Judul: Kinerja dan Keekonomian Mesin Perontok untuk Kedelai (Studi kasus : Kecamatan Majalengka, Kabupaten Majalengka).
Abstrak: Threshing is one of the important postharvest handling of soybean, where the use of proper threshing machine would be able to reduce the quantity losses and quality losses due to mechanical damage to the threshing process. Mechanical damage arising from the motion mechanism such as motion of stripping, hammering, and impact. Motion mechanism is very dependent on the drum cylinder speed threshing used. Therefore, this study aims to assess the performance threshing machine and analyze the magnitude of losses arising from threshing activities and to analyze the economic in operational of the threshers. This research was conducted in the Sindang Kasih village, Majalengka district with raw materials of Argomulyo soybean varieties. Threshing was done by using two multipurpose threshers, namely thresher A and thresher B as a test group with two treatments that was drum cylinder speed threshing of 515-570 rpm and 580-650 rpm. Observations were done at quantity and quality losses (split seeds, damaged seeds, and dirt). Quantity losses resulting from threshing activities were used to analyze the economics and feasibility of threshers. Economic analysis was done by determining the fixed costs, variable costs, BEP, cost of product and benefits of the threshing process, where feasibility of business was done based on of NPV, IRR, net B/C and payback period . The used thresher on a drum cylinder speed of 580-650 rpm produces the highest quantity and quality losses compared with 515-570 rpm of the both threshers operated. The highest quantity losses on a thresher A was 3.33 %, split seeds was 2.9 % and damaged seeds was 2.57 %, while the quantity losses on a thresher B was 0.72 %, 0.89 % of split seeds and damage seeds was 1.43 % on the thresher operated with drum cylinder speed of 580-650 rpm. The high losses produced at drum cylinder speed 580-650 rpm, therefore the operation of thresher should be done at 515-570 rpm of drum cylinder speed. From the economic analysis, the two threshing machine, was reached a feasibleoperational level with cost of product was Rp. 327/kg-Rp. 369/kg and BEP 15.7-19.2 ha equivalent to 23 562-28 852 kg seeds/year . This effort deserves to be developed with a range of NPV Rp. 1 997 037-Rp. 6523 947, 19.63-32.42 % IRR and a net B/C 1.11-1.43 in the applicable equipment rent wasRp. 400 / kg .
Keyword: Economic, soybean, threshing, quantity losses, quality losses

Judul: Uji beban kerja alat perontok padi tipe pedal berbasis sepeda (bicycle type mobile thresher)
Abstrak: Indonesian is an agriculture country and rice is the most important crop to be grown because it is the stople ford of more than 95% of population. High demand of rice is one big reason that we need to increase productivity, decrease yield loss and build suistainable farming system.Manual threshing method is one of the main factors of high loss in harvesting activity of paddy cultivation. Appropiate and affordable threshing machine might be a solution to decrease the loss problem. There are various of mobile thresher have been produced and circulating in farm society.One of them is Obelt thresher which was developed in 2008 by Niko Daniar Atmaja student of Agriculture Engineering Department IPB. The main objective of the research is to find out the work productivity labour workload and energy cost to operate O-belt thresher, and to compare with manual thressing. As the result, the energy cost of O-belt thresher is 616.809 kcal/kg.h, compare to that manual threesing is 738.812 kcal/kg.h. O-belt threshing has produces 35.7 kg/hour and manual threesing compare to that the produces 19.2 kg/hour. Manhour of O-belt thresher to thressing one hectare yield of paddy is 140.5 hour/h, compare to that the manual thressing is 260.42 hour/h. According to the results, O-belt thresher is more effective than manual threesing.
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Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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