Average Restoration Time Research Articles

Increasing resilience and selection of a strategy for restoring transport networks in extreme natural processes

Aim. The development of an approach to increasing resilience by selecting strategies for restoring transport networks affected by extreme natural processes. Methods. This study evaluates the dynamics of extreme natural processes, specifically exogenous geological processes that can that can disrupt transport networks. It includes as framework for assessing the sustainability and restoration of transport networks under climate risk factors. Strategies for restoring the transport network were formulated. Results. The formulated strategies enable network modeling of transport network topology, which can be represented as an undirected weighted graph with a set of nodes and edges. The proposed model allows determining the most effective strategy for quickly restoring the connectivity of the transport network by determining the optimal sequence of restoration for repairing road sections, considering restoration time. The efficiency of restoring damaged sections of the transport network is expected to decrease as the share of the restored network increases. Therefore, it is crucial to estimate the necessary extend of network restoration to perform the necessary extent of network restoration to support emergency and urgent tasks by RSChS formations in specific areas. Conclusion. The analysis and assessment of alternative solutions for restoring the sustainability of transport networks considers the complexity of tasks under climate risk factors, such as extreme natural processes. In some cases, the RSChS problems do not require complete network restoration, unlike the tasks solved by the transport industry. This work aims to develop a framework for assessing restoration strategies, identifying the features of each of the considered strategies under uncertainty, and increasing operational sustainability. The proposed approach is flexible, allowing decision makers to assess various priorities during a specific natural emergency in a certain area, such as average recovery time, process efficiency, and uncertainty levels, when choosing the most desirable strategy. It is assumed that the average recovery time does not differ significantly among strategies for full network restoration. However, for partial restorations necessary for RSChS tasks, the average restoration time depends on the chosen strategy.

Post-Disaster Resilience Optimization for Road–Bridge Transportation Systems Considering Economic Loss

After a disaster, the recovery sequence of damaged bridges in a road–bridge transportation system greatly influences system restoration time and total economic loss. In this paper, the skew of recovery trajectory is introduced to evaluate the average restoration time, and the total economic loss is extended to consider the indirect loss, such as the energy consumption of detours or the emergency service fee. So, the post-disaster resilience optimization model is constructed by minimizing the total economic loss. The improved genetic algorithm is developed to obtain the optimal recovery scheme for damaged bridges by considering the recovery sequence and repair modes. The composition and influence factors of total economic loss are analyzed through three experiments. The experimental results show that the indirect loss accounts for approximately half of the economic loss, while the higher price of emergency service promotes the reduction of indirect loss using the expedited modes to repair damaged bridges. Moreover, to minimize the total economic loss, it is essential to design the optimal recovery scheme (repair sequence and repair mode) wisely to balance the conflicts between indirect loss and direct loss.

Reliability Enhancement on Distribution System Using Modified Multi-Objective Particle Swarm Optimization Technique

This research paper introduces an innovative approach for optimizing the placement of fault indicators (FIs) within electric distribution systems. The primary focus is on addressing how the presence of existing protection and control devices affects the time it takes to restore service to customers in the event of a fault. Unlike conventional FI placement methods, this extended approach considers the uncertainties associated with automatic switching and introduces a novel technical objective function known as the Customers' Average Restoration Time Index (CARTI). To tackle the complex task of multi-objective optimization, a solution approach has been devised, with the goal of simultaneously minimizing both economic and technical objectives. This methodology harnesses a Multi-Objective Particle Swarm Optimization (MOPSO) algorithm and incorporates a Modified Particle Swarm Optimization technique to select the most suitable solution from the set of Pareto optimal solutions generated. The proposed method's effectiveness is demonstrated through its application in two scenarios: firstly, in the context of bus number four within the Roy Billinton test system (RBTS4), and secondly, in a practical real-life distribution network. The study assesses technical objectives, specifically the System Average Interruption Duration Index (SAIDI) and CARTI, providing insights into the method's practical utility and its capacity to enhance FI placement for improved distribution system performance.

Определение современных показателей надежности воздушных линий электропередачи 0,4-110 кВ

Reliability indicators for 0.4-110 kV overhead transmission lines need to be adjusted due to the lack of data on current values of reliability indicators for power system equipment. The authors’ analysis of offi cial statistical data on the number of emergency and scheduled outages in the branches of PJSC “Rosseti Tsentr” and “Rosseti Tsentr i Privolzhye” revealed deviations of the reliability indicators of electrical equipment of power systems and power grids from those presented in RD34.20.574. Also, the analysis showed that the standard presented no values of average downtime for planned outages of 0.4 kV and 6-10 kV overhead power lines. Reliability values of 0.4-110 kV overhead power lines were determined. Failure rate of 0.4 kV overhead lines made 6.2 to 7.04 year-1/100·km, of 6-10 kV overhead lines - 5.27 to 8 year-1/100·km. The “Orelenergo” branch, a failure fl ow of 35 kV overhead lines was 0.57 year-1/100·km, and 110 kV overhead lines - 2.83 year-1/100·km. The calculated value of the average restoration time for 0.4 kV networks was 1.88 h; for 6-10 kV networks - 3.1 h; 35 kV - 6.8 h; 110 kV - 9.5 h. The estimated average number of intentional outages for 0.4 kV networks was 0.1 year-1; for 6-10 kV networks 0.72 year-1; for 35 kV networks 0.4 year-1; for 110 kV networks 0.51 year-1. The average idle time of 0.4 kV overhead lines and 6-10 kV overhead lines amounted to 13.6 hours and 10 hours, respectively. The calculated average downtime of 35 kV overhead lines and 110 kV overhead lines amounted to 24.7 hours and 37.6 hours, respectively. The received data specify modern reliability values of electric 0.4-110 kV networks that can be used when planning measures on developing networks and reconstructing them.

Influence of the aging factor on the reliability of agricultural machinery

In the course of time a number of machine significant changes related to machine aging occur. The reasons for these changes are quite diverse. They are inevitable and irreversible in the time process of a gradual transition of the machine to a lower qualitative state. The article contains the data about the change in the indicators of no-failure and repairability of tractors (average restoration time) in the before-repair and between-repairs periods, which should be considered as a result of their aging. Data on the ratio of the lifetime of units and parts indicate the decisive role of the aging factor, but the lifetime can be strongly influenced by the assembly technology and the main thing - the run-in of parts. The degree of the aging of a machine can be estimated by reducing the lifetime of components, MTBF, machine productivity, etc., in the form of an aging factor, Kc. It shows how many times the lifetime of the part replaced in the machine is less than the nominal lifetime of the original part. The MTBF of the ageing machine is less than that of the new machine, or the labor input for the restoration of the old machine is greater than that of the new machine. By determining the aging rate of the parts to be replaced over the time interval under consideration, we constructed an aging function. The aging process of agricultural machinery was evaluated by the time and moment of resistance to unscrewing the uncoated threaded joints with a service life of 0.2 to 4 years. According to the obtained distribution functions, the average time increases with increasing service life, and the moment of resistance to unscrewing approaches the maximum values. With a service life of more than 4 years, the number of non-disassembled bolt connections, which break at the moment of unscrewing, increases, and the maintenance time also increases. The dynamics of the aging factors of threaded connections can be represented in the form of quadratic functions.

MODERN TRENDS IN THE TREATMENT OF ACUTE ADHESION IN INTESTINAL OBSTRUCTION

Summary. Aim. To perform the modern tactics of acute adhesive obstruction (AAO) treatment.
 Materials and methods. The basis of the work is the analysis of the results of treatment of 38 patients hospitalized in an urgent order to the surgical department with the clinic AAO.
 Results. 20 (52.6 %) patients with the background of conservative therapy, the phenomenon of intestinal obstruction was regressed. Repeated hospitalization during the year with the hospital was required by AAO 2 (5.3 %) patients. Laparoscopic adhesion was performed 4 (10.5 %) patients whose average intestinal restoration time was (1.8±1.2) days, and the duration of postoperative inpatient treatment was (5.1±1.3) days. Open surgical interventions were performed 14 (36.8 %) patients, in whom the period of restoration of the intestine function was (3.8±1.5) days, and the duration of postoperative treatment was (10.1±1.2) days.
 Conclusion. Conservative therapy is effective in 52.6 % of patients. Laparoscopic adhesion is indicated in the absence of peritoneal symptoms, if ≤ 2 laparotomies were noted in the history, with a peritoneal index of adhesion ≤ 9 points.

Fast restoration of geometric details of automobile castings scanned by RGB-D sensor

The depth data of automobile castings obtained by RGB-D sensor are usually combined with noise, the classical regularization method can eliminate the noise efficiently. Yet the regularization step is too time-consuming to reconstruct the geometric details of automobile castings efficiently. Given this, we present a fast method called fast restoration of automobile castings (FRAC) to restore the geometric details of automobile castings in fast manner. First, the implicit surface data is extracted from globally aligned RGB-D images, the voxel data structure is extended to index and process the implicit surface in real time. Then, an inverse shading formula is constructed to compute TSDF (truncated signed distance field) values of casting surfaces quickly, and an objective function is designed to optimize the geometric details of casting surfaces in real time. Finally, a GPU-based Gauss–Newton solver is used to accelerate restoration of castings further. The defective casting models scanned by RGB-D sensor are quickly refined to a complete model with better accuracy. Experimental results show that with respect to the sampled automobile castings which include 359,470 points in average, the average optimization time reaches 0.66 s per frame, the average restoration time is about 6.48 s. Computing TSDF requires only about 34.8 MB GPU caches in average. FRAC is able to restore the geometric details of automobile castings in real time.

Distribution System Reliability with Distributed Generation Based on Customer Scattering

This paper presents the reliability improvement with effect of customer scattering on distribution system with Distributed Generation (DG). The test system is studied in six different cases based on different customer scattering patterns. Each customer scattering case is analyzed for finding the reliability indices of the distribution system without DG, and with installation of DG at various locations along the feeder. In addition, the algorithm for assessment of average restoration time of load point is presented when DG is installed. The proposed algorithm is tested on a simple system consists of nine load points. The reliability improvement is measured by reliability indices that include SAIFI, SAIDI, CAIDI, ENS and AENS. On the other hand it provides some useful conclusions such as the customer scattering and restoration time effect the optimal location of DG in terms of system reliability.

Fault Indicator Deployment in Distribution Systems Considering Available Control and Protection Devices: A Multi-Objective Formulation Approach

This paper introduces a multi-objective fault indicator (FI) placement method in electric distribution systems. The prevalent FI placement problem formulation is extended by considering effects of existing protection and control devices on customers' restoration time. Moreover, the customers' average restoration time index (CARTI) is proposed, as a new technical objective function with respect to uncertainties of automatic switching. Furthermore, a multi-objective solution approach is developed to simultaneously minimize indispensable economic and technical objectives. The resultant optimization problem is solved through a multi-objective particle swarm optimization (MOPSO) based algorithm, accompanied by a fuzzy decision making method to select the best result among the obtained Pareto optimal set of solutions. Assuming SAIDI and CARTI as technical objectives, the proposed method is applied to bus number four of the Roy Billinton test system (RBTS4), as well as a real-life distribution network with about 5500 customers, followed by a discussion on results.

Optimal stochastic fault tracking for rural electrical distribution networks via emergency brigades

This article presents the results obtained when applying a new strategy for finding faults in rural distribution systems. This paper proposes a working protocol for the minimization of the average restoration time via the emergency brigades. The methodology involves two stages: (i) discrimination and (ii) tracking of electric faults. The process uses only the principal distribution substation recorded data to construct the “short-circuit current ranges” of fault locations (zoning). The tracking is a probabilistic optimization process which uses the failure probability, the inspection time and the transit time of each line (the three basic ideas used by the emergency brigades to locate faults). The validity and robustness of the model is verified with real short-circuit situations. According to the results, the proposed strategy provides a plan of action to emergency brigades reducing, significantly, the time and mileage used to find the point where the failure occurred.

Reliability Improvement of a Radial Feeder Using Multiple Fault Passage Indicators

For a fixed number of customers, reliability of a distribution network can be improved by reducing the duration of interruptions by faster restoration techniques. After occurrence of a fault, the average restoration time of a load point depends on average fault location identification time and repair time or switching time. The Fault Passage Indicator is a device that helps the utility to restore the supplies more quickly by reducing the time that an operating crew needs to travel around the network in search of a fault. To achieve a high degree of reliability for a given number of FPIs, it is necessary to decide the best locations of FPIs in a distribution network. In this paper, the effect of installing multiple FPIs on the reliability of a radial feeder is discussed and is implemented on an 11 kV, 2 MVA Indian utility radial feeder for five different configurations.

Restoration performance study of k-shortest disjoint paths in WDM optical networks

Many researchers have proposed restoration techniques incorporating the concept of k-shortest disjoint paths in survivable WDM (Wavelength Division Multiplexing) optical networks, but without considering network performance and network costs simultaneously. In this paper we need to carefully look into how well the concept of shortest disjoint paths is incorporated for given objective functions. Seven objective functions and four algorithms are presented to evaluate the concept of k-shortest disjoint paths for the design of a robust WDM optical network. A case study based on simulation experiments is conducted to illustrate the application and efficiency of k-shortest disjoint paths in terms of following objective goals: minimal wavelengths, minimal wavelength link distance, minimal wavelength mileage costs, even distribution of traffic flows, average restoration time of backup lightpaths, and physical topology constraints.

Routing pre-configuration for fast and scalable path restoration in DWDM networks

In high-speed WDM optical networks, failure recovery is a critical issue as a single element failure in the network will result in the interruption of multiple services. Distributed path restoration is preferable for its high flexibility and efficient resource utilization. However, with the development and maturity of Dense Wavelength Division Multiplexing (DWDM) technology, the resource contention problem arises when simultaneously restoring a large amount of services initiated from many uncoordinated source nodes. This will degrade network performance and result in long service recovery latency. In this paper, we present the Routing Pre-Configuration (RPC) scheme for fast and scalable path restoration in DWDM networks, where pre-failure configuration and post-failure signaling are demonstrated. We compare it with the previous contention resolution approaches and the simulation results prove its improvement in restoration blocking probability and average restoration time.

Dynamic service-level-agreement aware shared-path protection in WDM mesh networks

The notion of service level agreements (SLA) has been proposed to capture qualitatively and quantitatively defined performance contracts between service providers and their customers. How to provision satisfiable connections for customers according to their SLA parameters to avoid penalty as well as minimizing cost is one of the main concerns for a service provider. Connection reliability and restoration time are two important SLA parameters for a customer, and should be carefully considered in survivable wavelength-division-multiplexing (WDM) networks. A sound scheme should guarantee customers’ reliability and reduce restoration time while benefiting a service provider in resource efficiency. Under the SLA constraints and the assumption of single link failure, we first investigate a partial link-disjoint protection (PLDP) and analyze its availability and average restoration time. We then propose a dynamic constraint shared path protection (DCSP) algorithm in WDM mesh networks. Based on the basic ideas of the K-shortest path algorithm and PLDP, DCSP can provide differentiated services for customers according to their SLA parameters while being favorable for reducing average restoration time and optimizing resource utilization. Simulation results show that DCSP can efficiently guarantee the specific SLA requirements of customers with a slight increase in the blocking probability while still achieving spare resource sharing and restoration time optimizations.

Evaluation of restoration techniques incorporating optimal principle in WDM optical networks

Numerous researchers have proposed restoration techniques incorporating the concept of shortest disjoint paths in Wavelength Division Multiplexing (WDM) optical networks. The concept of shortest disjoint paths that obeys the strong optimal principle and the weak optimal principle is very important because shorter wavelength mileage including optical fiber distances is a dominant factor for the design of a survival WDM optical network. Even if restoration techniques incorporating the concept of shortest disjoint paths are faster, simpler, and easier than any other restoration techniques, we need to evaluate how well the concept of shortest disjoint paths is incorporated for the design of a survivable WDM optical network. In this paper, topology dependencies related to the concept of shortest disjoint paths are first developed. Then, seven objective functions that yield objective goals significant to the optimal design of a survivable WDM optical network are proposed and mathematically formulated. Finally, we develop ASDP (Near-Optimally Annealed k-Shortest Disjoint Path Restoration) and BBD (Branch-and-Bound with Dynamic Programming Principle) restoration algorithms that examine the proposed objective functions. Numerical results by experimenting ASDP and BBD algorithms show that the concept of shortest disjoint paths yields the best performance in terms of total and average restoration time. However, the concept of shortest disjoint paths does not seem to be an optimal technique in terms of significant optimal objective goals: minimal wavelengths, minimal wavelength link distance, minimal wavelength mileage costs, and even distribution of traffic flows.

Modeling and performance study of restoration framework in WDM optical networks

Restoration techniques available in literature have not addressed their performance in terms of network performance factors and network costs. However, restoration must consider a number of network performance factors and network costs simultaneously. We evaluate existing restoration models and their performance in an attempt to verify their performance and efficacy based on literature. Our research has found not only inefficiency in some of these methods, but a general incompatibility. Consequently, we propose a restoration framework and examine its performance. The proposed restoration framework consists of seven objective functions and three algorithms. Three algorithms are developed for restorable routing and wavelength assignment. Seven objective functions yield their own objective goals significant to the optimal design of a survivable WDM (Wavelength Division Multiplexing) optical network. Three algorithms are exploited to measure the performance of objective functions. They are DCROS (Deep Conjectural Reinforced local Optimal Search), HRM (Hybrid Restoration Method), and RWWA (Random Walk-based Wavelength Assignment) algorithms. The DCROS algorithm finds a set of disjoint lightpaths for a given objective function. Each of those disjoint lightpaths can be used for a primary lightpath and a backup lightpath. The HRM improves results generated by the DCROS algorithm. The RWWA algorithm assigns wavelengths to primary and backup lightpaths. Numerical results obtained by experimental evaluation of proposed objective functions and algorithms confirm that MTLF (objective function of Minimizing Total Lightpath Flows with multi-objective goals) among objective functions yields multiple near optimal objective goals: minimal wavelengths, minimal wavelength link distance, minimal wavelength mileage costs, even distribution of traffic flows, total and average restoration time of backup lightpaths, and escape from physical topology constraints.

Path vs. subpath vs. link restoration for fault management in IP-over-WDM networks: performance comparisons using GMPLS control signaling

We investigate three restoration techniques (path, subpath, and link restoration) for fault management in an IP-over-WDM network. We have implemented all of these techniques on the ns-2 simulation platform using generalized multiprotocol label switching (GMPLS) control signaling. These techniques can handle practical situations such as simultaneous multiple fiber failures, which are difficult to design for and recover from by nonrestoration techniques. We then present performance measurement results for the three restoration techniques by applying them to a typical nationwide mesh network running IP over WDM. We investigate interesting trade-offs in the performance of the restoration techniques on restoration success rate, average restoration time, availability, and blocking probability.

Reliability Cost/Worth Assessment of Distribution Systems Incorporating Time Varying Weather Conditions and Restoration Resources

This paper presents a time-sequential simulation technique incorporating the effects of weather conditions and restoration resources in reliability cost/worth evaluation of distribution systems. Time-varying weight factors (TVWF) are introduced to represent the effects on component failure rates and restoration times of weather and available restoration resources. The average failure rate is combined with the TVWF to create time-varying failure rates (TVFRs) for each component. The average restoration time is combined with the TVWF to create time-varying restoration times (TVRTs). Studies conducted in a test distribution system show that the TVFR have large impacts on the interruption costs of frequency-sensitive customers and slight effects on others. The TVRT have significant effects on the indices for all the customers. It is therefore important to consider TVRT in evaluating reliability cost/worth of network reinforcement.

Efficiency of storage by means of accumulating storage tanks

The reliability and efficiency of cryogenic storage tanks and their liquefying and refrigerating systems were studied in the context of a helium cyrogenic system. The purpose was to assess the feasibility of adding such accumulators to production lines in chemical and petroleum processing to guarantee continuous operation of the line. Reliability was assessed by using such parameters as production achieved before failure, production at failure, and the time required for restoration. The probability of trouble-free operation as a function of the unit restoration time was determined. It was established that in the case of an exponential distribution function the average restoration time was independent of the amount of product in the tank. Tests show increased reliability depending on the time when the system can be supplied from a spare storage tank in the case of failure and repair of the liquefying unit.