444 research outputs found

    Vibration testing of a steel girder bridge using cabled and wireless sensors

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    Author's manuscript. The final publication is available at Springer via http://dx.doi.org/10.1007/s11709-011-0113-y© Higher Education Press and Springer-Verlag Berlin Heidelberg 2011Being able to significantly reduce system installation time and cost, wireless sensing technology has attracted much interest in the structural health monitoring (SHM) community. This paper reports the field application of a wireless sensing system on a 4-span highway bridge located in Wayne, New Jersey in the US. Bridge vibration due to traffic and ambient excitation is measured. To enhance the signal-to-noise ratio, a low-noise high-gain signal conditioning module is developed for the wireless sensing system. Nineteen wireless and nineteen cabled accelerometers are first installed along the sidewalk of two neighboring bridge spans. The performance of the wireless sensing system is compared with the high-precision cabled sensing system. In the next series of testing, sixteen wireless accelerometers are installed under the deck of another bridge span, forming a 4 × 4 array. Operating deflection analysis is successfully conducted using the wireless measurement of traffic and ambient vibrations.National Science Foundatio

    Absence of a transport signature of spin-orbit coupling in graphene with indium adatoms

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    Enhancement of the spin-orbit coupling in graphene may lead to various topological phenomena and also find applications in spintronics. Adatom absorption has been proposed as an effective way to achieve the goal. In particular, great hope has been held for indium in strengthening the spin-orbit coupling and realizing the quantum spin Hall effect. To search for evidence of the spin-orbit coupling in graphene absorbed with indium adatoms, we carry out extensive transport measurements, i.e., weak localization magnetoresistance, quantum Hall effect and non-local spin Hall effect. No signature of the spin-orbit coupling is found. Possible explanations are discussed.Comment: 5 pages, 4 figures, with supplementary material

    PREDICTION OF PEER-TO-PEER ROUTING REQUEST BASED ON LOW-POWER AND LOSSY NETWORKS BEHAVIOR ANALYTICS

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    Techniques are provided to predict Peer-to-Peer (P2P) routing requests in Low-Power and Lossy Networks (LLNs). With this prediction, a P2P routing path may be prepared on demand and in advance

    SWIFT NODE MIGRATION MECHANISMS FOR LOW POWER AND LOSSY NETWORKS

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    Techniques are described herein to refine Personal Area Network (PAN) migration processes and shorten offline duration using various mechanisms, including: 1) performing a re-authentication and key exchange with a target PAN\u27s Field Area Router (FAR) over a current PAN\u27s FAR while performing migration between the two PANs; 2) eliminating a re-authentication process by sharing the same pairwise master key (PMK) for one node between all FARs in one service set; 3) synchronizing with a target PAN over current PAN\u27s FAR, which can be quicker than synchronization over the air; and 4) eliminating Dynamic Host Configuration Protocol (DHCP) version 6 (DHCPv6) processes, keep a global Internet Protocol version 6 (IPv6) address unchanged, and creating a downward route adaptively while performing migration between the two PANs. Using these mechanisms, a node will be able to migrate between various PANs more quickly and the service interruption gap will be much shorter

    DYNAMIC OPTIMAL DATA COLLECTION BY GREEDY ALGORITHM IN LOW POWER AND LOSSY NETWORKS

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    Techniques are described herein for an executable greedy algorithm of data collection to produce an optimal strategy which may decrease congestion of packets and increase overall efficiency. This may be used to divide Low power and Lossy Network (LLN) nodes into groups and arrange the regular report schedule for all the nodes. First, the Routing Protocol for LLN (RPL) tree may be pulled from a router and the topology matrix generated. Second, the constraint condition of data transmission may be listed according to network transmission characteristics. Third, the state transition equation may be solved and an optimal schedule selected. Fourth, the schedule may be implemented with a Head-End System (HES)

    IMPROVING DETERMINISM FOR WIRELESS: SETTING DYNAMIC CLEAR CHANNEL ASSESSMENT THRESHOLD IN LOW-POWER AND LOSSY NETWORKS

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    Techniques are described herein for a mechanism to determine Clear Channel Assessment (CCA) thresholds in the scope of link neighbors in low power and lossy wireless networks. Without adding too much extra traffic, a dynamic, newly designed CCA threshold is unique for each link neighbor and helps to improve the wireless network performance

    SPIRAL DATA REPORTING MECHANISM IN LOW-POWER AND LOSSY NETWORKS

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    The embodiments presented herein relate to low-power and lossy networks (LLNs), and more specifically, to dividing LLN nodes into groups. Groups may be determined by traversing a directed acyclic graph (DAG) topology in a spiral manner. In this manner, contention, collisions, and interference may be minimized, while bandwidth usage can be maximized

    PROACTIVE METHOD FOR FASTER REFORMATION IN LOW-POWER AND LOSSY NETWORKS

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    Techniques are described herein for a proactive method to achieve faster reformation in Lower-power and Lossy Networks (LLNs). These techniques also provide reduced asynchronization and functions regardless of the number of powered-off nodes in the LLN

    INDUSTRIAL IOT/SMART MANUFACTURING: A HARDWARE APPROACH TO DISCOVER LINK NEIGHBOR IN LOW-POWER AND LOSSY NETWORKS

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    Techniques are provided, using a custom hardware block, to maintain a precise timestamp in restart or a power outage situation in a straightforward, cost effective manner. For connected grid mesh networks (CG-MESHs), when an entity needs to reform the network, the present techniques significantly reduce the cost of discovering a Personal Area Network (PAN) and reduce the frequency of asynchronous transmission. As a result, the performance of CG-MESH is improved
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