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: Performance and Economics Test of Rice Combine Harvester in Innovation Village, Subang, West Java
Abstrak: Penanganan padi siap panen merupakan salah satu kunci untuk meningkatkan perolehan hasil dari kemungkinan pengurangan nilai susut. Proses pemanenan padi di Indonesia banyak dilakukan secara manual dengan cara dipotong dengan menggunakan sabit dan perontokan dengan cara digebot yang berdampak pada susut yang tinggi. Penggunaan alat dalam memanen padi seperti combine harvester sudah banyak ditemukan karena memiliki susut yang relatif kecil, namun kalah bersaing karena stigma akan biaya operasional yang terlalu mahal yang akan berdampak pada pendapatan petani. Penelitian ini bertujuan untuk menganalisis aspek kinerja dan ekonomi dari penggunaan combine harvester sebagai alat bantu proses pemanenan padi; membandingkan hasil analisis pemanenan padi menggunakan combine harvester dengan cara manual; serta menganalisis kelayakan usaha mesin combine harvester di Kampung Inovasi Subang, Desa Kiarasari, Kecamatan Compreng, Kabupaten Subang. Penelitian dilakukan dengan mengamati beberapa variabel dalam pemanenan secara manual dan pemanenan dengan menggunakan combine harvester. Variabel yang diamati berupa variabel kinerja berupa kapasitas lapang efektif (KLE) dan kapasitas lapang teoritis (KLT) pemanenan secara mekanis (ha/jam), KLE dan KLT pemanenan secara manual, efisiensi lapang pemanenan (ELP) (%), susut panen (%), dan variabel ekonomi berupa biaya pokok pemanenan (Rp/ha). KLE pemotongan dengan sabit memiliki nilai rata-rata sebesar 0,018 ha/jam/orang dan efisiensi pemotongan sebesar 77% sedangkan KLE menggunakan combine harvester sebesar 0,5047 ha/jam dan efisiensi pemotongannya sebesar 82,28%. Susut hasil pemotongan padi menggunakan sabit sebesar 7,50% dengan susut perontokannya sebesar 0,086% sehingga total susut sebesar 7,59%, sementara susut total pemanenan menggunakan combine harvester sebesar 0,067%. Biaya total pemanenan dengan metode manual (sabit + power thresher) sebesar Rp 3.531.577,00 /ha, sedangkan biaya total yang dengan combine harvester sebesar Rp 1.857.143,00 /ha., Handling ready-to-harvest rice is one of the keys to increasing yield gain from possible reduction in value of losses. The process of harvesting rice in Indonesia is mostly done manually by cut using a sickle and threshing with digebot which has an impact on high shrinkage. The use of tools in harvesting rice such as a combine harvester has been widely found because it has a relatively small shrinkage, but it is less competitive because of the stigma of operational costs that are too expensive which will have an impact on farmers' income. This study aims to analyse the performance and economic aspects of using a combine harvester as a tool for rice harvesting; compare the results of rice harvesting analysis using a combine harvester with the manual method; and analyse the business feasibility of combine harvester machines in Subang Kampung Inovasi, Kiarasari Village, Compreng Subdistrict, Subang Regency. The research was conducted by observing several variables in manual harvesting and harvesting using a combine harvester. The variables observed were performance variables in the form of effective field capacity (KLE) and theoretical field capacity (KLT) of mechanical harvesting (ha/h), KLE and KLT of manual harvesting, harvesting field efficiency (ELP) (%), harvest shrinkage (%), and economic variables in the form of cost of harvesting (Rp/ha). The ELP of cutting with sickle has an average value of 0,018 ha/hour/person and cutting efficiency of 77% while the ELP using combine harvester is 0,5047 ha/hour and the cutting efficiency is 82,28%. The shrinkage of rice
Keyword: biaya operasional, combine harvester, panen padi, produktivitas, susut, operational cost, productivity, rice harvesting, shrinkage

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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