Azhar Hadi Mahdi
Abstract
Statistical and analysis researches are considered important in solving many problems, and taking suitable decisions, and sometimes predict incoming problems and solving them in near ...
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Statistical and analysis researches are considered important in solving many problems, and taking suitable decisions, and sometimes predict incoming problems and solving them in near or far future for specific sphere or to improve the productivity of any kind of product and other application. Response surfaces method roots goes back to 1930’s and is considered very important, its applications had a highly successful results in chemical engineering, agricultural, medical applications, biological, apart from, simulation in computers. The previous attempts to carry out these experiments according to linear and nonlinear models to estimate the parameters. This research has adopted the least square method in cases of linear regression and (Marquardt method) in case of nonlinear models which are distinguished with accurate parameters, also to solve multiple linear relationships problem between independent variables if it was exist. This method has been applied to study compressive strength for concrete in ages 3, 7, 28 days and the results were concluded from practical experiment according to complete random design (3*3) in bearing concrete (with standard specifications) compressive strength. In order to get minimum estimation for relationship between bearing concrete to compressive strength and independent variables represents by percentages (sand and gravel) and to fix water cement ratio. Experiments were varied each time percentage of sand and gravel and measure compressive strength for any age mentioned. Results have been analyzed statistically to find the best suitable model with high efficiency in application from the statistical models used in this research along with random design.
