In this discussion, R-reliable intervals for the life-time of a parallel system, based on order statistics, are obtained. The failure distributions for the individual components are assumed to have densities of the form 1/θXif(xiθXi) where Xi, for i = 1, 2, …, n, are the failure times for the components in the parallel system and θXis are the scale parameters for the failure times Xi. A relationship between the confidence of the R-reliable interval for the total lifetime of the parallel system and the confidences of the R-reliable intervals for the lifetimes of the individual components is investigated. A bound for the confidence of the R-reliable interval for the total lifetime of the system is obtained. Examples for n=3 are presented. 相似文献
Dynamic routing and wavelength assignment problem in optical networks is a two-step problem that is influenced by the choice of a successful optimal path selection and wavelength assignment.
Proper selection techniques reduce the number of wavelengths required in the network and thereby improves traffic grooming. Heuristic algorithms and integer linear programming models help in selection of route and wavelength separately. Hence, the computation time is large which makes the system slow. A cost function is computed which uses independent parameters in the network for the selection of route and wavelength for a call. The heuristic reduces computation time by combining the search of route and wavelength to be assigned.
In addition, the network performance is analyzed with and without alternate routing along with proposed heuristics. The selection of proper route and wavelength finding technique is very essential since it improves the grooming factor of the network thereby allowing more traffic support by the network. Our objective is to investigate and propose a cost based heuristics for dynamic traffic routing and wavelength Assignment in WDM optical networks. For this we plan to develop cost functions and heuristics to compute the route and wavelength assignment strategy.
Here, our objective is to reduce the computation time for selection of route and wavelength assignment strategy by weighted cost function. The function has to include network parameters for its processing. Our work provides an overview about DRWA by applying cost based heuristics in WDM networks. This paper explains the proposed cost function and its applications in line with selection of independent parameters. The details of other functions like cost function formulation, hop-based route assignment, available wavelength based route assignment, mathematical analysis of proposed cost function are also explained. Results and discussions based on the findings are presented.
Wireless Personal Communications - Proper route selection between source and destination $$(s-d)$$ connection leads to efficient resource utilization which leads to the availability of resources... 相似文献
This research effort has developed a mathematical model for bathtub shaped hazards (failure rates) for operating systems with uncensored data. The model will be used to predict the reliability of systems with such hazards. Early in the life-time of a system, there may be a relatively large number of failures due to initial weaknesses or defects in materials and manufacturing processes. This period is called the “infant mortality” period. During the middle period of an operating system fewer failures occur and are caused when the environmental stresses exceed the design strength of the system. It is difficult to predict the environmental stress amplitudes or the system strengths as deterministic functions of time, thus the middle-life failures are often called “random failures.” As the system ages, it deterioates and more failures occur. This region of failure is called the “wearout” period. Graphing these failure rates simultaneously will result in a bathtub shaped curve. The model developed for this bathtub pattern of failure takes into account all three failure regions simultaneously. The model has been validated for accuracy by using Halley's mortality table and is used to predict the reliability with both least squares and maximum likelihood estimators. 相似文献
An approach to the study of inspection task design has been investigated. Twenty female inspectors did a simulated paced visual inspection task for 90 minutes each. The experimental variables were display size, product pacing, and fault information as a measure of defect probability. They were tested in a 15 point design with 3 replications of the center point. The criterion of performance was the fraction of total products correctly identified as being defect free. From the experimental data quantitative estimates of performance increments or decrements associated with changes in inspection task variables were determined. The implications of observations and their importance in the design of an inspection task have been discussed. 相似文献
The reliability of a series system with n independent components are estimated. The failure distributions of these components are assumed to be Weibull with parameters αi's and βi's. It is assumed that the shape parameters βi's are known. This reduces the reliability of the system to be a function of α = (α1, ..., αn), ξ(α), say. The MLE of ξ(α) is derived and an estimator which dominates the MLE in terms of risk, under squared error loss, is also derived. The predicted reliability using these two estimators are computed and compared. 相似文献
The authors consider the influence of the work environment on a system of nonrenewable components. The failure times for the components are Weibull distributed and the work environment has an inverse Gaussian distribution. A multivariate Weibull and inverse Gaussian mixture distribution is derived. Several pertinent properties for this multivariate distribution are discussed that shed some light on the nature of the distribution. The authors account for the operating environment and its changing nature by averaging over a parameter corresponding to the environment. The distribution is applied to find the mean number of components working at some mission time and the reliability for k-out-of-n components 相似文献
The reliability of a series system with independent components is estimated based on random samples from Weibull failure distributions with parameters &thetas;i and βi. It is assumed that the βi's are known, which reduces the reliability of the system to a function, γg(&thetas;), of &thetas;=(&thetas;1, . . ., &thetas;p). An estimate of γ(&thetas;) which is better than the MVUE of γ(&thetas;) in terms of mean square error is determined. The predicted reliability and the percentage improvement for this estimator is computed and compared with the usual MVUE of γ(&thetas;). The predicted reliability using the improved estimator is numerically closer to the true system reliability 相似文献