1,721,022 research outputs found
Evaluation of Kalman Filtering for Network Time Keeping
No full textSummarization: Time information is critical for a variety of
applications in distributed environments that facilitate pervasive
computing and communication. This work describes
and evaluates a novel Kalman filtering algorithm for endto-end
time synchronization between a client computer and
a server of “true” time [e.g., a Global Positioning System
(GPS) source] using messages transmitted over packetswitched
networks, such as the internet. The messages exchanged
have the network time protocol (NTP) format, and
the algorithm evaluated, is performed only at the client
side. The Kalman filtering algorithm is compared to two
other techniques widely used, based on linear programming
and statistical averaging, and the experiments involve independent
consecutive measurements (Gaussian case) or measurements
exhibiting long-range dependence (self-similar
case). Performance is evaluated according to the estimation
error of frequency offset and time offset between client
and server clock, the standard deviation of the estimates
and the number of packets used for a specific estimation.
The algorithms could exploit existing NTP infrastructure,
and a specific example is presented.Presented on: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Contro
24μ Watt 26m range batteryless backscatter sensors with FM remodulation and selection diversity
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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