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Riri Syafitri Lubis

Universitas Islam Negeri Sumatera Utara, Medan, Indonesia

Author-ID : 3325332

Religion Agriculture, Biological Sciences & Forestry Humanities Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Decision Sciences, Operations Research & Management Earth & Planetary Sciences Economics, Econometrics & Finance Education Electrical & Electronics Engineering Energy Engineering Environmental Science Health Professions Industrial & Manufacturing Engineering Languange, Linguistic, Communication & Media Law, Crime, Criminology & Criminal Justice Library & Information Science Materials Science & Nanotechnology Mathematics Mechanical Engineering Medicine & Pharmacology Physics Public Health Social Sciences Transportation Other

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POPULATION PROJECTION AND FACTOR ANALYSIS AFFECTING POPULATION GROWTH IN THE CITY MEDAN USING NON LINEAR TRENDS POLYNOMIC METHOD Pertiwi, Fina Nur; Lubis, Riri Syafitri; Widyasari, Rina
Journal of Mathematics and Scientific Computing With Applications Vol. 2 No. 1 (2021)
Publisher : Pena Cendekia Insani

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.53806/jmscowa.v2i1.47

Non-linear trend is a measure of trend that has a model with quadratic equations, cubic and so on. The purpose of this research is to determine the population projection in Medan using a non-linear trend of the polynomial method (parabolic trend / quadratic trend) and to determine the factors that influence population growth in the city of Medan. From the results of data processing using the non-linear trend of the polynomial method, it is obtained that the projected number of population in 2029 will be 2645501 people, with The total male population is 1314713 and the female population is 1330788. When compared with the population in previous years, it can be seen that until 2029 the population in Medan will increase. Based on the research results from the factor analysis, it is known that the factors that are formed from the factor analysis process can be concluded that all the factors formed affect the population growth rate of Medan. The factors formed are birth (fertility), death (mortality) and migration.

IMPLEMENTATION OF THE GENERALIZED SPACE TIME AUTOREGRESSIVE (GSTAR) MODEL IN THE CASE OF THE SPREAD OF CORONAVIRUS IN THE DISTRICT CITY OF NORTH SUMATRA Nasution, Alfina Febriani; Lubis, Riri Syafitri; Widyasari, Rina
ZERO: Jurnal Sains, Matematika dan Terapan Vol 6, No 2 (2022): Zero: Jurnal Sains Matematika dan Terapan
Publisher : UIN Sumatera Utara

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30829/zero.v6i2.14785

Corona Virus Disease 2019 (COVID-19) is a new virus that can be transmitted and the worst impact is death. Covid-19 first appeared in Wuhan, China and eventually spread throughout the world, one of which was North Sumatra Province. The spread of Covid-19 cases was quite rapid, until finally the World Health Organization (WHO) declared the Covid-19 case a pandemic. Based on the conditions that occurred, this final project discusses the prediction of positive cases of Covid-19 in five locations in North Sumatra using the Generalized Space Time Autoregressive (GSTAR) model. Considering that Covid-19 spreads very easily, it does not only depend on time but also the proximity between locations, so the GSTAR model is quite good to use in predicting it, assuming the parameters between locations are heterogeneous. The estimation used is OLS with inverse distance weight. This study aims to determine the best GSTAR model and forecast positive cases of Covid-19 at five locations in North Sumatra. The results show that the best GSTAR model in this study is -OLS with an inverse weight of distance with forecasting results for the next 10 days in May 2022.

Solusi Numerik Model Verhulst Pada Estimasi Hasil Panen Melalui Perkembangan Produksi Padi dan Beras dengan Metode Milne-Simpson Arjuna, Dimas Bagus; Lubis, Riri Syafitri
Journal of Information System Research (JOSH) Vol 5 No 2 (2024): Januari 2024
Publisher : Forum Kerjasama Pendidikan Tinggi (FKPT)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.47065/josh.v5i2.4857

The aim of this research is to develop a numerical solution using the Verhulst model to estimate paddy and rice production in North Sumatra. The Milne-Simpson method is used in this research to provide an efficient numerical approach in solving the model, with the aim of increasing the accuracy and effectiveness of estimating rice plant growth and rice production in the North Sumatra region through a systematic and computational approach. In this research, the Milne-Simpson method is used to estimate paddy and rice production results in the following year. The results show that the estimated rice production in North Sumatra Province is 2,086,590.76 tons in 2023 and 2,098,149 tons in 2024. Meanwhile, the estimated rice production in North Sumatra Province is 1,198,678.38 tons in 2023 and 1,207,384 tons in 2024. The results of this research also show that every year rice production increases by an average of 13,430 and rice production increases by an average of 8,254. Therefore, it can be seen that the estimated paddy and rice production in North Sumatra Province for 2023-2024 has increased.

Probabilistic Model of Back Order Policy on Dodol Pulut Raw Material Inventory Control With Linear Programming Br Siahaan, Erika Handayani; Riri Syafitri Lubis
KUBIK Vol 10 No 1 (2025): KUBIK: Jurnal Publikasi Ilmiah Matematika
Publisher : Department of Mathematics, Faculty of Science and Technology, UIN Sunan Gunung Djati Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15575/kubik.v10i1.49121

The high production costs of Dodol Pulut Raya further emphasize the importance of implementing a systematic, measurable, and effective inventory control strategy to maintain profitability, operational efficiency, and long-term business stability. This study applies the Probabilistic Back Order Policy Model combined with the Simplex Linear Programming method to determine the most optimal raw material management policy, taking into account demand uncertainty, supply variability, and the risk of stock shortages that could disrupt production smoothness. This approach comprehensively integrates precise safety stock calculations to minimize stockouts, reduce production delays, and ensure raw material availability so that customer needs can be consistently, timely, and sustainably met. The analysis results show that the implementation of this model can significantly reduce annual production costs from IDR 509,941,040 to IDR 338,719,300, resulting in cost efficiency of IDR 171,221,740 per year. This finding demonstrates the model's effectiveness in minimizing total inventory costs while enhancing competitiveness and operational sustainability. Additionally, this study provides a practical framework for small and medium-sized enterprises facing fluctuating demand, balancing service levels, safety stock, and overall cost optimization.

PENERAPAN MODEL ARIMA UNTUK PERAMALAN JUMLAH ORANG YANG MELAKUKAN PEMBAYARAN PROGRAM JAMINAN HARI TUA PADA BPJS KETENAGAKERJAAN CABANG TANJUNG MORAWA Lubis, Riri Syafitri; Fadhliyah, Annisa; Ananda, Lyra; Pohan, Siti Rolizah
Community Development Journal : Jurnal Pengabdian Masyarakat Vol. 5 No. 1 (2024): Volume 5 No 1 Tahun 2024
Publisher : Universitas Pahlawan Tuanku Tambusai

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31004/cdj.v5i1.26017

Penelitian ini mengevaluasi penerapan model ARIMA dalam meramalkan jumlah individu yang melakukan pembayaran Program Jaminan Hari Tua (JHT) di BPJS Ketenagakerjaan Cabang Tanjung Morawa. Menggunakan data pembayaran periode Januari 2019 hingga Desember 2023, penelitian bertujuan memahami pola dan tren pembayaran, sehingga dapat memberi prakiraan akurat untuk mendukung keputusan manajemen dalam merencanakan dan mengalokasikan sumber daya. Analisis melibatkan transformasi Box-Cox dan uji stasioner pada rangkaian waktu untuk menentukan orde model ARIMA yang paling sesuai. Hasil menunjukkan bahwa model ARIMA (1,0,1) menjadi model terbaik dengan nilai MAPE sebesar 21,1%, menunjukkan tingkat kesalahan peramalan yang dapat diterima. Dengan demikian, penelitian ini dapat dijadikan sebagai acuan dalam meramalkan pembayaran JHT di masa mendatang.

A Integrasi IOT Dalam Efisiensi Energi Listrik Rumah Tangga Berbasis Smart Grid Menggunakan Metode Fuzzy Sugeno Lubis, Riri Syafitri; Serdano, Akbar
Sepren Vol 7 No 01 (2025): Edisi November 2025
Publisher : Prodi Pendidikan Matematika FKIP Universitas HKBP Nommensen

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36655/sepren.v7i01.2023

Penggunaan energi listrik rumah tangga pada umumnya hanya dapat dipantau melalui meteran listrik rumah tangga, bukan melalui arus listrik yang keluar dari alat rumah tangga yang digunakan. Pada dasarnya penggunaan energi listrik rumah tangga berdasarkan berapa jumlah alat rumah tangga yang digunakan dan dalam keadaan hidup. Pemanfaatan teknologi juga belum secara maksimal dilakukan seperti penggunaan perangkat IoT yang dijual pasaran atau penerapan langka-langkah penghematan energi listrik mulai dari mematikan alat rumah tangga yang tidak terpakai maupun penggunan sensor otomatis memutuskan arus listrik jika tidak terpakai. Dengan memanfaatkan teknologi Internet of Things (IoT) dapat membantu memantau dan mengontrol arus keluar listrik melalui perangkat handphone. Selain itu, dapat mengurangi konsumsi listrik rumah tangga dengan mematikan / mematikan secara otomatis saat arus keluarnya berlebihan / tidak sedang digunakan. Penggunaan IoT dalam rumah tangga belum dilakukan secara maksimal, konsep smart grid yang dapat mengontrol penghematan serta memantau pemakaian energi listrik rumah tangga menjadikan solusi terbaik ditambah dengan metode fuzzy yang digunakan akan lebih jauh mengefisiensikan enerfi listrik rumah tangga.

PENERAPAN METODE MONTE CARLO DALAM MEMPREDIKSI JUMLAH PENGANGGURAN DI SUMATERA UTARA dewi, mutia hatina; Lubis, Riri Syafitri; Cipta, Hendra
JOURNAL OF SCIENCE AND SOCIAL RESEARCH Vol 8, No 4 (2025): November 2025
Publisher : Smart Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.54314/jssr.v8i4.4642

Abstract: Unemployment is still a problem that often occurs in every region, including in every area in North Sumatra. Unemployment rates can inevitably lead to an increase in poverty. And this can continuously trigger other losses such as rampant robbery, theft, fraud and even crimes that will harm the general public. The purpose of this study, among others, is to predict the number of unemployed in each district/city of North Sumatra from 2021 to 2025 using the Monte Carlo method and find out whether this method can be used to predict population such as unemployment. The advantage of this method lies in strong numerical calculations in simulating data by producing accurate values and the results of predicting the number of unemployed in 2021, 2023 and 2024 have decreased with the number of unemployed each year ranging from 426383, 426383 and 399403 people. Meanwhile, for 2022 and 2025 it will be an increase of 43260 and 41605 people.Keyword: Predicting, Number of Unemployed, Monte CarloAbstrak: Pengangguran masih menjadi permasalahan yang kerap terjadi di setiap daerah termasuk di setiap daerah yang ada di Sumatera Utara. Tingkat pengangguran yang tidak terelakan dapat memicu terjadinya peningkatan kemiskinan, kriminalitas. seperti maraknya perampokan, pencurian, penipuan bahkan kejahatan yang akan merugikan khalayak ramai maupun kesenjangan sosial dan dampak negatif lainnya. Tujuan dari penelitian ini antara lain untuk memprediksi jumlah pengangguran di setiap daerah Sumatera Utara perkabupaten/ kota tahun 2021 sampai dengan 2025 dengan menggunakan metode Monte Carlo serta mengetahui apakah metode tersebut dapat digunakan dalam memprediksi kependudukan seperti pengangguran. Keunggulan metode ini terletak pada perhitungan numerik yang kuat dalam mensimulasikan data dengan menghasilkan nilai yang akurat dan hasil dari memprediksi jumlah pengangguran di tahun 2021, 2023 dan 2024 mengalami penurunan dengan jumlah pengangguran disetiap tahunnya berkisar 426383, 426383 dan 399403 jiwa. Sedangkan untuk tahun 2022 dan 2025 mengalami kenaikan sebesar 43260 dan 41605 jiwa.Kata kunci: Prediksi, Jumlah Pengangguran, Monte Carlo

Sistem Pendukung Keputusan Analisa Kinerja Instruktur (Honorer) Balai Besar Pelatihan Vokasi Dan Produktivitas (BBPVP) Medan Dengan Metode Weighted Product (WP) Utami, Destia Nada; Latersia, Egya Dora; Tri Amisri, Nurul Hasanah; Lubis, Riri Syafitri
Jurnal Pengabdian Masyarakat Vol. 4 No. 2 (2025): Desember 2025
Publisher : Unity Academy

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.70340/japamas.v4i2.269

The performance evaluation of honorary instructors at BBPVP Medan is often subjective and lacks a measurable assessment system. This activity aims to design a decision support system to objectively evaluate instructor performance using the Weighted Product (WP) method. The evaluation criteria include attendance (40%), work discipline (35%), and teamwork (25%). Data were collected through observation, interviews, and documentation involving ten honorary instructors. The WP calculation results show that the instructor named Darmanto Koemardy achieved the highest score (0.189) and is recommended for contract extension. The application of the WP method improves the objectivity and efficiency of performance evaluations for instructors at BBPVP Medan.

MARKETING GAMES AND SENSITIVITY ANALYSIS FOR ANY NUMBER OF COMPANIES Amir, Almira; Simanjuntak, Ruth Mayasari; Suzana, Yenny; Lubis, Riri Syafitri; Syarah, Fatmah; Fajriana, Fajriana; Zahedi, Zahedi
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/barekengvol20iss2pp0927-0940

In the business world, advertising plays a crucial role in shaping market dynamics. This study analyzes advertising competition among companies by calculating the optimal profits for two to four competitors and postulating a general formula for a larger number of companies. Sensitivity analysis is employed to observe how changes in advertising parameters affect profits. The simulation results indicate that in the case of four companies, the optimal spending (Xopt) ranges from 137246 to 191288, while the optimal profit (Popt) ranges from 38693.1 to 92702. The sensitivity analysis shows that companies with higher advertising effectiveness achieve greater profits, whereas those with lower effectiveness tend to experience reductions in both allocation and profit. With the aid of Maple and Excel, this research extends previous advertising competition models by providing a comprehensive framework for optimizing advertising budgets in oligopolistic markets.

Optimizing the use of sewing materials to maximize production output Rakhmawati, Fibri; Rifki, Mhd Ikhsan; Husein, Ismail; Cipta, Hendra; Lubis, Riri Syafitri; Sari, Rina Filia
Abdimas Indonesian Journal Vol. 5 No. 2 (2025)
Publisher : Civiliza Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.59525/aij.v5i2.1043

This Community Service Program aims to optimize the use of sewing materials to maximize production output at Rumah Jahit Nila through the application of a linear programming model in the allocation and use of sewing materials in planning and maximizing production output. The implementation methods include mapping processes and data requirements and formulating a linear programming model relevant to the scale of Nila Sewing House MSMEs, as well as training and live demonstrations using QM as software to determine optimization solutions. The evaluation was conducted on 15 participants using a 1–4 Likert scale instrument with four assessment indicators, namely, training content, presenter's subject-matter expertise, event facilities, and benefits of the program. Descriptive analysis showed an overall average of 3.43 on a scale of 4, with a percentage level of 85.8%, which is in the Very Good category. In order, the indicator achievements are Presenter’s Subject-Matter Expertise = 3.53 (88.33%), Benefits of the Program = 3.47 ( 86.67%), Training Content = 3.40 (85.00%), and Event Facilities = 3.33 (83.33%). These results confirm that the competence of the speakers and the relevance of the benefits are the main strengths, while the content and facilities of the activities are areas for priority improvement. This program has successfully improved participants' technical capacity in modeling and implementing linear program-based raw material optimization, while also providing a foundation for operational implementation to reduce waste and increase throughput.

Co-Authors Ahmad Sugarda Ainun Palihah Almira Amir Ananda, Lyra Anggi Pranata Annisa, Nur Alvi Arjuna, Dimas Bagus Aslam, Fazri Aulia Turrizqiya Auliya Ramadhani, Dhea Batu, Annisa Rajaq Lumban Bella Syahrani Nasution Blaster, Irena Br Siahaan, Erika Handayani Cynthia, Mayang Modelina Dara Nurul Hasnah Dedy Juliandri Panjaitan dewi, mutia hatina Dian Darmawan Didik Santoso Didik Santoso Dinda Renata Cecilia Dwi Haprida Ningsih Elma Dwi Ariana Aprilia Zam Elpita Sari Hasibuan Evi Borliana Siregar Fachrur Rozi Fadhliyah, Annisa Fadilatus Sahraini Siregar Fadillah, Yanna Rezki Fajriana, Fajriana Farwansyah, Mhd Rio Fatmawati, Ayu Isnaini Fernando, Anjas Fikri Husin Batubara Fuja Nauli Pasaribu Giawa, Freddy Gishela Agra Moukia Gurusinga, Ditha Aulia Harleni, Harleni Hasibuan, Hani Maulida Hazizah, Salsabillah Hendra Cipta Heni Pujiastuti Ilham Salim Siregar Ilham Syaputra Indah Kholila Indah, Windi Rezeki Ir Zulkarnain, Ayu Najmita Binti Irena Blaster Ismail Husein, Ismail Kartika , Dinda Khairun Nikmah Kurahman, Panca Taufik Latersia, Egya Dora Lisa Setia Ningsih M Agung Pradana Manurung, Silvi Khairiyah Maudya Nur Azura Mhd Ikhsan Rifki Mohammad Badri Muhamar Chaniago, Febri Muhammad Arfie Munawar Muhammad Farhan Mingka Muhammad Vikry Rezky Rambe Muliawan, Hari Nabilla, Widi Ihdina Nadhila, Nurul Nasution, Alfina Febriani Nasution, Dafa Al Qifti Nasution, Fakhrur Rozi Nasution, Fakhrur Rozi Nasution, Hamidah . Neliwati Neliwati Nenna Irsa Syahputri Nina Amanda Nova Audry Utami Nurmadani Nurmawati Nurmawati Nurmawati Nurul Nadhila Nusantara, Badai Charamsar Oktaviana Oktaviana Palihah, Ainun Pertiwi, Fina Nur Pohan, Ahmad Syahrial Pohan, Siti Rolizah Pradana, M Agung Prasetya, Nurul Huda Pratiwi, Miftah Pulungan, Ahmad Fauzan Putri Harahap, Rahmelia Rahayu, Sri Ulfa Rahma Miyati Rahmat Darmawan, Rahmat Rakhmawati, Fibri Riani Dwi Lestari Ricka Afriani Rima Aprilia Rima Aprilia Rina Filia Sari Rina Filia Sari, Rina Filia Rina Sari Filia Rina Widyasari Ritonga, Nurhalimah Rivani Kabrina Br Surbakti Rizkina, Ayu Rizky Mulyani Ropiqoh Ropiqoh Ropiqoh, Ropiqoh Rusydi Ananda Ruth Mayasari Simanjuntak Sahraini Siregar, Fadilatus Sajaratud Dur Samsudin, Samsudin Sari, Evi Indah Serdano, Akbar Silvia Harleni Simamora, Devitasari Sintia Agustina Siregar Siregar, Evi Borliana Siregar, Fadilatus Sahraini Siregar, Tanti Jumaisyaroh Siti Jubaidah Siti Zunaida Nasution Suci Dahlya Narpila, Suci Dahlya Suci Permata Sari Suendri, Suendri Sulaiman Ananda Harahap Supiah Supiah Susanti, Komaria Susilowati, Rahmi Suzana, Yenny Syafitri, Ellysa Syahfitri, Fatharani Syahputra, Bayu Teza Syahputri, Linna Syahputri, Nenna Irsa Syarah, Fatmah Tanjung, Aida Febriana Tanti Jumaisyaroh Siregar Tri Amisri, Nurul Hasanah Tri Handayani Tri Lutfiah Wardah Turrizqiya, Aulia Utami, Destia Nada Utami, Ristika Dian Vani Hajari Wenny Marta Dolok Saribu Widyasari, Rina Widyasari, Rina Windi Rezeki Indah Wulandari Wulandari Wulandari, Mitha Yahfizham Yahfizham Yoffa Sunita Yulanda Novita Zebua Yulinda, Jeni Zahedi . Zakaria Alfikri Sirait Zam, Elma Dwi Ariana Aprilia Zam, Elma Dwi Ariana Aprilia

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