We consider a no-wait m-machine flowshop scheduling problem which is common in different manufacturing industries such as steel, pharmaceutical, and chemical. The objective is to minimize total tardiness since it minimizes penalty costs and loss of customer goodwill. We also consider the performance measure of total completion time which is significant in environments where reducing holding cost is important. We consider both performance measures with the objective of minimizing total tardiness subject to the constraint that total completion time is bounded. Given that the problem is NP-hard, we propose an algorithm. We conduct extensive computational experiments to compare the performance of the proposed algorithm with those of three well performing benchmark algorithms in the literature. Computational results indicate that the proposed algorithm reduces the error of the best existing benchmark algorithm by 88% under the same CPU times. The results are confirmed by extensive statistical analysis. Specifically, ANOVA analysis is conducted to justify the difference between the performances of the algorithms, and a test of hypothesis is performed to justify that the proposed algorithm is significantly better than the best existing benchmark algorithm with a significance level of 0.01.

Detecting how a cutout affects the critical buckling load in circular cylindrical shell is a serious issue for the design of the shells used in marine structures, aerospace and automobile applications. In this paper, buckling behavior of aluminum cylindrical shell with rectangular cutout, subjected to axial pressure was studied by means of finite element simulations. The effects of geometric parameters (R, t, a, b and L) on the first buckling mode capacity of the shell were studied. The effects of these factors and their interaction effects were investigated by combined numerical and statistical analysis. The results show that R/b, t and Rt/b were the main effective factors of critical buckling load. Based on the statistical analysis, a model for prediction of the critical buckling load was obtained with an accuracy equal to 95% (R2, R2 (pred) and R2 (adj)). This equation could be used to predict the critical buckling load of an isotropic circular shell with a rectangular cutout.

Nowadays, wage and salary system form the most important issues in any society, and its phenomenon takes dimensions with an expansion of a public organization and NGOs. Organizations provide employees satisfaction through different pay programs, which force them to work down more with higher quality. In this paper, we consider a survey of the payment system in an Iranian university as a case study. The population of this study consists of the existing documents, observations, working managers, supervisors and experts. This study is carried out from the desired community based on the data collected for a period of 18 months and the sample size is about 97 people. We use descriptive statistics to analyze the descriptive data. We also use the one-sample Kolmogorove-Smirnov test, t-test and Friedman test for the questions. The results of the existing payment system show that there is no any good condition and the employee & apos; s attitude towards this system are negative based on the collected data. Finally, some suggestions are recommended to improve the existing situation.