Author
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 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.
)
