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Agustinus Ribal
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Mathematics

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Persamaan Difusi Dua Dimensi yang Tidak Steady dengan Metode Elemen Hingga Agustinus Ribal; Jeffry Kusuma
Jurnal Matematika, Statistika dan Komputasi Vol. 5 No. 1: July 2008
Publisher : Department of Mathematics, Hasanuddin University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (381.144 KB) | DOI: 10.20956/jmsk.v5i1.3339

Abstract

Dalam tulisan ini akan dibahas suatu solusi numerik persamaan difusi dua dimensi yang tidak steady dengan metode elemen hingga. Pertama-tama variasional statemen akan diturunkan dari persamaan pembangun, selanjutnya akan ditentukan persamaan elemen hingga Galerkin berdasarkan variasional statemennya. Dalam menentukan elemen matriksnya, akan digunakan 4-titik master elemen. Juga dalam perhitungan integral elemen akan digunakan kuadratur Gauss dengan 3 titik. Metode Crank–Nicolson digunakan untuk diskritisasi waktu.
Solusi Numerik Persamaan Differensial Biasa Dengan Menggunakan Metode Predictor – Corrector Agustinus Ribal; Khaeruddin Khaeruddin
Jurnal Matematika, Statistika dan Komputasi Vol. 5 No. 2: January 2009
Publisher : Department of Mathematics, Hasanuddin University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (468.764 KB) | DOI: 10.20956/jmsk.v5i2.3348

Abstract

Dalam tulisan ini akan diperkenalkan suatu solusi numerik dari persamaan differensial biasa order pertama dengan menggunakan metode predictor-corrector. Pertama-tama formula predictor akan ditentukan, kemudian menurunkan predictor formula untuk Adam-Bashforth beserta dengan corrector formulanya dimana corrector formula akan digunakan untuk mengoreksi nilai yang telah diprediksi. Selanjutnya, perulangan corrector akan dilakukan. Metode Runge Kutta orde keempat akan digunakan sebagai nilai awal dari metode predictor.
Optimization of CV.Amanda Makassar Production Planning in the Time of Covid-19 Using Multiple Goal Linear Program Model Astri Aksan; Aidawayati Rangkuti; Agustinus Ribal
Jurnal Matematika, Statistika dan Komputasi Vol. 17 No. 2 (2021): JANUARY 2021
Publisher : Department of Mathematics, Hasanuddin University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20956/jmsk.v17i2.11793

Abstract

A research has been conducted on the use of multiple-goal linear program model to solve multi goals by taking the case of optimization of production planning at CV. Amanda Makassar during the Covid-19 period. In this research, four goals were formulated, that were (i) the fulfillment of the number of market demand, (ii) maximizing income, (iii) minimizing production costs, and (iv) maximizing working hours. Then for the optimal solution using LINGO 18 software. Based on the research results, the optimal production plan during the Covid-19 period resulted from the two different models for original brownies products where the results of the dual-purpose linear program model without target priority produced 16.118 original brownies and 32.400 packages from the dual-purpose linear program model with priority target with weight. For cream cheese brownies, there are 3.000 packages, 18.000 packages of sarikaya pandan brownies, 3.600 packs of choco marble brownies, pink marble brownies, tiramishu marble brownies, roasted brownies, and 1.800 packs of cappuccino marble brownies. Chocolate bananas bolen, pineapple molen, and chocolate ganache in 840 packages. Then for 15.000 packs of blueberry brownies, 960 packs of strawberry brownies, 360 packs of dry brownies, 2.400 banana cheese brownies, 300 packs of cheese bananas bolen, 600 packs of peanut butter, and 9.000 packs of pandan cake for a month. The maximum revenue obtained by the company with a multiple-purpose linear program model without target priority is Rp.628.602.000.- and the minimum production cost that the company must pay is Rp.495,048,300,-. Then for the multiple-purpose linear program model with target priority accompanied by a weight of Rp.4.299.480.000.- and the minimum production cost is Rp.3.394.366.000. The result shows that optimization using a multiple goal linear program model with goal priority provide optimal production which results in greater profit compared to the process (optimization) carried out by the company so far, which is only based on the number of demand.
Metode MacCormack untuk menyelesaikan model transpor sedimen permukaan dasar satu dimensi Irfan Said; Agustinus Ribal; Khaeruddin Khaeruddin
Jurnal Matematika, Statistika dan Komputasi Vol. 19 No. 2 (2023): JANUARY 2023
Publisher : Department of Mathematics, Hasanuddin University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20956/j.v19i2.24182

Abstract

In this work, we investigate the numerical solution of one-dimensional bed-load sediment transport model using two steps finite difference method which so-called MacCormack method. Bed-load sediment transport model is composed by the shallow water equation and Exner equation. The Meyer-Peter and Muller (MPM) formula and Wu formula will be used to determine the Grass factor of the bed-load sediment transport. These governing equations will be discretized into predictor and corrector steps of the MacCormack method. The numerical results of the MacCormack method will be validated with an analytical solution of the bed-load sediment transport model. In addition, the MacCormack solution will also be compared with experimental solutions and another numerical method solutions that have existed previously. The numerical results based on MacCormack method give excellent results in which the numerical and the analytical results are hardly differentiated with RMSE of around 00042  or 4,2 .
Co-Authors Aidawayati Rangkuti Astri Aksan Irfan Said Jeffry Kusuma Khaeruddin Khaeruddin