PENGEMBANGAN ALAT LATIHAN KETEPATAN SASARAN FOREHAND DRIVE PADACABANG OLAHRAGA TENIS LAPANGAN TAHUN 2021

Tennis court is a small ball game. Playing tennis court is a sport that is almost the same as playing table tennis and badminton, having the same goal of hitting the ball over the net so that it reaches the opponent's area. The game of tennis court is played by one or a pair of players facing across the net. This research is aimed at developing forehand drive training aids in tennis athletes. Forehand drive training aids in tennis court are first validated by 6 experts, 2 material expert in sports, 2 expert in the field of equipment / media, 2 expert field coach. The results of the small group trial involved 3 experts, 1 material expert with an assessment result of 85%, 1 trainer expert 84% and 1 media expert 85% it can be concluded that they meet the criteria to be continued in large group trials. It can be concluded that the results of large group trials meet the criteria to be used in assisting forehand drive exercises in tennis court

NUMERICAL STUDY OF HEAT TRANSFER ENHANCEMENT BY INSERTING DIFFERENT SIZE BALLS INSIDE TUBE

In this paper, the challenge is to increasing of the heat exchanger performance by placing different size balls inside the tubes. the development of previous studies to enhance relatively bad case of heat transfer where the inserting (a large ball and then a small ball) to collide the water molecules in the ball and generate turbulent flow (Reynolds number range from 50,000 to 350,000) and thus increase the thermal performance due to collision of particles with the inner casing of the tube and reduce the stagnation near the wall. The usefulness of small ball, after the big ball, is Reduce of gets wake flow. A simulation was made when changing the diameter ratio of big to small ball (Dr = 3, 4, 5). Also, the distance between the big ball and the small ball was changed (X = 2, 3, 5) mm. It was concluded that the best ball diameter ratio and best Distance is (Dr= D_b/D_sb = 5), (X = 3 mm), respectively. The pressure drop acts as a side effect of enhancement. Therefore, the method of equal pumping was adopted. The average thermal performance factor (TPF=1.178) of tube with insert the balls enhanced by 17.8% at (x=3mm) and (Dr=5) when compared with smooth tube.

Zero-free neighborhoods around the unit circle for Kac polynomials

In this paper, we study how the roots of the Kac polynomials $$W_n(z) = \sum _{k=0}^{n-1} \xi _k z^k$$ W n ( z ) = ∑ k = 0 n - 1 ξ k z k concentrate around the unit circle when the coefficients of $$W_n$$ W n are independent and identically distributed nondegenerate real random variables. It is well known that the roots of a Kac polynomial concentrate around the unit circle as $$n\rightarrow \infty $$ n → ∞ if and only if $${\mathbb {E}}[\log ( 1+ |\xi _0|)]<\infty $$ E [ log ( 1 + | ξ 0 | ) ] < ∞ . Under the condition $${\mathbb {E}}[\xi ^2_0]<\infty $$ E [ ξ 0 2 ] < ∞ , we show that there exists an annulus of width $${\text {O}}(n^{-2}(\log n)^{-3})$$ O ( n - 2 ( log n ) - 3 ) around the unit circle which is free of roots with probability $$1-{\text {O}}({(\log n)^{-{1}/{2}}})$$ 1 - O ( ( log n ) - 1 / 2 ) . The proof relies on small ball probability inequalities and the least common denominator used in [17].

Pemilihan Materi Pembelajaran PJOK oleh Guru Pendidikan Jasmani Olahraga dan Kesehatan di SMA Sederajat

The purpose of this study was to determine the selection of physical and health physical education learning materials in class X by PJOK teachers and determine the constraints or obstacles that occur in the learning process. This study uses a quantitative descriptive survey research method with research subjects 6 high school class X PJOK teachers equivalent in Turen District. Data collection used using non-test instruments, namely questionnaires and interviews. Research data from questionnaire items were changed to percentage form. The percentage of basic competence of large ball games is 60 percent, the percentage of small ball games is 31 percent, the athletic percentage is 46 percent, the percentage of martial arts is 12.5 percent, the percentage of physical fitness is 42 percent, the percentage of dexterity exercises get a percentage of 39 percent, the percentage of rhythmic gymnastics 17 percent, the percentage of water activity is 19 percent, the percentage of a healthy lifestyle results in a percentage of 58 percent, the percentage of drug and drug hazards is 68 percent. It was concluded that the PJOK teachers of class X in Turen sub-district as a whole had "chosen" the material to be taught but the learning was adapted to the facilities and infrastructure, and teacher competence. Abstrak: Tujuan penelitian ini adalah untuk mengetahui pemilihan materi pembelajaran pendidikan jasmani olahraga dan kesehatan di kelas X oleh guru PJOK dan mengetahui kendala atau hambatan yang terjadi dalam proses pembelajarannya. Penelitian ini menggunakan metode penelitian survei deskriptif kuantitatif dengan subjek penelitian 6 guru PJOK kelas X tingkat SMA sederajat Se Kecamatan Turen. Pengumpulan data yang digunakan menggunakan instrumen non tes yaitu angket dan wawancara. Data hasil penelitian dari butir-butir angket diubah menjadi bentuk persentase. Persentase kompetensi dasar permainan bola besar sejumlah 60 persen, persentase permainan bola kecil sejumlah 31 persen, persentase atletik sejumlah 46 persen, persentase beladiri sejumlah 12.5 persen, persentase kebugaran jasmani sejumlah 42 persen, persentase senam ketangkasan mendapatkan hasil persentase sejumlah 39 persen, persentase senam ritmik sejumlah 17 persen, persentase aktivitas air sejumlah 19 persen, persentase pola hidup sehat mendapatkan hasil persentase sejumlah 58 persen, persentase bahaya narkoba dan napza sejumlah 68 persen. Disimpulkan bahwa guru PJOK kelas X Se Kecamatan Turen secara keseluruhan “telah memilih” materi yang akan diajarkan namun pembelajaran menyesuaikan dengan sarana dan prasarana, dan kompetensi guru.

Discriminant Analysis: Impact of the Number of Repetitions on the Effectiveness of Teaching Boys Aged 7 Throwing a Small Ball

The aim of the study was to determine the impact of the number of repetitions on the effectiveness of teaching boys aged 7 throwing a small ball. Materials and methods. The study participants were 27 boys aged 7, who were randomly divided into three groups of 9 people each. The children and their parents were informed about all the features of the study and gave their consent to participate in the experiment. The study examined the impact of the number of repetitions on the effectiveness of teaching boys aged 7 throwing a small ball at a target. A pedagogical experiment studied the impact of 6, 12, and 18 repetitions with a 60-second rest interval on the increase in the level of proficiency in exercises of boys aged 7. In the first group, the boys repeated the task 6 times with a rest interval of 60 s, in the second group – 12 times with a rest interval of 60 s, in the third group 18 times with a rest interval of 60 s. When teaching throwing exercises during the class, the study assessed the level of proficiency by the alternative method (“performed”, “failed”) and calculated the probability of exercise performance (p = n/m, where n is the number of successful attempts, m is the total number of attempts). In teaching boys aged 7, the method of algorithmic instructions was used. The next exercise started after three successful attempts. Throwing a ball at a vertical target was taught. The study materials were processed by the IBM SPSS 20 statistical analysis software. During discriminant analysis, a prognostic model for group membership was created. Results. Discriminant analysis made it possible to determine the impact of the number of repetitions on the effectiveness of developing the skills of throwing a small ball at a target; to answer the question as to how significantly the modes of repetition differ by the effectiveness of motor skills development, to which class the object belongs based on the values of discriminant variables. Conclusions. Based on the analysis of group centroids, it was found that 12 repetitions of the exercise (6 sets 2 time each with a rest interval of 60 s) significantly influence the increase in the level of proficiency in physical education classes. The results of group classification show that 94.4% of the original grouped observations were classified correctly.

Asymptotic behavior of a class of perturbed differential equations

UDC 517.9 This paper deals with the problem of stability of nonlinear differential equations with perturbations. Sufficient conditions for global uniform asymptotic stability in terms of Lyapunov-like functions and integral inequality are obtained. The asymptotic behavior is studied in the sense that the trajectories converge to a small ball centered at the origin. Furthermore, an illustrative example in the plane is given to verify the effectiveness of the theoretical results.

On the three ball theorem for solutions of the Helmholtz equation

Let $$u_{k}$$ u k be a solution of the Helmholtz equation with the wave number k, $$\varDelta u_{k}+k^{2} u_{k}=0$$ Δ u k + k 2 u k = 0 , on (a small ball in) either $${\mathbb {R}}^{n}$$ R n , $${\mathbb {S}}^{n}$$ S n , or $${\mathbb {H}}^{n}$$ H n . For a fixed point p, we define $$M_{u_{k}}(r)=\max _{d(x,p)\le r}|u_{k}(x)|.$$ M u k ( r ) = max d ( x , p ) ≤ r | u k ( x ) | . The following three ball inequality $$M_{u_{k}}(2r)\le C(k,r,\alpha )M_{u_{k}}(r)^{\alpha }M_{u_{k}}(4r)^{1-\alpha }$$ M u k ( 2 r ) ≤ C ( k , r , α ) M u k ( r ) α M u k ( 4 r ) 1 - α is well known, it holds for some $$\alpha \in (0,1)$$ α ∈ ( 0 , 1 ) and $$C(k,r,\alpha )>0$$ C ( k , r , α ) > 0 independent of $$u_{k}$$ u k . We show that the constant $$C(k,r,\alpha )$$ C ( k , r , α ) grows exponentially in k (when r is fixed and small). We also compare our result with the increased stability for solutions of the Cauchy problem for the Helmholtz equation on Riemannian manifolds.