Judul: Palm Oil Plantation Weed Control Management (Elaeis guineensis Jacq.) PT Supra Matra Abadi, Aek Nabara, North Sumatra
Abstrak: Pengendalian gulma merupakan kegitan penting di perkebunan kelapa sawit karena keberadaan gulma meberikan pengaruh negatif bagi perkebunan kelapa sawit akibat adanya kompetisi antara gulma dengan tanaman kelapa sawit. Kegiatan magang di kebun Aek Nabara PT Supra Matra Abadi bertujuan meningkatkan kemampuan kerja secara teknis dan manajerial, serta mempelajari manajemen pengendalian gulma perkebunan. Kegiatan magang dilaksanakan pada bulan Januari hingga Mei 2021. Metode yang digunakan adalah metode langsung (data primer) dan tidak langsung (data sekunder). Pengamatan analisis vegetasi menunjukkan bahwa gulma Asystasia gangetica merupakan gulma dominan di areal TBM dan TM muda dengan nilai SDR sebesar 38,69% dan 30,20%. Gulma Centotheca lappacea merupakan gulma dominan di areal TM tua dengan nilai SDR sebesar 43,57%. Estimasi biaya pengendalian gulma ha-1 tahun-1 mencapai Rp. 1.113.000,00 untuk biaya herbisida dan Rp. 294.291,00 untuk biaya HK. Prestasi tenaga kerja di Kebun Aek Nabara adalah 0,16 ha HK-1 . Persentase tingkat penggunaan APD di Aek Nabara cukup rendah yaitu 75,6% hal ini diduga karena kacamata safety googles tidak digunakan sama sekali dalam proses penyemprotan. Kata kunci: Analisis vegetasi, APD, CDA, estimasi biaya, prestasi kerja., Weed control is an important activity in oil palm plantations because the presence of weeds has a negative influence on oil palm plantations due to competition between weeds and palm oil plants. Internship activities at Aek Nabara Plantation of PT Supra Matra Abadi aim to improve technical and managerial work capabilities, as well as study the management of plantation weed control. Internship activities are held from January to May 2021. The methods used are direct (primary data) and indirect (secondary data) methods. Observations of vegetation analysis showed that asystasia gangetica weeds are the dominant weeds in young TBM and TM areas with SDR values of 38.69% and 30.20%. Centotheca lappacea weed is the dominant weed in the old TM area with an SDR value of 43.57%. Estimation cost of weed control ha-1 year-1 reaches Rp. 1.113.000,00 for herbicide costs and Rp. 294.291,00 for HK fees. Labor performance in Aek Nabara Plantation is 0.16 ha HK-1. The percentage of APD use rate in Aek Nabara is quite low, which is 75.6% this is suspected because googles safety glasses are not used at all in the spraying process.
Keyword: APD, CDA, cost estimation, vegetation analysis, work performance

Judul: Pengendalian Gulma Kelapa Sawit (Elaeis guineensis Jacq) di Kebun Seed Garden Buatan, PT Inti Indosawit Subur, Riau.
Abstrak: Gulma di lahan kelapa sawit yang tidak dikendalikan menurunkan hasil panen sehingga perlu pengendalian gulma yang efektif dan efisien. Magang memiliki tujuan umum meningkatkan kemampuan teknis dan manajerial dalam kegiatan budidaya kelapa sawit serta tujuan khusus menambah pemahaman dalam pengendalian gulma di Kebun Seed Garden Buatan, PT Inti Indosawit Subur, Riau. Magang dilaksanakan di KSB, PT Inti Indosawit Subur, Pangkalan Kerinci, Pelalawan, Riau pada bulan Januari sampai Mei 2023. Metode yang digunakan metode langsung (data primer) dan tidak langsung (data sekunder). Pengamatan data primer gulma dengan NJD menunjukkan gulma yang dominan di areal piringan yaitu Eleusine indica menunjukkan SDR tertinggi yaitu 45,28% pada TBM, 30,92% pada TM muda, dan 27,14% pada TM tua. Centotheca lappacea nilai SDR tertinggi pada TM muda 35,42% dan TM dewasa 55,7%. Cyperus kyllingia nilai SDR tertinggi gulma ini pada TBM yaitu 46%, TM muda yaitu 50,05%, dan TM dewasa 27,29%. Asystasia gangetica nilai SDR tertinggi di TM dewasa senilai 17,03%. Pengendalian gulma di KSB dilaksanakan dengan cara manual, kultur teknis, kimiawi, dan mekanis. Penting dilakukan pengawasan mengenai kondisi alat semprot agar penggunaan biaya pengendalian lebih efisien. Persentase tingkat penggunaan APD sebesar 58% dan tergolong rendah., Uncontrolled weeds in oil palm fields reduce yields so effective and efficient weed control is needed. The internship has a general objective to improve technical and managerial skills in oil palm cultivation activities and a specific objective to increase understanding in weed control in the Artificial Seed Garden, PT Inti Indosawit Subur, Riau. The internship was carried out at KSB, PT Inti Indosawit Subur, Pangkalan Kerinci, Pelalawan, Riau from January to May 2023. The methods used were direct (primary data) and indirect (secondary data). Observation of primary weed data with NJD showed that the dominant weed in the disk area, namely Eleusine indica, showed the highest SDR of 45,28% in TBM, 30,92% in young TM, and 27,14% in old TM. Centotheca lappacea had the highest SDR value in young TM at 35,42% and mature TM at 55,7%. Cyperus kyllingia had the highest SDR value in TBM at 46%, young TM at 50,05%, and mature TM at 27,29%. Asystasia gangetica had the highest SDR value in mature TM at 17,03%. Weed control in KSB is carried out by manual, technical culture, chemical, and mechanical means. It is important to monitor the condition of the spray equipment so that the use of control costs is more efficient. The percentage of PPE usage rate is 58% and is classified as low.
Keyword: gulma, teknik pengendalian, biaya, APD, weeds, control techniques, cost, PPE

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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