The study of biomechanical indicators in the arc of the run and the upgrading stage is one of the important variables that affect the nature of the upgrading and thus affect the result of the race due to the importance of these stages and the consequent variables during the last steps. That’s why, the jump-trainings based on assistant means or body weight positively affect the step-time for each of the three steps in the acceleration arc. As well as, it focuses on the momentary strength of each step at this stage. It also significantly affects the speed of motor performance to suit the activity in which the runner needs to perform perfect steps with high flow in order to convert the horizontal speed to a vertical one. This is achieved through producing high instantaneous power and in a short time to achieve a perfect elevation. Those trainings must be built according to real indicators based on scientific results to know the nature of these time-characteristics and the range of its impact on the variables of the last three steps and upgrading, because these variables depend on performance and accuracy and need to stability in performance during attempts. Therefore, some biomechanical variables are found for the three steps and the stage of upgrading through the use of video graphing, kinetic analysis, and preparing special trainings to develop these variables in order to solve this problem that faces the players of the country right now. The research was applied on a group of high-jump players from the country for the (6) advanced-level players and the results of the preceding and following tests were compared. The researchers concluded that the exercises which were performed by using the means and equipment according to the performance and which were used within the strength-exercises are effective in developing the pushing-time at the moments of contact for the last three steps and the stage of upgrading. In the same way, they are effective in the right-time strength of the performance-nature which helped in the frugality of time, the force spent correctly, and the interconnection of the parts of the correct performance of these variables in the last three steps. This is reflected on the stage of upgrading and led to its development.
Mass transfer has been studied at rotating cylinder electrodes fabricated with spiral-wound woven-wire meshes using reduction of copper as a test reaction. The experimental data were correlated by an empirical expression between the Sherwood number and the Reynolds number, both regarding the hydraulic diameter as a characteristic length. It was found that the Sherwood number was dependent upon the Reynolds number to the power of 0.521. An enhancement factor was adopted to compare the efficiency of the new rotating cylinder electrode with previous three-dimensional rotating cylinder electrodes. The results showed that the new type has a mass-transfer enhancement factor 2.3 times higher than those obtained with smooth rotating cylinder electr
... Show MoreThis systematic review aimed to investigate the relation between orthodontic treatment (OT) and the incidence of the gingival black triangle (GBT) after completing treatment with a fixed orthodontic appliance, as well as the associated risk factors and the level of alveolar bone. Electronic and hand searches were conducted in three electronic databases for relevant articles published up to March 2022. Retrieved articles went through a two-step screening procedure, and the risk of bias (RoB) was assessed by the Joanna Briggs Institute checklists. The incidence of GBT after OT was set as the primary outcome, while the secondary outcomes were the risk factors associated with GBT and alveolar bone loss following OT. Out of 421 papers, 5
... Show MoreRapid worldwide urbanization and drastic population growth have increased the demand for new road construction, which will cause a substantial amount of natural resources such as aggregates to be consumed. The use of recycled concrete aggregate could be one of the possible ways to offset the aggregate shortage problem and reduce environmental pollution. This paper reports an experimental study of unbound granular material using recycled concrete aggregate for pavement subbase construction. Five percentages of recycled concrete aggregate obtained from two different sources with an originally designed compressive strength of 20–30 MPa as well as 31–40 MPa at three particle size levels, i.e., coarse, fine, and extra fine, were test
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