Judul: Analisis Pengendalian Persediaan Buah Segar dengan Pertimbangan Tingkat Kerusakan
Abstrak: Buah segar merupakan produk hasil pertanian yang bersifat perishable (mudah rusak). Tingkat kerusakan menjadi salah satu aspek penting yang harus diperhatikan dalam menerapkan pengendalian persediaan sebagai parameter penurunan mutu. Tujuan penelitian ini adalah untuk menentukan model persediaan yang dapat meminimumkan total biaya persediaan. Analisis pengendalian persediaan dilakukan pada Pisang cavendish dan Apel fuji RRC menggunakan model perishable inventory dengan pengembangan EOQ (Economic Order Quantity). Tingkat kerusakan buah mengikuti sebaran eksponensial. Nilai rata-rata tingkat kerusakan Pisang cavendish dan Apel fuji RRC berturut turut 0.0339fraksi/kg/hari dan 0.0283fraksi/kg/hari. Hasil analisis dengan model perishable inventory dapat menurunkan biaya total persediaan dengan frekuensi pemesanan dan kuantitas pemesanan yang optimum. Penghematan untuk Pisang cavendish sebesar Rp316 341/2 bulan atau Rp158 170.5/bulan yaitu sekitar 21.62% dengan frekuensi pemesanan 24 kali/2 bulan dan jumlah pemesanan sebanyak 117 kg/pemesanan. Penghematan untuk Apel fuji RRC sebesar Rp964 732.5/2 bulan atau Rp482 366.25/bulan, yaitu sekitar 47.59% dengan frekuensi pemesanan 23 kali/2 bulan dan jumlah pemesanan sebanyak 31 kg/pemesanan.
Keyword: Fruit, EOQ, Exponential, decay, inventory, Fresh fruit, Quality degradation, Inventing model, Canvendish banana, Fuji RPC Apple, Order quantity

Judul: Analisis Persediaan Bahan Baku Untuk Produksi Jus Buah Pada PT Amanah Prima Indonesia
Abstrak: There are many fresh fruits processing companies, some of which has been registered in Indonesia. In their operation, these companies need raw materials. The purpose of this study was to analyze the stock of raw materials for fruit juices production at the beverage drinks industry (case study at PT Amanah Prima Indonesia). The analysis has been conducted on the condition of stock, to determine the optimal amount and frequency of purchase of raw materials both in the form of fresh fruits and puree, and re-ordering point of the fresh fruits. The Economic Order Quantity (EOQ) method was used to determine the optimal amount of raw materials purchased. The result of the inventory analysis with the EOQ method indicated that: (1) the optimal amounts of raw materials purchased of each fresh fruits in 2009 and 2010 are 231 kg/order and 311 kg/order with the frequency of purchases is 17 and 22 times for apple, 964 kg/order and 1.227 kg/order with the frequency of purchases is 69 and 88 times for guava, 295 kg/order and 408 kg/order with the frequency of purchases is 21 and 29 times for pineapple, 633 kg/order and 565 kg/order with the frequency of purchases is 46 and 41 times for soursop, and 186 kg/order and 208 kg/order with the frequency of purchases is 13 and 15 times for strawberry, (2) the optimal production amounts of puree to meet the demand of fruit juices in 2009 and 2010 are 32 kg/production periods and 44 kg/ production periods with the frequency of productions is 109 and 147 times for apple, 128 kg/production periods and 163 kg/ production periods with the frequency of productions is 429 and 547 times for guava, 38 kg/production periods and 53 kg/production periods with the frequency of productions is 128 and 177 times for pineapple, 86 kg/production periods and 77 kg/production periods with the frequency of productions is 290 and 259 timess for soursop, and 26 kg/production periods and 30 kg/production periods with the frequency of productions is 89 and 100 times for strawberry. To avoid the shortage of raw materials, the company has to re-order when the stock of raw materials of each fresh fruits at the warehouse in 2009 and 2010 are 51 and 99 kg for apple, 991 and 1.204 kg for guava, 115 and 182 kg for pineapple, 562 and 308 kg for soursop, and 55 and 41 kg for strawberry. The result of EOQ analysis also indicated that the company could save their expenditure for raw materials of guava and soursop. The company could use this EOQ policy provided that the availability of the raw materials in the form of fresh fruit could be guaranteed and the amount of demand relatively stable.
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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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