44,325 research outputs found
TSEP: Threshold-sensitive Stable Election Protocol for WSNs
Wireless Sensor Networks (WSNs) are expected to find wide applicability and
increasing deployment in near future. In this paper, we propose a new protocol,
Threshold Sensitive Stable Election Protocol (TSEP), which is reactive protocol
using three levels of heterogeneity. Reactive networks, as opposed to proactive
networks, respond immediately to changes in relevant parameters of interest. We
evaluate performance of our protocol for a simple temperature sensing
application and compare results of protocol with some other protocols LEACH,
DEEC, SEP, ESEP and TEEN. And from simulation results it is observed that
protocol outperforms concerning life time of sensing nodes used.Comment: 10th IEEE International Conference on Frontiers of Information
Technology (FIT 12), 201
On Modeling Geometric Joint Sink Mobility with Delay-Tolerant Cluster-less Wireless Sensor Networks
Moving Sink (MS) in Wireless Sensor Networks (WSNs) has appeared as a
blessing because it collects data directly from the nodes where the concept of
relay nodes is becomes obsolete. There are, however, a few challenges to be
taken care of, like data delay tolerance and trajectory of MS which is NP-hard.
In our proposed scheme, we divide the square field in small squares. Middle
point of the partitioned area is the sojourn location of the sink, and nodes
around MS are in its transmission range, which send directly the sensed data in
a delay-tolerant fashion. Two sinks are moving simultaneously; one inside and
having four sojourn locations and other in outer trajectory having twelve
sojourn locations. Introduction of the joint mobility enhances network life and
ultimately throughput. As the MS comes under the NP-hard problem, we convert it
into a geometric problem and define it as, Geometric Sink Movement (GSM). A set
of linear programming equations has also been given in support of GSM which
prolongs network life time
Analyzing Delay in Wireless Multi-hop Heterogeneous Body Area Networks
With increase in ageing population, health care market keeps growing. There
is a need for monitoring of health issues. Wireless Body Area Network (WBAN)
consists of wireless sensors attached on or inside human body for monitoring
vital health related problems e.g, Electro Cardiogram (ECG), Electro
Encephalogram (EEG), ElectronyStagmography (ENG) etc. Due to life threatening
situations, timely sending of data is essential. For data to reach health care
center, there must be a proper way of sending data through reliable connection
and with minimum delay. In this paper transmission delay of different paths,
through which data is sent from sensor to health care center over heterogeneous
multi-hop wireless channel is analyzed. Data of medical related diseases is
sent through three different paths. In all three paths, data from sensors first
reaches ZigBee, which is the common link in all three paths. Wireless Local
Area Network (WLAN), Worldwide Interoperability for Microwave Access (WiMAX),
Universal Mobile Telecommunication System (UMTS) are connected with ZigBee.
Each network (WLAN, WiMAX, UMTS) is setup according to environmental
conditions, suitability of device and availability of structure for that
device. Data from these networks is sent to IP-Cloud, which is further
connected to health care center. Delay of data reaching each device is
calculated and represented graphically. Main aim of this paper is to calculate
delay of each link in each path over multi-hop wireless channel.Comment: arXiv admin note: substantial text overlap with arXiv:1208.240
HEER: Hybrid Energy Efficient Reactive Protocol for Wireless Sensor Networks
Wireless Sensor Networks (WSNs) consist of numerous sensors which send sensed
data to base station. Energy conservation is an important issue for sensor
nodes as they have limited power.Many routing protocols have been proposed
earlier for energy efficiency of both homogeneous and heterogeneous
environments. We can prolong our stability and network lifetime by reducing our
energy consumption. In this research paper, we propose a protocol designed for
the characteristics of a reactive homogeneous WSNs, HEER (Hybrid Energy
Efficient Reactive) protocol. In HEER, Cluster Head(CH) selection is based on
the ratio of residual energy of node and average energy of network. Moreover,
to conserve more energy, we introduce Hard Threshold (HT) and Soft Threshold
(ST). Finally, simulations show that our protocol has not only prolonged the
network lifetime but also significantly increased stability period.Comment: 2nd IEEE Saudi International Electronics, Communications and
Photonics Conference (SIECPC 13), 2013, Riyadh, Saudi Arabi
Room-temperature superparamagnetism due to giant magnetic anisotropy in Mo defected single-layer MoS
Room-temperature superparamagnetism due to a large magnetic anisotropy energy
(MAE) of a single atom magnet has always been a prerequisite for nanoscale
magnetic devices. Realization of two dimensional (2D) materials such as
single-layer (SL) MoS, has provided new platforms for exploring magnetic
effects, which is important for both fundamental research and for industrial
applications. Here, we use density functional theory (DFT) to show that the
antisite defect (Mo) in SL MoS is magnetic in nature with a
magnetic moment of of 2 and, remarkably, exhibits an
exceptionally large atomic scale
MAE of 500 meV. Our
calculations reveal that this giant anisotropy is the joint effect of strong
crystal field and significant spin-orbit coupling (SOC). In addition, the
magnetic moment can be tuned between 1 and 3 by varying
the Fermi energy , which can be achieved either by changing
the gate voltage or by chemical doping. We also show that MAE can be raised to
1 eV with n-type doping of the MoS:Mo sample. Our systematic
investigations deepen our understanding of spin-related phenomena in SL
MoS and could provide a route to nanoscale spintronic devices.Comment: 7 pages, 7 figure
On Energy Efficiency and Delay Minimization in Reactive Protocols in Wireless Multi-hop Networks
In Wireless Multi-hop Networks (WMhNs), routing protocols with energy
efficient and delay reduction techniques are needed to fulfill users demands.
In this paper, we present Linear Programming models (LP_models) to assess and
enhance reactive routing protocols. To practically examine constraints of
respective LP_models over reactive protocols, we select AODV, DSR and DYMO. It
is deduced from analytical simulations of LP_models in MATLAB that quick route
repair reduces routing latency and optimizations of retransmission attempts
results efficient energy utilization. To provide quick repair, we enhance AODV
and DSR. To practically examine the efficiency of enhanced protocols in
different scenarios of WMhNs, we conduct simulations using NS- 2. From
simulation results, enhanced DSR and AODV achieve efficient output by
optimizing routing latencies and routing load in terms of retransmission
attempts
Two-dimensional Fermionic Hong-Ou-Mandel Interference with Weyl Fermions
We propose a two-dimensional Hong-Ou-Mandel (HOM) type interference
experiment for Weyl fermions in graphene and 3D topological insulators. Since
Weyl fermions exhibit linear dispersion, similar to photons in vacuum, they can
be used to obtain the HOM interference intensity pattern as a function of the
delay time between two Weyl fermions. We show that while the Coulomb
interaction leads to a significant change in the angle dependence of the
tunneling of two identical Weyl fermions incident from opposite sides of a
potential barrier, it does not affect the HOM interference pattern, in contrast
to previous expectations. We apply our formalism to develop a Weyl fermion
beam-splitter (BS) for controlling the transmission and reflection
coefficients. We calculate the resulting time-resolved correlation function for
two identical Weyl fermions scattering off the BS.Comment: 4 pages, 3 figure
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