Accelerated life testing(ALT)has been widely used to obtain information about the product's life characteristics at normal conditions in a relatively short period of time.Two key issues with ALT are test design an...Accelerated life testing(ALT)has been widely used to obtain information about the product's life characteristics at normal conditions in a relatively short period of time.Two key issues with ALT are test design and data analysis.The test design of constant stress ALT was studied in this paper.The test design usually combines engineering experiences with optimization models.Such approaches are hard to be implemented by practitioners.A"pure"empirical approach was presented to address this issue.With the proposed approach,some of the decision variables are determined based on the results from the literature,some of the other variables are determined based on engineering analysis and /or judgment,and the remaining variables are determined based on the empirical relations developed in this paper.A real-world example is included to illustrate the appropriateness of the proposed approach.展开更多
Objective: To examine immobilization stress-induced antioxidant defense alterations in rat kidney and the antioxidant effects of aqueous garlic extract in pre and post stress extract treatments. Methods: Albino rats w...Objective: To examine immobilization stress-induced antioxidant defense alterations in rat kidney and the antioxidant effects of aqueous garlic extract in pre and post stress extract treatments. Methods: Albino rats were treated with aqueous extract of garlic both before and 6 h of immobilization stress. Pro-oxidant eminence of rat kidney was assessed by determining the levels of glutathione, thiobarbituric acid reactive substances, aspartate aminotransferase, alanine aminotransferase, glucose, uric acid, alkaline phosphatase and antioxidant enzymes activities. Results: In response to 6 h of immobilization stress, a significant rise in the level of kidney enzymes was recorded. However, antioxidant enzyme activities showed a sharp decline. Conclusions: The extract treatment before and after the stress reverted the activities of above mentioned enzymes towards their control values. Hence, garlic extract can be given as nutritional supplement for scavenging the free radicals generated in rat kidney.展开更多
This paper proposes a simple constant-stress accel- erated life test （ALT） model from Burr type XII distribution when the data are Type-I progressively hybrid censored. The maximum likelihood estimation （MLE） of t...This paper proposes a simple constant-stress accel- erated life test （ALT） model from Burr type XII distribution when the data are Type-I progressively hybrid censored. The maximum likelihood estimation （MLE） of the parameters is obtained through the numerical method for solving the likelihood equations. Approxi- mate confidence interval （CI）, based on normal approximation to the asymptotic distribution of MLE and percentile bootstrap Cl is derived. Finally, a numerical example is introduced and then a Monte Carlo simulation study is carried out to illustrate the pro- posed method.展开更多
基金National Natural Science Foundation of China(No.71371035)
文摘Accelerated life testing(ALT)has been widely used to obtain information about the product's life characteristics at normal conditions in a relatively short period of time.Two key issues with ALT are test design and data analysis.The test design of constant stress ALT was studied in this paper.The test design usually combines engineering experiences with optimization models.Such approaches are hard to be implemented by practitioners.A"pure"empirical approach was presented to address this issue.With the proposed approach,some of the decision variables are determined based on the results from the literature,some of the other variables are determined based on engineering analysis and /or judgment,and the remaining variables are determined based on the empirical relations developed in this paper.A real-world example is included to illustrate the appropriateness of the proposed approach.
基金Supported by King Abdulaziz City for Science and Technology(KACST)project number 13-MED293-3
文摘Objective: To examine immobilization stress-induced antioxidant defense alterations in rat kidney and the antioxidant effects of aqueous garlic extract in pre and post stress extract treatments. Methods: Albino rats were treated with aqueous extract of garlic both before and 6 h of immobilization stress. Pro-oxidant eminence of rat kidney was assessed by determining the levels of glutathione, thiobarbituric acid reactive substances, aspartate aminotransferase, alanine aminotransferase, glucose, uric acid, alkaline phosphatase and antioxidant enzymes activities. Results: In response to 6 h of immobilization stress, a significant rise in the level of kidney enzymes was recorded. However, antioxidant enzyme activities showed a sharp decline. Conclusions: The extract treatment before and after the stress reverted the activities of above mentioned enzymes towards their control values. Hence, garlic extract can be given as nutritional supplement for scavenging the free radicals generated in rat kidney.
基金supported by the National Natural Science Foundation of China(7117116470471057)
文摘This paper proposes a simple constant-stress accel- erated life test （ALT） model from Burr type XII distribution when the data are Type-I progressively hybrid censored. The maximum likelihood estimation （MLE） of the parameters is obtained through the numerical method for solving the likelihood equations. Approxi- mate confidence interval （CI）, based on normal approximation to the asymptotic distribution of MLE and percentile bootstrap Cl is derived. Finally, a numerical example is introduced and then a Monte Carlo simulation study is carried out to illustrate the pro- posed method.
