Judul: Management of Sugarcane (Saccharum  officinarum L.) at Kebun Tebu Mas, Sugar Factory in Lamongan with Special  Aspect of Productivity in Each Plant Category
Abstrak: Gula merupakan salah satu komoditas terpenting nomor dua setelah beras yang kebutuhannya masih sangat tinggi di industri maupun rumah tangga. Pengelolaan tebu dilakukan untuk meningkatkan hasil produktivitas di tiap kategori tanaman. Tebu yang dikepras secara berulang dapat menyebabkan turunnya produktivitas. Tujuan magang adalah untuk membandingkan produktivitas tebu setiap kategori tanaman tahun giling 2021 dengan produktivitas tebu setiap kategori tanaman tahun giling 2020. Kegiatan magang dilaksanakan pada 25 Januari hingga 12 Mei 2021 di PG Kebun Tebu Mas, Lamongan, Jawa Timur. Hasil pengamatan menunjukan produktivitas tanaman tebu pada varietas Cening dan Bululawang menunjukan peningkatan produktivitas pada tahun giling 2021, kecuali varietas Cening ratoon cane (RC) atau tanaman keprasan (RC) III yang mengalami penurunan produktivitas. Produktivitas tertinggi pada varietas Cening terdapat pada kategori tanaman RC II, sedangkan pada varietas Bululawang pada kategori tanaman plant cane (PC) atau tanaman pertama. Analisis usaha tani menunjukan kategori tanaman RC pada kedua varietas memiliki keuntungan lebih tinggi daripada kategori tanaman PC., Sugar is one of the most important commodities after rice whose need is still very high in industry and households. Sugarcane management is carried out to increase productivity in each plant category. Sugarcane that is ratooned repeatedly can cause a decrease in productivity. The purpose of this internship is to compare the productivity of each plant category in the 2021 milled year with sugarcane productivity in each category for the 2020 milled year. The internship was held from January 25th until May 12th, 2021 at Kebun Tebu Mas’ Sugarcane, Lamongan, East Java. The results showed that the productivity of sugarcane in the Cening and Bululawang varieties showed an increase in productivity in the 2021 milling year, except for the variety of Cening’s RC III, which experienced a decrease in productivity. The highest productivity in the Cening was in the ratoon cane (RC) II plant category, while in the Bululawang was in the first plant or plant cane (PC) category. Farming analysis showed that the RC plant categories in both varieties had the highest profit compared to the PC plant category.
Keyword: gula, produktivitas, tanaman pertama, tanaman keprasan

Judul: Pengelolaan Tanaman Tebu (Saccharum officinarum L.) di Pabrik Gula Madukismo, PT. Madubaru, Yogyakarta: dengan Aspek Khusus Mempelajari Produktivitas Tiap Kategori Tanaman
Abstrak: The study of the productivity of the various categories of sugarcane held in the Madukismo Millsworking area, Madubaru Company, Yogyakarta. This activity began in February 13 to May 14, 2012. The sample is taken at Sleman and Bantul district. The method used is the direct field observation, data from the division of plant productivity, as well as interviews with farmers. The results obtained on the productivity of down land is higher than up land. Differences in land characteristics influence the productivity of sugarcane. In addition, the downland productivity tended to decrease from the plant cane (PC) to ratoon crop (RC) in each subsequent season. For up land, there is higher productivity at ratoon cane I (RC 1) increase from low productivity in the plant cane (PC) and then back on every ratoon crop the following season. To overcome the low productivity of ratoon sugarcane needed to do the loading or replanting, or ratoon intensif nurse.
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Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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