter, the band-gap and the excited state level spacings shift to the red.
The level structure was assigned using a multi-band effective-mass model,
showing a similar dependence on rod dimensions.Comment: Accepted to PRL (nearly final version). 4 pages in revtex, 4 figure
A Two-Step Certified Reduced Basis Method
In this paper we introduce a two-step Certified Reduced Basis (RB) method. In the first step we construct from an expensive finite element “truth” discretization of dimension N an intermediate RB model of dimension N≪N . In the second step we construct from this intermediate RB model a derived RB (DRB) model of dimension M≤N. The construction of the DRB model is effected at cost O(N) and in particular at cost independent of N ; subsequent evaluation of the DRB model may then be effected at cost O(M) . The DRB model comprises both the DRB output and a rigorous a posteriori error bound for the error in the DRB output with respect to the truth discretization.
The new approach is of particular interest in two contexts: focus calculations and hp-RB approximations. In the former the new approach serves to reduce online cost, M≪N: the DRB model is restricted to a slice or subregion of a larger parameter domain associated with the intermediate RB model. In the latter the new approach enlarges the class of problems amenable to hp-RB treatment by a significant reduction in offline (precomputation) cost: in the development of the hp parameter domain partition and associated “local” (now derived) RB models the finite element truth is replaced by the intermediate RB model. We present numerical results to illustrate the new approach.United States. Air Force Office of Scientific Research (AFOSR Grant number FA9550-07-1-0425)United States. Department of Defense. Office of the Secretary of Defense (OSD/AFOSR Grant number FA9550-09-1-0613)Norwegian University of Science and Technolog
Radio Observations of the Hubble Deep Field South region: I. Survey Description and Initial Results
This paper is the first of a series describing the results of the Australia
Telescope Hubble Deep Field South (ATHDFS) radio survey. The survey was
conducted at four wavelengths - 20, 11, 6, and 3 cm, over a 4-year period, and
achieves an rms sensitivity of about 10 microJy at each wavelength. We describe
the observations and data reduction processes, and present data on radio
sources close to the centre of the HDF-S. We discuss in detail the properties
of a subset of these sources. The sources include both starburst galaxies and
galaxies powered by an active galactic nucleus, and range in redshift from 0.1
to 2.2. Some of them are characterised by unusually high radio-to-optical
luminosities, presumably caused by dust extinction.Comment: Accepted by AJ. 32 pages, 4 tables, 3 figures. PDF with
full-resolution figures is on
http://www.atnf.csiro.au/people/rnorris/N197.pd
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