53,832 research outputs found
Scale-free topology optimization for software-defined wireless sensor networks: A cyber-physical system
Due to the limited resource and vulnerability in wireless sensor networks, maximizing the network lifetime and improving
network survivability have become the top priority problem in network topology optimization. This article presents
a wireless sensor networks topology optimization model based on complex network theory and cyber-physical systems
using software-defined wireless sensor network architecture. The multiple-factor-driven virtual force field and network
division–oriented particle swarm algorithm are introduced into the deployment strategy of super-node for the implementation
in wireless sensor networks topology initialization, which help to rationally allocate heterogeneous network
resources and balance the energy consumption in wireless sensor networks. Furthermore, the preferential attachment
scheme guided by corresponding priority of crucial sensors is added into scale-free structure for optimization in topology
evolution process and for protection of vulnerable nodes in wireless sensor networks. Software-defined wireless
sensor network–based functional architecture is adopted to optimize the network evolution rules and algorithm parameters
using information cognition and flow-table configure mode. The theoretical analysis and experimental results
demonstrate that the proposed wireless sensor networks topology optimization model possesses both the small-world
effect and the scale-free property, which can contribute to extend the lifetime of wireless sensor networks with energy
efficiency and improve the robustness of wireless sensor networks with structure invulnerability
A Scale-Free Topology Construction Model for Wireless Sensor Networks
A local-area and energy-efficient (LAEE) evolution model for wireless sensor
networks is proposed. The process of topology evolution is divided into two
phases. In the first phase, nodes are distributed randomly in a fixed region.
In the second phase, according to the spatial structure of wireless sensor
networks, topology evolution starts from the sink, grows with an
energy-efficient preferential attachment rule in the new node's local-area, and
stops until all nodes are connected into network. Both analysis and simulation
results show that the degree distribution of LAEE follows the power law. This
topology construction model has better tolerance against energy depletion or
random failure than other non-scale-free WSN topologies.Comment: 13pages, 3 figure
Performance tradeoffs of dynamically controlled grid-connected inverters in low inertia power systems
Implementing frequency response using grid-connected inverters is one of the
popular proposed alternatives to mitigate the dynamic degradation experienced
in low inertia power systems. However, such solution faces several challenges
as inverters do not intrinsically possess the natural response to power
fluctuations that synchronous generators have. Thus, to synthetically generate
this response, inverters need to take frequency measurements, which are usually
noisy, and subsequently make changes in the output power, which are therefore
delayed. This paper explores the system-wide performance tradeoffs that arise
when measurement noise, power disturbances, and delayed actions are considered
in the design of dynamic controllers for grid-connected inverters. Using a
recently proposed dynamic droop (iDroop) control for grid-connected inverters,
which is inspired by classical first order lead-lag compensation, we show that
the sets of parameters that result in highest noise attenuation, power
disturbance mitigation, and delay robustness do not necessarily have a common
intersection. In particular, lead compensation is desired in systems where
power disturbances are the predominant source of degradation, while lag
compensation is a better alternative when the system is dominated by delays or
frequency noise. Our analysis further shows that iDroop can outperform the
standard droop alternative in both joint noise and disturbance mitigation, and
delay robustness
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