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All Journal Jurnal Simetris Seminar Nasional Informatika (SEMNASIF) BAREKENG: Jurnal Ilmu Matematika dan Terapan JTAM (Jurnal Teori dan Aplikasi Matematika) Jambura Journal of Mathematics Jurnal Abdi Insani Jurnal Lebesgue : Jurnal Ilmiah Pendidikan Matematika, Matematika dan Statistika NUCLEUS: Jurnal Sains dan Teknologi Jurnal Pengabdian kepada Masyarakat Jurnal Pengabdian Kepada Masyarakat Duta.com : Jurnal Ilmiah Teknologi Informasi dan Komunikasi Journal of Community Service Prosiding Konferensi Nasional Penelitian Matematika dan Pembelajarannya Widya Didaktika: Jurnal Ilmiah Kependidikan Prosiding Seminar Nasional Unimus Proceeding International Conference on Mathematics and Learning Research
Nughthoh Arfawi Kurdhi, Nughthoh Arfawi
Department Of Mathematics, Faculty Of Mathematic And Natural Science, University Of Sebelas Maret, Indonesia
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COMPARATIVE ANALYSIS OF MANUFACTURER VS. RETAILER REFURBISHING MODELS: PROFITABILITY, PRODUCTION EFFICIENCY, AND STRATEGIC IMPLICATIONS Sudibyo, Nugroho Arif; Farida, Anisatul; Kurdhi, Nughthoh Arfawi
Jurnal Lebesgue : Jurnal Ilmiah Pendidikan Matematika, Matematika dan Statistika Vol. 5 No. 3 (2024): Jurnal Lebesgue : Jurnal Ilmiah Pendidikan Matematika, Matematika dan Statistik
Publisher : LPPM Universitas Bina Bangsa

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.46306/lb.v5i3.744

Abstract

This paper explores the profitability and operational efficiency of refurbishing models managed by manufacturers versus retailers, focusing on equilibrium pricing, production quantities, and profit outcomes in each scenario. It reveals that the retailer refurbishing model often leads to higher production quantities and greater profitability for manufacturers, particularly when refurbishing costs are significant or when manufacturers do not achieve notable efficiency gains through intelligent manufacturing. In contrast, the manufacturer refurbishing model may be less advantageous when these conditions are unfavorable. The findings underscore the need for manufacturers to carefully assess refurbishing costs, potential efficiency improvements, and market dynamics before selecting a refurbishing strategy. This study provides practical insights for optimizing refurbishing decisions and contributes to the broader understanding of supply chain management. Additionally, it sets the foundation for future research on how emerging technologies and market trends may influence the effectiveness of different refurbishing models.
Proporsionalitas Autokorelasi Spasial dengan Indeks Global (Indeks Moran) dan Indeks Lokal (Local Indicator of Spatial Association (LISA)) Saputro, Dewi Retno Sari; Widyaningsih, Purnami; Kurdi, Nughthoh Arfawi; Susanti, Ade
Prosiding Konferensi Nasional Penelitian Matematika dan Pembelajarannya 2018: Prosiding Konferensi Nasional Penelitian Matematika dan Pembelajarannya
Publisher : Universitas Muhammadiyah Surakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1488.855 KB)

Abstract

Autokorelasi spasial merupakan teknik dalam analisis spasial untuk mengukur kemiripan nilai atribut dalam suatu ruang (jarak, waktu dan area). Jika terdapat pola sistematik dalam nilai atribut tersebut,maka terdapat autokorelasi spasial.Adanya autokorelasi spasial mengindikasikan bahwanilai atribut pada area tertentu terkait oleh nilai atribut tersebut pada area lain yang letaknya salingberdekatan (bertetangga). Ketetanggaan tersebut diharapkan dapat mencerminkan derajatketergantungan area (spasial) yang tinggi apabila dibandingkan dengan area lain yang letaknyaterpisah jauh.Autokorelasi spasial diukur melalui dua indeks yaitu indeks global dan indeks lokal. Indeks Moran adalah indeks global tertua yang membandingkan nilai atribut area dengan nilaiatribut area lainnya. Sementara, Local Indicator of Spatial Association (LISA)adalah indeks lokal yang dipergunakan untuk mengevaluasi kecenderungan adanya pola secara lokal dengan menunjukkan beberapa bentuk dari hubungan spasial. Indeks Moran cenderung mengabaikan pola lokal hubungan spasial sehingga LISA memberikan hubungan spasial pada setiap wilayah pengamatan. Keduanya, baik indeks global maupun lokal mempunyai nilai yang proporsional yaitu indeks Moran proporsional dengan jumlah nilai LISA melalui matriks pembobotan spasial (W) dengan taxonomic levels. Dalam artikel ini dibuktikan proporsionalitas tersebut yakni nilai indeks Moran proporsional dengan jumlah nilai LISA.
Forecasting Import-Export Volume and Value using Support Vector Machines and Random Forests Istiqlala, Hamda Yauma; Kurdhi, Nughthoh Arfawi
Proceeding International Conference on Mathematics and Learning Research 2024: Proceeding International Conference on Mathematics and Learning Research
Publisher : Universitas Muhammadiyah Surakarta

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Abstract

National trade plays a crucial role in a country's economy by meeting the demand for goods and services. Imports and exports are vital components that significantly influence economic growth. This study aims to forecast and analyse the volume and value of imports and exports in the coming years, thereby helping the country to prepare for and enhance its competitiveness on the international stage. To achieve this, the study employs Support Vector Machine (SVM) and Random Forest methods, which have gained popularity for their high efficiency in handling classification and regression problems. These methods are particularly effective in producing accurate forecasts, especially when dealing with seasonal variations in data. The research also explores the potential of combining these methods for even more robust predictions. Additionally, the study considers external factors, such as global market trends and policy changes, which can influence trade dynamics. The findings of this research demonstrate the ability to predict future import and export volumes and values accurately. By comparing the error values in the form of Mean Absolute Percentage Error (MAPE), Mean Absolute Error (MAE), and Root Mean Squared Error (RMSE) from the model, it is proven that the SVM model is highly effective for export-import forecasting. Lower error values indicate higher prediction accuracy, highlighting the model's reliability in capturing complex trade dynamics. The insights from this study can be instrumental for policymakers and businesses in strategising for future trade activities, allowing them to make informed decisions that align with anticipated market shifts.
Optimized Approach to Electric Vehicle Routing Problem with Time Windows Using Grasshopper Optimization Algorithm Aksyarafah, Adifa Yasin; Kurdhi, Nughthoh Arfawi
Jambura Journal of Mathematics Vol 7, No 1: February 2025
Publisher : Department of Mathematics, Universitas Negeri Gorontalo

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37905/jjom.v7i1.30664

Abstract

The Electric Vehicle Routing Problem with Time Windows (EVRPTW) is a complex logistics issue that involves optimizing delivery routes for electric vehicles while adhering to strict time limits, managing limited battery capacity, and addressing recharging needs. In this research, we introduce an optimized method to tackle the EVRPTW using the Grasshopper Optimization Algorithm (GOA), a metaheuristic inspired by the swarming behavior of grasshoppers. We utilize the Solomon dataset, a recognized benchmark in logistics and vehicle routing, to assess the effectiveness of our proposed algorithm. Our focus is on minimizing the total distance traveled while ensuring timely deliveries and effectively managing battery logistics and recharging. Comparative analysis indicates that the GOA surpasses traditional methods in route efficiency, reducing travel distances, and enhancing logistical operations. This study highlights the potential of GOA as a valuable tool for overcoming the challenges associated with electric vehicle logistics, paving the way for more sustainable and efficient transportation systems.
GAME THEORY AND MARKOV CHAIN ANALYSIS OF THE DISPLACEMENT OF SHOPPING MALL VISITORS IN SURAKARTA CITY Rizkita, Nabiella Zahra; Sutanto, Sutanto; Kurdhi, Nughthoh Arfawi
BAREKENG: Jurnal Ilmu Matematika dan Terapan Vol 19 No 2 (2025): BAREKENG: Journal of Mathematics and Its Application
Publisher : PATTIMURA UNIVERSITY

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30598/barekengvol19iss2pp1047-1056

Abstract

The era of globalization has led to changes in social patterns and lifestyles. With these changes, shopping malls were built to fulfill the community’s needs. This study aims to analyze the displacement of visitors in three shopping malls in Surakarta City, namely Solo Paragon Mall, Solo Grand Mall, and Solo Square, using game theory and the Markov chain. Game theory is used to determine the optimal strategy of each shopping mall based on six indicators of visitor satisfaction, namely product diversity, presence of transportation modes, distance, price, facilities, and services. Saddle points are obtained by pure strategy. The calculation results with the game theory method resulted in three competitions. The first competition between Solo Paragon Mall and Solo Grand Mall obtained the optimal strategy of Solo Paragon Mall is product diversity. At the same time, Solo Grand Mall is the existence of transportation modes. The second competition between Solo Paragon Mall and Solo Square obtained the optimal strategy of Solo Paragon Mall, which is product diversity, while Solo Square's optimal strategy is service. Lastly, the third competition, Solo Grand Mall and Solo Square, obtained the optimal strategy of Solo Grand Mall is the presence of transportation modes and Solo Square is service. Markov chain is used to calculate the transition probability of visitors and steady state, which shows that Solo Paragon Mall is more desirable with a steady state probability of 0.4459, followed by Solo Square 0.3584 and Solo Grand Mall 0.1957. The results of this study can help shopping malls evaluate and improve their strategies to increase loyalty and attract new visitors.
Mengubah Limbah Kayu Menjadi Produk Bernilai Tinggi di Industri Kreatif Nughthoh Arfawi Kurdhi; Saputro, Dewi Retno Sari; Widyaningsih, Purnami; Sutanto, Sutanto; Setiyowati, Ririn; Sudibyo, Nugroho Arif
PaKMas: Jurnal Pengabdian Kepada Masyarakat Vol 4 No 2 (2024): November 2024
Publisher : Yayasan Pendidikan Penelitian Pengabdian Algero

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.54259/pakmas.v4i2.3252

Abstract

The UMKM involved in this community partnership program is engaged in the production of teak wood furniture. The issues currently faced are (1) a limited range of furniture products and (2) traditional management and marketing methods. This study aimed to implement technological induction to enhance productivity, creativity, and competitiveness within these UMKMs. The technological induction involved providing modern production tools for creating innovative products and developing an application boot program and server computer to enhance marketing efforts. A mixed-methods approach was used, combining case study observations and user-centred design principles to create technological solutions. The program's outcomes were assessed through partner training and mentoring, employing a problem-solving approach to address post-implementation challenges. The study found that introducing advanced production tools and digital marketing strategies significantly increased the variety of products, streamlined production processes, and expanded market reach, positioning the UMKMs for improved competitiveness in the national market. This research underscores the importance of integrating technology into small-scale industries for sustainable growth. Future efforts should focus on scaling these practices to other creative sectors for broader economic impact.
THE TRIPLE IDEMPOTENT GRAPH OF THE RING Z_n Kurniawan, Vika Yugi; Purboutomo, Bayu; Kurdhi, Nughthoh Arfawi
BAREKENG: Jurnal Ilmu Matematika dan Terapan Vol 19 No 3 (2025): BAREKENG: Journal of Mathematics and Its Application
Publisher : PATTIMURA UNIVERSITY

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30598/barekengvol19iss3pp2219-2228

Abstract

Let be a commutative ring, and denote the set of all idempotent elements of . The triple idempotent graph of , denoted by , is defined as an undirected simple graph whose vertex set . Two distinct vertices u and v in are adjacent if and only if there exists where and such that , and . This definition generalizes the notion of an idempotent divisor graph by involving a triple product, which allows deeper exploration of the combinatorial behavior of idempotents in rings. In this research, we investigate the properties of the triple idempotent graph of the ring of integers modulo n, denoted by . As a results, we establish that and , provided that the graph is connected. Furthermore, is Hamiltonian if n is a prime and , and Eulerian if n is a prime and .
IMPLEMENTATION OF THE BIDIRECTIONAL GATED RECURRENT UNIT ALGORITHM ON CONSUMER PRICE INDEX DATA IN INDONESIA Tanjung, Andjani Ayu Cahaya; Saputro, Dewi Retno Sari; Kurdhi, Nughthoh Arfawi
BAREKENG: Jurnal Ilmu Matematika dan Terapan Vol 18 No 1 (2024): BAREKENG: Journal of Mathematics and Its Application
Publisher : PATTIMURA UNIVERSITY

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30598/barekengvol18iss1pp0095-0104

Abstract

The Consumer Price Index (CPI) is the main index in measuring the inflation rate. Changes in the CPI from time to time reflect inflation and deflation, namely the higher the CPI value, the higher the inflation rate. This study aims to apply Birectional Gated Recurrent Unit (BiGRU) model to the CPI data in Indonesia. BiGRU comprises two GRU layers so it captures sequences that are ignored by the GRU. The research data is in the form of CPI data in Indonesia from January 2006 to December 2022 sourced from the website of the Central Bureau of Statistics totaling 204 data. The data is divided into training data and testing data. Training data was taken from January 2006 to July 2019 as many as 163 data. Data testing was taken from August 2019 to December 2022 as many as 41 data. Before the data is processed, a sliding window process is carried out by dividing the data into segments to reduce the error value. The window size value used is 10. In the sliding window process, the number of segments is 194 data segments. Based on the experiment results, it was concluded that the application of BiGRU to the CPI data was carried out in an experiment with 20 BiGRU architectures. BiGRU architecture was obtained which produced the lowest MAPE value, namely an architecture with two BiGRU layers having 256 neurons and 400 units, and one dense layer. In addition, the epochs used are 200 epochs, the ReLU activation function, and Adam optimization. The experimental results of the BiGRU architecture obtained a MAPE value of 0.24% which indicates that the architectural performance is very good.
CONSTRUCT THE TRIPLE ZERO GRAPH OF RING Z_n USING PYTHON Wulandari, Putri; Kurniawan, Vika Yugi; Kurdhi, Nughthoh Arfawi
BAREKENG: Jurnal Ilmu Matematika dan Terapan Vol 18 No 1 (2024): BAREKENG: Journal of Mathematics and Its Application
Publisher : PATTIMURA UNIVERSITY

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30598/barekengvol18iss1pp0507-0516

Abstract

Let be a commutative ring with nonzero identity and there exists such that , , , denotes the set of all triple zero elements of . The triple zero graph of , denoted by , is an undirected graph with vertex set where two distinct vertices and are adjacent if and only if , and there exists a nonzero element of such that , , and . Python is a programming language with simple and easy-to-learn code that can be used to solve problems in algebra and graphs. In this paper, we construct the triple zero graph of ring using Python. Based on the output of the program, several properties of are obtained, such as if and , then is a planar graph, if with is prime numbers, then is a complete graph , and if with is prime numbers and , then is a connected graph.
SUSCEPTIBLE VACCINATED INFECTED RECOVERED SUSCEPTIBLE MODEL: EQUILIBRIA POINTS AND APPLICATION ON COVID-19 CASE DATA IN INDONESIA Widyaningsih, Purnami; Ivanni, Anas; Kurdhi, Nughthoh Arfawi
BAREKENG: Jurnal Ilmu Matematika dan Terapan Vol 18 No 3 (2024): BAREKENG: Journal of Mathematics and Its Application
Publisher : PATTIMURA UNIVERSITY

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30598/barekengvol18iss3pp1607-1614

Abstract

Severe Respiratory Syndrome Coronavirus-2 is the infectious agent that causes COVID-19. A vaccine program is an effort to stop the spread of COVID-19 infections in Indonesia. The susceptible vaccinated infected recovered susceptible (SVIRS) model can be used to represent the spread of infectious diseases. This study aims to construct the SVIRS model, identify the equilibria points thus apply it to COVID-19 case data in Indonesia, and determine transmission patterns, model accuracy, and interpretation. Literature and applications are the research methodologies employed. First-order nonlinear differential equations form the obtained SVIRS model. The model has two equilibrium points: a disease-free equilibrium point, and the other is endemic equilibrium point. The SVIRS model on the spread of COVID-19 in Indonesia was obtained using daily secondary data from January 11 to November 30, 2022. The model is solved by the fourth-order Runge-Kutta method. The model’s accuracy is accurate enough to explain the spread of COVID-19 in Indonesia with a mean average percentage error (MAPE) value of 43%. According to the transmission pattern, the number of COVID-19 cases in Indonesia peaked on July 27, 2022, then decreased to zero, obtaining an equilibrium point when no more cases of the disease were present.
Co-Authors Ade Susanti Agus Purnomo Agus Purnomo Aksyarafah, Adifa Yasin Anisatul Farida Bowo Winarno Dewi Retno Sari S Dewi Retno Sari Saputro Dewi Retno Sari Saputro, Dewi Retno Diana Setiani Dwi Purnama Fanny Widadie Firdiana, Intan Hikmah Intan Hikmah Firdiana Istiqlala, Hamda Yauma Ivanni, Anas Meinawati, Rima Nugroho Arif Sudibyo Purboutomo, Bayu Purnami Widyaningsih Putranto Hadi Utomo PUTRI WULANDARI Ririn Setiyowati Ririn Setyowati Rizkita, Nabiella Zahra Rudi Hartono Rudi Hartono S Siswanto Salsabila, Unik Hanifah Santika, Putri Aura Sena, Arya Bima Setiyowati, Ririn Supriyadi Wibowo Sutanto Sutanto Sutanto Tanjung, Andjani Ayu Cahaya Vania, Kezia Abigail Vika Yugi Kurniawan Wijiyanto Yuliana