Reliability Evaluation Of Networks Research Articles

The extra connectivity and extra diagnosability of regular interconnection networks

Reliability assessment of interconnection networks is critical to the design of multiprocessor systems. Extra connectivity and extra diagnosability are two important metric parameters for the reliability evaluation of interconnection networks. In this paper, we first establish that the i-extra connectivities of regular networks with some conditions Gn are (i+1)n−2i for i=1,2, where n ≥4, and then determine that the i-extra diagnosabilities of the networks under the PMC model and the MM* model are (i+1)n−i for i=1,2, where n ≥4. Furthermore, two polynomial time diagnostic algorithms of regular interconnection networks under the PMC and MM* model are described. Finally, the corresponding extra connectivities and extra diagnosabilities of some networks, including the star networks, the pancake networks and the burnt pancake networks, can be derived by our results.

Exact reliability evaluation of infrastructure networks using graph theory

AbstractReliability analysis of Infrastructure Networks (INs) is gaining recognition in the research literature. However, most of the work on reliability evaluation of INs have focused on simulation analysis and, therefore, unable to calculate the exact reliability. Additionally, these methods lack the capability of achieving a closer adherence to INs. The presented paper aims at filling these gaps by simplifying the process of computing the exact reliability of an IN through the decomposition of the network into a set of series and parallel configuration of its elements. In exemplifying the method, an illustrative example is presented and a brief discussion on the usefulness and limitation of the method is described.

Application of cut set method to reliability evaluation of mine ventilation networks

Providing a fresh and cool airflow in underground mines is one of the main concerns during mining. Destruction of support systems, the presence of undesirable objects in the airway and distortion of airflow are the parameters involved that would result in pressure loss, which would affect the ventilation network. There are a lot of research works about the ventilation network planning that consider the confidence in the planning but how reliable are these designs? These questions can be answered using the quantitative reliability evaluation. For the reliability evaluation of mine ventilation network, tunnel resistance and flow rate changes for all branches are considered as the reliability indices and criteria. This paper describes a stepwise method for evaluation of the underground coal mine network reliability associated with major losses using the cut set method. The reliability of the entire network is achieved by the reliability of every single component. The proposed model is implemented by the Takht coal mine. The Takht mine ventilation network probability of failure is in the range of 19-100% so reliability is in the range of 0-81% for the entire ventilation network.

Evaluation of stochastic flow networks susceptible to demand requirements between multiple sources and multiple destinations

Computer and communication applications such as big data analytics services, social networks, enterprise business and mobile applications often require to simultaneously pass data of different sizes between multiple source and multiple destinations in the network. In practice, the nodes in the communication networks are often connected through multiple intermediate links of different types with varying failure probabilities. Failure of intermediate links can adversely affect data transmission between source and destination nodes; thus, they can impact the quality of service. Therefore, reliability evaluation of such networks is of subtle importance in today’s service dependent world. This article presents an efficient method for reliability evaluation of stochastic flow networks that can pass various demands simultaneously from multiple source nodes to multiple destination nodes. The proposed method has three steps: First step obtains the combined minimal cut sets between the given set of source and destination nodes. Second step generates the set of simultaneous upper boundary flows for the varying demands using the combined minimal cut sets. Third step calculates the network unreliability by applying the Sum of Disjoint Product method on the upper boundary flows. The reliability of the network, i.e., the probability that the network can simultaneously pass the set of demands, is calculated as 1-Unreliability. The MATLAB simulation of the proposed method on bench mark networks show that the proposed approach takes less computational time than the existing method.

A New Solution Algorithm for the Multistate Minimal Cut Problem

Reliability evaluation is a useful tool for network performance demonstration, and therefore has become an increasingly relevant task in network design and operation. The multistate minimal cut (called d -MC for short) method is a popular algorithm for reliability evaluation of multistate flow networks. This article focuses on d -MC problem, and presents some new results to improve its solution. Grounded on the newly obtained results, an algorithm is proposed to find d -MCs, together with discussions on its time complexity that compares favorably with the existing methods. An illustration of the presented algorithm is provided by solving a simple example. Furthermore, numerical experiments and a case study are conducted to demonstrate the advantage and the utility of the proposed algorithm, respectively.

Reliability evaluation of complete cubic networks

Fault diagnostic analysis is extremely important for interconnection networks. Given a graph G and a positive integer g, the g-extra connectivity of G (denoted by ) is the minimum cardinality of a subset S of such that G−S is disconnected and every remaining component has at least g + 1 vertices. The g-extra diagnosability of G (denoted by ), is the maximum number of faulty vertices that the system can guarantee to identify under the condition that every fault-free component contains at least g + 1 vertices. The t/k-diagnosis strategy can detect up to t faulty vertices which might include at most k misdiagnosed vertices. In this paper, we first determine for , , where is an n-dimensional complete cubic network, which generalises the hierarchical cubic network. Moreover, we establish under the PMC model (, ) and under the MM* model (, ), respectively. Furthermore, we show that is -diagnosable under the PMC model. As a consequence, we also derive the related results of the n-dimensional hierarchical cubic network .

Reliability Evaluation and Reliability-Based Optimal Design for Wireless Sensor Networks

Wireless sensor networks (WSNs) are widely applied in many fields. It is of concern to evaluate and improve the reliability of a WSN to ensure a highly reliable operation in practice. In this paper, the reliability of WSNs is analyzed by considering random failures, energy consumption, environmental randomness, and interference, due to their nonnegligible effects. For a typical WSN consisting of multiple sensor nodes and a sink node, we suppose that the WSN is functional if the number of the sensor nodes that are interconnected and connected to the sink node is no less than a minimum required number. Two novel reliability indices, the generalized terminal reliability, and the average generalized terminal reliability, are proposed to assess the reliability of WSNs, and their calculation methods are provided based on the algebraic graph theory and Monte Carlo simulations. Moreover, an optimization method with three stages is presented to comprehensively optimize the design of a WSN from the view point of reliability. Finally, a numerical example is given to illustrate the effectiveness of the proposed methods.

A Binding Algorithm of Lower Boundary Points Generation for Network Reliability Evaluation

Network reliability evaluation for a stochastic flow network (SFN) can be computed in terms of all lower boundary points (LBPs). Although several algorithms have been presented in the literature as solutions for the LBP problem, the efficiency is always occurring at the present for the large SFN. In this paper, a binding technique generating binding-flow vectors is therefore developed to narrow down the searching range of flows for demand. This technique is able to reduce the loading of the candidate comparison procedure greatly. An algorithm based on this binding technique is proposed to solve the LBP problem. We compare the performance of the proposed algorithm to well-known algorithms in terms of CPU time, through three benchmark networks and a practical case. The experimental results show the functional efficiency of our proposed binding LBP algorithm.

An MP-based approximation algorithm on reliability evaluation of multistate flow networks

In recent decades, multistate two-terminal reliability problem has attracted several researchers, and accordingly many exact and approximation approaches have been proposed in the literature in terms of minimal cuts (MCs) or minimal paths (MPs) to address this problem. Here, an MP-based approximation approach is developed based on exact algorithms. With all the MPs at hand, the approach rearranges the MPs ascendingly with respect to their lengths and then sets the flow on some MPs to be zero which turns to reduce the computing cost in solving the problem. We provide the complexity results, and by employing some benchmarks and one thousand randomly generated networks illustrate that not only in many cases the proposed approach determines very good approximate solutions much faster than the exact algorithms, but also in many other cases it even determines exact solutions significantly faster than the available exact algorithms in the literature. Moreover, the Dolan-Moré performance profile affirms the efficiency of our proposed algorithm. Finally, we state how to compute the system reliability by using the d-MPs, and show that from a very good approximation set of d-MPs, the system reliability is approximated with a very good accuracy.

Distribution Network Reliability Evaluation with Load Importance Degree and Isolated Island Operation

Supply power for important load in priority is the fundamental principle during power shortage. For the reason that the existing power load classification principle is too simple to compare the importance degree of loads at the same level, this paper proposed a comprehensive evaluation method of load importance degree. First, an indicator system is established to measure load importance. Then a comprehensive evaluation model is designed basing on improved rank correlation analysis method, which sets weights based on subject and object analysis and calculates the importance degree value according 4 indicators, including outage cost. Finally, evaluating the distribution network reliability with load importance degree. Simulation results on IEEE-RBTS BUS6 system shows the validity and practicality.

Bi-objective optimization for a multistate job-shop production network using NSGA-II and TOPSIS

A job-shop production system (JPS) is a manufacturing system wherein each workstation configures multiple types of machines to produce small batches of a variety of products. In each workstation of a JPS, the number of machines that operate normally exhibits multiple levels of capacity owing to failures, partial failures, and maintenance. That is, the number of normal machines in each workstation is stochastic (i.e., multistate). To analyze such a JPS, the JPS is transformed into a multistate job-shop production network (MJPN) using a network topology. For the MJPN, a critical issue is to maximize the network reliability and to minimize the purchase cost when setting up the JPS. To achieve such bi-objective optimization, a machine vector (MV) representing the current number of normal machines in each workstation is introduced to evaluate network reliability. An algorithm based on a depth-first search (DFS) with an expanding technique is proposed to search all MVs for satisfying demand. Subsequently, to obtain a machine configuration (MF) simultaneously having the maximal network reliability and the minimal purchase cost, a two-stage approach is developed based on the non-dominated sorting genetic algorithm II (NSGA-II) and the technique for order of preference by similarity to ideal solution (TOPSIS). A real case of t-shirt production is utilized to illustrate the proposed method.

Expanding a complex networked system for enhancing its reliability evaluated by a new efficient approach

The economic development and social well-being of a society are highly dependent on many complex networked systems, such as power transmission and distribution, telecommunications, transportation and so forth, which calls for the enhancement of their reliable functioning. To fulfil this purpose, the first essential step is to effectively evaluate their reliability, which is intractable since they usually contain a large amount of components organized via complex structures. To deal with this computational complexity, this research proposes a new network reliability evaluation approach by identifying minimal path sets that may have edges in common, but consist of only parallel and series structures when considered together. Our proposed approach can efficiently approximate network reliability more precisely than the existing edge-packing methods. We then propose a multi-objective optimization approach to solve the problem of expanding a complex networked system to enhance its reliability. The solutions obtained by our proposed approach can help in well understanding the trade-off between the reliability and cost of network expansion solutions. Finally, an application of the proposed method to the high-speed railway network of China is implemented.

Evaluation of Transportation Network Reliability under Emergency Based on Reserve Capacity

There are differences between the requirements for traffic network for traffic demand in daily and emergency situations. In order to evaluate how the network designed for daily needs can meet the surging demand for emergency evacuation, the concept of emergency reliability and corresponding evaluation method is proposed. This paper constructs a bilevel programming model to describe the proposed problem. The upper level problem takes the maximum reserve capacity multiplier as the optimization objective and considers the influence of reversible lane measures taken under emergency conditions. The lower level model adopts the combined traffic distribution/assignment model with capacity limits, to describe evacuees’ path and shelter choice behavior under emergency conditions and take into account the traits of crowded traffic. An iterative optimization method is proposed to solve the upper level model, and the lower level model is transformed into a UE assignment problem with capacity limits over a network of multiple origins and single destination, by adding a dummy node and several dummy links in the network. Then a dynamic penalty function algorithm is used to solve the problem. In the end, numerical studies and results are provided to demonstrate the rationality of the proposed model and feasibility of the proposed solution algorithms.

Determination of land side accessibility of Indian metro hub airports w.r.t. travel-time reliability

ABSTRACTAviation sector is one of the fastest growing industries in India where fast mobility and value of time become the key components. Therefore, reliability is the most important performance indicator of a time-dependent system. Reliability of a system has huge influence on its efficiency, capacity utilisation and economic benefits. The extent of connectivity of the network not only depends on inter-airport connections, but also the land accessibility to and from the airports. This study has been done extensively based on all the reliability parameters in accessing metro hub airports in India. In the current scenario, most of the Indian airports have unreliable access modes to airports, regardless of private and public transport options, latter being the worst due to heavily clogged highways and road system. This paper analyses the travel-time reliability of the airport link/s for six metro airports in India using different reliability indices. A critical evaluation of network reliability in six metro hub airports with respect to private mode (car) and available public transport (bus & metro/urban rail) is also carried out followed by their ranks. Reliability indices for bus and metro/urban rail are generated separately and a combined index is developed further.

An efficient searching method for minimal path vectors in multi-state networks

Searching for minimal path vectors (MPVs) is an important topic in solving network related problems, especially for the evaluation of network reliability. One of the popular approaches, namely the three-stage method (TSM), is influenced deeply on the efficiency of searching for minimal path vectors in multi-state networks (MSN). TSM consists of three stages, i.e., searching for all minimal path sets, searching for all MPVs, and calculating union probability on MPVs. After reviewing previous works in the literaure, this paper proposes a more efficient method based on cyclic check on the candidates of MPVs, which can do an efficient searching for MPVs in MSNs and even reduce the three-step approach to two-step approach. Benchmarking with the well-known algorithms are made in this paper, and more complicated networks are also examined for verification of the proposed method.

A New Node-Based Concept for Solving the Minimal Path Problem in General Networks

The validation and evaluation of network reliability are significant issues in the planning, design, and control of systems. The minimal path (MP, an edge set) set is one of the main tools used in measuring network reliability. A new node-based concept to find all MPs is proposed by simply searching all of the ordered node subsets with a time complexity O(ne n ), where n is the number of nodes. The proposed concept is implemented in a newly proposed node-based MP algorithm using depth-first search (DFS). Because O(m) = O(n 2 ), where m is the number of edges, the proposed node-based MP algorithm is theoretically more efficient than conventional edge-based algorithms, which all use time complexity O(n2 m ) to search for all MPs. Finally, a series of numerical experiments is implemented to test the performance of the proposed algorithm.

Reliability and Availability Evaluation for Cloud Data Center Networks Using Hierarchical Models

Modeling a cloud computing center is crucial to evaluate and predict its inner connectivity reliability and availability. Many previous studies on system availability/reliability assessment of virtualized systems consisting of singular servers in cloud data centers have been reported. In this paper, we propose a hierarchical modeling framework for the reliability and availability evaluation of tree-based data center networks. The hierarchical model consists of three layers, including 1) reliability graphs in the top layer to model the system network topology; 2) a fault-tree to model the architecture of the subsystems; and 3) stochastic reward nets to capture the behaviors and dependency of the components in the subsystems in detail. Two representative data center networks based on three-tier and fat-tree topologies are modeled and analyzed in a comprehensive manner. We specifically consider a number of case-studies to investigate the impact of networking and management on cloud computing centers. Furthermore, we perform various detailed analyses with regard to reliability and availability measures for the system models. The analysis results show that appropriate networking to optimize the distribution of nodes within the data center networks can enhance the reliability/availability. The conclusion of this paper can be used toward the practical management and the construction of cloud computing centers.

Efficient Enumeration of d‐Minimal Paths in Reliability Evaluation of Multistate Networks

A number of real‐world complex networks can be modeled as multistate networks for performance analysis. A multistate network consists of multistate components and possesses multiple different performance levels. For such a network, reliability is concerned with the probability of the network capacity level greater than or equal to a predetermined demand level d. One major method for multistate network reliability evaluation is using d‐minimal paths. This paper proposes an efficient algorithm to find d‐minimal paths. First, a new concept of qualified state vector is defined so as to fix a relatively smaller search space of d‐minimal paths, and a sufficient and necessary condition for a qualified state vector to be d‐minimal path is established. Then, the max‐flow algorithm and the enumeration algorithm are integrated to search for d‐minimal paths in the determined search space that is recursively divided into subspaces such that the searching efficiency can be increased as much as possible. Both analytical and numerical results show that the proposed algorithm is more efficient in finding all d‐minimal paths. In addition, a case study related to power transmission network is performed to demonstrate the implication of network reliability.

Availability, Performance and Reliability Evaluation for PV Distributed Generation

Nowadays, renewable energy resources play an important role in replacing conventional energy resources such as fossil fuel by integrating solar, wind and geothermal energy. Photovoltaic energy is one of the very promising renewable energy resources which grew rapidly in the past few years, it can be used to produce electric energy through photovoltaic process. The primary objective of the research proposed in this paper is to facilitate the increasing penetration levels of PV systems in the electric distribution networks. In this work, the PV module electrical model is presented based on the mathematical equations and was implemented on MATLAB to simulate the non-linear characteristics I-V and P-V curves with variable input parameters which are irradiance and temperature based on Riyadh region. In addition, the reliability evaluation of distribution networks, including distributed generators of solar photovoltaic (PV) with varying output power capacity is presented also. The Monte Carlo simulation algorithm is applied to test the distribution network which is RBTS Bus 2 and the same has been conducted on the original case of distribution network substation 7029 which is located at KSA Riyadh. The two distribution networks have been modified to include the PV’s distributed generators. The distributed generators contribute to supply a part of the load during normal mode and supply the entire load during component failure or failure of grid operation supply. The PV stochastic models have been used to simulate the randomness of these resources. Moreover, the study shows that the implementation and integration of renewable resources as distributed generations have improved the reliability of the distribution networks.

A new approach to heterogeneous wireless sensor networks reliability evaluation based on perception layer in internet of vehicles

Internet of vehicles (IoV) is a typical application of internet of things in the field of traffic. Heterogeneous wireless sensor network (HWSN) offers the technical support for perceiving and collecting the information on the internet of vehicles, but this technology faces tremendous challenges regarding the guarantee for data transmission reliability. This paper will study the HWSN reliability evaluation based on IoV perception layer and utilizes the object-oriented colored Petri net as the modeling tool for HWSN. On the basis of this model, this paper further explores the definition of HWSN reliability evaluation quantification and proposes a new approach to HWSN reliability evaluation quantification. At last, a simulation platform of HWSN is constructed to verify the effectiveness and feasibility of the proposed model and approach.