Uncontrolled Node Research Articles

Fixed-time synchronization of delayed BAM neural networks via new fixed-time stability results and non-chattering quantized controls

In this paper, in order to obtain a smaller estimation of settling time, reduce chattering caused by sign function and improve network communication efficiency, the fixed-time (FXT) synchronization of delayed BAM neural networks is analyzed based on some new FXT stability results and non-chattering quantized controllers. Firstly, by comprehensively discussing the conditions of power laws in differential inequalities, a new FXT stability lemma is presented and a smaller upper bound of settling time is estimated. Then, unlike previous controllers with sign functions, a non-chattering quantized state feedback control and a non-chattering quantized pinning control are designed, and some sufficient conditions are derived to ensure FXT synchronization of the established system. Finally, two numerical simulations are given to verify the effectiveness of the theoretical results. The results show that compared with the previous researches, this paper provides a smaller upper bound. However, the convergence time of the uncontrolled nodes is indirectly affected by the coupling of the controlled nodes and is much longer than the estimated upper bound.

Target control of complex networks: How to save control energy.

Controlling complex networks has received much attention in the past two decades. In order to control complex networks in practice, recent progress is mainly focused on the control energy required to drive the associated system from an initial state to any final state within finite time. However, one of the major challenges when controlling complex networks is that the amount of control energy is usually prohibitively expensive. Previous explorations on reducing the control energy often rely on adding more driver nodes to be controlled directly by external control inputs, or reducing the number of target nodes required to be controlled. Here we show that the required control energy can be reduced exponentially by appropriately setting the initial states of uncontrollable nodes for achieving the target control of complex networks. We further present the energy-optimal initial states and theoretically prove their existence for any structure of network. Moreover, we demonstrate that the control energy could be saved by reducing the distance between the energy-optimal states set and the initial states of uncontrollable nodes. Finally, we propose a strategy to determine the optimal time to inject the control inputs, which may reduce the control energy exponentially. Our conclusions are all verified numerically, and shed light on saving control energy in practical control.

Effect of the interdependence between subnets on the structural controllability of complex networks

AbstractControllability is a hot issue in complex networks. In this paper, without changing the number and the positions of the controllers, the effect of interdependence (viz., inter‐coupling relations) between two directed subnets that are controllable or uncontrollable on the structural controllability of complex networks is investigated. According to the Kalman rank criterion and PBH rank criterion, some sufficient conditions and necessary conditions for the structural controllability or uncontrollability of interdependent networks are presented. The results show that (1) if the uncontrollable and controllable nodes in one subnet are inter‐coupled with the controllable and uncontrollable nodes in the other subnet, respectively, and the directions are from controllable nodes to the uncontrollable nodes, then the interdependent network may be controllable; (2) the interdependent network can be obtained structurally controllable if there are simply directed paths covering all the uncontrollable nodes of the two subnets, separately; and (3) the interdependent networks are structurally controllable no matter what kind of inter‐couplings between two controllable subnets. All of these results are adaptive to undirected subnets. The final example verifies the effectiveness and correctness of the results provided in this paper.

Optimal Control for Networks with Unobservable MaliciousNodes

With the rapid development of information technology, modern network systems are becoming increasingly complex and are increasingly vulnerable to attacks such as Distributed Denial-of-Service (DDoS) attack. However, existing network control algorithms either require full observability and/or controllability for all nodes [2, 9, 1, 4, 6], or the network dynamics to be time-invariant and stochastic [7, 3, 8, 5]. In this paper, we aim to develop a new algorithm that can stabilize networks with unobservable and uncontrollable nodes under adversarial dynamics (i.e., external arrivals and actions of malicious nodes).

Complex Network Controllability Analysis on Business Architecture Optimization

Currently, the business process elements in the design of organizational business architecture are becoming increasingly complex, showing trends of networking and flattening. The control of complex business processes is a key factor for business architecture design. This paper considers a complex network generation method with business process and organization structure data and analyzes complex network controllability to examine the alignment of business processes and the organization structure. The uncontrollable nodes of the complex network can be identified, which act as the input for organization structure adjustment and business architecture optimization design.

Optimizing Pinning Control of Complex Dynamical Networks Based on Spectral Properties of Grounded Laplacian Matrices

Pinning control of a complex network aims at forcing the states of all nodes to track an external signal by controlling a small number of nodes in the network. In this paper, an algebraic graph-theoretic condition is introduced to optimize pinning control. When individual node dynamics and coupling strength of the network are given, the effectiveness of pinning scheme can be measured by the smallest eigenvalue of the grounded Laplacian matrix obtained by deleting the rows and columns corresponding to the pinned nodes from the Laplacian matrix of the network. The larger this smallest eigenvalue, the more effective the pinning scheme. Spectral properties of the smallest eigenvalue are analyzed using the network topology information, including the spectrum of the network Laplacian matrix, the minimal degree of uncontrolled nodes, the number of edges between the controlled node set and the uncontrolled node set, etc. The identified properties are shown effective for optimizing the pinning control strategy, as demonstrated by illustrative examples. Finally, for both scale-free and small-world networks, in order to maximize their corresponding smallest eigenvalues, it is better to pin the nodes with large degrees when the percentage of pinned nodes is relatively small, while it is better to pin nodes with small degrees when the percentage is relatively large. This surprising phenomenon can be explained by one of the theorems established.

Design of an Optimal Distributed Energy Efficient Hybrid Optical – Acoustic Cluster Based Routing Protocol (EEHCRP) to Minimize the Energy Consumption in Underwater Wireless Sensor Networks

For ocean exploration high speed data transmission is the emergent requirement. Acoustic sensor networks are available to support large distances but with lower data rates and also consume maximum energy. Optical networks can be used to support high speed data transmission but it cannot be used for larger distances. Underwater Wireless Sensor Networks (UWSN) suffer from large propagation delay, high bit error rates, limited bandwidth, uncontrolled node mobility, water current and limited resources. Hence there is an evolving requirement for design and use of an efficient routing protocol. In the proposed research, design of an Optimal Distributed Energy Efficient Hybrid Optical - Acoustic Cluster Based Routing Protocol (EEHCRP) to minimize the energy consumption in Underwater Wireless Sensor Networks is considered. To overcome these problems we propose an Energy Efficient Hybrid Optical-Acoustic Cluster Based Routing Protocol for Underwater Wireless Sensor Network (EEHCRP). In this research work we study various network parameters like network throughput, network life time, average energy consumption, end to end delay and data delivery ratio for mobile nodes ranging from 50 to 500. It is observed that there is an average increase of 0.9% network throughput in the proposed EEHRCP protocol compared to CBE2R protocol. The network life time is increased to 51.2 seconds with a decrease in 0.93% of energy consumption and 0.48 % decrease in end to end delay in the proposed protocol EEHRCP compared to CBE2R protocol. There is an increase in 0.95% of data delivery ratio using the proposed EEHRCP protocol compared to E-CBCCP protocol.

Finite-time synchronisation control of coupled reaction-diffusion systems

ABSTRACTWe consider the finite-time synchronisation for coupled reaction-diffusion systems. At first, we design a pinning control strategy for the coupled systems. For the uncontrolled nodes, we use the adaptive adjustment to the coupling strength. Based on the Poincaré inequality technique and using the finite-time stability lemma, we obtain the sufficient condition to ensure the finite-time synchronisation. Time delay occurs usually in the coupled systems and when there exist time-varying delays in the coupled reaction-diffusion systems, we design a controller to impel the coupled systems to achieve the finite-time synchronisation. Finally, numerical examples are given to illustrate our theoretical results.

Synchronization of Time-Delayed Complex Networks With Switching Topology Via Hybrid Actuator Fault and Impulsive Effects Control.

This article investigates global exponential synchronization almost surely (GES a.s.) of complex networks (CNs) with node delay and switching topology. By introducing transition probability (TP) and mode-dependent average dwell time (MDADT) to the switching signal, the considered model is more practical than the systems with average dwell-time (ADT) switching. Controllers with both impulsive effects and actuator fault feedback are considered. New analytical techniques are developed to obtain sufficient conditions to guarantee the GES a.s. Different from the existing results on the synchronization of switched systems, our results show that the GES a.s. can still be achieved even in the case that the upper bound of the dwell time (DT) of uncontrolled nodes is very large and the lower bound of the DT of controlled nodes is very small. Numerical examples demonstrate the effectiveness and the merits of the theoretical analysis.

M2DFR: Multi-layer Multipath Data Forwarding Routing Protocol for Underwater Wireless Sensor Network

Objectives: To design and develop the Multi-layer Multipath Data Forwarding Routing (M2DFR) protocol for Underwater Wireless Sensor Network which controls the water depth, node mobility and can enhance the overall performance. Method/Analysis: M2DFR is based on three phases, one is design of architecture under which the deployment of the nodes are shown, second is the initialization phase which develops the multipath route selection mechanism between seabed source nodes to ordinary nodes which are deployed in the lower depth to upper layer, Acoustic Powerful Nodes (APNs) deployed in upper depth in fixed way in layers to surface sink nodes which are deployed on water surface, the route selection for multipath is based on RREQ/RREP through Weight Calculation Mechanism (WCM). Third phase focuses the data forwarding phase under which the shortest WCM is selected and from this route packets are forwarded from source nodes to sink nodes. Findings: Most of the existing protocols are unable to overcome the problem of water depth controlling, uncontrolled node mobility. Applications/Improvements: M2DFR is designed to extract the information from the bottom of the sea with its applications like: gold, oil/gas and minerals. The improved performance of M2DFR is measured with CBE2R and EMGGR. Keywords: APNs, Higher-Depth, Lower-Depth, Node-Mobility, WCM

CBE2R: clustered-based energy efficient routing protocol for underwater wireless sensor network

ABSTRACTRouting in undersea environment is one of the challenging research areas due to the nature of acoustic channel and underwater harsh environment. In underwater environment, the major challenges are propagation delay, high bit error rates, limited bandwidth, uncontrolled node mobility, water current, 3D deployment and limited resources. Hence, designing an efficient and communication protocols for underwater environment is a challenging issue. To control the node mobility and prolong the battery power of the nodes, we proposed Clustered-Based Energy Efficient Routing (CBE2R) protocol. CBE2R controls the node mobility and prolongs the battery power of nodes by dividing the water depth into seven numbers of layers from top to seabed. CBE2R prolongs the battery power through powerful static courier nodes which are deployed from sea surface to seabed on different layers. Clustered-based routing mechanism with highest weighted value for data forwarding is based on seabed to bottom layer courier nodes through ordinary nodes. Bottom layer courier nodes collects the information from ordinary nodes and forwards to surface sink nodes by maximum power levels (p1, p2, …., pn-1) through courier nodes which are deployed in different layers. For performance analysis the NS2.30 with AquaSim is used. The simulation results of CBE2R are compared with energy efficient REEP, EMGGR, and DRP. From simulation results it is observed that the performance CBE2R is higher than REEP, EMGGR and DRP.

Data Delivery in Wireless Sensor Networks with Uncontrollable Mobile Nodes

Wireless sensor networks (WSNs) consist of low-powered devices that have computation, wireless communication and environment-sensing capabilities. These low-cost sensors are usually deployed in a dense and stationary manner for the periodic sensing of environmental phenomena. WSNs open the door for many monitoring applications in the military, in healthcare, and in environmental and urban studies. Mobile wireless sensor networks (MWSNs) are a subclass of WSNs in which some or all the sensors are mobile. Many environmental applications are designed and deployed on top of MWSNs in which the sensors' hosts are uncontrolled by end users (e.g., the OpenSense project for air pollution monitoring in the city of Zurich). MWSNs poses many challenges for newly designed applications. In this paper, we evaluate MWSNs with a location-based application. We test various data delivery schemes used by sensors in MWSNs, including GPRS, Wi-Fi, and Hybrid (both GPRS and Wi-Fi). We perform extensive simulation-based experiments using the ns2 simulator.

Static Node Center Opportunistic Coverage and Hexagonal Deployment in Hybrid Crowd Sensing

Mobile Crowd Sensing (MCS) is widely used in large-scale complex social sensing tasks even though it cannot offer reliable sensing quality yet due to the mobility restrictions. In order to solve the inadequate sensing opportunities provided by an MCS system, we focus on building a Hybrid Crowd Sensing (HCS) network by organizing both static and uncontrolled mobile nodes. We use the static node central opportunistic coverage to measure the sensing quality of HCS by analyzing the different features of coverage in the three regions and forming definitions. Our proposed approach can enable the static nodes to be deployed in the traditional hexagonal lattice, and mobile nodes to be located by smaller hexagonal lattices. Moreover, the analysis results demonstrate that the hexagonal lattice is more economical in both the number of mobile nodes needed by the seamless coverage SSA and network connectivity with the square grid. Finally, we make further analysis of the stream successful transmission probability, and find out that there are many complex influence factors of the static node central opportunistic coverage, such as the size of the time window T, the relative position of the start location and the end location, the number of mobile nodes participates stream transmission, mobile strategy of mobile nodes, opportunistic delegation mechanism, opportunistic routing mechanism, and so on. We modelize the lower limitation of it by a discrete Markov chain, and the simulation results show both the feasibility and rationality of using the static node central opportunistic coverage as the sensing quality metric.

Synchronization of Coupled Reaction-Diffusion Neural Networks with Time-Varying Delays via Pinning-Impulsive Controller

In this paper, global exponential synchronization stability in an array of linearly diffusively coupled reaction-diffusion neural networks with time-varying delays is investigated by adding impulsive controller to a small fraction of nodes (pinning-impulsive controller). In order to overcome the difficulty resulting from the fact that the impulsive controller affects only the dynamical behaviors of the controlled nodes, a new analysis method is developed. By using the developed method, two known lemmas on stability of delayed functional differential equation with and without impulses, and Lyapunov stability theory, several novel and easily verified synchronization criteria guaranteeing the whole network will be pinned to a homogenous solution are derived. Moreover, the effects of the pinning-impulsive controller and the dynamics of the uncontrolled nodes and the diffusive couplings on the synchronization process are explicitly expressed in the obtained criteria. Our results also show that we can always de...

Local convergence of general Steffensen type methods

We study the local convergence of a generalized Steffensen method. We show that this method substantially improves the convergence order of the classical Steffensen method. The convergence order of our method is greater or equal to the number of the controlled nodes used in the Lagrange-type inverse interpolation, which, in its turn, is substantially higher than the convergence orders of the Lagrange type inverse interpolation with uncontrolled nodes (since their convergence order is at most \(2\)).