replacement of a tractor is an influential factor affecting timely farm operation. the accurate prediction of repair and maintenance costs is essential to selection of a replacement model. this study used empirical data for 60 two-wheel drive (2wd) tractors from astan ghods-e razavi agroindustry. the types and numbers of tractors used were the massey ferguson 285 (17), fiat (10), john deere 314...

deterioration of concrete structures in the gulf region is a serious problem. penetration of chloride ion into concrete is responsible for such early deterioration. determination of chloride diffusion coefficient is an effective way to predict the service life of concrete structures. in order to investigate the performance of concrete mixtures in such environments, ordinary and silica fume conc...

background and purpose: heart disease death rates have increased worldwide.family-oriented empowerment model improves the quality of life in the patients with chronic diseases. this study aims to determine the effect of family-oriented empowerment model on the life quality of the patients undergoing coronary artery bypass graft. methods: a quasi-experimental study was performed on the patients ...

the complex system containing n elements, each having three dependent components are described. the reliability and mean residual life of such systems with intact components at time t are investigated using a trivariate binomial model. considering a farlie-gumbel-morgenstern family, some graphical representations are given.

background: air pollution in tehran, capital of iran is responsible for several diverse negative effects. it has been estab­lished that air pollution can affect human health. these health effects include increased hospital admissions due to the ex­acerba­tion of cardiac and respiratory diseases, as well as symptoms such as headache, cough, eye irritation, nausea, sputum and even death in the mo...