Special Kind Of Network Research Articles

A fractal power-law approach for investigating the interactions between reservoir microstructure and gas migration

As one of the most significant clean energy sources, the migration characteristics and extraction processes of coalbed methane (CBM) have been extensively studied. The structural distribution and evolutionary characteristics of reservoir fractures, as the main conduit for gas migration, significantly affect the permeability and gas production. However, few models have been able to quantitatively and accurately explore reservoir micro–macro interactions under coupled thermal-fluid–solid effects. This work develops a new highly coupled model based on the widely adopted power-law function to quantify reservoir thermal conduction effect, gas pressure evolution, reservoir deformation, in situ stress, the adsorption–desorption effect, and reservoir microstructure evolution. Three parameters are adopted to quantitatively characterize the reservoir structure: (1) fracture power index αf (to characterize the fracture density), (2) fracture length ratio rf (to characterize the fracture size), and (3) the maximum fracture length l. The results demonstrate that the fractal network is a special kind of network in the power-law length distribution. The proposed power-law seepage model is able to accurately characterize the evolution of reservoir microstructure and the impact of microevolution on extraction under multi-field coupling effects, compared to the traditional power-law model. The proposed model can provide a good theoretical and practical support for the study of CBM migration and extraction.

A Multi-seed Nodes Selection Strategy for Influence Maximization Based on Reinforcement Learning Algorithms

Identifying influential individuals in the dissemination of information is an important topic in the study of social networks. Up to now, most of the previous works of Influence Maximization on social networks has been limited to selecting seeds based on a certain structural feature of the networks. These algorithms only consider a certain structural feature and cannot effectively select suitable seeds on social networks when the network has complex and changeable structures. Most of them only get good results on a special kind of networks. In order to find the most suitable nodes as the initial seed nodes in various social networks, we designed a new seeds selection algorithm which is based on reinforcement learning (IMQ). Our approach takes advantage of the characteristics of reinforcement learning’s agent that can continuously interact with the environment, this algorithm can be adapted to select the most suitable nodes as seed nodes on various social networks. It fully considers the influence of the network structure characteristics on the influence propagation process, so that this method can select the best nodes as seeds on social networks with different topologies. In order to demonstrate the superiority of the approach, we conducted comparative experiments on six real social networks. Experimental results show that IMQ can be applied to various structural social network, and has stronger universality than traditional methods.

Minimum Flows in Parametric Dynamic Networks. The Static Approach

The problems of flows in parametric networks extend the classical problems of optimal flow to some special kind of networks where capacities of certain arcs are not constants but depending on several parameters. Consequently, these problems consist of solving a range of ordinary (nonparametric) optimal flow problems for all the parameter values within certain sub-intervals of the parameter values. Although classical network flow models have been widely used as valuable tools for many applications [1], they fail to capture the essential property of the dynamic aspect of many real-life problems, such as traffic planning, production and distribution systems, communication systems, evacuation planning, etc. In all these cases, time is an essential component, either because the flows take time to pass from one location to another, or because the structure of the network changes over time. Accordingly, the dynamic flow models seem suited to catch and describe different real-life dynamic problems such as network-structure changing over time or timely decision-making, but, because of their complexity, these models have not been as thoroughly investigated as those of classical flows. This article presents and solves the problem of the minimum flows in a parametric dynamic network. The proposed approach consists in applying a parametric flow algorithm in the reduced expended network which is obtained by expanding the original dynamic network. A numerical example is also presented for a better understanding of the used approach.

Random walks on a tree with applications

The various dynamics of many complex systems, both natural and artificial, can be well described as random walks on a newly proposed yet powerful object known as a complex network. Here we consider random walks on a special kind of network, a tree. Using the methods of probability-generating functions, we derive a close connection between the widely studied parameters mean first-passage time M and mean shortest path length A on trees. This suggests that for a given tree, the analytic value for M can be easily obtained by calculating the value A when determining the latter is more convenient and vice versa. As a result, the well-known T graph is selected as one of various applications of our methods, and we then obtain an exact solution to its quantity M. On the one hand, the result addressed here is in perfect agreement with previous ones. On the other hand, our method is easier to manipulate than most preexisting ones, for instance, methods from spectral graph theory, since no complicated techniques are involved.

Review and Comparison of Emerging Routing Protocols in Flying Ad Hoc Networks

With the development of Unmanned Air Vehicle (UAV) communication, Flying Ad Hoc Network (FANET) has become a hot research area in recent years, which is widely used in civil and military fields due to its unique advantages. FANET is a special kind of networks which are composed of UAV nodes, and can be used to implement data transfer in certain unique scenarios. To achieve reliable and robust communication among UAVs, a routing algorithm is the key factor and should be designed elaborately. Because of its importance and usefulness, this topic has attracted many researchers, and various routing protocols have also been put forward to improve the quality of data transmission in FANETs. Thus, in this paper, we give a survey on the state-of-the-art of routing protocols proposed in recent years. First, an in-depth research of the routing in FANETs recently has been brought out by absolutely differentiating them based on their routing mechanism. Then, we give a comparative analysis of each protocol based on their characteristics and service quality indicators. Finally, we propose some unsolved problems and future research directions for FANET routing.

Approach of Improved Topology Development Protocol In Ad Hoc Network Minimizing The Number of Hops And Maintaining Connectivity of Mobile Terminals Which Move From One To The Others

Wireless ad-hoc mesh network is a special kind of network, where all of the nodes move in time. Node is intended to help relaying packets of neighboring nodes using multi-hop routing mechanism in order to solve problem of dead communication. Wireless mesh network which engages broadcasting and contains multiple hops become increasingly vulnerable to problems such as routing problem and rapid increasing of overhead packets. During this progress, the delay on account of multi hop characteristics and redundant packets caused by communication nature potentially existed during communication. Typically, delay will increase in linearity with number of hops. There is a certain minimum level of delay that will be experienced due to the time it takes to transmit a packet through a link. Topology development holds a significant point prior to the data transmission. Without improved topology development protocol, this problem can decrease network’s performance in overall data transmission. We analyze the delay performance of a multi-hop wireless network with a dynamic route between each source and final destination pair. There are fluctuate interference constraints on the set of links that impose a fundamental delay performance of any instant network topology. At first, we present a similar Link State Routing network simulation to derive such referential lower bounds. We conduct extensive simulation studies to suggest that the average delay of multi-hop transmission policy can be made lower compared to the referential bound by using appropriate functions of network metrics. This paper provides a broadcast framework that engages various network metrics and at the same time maintaining connectivity of nodes (mobile terminals). The framework captures the essential features of the wireless network metrics, i.e. bandwidth, throughput, network buffer, direction, and round trip time. This research is useful since, in many cases, it find that the throughput is the most important parameter in reduction of delay transmission. This result is confirmed with another composite simulation result. Most of network hop delay is impacted with this composite metric, particularly in delay minimization on the longer hops. The reduction achievement on average delay by this algorithm is 0.577% and the total average delay reduction for this simulated network is 0.683%. This research will be further designed primarily for achieving maximum throughput in the multiple wireless network area.

Load Path Network Method: An Equilibrium-Based Approach for the Design and Analysis of Structures

Load path network method is an equilibrium-based method for the design and analysis of three-dimensional structures based on the lower bound theorem of the theory of plasticity. The goal of this method is to stimulate the exploration of possible three-dimensional flows of internal forces in equilibrium in a structure in order to help the integration of structural concerns in the design process of a building project. For creating a three-dimensional load path, the method constructs a strut-and-tie model by means of a special kind of network which connects a given set of points in three-dimensional space. This network is statically determinate and non-kinematic. The construction process of such networks may be easily controlled in order to obtain suitable load paths. This paper presents the concept, the main steps of the method, intuitive strategies for controlling it in order to obtain suitable results and a discussion of its main applications.

Wireless Sensor Network: An Emerging Technology

Wireless sensor network is a special kind of network that differs from the conventional communication networks in terms of architecture and deployment. Dynamic in nature, the wireless sensor networks have added a new dimension not only to the further exploration in a hard-to-reach environment, but also to the complexity of network management. Wireless sensor networks are emerging very rapidly and have already demanded keen interests from researchers. As a relatively new concept in the world of communication, a number of aspects are being explored by the researchers including routing and security features of the wireless sensor networks. Like any wireless network, power consumption has always been a critical issue for wireless sensor networks. This is also due to the environmental constraint in which the wireless sensor networks are normally deployed. This paper provides an overview of this emerging technology by addressing its architecture, deployment and key issues e. g. energy-efficiency, routing, reliability and security

Successful Transmission Rate of Mobile Terminals with Agents in Segmented Ad Hoc Network

Mobile Wireless Ad-Hoc Network (MANET) is a special kind of network, where all of the nodes move in time. Random movement is the commonly used to model the mobility in this network. Beside as a host, each node is intended to help relaying packets of neighboring nodes using multi-hop routing mechanism in order to solve problem of dead communication. In recent years, a variety of routing protocols have been proposed specially to accommodate this environment followed with its performance evaluations, likes DSDV, DSR, AODV, and extension OSPF. Researches in this network are mostly simulation based. Research efforts haven't focused much in evaluating network performance when applied to variable number of nodes that involving agents and distributed over several network areas. The paper performed simulations using MANET simulator, which carried out based on the extension OSPF routing protocol. The modification of OSPF protocol had intended to suit the OSPF standard mechanisms for operating with high performance over wireless networks characterized by a broadcast-based transmission medium, in which the physical layer connectivity is not fully meshed. Extensive simulation scenarios have been conducted in the simulator with various numbers of nodes, random and uniform movement direction, and different agent’s quantity with different size of network areas. In the performance evaluation of successful transmission (data) packets, the OSPF protocol with throughput weighted metric will be tested under different combination conditions of scenarios.

Stability Analysis and Hadamard Synergic Control for a Class of Dynamical Networks

Hadamard synergic control is a new kind of control problem which is achieved via a composite strategy of the state feedback control and the direct regulation of the part of connection coefficients of system state variables. Such a control is actually used very often in the practical areas. In this paper, we discuss Hadamard synergic stabilization problem for a class of dynamical networks. We analyze three cases: 1) Synergic stabilization problem for the general twonodenetwork. 2) Synergic stabilization problem for a special kind of networks. 3) Synergic stabilization problem for special kind of networks with communication timedelays. The mechanism of the synergic action between two control strategies: feedback control and the connection coefficients regulations are presented.

Systemic evaluation of cross‐border networks of actors: Experience with a German‐Polish‐Czech cooperation project

Cross‐border networks of actors constitute a special type of cross‐border cooperation as well as a special kind of network. This form of cooperation is characterized by a high degree of uncertainty, particularly in the case of the Polish‐German and the Czech‐German borders with their problematic history and rather weak traditions of cooperation. Evaluations can help to raise the effectiveness of cross‐border networks. This article refers to the concept of systemic evaluation. Such an evaluation is a collective process of learning and deliberation which is intended to increase the problem‐solving capacity of the system and to involve the participants and users from the beginning of the process. The main question dealt with in this article is how systemic evaluations of cross‐border networks of actors have to be designed and implemented. In the article, a brief survey on the state of art of systemic, participatory cross‐border evaluation is supplemented by a case study of the evaluation of the project Enlarge‐Net. The conclusions include the findings that systemic evaluations cannot be regarded separately from the intervention logic and that evaluators who are dealing with systemic evaluations of cross‐border networks of actors need a diverse tool box and have to adapt their methods to the actual phase of the cooperation.