Judul: Management of Sugarcane (Saccharum officinarum  L.) in the Operational Area of Madukismo Sugar Mill, PT Madubaru Yogyakarta,  with Specific Focus on March Assessment Accuracy and Production Realization
Abstrak: Tebu (Saccharum officinarum L.) termasuk komoditas tanaman yang banyak dibutuhkan dalam rumah tangga dan industri, sehingga produksi diperlukan untuk memenuhi permintaan. Tuntutan produksi yang tinggi mendorong perusahaan tebu agar teliti dalam memperkirakan total produksi mendatang. Metode untuk memperkirakan total produksi panen adalah taksasi produksi. Taksasi digunakan sebagai acuan dalam perencanaan panen agar dapat menghitung kebutuhan tenaga kerja, peralatan panen, serta kapasitas giling. Magang ini bertujuan mempelajari pengelolaan tebu secara aspek budidaya dan aspek manajerial. Aspek khusus yang dipelajari adalah ketepatan taksasi tebu pada bulan Maret dengan realisasi produksi di kebun tebu PG Madukismo, PT Madubaru, Yogyakarta di wilayah Sleman dan Bantul. Analisis data menggunakan uji homogenitas t-student dengan taraf kesalahan 5%. Nilai taksasi produksi di PG Madukismo secara umum belum mencapai ketepatan yang baik karena perbedaan taksasi-produksi di luar batas yang ditentukan yakni 95%. Nilai ketepatan taksasi tahun 2023 pada Rayon Bantul yakni 100,25% dan Rayon Sleman 106,46%. Mayoritas kebun di Rayon Bantul dan Rayon Sleman belum memenuhi standar ketepatan taksasi-produksi PG Madukismo meskipun secara rata-rata selisihnya tidak lebih dari 5%. Upaya yang dapat dilakukan untuk meningkatkan ketepatan taksasi-produksi yakni dengan memperhitungkan kemungkinan adanya kehilangan hasil tebu yang disebabkan oleh beberapa faktor seperti panen dengan tunggul tinggi, serangan hama dan penyakit, kerusakan akibat cuaca buruk, serta ketelitian pengamatan dalam perhitungan taksasi., Sugarcane (Saccharum officinarum L.) is a commodity plant highly demanded in households and industries, making its production essential to meet the demand. The high demand for production drives sugarcane companies to be meticulous in estimating future total output. One method used for this is production appraisal. Appraisal is used as a reference in harvest planning to calculate labor requirements, harvest equipment, and milling capacity. This internship aims to study sugarcane management from both cultivation and managerial perspectives. The specific aspect under study is the accuracy of sugarcane appraisal in March compared to the realized production in the sugarcane plantations of PG Madukismo, PT Madubaru, Yogyakarta, in the Sleman and Bantul regions. Data analysis employs the t-student homogeneity test with a 5% error margin. The overall production appraisal values at PG Madukismo have not yet reached a good accuracy level due to differences between appraisal and production beyond the specified threshold of 95%. The accuracy values for the year 2023 in the Bantul Region were 100,25%, and in the Sleman Region were 106,46%. The majority of plantations in the Bantul and Sleman Regions have not met the accuracy standard of PG Madukismo's appraisal-production, although the average difference is not more than 5%. Efforts to improve the accuracy of appraisal-production include considering the possibility of sugarcane yield losses caused by factors such as harvest with tall stakes, pest and disease attacks, damage due to adverse weather conditions, and the precision of observation in appraisal calculations.
Keyword: harvest, losses, planning, region, standard

Judul: Management of Sugarcane (Saccharum officinarum L.) in Working Area of Madukismo Sugar Factory, Yogyakarta with Main Aspect of Productivity and Yield of Various Seed Sources
Abstrak: Produksi gula nasional belum cukup untuk memenuhi kebutuhan, sehingga kekurangannya harus dipenuhi melalui impor. Salah satu kegiatan budidaya tebu yang berpengaruh terhadap hasil gula adalah pada penyediaan dan penggunaan benih. Kegiatan magang bertujuan menganalisa perbedaan produktivitas dan rendemen tebu dari beberapa sumber benih di wilayah kerja PG Madukismo, Yogyakarta. Data primer diambil dengan melakukan pengamatan berupa taksasi produksi, pengukuran brix, dan wawancara petani. Hasil menunjukkan bahwa tidak terdapat perbedaan nyata. Produktivitas dari kebun yang benihnya berasal dari PG, petani penangkar, petani non penangkar, dan sumber tidak diketahui berturut-turut adalah 75,73 ton ha-1, 66,88 ton ha-1, 63,29 ton ha-1, dan 68,94 ton ha-1. Untuk rendemen diperoleh keempat sumber benih tersebut berturut-turut senilai 5,19 %, 6,21 %, 6,16 %, dan 5,77 %. Kedua komponen tersebut kemudian berpengaruh kepada estimasi nilai hablur yang didapatkan. Nilai hablurnya berurutan setinggi 3,93 ton ha-1, 4,15 ton ha-1, 3,90 ton ha-1, dan 3,98 ton ha-1., National sugar production not enough yet to fulfilled the needs, so that the supply shortage have to fulfilled through import. One of the activities in sugarcane cultivation that influences sugar result are depends on the provision and usement of it seeds. The internship program aims to analyzing the differences of productivity and yield of sugarcane from several seed sources in the working area of Madukismo Sugar Factory, Yogyakarta. Primary data are taken in the form of production estimates, brix measurements, and farmers interview. The result showing, there are no real difference. Productivity from plantations which seed sources come from sugar factory, breeder farmers, non-breeder farmers, and unknown seeds source with the values in order are 75,73 tonnes ha-1, 66,88 tonnes ha-1, 63,29 tonnes ha-1, and 68,94 tonnes ha-1. Regarding yield obtained of those four seed sources in order with values of 5,19 %, 6,21 %, 6,16 %, and 5,77 %. Those two components then affect the sugar crystal obtained. Crystal values in order as high as 3,93 tonnes ha-1, 4,15 tonnes ha-1, 3,90 tonnes ha-1, and 3,98 tonnes ha-1.
Keyword: brix, productivity, seed, sugar cane, yield

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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