Judul: Panen dan Pascapanen pada Umbi Bibit dan Umbi Konsumsi Kentang (Solanum tuberosum L.) di Hikmah Farm, Pangalengan, Bandung, Jawa Barat.
Abstrak: General purpose of the internship was to study the potato cultivation and to train technical and managerial skills in problem analyzing on field, especially on the purpose harvesting and postharvest handling aspect. The specific purpose was to observe the effect of harvesting time quality of the tuber, the influence of harvesting method efficiency of harvesting labour and losses of product, the influence of the height of fall out tuber on the damage of tuber, and to observe the percent loss that of product in the field and the storage. The results of specific aspect showed that longer harvesting time harder the tuber skin up to 100 %. Plants that harvested too young will produce small tubers percentage higher than large tubers. Acquisition of tuber fresh weight will be low if the harvesting time is less than 90 days and more than 100 days after planting. Method harvest 1 (digging with gala, drying, sorting and grading, rafting step 1, transport step 2 ) is the highest to get the crop quality. Method harvest 2 (digging with a hoe, drying, sorting and grading, rafting step 1, transport step 2) is the best way to get the efficiency of harvesting labour. Damage of tuber for seed is higher than tuber for consumption. The highest tuber damage occurs when the tuber is dropped at a height of 2.5 m. Percentage tuber losses in storage was higher than losses in the field. The range yield loss in the field between 1 % up to 3 % and yield loss in the storage between 9 % up to 52 %.
Keyword: yield loss, post-harvest, potato (Solanum tuberosum L.), method harvest, harvest

Judul: Penggunaan Berbagai Ukuran dan Periode Simpan Umbi Kentang Bibit (Solanum tuberosum L.) di Hikmah Farm, Pangalengan, Bandung, Jawa Barat
Abstrak: The general objective of this internship is to broadening the knowledge and improve the working experience in both technical and managerial. The spesific objective of internship is to study the effect of various size and storage periods of potato tuber seeds to the potatoes productivity. The result of first spesific aspect shows that the use of large seed potato tubers will produce more stems per clumps which will produce more small tuber size . The result of a second aspect experiment shows that the storage periode tuber seeds has a significants effect to the amount of small (S) tuber per plants and to the weight of small (S) tubers per row. The tuber with long storage periods tend to grow shoot faster but easier to attack by pest and disease. Long storage periods resulting more non-productive branch, low –productive, and die faster
Keyword: potatoes, potato tuber size, potato tubers storage periode, seeds potato

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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