Hierarchical Network Topology Research Articles

Exponential consensus for hierarchical multi‐agent systems with switching topology and inter‐layer communication delay

This study studies the exponential state consensus problem for hierarchical multi-agent dynamical systems with switching topology and inter-layer communication delay. A Lyapunov function is introduced to quantify the total disagreement among the nodes of a hierarchical multi-agent system. By using the stability theory of switched system and graph theory of hierarchical network topology, delay dependent sufficient conditions are proposed to achieve the exponential hierarchical average consensus with the average dwell time of the switching law larger than a minimum bound. Illustrative examples are provided to verify the effectiveness of the proposed approach.

Vertical Transmission of Social Roles Drives Resilience to Poaching in Elephant Networks

Network resilience to perturbation is fundamental tofunctionality in systems ranging from synthetic communication networks to evolved social organization [1]. While theoretical work offers insight into causes of network robustness, examination of natural networks can identify evolved mechanisms of resilience and how they are related to the selective pressures driving structure. Female African elephants (Loxodonta africana) exhibit complex social networks with node heterogeneity in which older individuals serve as connectivity hubs [2, 3]. Recent ivory poaching targeting older elephants in a well-studied population has mirrored the targeted removal of highly connected nodes in the theoretical literature that leads to structural collapse [4, 5]. Here we tested the response of this natural network to selective knockouts. We find that the hierarchical network topology characteristic of elephant societies was highly conserved across the 16-year study despite ∼70% turnover in individual composition ofthe population. At a population level, the oldest available individuals persisted to fill socially central positions in the network. For analyses using known mother-daughter pairs, social positions of daughters during the disrupted period were predicted by those of their mothers in years prior, were unrelated to individual histories of family mortality, and were actively built. As such, daughters replicated the social network roles of their mothers, driving the observed network resilience. Our study provides a rare bridge between network theory and an evolved system, demonstrating social redundancy to be the mechanism by which resilience to perturbation occurred in this socially advanced species.

Spatial patterns of cultural tourism in Portugal

This paper analyzes recurrent spatial patterns that characterize package holidays for mainland Portugal by applying a cluster analysis to cultural attractions and the number of overnight stays assigned to each municipality. The empirical results show that organized tourist programs based on cultural heritage break reduce to some extent the asymmetry of the spatiality of the Portuguese tourism model that historically was concentrated around the Algarve. This research shows that the articulation of nodes and their Euclidean distance in the analyzed programming models does not have a deterministic relationship with geographical and physical proximity. Rather the analysis unravels cumulative attraction patterns based on a hierarchical network topology that drains tourism from strategic gateways (Lisbon and Oporto) to peripheral municipalities.

HERO: Hierarchical Energy Optimization for Data Center Networks

The rapid escalating power consumption has become critically important to modern data centers. Existing works on reducing the power consumption of network elements formulate the power optimization problem for a general network topology and require a centralized controller. As the scale of data centers increases, the complexity of solving this optimization problem increases rapidly. Inspired from the hierarchical data center network (DCN) topologies and data center traffic patterns, we design a two-level, pod-level, and core-level power optimization model, namely, Hierarchical EneRgy Optimization (HERO), to reduce the power consumption of network elements by switching off network switches and links while still guaranteeing full connectivity and maximizing link utilization. Given a physical DCN topology and a traffic matrix, we illustrate that two-level power optimizations in HERO fall in the class of capacitated multicommodity minimum cost flow (CMCF) problem, which is NP-hard. Therefore, we design several heuristic algorithms based on different switch elimination criteria to solve the proposed HERO optimization problem. The power-saving performance of the proposed HERO model is evaluated by several experiments with different traffic patterns. Our simulations demonstrate that HERO can reduce power consumptions of network elements effectively with reduced complexity.

Spherical Target Recognition using Time-Domain Multiscale Approximation of Scattered Signals

Classification of similar shaped objects from scattered electromagnetic waves is a difficult problem to solve. as it heavily depends on the aspect angle. Eliminating the effects of the aspect angle is possible by extracting distinguishable features from the scattered signals. These features should be robust to noise effects especially at SNR levels. where noise effects become dominant on the scattered signal. In this paper. we propose a target classification method. which uses a structural feature set extracted from scattered signal. Prior to feature extraction. a multi-scale approximation is performed using hierarchical radial basis function network topology to suppress the effects of noise on scattered signal. After principle component analysis. k-fold cross validation based experiments is performed. Results show that spherical targets are recognized successfully up to -10dB SNR.

Analysis of Monitoring System Reliability for Wind Turbine Based on Wireless Sensor Network

In this paper, based on wireless sensor network technology, we propose the monitoring system for wind tur- bine. In order to ensure that the monitoring system can completely and accurately obtain the condition monitoring infor- mation, using exponential distribution function, we establish the reliability model. Because the topology control tech- niques can improve the monitoring system reliability, we present the hierarchical network topology for monitoring sys- tem. Then, combined with the presented hierarchical network topology, we study the reliability model. Finally, simulation shows that the network parameters affect the reliability and the working time of monitoring system.

Cloud Computing in Three Phase Scheduling Algorithm Based on Service Quality

Assurance issues for cloud computing’s service quality; propose a hierarchical network topology on the basis of the three-stage scheduling algorithm. The algorithm ensures that each work to be performed can be assigned to the appropriate resources, and can effectively improve the load of each node and reduce the waste of resources. FCFS, SJF, OLB and Min-Min (MM) scheduling algorithm’s simulation results show that the algorithm can not only make the work get the minimum completion time, but also the service node operation achieve the load balancing.

Quantitative Analysis of Network Configuration in Randomized Distribution Wireless Sensor Networks

Utilizing the clustering algorithm to form hierarchical network topology is the common method of implementing network management and data aggregation in wireless sensor networks. Many of the clustering algorithms heuristically determine the node energy, optimal node communication radius, and clustering radius, even though these parameters affect energy consumption of the entire network. In order to minimize energy consumption of the entire network, we present the optimal configuration by quantitative analysis when the nodes follow the random distribution. With the conclusion of quantitative analysis in single cluster expanded to the general case, the minimum of the network energy and optimal clustering radius are figured out. Simulated tests indicate that the optimal configuration can contribute to building more balanceable clustering structure and enhancing the network life cycle obviously.

A complete hierarchical key management scheme for heterogeneous wireless sensor networks.

Heterogeneous cluster-based wireless sensor networks (WSN) attracted increasing attention recently. Obviously, the clustering makes the entire networks hierarchical; thus, several kinds of keys are required for hierarchical network topology. However, most existing key management schemes for it place more emphasis on pairwise key management schemes or key predistribution schemes and neglect the property of hierarchy. In this paper, we propose a complete hierarchical key management scheme which only utilizes symmetric cryptographic algorithms and low cost operations for heterogeneous cluster-based WSN. Our scheme considers four kinds of keys, which are an individual key, a cluster key, a master key, and pairwise keys, for each sensor node. Finally, the analysis and experiments demonstrate that the proposed scheme is secure and efficient; thus, it is suitable for heterogeneous cluster-based WSN.

The Hierarchical Network Topology Management System based on Managed Object and View Mechanism

Now how to improve the developing efficiency and enhance the scalability of network management system has become a hot issue in the current research. In this paper, according to the actual demands, understanding the functional requirements and analyzing the process of network topology management, we propose the hierarchical network topology management system based on managed object and view mechanism. Using an object-based management method, it achieves the expansion of the three-layer model of network topology management; using the view mechanism, it reduces the dependence on the specific needs for the system and achieves a hierarchical network topology management system.

Hierarchical excitatory synaptic connectivity in mouse olfactory cortex

Topological motifs in synaptic connectivity-such as the cortical column-are fundamental to processing of information in cortical structures. However, the mesoscale topology of cortical networks beyond columns remains largely unknown. In the olfactory cortex, which lacks an obvious columnar structure, sensory-evoked patterns of activity have failed to reveal organizational principles of the network and its structure has been considered to be random. We probed the excitatory network in the mouse olfactory cortex using variance analysis of paired whole-cell recording in olfactory cortex slices. On a given trial, triggered network-wide bursts in disinhibited slices had remarkably similar time courses in widely separated and randomly selected cell pairs of pyramidal neurons despite significant trial-to-trial variability within each neuron. Simulated excitatory network models with random topologies only partially reproduced the experimental burst-variance patterns. Network models with local (columnar) or distributed subnetworks, which have been predicted as the basis of encoding odor objects, were also inconsistent with the experimental data, showing greater variability between cells than across trials. Rather, network models with power-law and especially hierarchical connectivity showed the best fit. Our results suggest that distributed subnetworks are weak or absent in the olfactory cortex, whereas a hierarchical excitatory topology may predominate. A hierarchical excitatory network organization likely underlies burst generation in this epileptogenic region, and may also shape processing of sensory information in the olfactory cortex.

Topology Construction Mechanism of Behavior-Controllable Hierarchical Military Peer to Peer Network

In order to meet the special needs of military applications, network users were classified according to characteristics of users and a hierarchical behavior-controllable P2P network topology construction was designed. In the new construction, different information has different circulation range and the survivability and expansion characteristics of the P2P network were made full use.

Tunnel-Free Scheme Using a Routing Table in a PMIPv6-Based Nested NEMO Environment

In this paper, we propose a novel tunnel-free scheme in a proxy mobile IPv6 (PMIPv6)-based nested network mobility environment; several mobile nodes (MNs) and mobile routers (MRs) compose a hierarchical wireless network topology. Because tunnels created by several MRs overlap and data packets travel along several local mobility anchors (LMAs), the utilization of the wireless section is reduced and the packet forwarding path of the wire-line section is not optimal. In our tunnel-free scheme, the mobile access gateway (MAG) plays an important role in both the wireless and wire-line sections. Using a local binding update, this tunnel-free scheme forwards data packets with a host-based routing table without any tunnel. Establishing a direct tunnel between the MAG and the last LMA, this scheme removes nested tunnels between intermediate LMAs and MRs, and optimizes the forwarding path to the MN in the wire-line section.

Load-Balanced Clustering Algorithm With Distributed Self-Organization for Wireless Sensor Networks

Wireless sensor networks (WSNs) are composed of a large number of inexpensive power-constrained wireless sensor nodes, which detect and monitor physical parameters around them through self-organization. Utilizing clustering algorithms to form a hierarchical network topology is a common method of implementing network management and data aggregation in WSNs. Assuming that the residual energy of nodes follows the random distribution, we propose a load-balanced clustering algorithm for WSNs on the basis of their distance and density distribution, making it essentially different from the previous clustering algorithms. Simulated tests indicate that the new algorithm can build more balanceable clustering structure and enhance the network life cycle.

Distributed Processing of Probabilistic Top-k Queries in Wireless Sensor Networks

In this paper, we introduce the notion of sufficient set and necessary set for distributed processing of probabilistic top-k queries in cluster-based wireless sensor networks. These two concepts have very nice properties that can facilitate localized data pruning in clusters. Accordingly, we develop a suite of algorithms, namely, sufficient set-based (SSB), necessary set-based (NSB), and boundary-based (BB), for intercluster query processing with bounded rounds of communications. Moreover, in responding to dynamic changes of data distribution in the network, we develop an adaptive algorithm that dynamically switches among the three proposed algorithms to minimize the transmission cost. We show the applicability of sufficient set and necessary set to wireless sensor networks with both two-tier hierarchical and tree-structured network topologies. Experimental results show that the proposed algorithms reduce data transmissions significantly and incur only small constant rounds of data communications. The experimental results also demonstrate the superiority of the adaptive algorithm, which achieves a near-optimal performance under various conditions.

Preventing Direct Communication between a Sensor and Sink Node with the Help of Hybrid Network Topology for Energy Conservation in Wireless Sensor Network

Wireless Sensor Networks (WSNs) are paving a way of miniaturization of sensors and actuators by proving a way of boost in the wireless communications by constructing small sized, low power and inexpensive sensor devices that posses high-speed sensing, computational, and communication capabilities. This paper presents the combination of Hybrid Hierarchical Network Topology and Use of different Communication Techniques like Sleep & Wait: Transmission of Data and Low Power Listening: Reception/Listening. This paper proposes a system in which the setup of intermediate nodes (Parent nodes) is done to prevent direct communication between a Sensor and Sink node, which in a nutshell prevents large wait times for transmission.

A Secure Mutual Authentication Protocol for Roaming in Wireless Mesh Networks

Roaming in wireless mesh networks (WMNs) requires that mobile nodes complete access authentication fast while protecti ng the identities of mobile nodes. In this paper, after analyzing some current authentication protocols for roaming in wireless mesh networks, we propose a new protocol based on multi-signature and three-party key agreement with a zone-based hierarchical network topology and prove the security properties of the protocol through formal analysis that is based on the strand space model. We also demonstrate the reliability and performance of the proposed protocol through network simulation s .

An Efficient Cluster Head Selection Algorithm for Wireless Sensor Networks –Edrleach

The Cluster-head Gateway Switch Routing protocol (CGSR) uses a hierarchical network topology. CGSR organizes nodes into clusters, with coordination among the members of each cluster entrusted to a special node named cluster-head. The cluster head selection is done with the help of any of the algorithm for cluster head selection. Energy is the primary constraint on designing any Wireless Networks practically. This leads to limited network lifetime of network. Low-Energy Adaptive Clustering Hierarchy (LEACH) and LEACH with deterministic cluster head selection are some of the cluster head algorithms that enable to optimize power consumption of WSN. There are various factors like density & distance, threshold based, power efficient. Load balancing and scalability are the other factors which plays important role in the selection of Cluster head. Algorithms based on load balancing reduce communication cost to a great extent. The algorithms that this study is focused are A Density and Distance based Cluster Head, An Energy Efficient Algorithm for Cluster-Head Selection in WSNs, Consumed Energy as a Factor for Cluster Head. These three algorithms are analyzed and studied in this paper. The analysis of these algorithms gave birth to a new algorithm called EDRLEACH, which is proposed through this paper. Keywords-Cluster head,energy efficient algorithms,selection head algorithms, wireless sensor,networks.

Leveraging Pause Time Distributions for StableCluster-based Data Gathering in MultihopCell Phone-based Sensor Network

The application of Multihop Cell phone-based Sensor Network (MCSN) technologies for the Data gathering service has brought new challenges in maintaining communication clusters of Cluster heads for long time durations. Stable clustering methods reduce the reclustering frequency in MCSN and provide for a more energy-efficient hierarchical network topology. The stability is defined in terms of Dominating set updates or reclustering frequency as average number of cluster formation per unit time. During creation of MCSN clusters, each Cell phone chooses a head cell phone to send the sensed data. In this paper, we improve cluster stability by the addition of one pause time-based weighting parameter to a well-known weighted clustering algorithm (WCA). The WCA uses current mobility index of mobile nodes to predict the stability of the network. Newly introduced parameter is related with cell phone user’s mobility-specific pause time distribution.

A Clustering Algorithm for Wireless Sensor Networks Basing on Distance and Distribution

Wireless sensor networks (WSNs) detect and monitor the outside physical state by the sensor nodes organizing automatically. Utilizing clustering algorithm to form hierarchical network topology is the common method which implements managing network and aggregating data in WSNs. Different from the previous clustering algorithms, this article proposes a clustering algorithm for WSNs based on distance and distribution to generate clusters considering residual energy of nods in WSNs with inhomogeneous distribution. The simulation result indicates that the algorithm can establish more balanceable clustering structure effectively and enhance the network life cycle obviously.<b></b>