733,369 research outputs found
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Distributed H∞-consensus filtering for target state tracking over a wireless filter network with switching topology, channel fading and packet dropouts
No full textThis paper is concerned with the problem of distributed H∞-consensus filtering for target state tracking over a wireless filter network. The wireless filter network consists of a large number of filter nodes. The network topology is supposed to be switching or changeable over time. Data communication between filter nodes is subject to some network-induced constraints including packet dropouts and channel fading. Different from some existing results, packet dropouts and channel fading are assumed to occur not only in the measurement process for sensors but also in the transmission process among filter nodes. Within such settings, a distributed H∞-consensus filtering method is developed to ensure both the estimation accuracy of filters and the robustness of the filtering error system against network-induced constraints. Criteria on designing desired distributed H∞ consensus-based filter are derived in terms of a set of linear matrix inequalities. Numerical examples are given to verify the effectiveness of the proposed target state tracking filtering algorithm.Full Tex
Orthogonal Frequency Division Multiplex transmission of H.263 encoded video over wireless ATM networks
No full textThe video performance of the Median wireless asynchronous transfer mode (WATM) system is evaluated for a range of application scenarios using the H.263 video codec and a novel packetisation and acknowledgement scheme. The video resolutions and system parameters used are summarised in Tables 1 and 2. The required channel signal-to-noise ratio for near-unimpaired video quality is about 16dB over the dispersive worst-case channel used
AN EFFECTIVE OVERLAY H.263+VIDEO MULTICAST SYSTEM OVER THE INTERNET
No full textThis paper presents an effective overlay H.263+ video multicast system over the Internet. The proposed system consists of overlay multicast tree construction, target bandwidth determining process, and H.263+ rate control. Overlay multicast tree construction algorithm and target bandwidth determining process work alternatively to satisfy the average delay constraint, and H.263+ rate control is implemented to enhance the human visual perceptual quality over the multicast tree. Finally, experimental results are provided to show the performance of the proposed system.X11sciescopu
A survey of handover algorithms in DVB-H
No full textDigital Video Broadcasting for Handhelds (DVB-H) is a standard for
broadcasting IP Datacast (IPDC) services to mobile handheld terminals.
Based on the DVB-T standard, DVB-H adds new features such as time
slicing, MPE-FEC, in-depth interleavers, mandatory cell id identifier,
optional 4K-modulation mode and the use of 5 MHz bandwidth in addition
to the usually used 6, 7, or 8 MHz raster. IPDC over DVB-H is proposed
for ETSI to complement the DVB-H standard by combining IPDC and
DVB-H in an end-to-end system. Handover in such unidirectional broadcasting
networks is a novel issue. In the last few years since the birth of
DVB-H technology, great attention has been given to the performance
analysis of DVB-H mobile terminals. Handover is one of the main research
topics for DVB-H in mobile scenarios. Better reception quality and greater
power efficiency are considered to be the main targets of handover
research for DVB-H. New algorithms for different handover stages in
DVB-H have been the subject of recent research and are currently being
studied. Further novel algorithms need to be designed to improve the
mobile reception quality. This article provides a comprehensive survey of
the handover algorithms in DVB-H. A systematic evaluation and categorization
approach is proposed based on the problems the algorithms solve
and the handover stages being focused on. Criteria are proposed and analyzed
to facilitate designing better handover algorithms for DVB-H that
have been identified from the research conducted by the author
Contribution of Information and Communication Technology (ICT) in Country’S H-Index
No full textThe aim of this study is to examine the effect of Information and Communication Technology (ICT) development on country’s scientific ranking as measured by H-index. Moreover, this study applies ICT development sub-indices including ICT Use, ICT Access and ICT skill to find the distinct effect of these sub-indices on country’s H-index. To this purpose, required data for the panel of 14 Middle East countries over the period 1995 to 2009 is collected. Findings of the current study show that ICT development increases the H-index of the sample countries. The results also indicate that ICT Use and ICT Skill sub-indices positively contribute to higher H-index but the effect of ICT access on country’s H-index is not clear
Methods in taxonomy and biostratigraphy, and some note on chronostratigraphy: the Devonian-Carboniferous Boundary
No full textThe atomic geometry of the (2x2) phases of O and CO+O on Rh(111)
No full textThe local adsorption geometries of the (2 × 2)-1O, (2 × 2)-2O, (2 × 2)-(O + CO) and (2 × 2)-(O + 2CO) phases on the Rh(111) surface have been investigated by analysing low-energy electron diffraction (LEED) intensity data. In all cases, the oxygen atoms were found to occupy the threefold fee site and the topmost layer spacing d12 of Rh(111) was found to be expanded by about 3%. Additional experiments with disordered oxygen overlayers prepared at low adsorption temperatures show a monotonic increase of d12 with oxygen coverage. An O coverage of θO ≈ 0.1 already lifts the contraction of 0.02 Å of the clean surface. This finding is remarkable as for Ru(0001) a substantial expansion of the first layer spacing (≈ 3%) is observed only at very high O coverages, e.g. for the (1 × 1)-O structure. For the high-coverage Rh(111)-(2 × 2)-2O phase a honeycomb arrangement of the O atoms can clearly be ruled out. The (2 × 2)-2O has rather to be regarded as a (2 × 1)-1O phase. In the mixed (2 × 2)-(O + CO) overlayer the CO molecule occupies the on-top position which is also expected from a reduced back-donation of (substrate) electron charge density due to coadsorbed O atoms. The presence of CO molecules weakens the Rh-O bond. Altogether, the structural findings nicely reflect the competition of CO and O for electron charge density at the Rh(111) surface. In the (2 × 2)-(O + 2CO) phase 60% of available hcp sites and 100% of available on-top sites in the (2 × 2) unit cell are occupied
Conodonts across the Devonian/Carboniferous boundary: a review and implication for the redefinition of the boundary and a proposal for an updated conodont zonation
No full textThis paper is a contribution to the redefinition of the base of Carboniferous system. At present the criterion for the definition of the Devonian–Carboniferous boundary is the first occurrence of a conodont species. In order to evaluate the stratigraphic potential for new criteria for the definition of the Devonian–Carboniferous boundary, the distribution of conodont species of Bispathodus, Branmehla, Palmatolepis, Polygnathus, Protognathodus, Pseudopolygnathus and Siphonodella across the boundary is presented and discussed. An updated biozonation scheme across the boundary based on the First Appearance of Bispathodus ac. aculeatus, Bispathodus costatus, Bispathodus ultimus, Protognathodus kockeli, Siphonodella bransoni and Siphonodella duplicata is proposed, and it is suggested that the new criterion for the definition of the base of the Carboniferous system be the First Appearance Datum of Pr. kockeli or Si. bransoni
Portrait of Pembroke Patton
No full textA portrait of Pembroke M. “Pem” Patton (1871-1939), who farmed hops in Patton Valley near Cherry Grove, west of Gaston, Oregon. Pem Patton's parents were among the earliest white settlers to claim land in the area. This photograph was made in the studio of H. A. Crosley in Forest Grove, who was active from the late 1880s-1890s. This photograph probably dates to circa 1890.[Transcription of handwritten note on back:] Pembrok Patto
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