تعد الرماية واحدة من الألعاب التي يقاس مستوى الانجاز فيها بالأرقام إذ ارتفعت الأرقام المسجلة بالنسبة لسلاح المسدس الهوائي حتى وصلت عند بعض الأبطال العالميين إلى الانجاز النهائي ، وقد لجأ المدربون إلى مختلف الطرق التدريبية, وان ضعف الثبات والتركيز هما اللذان يقودان إلى هبوط مستوى الانجاز في الرماية ، ولتحقيق التركيز والثبات المطلوبين أثناء الرمي يجب التدريب على مطاولة حمل السلاح التي تعد من أصعب تدريبات الرماية لما تحتاجه من صبر وقوة تحمل لفترة طويلة نسبياً ، والثبات ممكن أن يزول بوجود أي مؤثر خارجي أو داخلي قد يتعرض له الرامي كالأحوال الجوية المفاجئة إذا كان ميدان الرمي مفتوحاً أو تعرض الرامي إلى أي ضغط نفسي أو شد عضلي نتيجة التوتر والضغط ، ولمعالجة هذه الظروف لدى اللاعب اتجه المدربون إلى العمل على تهدئــة اللاعبيــن قبل البدء بالســباق أوالتدريـب على الرمي وذلك باستعمال وسائل متعـددة ومنــها بعض الأدويــة المهدئـــة وقســــم منها يدخــل ضمن قائمة (المنشطات المحظورة ) ويطلق عليهـا ( المهدئات ) إذ تعمل المهدئات على منع توتر اللاعب والتخفيف من الضغط النفسي والعصبي الذي يتعرض له نتيجة جو السباق أو ما يسمى حمى البداية التي قد تصيب بعض اللاعبين أو اغلبهم لعدم خوضهم عدد كافٍ من السباقات أو قلة الخبرة وبالتالي يفقد التركيز والثبات اللذين هما الركيزتان الأساسيتان للرمي أثناء السباق ، وتعمل المهدئات في هذه الحالة على تخفيف توتر اللاعب وبالتالي الرمي بثبات وهدوء وتحقيق الانجاز الأفضل, ولكن تبقى هذه الطرق غير قانونية ومحاطة بالمخاطر ، كما استعمل بعض المدربون مركبات أخرى للوصول إلى حالة الثبات غير المهدئات وهي الأدوية والمركبات التي تعمل على خفض نشاط القلب والدورة الدموية وتخفيف الضغط الدموي وتخفيف سرعة نبض القلب مما يساعد على التهدئة والثبات ، ولكن هذه الأدويــة ( كدواء الاتينولول ) ( ) يستخدم في علاج الضغط الدموي المرتفع وهو من الأدوية المحظورة التي تستخدم تحت ضوابط معينة .
The competitive environment influences the increase in exercise intensity and hence adds to the growth of training and practice. The study objective.to identify the effect of competitive speed exercises on the effectiveness of skill performance and speed of counterattack for junior boxers, as well as to know the rate of development for these variables.Materials and methods. The research sample consisted of twelve up-and-coming Al-Najda Sports Club players who participated in the national tournament and were selected with care. They were placed into two groups, control and experimental, with six boxers each in the control and experimental groups. The two groups were assigned identical weights on purpose, and their ages range from 15 to 16 ye
... Show MoreIn this paper, numerical and experimental studies on the elastic behavior of glass fiber reinforced polymer (GFRP) with stiffeners in the GFRP section's web (to prevent local buckling) are presented. The GFRP profiles were connected to the concrete deck slab by shear connectors. Two full-scale simply supported composite beams (with and without stiffeners) were tested under impact load (three-point load) to assess its structural response. The results proved that the maximum impact force, maximum deflection, damping time, and damping ratio of the composite beam were affected by the GFRP stiffeners. The experimental results indicated that the damping ratio and deflection were diminished compare
... Show MoreThis study presents an investigation about the effect of fire flame on the punching shear strength of hybrid fiber reinforced concrete flat plates. The main considered parameters are the fiber type (steel or glass) and the burning steady-state temperatures (500 and 600°C). A total of 9 half-scale flat plate specimens of dimensions 1500mm×1500mm×100mm and 1.5% fiber volume fraction were cast and divided into 3 groups. Each group consisted of 3 specimens that were identical to those in the other groups. The specimens of the second and the third groups were subjected to fire flame influence for 1 hour and steady-state temperature of 500 and 600°C respectively. Regarding the cooling process, water sprinkling was applied directly aft
... Show MoreAlO-doped ZnO nanocrystalline thin films from with nano crystallite size in the range (19-15 nm) were fabricated by pulsed laser deposition technique. The reduction of crystallite size by increasing of doping ratio shift the bandgap to IR region the optical band gap decreases in a consistent manner, from 3.21to 2.1 eV by increasing AlO doping ratio from 0 to 7wt% but then returns to grow up to 3.21 eV by a further increase the doping ratio. The bandgap increment obtained for 9% AlO dopant concentration can be clarified in terms of the Burstein–Moss effect whereas the aluminum donor atom increased the carrier's concentration which in turn shifts the Fermi level and widened the bandgap (blue-shift). The engineering of the bandgap by low
... Show MoreNuclear structure of 29-34Mg isotopes toward neutron dripline have been investigated using shell model with Skyrme-Hartree–Fock calculations. In particular nuclear densities for proton, neutron, mass and charge densities with their corresponding rms radii, neutron skin thicknesses and inelastic electron scattering form factors are calculated for positive low-lying states. The deduced results are discussed for the transverse form factor and compared with the available experimental data. It has been confirmed that the combining shell model with Hartree-Fock mean field method with Skyrme interaction can accommodate very well the nuclear excitation properties and can reach a highly descriptive and predictive power when investiga
... Show MoreSolar collectors, in general, are utilized to convert the solar energy into heat energy, where it is employed to generate electricity. The non-concentrating solar collector with a circular shape was adopted in the present study. Ambient air is heated under a translucent roof where buoyant air is drawn from outside periphery towards the collector center (tower base). The present study is aimed to predict and visualize the thermal-hydrodynamic behavior for airflow under inclined roof of the solar air collector, SAC. Three-dimensional of the SAC model using the re-normalization group, RNG, k−ε turbulence viscus model is simulated. The simulation was carried out by using ANSYS-FLUENT 14.5. The simulation
... Show MoreA microbubble air flotation technique was used to remove chromium ions from simulated wastewater (e.g. water used for electroplating, textiles, paints and pigments, and tanning leather). Experimental parameters were investigated to analyze the flotation process and determine the removal efficiency. These parameters included the location of the sampling port from the bottom of the column, where the diffuser is located to the top of flotation column (30, 60, and 90 cm), the type of surfactant (anionic, SDS, or cationic, CTAB) and its concentration (5, 10, 15, and 20 mg/L), the pH of the initial solution (3, 5, 7, 9, and 11), the initial contaminant concentration (10, 20, 30, and 40 mg/L), the gas flow rate (0.1, 0.2, 0.3, and 0.5 L/mi
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