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All Journal ComEngApp : Computer Engineering and Applications Journal Jurnal Ilmu Komputer dan Informasi ILMU KELAUTAN: Indonesian Journal of Marine Sciences POSITRON Jurnal Neutrino : jurnal fisika dan aplikasinya Jurnal Pendidikan Fisika Indonesia Jurnal IPTEK Jurnal Hukum IUS QUIA IUSTUM Jurnal RESTI (Rekayasa Sistem dan Teknologi Informasi) JIPF (Jurnal Ilmu Pendidikan Fisika) Journal of Physics: Theories and Applications Spektra: Jurnal Fisika dan Aplikasinya JRST (Jurnal Riset Sains dan Teknologi) Jurnal Pertahanan : Media Informasi tentang Kajian dan Strategi Pertahanan yang Mengedepankan Identity, Nasionalism dan Integrity Eksakta : Berkala Ilmiah Bidang MIPA Kappa Journal Journal of Environmental Science and Sustainable Development Jurnal Natural Time in Physics: Journal for Theoretical, Instrumentation, Material-Molecular, and Education Physics Aliansi : Jurnal Politik, Keamanan Dan Hubungan Internasional Scientific Contributions Oil and Gas
Siagian, Ruben Cornelius
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Nonparametric Regression Analysis of BE4DBE2 Relationship with n and z Variables using Naive Bayes and SVM Classification on Nuclear Data Siagian, Ruben Cornelius; Alfaris, Lulut; Muhammad, Aldi Cahya; Nyuswantoro, Ukta Indra Nyuswantoro; Rancak, Gendewa Tunas
Computer Engineering and Applications Journal (ComEngApp) Vol. 12 No. 3 (2023)
Publisher : Universitas Sriwijaya

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Abstract

This research article describes several analyses of nuclear data using various statistical methods. The first analysis uses linear regression to investigate the relationship between the independent variables (n and z) and the response variable (BE4DBE2). The second analysis uses a nonparametric regression model to overcome the assumptions of normality and linearity in the data. The third analysis uses the Naive Bayes method to classify nuclear data based on variables n and z. The fourth analysis uses a decision tree to classify nuclear data based on the same variables. Finally, the article describes an SVM analysis and a K-means analysis to classify and group nuclide data. The article presents clear and organized descriptions of each analysis, including visual representations of the results. The findings of each analysis are discussed, providing valuable insights into the relationships between the variables and the response variable. The article demonstrates the usefulness of statistical methods in analyzing nuclear data.
Analysis of particle dynamics, event horizon, and thermodynamic properties of black holes in the Ghasemi-Nodehi-Bambi metric Siagian, Ruben Cornelius
Jurnal Natural Volume 25 Number 2, June 2025
Publisher : Universitas Syiah Kuala

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Abstract

Black holes, as complex astrophysical objects, are strongly influenced by their metric parameters. This research focuses on the Ghasemi-Nodehi-Bambi (G-N-B) metric, an extension of the Kerr solution, which introduces additional parameters to more accurately describe the properties of black holes. The research investigates the impact of parameter variations in the G-N-B metric on black hole thermodynamics, particle dynamics, and event horizon structure. Analytical and numerical methods are applied to examine the quadratic equations governing event horizons, particle motion, and black hole temperature and entropy. The research explores the variation of parameters (M) and (a) within a certain range to evaluate their influence on the gravitational distribution and the effect of frame attraction. The distribution of (M) values was visualized on a logarithmic scale to highlight the sensitivity of the system to parameter changes. The study found that variations in the G-N-B metric parameter significantly affect the event horizon, with the likelihood of extreme black holes or naked singularities forming depending on the discriminant of the quadratic equation. Particle motion is affected by parameters (M) and (a), which alter the gravitational field and orbital stability. The black hole temperature and entropy show significant changes: an increase in (M) increases gravity and surface temperature, while an increase in (a) decreases temperature due to rotational effects. The research improves the understanding of black holes beyond the Kerr model, especially in terms of black hole thermodynamics and time-space structure.
Approximative Relationship Between The Energy Function (E) and Hubble Function (H) in Cosmology: Practical and Theoretical Analysis Sahroni, Taufik Roni; Pandara, Dolfie Paulus; Wibowo, Arnowo Hari; Alatif, Yahya Halim; Wardana, Febriansyah; Kasim, Mohd Shahir; Siagian, Ruben Cornelius
Jurnal Pendidikan Fisika Indonesia Vol 20, No 1 (2024)
Publisher : Department of Physics, Faculty of Mathematics and Natural Sciences

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jpfi.v20i1.43488

Abstract

This research delves into the approximate relationship between the energy function (E) and the Hubble function (H) within cosmological. Utilizing the Friedmann equation, it establishes a link between the universe's scale factor and the Hubble function. Through Taylor series approximation, the study derives an approximation of the energy function, under specific assumptions and approximations. Asymptotic analysis investigates the behavior of variables y and s, shedding light on function limits and behaviors. The study incorporates an interactive 3D scatter plot visualization to elucidate the relationship between cosmological parameters and physical systems, aiding in a comprehensive understanding of dynamics. Practical recommendations emphasize increasing data points for accuracy and validating with observational data, while theoretical suggestions advocate exploring higher-order terms and considering additional physical factors.
Analysis of Solar Flux and Sunspot Correlation Case Study: A Statistical Perspective Siagian, Ruben Cornelius; Alfaris, Lulut; Nasution, Budiman; Nasution, Habibi Azka
Kappa Journal Vol 7 No 1 (2023): April
Publisher : Universitas Hamzanwadi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29408/kpj.v7i1.12238

Abstract

This analysis examines the relationship between the number of solar flares and the number of sunspots in 2005 using 11 observations in months 2 to 12. The number of solar currents measures the intensity of the radiation emitted by the Sun, while the number of sunspots measures the number of sunspots on the surface of the Sun. Multivariate linear regression analysis was used to analyze the relationship between Solar Current Rate and Number of Sunspots. The results of the analysis show that the coefficient of the Amount of Solar Current is 1.1239 with a significant t value of 2.510 (probability that there is no effect on the Number of Sunspots is 3.33%). The linear regression model has good results with an F-statistic value of 6.301 and a p-value of 0.0333, with an R-squared value of 0.4118 which indicates that 41.18% of the variation in the number of sunspots is influenced by variations in the amount of solar currents. The corrected R-squared value is 0.3464 indicating that there are still variations in the number of sunspots that cannot be explained by variations in the number of solar currents. ARIMA analysis results show an MA coefficient of 0.7351 with an average value of 45.9542 and a s.e value of 0.2590 and 6.1550 respectively. The AIC, AICc, and BIC values are 92.97, 96.4, and 94.16. The error results in the training set show that the ME value is 0.2615561, the RMSE value is 12.16969, the MAE value is 9.03306, the MPE value is -15.14689, the MAPE value is 30.42013, and the MASE value is 0.674109. The ACF1 value in the exercise set is 0.0808969.
Separation of Variables Method in Solving Partial Differential Equations and Investigating the Relationship between Gravitational Field Tensor and Energy-Momentum Tensor in Einstein's Theory of Gravity Siagian, Ruben Cornelius; Alfaris, Lulut; Nurahman, Arip; Muhammad, Aldi Cahya; Nyuswantoro, Ukta Indra; Nasution, Budiman
Kappa Journal Vol 7 No 2 (2023): Agustus
Publisher : Universitas Hamzanwadi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29408/kpj.v7i2.20921

Abstract

This research delves into the study of partial differential equations (PDEs) and gravitational fields in spacetime. It focuses on solving PDEs using the Separation of Variables method and explores the relationship between the gravitational field tensor and the energy-momentum tensor, leading to the final equation for the gravitational field tensor. The research also investigates Einstein's theory of gravity and the energy-momentum tensor integral, providing the general solution for the gravitational potential and its implications. Additionally, the mean integration of the gravitational wave tensor is analyzed, yielding an expression for the tensor strain of gravitational waves over an infinitely long period. The components of the gravitational wave tensor and their effect on gravitational sources are examined. Furthermore, the propagation of electromagnetic fields in spacetime is studied using the Retarded Green's Function. The primary objectives of this research are to understand and explore mathematical techniques for solving PDEs and analyzing gravitational fields and their interactions in spacetime. The integration of multiple theoretical concepts related to PDEs, gravitational fields, and electromagnetic fields enhances our understanding of fundamental physics principles. This contributes to the advancement of theoretical physics and opens avenues for potential practical applications, such as gravitational wave detection and electromagnetic field propagation in complex media. In conclusion, this research provides valuable insights into fundamental physics principles and fosters a deeper understanding of their interconnections and implications
IMPACT OF URBAN DEVELOPMENT ON UV EXPOSURE: A CLUSTERING AND MACHINE LEARNING ASSESSMENT Sahroni, Taufik Roni, Mr.; Yasin, Verdi; Alfaris, Lulut; Ariefka, Reza; Siagian, Ruben Cornelius; Karim, Mohammad Alfin; Rahdiana, Nana; Suhara, Ade
Journal of Environmental Science and Sustainable Development Vol. 7, No. 2
Publisher : UI Scholars Hub

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Abstract

The relocation of Indonesia's capital city is anticipated to promote inclusive economic growth while embracing cultural diversity. However, this transition may affect ultraviolet (UV) radiation exposure patterns. The study investigated variations in UV exposure in the IKN region, focusing on urban development factors such as land use and population density that affect public health, sun protection, and skin cancer prevention. The research hypothesized that UV radiation is significantly correlated with these factors. UV Index data from 2010-2023, a hierarchical clustering method, identifies complex data patterns without determining the number of clusters. XGBoost, a machine learning model, was used for handling high-dimensional data and strong non-linear interactions, outperforming Random Forest in predicting Ultraviolet A variables. Analysis of variance (ANOVA) showed significant inter-group differences, which were validated by Tukey HSD post-hoc tests. Results showed that Cluster 4 was the region with the highest UV exposure. In contrast, Cluster 5 recorded the lowest, with exposure levels ranging from 6.61 to 15.82, a considerable difference of 9.21. The findings underscore the role of geographic and environmental factors in shaping UV exposure patterns, with implications for public health. Areas with high UV exposure face higher risks, including skin cancer and premature ageing. The predictive accuracy of the XGBoost model highlights its usefulness in addressing UV-related health risks. The study advocates for improved UV protection strategies and informed health policies to mitigate climate change impacts and promote sustainable urban development. The findings suggest that the development of data-driven early warning systems for UV radiation exposure could be implemented to improve public health policy and safety.
VOLATILITAS DAN STABILITAS EKONOMI DI NATO DAN BRICS: Analisis Ekonometrik Komparatif Siagian, Ruben Cornelius; Rajagukguk, Michael Haratua
Aliansi Vol 4, No 3 (2025): Aliansi : Jurnal Politik, Keamanan Dan Hubungan Internasional
Publisher : Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/aliansi.v4i3.64007

Abstract

Global economic inequality and geopolitical alliance dynamics are important topics in the study of economics and international relations. Countries belonging to NATO and BRICS have different economic characteristics, which affect their stability and growth in the global market. The research analyzes the volatility of economic production in both groups of countries, and identifies the main factors that cause differences in economic stability between NATO and BRICS. The research is limited to analyzing economic data from NATO and BRICS members over the past two decades. Methods include descriptive statistical analysis and econometric models to measure the level of production volatility and the factors affecting it. Data was obtained from various international sources, such as the World Bank and IMF, to ensure the validity and reliability of the findings. The research shows that NATO countries tend to have higher economic stability than BRICS, which is influenced by more coordinated fiscal and monetary policies, as well as more mature economic infrastructure. In contrast, BRICS countries exhibit higher levels of production volatility due to structural factors. The research gap identified in this study is the lack of comparative studies that directly compare economic volatility between NATO and BRICS using an in-depth quantitative approach. The novelty of the research lies in the integration of econometric models in measuring and comparing the economic volatility of the two groups of countries, as well as providing a new perspective on the impact of geopolitical alliances on economic stability. The research conclusion confirms that economic stability is stronger in NATO countries than BRICS, which has implications for future economic policies and development strategies. The findings can serve as a reference for policymakers in designing economic strategies that are more adaptive to global market dynamics and production volatility risks. Ketidaksetaraan ekonomi global dan dinamika aliansi geopolitik merupakan topik penting dalam studi ekonomi dan hubungan internasional. Negara-negara yang tergabung dalam NATO dan BRICS memiliki karakteristik ekonomi yang berbeda, yang memengaruhi stabilitas dan pertumbuhan mereka di pasar global. Penelitian ini menganalisis volatilitas produksi ekonomi di kedua kelompok negara tersebut, serta mengidentifikasi faktor utama yang menyebabkan perbedaan stabilitas ekonomi antara NATO dan BRICS. Penelitian ini terbatas pada analisis data ekonomi dari anggota NATO dan BRICS selama dua dekade terakhir. Metode yang digunakan meliputi analisis statistik deskriptif dan model ekonometrik untuk mengukur tingkat volatilitas produksi dan faktor-faktor yang mempengaruhinya. Data diperoleh dari berbagai sumber internasional, seperti Bank Dunia dan IMF, untuk memastikan validitas dan keandalan temuan. Penelitian menunjukkan bahwa negara-negara NATO cenderung memiliki stabilitas ekonomi yang lebih tinggi daripada BRICS, yang dipengaruhi oleh kebijakan fiskal dan moneter yang lebih terkoordinasi, serta infrastruktur ekonomi yang lebih matang. Di sisi lain, negara-negara BRICS menunjukkan tingkat volatilitas produksi yang lebih tinggi akibat faktor struktural. Kesenjangan penelitian yang diidentifikasi dalam studi ini adalah kurangnya studi perbandingan yang secara langsung membandingkan volatilitas ekonomi antara NATO dan BRICS menggunakan pendekatan kuantitatif yang mendalam. Keunikan penelitian ini terletak pada integrasi model ekonometrik dalam mengukur dan membandingkan volatilitas ekonomi kedua kelompok negara, serta memberikan perspektif baru tentang dampak aliansi geopolitik terhadap stabilitas ekonomi. Kesimpulan penelitian menegaskan bahwa stabilitas ekonomi lebih kuat di negara-negara NATO dibandingkan BRICS, yang memiliki implikasi bagi kebijakan ekonomi dan strategi pengembangan di masa depan. Temuan ini dapat menjadi acuan bagi pembuat kebijakan dalam merancang strategi ekonomi yang lebih adaptif terhadap dinamika pasar global dan risiko volatilitas produksi.
Re-examining Amnesty and Abolition Practices in Indonesia: A Normative Evaluation and Framework for Procedural Guidance Putra, Steinly Suwanto; Suarda, Gede Widhiana; Rato, Dominikus; Anggono, Bayu Dwi; Siagian, Ruben Cornelius
Jurnal Hukum IUS QUIA IUSTUM Vol. 32 No. 3: SEPTEMBER 2025
Publisher : Universitas Islam Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20885/iustum.vol32.iss3.art8

Abstract

The granting of amnesty and abolition in Indonesia is a presidential prerogative under Article 14 of the 1945 Constitution. Its practice has exhibited complex and diverse patterns throughout Indonesia’s political history, from the Soekarno era to the Prabowo Subianto administration. It has generated controversy regarding the rule of law, substantive justice, transparency, and the protection of victims’ rights. This study aims to analyze the practice of amnesty and abolition from historical and juridical perspectives, evaluate its implications for the principle of the rule of law, and identify potential abuses of presidential discretion. Methods include case studies, comparative juridical analysis, and review of legal documents such as presidential decrees, Article 14 of the 1945 Constitution, court decisions, BPUPKI minutes, and legal literature. The analysis was conducted using historical, normative, and descriptive argumentative approaches. The results show that political considerations often influence the practice of amnesty and abolition, can create a perception of legal uncertainty, and that the DPR plays only a formal role. Patterns of granting amnesties differ by era: political stabilization (Soekarno, Soeharto); political rights rehabilitation (Habibie, Abdurrahman Wahid/Gus Dur); peace integration (SBY); and individual justice and human rights considerations (Jokowi, Prabowo). This research proposes a legal bureaucratic framework to strengthen transparency, accountability, and substantive justice. In conclusion, amnesties and abolitions should be implemented with due regard for justice, transparency, legal certainty, and public oversight to prevent abuse of power and to maintain public trust in the legal system.
Evaluating Global Oil Data Reporting Consistency and Stability with Insights from Indonesia Taufik Roni Sahroni; Lulut Alfaris; Siagian, Ruben Cornelius; Andri Wahyudi; Anas Noor Firdaus; Ukta Indra Nyuswantoro
Scientific Contributions Oil and Gas Vol 49 No 1 (2026)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/scog.v49i1.2010

Abstract

Transparent and consistent oil data reporting is a critical component of global energy governance and market stability. This study evaluates the consistency, stability, and overall quality of global oil data reporting from 2002 to 2025 using the dataset of the Joint Organizations Data Initiative (JODI), with Indonesia employed as a regional reference case. The principal indicators applied include the Index of Reporting Consistency (IRC), the Reporting Volatility Index (RVI), and the Oil Data Availability Index (ODAI). Countries are classified according to market role (producer or importer), economic grouping, and geographical region. The analysis further incorporates K-means clustering and structural change detection to assess temporal stability and responsiveness to major global shocks. The findings reveal substantial variation in reporting performance across countries. Nations exhibiting high IRC values and low RVI scores generally possess more mature institutional and statistical capacities, whereas those with low IRC scores tend to face governance or data management constraints. Oil-producing countries typically demonstrate higher ODAI values but display greater vulnerability to systemic crises, while importing countries show relatively more stable reporting patterns. Major global shocks in 2008, 2014, 2020, and 2022 exerted asymmetric impacts on producers and importers, highlighting structural vulnerabilities within the global energy reporting system. Indonesia demonstrates consistently strong reporting performance, with an ODAI value of 0.944, exceeding the averages of ASEAN (0.889) and OPEC (0.829). The country records a non-reporting rate of only 5.6% and a maximum non-reporting duration of ten months. This study addresses a gap in long-term, shock-sensitive analyses and introduces an integrated framework combining IRC, RVI, and ODAI as a novel approach for assessing oil data reporting quality. The findings provide a foundation for strengthening institutional capacity, enhancing regional coordination, and developing crisis-resilient reporting systems, while positioning ODAI as a practical indicator for evaluating energy governance and policy transparency.
Numerical Analysis of Metric Perturbations, Spacetime Curvature, and Gravitational Wave Polarizations in Linearized General Relativity Using the Finite Difference Method Ariefka, Reza; Siagian, Ruben Cornelius; Sahroni, Taufik Roni; Nurahman, Arip
POSITRON Vol 16, No 1 (2026): Vol. 16 No. 1 Edition
Publisher : Fakultas Matematika dan Ilmu Pengetahuan Alam, Univetsitas Tanjungpura

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26418/positron.v16i1.92372

Abstract

The general theory of relativity states that small perturbations in the spacetime metric in a weak gravitational field can be treated as perturbations propagating on the Minkowski background. Although the analytical formulation of Einstein's linear equations has been well developed, numerical studies that integrate local metric perturbations, the curvature structure of space-time through the Ricci tensor, the dynamics of gravitational wave polarization, and reduction to Newton's law of gravity in a two-dimensional domain are still limited. This research aims to numerically analyze the behavior of metric perturbations and space-time curvature in the framework of linear general relativity and verify its consistency with gravitational wave theory and Newtonian gravity at weak field and low velocity limits. The study is limited to a linearized approach, two-dimensional flat spacetime, harmonic and transverse–traceless gauge conditions, and ideal sources in the form of Gaussian perturbations and source-free waves. The methods used include the theoretical formulation of linearized general relativity and the Finite Difference Method (FDM) numerical approach to discretize the Laplace operator and wave equation with the FTCS scheme. The results show that Gaussian perturbations produce highly localized curvature with a global Ricci tensor contribution approaching zero. Gravitational wave simulations show the dominance of energy in polarization (h_+)\ over (h_\times), as well as numerical verification of the relationship (h_{00}=-2\phi), which confirms the reduction of general relativity to Newton's laws. This research fills a research gap by integrating metric analysis, curvature, and gravitational waves into a single consistent numerical framework. The novelty of this research lies in Gaussian modeling and integrated FDM-based numerical analysis as a conceptual bridge between general relativity and classical mechanics.
Co-Authors Alatif, Yahya Halim Aldi Cahya Muhammad Ali Azhar Andri Wahyudi Ariefka, Reza Aunzo, Jr., Rodulfo T. Bayu Dwi Anggono Budiman Nasution Dominikus Rato Firdaus, Anas Noor Goldbert Harmuda Duva Sinaga Harahap, Veryyon Hassan, Rohana I Gede Widhiana Suarda Jaya, Pratama Jubaidah, Jubaidah Karim, Mohammad Alfin Kasim, Mohd Shahir Laeiq, Nazish Lulut Alfaris Malun, Nicholaus Ola Muannif Ridwan Muhlis, Dasep Nasution, Habibi Azka Novyar Satriawan Fikri, KMS Nurahman, Arip Nyuswantoro, Ukta Indra Nyuswantoro, Ukta Indra Nyuswantoro Pandara, Dolfie Paulus Pribadi, Pandu Purwanto, Romdhon Putra, Steinly Suwanto Rahdiana, Nana Rajagukguk, Michael Haratua Rancak, Gendewa Tunas Rionaldy, Rizqy Sahroni, Taufik Roni Sahroni, Taufik Roni, Mr. Sinaga, Mardame Pangihutan Siregar, Vivi Ariani Suhara, Ade Taufik Roni Sahroni Ukta Indra Nyuswantoro Verdi Yasin Wardana, Febriansyah Wibowo, Arnowo Hari Wibowo, Firdaus Andi winsyahputra Ritonga Yulianto, Tomi