The IEEE 802.15.4 standard has attracted time-critical applications in wireless sensor networks (WSNs) because of its beaconenabled mode and guaranteed time slots (GTSs). However, the GTS management scheme’s built-in security mechanisms still leave the 802.15.4 MAC vulnerable to attacks. Further, the existing techniques in the literature for securing 802.15.4 either focus on non beacon-enabled ...

This paper deals with IEEE 802.15.4 beacon enabled and non beacon enabled multi-hop star wireless sensor networks with varying traffic loads. For high channel utilization & low power consumption, impact of MAC parameters such as beacon order (BO) and superframe order (SO) has been analyzed. IEEE 802.1.5.4 MAC works in two modes, beacon and non beacon mode. This paper provides the performance an...

A beacon is a point-like object that can be enabled to exert a magnetic pull on other point-like objects in space. Those objects then move towards the beacon in a greedy fashion until they are either stuck at an obstacle or reach the beacon’s location. Beacons placed inside polyhedra can be used to route point-like objects from one location to another. The notion of beacon-based routing was int...

PROBLEM Every year numerous occupational fatalities result from pedestrians being struck by motor vehicles intruding into work zones. METHOD Attributes of retroreflective personal safety garments on pedestrian conspicuity at night were assessed in a field study. Using instrumented vehicles on a closed track, participants drove through simulated work zones attempting to detect pedestrians loca...

This paper proposes novel algorithms for synchronizations and time resolution improvements of One Way Propagation Time (OWPT) measurement in the 802.11 Wireless Local Area Network (WLAN). In OWPT measurement, the Mobile Station (MS) records each 802.11 Beacon frame’s arrival time. The Beacon frame’s arrival time minus its Timestamp, which is recorded when the Beacon frame is transmitted from an...

We report a decentralized, vehicle-based extended information filter designed to enable single-beacon acoustic navigation of multiple underwater vehicles. In single-beacon navigation, ranges from a single reference beacon to a moving underwater vehicle are used in addition to the vehicle’s inertial navigation sensors to perform absolute (as opposed to relative) localization and navigation. For ...

In the past, there has been a tremendous progress in the area of autonomous robot navigation and a large variety of robots have been developed who demonstrated robust navigation capabilities indoors, in non-urban outdoor environments, or on roads and relatively few approaches focus on navigation in urban environments such as city centers. Urban areas, however, introduce numerous challenges for ...

Many insects have an innate propensity to approach conspicuous objects. We explore how such beacon aiming determines the shape of a wood ant's habitual route. We find that a single large black cylinder within an arena biases the route taken by ants as they run from a start position at one end of the arena to reach a feeder at the other. Ants learn a stable route with the first segment of their ...

Acmella uliginosa, Ceratotheca sesamoides, Justicia tenella and Sesamum radiatum are four traditional leafy vegetables which are widely consumed in Benin. In order to document their origin, folk nomenclature, geographical distribution and ecology and to select adequate zones for in situ conservation of their genetic resources, 118 villages were randomly selected and surveyed throughout the coun...

Singhbhum Shear Zone is a highly mineralized zone having variety of minerals, predominantly those of uranium, copper and some sulphide minerals. From Remote Sensing data it is possible to decipher the regional lithology, tectonic fabric and also the geomorphic details of a terrain which aid precisely in targeting of metals and minerals. Mapping of mineralized zones can be done using Geospatial ...