Integrated optimization of maintenance interventions and spare part selection for a partially observable multi-component system

Advanced technical systems are typically composed of multiple critical components whose failure cause a system failure. Often, it is not technically or economically possible to install sensors dedicated to each component, which means that the exact condition of each component cannot be monitored, but a system level failure or defect can be observed. The service provider then needs to implement a condition based maintenance policy that is based on partial information on the systems condition. Furthermore, when the service provider decides to service the system, (s)he also needs to decide which spare part(s) to bring along in order to avoid emergency shipments and part returns. We model this problem as an infinite horizon partially observable Markov decision process. In a set of numerical experiments, we first compare the optimal policy with preventive and corrective maintenance policies: The optimal policy leads on average to a 28% and 15% cost decrease, respectively. Second, we investigate the value of having full information, i.e., sensors dedicated to each component: This leads on average to a 13% cost decrease compared to the case with partial information. Interestingly, having full information is more valuable for cheaper, less reliable components than for more expensive, more reliable components

The Effect of Caffeic Acid Phenethyl Ester (CAPE) Fortification on the Liver Element Distribution that Occurs After Exercise

PubMed ID: 26743862The purpose of this study is to examine the effect of the caffeic acid phenethyl ester (CAPE) fortification applied to the rats, which were made to exercise, on the liver elements. The study was conducted on 32 Sprague-Dawley male rats. The experimental animals were divided into 4 groups in equal numbers. Group 1 is the group which was applied 10 ?mol/kg/day CAPE as intraperitoneal (IP) for 4 weeks, and they were not made to exercise at the end of the application. Group 2 is the group which was applied 10 ?mol/kg/day CAPE as IP for 4 weeks, and they were made to exercise at the end of the 4th week. Group 3 is the general control group. Group 4 is the swimming control group. A 10 mmol/kg CAPE application dissolved in ethyl alcohol of 10 % was applied to the CAPE group. Sodium (Na), zinc (Zn), calcium (Ca), iron (Fe), chrome (Cr), magnesium (Mg), potassium (K), copper (Cu) and cadmium (Cd) levels were identified in the liver samples at the end of the application. The results of the study suggest that exercise and CAPE fortification in rats cause changes in the Na, Zn, Ca, Fe and Cr parameters in liver tissues, and it does not affect Cd, Cu, Mg and K element distribution. It is thought that CAPE fortification would be helpful for preserving those parameters whose levels are known to be changing with exercise. © 2015, Springer Science+Business Media New York

Oleuropein alleviates malathion-induced oxidative stress and DNA damage in rats

The effects of acute exposure to 250 mg/kg malathion and the protective effects of 20 mg/kg oleuropein, both administered intraperitoneally, were evaluated in Wistar male rats. Malathion administration increased malondialdehyde, nitric oxide, 8-hydroxy-2?-deoxyguanosine, total oxidant status, and DNA damage, yet decreased total antioxidant activity, superoxide dismutase, and catalase activities in blood, liver, and kidney. Administration of oleuropein reversed malathion-induced oxidative stress, lipid peroxidation, DNA damage, and antioxidant enzyme activity. © 2015 Taylor & Francis