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Mean Grain Size and Pore Effects οn Ultrasonic Properties οf WC-Fe-Ni and SiC-Fe-Ni Composites

100%

Sarpün İ., Özkan V., Yönetken A., Erol A.

In this work, electroless nickel plating technique was used with WC-Fe and SiC-Fe powders. Plated powders were sintered at temperature ranging from 600C to 1100C under argon shroud in Phoenix microwave furnace. The mean grain size is determined by using three different techniques namely ultrasonic velocity, ultrasonic attenuation, and rate of screen heights of successive peaks according to the pulse-echo method by using a 2 MHz and a 4 MHz probes compared with the scanning electron microscopy images. In addition, the relative effects of porosity on ultrasonic attenuation and velocity in the WC-Fe-Ni and SiC-Fe-Ni composite samples are studied. It is seen that the ultrasonic velocity, the ultrasonic attenuation, the rate of screen heights of successive peaks have a linear relation with the mean grain size of samples. However, the correlation coefficients of porosity graphs have higher values than mean grain size graphs for the composite materials as expected. This indicates that porosity determines the ultrasonic velocity and attenuation for the composite samples.

Comparison of Chosen Physical Fitness Characteristics of Turkish Professional Basketball Players by Division and Playing Position

88%

Köklü Y., Alemdaroğlu U., Koçak F., Erol A., Fındıkoğlu G.

Journal of Human Kinetics

2011

vol. 30

99-106

The purpose of the present study was to compare chosen physical fitness characteristics of Turkish professional basketball players in different divisions (first and second division) and playing positions. Forty-five professional male basketball players (14 guards, 15 forwards, 16 centers) participated in this study voluntarily. For each player, anthropometric measurements were performed, as well as a multi-stage 20 m shuttle run, isokinetic leg strength, squat jump (SJ), countermovement jump (CMJ), 10-30 meter single-sprint and T-drill agility tests. The differences in terms of division were evaluated by independent t-test and the differences by playing position were evaluated by one-way ANOVA with Post Hoc Tukey test. First division players' CMJ measurements were significantly higher than those of second division players' (p≤0.05), whereas second division players' 10 m sprint times were significantly better than those of first division players' (p≤0.05). In addition, forwards and centers were significantly taller than guards. Centers were significantly heavier and their T-drill test performances were inferior to those of forwards and guards (p≤0.05). Moreover, guards had a significantly higher maximal oxygen uptake (VO2 max) than centers. Guards and forwards showed significantly better performance in the 10 and 30 m sprint tests than centers (p≤0.05). Forwards and centers had significantly better left leg flexor strength at 180°.s-1(p≤0.05). In conclusion, the findings of the present study indicated that physical performance of professional basketball players differed among guards, forwards and centers, whereas there were not significant differences between first and second division players. According to the present study, court positions have different demands and physical attributes which are specific to each playing position in professional basketball players. Therefore, these results suggest that coaches should tailor fitness programs according to specific positions on the court.

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1 Acta Physica Polonica A

1 Journal of Human Kinetics

1 2013

1 2011

2 Erol A.

1 Alemdaroğlu U.

1 Fındıkoğlu G.

1 Koçak F.

1 Köklü Y.

1 Sarpün İ.

1 Yönetken A.

1 Özkan V.

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Mean Grain Size and Pore Effects οn Ultrasonic Properties οf WC-Fe-Ni and SiC-Fe-Ni Composites

Comparison of Chosen Physical Fitness Characteristics of Turkish Professional Basketball Players by Division and Playing Position