Reliability Of Network System Research Articles

Feasibility Analysis of Reliability Analysis Methods Applying in Air Traffic Control System

Air traffic control system plays a vital role of air traffic management system, of which reliability determines the service quality and supply level of air transportation. The structure of air traffic control system is considered, and an expression of reliability analysis is applied. A mount of methods including traditional reliability analysis and network system reliability analysis are introduced to demonstrate whether they are feasibility for reliability analysis of air traffic control system. This work can be used as reference and basic for air traffic control system, which is meaningful for ATM safety operation, system selection and response repair.

A Credit-Based System for Traffic Routing in Support of Vehicular Networks

Network routing has a great impact on the efficiency and reliability of the traffic network system in a real-world scenario. To date, achieving network-consistent performance is the main goal of many traffic network research studies. In this research, a mixed strategy game-theory model for network routing is proposed that discovers the optimal strategies that can be adopted by network route players in a network graph. This model has been validated by measuring the model outcomes using quantal response equilibrium (QRE) technique, which explores the players' noisy decisions by comparing the utilized optimal strategies with Nash equilibrium. The experimental results demonstrate that there is an equilibrium with a mixed strategy of a given network.

Unstructured Data Storage Function for 5G Core Network

In present broadband cellular network, all Network Functions are stateful, in which data related to user/connection/association is stored inside network elements itself. However sateful Network Functions cause multiple connection related problems in case of its failure and it needs a separate standby network to continue the process, which increases maintenance cost and reduces the reliability of network system. A technology called Unstructured Data Storage Function (UDSF) is introduced by 3GPP to resolve data storage issue with stateful Network Functions. In this paper the implementation of UDSF has been explained. UDSF has implemented with stateless principle to create a distributed system that can store structured and unstructured data related to each Network Functions on UDSF instead of in Network Functions. Usage of UDSF in 5G improves reliability of the network system.

Fault Detection and Isolation Methods in Subsea Observation Networks.

Subsea observation networks have gradually become the main means of deep-sea exploration. The reliability of the observation network is greatly affected by the severe undersea conditions. This study mainly focuses on theoretical research and the experimental platform verification of high-impedance and open-circuit fault detection for an underwater observation network. With the aid of deep learning, we perform the fault detection and prediction of the network operation. For the high-impedance and open-circuit fault detection of submarine cables, the entire system is modeled and simulated, and the voltage and current values of the operating nodes under different fault types are collected. Numerous calibrated data samples are supervised by a deep learning algorithm, and a fault location system model is built in the laboratory to verify the feasibility and superiority of the scheme. This paper also studies the fault isolation of the observation network, focusing on the communication protocol and the design of the fault isolation system. Experimental results verify the effectiveness of the proposed algorithm for the location and prediction of high-impedance and open-circuit faults, and the feasibility of the fault isolation system has also been verified. Moreover, the proposed methods greatly improve the reliability of undersea observation network systems.

Optimal Power Flow Management System for a Power Network with Stochastic Renewable Energy Resources Using Golden Ratio Optimization Method

An optimal operation system is a potential solution to increase the energy efficiency of a power network equipped with stochastic Renewable Energy Sources (RES). In this article, an Optimal Power Flow (OPF) problem has been formulated as a single and multi-objective problems for a conventional power generation and renewable sources connected to a power network. The objective functions reflect the minimization of fuel cost, gas emission, power loss, voltage deviation and improving the system stability. Considering the volatile renewable generation behaviour and uncertainty in the power prediction of wind and solar power output as a nonlinear optimization problem, this paper uses a Weibull and lognormal probability distribution functions to estimate the power output of renewable generation. Then, a new Golden Ratio Optimization Method (GROM) algorithm has been developed to solve the OPF problem for a power network incorporating with stochastic RES. The proposed GROM algorithm aims to improve the reliability, environmental and energy performance of the power network system (IEEE 30-bus system). Three different scenarios, using different RES locations, are presented and the results of the proposed GROM algorithm is compared to six heuristic search methods from the literature. The comparisons indicate that the GROM algorithm successfully reduce fuel costs, gas emission and improve the voltage stability and outperforms each of the presented six heuristic search methods.

State estimation of packet loss network based on dimension compression of measurement information

With packet loss, this paper proposes a method to compress the dimension of measurement information obtained by the sensor which is distributed in the wireless sensor network with single sensor and single communication link. Based on the minimum mean square error criterion, the state estimation method under the condition of dimension compression of measurement information is designed by using the improved Kalman filter when measurement noise and system noise are correlated. And the convergence condition of the estimation algorithm is analyzed. The simulation platform of matlab is used to verify the proposed estimation method. It is proved that the estimation accuracy of the measured physical quantity can be improved by using the dimension compression of measurement information estimation method, so as to improve the reliability of the whole network system.

The reliability analysis of k-ary n-cube networks

With the development of scalability and application of multiprocessor system, the components of the system possibly become faulty. It is desirable to know the reliability of the system. However, the exact reliability of a complicated network system is usually difficult to determine. A typical approach is to decompose the system into smaller ones based on a graph-theory model in which nodes are assumed to fail independently with known probabilities to measure the subsystem-based reliability, which is defined as the probability that a fault-free subsystem of a specific size is still available when the system has faults. In this paper, we use the probability fault model to establish upper and lower bounds on the subsystem-based reliability of k-ary n-cube networks, by taking into account the intersection of no more than five or four subgraphs. In addition, some numerical simulations of the subsystem-based reliability of k-ary n-cube networks are conducted.

End-to-End Reliability of Satellite Communication Network Systems

Satellite communication networks with onboard processing (OBP) satellites can provide high-speed data transmission rates and global service coverage with reduced propagation delays. This article proposes a means of analyzing the quantitative reliability of the satellite communication network systems. First, we identify the four major factors that affect the quality of network services: the OBP states, uplink channels, downlink channels, and uplink packet collision losses. Based on these four factors, a Markov model is derived to analyze the probability distributions of various network states. Analytic results show the network reliability with respect to the OBP structures and space radiation environments. The relationship between network reliability and throughput according to the packet traffic load is also quantitatively analyzed. Finally, based on the developed model, a method is suggested for iteratively updating the reliability distribution of network systems affected by changes in the four factors as well as network access time changes. The numerical results show an indication of the satellite network reliability to provide references whether adjusted elements of the four factors are eligible to sustain reliable end-to-end services.

Ecological environment fuzzy networking system protection based on optical fiber intelligent network

The optical fiber network has the characteristics of providing users with wider bandwidth and supporting the changing needs of more users. At the same time, the optical fiber network can also reduce the network infrastructure investment. The traditional Ad Hoc On-demand Distance Vector (AODV) algorithm does not consider the impact of node movement on the network, and the link disconnection frequently occurs during the routing process. The ant colony algorithm based on swarm intelligence only considers the unique factor of pheromone concentration to find the optimal path through multiple iterations, which will increase the complexity of the algorithm and affect the route establishment delay. In response to the above problems, this paper proposes a routing algorithm based on fuzzy logic. The algorithm can comprehensively consider the three factors of node location, mobility and signal strength, and greatly reduces the complexity of the algorithm. This paper gives a detailed definition of profust reliability of the Ethernet Passive Optical Network (EPON) system for distribution network communication and obtains the profust reliability parameters based on Monte Carlo simulation. After that, the reliability of profust under different networking modes was simulated, and the influence of network scale, component failure rate, component repair time and other parameters on the reliability of EPON networking profust was analyzed. The fuzzy probist reliability analysis method uses analytical methods, which are commonly used to deal with end-to-end reliability analysis problems and has certain limitations. Profust reliability analysis treats the system as a whole, which is more suitable for the reliability of complex end-to-multi-end systems.

Reliability evaluation and management of PetroChina's large-scale system of natural gas pipeline networks

To adapt to the current situation of large-scale and network development of China's natural gas pipeline industry, we must pay attention to the gas transmission support capability of the entire pipeline network system during its operation period and evaluate its reliability with respect to the fulfillment of transmission tasks. This study focuses on the safe and efficient operation and management of large-scale natural gas pipeline network systems, with the objectives of analyzing the reliability indicators, system reliability, unit reliability, reliability data, and reliability management framework of the pipeline network system. The above incentives have lain a foundation for future sustainable reliability management of large-scale systems of natural gas pipeline networks in China. Herein, the purpose, significance, and content of reliability studies on natural gas pipeline networks are discussed in detail at the system level. We establish a distributed step calculation model of physical pipeline network system reliability based on pipeline process simulation technology, which can simplify and rapidly calculate the reliability of the pipeline network/pipelines/station system. The reliability calculation model of the system was tested in a compressor station. According to the sequence of station yard-typical structure-basic circuit-equipment unit, the network topology structure was divided into reliability block diagrams of different levels from top to bottom, which we used to calculate the reliability of individual equipment from bottom to top. Finally, the reliability of the compressor station under different start-up and shutdown schemes was obtained. Overall, the discussed methods are promising and will provide technical and decision-making support for the safe operation of natural gas pipeline networks.

Game Theoretic Feedback Control for Reliability Enhancement of EtherCAT-Based Networked Systems

EtherCAT has become one of the leading real-time Ethernet solutions for networked industrial systems, where a reliable communication infrastructure is needed due to highly error-prone environments. However, existing work on EtherCAT mainly focuses on clock synchronization and timeliness improvement. The reliability of EtherCAT-based networked systems has largely been ignored. In this paper, we present a proportional integral derivative (PID)-based feedback control scheme that aims at enhancing reliability of networked systems under timing and system resource constraints. Instead of retransmitting data upon error detection, we use forward error control technique based on inequality of arithmetic and geometric means to achieve the required system reliability at a low deadline miss rate of messages. We further optimize the forward error control technique and design a fast and fair error resilient mechanism by using a cooperative game. In addition to reliability enhancement, our PID-based error control scheme can also improve the stability of a system in terms of deadline miss rate in the presence of burst errors. Simulation results show that the proposed scheme can achieve reliability enhancement of up to 91% compared to benchmarking methods.

An Improved Genetic Algorithm for Optimal Layout of Flow Meters and Valves in Water Network Partitioning

The paradigm of “divide and conquer” has been well used in Water Distribution Systems (WDSs) zoning planning in recent years. Indeed, Water Network Partitioning (WNP) has played an irreplaceable role in leakage control and pressure management; meanwhile it also has certain drawbacks, such as reduction of the supply reliability of the pipe network system and increased terminal dead water, as a result of the closure of the pipe section. In this paper, an improvement is made to the method proposed by Di Nardo et al. (2013) for optimal location of flow meters and valves. Three improvements to the genetic algorithm are proposed in this work for better and faster optimization in the dividing phase of WNP: preliminary hydraulic analysis which reduces the number of decision variables; modifications to the crossover mechanism to protect the superior individuals in the later stage; and boundary pipe grouping and mutation based on the pipe importance. The objective function considers the master–subordinate relationship when minimizing the number of flow meters and the difference of hydraulic state compared to original WDS. Another objective function of minimizing the deterioration of water quality compared to original WDS is also evaluated. The proposed method is applied for the WNP in a real WDS. Results show that it plays an effective role in the optimization of layout of the flow meters and valves in WNP.

An Analytical Model for Rank Distribution in Sparse Network Coding

Random linear network coding is a promising coding scheme to increase the robustness and reliability of network systems. However, one of its major drawbacks is the high computational complexity. Sparse Network Coding (SNC) was proposed to reduce the computational complexity at the expense of larger communication overhead. However, the performance evaluation of SNC is still a major research topic due to an inaccurate expression for the behavior of sparse matrices. In this letter, we present two approximation models to analyze the probability distribution of the rank of sparse matrices. We use our models to derive the average number of required transmissions in the SNC scheme. Our results show that the proposed models predict the rank of sparse matrices and the average number of transmissions with a maximum deviation of 4% and 6%, respectively.

Hybrid Energy Storage Capacity Allocation Method for Active Distribution Network Considering Demand Side Response

In the power market, the reasonable configuration of the energy storage (ES) system can improve the reliability and economy of the active distribution network system. First, the stepped multiprice and multitime demand side response (DSM) model is proposed. Second, the energy type and the power type energy storage device are used together. The supercapacitor device is used to stabilize the fluctuation of the distributed power source. The lithium iron phosphate battery is used to reduce the power shortage rate of the load. At the same time, line loss is considered in the optimization goal. The location and capacity of the hybrid energy storage device are discussed. Finally, the time-of-use tariff policy is considered, the power compensation cost of the interruptible load is calculated, the DSM policy is introduced, and the joint planning with the ES system is realized.

Research on optimal operation of distribution network with electric springs

The electric spring (ES) is a kind of electric device used for energy buffering, based on voltage and power management. ES transfers the voltage (or energy) fluctuation in the main bus to the non-critical load (NCL), stabilises the main voltage for critical load, and actively adjusts the power consumption of the NCL to achieve regulation goals of distribution network with wide voltage operational range of NCL. With lots of intermittent and fluctuating renewable energy resources into the energy Internet, the smart load integrated with the ES will play a greater role in the optimal operation of the distribution network. Here, the power flow optimal model of distribution network with the ES is proposed. Under different load levels, the flexible regulation of ES can reduce the overall voltage drop and optimise the operation of distribution network. The benefits of ES for the optimisation of distribution network are verified based on an improved IEEE 33-node case. Numerical results show that the ES relieves the voltage drop of the distribution network and improves the reliability of distribution network based on the interaction between the ES and NCL. The overall energy efficiency and reliability of the distribution network system are improved.

Fault Diagnosis of Gas Pressure Regulators Based on CEEMDAN and Feature Clustering

Gas pressure regulators are widely applied in natural gas pipeline networks, correspondingly, establishing an efficient fault diagnosis approach of regulators plays a critical role in optimizing the safety and reliability of pipeline network systems. In our paper, considering that the outlet pressure signals of gas regulators are nonstationary and nonlinear, we propose a fault diagnosis approach combining a complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and fuzzy c-means (FCM) clustering to classify three typical faults of gas regulators. First, we propose to apply the CEEMDAN approach for decomposing intrinsic mode functions (IMFs). Then feature vectors of the typical faults are established by Hilbert marginal spectrum (HMS) of IMFs. Finally, we adopt cluster centers and feature clustering algorithm to distinguish the types of faults. The experimental results indicate the high performance of the present fault diagnosis approach. The membership degrees of test samples obtained from the CEEMDAN algorithm are optimized to be within 0.9 to 1.

Reliability Analysis of Network Based on the Traffic Correlation

In order to analyze the influence of the traffic correlation parameter ‘r’ on the reliability of the complex network system, the characteristics of network traffic arrival is analyzed based on a sine wave with random phase, and a network packet loss rate analysis model is built based on the queuing theory to analyze the network system reliability. The results indicate the greater the traffic correlation parameter ‘r’ is, the lower the reliability of network system will be. To improve the reliability and resource utilization of network system, the effective balance of the relevant parameter ‘r’ should be achieved at the same time.

Reliability Assessment of Distribution Network System Considering Output Uncertainties of Distributed Generators

In view of the effect of DGs uncertainty on the reliability of the distribution network system, an integrated Markov model is put forward to evaluate the reliability of distribution network, considering the randomness of DG, DG mechanical failure rate and starting/switching refuse rate and other factors; In view of the randomness of the output of photovoltaic power, using the Cornish Fisher expansion method to generate the standard normal distribution of sample space in order to further analysis the effects of illumination intensity correlation coefficient of distribution system reliability. Through the simulation analysis of BUS6 IEEE-RBTS system, the simulation results show that the reliability of distribution network system is closely related to the distributed power access point, the DG capacity and the DG output correlation coefficient.

Reliability Evaluation of Power Distribution System with Reliability Index Assessment (RIA)

Distribution network system reliability is a measure of the level of service of the system of electricity supply to consumers. This study aimed to get some reliability index value of the electricity distribution network system at PT PLN (Persero) APJ Bandung, namely the failure rate, the average output time, the average annual unavailability, SAIFI, SAIDI, CAIDI, ENS and then AENS. These results will be used as a reference for determining the level of reliability of the system. Search reliability index value itself is done by way of basic data recap interference on each unit in the network (UPJ) and then calculating the index of reliability by using formulas reliability index. The results of this study, the value of reliability indices SAIFI on the system 2.02 disorders / customer / year with a target of 1.27 disorders / customer / year, while the reliability index SAIDI on the system 0.28 hours / customer / year with a target of 0.21 hours / customer / year, with these results show electric power distribution network system of PT PLN (Persero) APJ Bandung could not reach the target reliability especially SAIFI and SAIDI. The results of this study are also expected to give an idea of the level of system reliability of electric power distribution network PT PLN (Persero) APJ Bandung.

Niezawodność współzależnych sieci z uszkodzeniami kaskadowymi

The reliability of network systems of various structures has been studied by many researchers. However, most of the works just consider the reliability of a single network system. In practice, different networks may be interdependent such that the failure in one network may result in the failure in another network. The cascading failures have been shown to be catastrophic by some researchers. However, the quantitative evaluation for the reliability of interdependent networks has not been proposed. In this paper, a multi-valued decision diagram based approach is presented to evaluate the reliability of interdependent networks. Illustrative examples are proposed to demonstrate the application of the framework.