m. mojtahedi

New alloys of aluminum piston alloy made by adding more nickel to their usual composition. Bulk-forming of new alloys at ambient temperature by conventional methods is not possible. Therefore, the hot-compression deformation behavior of these alloys has been studied in this study. Based on the true stress-strain graphs obtained from the experiments, the constitutive model proposed for these alloys based on the Johnson-Cook model. Then this model is improved by considering the coupled effects of the parameters. The accuracy of the proposed models has been investigated using appropriate statistical analysis, and as a result, the accuracy of the presented models has been confirmed. The modified model, compared to original model, in addition to the higher accuracy, can predict the trend of changes in flow stress. The study of variations of the model coefficients shows that with an increasing nickel content in the alloy composition, the strength and the flow stress of the alloys increased intensely at all temperatures and strain rates. Also, by increasing the amount of nickel, the effect of the strain rate on flow stress is reduced.

Different maintenance policies, including preventive maintenance and predictive maintenance, are introduced to enhance the execution of systems. Maintenance professional experts have faced numerous challenges with distinguishing the proper maintenance policy, among which causes of failure, accessibility, and the capability of maintenance should be regarded seriously. Moreover, most organizations do not have a deliberate and compelling model for evaluating maintenance policies under uncertainty to deal with real-world conditions. The aim of this paper is to introduce a new interval-valued fuzzy (IVF) decision model for the selection of maintenance policy based on order inclination with comparability to ideal solutions by Monte Carlo simulation. This paper introduces novel separation measures and a new IVF-distinguish index via possibilistic statistical concepts (PSCs) which can assist maintenance decision makers to rank maintenance policy candidates. Also, resilience engineering (RE) factors are considered along with conventional evaluation criteria. Finally, the steps of the proposed IVF model-based PSCs are applied to survey a real case in manufacturing industry. Results of the presented model are compared with the recent literature and could help maintenance personnel in identifying the best policy systematically.

In order to investigate the effect of isolated enterococcus facuim from intestine of Coracias Garrulus (EF) and lactofeed with two methods of spraying and drinking on performance, carcass characteristics, blood parameters, immune response, ceca microflora and jejunal morphology of BobWhite quail were done. A total of 420 chicks were arranged into 35 experimental pen with 7 treatments in a completely randomized design. The treatments were the control, the spraying, the drinking and spraying+drinking of enterococcus facuim, and the spraying, the drinking and the spraying+drinking of Lactofeed groups. A solution of 1011 CFU was used on days 1, 10 and 24 of age for spraying and drinking. Adding the same spraying and drinking EF or lactofeed reduced FCR (2.71 vs. 2.51) and increased body weight (395.67 vs. 307.88) in quail (P<0.05). The lowest abdominal fat percentage (0.725 vs. 23.14%) and highest weight of bursa of fabricus (0.78 vs. 0.62) in the quail = was belonged to the combination of spraying and drinking EF group. Lactofeed or EF reduced the concentration of cholesterol (249 vs. 342 mg/dl), LDL (211 vs. 148 mg/dl), triglyceride (173 vs. 268 mg/dl) and aspartate aminotransferase enzyme activity (256 vs. 192 U/L), but HDL concentration enhanced (96.16 vs. 67.44 mg/dl). In both methods of spraying and drinking, the EF improved immune responses to SRBC as compared to the control (9.33 vs 6.66) (P<0.05). Both of Lactofeed and EF improved the lactobacilli population of the ceca and morphology of jejunum. Therefore, the addition of enterococcus facuim isolates (EF) and lactofeed with the method of combination spraying and drinking may improve the performance, ceca flora, jejunum morphology, immune response and decreases the abdominal fat, blood lipids.