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Abstrak :
ABSTRAK
Ilmu fabrikasi mikro merupakan ilmu yang saat ini sangat penting untuk dikembangkan. Salah satu metode yang dikembangkan dalam bidang fabrikasi mikro adalah biomachining. Proses ini menggunakan jenis bakteri yang dapat memproses logam, salah satunya adalah bakteri Acidithiobacillus ferrooxidans. Penelitian yang telah dilakukan menunjukkan bahwa bakteri Acidithiobacillus ferrooxidans dapat memproses material tembaga dengan struktur kristal polycrystalline. Karakterisasi profil permukaan benda kerja hasil biomachining pada tembaga polycrystalline juga telah mendapatkan hasil yang jelas. Pada penelitian ini, proses biomachining dilakukan pada tembaga jenis polycrystalline dan single crystal untuk mengetahui perbedaan karakteristik profil permukaan yang dihasilkan. Benda kerja diberi pola 3 buah channel dengan lebar 500 μm menggunakan proses photolithography dan dimasukkan ke dalam kultur bakteri Acidithiobacillus ferrooxidans agar terjadi proses biomachining. Proses ini dilakukan dengan variasi waktu total pemakanan yaitu selama 12 jam, 24 jam, 36 jam, dan 48 jam. Data profil permukaan diperoleh menggunakan alat ?SURFCOM?, mikroskop ?Dino-Lite? dan SEM. Hasil dari penelitian ini adalah karakteristik profil permukaan hasil biomachining tembaga polycrystalline cenderung isotropic dan pada tembaga single crystal cenderung anisotropic. Hasil lain yang diperoleh dari penelitian ini antara lain nilai Ra yang terbukti berbeda signifikan, sedangkan MRR dan SMRR tidak signifikan perbedaannya

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ABSTRACT
Micro fabrication is a science that is very important to be developed. One of the methods developed in micro fabrication is biomachining. This process uses a type of bacteria that can process metal, one of which is Acidithiobacillus ferrooxidans bacteria. Research has shown that Acidithiobacillus ferrooxidans bacteria can process copper material with polycrystalline structure. Surface profile characteristic of the biomachined polycrystalline copper also has a clear result. In this study, biomachining process was done on polycrystalline and single crystal copper to find the difference of the resulting surface profile characteristic. The workpiece was coated with a pattern of 3 channels with a width of 500 μm using photolithography process and then dipped into Acidithiobacillus ferrooxidans bacterial culture for biomachining process. This process was carried out with total of 4 variations, 12 hours, 24 hours, 36 hours and 48 hours of machining time. Surface data was obtained using ?SURFCOM?, ?Dino-Lite? microscope, and SEM. The results of this study are the surface profile characteristics of the biomachined polycrystalline copper tends to be isotropic and single crystal copper tends to be anisotropic. Other results obtained from this study are the value of Ra is shown to vary significantly, while MRR and SMRR has insignificant differences.

Abstrak :
Modern technology for refrigerators and coolers is based on the chemical gas Chlorofluorocarbon (CFC) compression method that is indicative of a high consumption of electricity. The CFC is also understood as a reason for global warming. One of the solutions to this issue is magnetic refrigeration technology, which is environmentally friendly because it does not use any hazardous chemicals or ozone depleting/greenhouse gases. Magnetic refrigeration technology is based on the magnetocaloric effect of magnetic refrigerant materials. Exploring the magnetocaloric effect of magnetic refrigerant materials is important because these contain many of the physical properties needed for magnetic refrigeration technology. Herein, the present work reports on the magnetocaloric effect of La0.7Ca0.3Mn1?xSnxO3 (x = 0.0, x = 0.02 and x = 0.04) compound samples produced with the solid state reaction technique. Curie temperature TC obtained for the La0.7Ca0.3Mn1?xSnxO3 (x = 0.0, x = 0.02 and x = 0.04) are 260 K, 176 K and 170 K with -?SM max of 4.32 J×kg-1×K-1, 1.61 J×kg-1×K-1 and 1.24 J×kg-1×K-1 and a refrigerant capacity of 48 J/kg, 41.43 J/kg and 28.53 J/kg for x = 0.0, x = 0.02 and x = 0.04, respectively. A small addition of Sn-doped resulted in a significant decrease of more than 80 K on the Curie temperature scale compared to that of La0.7Ca0.3MnO3. The large gap in the decreasing magnetic temperature phase transition might be useful as an option of metal/transition metal doped for tuning the Curie temperature of magnetic refrigerant materials.

Abstrak :
ABSTRAK Photovoltaic PV adalah salah satu energi terbarukan yang telah berkembang dan menjadi sumber energi yang menanjikan untuk digunakan di perumahaan. Oleh karena itu tenaga surya mandiri ini menjadi solusi sebagai sumber listrik di daerah pedesaan, dimana daerah tersebut tidak terjangkau oleh PLN. Karenanya, desain PV sistem yang optimum harus dilakukan untuk mencari sistem perancangan array PV yang memiliki biaya terjangkau. Di penelitian ini dengan membandingkan 2 metode, maka metode yang optimal untuk mendesain tenaga surya mandiri akan di dapatkan.

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ABSTRACT Photovoltaic PV , one of renewable energy has grown to become one of the most promising energy source for residential use. There by, Stand alone photovoltaic system is a solution as power plant in rural area that is not reach by electicity provider. The stand alone photovoltaic system depends on the load profile, battery sizing, and PV sizing. Hence, an optimal PV sizing and Battery sizing should be investigated to result an affordable PV array that will influence the cost. There fore, by comparing two method, then an optimum method for photovoltaic stand alone can be obtained.