Aging properties of the lifetime in simple additive degradation models

2011 ◽  
Vol 24 (4) ◽  
pp. 753-760 ◽  
Author(s):  
Xiaohu Li ◽  
Rongfang Yan ◽  
Yiqiang Zhao
Symmetry ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1532
Author(s):  
Abdulhakim A. Albabtain ◽  
Mansour Shrahili ◽  
Lolwa Alshagrawi ◽  
Mohamed Kayid

A novel methodology for modelling time to failure of systems under a degradation process is proposed. Considering the method degradation may have influenced the failure of the system under the setup of the model several implied lifetime distributions are outlined. Hazard rate and mean residual lifetime of the model are obtained and a numerical situation is delineated to calculate their amounts. The problem of modelling the amount of degradation at the failure time is also considered. Two monotonic aging properties of the model is secured and a characterization property of the symmetric degradation models is established.


Author(s):  
Mohamed Kayid ◽  
Lolwa Alshagrawi

Although the ordinary time-to-failure degradation-based model has been extensively used in practice, it also has its limitations. In this paper, we consider a time-to-failure degradation-based model recently proposed by Albabtain et al., where a limiting conditional survival probability entertains further stochastic relationships between the failure time and the degree of degradation. In the particular case where the limited survival probability is available for the proportional failure rate model, the model is developed using two well-known degradation paths, namely the additive degradation path and the multiplicative degradation path, each of which has a component of random variation. Preservation of various stochastic orders and aging properties of the random variation component in the model in the described setting is developed. To illustrate the model in the modified design, some examples of interest in reliability are presented.


CIM Journal ◽  
2016 ◽  
Vol 7 (2) ◽  
pp. 87-92 ◽  
Author(s):  
J. M. Reyes-Montes ◽  
B. L. Sainsbury ◽  
J. R. Andrews ◽  
R. P. Young

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 614
Author(s):  
Martyna Zagórska-Dziok ◽  
Aleksandra Ziemlewska ◽  
Tomasz Bujak ◽  
Zofia Nizioł-Łukaszewska ◽  
Zofia Hordyjewicz-Baran

Due to the constantly growing interest in ingredients of natural origin, this study attempts to evaluate the possibility of using extracts from three Ayurvedic plants in preparations for the care and treatment of skin diseases. Therefore, studies of antioxidant properties were carried out using DPPH and ABTS radicals, obtaining 76% and 88% of these radical scavenging, respectively. A significant decrease in the intracellular level of free radicals and an increase in the activity of the antioxidant enzyme-superoxide dismutase by almost 60% were also observed. In addition, the extracts were assessed for anti-inflammatory and anti-aging properties, obtaining over 70% inhibition of lipoxygenase activity and almost 40% of collagenase. Additionally, the cytoprotective properties of the obtained extracts on skin cells, keratinocytes and fibroblasts, were demonstrated. To assess the content of biologically active compounds, HPLC-electrospray ionization (ESI)-MS/MS multiple reaction monitoring (MRM) analyses were performed. The obtained results show that all three analyzed plants are a valuable source of biologically active substances with desired properties in the context of skin cell protection. Particularly noteworthy is the extract of Epilobium angustifolium L., for which the most promising results were obtained.


SPE Polymers ◽  
2021 ◽  
Author(s):  
Udomlak Sukatta ◽  
Prapassorn Rugthaworn ◽  
Wichudaporn Seangyen ◽  
Rattana Tantaterdtam ◽  
Wirasak Smitthipong ◽  
...  

2005 ◽  
Vol 24 (4) ◽  
pp. 197-208 ◽  
Author(s):  
Yuan-Jun Liu ◽  
Wen Zhai ◽  
Chuan-Lan He ◽  
Jian-Guo Deng ◽  
Ke-Jian Ji ◽  
...  

The aging rules of rigid polyurethane foam (PUR) at indoor storage and different hygrothermal conditions have been studied. Four parameters, which are mass, dimension, compressive strength and compressive modulus were tested. At indoor storage, mass, dimension and compressive strength vary slowly with an increase in aging time, while compressive modulus decreases quickly. PUR is sensitive to relative humidity (RH) verified by accelerated hygrothermal aging, and hydrolysis of ester group is the main reason resulting in the decrease of compressive properties. The filling with fire retardant and glass beads had some effect on hygrothermal aging properties of PUR. The addition of fire retardant increased compressive strength with aging time in the total trend, but it made dimension stability worse. The addition of glass beads slightly improved hygrothermal aging properties.


2015 ◽  
Vol 49 (4) ◽  
pp. 1235-1244 ◽  
Author(s):  
Song Xu ◽  
Jianying Yu ◽  
Canlin Zhang ◽  
Tingting Yao ◽  
Yubin Sun

2001 ◽  
Vol T92 (1) ◽  
pp. 253-255 ◽  
Author(s):  
Zou ◽  
Zou ◽  
R. Hutton ◽  
R. Hutton ◽  
S. Huldt ◽  
...  

1959 ◽  
Vol 32 (3) ◽  
pp. 739-747 ◽  
Author(s):  
J. R. Dunn ◽  
J. Scanlan

Abstract The thermal and photochemical aging of extracted dicumyl peroxide-, TMTD (sulfurless)- and santocure-vulcanized rubber, in presence of a number of metal and alkylammonium dithiocarbamates, has been investigated by measurements of stress relaxation. The dithiocarbamates have a considerable protective action upon the degradation of peroxide- and TMTD-vulcanizates, but they accelerate stress decay in santocure-accelerated vulcanizates. The reasons for this behavior are discussed. It is suggested that the excellent aging properties of unextracted TMTD vulcanizates are due to the presence of zinc dimethyldithiocarbamate formed during vulcanization.


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