Judul: Rancang Bangun Sistem Penggerak Kendaraan Air Berbasis Getaran Struktur
Abstrak: The use of oscillating fins (including its body) by aquatic animals for propulsion has inspired the design of marine propulsion system in this research. Many researchers studied structural vibration analysis for simulating vibration on building or bridge. Natural frequency has important role of the analysis. For instance, building or bridge will get the rupture point (microscopic) on that natural frequency with minimum energy. Therefore, it can be assumed that structural vibration at the natural frequency as propulsion system for water vehicle will decrease the consumption of energy. The aims of this research were to design a propulsion system for water vehicle using structural vibration, to simulate the model for the best material and frequency of vibration with low energy use, and to calculate the energy requirement through a model. Solidworks (software) and numerical analysis has been used for modeling and simulating the system. The best result at fixed hinge type showed that vibrating structure with 500 mm length, 30 mm width, and 0.5 mm thickness in the water can produce 0.99 N of thrust that can be used for moving the water vehicle model (with 0.72 m2 of wetted area) until the limit of velocity 0.79 m/s. The selected material was annealed stainless steel, because it has big number of elastic modulus and corrosion less.
Keyword: thrust, marine propulsion system, structural vibration, aquatic animals

Judul: Rancang Bangun dan Kinerja Aerator Tipe Kincir dengan Sudu Bergerak
Abstrak: To reduce operating costs, the power efficiency of paddle wheel aerator needs to be improved. The purpose of this study was to design a paddle wheel aerator with movable blades to reduce its rotation power requirement and produce the best aeration performance. In this aerator design, paddles were driven to open and close on hinges using cam-rods mechanism, in which the paddles opened while scooping up water, and closed when paddles were above the water surface. The aerator was rotated using an electric motor. Performance tests were carried out on a test pond, on operating depths of 4 and 6 cm, with a combination of rotational speed of 115, 135, and 154 rpm. In the test, the electrical power requirements, and the performance of aeration, i.e.: water covering area, bursts length, and bursts wide were measured. The test results showed that the use of electric power could be reduced about 2-5 watts using the paddle wheel aerator with movable paddles, at operating depth of 4 cm at all rotational speeds tested. But at 6 cm operating depth, the use of the movable paddles type aerator could not reduce the need for electrical power. The resulting aeration performance of of the movable paddles aerator was relatively similar with that of the fixed blade aerator.
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Judul: Budidaya dan Pengolahan Kopi di Perkebunan Jollong PT perkebunan XVIII Kabupaten Pati, Jawa Tengah
Abstrak: Kopi tergolong minuman sedap-sedapan yang relatip mahal di samping coklat dan teh. Hampir seluruh penduduk Indonesia telah mengenal kopi, bahkan banyak orang yang tak bisa melepaskan kebiasaan minum kopi dari hidupnya. Begitu pentingnya komoditi kopi, sehingga negara-negara produsen membentuk Organisasi Persetujuan Kopi Internasional. Lembaga ini mengatur jatah ekspor masing-masing negara anggota. Namun ada juga negara produsen kopi yang tidak menjadi anggota organisasi ini. Brasilia masih menduduki posisi teratas bahan minuman terpopuler di dunia ini. Sampai saat ini dalam menghasilkan Disusul oleh Columbia, Ivory Coast (Pantai Gading) dan Angola. Indonesia yang juga menjadi anggota negara-negara pengekspor kopi, menempati anak tangga ke sepuluh selama bertahun-tahun (Pattiasina, 1983). Peranan kopi Indonesia di pasaran Internasional masih relatip kecil dan belum nyata, meskipun Indonesia ter- golong sebagai produsen dan eksportir kedua kopi Robusta setelah Ivory Coast (AEKI, 1984). Hal ini disebabkan karena Indonesia tidak memiliki perwakilan tetap di dalam forum ICO, sebagaimana yang dimiliki oleh Brasilia, Columbia maupun Pantai Gading.
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