Orderings of component level versus system level at active redundancies for coherent systems with dependent components

2021 ◽  
pp. 1-23
Author(s):  
Rongfang Yan ◽  
Junrui Wang ◽  
Bin Lu
Keyword(s):  
Hazard Rate ◽  
System Level ◽  
Stochastic Comparison ◽  
Coherent Systems ◽  
Component Level ◽  
Comparison Results ◽  
Versus System ◽  
Level Versus ◽  
Theoretical Results ◽  
Complete Matching

This paper investigates the issue of stochastic comparison of multi-active redundancies at the component level versus the system level. Based on the assumption that all components are statistically dependent, in the case of complete matching and nonmatching spares, we present some interesting comparison results in the sense of the hazard rate, reversed hazard rate and likelihood ratio orders, respectively. And we also obtain two comparison results between relative agings of resulting systems at the component level and the system level. Several numerical examples are provided to illustrate the theoretical results.

On allocation of spares at component level versus system level

1997 ◽  
Vol 34 (01) ◽  
pp. 283-287 ◽  
Author(s):  
Harshinder Singh ◽  
R. S. Singh
Keyword(s):  
Survival Analysis ◽  
Hazard Rate ◽  
System Level ◽  
Component Level ◽  
Design Engineers ◽  
Versus System ◽  
Level Versus ◽  
Life Distributions ◽  
Likelihood Ratio Ordering ◽  
Hazard Rate Ordering

Design engineers are well aware that a system where active spare allocation is made at the component level has a lifetime stochastically larger than the corresponding system where active spare allocation is made at the system level. In view of the importance of hazard rate ordering in reliability and survival analysis, Boland and El-Neweihi (1995) recently investigated this principle in hazard rate ordering and demonstrated that it does not hold in general. They showed that for a 2-out-of-n system with independent and identical components and spares, active spare allocation at the component level is superior to active spare allocation at the system level. They conjectured that such a principle holds in general for a k-out-of-n system when components and spares are independent and identical. We prove that for a k-out-of-n system where components and spares have independent and identical life distributions active spare allocation at the component level is superior to active spare allocation at the system level in likelihood ratio ordering. This is stronger than hazard rate ordering, thus establishing the conjecture of Boland and El-Neweihi (1995).

On allocation of spares at component level versus system level

1997 ◽  
Vol 34 (1) ◽  
pp. 283-287 ◽  
Author(s):  
Harshinder Singh ◽  
R. S. Singh
Keyword(s):  
Survival Analysis ◽  
Hazard Rate ◽  
System Level ◽  
Component Level ◽  
Design Engineers ◽  
Versus System ◽  
Level Versus ◽  
Life Distributions ◽  
Likelihood Ratio Ordering ◽  
Hazard Rate Ordering

Design engineers are well aware that a system where active spare allocation is made at the component level has a lifetime stochastically larger than the corresponding system where active spare allocation is made at the system level. In view of the importance of hazard rate ordering in reliability and survival analysis, Boland and El-Neweihi (1995) recently investigated this principle in hazard rate ordering and demonstrated that it does not hold in general. They showed that for a 2-out-of-n system with independent and identical components and spares, active spare allocation at the component level is superior to active spare allocation at the system level. They conjectured that such a principle holds in general for a k-out-of-n system when components and spares are independent and identical. We prove that for a k-out-of-n system where components and spares have independent and identical life distributions active spare allocation at the component level is superior to active spare allocation at the system level in likelihood ratio ordering. This is stronger than hazard rate ordering, thus establishing the conjecture of Boland and El-Neweihi (1995).

Farmers' role in sustainable agriculture research

1990 ◽  
Vol 5 (4) ◽  
pp. 178-182 ◽  
Author(s):  
William Lockeretz ◽  
Molly D. Anderson
Keyword(s):  
Sustainable Agriculture ◽  
Agricultural Research ◽  
Dominant Role ◽  
Full Range ◽  
System Level ◽  
Component Level ◽  
Versus System ◽  
Level Versus ◽  
Publicly Supported

AbstractInvolvement of farmers in sustainable agricultural research can have important benefits, since farmers originated many sustainable agriculture innovations and can contribute a valuable perspective different from that of researchers. However, this does not mean, as is sometimes said, that all kinds of sustainable agricultural research necessarily should give farmers a major role—perhaps the dominant role—in choosing topics and overseeing the work. This belief overlooks the fact that farmers are just one of many groups that publicly supported research is supposed to serve and that their interests do not by themselves embody the full range of goals that sustainable agriculture tries to achieve. Moreover, although farmers can bring valuable insights to research, these alone will not be enough to insure that a sustainable agriculture research program has an appropriate mix of applied versus basic, short-term versus long-term, and component-level versus system-level studies.

On inactivity times of failed components of coherent system under double monitoring

2021 ◽  
pp. 1-18
Author(s):  
Zhouxia Guo ◽  
Jiandong Zhang ◽  
Rongfang Yan
Keyword(s):  
Sufficient Conditions ◽  
Reliability Function ◽  
Coherent System ◽  
Stochastic Comparison ◽  
Coherent Systems ◽  
Stochastic Behavior ◽  
Numerical Examples ◽  
Comparison Results ◽  
Aging Properties ◽  
Theoretical Results

Abstract This article discusses the stochastic behavior and reliability properties for the inactivity times of failed components in coherent systems under double monitoring. A mixture representation of reliability function is obtained for the inactivity times of failed components, and some stochastic comparison results are also established. Furthermore, some sufficient conditions are developed in terms of the aging properties of the inactivity times of failed components. Finally, some numerical examples are presented to illustrate the theoretical results.

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