Remote Backup Research Articles

Optimizing Backup Optical-Network-Units Selection and Backup Fibers Deployment in Survivable Hybrid Wireless-Optical Broadband Access Networks

Survivability is one of the key issues in hybrid wireless-optical broadband access networks (WOBAN) since the single segment failure can cause huge data loss. The single segment failure refers to a scenario where all optical-network-units (ONUs) are disconnected with the optical line terminal (OLT). Previous schemes focus on protecting WOBAN against single segment failure by deploying backup fibers. However, previous schemes suffer from two key problems. First, they ignore optimizing the selection of backup ONUs, which determines the cost of recovering the traffic interrupted by the failure. Second, they underutilize the residual capacity of segments, thus requiring higher backup fibers cost. In this paper, we propose a new and efficient scheme, called Optimizing Backup ONUs selection and backup Fibers deployment (OBOF), to enhance the survivability of WOBAN against the single segment failure. Our OBOF is composed of two consecutive steps, backup ONUs selection and backup fibers deployment. In the first step, aiming to minimize the cost of recovering the traffic interrupted by the failure, the simulated annealing (SA) algorithm is customized to optimize the selection of backup ONUs. In the second step, most importantly, an enhanced greedy cost-efficiency (EGCE) algorithm is proposed to optimize the deployment of backup fibers. Our EGCE consists of a novel remote backup segment (RBS) method, which can efficiently utilize the residual capacity of the segments, and a Bound on Length of Backup-optical-path (BLB) method, which limits the increase in recovery time induced by RBS. Extensive experimental results demonstrate that our OBOF scheme outperforms the previous schemes significantly, especially in the scenario of higher traffic demand.

Experimental Investigation of H 2 Generator and PEM Fuel Cell as a Remote Area Back-Up Power

Abstract A reliable power is paramount and loss of power to communication equipment can mean loss of service to customers and loss of millions of dollars to companies. When the grid power is unavailable in remote areas there are variety of back-up electrical power systems like valve-regulated lead acid (VRLA) battery systems, engine-generator sets, ultra capacitors, flywheels, and new battery technologies that strive to provide back-up power. Hydrogen Energy and fuel cell technology compete with traditional technologies meeting back-up power requirements in stationary applications. Recent collaboration between Victoria University, Sustainable Energy Fuel Cells Australia (SEFCA) and Acta Energy has resulted in thorough laboratory testing for H 2 generation and data compilation of fuel cells in a back-up power operation in Power Systems Research Laboratory at Victoria University. The authors of this paper suggests that the use of EL100 H 2 generator and T-1000 1.2 kW PEMFC Power Generation System is capable to compete with traditional technologies to offer back-up power when there is no base load or PV or wind power. This paper presents the planning of laboratory testing, analysis and evaluation of the laboratory results. This paper also highlights the benefits of PEMFC system, EL100 H 2 generator and ReliOn's T-1000 PEMFC system. Currently it is expensive to run distance trucks requiring several site visits per year in order to refill the diesel or even carrying H 2 bottles to a rural site. This system generates H 2 on-site and can be implemented as a back-up power in telecommunication system like the Australian National Broadband Network (NBN) where there will be need for reliable back-up power supply since NBN will be rolling out several hundred points of presence (POP's).

High-speed non-unit transmission line protection using single-phase measurements and an adaptive wavelet: zone detection and fault classification

This work describes a transmission line protection scheme with two protection functions: directional zone and fault classification. The proposed scheme requires no information from remote ends and uses current measurements of only one phase of the three-phase systems for determining the fault direction, the faulted line and the fault type. Information concerning the high-frequency components of transient current signals is extracted with discrete wavelet transform (DWT) by using an adaptive wavelet, which has been specifically designed for relaying purposes, as analysis filter. After that, Bayesian linear discriminant analysis is employed for data classification. The present work highlights that the adaptive wavelet used here presents advantages for transmission line protection rather than predefined mother wavelets. Results demonstrate that the proposed scheme effectively distinguishes the faulted zone, the fault direction and the fault type. Therefore it offers primary protection to total line length, remote backup protection for the next transmission line and also the possibility to implement single-pole tripping. Current signals of roughly 2 ms are analysed then the proposed methodology can be implemented in high-speed protection schemes for extra- and ultra-high voltage (EHV/UHV) networks.

Adaptive load blinder for distance protection

This paper proposes a novel adaptive load blinder for distance protection. A distance relay can provide remote backup protection by zones 2 and 3, but it may mal-operate under heavy loading conditions and cause cascading trips in the network, which could further lead to a widespread blackout. To prevent cascading outages, load blinders or load encroachment elements are generally used to block the distance relay when there is heavy load in the system. However, these elements are not always able to discriminate heavy loading conditions from fault conditions, especially for heavy loads with low power factors or faults with fault resistance. This paper presents a novel load blinder scheme for distance protection by using artificial neural network (ANN). Test results show that the proposed ANN-based load blinder scheme is able to discriminate between different heavy loads with a wide range of power factors and different faults with fault resistance.

Secure Remote Backup Protection of Transmission Lines Using Synchrophasors

We consider the problem of detecting a fault on a transmission line from the residual vector of a synchrophasor state estimator (SynSE). For a transmission line under fault, we identify six operating modes depending upon location of the phasor measurement units (PMUs). We show that in five operating modes, the fault is seen in the residual vector while in one mode, the fault will not reflect in the residual vector. The analysis leads us to propose a remote backup protection scheme for supervised zone-3 operation of distance relays. In case of inadequate PMU penetration in the system, the implementation of SynSE can even be restricted to a small subsystem of critical lines.

Research of Log System for IP Network Storage

As there are many kinds of logs and format, and it is difficult to view and manage the logs, how to view and manage the logs efficiently and effectively has become a crucial issue. At the same time, it is important for the log manager to get the record of user operation and system running, how the log manager view and manage these records proper is of particular importance. However, design and realization of the log management system for IP network storage (StorLog) has solved these problems. StorLog supports kinds of logs, like system logs, web logs, file system logs, storage logs and etc. It can protect log files effectively, rotate logs automatically, support remote backup and recovery, and support advanced research. The practical application shows that StorLog can not only view logs efficiently and manage and storage system logs conveniently, but also it is simple in function and easy to install and use, therefore, it greatly improves work efficiency and resource utilization of system.

Fourteen Year Follow-up after Direct Percutaneous Intervention (DPCI) with Remote Surgical Backup for Anterior ST elevation myocardial infarction (STEMI)

Background: We performed DPCI for acute STEMI between June 1995 and August 1998 with backup from a cardiac surgery centre 362 km away. DPCI procedures were provided from 8 am to 8 pm.

Fourteen Year Follow-Up After Direct Percutaneous Intervention (DPCI) with Remote Surgical Backup for Anterior ST Elevation Myocardial Infarction (STEMI)

Background: We performed DPCI for acute STEMI between June 1995 and August 1998 with back-up from a cardiac surgery centre 362 km away. DPCI procedures were provided from 8am to 8pm. Methods: In this analysis, we compared patients who were enrolled in the Post Myocardial Infarction Study and who were treated for first anterior STEMI by DPCI (n= 46) or thrombolysis (TS, n= 108). Patients were excluded from this analysis if they presented in cardiogenic shock, had a past history of myocardial infarction, or received rescue PCI. Results:Medianagewas61yrs (48–68, 25–75thcentile) in theDPCI groupand63 yrs (53–70) in theTSgroup (p= 0.13) and 89% and 75% were men (p= 0.05). Two patients were transferred electively to the surgical centre for observation after PCI but neither received cardiac surgery. Cumulative mortality is presented in the Kaplan–Meier figure below, 19

Link-alike

Asymmetric broadband connections in the home provide a limited upstream pipe to the Internet. This limitation makes various applications, such as remote backup and sharing high definition video, impractical. However, homes in a neighborhood often have high bandwidth wireless networks, whose bandwidth exceeds that of a single wired uplink. Moreover, most (wired and wireless) connections are idle most of the time. In this paper, we examine the fundamental requirements of a system that aggregates upstream broadband connections in a neighborhood using wireless communication between homes. A scheme addressing this problem must operate efficiently in an environment that is: i) highly lossy; ii) broadcast in nature; and iii) half-duplex. We propose a novel scheme, Link-alike, that addresses those three challenges using opportunistic wireless reception, a novel wireless broadcast rate control scheme, and preferential use of the wired downlink. Through analytical and experimental evaluation, we demonstrate that our approach provides significantly better throughput than previous solutions based on TCP or UDP unicast.

Improvements of protective characteristics of automatic low-voltage circuit breakers

Suggestions on how to improve the protective characteristics of automatic low-voltage breakers, namely, to increase the sensitivity to remote short-circuits (faults), to raise the speed of selective protection, and to enhance the reliability by long-distance (remote) backup are considered. The use of the power function of a current to quickly identify the reason for a circuit disturbance and determine the rms current value of the current’s periodic component is grounded. Advantages of the use of the Joule integral as a criterion to selectively operate breakers are shown.

Identifying the Primary Fault Section After Contingencies in Bulk Power Systems

This paper deals with the problem of fault section estimation in electric power systems, undertaken at a control center level and using information about the operation of protection relays and circuit breakers. The developed methodology should be used after the occurrence of contingencies with definitive disconnections, and before beginning the process of network restoration. Due to the absence of an analytic formulation, the problem calls for the use of artificial-intelligence techniques, such as neural networks and expert systems. Neural networks are employed to model the protection systems, dealing with the uncertainties involved with relay and circuit-breaker operation messages. An expert system is used to complement the results provided by the neural networks, considering the network topology. The results show that the developed methodology is applicable to real large-scale power systems. In addition, it is capable of noise suppression in relay and circuit-breaker trip messages, treats multiple faults naturally, and infers a solution even in cases when remote backup protection action occurs.

Overview of Electron Cyclotron Heating and Electron Cyclotron Current Drive Launcher Development in Magnetic Fusion Devices

In any system designed for electron cyclotron (EC) heating (ECH) and EC current drive in fusion plasmas, the launcher is the matching element between the plasma and the transmission line. Only an appropriate launcher achieves efficient use of the gyrotron power for the many different high-power EC H&CD applications. The frontier is now set at ≈4 MW of launched power at 110 to 140 GHz for ≈10 s, to be further moved to ≈10 MW, 1000 s in the near future. ITER will push the limit to 20 MW, 170 GHz. The workhorse of the antenna system is the front steering setup consisting of a movable mirror, or a mirror array, in front of the hot plasma, which provides for full flexibility in the EC H&CD applications. However, because of the concern associated with cooled and movable parts in a hostile environment, an arrangement with movable mirrors positioned far from the vessel port, and connected to the plasma by imaging waveguides, is being developed as a remote steering backup solution. In a reactor, where flexibility is much less relevant than reliability, the situation could reverse. Techniques for a radial scan of the deposition layer different from front beam steering are discussed in this paper. The ideal goal would be a 100% coupling of the launched EC power, to occur within ≈2% of the plasma size and through pipes of size negligible with respect to the vessel, without negative impact on plasma periphery in spite of the high power densities transmitted through the edge.

ANALYSIS OF TIMING PROPERTIES OF ELECTRICAL POWER SYSTEM PROTECTION

In electrical power systems, the coordination of protections in time domain is important and difficult problem. The time settings of protection relays have to be adapted to the time characteristics of electrical power system plants and the delay times of the other protections. In the paper, Fault Trees with Time Dependencies (FTTDs) are used in selection of values of the delay times of primary (local) and remote backup protections. In the FTTD, events and gates are characterized by time parameters. These time parameters are derived from the time characteristics of protection devices and the inherent delay times of protection equipment.

ISCSI analysis system and performance improvement of sequential access in a long‐latency environment

AbstractThe iSCSI protocol, approved by the IETF in February 2003, is used by data centers to offer storage outsourcing and remote backup services. A key issue when accessing remote storage over iSCSI is minimizing the performance degradation caused by network distance. Because iSCSI's performance is dictated by the iSCSI protocol, the SCSI protocol, the network, network devices, and so on, there is a need for a capable analysis system that comprehends all these layers. This paper discusses the functions of an iSCSI analysis system developed by the authors. With existing iSCSI equipment, if the system is not optimized for the conditions on the network, then increasing distance will cause a dramatic decrease in performance. With the proposed iSCSI analysis system, the authors have been able to elucidate the root causes of this performance degradation, and bring performance nearly to the level of the network substrate's limit. © 2005 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 89(4): 55–69, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20238

Enhanced management method of storage area network (SAN) server with random remote backups

A SAN (storage area network) is a mass storage solution, that is, designed to provide a high-reliability and high-speed network over fiber optic link. This paper is dealing with the stochastic SAN server management method which is focused on reliability. The (remote) backup servers are hooked up by the long-haul network and replace broken main severs immediately. If the SAN servers are represented as “machines”, this system can be solved by using the stochastic maintenance model with main unreliable and random auxiliary spare (remote backup) machines, subject to random breakdowns, repairs, and two replacement policies: one for busy and another for idle or vacation periods. When the repair facility is not available because of the given conditions, auxiliary machines are being used for backups. Unlike existing models, the availability of auxiliary machines is changed for each activation of the system. Analytically tractable results are obtained by using a duality principle (which enables us to treat a more rudimentary system), semiregenerative analysis, and multivariate marked renewal processes. The results are demonstrated in the framework of optimized SAN server allocation problems with unreliable backup servers.

An enhanced zone 3 algorithm of a distance relay using transient components and state diagram

Zone 3 of a distance relay is used to provide the remote backup protection in case of the failure of the primary protection. However, the risk of maloperation under stressed conditions such as heavy loading, voltage, and transient instability is quite high. Zone 3 is used in combination with the derivatives of the voltage and current, etc. to prevent maloperation. At times, the impedance characteristics that restrict the tripping area of relay are used to avoid maloperation due to load encroachment. This work presents a novel zone 3 scheme based on combining the steady-state components (i.e., 60 Hz) and the transient components (TCs) using a state diagram that visualizes the sequence of studies that emanate from the sequence of events. The simulation results show that the novel zone 3 distance relay elements using the proposed method operate correctly for the various events.

The basics of reliable distributed storage networks

Because of storage protocols that operate over extended distances, various distributed storage applications that improve the efficiency and reliability of data storage are now possible. Distributed storage applications improve efficiency by allowing any network server to transparently consolidate and access data stored in multiple physical locations. Remote backup and mirroring improve the system's reliability by copying critical data. These processes improve efficiency by eliminating backup downtime and manual backup operations. Business continuity and disaster recovery capabilities enable enterprises to recover quickly and transparently from system failure or data loss. Storage protocols and gateway devices enable rapid and transparent data transfer between mainframe applications and open-systems applications. NAS applications provide shared file access for clients using standard LAN-based technology, and can integrate with SAN architectures to provide truly distributed network capabilities. All these distributed storage network applications enable IT managers to improve data availability and reliability while minimizing management overhead and costs.

Sustained data recording system based on disk array

Most sustained data recording systems in many real-time fields are based on tape equipments. We have developed an innovative sustained data recording system based on disk array which consists of Array Controller Module (ACM), String Controller Module (SCM) and Main Controller Module (MCM). This system has a better performance and higher reliability than the traditional tape recorder and can be used conveniently in many areas of data recording, storing, playback, and remote backup. This novel recording system has been used in radar data recorder for spacecraft orbit tracking and satellite remote sensing data recording successfully.

Storage area networking - Performance study of iscsi-based storage subsystems

iISCSI is emerging as an end-to-end protocol for transporting storage I/O block data over IP networks. By exploiting the ubiquitous Internet infrastructure, iSCSI greatly facilitates remote storage, remote backup, and data mirroring. This article evaluates the performance of two typical iSCSI storage subsystems by measuring and analyzing block-level I/O access performance and file-level access performance. In the file-level performance study, we compare file access performance in an NAS scheme with that in an iSCSI-based SAN scheme. Our test results show that Gigabit Ethernet-based iSCSI can reach very high bandwidth, close to that of a direct FC disk access in block I/O access. However, when the iSCSI traverses through longer distance, throughput relies heavily on the available bandwidth between the initiator and the target. On the other hand, the file-level performance shows that iSCSI-based file access (SAN scheme) provides higher performance than using NFS protocol in Linux and SMB protocol in Windows (NAS scheme). However, the advantage of using iSCSI-based file accesses decreases as the file size increases. The obtained experimental results shed some light on the performance of applications based on iSCSI storage.

RORIB

Data plays an essential role in business today. Most, if not all, E-business applications are database driven, and data backup is a necessary element of managing data. Backup and recovery techniques have always been critical to any database, and as real-time databases are used more often, real-time online backup strategies become critical to optimize performance. In this paper, current backup methods are discussed and evaluated for response time and cost. A prototype device driver, RORIB (Real-time Online Remote Information Backup) is presented and discussed. An experiment is conducted comparing the performance, in terms of response time, of the prototype and several current backup strategies. RORIB provides an economic and efficient solution for real-time online remote backup. Significant improvement in response time is demonstrated using this prototype device driver when compared to other types of software-driven backup protocols. Another advantage of RORIB is that the cost is negligible when compared to other hardware solutions for backup, such as Storage Area Networks (SANs) and Private Backup Networks (PBNs). Additionally, this multi-layered device-driver uses TCP/IP (Telecommunications Protocol/Internet Protocol) which allows the driver to be a “drop in” filter between existing hardware layers and thus reduces the implementation overhead and improves portability. Linux is used as the operating system in this experiment because of its open source nature and its similarity to UNIX. This also increases the portability of this approach. The driver is transparent to both the user and the database management system. Other potential applications and future research directions for this technology are presented.