5 research outputs found
Pengaruh Pembelajaran Menggunakan Metode Bermain Permainan Bolavoli Gandu Level II Dan Bolavoli Mini Terhadap Hasil Belajar Keterampilan Passing Bawah Bolavoli Pada Siswa Kelas VII SMP Negeri 10 Kota Malang.
No full textPermainan bolavoli gandu adalah permainan memvoli bola yang diciptakan untuk mengembangkan kesegaran jasmani. Permainan bolavoli mini adalah permainan memvoli bola yang merupakan hasil modifikasi dari permainan bolavoli. Permasalahan yang dihadapi siswa kurang aktif dan umumnya kurang berminat dalam melakukan aktivitas jasmani khususnya permainan bolavoli karena kurangnya permainan ataupun modifikasi dalam pembelajaran bolavoli sehingga banyak siswa yang tidak maksimal dalam proses pembelajaran yang akan berdampak pada kurangnya peningkatan dan pengembangan tingkat keterampilan dalam hal bermain bolavoli. Agar pembelajaran bolavoli berjalan sesuai harapan, peneliti memberikan permainan bolavoli gandu level II dan bolavoli mini menggunakan metode bermain yang bertujuan untuk meningkatkan hasil belajar keterampilan passing bawah bolavoli pada peserta didik kelas VII SMP Negeri 10 Kota Malang.Tujuan dalam penelitian ini adalah:1) mengetahui pengaruh latihan bolavoli gandu level II menggunakan metode bermain terhadap hasil belajar passing bawah,2) mengetahui pengaruh latihan bolavoli mini menggunakan metode bermain terhadap hasil belajar passing bawah dan3) mengetahui perbedaan pengaruh latihan permainan bolavoli gandu level II dengan bolavoli mini menggunakan metode bermain terhadap hasil belajar passing bawah.Penelitian ini menggunakan metode eksperimen dengan rancangan two group, pretest, posttest, design pada kelompok bolavoli gandu level II dan bolavoli mini. Variabel bebas bolavoli gandu level II dan bolavoli mini menggunakan metode bermain, variabel terikatnya hasil belajar keterampilan passing bawah bolavoli. Subyek penelitian berjumlah 30 peserta didik kelas VII SMPN 10 Kota Malang. Teknik analisis data yang digunakan dalam penelitian ini adalah teknik analisis varians (anava) satu jalur dengan taraf signifikan α = 0,05.Berdasarkan hasil hipotesis menggunakan anava satu jalur diperoleh1) terdapat perbedaan rata-rata skor pretest 23.00 dan skor postest 27,73 hasil belajar passing bawah permainan bolavoli gandu level II menggunakan metode bermain dengan probabilitas 0,000 0.05. Dengan demikian tidak terdapat perbedaan pengaruh pembelajaran permainan bolavoli gandu level II dan bolavoli mini menggunakan metode bermain terhadap passing bawah bolavoli. Pembelajaran permainan bolavoli gandu level II dan permainan bolavoli mini dengan metode bermain tidak ada perbedaan pengaruh, maka permainan bolavoli gandu level II dan bolavoli mini menggunakan metode bermain dapat digunakan sebagai modifikasi permainan untuk meningkatkan hasil belajar keterampilan passing bawah bolavoli
Q‐switching pulses generation with samarium oxide film saturable absorber
No full textQ-switching pulses generation in an erbium-doped fiber laser (EDFL) was demonstrated by using a samarium oxide (Sm2O3) film as a saturable absorber (SA) for the first time. The passively Q-switched EDFL operated stably at 1567 nm with tunable repetition rates, ranging from 47 to 66 kHz with the increase in pump power from 51.0 to 88.1 mW. At 88.1 mW pump power, the maximum pulse energy and the minimum pulse width were obtained at 26 nJ and 5.6 μs, respectively. These results demonstrated that the proposed Sm2O3 SA is viable for the construction of a flexible and reliably stable Q-switched pulsed fiber laser in the 1.5 μm region. © 2019 Wiley Periodicals, Inc
Advanced 1-bit algorithmic approaches to PB phase metasurface optimization for radar cross-section reduction
No full textThe Pancharatnam-Berry (PB) metasurface has gained significant attention for its exceptional phase control capabilities. Various optimization techniques have been introduced, yielding diverse results even with the same unit cell design. We explored methods such as array pattern synthesis (APS) with particle swarm optimization (PSO), random sequence, specialized 0–1 coding, a genetic algorithm with a nonlinear fitting method, and PSO combined with far-field scattering and the annealing algorithm. Among these, the annealing algorithm demonstrated the most effective radar cross-section (RCS) reduction. The proposed design operates over a frequency range of 10–21.4 GHz, with a center frequency of 17 GHz. The 10 dB far-field RCS reduction bandwidth extends from 10.5 to 19.5 GHz, achieving a relative bandwidth of 52.94 % at normal incidence under linearly polarized normal incidence waves. For oblique incidence linear polarization, the metasurface maintains effective RCS reduction up to an incidence angle of 30°. The design utilizes unit cells with dimensions of 0.34λ × 0.34λ and a thickness of 0.145λ at the operating frequency. Experimental results closely match the simulated outcomes, validating the accuracy of the proposed design. Furthermore, compared to previously proposed methods, this approach demonstrates superior performance in bandwidth and RCS reduction. The coding metasurface comprises varying numbers of unit cells, with optimized configurations leading to low backscattering through mechanisms like polarization conversion, scattering and reflection. While the annealing algorithm demonstrates consistent RCS reduction (>10 dB) across the entire frequency spectrum, other coding strategies achieve < 10 dB reduction in specific bands. These findings illustrate the immense potential of the annealing algorithm for electromagnetic wave manipulation, with applications in stealth technology
Polarization-controlled coding metasurface with phase cancellation and diffusion for enhanced radar cross section reduction
No full textAbstract A novel metasurface design is presented integrating polarization conversion, diffusion, and phase cancellation mechanisms for broadband radar cross-section (RCS) reduction. The metasurface employs a rotationally symmetric configuration, enabling efficient dispersion of electromagnetic waves in x and y polarizations. By changing the unit cell size, polarization conversion optimization is accomplished. This results in a 180 phase difference for the 1-bit design and 22.5 for the 2-bit design, with reflection magnitudes surpassing 0.9 in the 11.2-20.2 GHz and 12.3-19.5 GHz frequency ranges, respectively. The genetic algorithm (GA) was employed to optimize the arrangement of unit cells, identifying the most effective configuration for scattering and RCS suppression. Simulation results under LP normal incidence demonstrate significant RCS reduction capabilities. The 1-bit metasurface achieves approximately 10 dB RCS reduction across 12.3-19.2 GHz, corresponding to a relative bandwidth of 43.81%. In contrast, the 2-bit metasurface achieves a 20 dB decrease inside 12-19.3 GHz (relative bandwidth 46.65%) and a wider 10 dB reduction over 11.1-20.3 GHz (relative bandwidth 58.60%), with a peak reduction of roughly 15 dB in the 13.5-15.4 GHz range. Additionally, co-polarized reflections produced by the Pancharatnam-Berry (PB) phase or unit cell rotation introduce continuous phase discrepancies, which aid in efficient wave manipulation. Under LP oblique incidence, the metasurface demonstrates robust performance. Over 12.3-18.9 GHz, the 1-bit design retains RCS reduction of 10 dB up to a 15 incidence angle (relative bandwidth 42.3%), while the 2-bit design extends this capability up to a 30 incidence angle across 12-19.3 GHz (relative bandwidth 46.65%). Both simulated and experimental results validate the metasurface’s ability to manipulate electromagnetic waves and achieve effective RCS reduction, highlighting its potential for advanced stealth and electromagnetic wave control applications
Conformal and Flexible Antennas in Ultra-High Frequencies: Prospects and Challenges for Partial Discharge Diagnostics
No full textWith the exponential increase in smart device usage across various domains, flexible and conformal antenna technologies have emerged as transformative solutions, enabling wireless systems in numerous smart applications. However, selecting a suitable flexible and conformal substrate remains challenging because of the intricate characteristics and performance considerations of each material. Additionally, most applications of these substrates are confined to specific areas, such as body-worn devices, biomedical uses, and health services. In contrast, the use of ultra-high frequency (UHF, 0.3–3 GHz) antennas is largely concentrated in radio frequency identification (RFID) and telecommunications, with limited exploration in other areas. Recently, UHF antennas have gained attention for unconventional applications, including high-voltage (HV) defect detection, particularly partial discharge (PD) diagnosis. However, practical challenges arise due to the rigidity of commercial substrate materials. This paper provides a comprehensive survey on flexible and conformal UHF antennas’ applicability for PD diagnostics, a field that remains underexplored. We systematically assess the electrical, mechanical, and thermal properties of various flexible and conformal substrates relevant to UHF antenna development. In this investigation, we thoroughly analyse five substrate materials, namely polyimide (PI), polydimethylsiloxane (PDMS), Rogers laminates, polytetrafluoroethylene (PTFE), and polyethylene terephthalate (PET), and several types of UHF antennas including planar monopole, spiral antenna, Hilbert antenna, biconical antenna, and so on. The synthesis of this research delivers a complete roadmap, addressing existing limitations and proposing future directions for PD diagnosis by conformal and flexible antennas
