A note on determining component reliability and redundancy

The computer program listed in a paper published in this journal was used to solve the two numerical examples in a substantial article published in 1977. Each of these two examples has five positive-integer variables and five continuous variables. The solutions presented here are better than the solutions in the 1977 article. Specifically, for the first example, the system reliability presented here is .9316741721437588 while the system reliability presented in the 1977 article is 0.91494. For the second example, the system reliability presented here is slightly better than that of the 1977 article: these are .9955247245296241 and 0.994767, respectively.The complete computer program for the first example and the computer outputs for the two examples are presented here. These computational results suggest that this computer program can be useful as a model to determine simultaneously both component reliability and redundancy.     

The effectiveness of adding standby redundancy at system andcomponent levels

The effect of adding standby redundancy at the system and component levels is studied. Compared with parallel redundancy, standby redundancy is both easier to implement and more essential in the study of maintenance policies. However, standby redundancy at the component level is not always better than that at the system level, whereas it is always better for parallel redundancy. It is shown that for a series (parallel) system, standby redundancy is more effective at the component (system) level. A simple proof is given     

Branch-and-bound redundancy optimization for a series system withmultiple-choice constraints

This paper considers a redundancy optimization problem in which multiple-choice and resource constraints are incorporated. The problem is expressed as a nonlinear integer programming problem and is characterized as an NP-hard problem. The purpose of the paper is to develop a SSRP (solution space reduction procedure). Therefore, the problem is analyzed first to characterize some solution properties. An iterative SSRP is then derived using those solution properties. Finally, the iterative SSRP is used to define an efficient B&BP (branch-and-bound procedure) algorithm. Experimental tests show how dramatically the SSRP can work on removing any intermediately-found unnecessary decision variables from further consideration in solution search, and how efficient this B&BP is     

LD redundancy system using polarization components for a submarine optical transmission system

An LD redundancy system having one cold standby laser diode is proposed to improve reliability in submarine optical transmission systems. This system makes use of the intrinsic laser polarization and consists of two LD modules and a polarization coupler connected by polarization maintaining (PANDA) fibers. The optical power insertion loss of this LD redundant system is 5.5 dB, including coupling loss between the laser diode and PANDA fiber. This LD redundant system will be applied in submarine optical repeaters.     

Reliability analysis and redundancy optimisation of a multimodular fault tolerant system

This paper presents the reliability analysis of a multimodular fault-tolerant system having N-modules in parallel. The reliability and MTSF of the system have been calculated and the expression for optimum number of modules has also been obtained with cost constraint in view.     

Investment analysis of introducing standby or redundancy into a production system

A systematic method is developed for investment decision on an additional equipment to form a standby or redundant system with a crucial equipment in a production system, considering the cost of repairs, switchover, operation, maintenance and production loss. A method is also proposed to compare these standby and redundant systems.     

Reliability evaluation of a first order standby system with module redundancy

By defining a module to be a coherent subsystem of independently operating components each with a constant failure rate, this article derives expressions for the reliability of a standby redundant system consisting of an operating module together with a cold or warm standby module. The closed form reliability expressions are dependent upon the minimal path sets of each module as well as the component failure rates. Expressions are also derived for the mean time to system failure as well as the variance of the system time to failure distribution.     

Reliability of a 2-Unit Standby Redundant System with Repair, Maintenance and Standby Failure

A repairable 2-unit warm-standby system with repair and preventive maintenance is discussed. Two models are presented. In each of the models the mean time to system failure and the steady state availability are calculated. Some numerical calculations illustrate the results.     

Operating system redundancy on an active,a stand-by or a passive basis

When applying redundancy, the system designer may find himself facing the dilemma of weighing the better life prospects of passive redundant hardware against the lower system complexity in the case of active redundant hardware. This dilemma is analyzed here by comparing the MTTF and the reliability obtained with active, stand-by and passive redundancy. The analysis makes use of Markov diagrams and a generalized reliability model that embraces all three types of redundancy and covers all types of failure which can occur in practice.     

The distributed control system — a world of new possibilities

Distributed control of machine automation is one of the main research areas of the Institute of Hydraulics and Automation at Tampere University of Technology in Finland. In this paper, the idea of distributed control is discussed. As a closely related subject, technological aspects of independent actuators and in-machine communication are presented. Transmission delays of in-machine communication are discussed as a possible application dependent source of problems. In the Conclusions, the further studies are also presented.     

Reliability evaluation of a phased mission system with time varying redundancy and failure probability

An attempt is made to derive the closed-form mathematical expression of a phased mission system reliability. A system is considered, where failure probability of a component and number of added redundancy change during the mission time. Several performance measures are also suggested.     

Trust chain generating and updating algorithm for dual redundancy system

In trusted computing field,the traditional construction mode of trust chain is only applicable to a single system.For the dual redundancy system,it causes break of transitive trust.A trust model suitable for dual redundancy system was proposed.Through double trust chain design and IMC/IMV interaction mechanism,the trust chain extension of trust from a computing unit to another unit was realized.On this basis,a trust chain generating and update algorithm for dual redundancy system was proposed.Finally,the validity of the proposed model was proved based on the trusting theory.     

A cyclic redundancy check‐based non‐coherent receiver for automatic identification system signals

A non‐coherent receiver for automatic identification system (AIS) signals is proposed in this paper. The proposed receiver is based on the Viterbi algorithm with cyclic redundancy check (CRC) trellis. It takes bit stuffing into consideration and is designed to simultaneously demodulate decode and correct the received messages. The complexity of the proposed receiver has been reduced with state‐complexity reduction. Simulations prove that the proposed receiver outperforms those AIS receivers without CRC trellis error correction in terms of BER and packet error rate. Copyright © 2015 John Wiley & Sons, Ltd.     

Polarization-maintaining optical fibers used for a laser diode redundancy system in a submarine optical repeater

Polarization-maintaining optical fibers are developed for installation in a submarine optical repeater. These fibers preserve the polarization of light emitted from laser diodes (LD's) to a single-mode fiber through a light-switching coupler. Crosstalk of less than -30 dB in a 1-m length of these optical fibers, called PANDA optical fibers, is achieved with a bending radius greater than 10 mm, twists of less than 60 turns, and tension of less than 3 kg, and ambient temperatures of-20-80degC. The mechanical strength of these fibers is the same as that of single-mode fibers.     

基于FPGA多路机载冗余图像处理系统的设计与实现

采用以FPGA作为核心处理器,实现了对多路DVISL频冗余信号的解码、编码、实时处理以及输出显示,并且信号通道增加冗余设计,因而加强了系统的稳定性和可靠性。电路设计简洁,具有较强的灵活性和扩展性。通过实际测试结果表明,系统能够流畅地对1600×1200分辨率,60Hz．gq新率,24位真彩色的高清视频进行实时处理,其系统可靠、稳定,实用性强。     

Optimal use of partial redundancy and the system reliability which results

Partial system triplication with a single majority vote is analysed to find (a) the region of superiority of partial triplication over total triplication and (b) over no redundancy, (c) the degree of partial triplication which maximises reliability, (d) the maximum system reliability produced by partial redundancy. Only approximate or numerical solutions to (a) and (c) have appeared previously. (b) and (d) are entirely new.     

Modelling and control of a high redundancy actuator

The high redundancy actuation concept is a completely new approach to fault tolerance, and it is important to appreciate that it provides a transformation of the characteristics of actuators so that the actuation performance (capability) degrades slowly rather than suddenly failing, even though individual elements themselves fail. This paper aims to demonstrate the viability of the concept by showing that a highly redundant actuator, comprising a relatively large number of actuation elements, can be controlled in such a way that faults in individual elements are inherently accommodated, although some degradation in overall performance will inevitably be found. The paper introduces the notion of fault-tolerant systems and the highly redundant actuator concept. Then a model for a two by two configuration with electro-mechanical actuation elements is derived. Two classical control approaches are then considered based on frequency domain techniques. Finally simulation results under a number of faults show the viability of the approach for fault accommodation without re-configuration.     

A new dynamic programming method for reliability & redundancy allocation in a parallel-series system

Reliability & redundancy allocation is one of the most frequently encountered problems in system design. This problem is subject to constraints related to the design, such as required structural, physical, and technical characteristics; and the components available in the market. This last constraint implies that system components, and their reliability, must belong to a finite set. For a parallel-series system, we show that the problem can be modeled as an integer linear program, and solved by a decomposition approach. The problem is decomposed into as many sub-problems as subsystems, one sub-problem for each subsystem. The sub-problem for a given subsystem consists of determining the number of components of each type in order to reach a given reliability target with a minimum cost. The global problem consists of determining the reliability target of subsystems. We show that the sub-problems are equivalent to one-dimensional knapsack problems which can be solved in pseudopolynomial time with a dynamic programming approach. We show that the global problem can also be solved by a dynamic programming technique. We also show that the obtained method YCC converges toward an optimal solution.     

Unreliability of a Standby System with Repair and Imperfect Switching

We evaluate and analyze a model of a 2-unit standby system with repair and imperfect switching. The model determines the cumulative probability that system failure occurs in a time interval 0 to T. In order to cope with arbitrary failure-time and repair-time distributions, a ``step by step' method is used which for practical purposes yields a sufficiently accurate result. The model results in explicit expressions which are very suitable for computer implementation. A simple illustrative example is given.