Judul: Analisis efektivitas pengendalian gulma secara mekanis, kimia dan kombinasi pada kebun tebu rakyat di Cimahpar, Bogor
Abstrak: This research aims to study any weed control methods on sugarcane plantation, was conducted on sugarcane plantation in Cimahpar, North Bogor – Bogor from May to August 2010. The experimental used ten levels of weed control treatments and two replications. The treatments were Ko = without weed control, M = mechanical, MM = mechanical – mechanical, MMM = mechanical –mechanical - mechanical MK = mechanical – chemical, MMK = mechanical – mechanical – chemical, MKM = mechanical – chemical – mechanical, K = chemical, KM = chemical – mechanical and KMM = chemical – mechanical – mechanical. Controlling method chemically used two varies herbicide, gliphosate and paraquat, while controlling method mechanically was conducted by using walking type cultivator. Glyphosate herbicide has been used on sugarcane area dominated by Imperata cylindrica and paraquat herbicide has been used on sugarcane area dominated by grass or Paspalum conjugatum. The result showed that the treatment of MMK could suppress the growth of weeds, especially Imperata cylindrica is the best in the percentage of weeds by 0.75% and 1.505 cm high weeds on domination Imperata cylindrica areas. MKM treatment showed suppression of growth of weeds, especially Paspalum conjugatum of the best weed in the percentage of weeds 9% and 4.39 cm high weeds on sugarcane Paspalum conjugatum areas. Paraquat herbicide usage caused poisoning symptoms in sugarcane with exist of color change on sugarcane stem, further symptoms was not causing death.
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Judul: Weed Control Management of Tea (Cammellia sinensis (L.) Kuntze) Plantation at PT Perkebunan Nusantara XII, Malang, East Java
Abstrak: Gulma merupakan tumbuhan yang kehadirannya dapat mengganggu pertumbuhan tanaman, sebab gulma dapat menurunkan hasil produksi tanaman. Pengendalian gulmaperlu dilakukan agar kerugian yang diakibatkan oleh gulma bisa diatasi. Kegiatan magang bertujuan memahami dan mempelajari pengelolaan pengendalian gulma serta menganalisis aspek pengendalian gulma yang dilakukan di kebun. Hasil pengamatan menunjukan pengendalian gulma di Afdeling Wonosari dilakukan secara manual dan kimiawi. Pengendalian gulma manual dilakukan untuk mengendalikan gulma diatas bidang petik, gulma yang tingginya >30 cm, serta gulma berkayu. Pengendalian kimiawi dilakukan dengan alat knapsack sprayer dan herbisida yang digunakan berupa herbisida sistemikdengan bahan aktif Isopropilamina Glyphosat. Pengendalian gulma secara kimiawi lebih efektif dan efisien dari sisi tenaga kerja, biaya, serta hasil luasan yang dikerjakan. Kalibrasi semprot dilakukan sebelum dilakukan penyemprotan untuk mengetahui volume semprot yang diperlukan agar penyemprotan dapat dilakukan secara efektif. Keefektifan penyemprotan herbisida dipengaruhi oleh waktu pengaplikasian, waktu turunnya hujan,serta kemampuan penyemprot., Weeds are plants that can interfere with plant growth, because weed can reduce crop production. Weed control needs to be done so that the losses caused by weeds can be overcome. The internship activity aims to under standard study weed control management and analyze aspects of weed control carried out in the garden. Observations showed that weed control in Afdeling Wonosari was carried out manually and chemically. Manual weed control was carried out to control weeds above the picking field, weeds >30 cm high, and woody weeds. Chemical control is carried out by means of a knapsack sprayer and the herbicide used is a systemic herbicide with the active ingredient Isopropylamine Glyphosate. Chemical weed control is more effective and efficient in terms of labor, costs,and the results of the area worked. Spray calibration is carried out before spraying to determine the volume of spray required so that spraying can be carried out effectively. The effectiveness of herbicide spraying is influenced by the time of application, the time of rain, and the ability of the sprayer.
Keyword: Isopropilamina glyphosat, Systemic herbiside, Community coefficient, Spray calibration

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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