Judul: Manajemen Panen dan Efisiensi Pengangkutan Tandan Kelapa Sawit di Kebun Adolina, PT. Perkebunan Nusantara IV Sumatera Utara.
Abstrak: Kegiatan magang dilaksanakan di Kebun Adolina, PT. Perkebunan Nusantara IV Sumatera Utara pada tanggal 5 Februari 2018 sampai 30 Juni 2018. Pemanenan perlu dilakukan dengan baik untuk mendapatkan rendemen minyak yang tinggi dengan kadar asam lemak bebas yang rendah. Secara umum pengamatan terhadap manajemen panen terdiri organisasi panen, perencanaan panen, pelaksanaan panen, pengawasan dan evaluasi panen. Secara khusus efisensi pengangkutan diamati dengan membandingkan teknis dan waktu muat buah pada hanca. Hasil pengamatan terkait manajemen panen seperti rotasi panen, estimasi dan realisasi dari angka kerapatan panen, jumlah tenaga kerja, kriteria matang panen mengalami deviasi dari standar prosedur operasional (SPO) perusahaan. Hal ini dilakukan untuk mencapai target produksi bulanan saat kerapatan buah menurun akibat pencurian. Di kebun tidak ditemukan adanya losses berupa buah matang tidak dipanen setelah ada perubahan sistem hanca. Selain itu terdapat perbedaan tingkat kepatuhan pemanen pada tanaman yang menggunakan sistem tanam standar dan big hole. Hasil pengamatan terkait efisiensi pengangkutan menunjukkan adanya perbedaan teknis dan waktu yang nyata antara cara pengangkutan menggunakan jembatan atau tidak.
Keyword: hanca, hole, pengangkutan, penyesuaian

Judul: Manajemen Panen Kelapa Sawit (Elaeis guineensis Jacq.) di Kebun Adolina, PT Perkebunan Nusantara IV, Serdang Bedagai, Sumatera Utara.
Abstrak: Internship aims to improve the ability and comprehension in the management of oil palm plantation. Internship implemented in Adolina Estate, PTPN IV. In the implementation of internship, harvest management in the oil palm harvesting was accentuated to observed and studied. Observation in harvest management consists of harvest rotation, harvest density, assessed daily production, harvester requirements, criteria of ripe harvest, harvester capacity, quality fruit, and transporting the fruit to oil palm mill. Data from observation were analyzed quantitatively using the average, percentage, and standard deviation (descriptive statistics) as well as the t-student test (comparison). The results from analyzed showed that harvest management of oil palm in Adolina Estate need to be improved. It is due to harvester capacity is lower of standard company and the high production percentage of fruits have not quality. The low capacity of harvesters affect the calculation of harvester requirements and disruption of harvest rotation. Harvest rotation is disturbed affect the high production percentage of fruits have not quality. Adolina Estate has implemented assessed harvest density quite accurately to the realization of the harvest density. The accuracy of the assessed harvest density to realization of harvest density affect the accuracy of the assessed daily production as well as calculation of harvester requirements and transport harvest.
Keyword: harvester capacity, harvest management, oil palm, harvester

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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