Redundancy Modes Research Articles

Failure mode division and remaining useful life prognostics of multi-indicator systems with multi-fault

Modern large-scale industrial systems are complex in structure, and their health states are usually reflected by multiple indicators. The performance degradation of multiple indicators surpasses respective threshold, causing multiple system faults, and multiple failure modes such as redundancy, fusion, and competition among different fault combinations exist, introducing new challenges when predicting remaining useful life (RUL) of the system. This study aims to establish a unified multi-failure mode division framework and the RUL prediction model under different failure modes for multi-indicator systems. Firstly, combination relationship between different fault types caused by multi-indicators outweighing their threshold is analyzed, and different redundancy, fusion, and competition failure modes are defined. Next, the formal fault type definition and its remaining time before occurrence under different failure modes are provided. The distribution calculation model of remaining time for different fault types is derived. The corresponding system's RUL prediction model under multi-fault competition is established, and degradation modeling, parameter estimation, and RUL distribution calculation are performed using the state-space model. Eventually, the validity of the RUL prediction model according to multiple failure modes is verified by numerical experiments. Taking XJTU-SY bearing and C-MAPSS datasets as two examples, the applicability and feasibility of the given method are proved.

Research on reliability evaluation method of DC circuit breaker based on Markov model

Natural commutation hybrid DC circuit breakers integrate the low loss of mechanical circuit breakers and the fast switching speed of solid-state circuit breakers. Its overall reliability determines the success or failure of the control of the current distribution of the DC distribution network. In this paper, the Fault Tree was used to analyze the basic components that caused the circuit breaker to fail, based on the topology of hybrid DC circuit breaker. The Markov model is introduced into the reliability modeling of hybrid DC circuit breaker to calculate steady state availability, failure rate and mean time between failures. On this basis, k/n(G) model and Gamma distribution are used to analyze the redundancy of weak components in hybrid DC circuit breakers. Finally, the influence of different redundancy components and different redundancy modes of weak components on the reliability of hybrid DC circuit breakers is analyzed quantitatively. The analysis methods and results can provide a reference for reliability prediction and design of hybrid DC circuit breakers.

Расчет надежности для системы с разнородным резервированием элементов в подсистемах

The purpose of the paper was to study the problem of confidence estimation of basic reliability indicators, such as the system failure-free operation probability for a given time and guaranteed uptime, with a given guarantee level, for a system model with arbitrary redundancy modes, loaded or unloaded, in various subsystems. When studying the problem, we relied on the elements test results. Problems like that are often found in engineering practice when designing and experimentally developing modern complex engineering systems and their various components. The paper gives the construction of lower confidence limits for the indicated main indicators of the system reliability based on the available statistical information on the test results of its elements, and also presents approximate asymptotic (for the case of high reliability) expressions obtained for the lower confidence limit of the system reliability function

Cryopreservation of Marchantia polymorpha spermatozoa.

The liverwort Marchantia polymorpha has become one of the model organisms, since it has less genetic redundancy, sexual and asexual modes of reproduction and a range of genomic and molecular genetic resources. Cryopreservation of fertile spermatozoa eliminates time, space and labor for growing and maintaining male plants in reproductive phase, and also provides an optional way to backup lines. Here we report a protocol to cryopreserve spermatozoa of M. polymorpha in liquid nitrogen. A cryoprotective solution containing sucrose, glycerol and egg yolk and controlled cooling and warming processes led to successful recovery of motile M. polymorpha spermatozoa after the cryogenic process. The survival rate and average motility of spermatozoa after cryopreservation were maintained at 71 and 54% of those before cryopreservation, respectively. Cryopreserved spermatozoa were capable of fertilization to form normal spores. The technique presented here confers more versatility to experiments using M. polymorpha and could be applied to preservation of plant spermatozoa in general.

RRect: A Novel Server-Centric Data Center Network with High Power Efficiency and Availability

In this paper, we propose a novel server-centric network for data centers, called RRect. Compared to existing server-centric networks, RRect provides a more graceful degradation performance in the presence of component failure. Meanwhile, RRect enjoys a linear diameter to the network order and multiple parallel paths. We present algorithms to find paths and to construct all parallel paths between any pair of servers in RRect. We also show that without using any power-aware routing algorithm, RRect behaves more power efficient in its interconnection network. To meet today's stringent high availability requirement, RRect can be configured into redundancy and failover scheme. In particular, RRect can be configured into both symmetric and asymmetric redundancy modes to cater different applications’ needs, which cannot be implemented in existing server-centric networks. Moreover, RRect gives more flexibility to adjust the network size. Given the same switches, by fine tuning the parameters, RRect provides numerous structures with different sizes, while preserving the properties of short diameter and multiple parallel paths. Our comprehensive simulations show that RRect gives much better graceful degradation performance in the presence of component failure, and RRect saves much energy in the interconnection network. Meanwhile, RRect can maintain the same performance on many critical metrics as BCube, including short diameter and excellent aggregate throughput. All these features make RRect a very empirical structure for enterprise dater center network products.

Sliding Mode Control Reconfiguration of Actuator Faults for a Large Civil Aircraft Using Fixed-point Iteration Control Allocation

Control reconfiguration of flight control system for a large civil aircraft is a difficult problem because of its control surface redundancy and different flight modes. To solve the problem of a jammed surface fault, a sliding mode reconfigurable controller is proposed. Firstly the dynamics model and faults model of the aircraft are established. Secondly, a sliding mode reconfigurable controller is designed to stabilize the flight control system. Finally, to improve reconfiguration performance, a Sliding Mode Controller with fixed-point iteration Control Allocation scheme (SMCCA) is proposed to achieve better tracking performance and optimal control surface distribution under the fault circumstance. Simulation results of the Boeing747 model with elevator faults show that the SMCCA algorithm has better performances in robust stability and command tracking than those in LQR and SMC.

다중화 구조 제어시스템에 대한 신뢰도 분석

Since a slight malfunction of control systems in a nuclear power plant may cause huge catastrophes, such control systems usually have multiple redundancy and reliable features, and their reliability and availability should be analyzed and verified thoroughly. This paper performed the reliability analysis of the SPLC (Safety Programmable Logic Controller) that is under developed as the control systems for the next generation nuclear power plant. One of the key features of SPLC is that it has multiple redundancy modes as faults happen, which means the reliability analysis for one fixed redundant model is not enough to analyze the reliability of SPLC. With considering this reconfigurable concept, FTA (Fault Tree Analysis) was used to capture fault-relationship among sub-modules. The analysis results show that MTTF (Mean Time to Fault) of SPLC is 45,080 hours, which is a about 4.5 times longer than the regulation, 10,000 hours.

Adaptive fault‐tolerant control based on hybrid redundancy

ABSTRACTThis paper presents a new actuator fault accommodation based on a hybrid of static and dynamic redundancies. Introduction of the activation functions for the actuators makes it possible to switch the redundancy modes appropriately. These functions are switched among the two values, 0 and 1, by monitoring only the input and output signals, and they determine the power supplies for the actuators. Furthermore, in this paper, the adaptively switching high‐gain feedback controller is developed to achieve the λ‐tracking in the presence of unknown perturbations. The adaptive tracker is modified to suit the switching mechanism for tuning the activation‐functions. Thus, the proposed adaptive fault‐tolerant control system with a hybrid redundancy has the advantages of both static and dynamic redundancies, and has high robustness with regard to actuator failures and variations in dynamics. In addition, a practical application to a chemical reactor is shown to confirm the effectiveness of the overall adaptive fault‐tolerant control system. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.

The “primary integrity parameters” — Design parameters for safety systems

This paper discusses the Primary Integrity Parameters (PIPs) - design attributes that, as a group, determine the level of safety integrity achieved by a Programmable Electronic System (PES). These parameters include redundancy level, failure rates and modes, diagnostic coverage factor, common cause failure rates, on-line manual test interval/duration, maintainability and security. The paper demonstrates that the level of safety provided by a PES is not simply a factor of any one of these attributes, but is determined by the total combination of the PIPs. Examples are given to show the dependency of the system safety on each of the parameters.

Solution and mechanical mixing of metal powder and polymeric binder compared: J.W. O'Connor et al, (Rensselaer Polytechnic Inst, Troy, New York, USA)

Customers of high-technology industrial process control instrumentation systems are demanding that these systems provide enhanced functionality, features, and flexibility. Examples are: an integrated system with a distributed architecture, user-friendly configuration and reconfiguration control and monitoring from an operator's console, supervisory and optimizing contiol through the use of Computer Interfacing, trend and other historical recording, built-in diagnostics and error message handling, and other Management Information Systems capabilities.Customers are also demanding that these systems give improved performance, including reliability, maintainability, and availability (RMA). To ensure that these RMA performance characteristics are met during the design, development, manufacture, and deployment (use) of the equipment requires Reliability, Quality Control, and Quality Assurance Programs be put in place. The Design and Development Program must include redundancy and back-up operating modes for any critical functions, methods of operating around any single, critical hardware failure (this may include software methods) and, in cases of critical control loops, the back-up operating modes also need to include continuous automatic control even for the unusual case of the operator losing all communication to the control process instrumentation. This also would need to allow repair by replacement of the local primary Controllers while operating online in a back-up mode. These capabilities plus built-in diagnostics will improve maintainability, reduce downtimes, and thereby improve availability.Improving reliability will then reduce required maintenance actions, which will also improve availability. The entire Reliability Program is aimed at assuring and improving reliability. The Reliability Program includes the following major parts:Component QualificationsIC Screening to the Equivalent of MIL-STD-883 Quality Level B-2Component Design Derating RequirementsDesign Reviews, including Stress and Application AnalysesHardware and Software Reliability Growth TestingThe Reliability Growth Testing consists of:Board Level TestingSubsystem TestingSoftware Integration TestingSystem Functional and Hardware TestingThis paper describes the Reliability Growth Testing that has taken place for the Taylor™ MOD 300™ System product line, the advantages that are being experienced from that testing for that 3rd-generation microprocessor-based control instrumentation equipment, and also some of the improvement results. In the manufacturing area the expected results of getting further Reliability Growth (reducing infant mortality failures from getting into the field) by applying an all-equipment Environmental Stress Screening (consisting of a powered and monitored temperature cycling test) is also described.

Cost effective production of metal injection moulded parts: R.C. Drewes, (Advanced Forming Technologies Inc, Longmont, Colorado, USA)

Customers of high-technology industrial process control instrumentation systems are demanding that these systems provide enhanced functionality, features, and flexibility. Examples are: an integrated system with a distributed architecture, user-friendly configuration and reconfiguration control and monitoring from an operator's console, supervisory and optimizing contiol through the use of Computer Interfacing, trend and other historical recording, built-in diagnostics and error message handling, and other Management Information Systems capabilities.Customers are also demanding that these systems give improved performance, including reliability, maintainability, and availability (RMA). To ensure that these RMA performance characteristics are met during the design, development, manufacture, and deployment (use) of the equipment requires Reliability, Quality Control, and Quality Assurance Programs be put in place. The Design and Development Program must include redundancy and back-up operating modes for any critical functions, methods of operating around any single, critical hardware failure (this may include software methods) and, in cases of critical control loops, the back-up operating modes also need to include continuous automatic control even for the unusual case of the operator losing all communication to the control process instrumentation. This also would need to allow repair by replacement of the local primary Controllers while operating online in a back-up mode. These capabilities plus built-in diagnostics will improve maintainability, reduce downtimes, and thereby improve availability.Improving reliability will then reduce required maintenance actions, which will also improve availability. The entire Reliability Program is aimed at assuring and improving reliability. The Reliability Program includes the following major parts:Component QualificationsIC Screening to the Equivalent of MIL-STD-883 Quality Level B-2Component Design Derating RequirementsDesign Reviews, including Stress and Application AnalysesHardware and Software Reliability Growth TestingThe Reliability Growth Testing consists of:Board Level TestingSubsystem TestingSoftware Integration TestingSystem Functional and Hardware TestingThis paper describes the Reliability Growth Testing that has taken place for the Taylor™ MOD 300™ System product line, the advantages that are being experienced from that testing for that 3rd-generation microprocessor-based control instrumentation equipment, and also some of the improvement results. In the manufacturing area the expected results of getting further Reliability Growth (reducing infant mortality failures from getting into the field) by applying an all-equipment Environmental Stress Screening (consisting of a powered and monitored temperature cycling test) is also described.

Topography measurement of porous surfaces: P. Kjelsteen, (Danfoss AS, Nordborg, Denmark)

Customers of high-technology industrial process control instrumentation systems are demanding that these systems provide enhanced functionality, features, and flexibility. Examples are: an integrated system with a distributed architecture, user-friendly configuration and reconfiguration control and monitoring from an operator's console, supervisory and optimizing contiol through the use of Computer Interfacing, trend and other historical recording, built-in diagnostics and error message handling, and other Management Information Systems capabilities.Customers are also demanding that these systems give improved performance, including reliability, maintainability, and availability (RMA). To ensure that these RMA performance characteristics are met during the design, development, manufacture, and deployment (use) of the equipment requires Reliability, Quality Control, and Quality Assurance Programs be put in place. The Design and Development Program must include redundancy and back-up operating modes for any critical functions, methods of operating around any single, critical hardware failure (this may include software methods) and, in cases of critical control loops, the back-up operating modes also need to include continuous automatic control even for the unusual case of the operator losing all communication to the control process instrumentation. This also would need to allow repair by replacement of the local primary Controllers while operating online in a back-up mode. These capabilities plus built-in diagnostics will improve maintainability, reduce downtimes, and thereby improve availability.Improving reliability will then reduce required maintenance actions, which will also improve availability. The entire Reliability Program is aimed at assuring and improving reliability. The Reliability Program includes the following major parts:Component QualificationsIC Screening to the Equivalent of MIL-STD-883 Quality Level B-2Component Design Derating RequirementsDesign Reviews, including Stress and Application AnalysesHardware and Software Reliability Growth TestingThe Reliability Growth Testing consists of:Board Level TestingSubsystem TestingSoftware Integration TestingSystem Functional and Hardware TestingThis paper describes the Reliability Growth Testing that has taken place for the Taylor™ MOD 300™ System product line, the advantages that are being experienced from that testing for that 3rd-generation microprocessor-based control instrumentation equipment, and also some of the improvement results. In the manufacturing area the expected results of getting further Reliability Growth (reducing infant mortality failures from getting into the field) by applying an all-equipment Environmental Stress Screening (consisting of a powered and monitored temperature cycling test) is also described.

Adaptable Large-Scale-Integrated Military and Space Systems

The advent of low-cost microelectronics and of large-scale integration (LSI) in particular has made it practical to design adaptable circuits and systems to achieve various significant objectives. The two objectives discussed in this paper are the design and technology of Microelectronic Multifunction Circuit Blocks to specifically simplify the logistics support problem of large, long-life military systems and the use of Dynamically Redundant Microelectronic Circuit Blocks to mechanize efficient self-repair systems. Presently practical adaptation techniques involve reversible and irresversible electronic modification of the interconnection pattern which is super-imposed on a matrix of components or of logic or analog circuits. Future possibilities include changes in the component characteristics themselves. Among the various design and technological approaches to adaptable multifunction microcircuits the Pin-Programmable Adaptable Microcircuits are recognized as the most versatile. This adaptation scheme is then extended to include dynamically redundant microcircuits. The basic principle of dynamic redundancy is that the interconnection paths between the redundant circuit blocks are not fixed but can be varied by external control signals. This adaptation is accomplished by switches placed around distribution points in the interconnection pattern. The switches are opened and closed by a logic control network programmed by an Equipment Redundacny Programme. Each circuit can operate in various Redundancy Modes depending on the state of the switches around it. The basic terms are defined and the advantages of dynamic redundancy are listed.

Cyclic product codes and their implementation

In many communication systems, variable-redundancy coding schemes are highly desirable either due to the fact that messages of various degrees of importance are present, or due to some change in the real communication channel. A class of “cyclic product codes” presented in this paper is capable of operating in variable redundancy modes. In the simplest case, the generator polynomial in the high redundancy mode is g(x) = g 1 (x)g 2 (x) , while the generator polynomial in the low redundancy mode is only g 1 (x) . It is shown that efficient product codes can be constructed offering different degrees of protection against independent errors, burst errors, and multiple burst errors. It is also shown that particularly simple implementation for cyclic product codes is possible. In fact, the complexity of the entire decoder can be made roughly the same as that of the decoder for the high redundancy code alone. Hence, the implementation of low-redundancy codes is accomplished with little extra cost.