Judul: Draft force and energy reduction of soil tillage by Selfexcited Vibration method
Abstrak: Soil compaction potentially inhibits plant growth and reduces crop productivity. To loosen the compact soil, however high draft force and energy consumption are needed. The cause of which is due to soil cohesion, adhesion and friction between soil and tillage tool. It’s well known that vibratory-tillage could reduce that soil cohesion, adhesion and friction between soil and tillage tools so that the draft force and energy consumption required is reduced. In this research, soil tillage by self-excited vibration (SEV) method has been conducted. The objective of this research was to obtain vibratory-system of self-excited vibration vibratory-tillage (SEVVT) so that the vibration of the tillage tool will reduce draft force and energy consumption during tillage operation. The research was divided into three steps, i.e.: analytical study, equipment design and experiment study. In the analytical study, the vibration of SEVVT was simulated as a vibration with single degree of freedom system (SDOF) and two degrees of freedom system (TDOF). The vibration of tillage tool was exerted by natural excitation of the varying cutting force. The elasticity of the elastic spring or the inertia of the tillage tool was optimized such that the tillage tool vibrates violently around its resonant frequency. Draft force reductions about 22-47 % were observed. In the second step, the equipment was designed methodologically using VDI2221, with focus on the conceptual design. The embodiment design was then conducted to exemplify that the conceptual design was simple, easy to understand, and economically realizable. In the last step, soil tillage was conducted in a soil bin with the dimension of 1.2 m long, 0.3 m wide and 0.4 m depth. Clay loam soil was conditioned in soil bin into two layer namely hardpan and top soil. The tillage tool was connected to a fixed structure using a new model of semi-elliptical spring. The tillage speeds used were 0.158, 0.212 and 0.265 m/s. Five treatments were tested, i.e.: Non vibratory-system (NST), SDOF with rear spring orientation (RST), SDOF with front spring orientation (FST), TDOF system (TST) and low energy vibratory-system (VST). In the RST orientation, the draft force raised the elevation of the tillage tool tip, and the draft force caused the tillage tool tip elevation decrease in the FST orientation. Compared to NST, the average draft force in the FST orientation showed an increase of up to 46-96 %, whereas a draft force reduction were found in the RST and in the TST treatment. In the VST treatment, a small unbalance mass of 0.24 and 0.35 kg was rotated 530 and 1150 rpm respectively and causing tillage tool vibrate with low amplitude. Compared to NST, draft force reduction about 7.3-38.3 % and energy reduction about 4.8- 14.4% were found.
Keyword: Low energy vibratory-system, Tillage tool, Agricultural machine

Judul: Rancang Bangun dan Uji Unjuk Kerja Mekanisme Penggetar Dalam Usaha Menurunkan Draft Pengolahan Tanah Pada Bajak Chisel
Abstrak: Penelitian mengenai usaha mengurangi draft alat pengolah tanah dengan penggunaan getaran telah banyak dilakukan dan dikaji oleh beberapa peneliti. Penelitian pada skala laboratorium dan di lapangan menunjukkan adanya penurunan draft yang nyata pada saat pengolahan tanah. Namun besarnya penurunan draft pada saat pengolahan tanah berbeda-beda tergantung kepada beberapa faktor seperti, jenis alat pengolahan tanah, arah getaran, rasio kecepatan maju dengan kecepatan getar dan kondisi tanah pada saat pengolahan tanah dilakukan. Tujuan: penelitian ini adalah untuk merancang bangun dan melakukan uji unjuk kerja mekanisme penggetar dalam fungsinya sebagai sistem penggerak pada bajak chisel getar.
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Judul: Gambaran darah ikan mas Cyprinus carpio yang terinfeksi koi herpes virus
Abstrak: Iak memiliki sistem pertahanan tubuh untuk melawan berbagai macam penyakit. Pertahanan tubuh ikan terbagi 2 sistem yaitu pertahanan non-spesifik yang terdiri atas kulit, sisik, lendir dan darah dan pertahanan spesifik yaitu antibodi. Darah adalah cairan tubuh, yang berfungsi mengangkut oksigen, makanan dan hormon ke seluruh jaringan agar semua sel dapat berjalan sesuai fungsinya.
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