Pembelajaran Mepergunakan Media Trainer Stand Sistem Pengapian Untuk Meningkatkan Hasil Pembelajaran Identifikasi Komponen Sistem Pengapian

Penelitian ini bertujuan mengetahui peningkatan hasil belajar siswa menggunakan media trainer stand sistem pengapian pada kompetensi mengidentifikasi komponen sistem pengapian dalam proses pembelajaran mata pelajaran kelistrikan otomotif. Penelitian menggunakan metode eksperimen dengan Pretest Posttest Control Group Design, tes sebagai alat pengumpul data. Populasinya adalah siswa kelas XI jurusan Teknik Sepeda Motor SMK Negeri 1 Kandeman tahun ajaran 2012/2013, terdiri dari 1 kelas dengan jumlah 35 siswa dan digunakan semua sebagai sampel. Hasil penelitian menunjukkan Berdasarkan hasil uji hipotesis menggunakan analisis uji-t didapat thitung 20,29 dan ttabel 1,609, nilai rata-rata sebelum 71,07 meningkat menjadi 78,98 setelah perlakuan. Dengan demikian dapat disimpulkan bahwa penggunaan media trainer stand sistem pengapian lebih mudah untuk dipahami dibandingkan dengan pembelajaran yang tidak mempergunakan media trainer stand pada mata pelajaran mengidentifikasi komponen sistem pengapian dengan adanya peningkatan hasil belajar siswa pada kompetensi mengidentifikasi komponen sistem pengapian setelah menggunakan media trainer stand sistem pengapian sebesar 7,86%

Pengaruh Rapat Arus Terhadap Ketebalan Dan Struktur Kristal Lapisan Nikel pada Tembaga

The effect of current density on thickness and crystal structures of the coatings in the electroplating of nickel on copper has been investigated. The electroplating of nickel was conducted at a voltage of 0.5 V for 10 minutes with varied current densities of 0.3 mA/cm2 ; 0.6 mA/cm2 ; 0.9 mA/cm2 ; and 1 mA/cm2 . The nickel coatings werw tested by thickness measurement and crystal structures determination. The experimental results showed that the thickness of the nickel coatings increased as the current density increased. The XRD characterization of the nickel coatings revealed the diffraction patterns for cubic structures with orientation of (111) and (200). As the current density increases, the crystal with (111) and (200) orientation tends to be formed more lagely. Key Words: electroplating, thickness, crystal structur

Kajian Variasi Suhu Annealing Dan Holding TIME Pada Penumbuhan Lapisan Tipis Bazr0,15ti0,85o3 Dengan Metode Sol Gel

Penumbuhan lapisan tipis BaZr0,15Ti0,85O3 telah dilakukan menggunakan metode sol gel di atas substrat Pt/Si yang disiapkan dengan spin coater. Penumbuhan lapisan tipis menggunakan variasi suhu annealing 8000C dan 9000C, dan variasi waktu tahan (holding time) 3 jam dan 4 jam dengan kecepatan putar 4000 rpm. Hasil karakterisasi XRD menunjukkan, seiring dengan bertambahnya waktu tahan menunjukkan bertambahnya intensitas yang semakin tinggi. Hal ini menandakan tingkat kekristalan makin tinggi. Namun, dengan penambahan suhu annealing maka intensitas semakin kecil. Setelah dilakukan penghalusan menggunakan metode Rietveld dengan program GSAS, parameter kisi lapisan tipis BaZr0,15Ti0,85O3 semakin besar dengan bertambahnya suhu annealing dan waktu tahan serta memiliki struktur kristal tetragonal. Partikel size yang didapat dengan formula Scherer semakin besar seiring dengan bertambahnya suhu annealing dan waktu tahan. Hal ini juga ditunjukkan dari SEM, ukuran butir semakin besar seiring dengan bertambahnya suhu annealing, akan tetapi pada varisi suhu annealing ukuran butir tidak dapat ditentukan. Thin Films BaZr0,15Ti0,85O3 have deposited on Pt/Si substrate by using sol gel method that was prepared by using spin coater. Deposition of thin films applies by using annealing temperatures in 8000C and 9000C, while the holding time was 3 and 4 hours and the rotation speed was 4000 rpm.The XRD characterization results show that the x-ray intensity increases along with the increasing of its holding time therefore it indicates that the crystallinity level is higher. Meanwhile the x-ray intensity decreases along with the increasing of annealing temperature. The refinement results using the Rietveld method with the GSAS program show that the thin films BaZr0.15Ti0.85O3 have tetragonal crystal structure and its lattice parameter value increases along with the increasing of its annealing temperature and holding time. Particle size obtained by Scherer formula was increasing along with the increasing of the annealing temperature and holding time. It was also shown from the SEM characterization results that the particle size increased along with the increasing of the annealing temperature but the grain size variation cannot determined

Antimony-doped graphene nanoplatelets

Heteroatom doping into the graphitic frameworks have been intensively studied for the development of metal-free electrocatalysts. However, the choice of heteroatoms is limited to non-metallic elements and heteroatom-doped graphitic materials do not satisfy commercial demands in terms of cost and stability. Here we realize doping semimetal antimony (Sb) at the edges of graphene nanoplatelets (GnPs) via a simple mechanochemical reaction between pristine graphite and solid Sb. The covalent bonding of the metalloid Sb with the graphitic carbon is visualized using atomic-resolution transmission electron microscopy. The Sb-doped GnPs display zero loss of electrocatalytic activity for oxygen reduction reaction even after 100,000 cycles. Density functional theory calculations indicate that the multiple oxidation states (Sb3+ and Sb5+) of Sb are responsible for the unusual electrochemical stability. Sb-doped GnPs may provide new insights and practical methods for designing stable carbon-based electrocatalystsclose0

Desain Dan Penerapan Media Berbasis Adobe Flash Professional Cs5 Untuk Meningkatkan Hasil Belajar Siswa Pada Pembelajaran Kompetensi Memelihara/servis Sistem Ac

Penelitian ini bertujuan menerapkan media berbasis adobe flash professional cs5 untuk meningkatan nilai siswa pada pembelajaran kompetensi memelihara/servis sistem AC (Air Conditioner). Populasi penelitian ini adalah siswa kelas XI TKR SMK Negeri 2 Demak yang terdiri dari 3 kelas dengan jumlah 103 siswa. Sampel diambil dengan metode purposive sample, kemudian diperoleh 2 kelas, 1 kelas sebagai kelompok kontrol yang berjumlah 34 siswa dan 1 kelas sebagai kelompok eksperimen yang berjumlah 34 siswa. Pengumpulan data menggunakan metode dokumentasi dan metode tes. Hasil analisis data mendapatkan bahwa ada peningkatan hasil belajar siswa antara sebelum menerapkan dan setelah menerapkan media berbasis adobe flash professional cs5. Kelas eksperimen memiliki rata-rata pre test sebesar 56,07 dan kelas kontrol 57,54. Dari data tersebut terlihat bahwa kemampuan awal dari masing-masing kelas terlihat sama. Hasil belajar siswa setelah pembelajaran dicari melalui post test dan didapatkan rata-rata kelas eksperimen sebesar 78,13 dan kelas kontrol sebesar 69,80

Hole mobility in AlₓGa₁₋ₓSb grown by metalorganic chemical vapour deposition

The temperature dependence of the hole mobilities of AlₓGa₁₋ₓSb films in the regime 0≤x≤0.25 has been examined by Van der Pauw-Hall measurements. The films have been grown by metalorganic chemical vapor deposition on Si-GaAs substrates using TMA1, TMGa, and TMSb precursors. The mobility decreases sharply when a small amount of A1 in the range 0 100 K), the same effect was due to lattice phonon scattering. At 300 and 77 K, the alloy scattering is the most important mechanism in AlₓGa₁₋ₓSb ternaries, however the temperature dependence of alloy scattering is less pronounced as the temperature decreases.6 page(s

GaSb/AlGaSb compound semiconductors grown by MOCVD for optoelectronic applications

AlₓGa₁−ₓSb films in the regime 0 ≤ x ≤ 0.30 have been grown by metalorganic chemical vapor deposition on GaAs and GaSb substrates using TMAl, TMGa and TMSb precursors. We report the effects of growth conditions on the optical properties. Samples grown at temperatures of 540°C, 580°C and 600°C and a V/III ratio of 1 have been investigated. The AlₓGa₁−ₓSb layers grown at 580°C and 600°C with a V/III ratio of 1 and Al content in the range of 0.5% to 25% were found to exhibit excellent optical quality with a very high optical transmission at energies below the bandgap. The principle photoluminescence features observed are attributed to bound exciton and donor-acceptor transitions with FWHM comparable to the best values reported elsewhere.7 page(s

X-ray photoelectron spectroscopy of Alx Ga1-xSb grown by metalorganic chemical vapour deposition

The extent of oxidation and growth derived oxygen contamination for Al₀.₀₅Ga₀.₉₅Sb grown by metalorganic chemical vapour deposition (MOCVD) were systematically investigated by X-ray photoelectron spectroscopy (XPS) using a system with high-energy resolution. The Sb3d₅/₂ and O1s peaks are well resolved and the Ga3d peaks are also well resolved. As expected, all samples investigated show oxide layers (Al₂2O₃, Sb₂O₂ and Ga₂O₅) on their surfaces. In particular the percentage of aluminium-oxide was very high compared with a small percentage of AlSb. This indicates that the surface aluminium is very reactive to oxygen from the environment. Carbon content on the surface was also very high. Deeper into the layer, the carbon signal was below the detection limit of XPS and secondary ion mass spectroscopy (SIMS) indicating that the carbon was due to atmospheric exposure. The results indicate extremely low carbon content for Al₀.₀₅Ga₀.₉₅Sb epilayers grown using TMAl, TMGa and TMSb as metalorganic precursors in an MOCVD system.4 page(s

Study of optical and electrical properties of AlxGa1-xSb grown by metalorganic chemical vapor deposition

AlxGa1-xSb films in the regime 0x0.25 have been grown by metalorganic chemical vapor deposition on GaAs and GaSb substrates using TMAl, TMGa, and TMSb precursors. We report growth conditions and film properties, including the effect of V/III ratio and growth temperature on electrical and optical properties. Growth temperatures in the range of 520°C and 680°C and V/III ratios from 1 to 5 have been investigated. All epilayers grown exhibit p-type behavior. The mobility decreases and the carrier concentration increases sharply when a small amount of Al is incorporated into GaSb. The sharp cutoff and Fabry-Perot oscillations of the transmission spectra of the AlGaSb layers confirm the high quality of the films. The principle photoluminescence features observed are attributed to bound exciton and donor-acceptor transitions with FWHM comparable to the best values reported elsewhere.7 page(s