Articles
<![CDATA[Optimization of fuzzy entropy on solar panel’s motor ]]>
<![CDATA[MUHAMMAD IKHWAN]]>;
<![CDATA[MARWAN RAMLI]]>;
<![CDATA[MARDLIJAH MARDLIJAH]]>
<![CDATA[ Jurnal Natural Volume 22 Number 1, February 2022 ]]>
Publisher : <![CDATA[Universitas Syiah Kuala ]]>
Show Abstract
|
Download Original
|
Original Source
|
Check in Google Scholar
|
Full PDF (1290.897 KB)
|
DOI: 10.24815/jn.v22i1.23187
<![CDATA[Renewable energy has been in great demand by the public, even some countries have set regulations for substitution and transition from fossil energy to renewable energy. This study aims to modify the fuzzy control system with a metaheuristic method, namely fuzzy entropy. The entropy value of the fuzzy set in the previous stage becomes the basis for calculating the foot of uncertainty in the new fuzzy set. This process makes the entropy method parallel to other optimization methods that have been carried out on fuzzy control systems. The results obtained indicate that the modified fuzzy control system successfully controls the angle and angular velocity of the solar panel. The error value shown is very small and the time to reach stability is below 5 s. This is a rapid development of several previous studies. The modified system has no overshoot and steady state error below 1%. Based on these results, entropy research can be developed again by changing the fuzzy set to a more complex form.]]>
<![CDATA[Penerapan Metode Kalman Filter dalam Estimasi Harga Saham Menggunakan Model ARCH-GARCH ]]>
<![CDATA[Lusi Nur Rahmawati]]>;
<![CDATA[Mardlijah Mardlijah]]>;
<![CDATA[Amirul Hakam]]>
<![CDATA[ Jurnal Sains dan Seni ITS Vol 12, No 1 (2023) ]]>
Publisher : <![CDATA[Lembaga Penelitian dan Pengabdian Kepada Masyarakat (LPPM), ITS ]]>
Show Abstract
|
Download Original
|
Original Source
|
Check in Google Scholar
|
DOI: 10.12962/j23373520.v12i1.96240
<![CDATA[Saham merupakan produk pasar modal yang menjadi salah satu instrumen investasi. Banyak investor yang memilih saham sebagai instrumen investasi dikarenakan saham memberikan keuntungan yang menarik. Metode estimasi merupakan metode yang tepat bagi para investor untuk memprediksi harga saham sehingga dapat membantu mengoptimalkan keuntungannya. Penelitian ini bertujuan untuk menentukan model terbaik dari data harga saham menggunakan model ARCH-GARCH dan mendapatkan hasil estimasi harga saham menggunakan metode Kalman Filter dengan model ARCH-GARCH untuk periode selanjutnya. Adapun data harga saham yang digunakan yaitu data harga saham PT. Telkom Indonesia Tbk yang diambil dari website resmi Yahoo Finance. Data yang diambil adalah data harga saham saat penutupan (close) periode 29 Februari 2020 sampai 31 Agustus 2021. Pada data harga saham digunakan model ARIMA (Autoregressive Integrated Moving Average) dan terdeteksi terdapat unsur heteroskedastisitas, sehingga digunakan model time series ARCH-GARCH (Autoregressive Conditional Heteroskedasticity Generalized Autoregressive Conditional Heteroskedasticity). Didapatkan model terbaik yaitu GARCH (1,1) dengan model ARIMA (2,1,3). Pada penerapan metode Kalman Filter didapatkan hasil estimasi harga saham lebih akurat yaitu mendekati data aktual yang ditandai dengan nilai MAPE (Mean Absolute Percentage Error) pada GARCH-Kalman Filter lebih kecil dibandingkan nilai MAPE pada model GARCH (1,1).]]>
<![CDATA[Optimization of fuzzy entropy on solar panel’s motor ]]>
<![CDATA[MUHAMMAD IKHWAN]]>;
<![CDATA[MARWAN RAMLI]]>;
<![CDATA[MARDLIJAH MARDLIJAH]]>
<![CDATA[ Jurnal Natural Volume 22 Number 1, February 2022 ]]>
Publisher : <![CDATA[Universitas Syiah Kuala ]]>
Show Abstract
|
Download Original
|
Original Source
|
Check in Google Scholar
|
DOI: 10.24815/jn.v22i1.23187
<![CDATA[Renewable energy has been in great demand by the public, even some countries have set regulations for substitution and transition from fossil energy to renewable energy. This study aims to modify the fuzzy control system with a metaheuristic method, namely fuzzy entropy. The entropy value of the fuzzy set in the previous stage becomes the basis for calculating the foot of uncertainty in the new fuzzy set. This process makes the entropy method parallel to other optimization methods that have been carried out on fuzzy control systems. The results obtained indicate that the modified fuzzy control system successfully controls the angle and angular velocity of the solar panel. The error value shown is very small and the time to reach stability is below 5 s. This is a rapid development of several previous studies. The modified system has no overshoot and steady state error below 1%. Based on these results, entropy research can be developed again by changing the fuzzy set to a more complex form.]]>
<![CDATA[Mathematical Modelling of Inventory Costs in Supply Chains with Horizontal Cooperation ]]>
<![CDATA[Zahara, Chasna]]>;
<![CDATA[Mardlijah, Mardlijah]]>
<![CDATA[ International Journal of Global Operations Research Vol. 5 No. 2 (2024): International Journal of Global Operations Research (IJGOR)m May 2024 ]]>
Publisher : <![CDATA[iora ]]>
Show Abstract
|
Download Original
|
Original Source
|
Check in Google Scholar
|
DOI: 10.47194/ijgor.v5i1.283
<![CDATA[Efficiency in the supply chain has become very important for companies in the era of increasingly fierce business competition. This has encouraged some companies to start implementing the concept of collaboration between companies or commonly called horizontal cooperation. Horizontal cooperation is important because companies need to work together to manage complex supply chains. To manage production in a collaborative supply chain requires designing a cost-effective model. The design of this model is expected to optimise inventory costs to achieve common goals in horizontal cooperation. This model is a form of linear programme consisting of objective function and constraint function. The objective function is to minimise the inventory cost in a four-tier supply chain with horizontal cooperation on post-production final storage at the production level only. The model was tested with 3 suppliers, 3 materials, 3 factories, 4 products, 3 distributors, and 3 consumers. The model with horizontal cooperation resulted in a total inventory cost of 1,349,830. This amount is 8% lower than the total inventory cost without horizontal cooperation. Thus, horizontal cooperation in the supply chain drastically reduces inventory costs throughout the supply chain.]]>
<![CDATA[Optimizing Algal Bloom Through Bioenzyme and Harvesting Control for Bioenergy Purposes in Eutrophic Water Bodies ]]>
<![CDATA[Akbar, Fadilah]]>;
<![CDATA[Mardlijah, Mardlijah]]>
<![CDATA[ Jambura Journal of Biomathematics (JJBM) Volume 5, Issue 2: December 2024 ]]>
Publisher : <![CDATA[Department of Mathematics, Universitas Negeri Gorontalo ]]>
Show Abstract
|
Download Original
|
Original Source
|
Check in Google Scholar
|
DOI: 10.37905/jjbm.v5i2.26938
<![CDATA[This article discusses the optimization of algae growth for bioenergy purposes in eutrophic water bodies through bioenzyme control and harvesting. The study explores innovative approaches to manage algae growth in such water bodies. A mathematical model based on dynamical systems, specifically the NASC (Nutrients, Algae, Detritus, and Dissolved Oxygen) algae growth model, was used for the analysis. The results indicate that the system used is unstable, given the needs of algae growth over time. To optimize algae growth, this study proposes controlling the bioenzyme (u1) feeding to decompose detritus into nutrients and harvesting algae using (u2). The Pontryagin Maximum Principle (PMP) method was used to obtain optimization with control parameters u1=0.093 and u2=0.32. The results show that the optimal time to harvest algae is every 84 days or 2.8 months, with an estimated harvestable amount of 16.3667 . This discovery enhances our understanding of controlling algae growth in the context of renewable energy and reinforces the mathematical approach to managing eutrophic aquatic ecosystems.]]>
<![CDATA[LQR and Fuzzy-PID Control Design on Double Inverted Pendulum ]]>
<![CDATA[Damayanti, Erlyana Trie]]>;
<![CDATA[Mardlijah, Mardlijah]]>;
<![CDATA[Rohman Wijaya, Ridho Nur]]>
<![CDATA[ CAUCHY: Jurnal Matematika Murni dan Aplikasi Vol 9, No 1 (2024): CAUCHY: JURNAL MATEMATIKA MURNI DAN APLIKASI ]]>
Publisher : <![CDATA[Mathematics Department, Universitas Islam Negeri Maulana Malik Ibrahim Malang ]]>
Show Abstract
|
Download Original
|
Original Source
|
Check in Google Scholar
|
DOI: 10.18860/ca.v9i1.22070
<![CDATA[Double inverted pendulum is a non-linear and unstable system. Double inverted pendulum can be stabilized in the upright position by providing control to the system. In this research we compare two types of controllers namely Linear Quadratic Regulator (LQR) and Fuzzy-PID. The objective is to determine the control strategy that provides better performance on the position of the cart and pendulum angle. We modelled the system which is then linearized and given control. From the simulation results, it is proven that LQR and Fuzzy-PID controllers have been successfully designed to stabilize the double inverted pendulum. However, when given a disturbance in the form of noise step, the LQR controller has not been able to achieve the desired reference for up to 20 seconds. In another hand, the Fuzzy-PID controller is able to achieve the desired reference after 8 seconds. Therefore, it can be concluded that the Fuzzy-PID controller when applied to the Double Inverted pendulum system has better performance than the LQR controller.]]>
<![CDATA[Optimal Feeding Strategy on Microalgae Growth in Fed-Batch Bioreactor Model ]]>
<![CDATA[Nailul Izzati]]>;
<![CDATA[Mardlijah Mardlijah]]>
<![CDATA[ (IJCSAM) International Journal of Computing Science and Applied Mathematics Vol. 1 No. 1 (2015) ]]>
Publisher : <![CDATA[LPPM Institut Teknologi Sepuluh Nopember ]]>
Show Abstract
|
Download Original
|
Original Source
|
Check in Google Scholar
<![CDATA[Some countries in the world turn to alternative energy source to fulfill their necessity of fuel. One of the alternative fuels is biodiesel. Raw material of biodiesel can be produced by microalgae cultivation in fed-batch bioreactor. To improve the productivity of microalgae cultivation, we need to determine the optimal control of microalgae growth. This paper discusses mathematical model of microalgae growth in fed-batch bioreactor, and solves the optimal feeding strategy problem by using Pontryagin Minimum Principle. Then we compare the controlled microalgae growth model with the uncontrolled one. Numerical simulation with DOTcvpSB shows that the controlled microalgae growth model yields more harvest and less cost function than the uncontrolled one.]]>
<![CDATA[The Effect of Collector in Solar Still for Water Productivity Using Runge-Kutta Method ]]>
<![CDATA[Mardlijah Mardlijah]]>;
<![CDATA[Achmad Fatoni]]>;
<![CDATA[Lukman Hanafi]]>
<![CDATA[ (IJCSAM) International Journal of Computing Science and Applied Mathematics Vol. 1 No. 1 (2015) ]]>
Publisher : <![CDATA[LPPM Institut Teknologi Sepuluh Nopember ]]>
Show Abstract
|
Download Original
|
Original Source
|
Check in Google Scholar
<![CDATA[Solar still is a renewable energy technology. It can reduce crisis of clean and healthy water in some countries. Solar still produces clean and healthy water using the sunlight, but the result of distillate water is not so much. Hence the need for modifications with the addition of collector can increase the yield of distillate water. Mathematical model of solar still with collector is in the form of system of differential equations. It can be solved numerically using Runge-Kutta method. From the simulation, we conclude that the collector increases the amount of distillate water in the solar still.]]>
<![CDATA[Implementation of Fuzzy-PID Controller on Quadcopter Movement ]]>
<![CDATA[Dinda Anisa’ Maulina]]>;
<![CDATA[Mardlijah Mardlijah]]>
<![CDATA[ (IJCSAM) International Journal of Computing Science and Applied Mathematics Vol. 10 No. 2 (2024) ]]>
Publisher : <![CDATA[LPPM Institut Teknologi Sepuluh Nopember ]]>
Show Abstract
|
Download Original
|
Original Source
|
Check in Google Scholar
|
DOI: 10.12962/j24775401.ijcsam.v10i2.4578
<![CDATA[A UAV is an unmanned aerial vehicle, one of which is a Quadcopter. A Quadcopter has a simple structure and small size. Therefore, high maneuverability allows the Quadcopter to take off, fly, and land in narrow areas. The speed of the four motor-driven propellers affects the quadcopter’s motion. The problem that often occurs in Quadcopters lies in the lifting force. Where the speed of the four motors must be the same so that the lift force can make the Quadcopter reach the desired height. The study aims to control the angular velocity and speed of the Quadcopter on the z-axis. The Quadcopter motion system model is a non-linear system because environmental disturbances give the system very high uncertainty. The system is given a control design in the form of Fuzzy-PID (Fuzzy Proportional Integral Derivative) with the desired set point or speed is 1. Simulation is carried out by comparing the system without disturbance and with disturbance to see how the speed of the Fuzzy-PID stabilizes the system. The simulation results show that even though the system is disturbed, the fuzzy-PID control can guide it toward the desired set point.]]>
<![CDATA[Design of Monkeypox Virus Spread Control in Humans Using Pontryagin Minimum Principle ]]>
<![CDATA[Lukman Hanafi]]>;
<![CDATA[Mardlijah Mardlijah]]>;
<![CDATA[Daryono Budi Utomo]]>;
<![CDATA[Suhud Wahyudi]]>;
<![CDATA[Alya Nur Sha-brina]]>
<![CDATA[ (IJCSAM) International Journal of Computing Science and Applied Mathematics Vol. 10 No. 2 (2024) ]]>
Publisher : <![CDATA[LPPM Institut Teknologi Sepuluh Nopember ]]>
Show Abstract
|
Download Original
|
Original Source
|
Check in Google Scholar
|
DOI: 10.12962/j24775401.ijcsam.v10i2.4582
<![CDATA[Monkeypox is a contagious disease caused by a virus. In Africa, monkeypox results in death in 1 out of 10 infected individuals. The Food and Drug Administration in the United States recommends vaccination as a preventive measure against monkeypox virus. If infected, the World Health Organization (WHO) advises quarantine to prevent further transmission to others. This research develops a mathematical model known as SIR (Susceptible-Infected-Recovered) for the spread of monkeypox virus, incorporating vaccination and quarantine as control measures. The SIR model utilized is based on an existing model and follows the conditions of monkeypox spread in Nigeria, represented as a system of nonlinear differential equations. Optimal control is determined using the Pontryagin Minimum Principle and simulated using the fourth-order forward-backward sweep Runge-Kutta method to assess the level of monkeypox infection before and after implementing control measures. Based on the simulation results, it is concluded that the application of control measures can reduce the population of infected monkeys by 70% and infected humans by 59%.]]>
