Application of impact energy absorption systems in different industries especially in automotive industries as a solution to minimize the effect of impact onto the travelers and increasing car safety is especially significant. In order to increase the car security in accidents and incidents of cars, several efforts have been done by corporations. For this purpose, different energy absorption systems have been utilized. From all of them, thin-walled tubes due to lightness, high value of energy absorption capacity, long crushing length, and high ratio of energy absorption into weight have everincreasing application as one of the effective energy absorption systems. In this research, by carrying out experiments and finite element simulations, crushing manner, energy absorption value, mean crushing load, and initial buckling load of grooved thin-walled tubes with different geometric dimensions have been investigated and compared. Simulation of tested specimens has been executed in three-dimensional model by explicit method. Experimental and simulation results have a correlation. Results demonstrate that crushing manner and absorbed energy value in axial crushing of grooved thin-walled tubes could be controlled by introducing different groove distances.

Permeability is a key parameter that affects fluids flow in reservoir and its accurate determination is a significant task. Permeability usually is measured using practical approaches such as either core analysis or well test which both are time and cost consuming. For these reasons applying well logging data in order to obtaining petrophysical properties of oil reservoir such as permeability and porosity is common. Most of petrophysical parameters generally have relationship with one of well logged data. But reservoir permeability does not show clear and meaningful correlation with any of logged data. Sonic log, density log, neutron log, resistivity log, photo electric factor log and gamma log, are the logs which effect on permeability. It is clear that all of above logs do not effect on permeability with same degree. Hence determination of which log or logs have more effect on permeability is essential task. In order to obtaining mathematical relationship between permeability and affected log data, fitting statistical nonlinear models on measured geophysical data logs as input data and measured vertical and horizontal permeability data as output, was studied. Results indicate that sonic log, density log, neutron log and resistivity log have most effect on permeability, so nonlinear relationships between these logs and permeability was done.