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All Journal JOURNAL OF EARTH ENERGY ENGINEERING BAREKENG: Jurnal Ilmu Matematika dan Terapan JPMB Parahita Limits: Journal of Mathematics and Its Applications
Tasmi Tasmi, Tasmi
Computer Science, Faculty Of Science And Computers, Pertamina University
Humanities Computer Science & IT Control & Systems Engineering Earth & Planetary Sciences Economics, Econometrics & Finance Energy Engineering Materials Science & Nanotechnology Mathematics Mechanical Engineering Medicine & Pharmacology Nursing Physics Transportation

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A Mathematical Model of Intermittent Gas Lift in Elevation-Production Operation with Line-Pack and Line-Drafting Phenomena in a Gas Line Silvya Dewi Rahmawati; Tasmi Tasmi; Pudjo Sukarno; Agus Yodi Gunawan; Edy Soewono; Septoratno Siregar; Edward L. Tobing
Journal of Earth Energy Engineering Vol. 9 No. 2 (2020): OCTOBER
Publisher : Universitas Islam Riau (UIR) Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25299/jeee.2020.5264

Abstract

This paper discusses a transient model of the intermittent gas lift technique in an oil well. The model is developed in the gas line, in the tubing-casing annulus, and the tubing. The line-pack and line-drafting phenomena in the gas line are considered in the model. A numerical approach will be used to solve the mathematical model that represents fluid flow during intermittent gas lift injection. The dynamics of important variables in the intermittent gas lift are investigated and analyzed to determine the best production strategy for intermittent gas lift. The variables are film thickness and velocity, slug height and velocity, and gas height and velocity. The relationships between surface injection control parameters (gas injection pressure and gas injection rate) and the velocity and height of film, gas, and liquid are shown in one cycle of the gas lift intermittent process. The higher the gas injection pressure, the faster the gas injection velocity, and the thinner the film thickness in the tubing. In order to obtain clean tubing from film thickness, the gas injection pressure needs to be optimized, which will lead to maintaining compressor discharge pressure availability. Detailed observation of the dynamic performance inside the tubing production well will give the optimum oil production rate for oil wells under a gas lift intermittent production strategy for field application.
Be Wise With Your Waste: Penyuluhan Sampah Dan Evaluasi Usability Aplikasi Pengelolaan Sampah Untuk Siswa Sekolah Menengah Atas Di Jakarta Selatan Suharti, Suharti; Yunita, Ariana; Tasmi, Tasmi; Adharis, Azis; Mayangsari, Tirta Rona; Ratri, Paramita Jaya; Berghuis, Nila Tanyela; Muttaqin, Muttaqin; Sofiyah, Evi Siti; Fuqaha, Hafizh; Istadewi, Berliani; Afiq, Muhammad; Sakinah, Nanda; Fauziyah, Andanda Reza
Jurnal Pengabdian Masyarakat Bakti Parahita Vol. 4 No. 02 (2023): Jurnal Pengabdian Masyarakat Bakti Parahita
Publisher : Universitas Binawan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.54771/jpmbp.v4i02.1193

Abstract

Indonesia merupakan penyumbang sampah plastik terbesar ketiga di dunia pada tahun 2020, dimana DKI Jakarta merupakan salah satu kota penyumbang sampah terbesar di Indonesia. Untuk menangani sampah plastik diperlukan kerjasama dari berbagai pihak, baik dari masyarakat, akademisi, pemerintah dan organisasi. Tanpa kontribusi publik, penanganan sampah terutama sampah plastik akan sulit. Tujuan kegiatan ini adalah untuk meningkatkan kesadaran masyarakat untuk memilah dan menangani sampah, sebagai upaya untuk meningkatkan kontribusi publik. Pada kegiatan ini, salah satu aplikasi pengelolaan sampah diperkenalkan dan dilakukan evaluasi usability untuk mengetahui seberapa mudah digunakan aplikasi tersebut. Kegiatan dilakukan pada 50 siswa salah satu Sekolah Menengah Negeri Atas Negeri (SMAN) di Jakarta Selatan. Hasil dari kegiatan ini menunjukkan bahwa siswa-siswa berminat untuk menggunakan aplikasi pengelolaan sampah, tetapi masih mengalami kesulitan dalam menggunakan aplikasi pengelolaan sampah. Selain itu, sebagai tindak lanjut dari penyuluhan ini, tempat sampah untuk memisahkan sampah plastik juga diletakkan di sekolah tersebut sebagai tindak lanjut dari penyuluhan ini.
Comparative Analysis of Mathematical Models: A Case Study of Used Smartphone Price Depreciation Chandrawisesa, Muhammad Nezha Alfatah; Safitri, Annisa Rizky; Almuzakki, Muhammad Zaki; Tasmi, Tasmi
Limits: Journal of Mathematics and Its Applications Vol. 22 No. 2 (2025): Limits: Journal of Mathematics and Its Applications Volume 22 Nomor 2 Edisi Ju
Publisher : Pusat Publikasi Ilmiah LPPM Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/limits.v22i2.3469

Abstract

The price depression of the smartphone after it becomes used is one of the factors that consumers should consider when buying used smartphones. Therefore, accurate prediction of the price of used smartphones becomes a better insight into marketing strategies, and consumer purchasing decisions. The study aims to compare the performance of the Holt-Winters model damped, logistical decay, and exponential decay to predict the price depression of used smartphones. This research method uses historical data from some used smartphone prices as a basis for analysis. Comparisons between the three models were made to assess the performance of each in representing price depression behavior. Then, a statistical analysis was conducted to determine the most optimal model in predicting the price depression of used smartphones, the optimity of a model measured by the accuracy and speed of the computer performing the model execution. The accuracy measure in this study is the mean square error (MSE) value generated by a model with historical data alignment based on the ratio to the price when the smartphone has not been indicated as usable and the execution speed measure is the time it takes a computer to execute the model. The results show that the Holt-Winters damped model provides the most optimal predictive results compared to the exponential and decay models. This is demonstrated by the lower MSE average value twice as low as compared with the other two models, on the other hand, the holt-winters Damped has the weakness of requiring the longest average execution time of the three models with an average performance speed of 2.7 seconds, but the shortfall is not fatal because the predicted time period in this case is monthly so there is no urgency to advance the speed of seconds rather than accuracy.
DESIGN OPTIMIZATION OF GAS TRANSMISSION SYSTEM WITH DIFFERENTIAL EVOLUTION ALGORITHM Afdhal, Ahmad; Tasmi, Tasmi; Yunita, Ariana; Noegraha, Rangga Ganzar
BAREKENG: Jurnal Ilmu Matematika dan Terapan Vol 20 No 2 (2026): BAREKENG: Journal of Mathematics and Its Application
Publisher : PATTIMURA UNIVERSITY

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30598/barekengvol20iss2pp1089-1098

Abstract

Gas distribution through a pipeline network is a highly complex process and requires significant financial investment. This network system consists of a source, pipe, the compressor and sink (consumer). The source is the node where the producer has the gas pressure that will be distributed, the pipe is used to connect the producer and the consumer. Between the pipes there is a compressor which functions to increase the pressure. This network system was created at a significant cost, so it is necessary to search for minimal costs, but consumer demand is still met. This research discusses the search for an optimal gas network with minimum costs. This minimum cost depends on several parameters i.e. the length and diameter of pipe, also the pressure on the compressors entry and exit points. There are many optimization methods, but one of the simple and easy to implement methods is the Differential Evolution Algorithm, so this method is used to determine the optimal solution to this problem. Researchers used seven DE variants based on mutation strategies, namely DE/rand/1, DE/best/1, DE/rand/2, DE/best/2, DE/current-to-best/1, DE/current-to- rand/1, and DE/rand-to-best/1. The seven variants have never been used in gas distribution networks by previous researchers. Therefore, the seven variants were compared, and the minimum solution was determined. The results show that the DE/best/2 variant is the variant that produces the minimum total costs compared to the other variants. DE/best/2 achieved the lowest annual operating cost at USD 13.99 million.
Co-Authors Adharis, Azis Afdhal, Ahmad Afiq, Muhammad Agus Yodi Gunawan Aldri Frinaldi Almuzakki, Muhammad Zaki Ariana Yunita Berghuis, Nila Tanyela Chandrawisesa, Muhammad Nezha Alfatah Edward L. Tobing Edy Soewono Fauziyah, Andanda Reza Fuqaha, Hafizh Istadewi, Berliani Jayawarsa, A.A. Ketut Mayangsari, Tirta Rona Noegraha, Rangga Ganzar Pudjo Sukarno Ratri, Paramita Jaya Safitri, Annisa Rizky Sakinah, Nanda Septoratno Siregar Silvya Dewi Rahmawati Sofiyah, Evi Siti