An intermittently used n-unit complex system

In this paper we study an n-unit warm standby system which is needed intermittently with need and no-need periods occurring alternately. The life time of a unit while online and duration of a no-need period are generally distributed random variables while all the others are exponentially distributed. Identifying certain regeneration points, we obtain an expression for the distribution function of the time to the first disappointment.     

Reliability and availability analysis of an n-unit outdoor power system subject to adjustable repair facility

This paper presents a newly developed stochastic mathematical model to represent a system of n active redundant outdoor power equipment. The system considered is subject to common cause failure and adjustable repair facility. Laplace transforms of the state probabilities, system reliability and availability equations are developed. In addition, steady-state availability and mean-time-between-failures expressions are developed. The special case when n = 2 is discussed numerically.     

An n-unit standby redundant system with r repair facilities and preventive maintenance

Identifying suitable regeneration points the availability and reliability of an n-unit warm standby system with r repair facilities, in which the operating online unit is subjected to preventive maintenance are obtained. A numerical example is provided to illustrate the results obtained. Based on the numerical result, an optimal PM policy is also derived.     

Cost analysis of an electronic repairable redundant system with critical human errors

In this paper, an electronic system consisting of two subsystems connected in series has been considered. One subsystem consists of two identical units connected in parallel while the other subsystem has only one unit. The system is to be in any of the three states: good, degraded and failed. The system suffers two types of failures, viz; unit failure and failure due to critical human error. The system can be repaired when it fails due to the failure of the units in the subsystems and cannot be repaired when it fails due to critical human errors. The repair for the system in any state follows general distribution. To make the system more applicable to practical life problems, time dependent probabilities have been evaluated so as to forecast the expected profit and the operational availability of the system at any time.     

Availability analysis of a repairable standby human-machine system

This paper presents a model representing a two units active and one unit on standby human-machine system with general failed system repair time distribution. In addition, the model takes into consideration the occurrence of common-cause failures. The method of linear ordinary differential equation is presented to obtain general expressions for system steady state availability for failed system repair time distributions such as Gamma, Weibull, lognormal, exponential, and Rayleigh. Generalized expressions for system reliability, time-dependent availability, mean time to failure, and system variance of time to failure are also presented. Selected plots are presented to demonstrate the impact of human error on system steady state availability, reliability, time-dependent availability, and mean time to failure.     

Availability measures for an intermittently used repairable system

This paper obtains generalized Availability Measures, as defined by L. A. Baxter, for an intermittently used repairable system. The regenerative point technique of Markov Renewal Processes has been employed to obtain these measures. Some comments have also been made on the discrepancies that existed in the derivation of availability in the past.     

Common-cause failure analysis of a k-out-of-n:G system with repairable units

A newly developed generalized expression for the mean time to failure of a k-out-of-n: G system composed of repairable units and subject to common-cause failures is presented. Also, reported are some special case system reliability and variance of time to failure formulas.     

Performance analysis of the adaptive EXP/PF channel scheduler in an AMC/TDM system

The adaptive EXP/PF AU; PL. DEFINE "EXP" ALSO channel scheduler proposed in Rhee et al. (2003) is an enhancement to the proportional fairness (PF) channel scheduler in that it guarantees delay sensitive services having the desired service delay outage probability as well as best-effort services in the forward link of an adaptive modulation and coding when used with time-division multiplexing (AMC/TDM) system. In this letter, assuming that there are many best-effort service users and one streaming service user requiring maximum delay constraints of 3 s, the system throughput of the adaptive EXP/PF scheduler is evaluated for different channel conditions of the streaming service user and is also compared with PF scheduler and its upper bound of throughput. The results show that the adaptive EXP/PF algorithm offers high system throughput as well as fairness among best-effort service users and guarantees streaming services of a desired delay constraint and outage probability.     

Cost-benefit analysis of one-server two-unit system with imperfect switch

This paper deals with the cost-benefit analysis of a one-server two-unit system subject to imperfect switch. The repair times of a unit and the switch are assumed to be arbitrarily distributed while the failure rate of a unit and of the switch are constants. Initially, one unit is switched on (switch is working at t = 0) and the other is kept as cold standby. The system breaks down when no unit is available or when the switch is not available although the unit is available for operation. The system is characterised by the probability of its being in the up or down state at an instant and integral equations have been set up for these probabilities by identifying the system at suitable regeneration epochs. These equations have been solved using Laplace Transform Technique. Explicit expressions for the expected durations the server is busy in (0, t) with the repair work of the unit and the switch have been obtained to carry out the analysis.     

Cost-benefit analysis of single server n-unit imperfect switch system with delayed repair

This paper deals with the cost-benefit analysis of a single-server n-unit system with an imperfect switch where failures of the items (units or the switch) are not detected unless either inspected by the server or when the system is down. Initially, one unit is put into operation (the switch is working at t = 0) and n − 1 units are kept as cold standbys. A failed unit is replaced by a standby if the switch and a standby are available. The server visits the system at random to check for the failed item and the check is instantaneous. When the system is down, either because of want of the standby or failure of the switch, the server is called for, and is assumed to arrive instantaneously. The revenue as well as the cost of repair are arbitrary functions of time. The expected net gain in (0, t) is evaluated assuming that all the life-time distributions are exponential and all the repair time distributions are arbitrary.     

模拟自适应干扰对消系统对消速度分析

现有自适应干扰对消系统理想对消速度模型不能描述系统稳定性问题。为此,引入系统稳定性条件修正对消速度模型。考虑了电调衰减器射频响应特性对对消速度的影响,进一步修正对消速度模型。结合仿真与实验对对消系统稳定性问题及电调衰减器射频响应特性进行测试,验证了修正模型的正确性。修正模型对后续样机的对消速度性能设计的参数分配具有参考意义。