2,415 research outputs found
Geographic Centroid Routing for Vehicular Networks
A number of geolocation-based Delay Tolerant Networking (DTN) routing
protocols have been shown to perform well in selected simulation and mobility
scenarios. However, the suitability of these mechanisms for vehicular networks
utilizing widely-available inexpensive Global Positioning System (GPS) hardware
has not been evaluated. We propose a novel geolocation-based routing primitive
(Centroid Routing) that is resilient to the measurement errors commonly present
in low-cost GPS devices. Using this notion of Centroids, we construct two novel
routing protocols and evaluate their performance with respect to positional
errors as well as traditional DTN routing metrics. We show that they outperform
existing approaches by a significant margin.Comment: 6 page
Implementation of Epidemic Routing with IP Convergence Layer in ns-3
We present the Epidemic routing protocol implementation in ns-3. It is a
full-featured DTN protocol in that it supports the message abstraction and
store-and-haul behavior. We compare the performance of our Epidemic routing
ns-3 implementation with the existing implementation of Epidemic in the ONE
simulator, and discuss the differences
BEDROCK GEOLOGIC MAPPING AND STRUCTURAL ANALYSIS OF THE WESTERN HALF OF THE PETERSHAM QUADRANGLE, CENTRAL MASSACHUSETTS: FURTHER TESTS OF THE MODEL FOR MIDDLE TO LATE PALEOZOIC DUCTILE TRANSPRESSION, VERTICAL EXTRUSION, AND LATERAL ESCAPE IN THE NORTHERN APPALACHIANS
Bedrock mapping, structural analysis, and geochronology reveal the distribution of lithologies and timing of metamorphism and deformation in the western half of the Petersham 7.5’ quadrangle, western Massachusetts. Underlying lithologies are: (from west to east) the Ordovician Monson granitic orthogneiss, Silurian Rangeley migmatitic paragneiss, and Late Devonian (357 Ma) Hardwick tonalitic orthogneiss. Their tightly folded contacts strike north to south. The 361 Ma, unfoliated, strike-parallel Nichewaug quartz-diorite (10-100 m wide) intrusion spans the map area within the Rangeley. Evidence for vertical and lateral extrusion/escape of the Monson orthogneiss, as observed in the Palmer MA area, is absent. Instead, petrofabrics (foliations and lineations) indicate E-W shortening and N-S stretching concentrated within the Rangeley Fm. and orthogneiss margins. Asymmetric structures at the Rangeley-Hardwick contact indicate localized sinistral displacement parallel to unit boundaries and tectonic fabrics. U-Th-Pb chemical age dating of Rangeley monazite revealed three precise age populations (1 = 344 Ma; 3 = 377 Ma; 4 = 405 Ma) and one broad population divided into two subpopulations: 2b (~370 Ma) and 2a (~ 360 Ma). The similarity in age between tonalitic/dioritic magmatism and monazite growth in the Rangeley suggests regional metamorphism was driven by magmatic heat input from latest Devonian/earliest Carboniferous plutonism
End-to-End Resilience Mechanisms for Network Transport Protocols
The universal reliance on and hence the need for resilience in network communications has been well established. Current transport protocols are designed to provide fixed mechanisms for error remediation (if any), using techniques such as ARQ, and offer little or no adaptability to underlying network conditions, or to different sets of application requirements. The ubiquitous TCP transport protocol makes too many assumptions about underlying layers to provide resilient end-to-end service in all network scenarios, especially those which include significant heterogeneity. Additionally the properties of reliability, performability, availability, dependability, and survivability are not explicitly addressed in the design, so there is no support for resilience. This dissertation presents considerations which must be taken in designing new resilience mechanisms for future transport protocols to meet service requirements in the face of various attacks and challenges. The primary mechanisms addressed include diverse end-to-end paths, and multi-mode operation for changing network conditions
A Distributed Platform for High-Speed Active Network Topology Discovery
Sponsored Research ArticleNaval Postgraduate School Cyber Academic Grou
How specific is synchronous neuronal firing? : Poster presentation
Background Synchronous neuronal firing has been discussed as a potential neuronal code. For testing first, if synchronous firing exists, second if it is modulated by the behaviour, and third if it is not by chance, a large set of tools has been developed. However, to test whether synchronous neuronal firing is really involved in information processing one needs a direct comparison of the amount of synchronous firing for different factors like experimental or behavioural conditions. To this end we present an extended version of a previously published method NeuroXidence [1], which tests, based on a bi- and multivariate test design, whether the amount of synchronous firing above the chance level is different for different factors
Ab initio structure modeling of complex thin-film oxides: thermodynamical stability of TiC/thin-film alumina
We present an efficient and general method to identify promising candidate
configurations for thin-film oxides and to determine structural characteristics
of (metastable) thin-film structures using ab initio calculations. At the heart
of this method is the complexity of the oxide bulk structure, from which a
large number of thin films with structural building blocks, that is motifs,
from metastable bulk oxide systems can be extracted. These span a coarse but
well-defined network of initial configurations for which density functional
theory (DFT) calculations predict and implement dramatic atomic relaxations in
the corresponding, resulting thin-film candidates. The network of thin-film
candidates (for various film thicknesses and stoichiometries) can be ordered
according to their variation in ab initio total energy or in ab initio
equilibrium Gibbs free energy. Analysis of the relaxed atomic structures for
the most favored structures gives insight into the nature of stable and
metastable thin-film oxides. We investigate ultrathin alumina nucleated on TiC
as a model system to illustrate this method.Comment: Submitted to PRB; 16 pages, 11 figure
Effective C2 Comms to the Tactical Edge in Challenged, Disrupted, and Denied Environments
Native IP networks are ill-equipped to handle the communication challenges found in wireless comms environments, resulting in communications outages that degrade C2 data flow and subject the user to disconnection, timeouts, and repeated login requests. We counter these limitations by integrating DTN (Disruption-Tolerant Networking) technology into the IP network using software+hardware or software-only solutions as appropriate. This work evaluates the tradeoffs between the currently available DTN software implementations and seeks to identify the one with the highest technical readiness level, as well as any barriers to adoption that may be present. We find that no current implementation is fully ready, and that each have particular pros and cons to adoption.Naval Research ProgramPrepared for Topic Sponsor: Maj Jeffrey Sykes, USMC, HQMC Aviation; Research Sponsor HQMC Aviation; Research POC Name: Maj Scott CuomoN16-M343-
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