Hot Redundancy Research Articles

Decision support system for maintenance order priority of multistate coal handling system with hot redundancy

Decision support system for maintenance order priority of multistate coal handling system with hot redundancy

Future evolutions of EUSST collision avoidance service

Over the last few years, both the space debris population and the number of active satellites in orbit has dramatically increased. The risk of collision for satellite missions is a problem to an increasing extent targeted thoroughly by all agents involved in space situational awareness (SSA) & spacecraft operations. In the frame of the European Union Space Surveillance and Tracking (EU SST), the CA service is provided on a hot redundancy scheme involving the French and Spanish Operations Centres (FR-SSA Centre and S3TOC, respectively), to more than 50 organizations and 390 satellites at the time of writing.Given the dynamic space environment, EU SST CA service must evolve continuously to face the increase of the number of registered users and spacecraft, the diversity of users’ needs and the increasing number of close approaches.

Reliability analysis and redundancy optimization of k-out-of-n systems with random variable k using continuous time Markov chain and Monte Carlo simulation

This article discusses the problems associated with the redundancy of structures k-out-of-n as a method of increasing system availability. A parallel k-out-of-n system was considered, with k repairable and homogeneous components. The other (n – k) objects are in hot redundancy mode. Failures and repairs are independent processes, and each repaired object is treated as full-fledged in terms of operation. The system operates under dynamically changing conditions, so the minimum number of operable components essential for its proper operation is a random variable with a specific distribution. Component damages and repairs are independent stochastic processes. A probabilistic and simulation approach based on Continuous Time Markov Chain and Monte Carlo simulation is proposed. This study aims to optimize the number of components in the k-out-of-n structure, which will ensure the system operation with a certain availability and performance. The proposed methods were applied to real transport systems, for which models were developed with parameters estimated on the basis of empirical data. The convergence of the results obtained, using two methods, testifies to the correctness of the methodology used and the reliability of the models developed. The risk to system performance associated with changing input parameters was assessed using model sensitivity analysis. As indicated, the model is not susceptible to changes in the damage and repair intensity. It has also been shown that optimization of the k-out-of-n structure brings a significant reduction in the costs incurred for system development and operation.

SEU protection design for the prototype readout electronics of MAPS-based STCF inner tracker

The Super Tau Charm Facility (STCF) is a high-luminosity electron-positron collider experiment operating at center-of-mass energy of 2–7 GeV. Its primary goal is to explore flavor physics, CP-violations, and investigate physics beyond the Standard Model. The inner tracker (ITK) is a crucial component of the STCF tracking system, which is responsible for detecting particle hits, especially those with low momentum below 100 MeV/c. Its primary objectives include providing high detection efficiency and spatial resolution for charged particle tracks. However, the electronics of ITK is susceptible to single-event upset (SEU) caused by beam-related background. To address this, this paper presents a prototype of FPGA (Field Programmable Gate Array)-based electronics that can detect and automatically repair SEU induced soft errors in its Configuration Random Access Memory (CRAM) and whose Block Random Access Memory (BRAM) has been also subjected to commonly used hardening techniques. Importantly, the prototype's corrective operations do not result in any dead time due to hot redundancy backup. In the laboratory environment, we measured the bit error rate of the data transmission to be lower than 10-12 with a confidence level of 99.99%. Through neutron beam experiments conducted at China Spallation Neutron Source (CSNS) back-n white neutron source. We demonstrated that the readout electronics can effectively restore correct functionality and promptly rectify soft errors.

Link Redundancy Research and Reliability Analysis Based on Dual CAN Architecture

Aiming at the problem that special vehicles still need to ensure the reliability of vehicle-mounted bus communication in the long-term complex and strong interference communication environment, a link layer redundancy scheme based on dual CAN channels is proposed. By adding redundant modules and improving the redundancy mechanism, dual CAN controllers can not only realize the undisturbed switching of data communication in hot redundancy mode, but also realize the function of error correction and retransmission in cold redundancy mode. Finally, a mathematical model of the reliability of dual CAN redundancy is established through the Markov state transfer chain, and this model is compared with other models for analysis and evaluation to verify that its reliability is significantly improved.

Modeliranje sistema sa rezervom korišćenjem Petri mreža

Petri nets are very appropriate for modelling and analysis of different systems. In this paper, examples of repairable and irreparable systems modelled using Petri nets have been given. Systems with cold and hot redundancy have been analyzed, also. The redundancy is illustrated using the example of the electric power system.

Design and Reliability Analysis of a Tunnel-Detection AUV Based on a Heterogeneous Dual CPU Hot Redundancy System

A water conveyance tunnel is narrow and enclosed with a complex distribution of flow field. The performance of sensors such as Doppler log, magnetic compass, sonar, and depth gauge used by conventional underwater vehicles in the tunnel is greatly affected and can even fail. Aiming at the special operating environment and operational requirements of water conveyance tunnels, this paper designed an architecture suitable for pressurized water conveyance tunnel-detection autonomous underwater vehicles (AUVs). The tunnel-detection AUV (called AUV-T in this paper) with the architecture proposed in this paper could easily and smoothly complete inspection tasks in water conveyance tunnels, and field tests have verified the effectiveness of the architecture. Since an AUV in a water conveyance tunnel cannot go to the surface to rescue itself, in order to ensure its safety we designed the heterogeneous dual-CPU (Central Processing Unit) hot redundancy system based on dual communication lines. The reliability analysis showed that the system can significantly reduce the probability of AUV failure and ensure that the AUV can still be recovered even if it fails in the tunnel.

Redundancy and Derating Strategies for Modular Multilevel Converter for an Electric Drive

Reliability is an important issue in medium-voltage electrical drives. The modular multilevel converter (MMC) is an inherently fault-tolerant topology and an interesting solution when quadratic loads are used. Redundancy strategies can be used to extend system failure capability. The strategies presented in the literature affect the dynamic performance and the power losses of the MMC. In addition, for isolated and inaccessible areas, such as ore slurry pumps, which are widely used in mining industries, the maintenance time and cost are high. This paper compares four redundancy strategies applied in a MMC for an electric drive and presents a derating strategy to maintain the system operating after a greater number of failures. The results showed that hot redundancy schemes have less impact on the dynamic performance of the system than the strategy that operates with the nominal submodule number. Besides, hot redundancy presents up to 14.72% more power losses. For quadratic loads, such as the ore slurry pump, it was concluded that, for 14% of failures, the speed reference should be reduced to at least 28% in order to keep the system operating.

Behavioral study and availability optimization of a multi-state repairable system with hot redundancy

PurposeThe purpose of this paper is to identify the criticality of various sub-systems through the behavioral study of a multi-state repairable system with hot redundancy. The availability of the system is optimized to evaluate the optimum combinations of failure and repair rate parameters for various sub-systems.Design/methodology/approachThe behavioral study of the system is conducted through the stochastic model under probabilistic approach, i.e., Markov process. The first-order differential equations associated with the stochastic model are derived with the use of mnemonic rule assuming that the failure and repair rate parameters of all the sub-systems are constant and exponentially distributed. These differential equations are further solved recursively using the normalizing condition to obtain the long-run availability of the system. A particle swarm optimization (PSO) algorithm for evaluating the optimum availability of the system and supporting computational results are presented.FindingsThe maintenance priorities for various sub-systems can easily be set up, as it is clearly identified in the behavioral analysis that the sub-system (A) is the most critical component which highly influences the system availability as compared to other sub-systems. The PSO technique modifies input failure and repair rate parameters for each sub-system and evaluates the optimum availability of the system.Originality/valueA bottom case manufacturing system is under the evaluation, which is the main component of front shock absorber in two-wheelers. The input failure and repair rate parameters were parameterized from the information provided by the plant personnel. The finding of the paper provides the various availability measures and shows the grate congruence with the system behavior.

Efficient Performance Evaluation of Multi-Core SIMT Processors with Hot Redundancy

Redundancy is a well-known technique for improving yield and consequently reducing cost. Prior work has shown that at the architectural level, hot spare components not only increase yield (and reduce costs) when components are defective, but also improve performance. Hot spares, however, complicate system evaluation: the presence of defects affects what resources are available. Accurate performance evaluation thus requires the simulation of the entire population of resulting dice in order to determine the expected performance $E[P]$ of the system. While simply expensive for single system evaluation, it is intractable for design space exploration. We therefore introduce two $E[P]$ estimation techniques, $\hat{E}_{m}[P]$ and $\hat{E}_{s}[P]$ . $\hat{E}_{m}[P]$ evaluates the $m$ most likely configurations, and assumes the performance of all others is zero, reducing simulation by 93 percent. This remains computationally expensive for design space exploration when individual, detailed, simulations require hours. $\hat{E}_{s}[P]$ evaluates only the most likely configuration, and assumes its performance for all other configurations, reducing simulation by 98 percent, with no more than 2.6 percent error in $E[P]$ , sufficient for differentiating designs along the Pareto-optimal front during design space exploration. Consequently, designers may add redundancy, and evaluate system performance and cost, with no greater design effort than performance evaluation alone.

Autonomous frequency stabilization of two extended-cavity diode lasers at the potassium wavelength on a sounding rocket

We have developed, assembled, and flight-proven a stable, compact, and autonomous extended cavity diode laser (ECDL) system designed for atomic physics experiments in space. To that end, two micro-integrated ECDLs at 766.7 nm were frequency stabilized during a sounding rocket flight by means of frequency modulation spectroscopy (FMS) of 39^K and offset locking techniques based on the beat note of the two ECDLs. The frequency stabilization as well as additional hard- and software to test hot redundancy mechanisms were implemented as part of a state-machine, which controlled the experiment completely autonomously throughout the entire flight mission.

Taking into account type I and II errors of switching device for system with hot redundancy

One of the ways to improve the reliability of technical systems is the use of hot redundancy. Switching between the main and reserve elements makes switching device. When analyzing the reliability of such systems it is important to consider the impact of switching device on the reliability of the system. This influence is evident in the mistakes of the first and second kind that is the wrong switch or switching time of admission. Both errors reduce reliability of the system and lead to underutilization of resources. It is proposed a model of reliability of duplicated system with hot redundancy and imperfect switching device to determine the likelihood of its success. The peculiarity of the model is that it adequately takes into account type I and II errors for the switching device. Reliability of the system is described mathematically by the k-terminal dynamic fault tree, and the probability determined by the characteristics of homogeneous Markov model. It is quantitatively shown how increasing options that meet these errors, reduces the probability of failure of the system.

Development of the mechanical cryocooler system for the Sea Land Surface Temperature Radiometer

The Sea Land Surface Temperature Radiometer is a dual view Earth observing instrument developed as part of the European Global Monitoring for Environment and Security programme. It is scheduled for launch on two satellites, Sentinel 3A and 3B in 2014. The instrument detectors are cooled to below 85K by two split Stirling Cryocoolers running in hot redundancy. These coolers form part of a cryocooler system that includes a support structure and drive electronics. Aspects of the system design, including control and reduction of exported vibration are discussed; and results, including thermal performance and exported vibration from the Engineering Model Cryooler System test campaign are presented.

Performance optimisation of a multistate operating system with hot redundancy

This paper deals with the performance optimisation of a multistate operating system with hot redundancy using genetic algorithm (GA). A makeup water system, which is one of a unit of a thermal plant, has multistate system comprises of four subsystems working in series and parallel configuration. The failure and repair rates follow exponential distributions. The mathematical formulation is carried out using probabilistic approach and the Markov birth-death process is used to develop the Chapman-Kolmogorov difference differential equations. The expression for steady state availability has been derived after solving differential equations recursively. GA technique is used to compute optimum values of availability using various feasible failure/repair rates of each subsystem of makeup water system. The optimum availability value and steady state availability value obtained through Markov analysis is also compared in paper. So, the findings of the present paper will be highly useful to the plant management for enhancing system performance.

Modeling and analysis of a hybrid communication channel based on free-space optical and radio-frequency technologies

The mathematical model of a high-speed hybrid communication system based on free-space optical (FSO) and radio-frequency (RF) technologies is considered. Multimedia information is transmitted using two communication lines operating in the hot redundancy mode, namely, an FSO channel and a millimeter radio-frequency channel. In addition, we derive ergodicity conditions for the Markov process describing the system operation and provide some performance characteristics for the hybrid communication channel.