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All Journal POSITRON BULETIN FISIKA
Irfana Diah Faryuni
Universitas Tanjungpura
Astronomy Energy Materials Science & Nanotechnology Medicine & Pharmacology Physics

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Kebergantungan Sifat Fisis dan Mekanis Papan Komposit Berbahan Dasar Sabut Pinang dan Sabut Kelapa pada Variasi Struktur Irfana Diah Faryuni; Mentarie Resthu Putri; Asifa Asri; Nurhasanah Nurhasanah
POSITRON Vol 10, No 1 (2020): Vol. 10 No. 1 Edition
Publisher : Fakultas Matematika dan Ilmu Pengetahuan Alam, Univetsitas Tanjungpura

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (436.723 KB) | DOI: 10.26418/positron.v10i1.35873

Abstract

Pada penelitian ini, telah dibuat papan komposit dengan kandungan serat sabut pinang (Areca catechu L.) dan partikel sabut kelapa (Cocos nucifera L.) yang keduanya berperan sebagai filler. Selain itu, digunakan urea formaldehyde (UF) sebagai matriks, parafin untuk penghambat air, serta NH4Cl sebagai katalis. Struktur papan komposit divariasikan sebanyak 2 jenis, yaitu struktur homogen dan sandwich yang akan diuji sifat fisis dan mekanisnya dengan menggunakan standarisasi Japanese Industrial Standars (JIS) A 5908-2003. Struktur homogen terdiri dari 3 sampel, yaitu 100% serat sabut pinang, 100% partikel sabut kelapa, dan 50% serat sabut pinang dicampur 50% partikel sabut kelapa. Pada struktur sandwich terdapat 2 sampel, yaitu 25% serat sabut pinang sebagai face dan back serta 50% partikel sabut kelapa sebagai core dan 25% partikel sabut kelapa sebagai face dan back serta 50% serat sabut pinang sebagai core. Hasil penelitian menunjukkan sampel sandwich dengan susunan 25% serat sabut pinang sebagai face dan back serta 50% partikel sabut kelapa sebagai core, merupakan sampel yang paling baik yakni memiliki nilai kerapatan 641,36 + 18,03 kg/m3, kadar air 9,88 + 0,49 %, daya serap air 118,74 + 25,61 %, pengembangan tebal 48,82 + 8,44 %, modulus of elasticity 767,90 + 35,41 MPa, modulus of rupture  14,45 + 4,57 MPa, dan internal bonding 0,17 + 0,04 MPa. 
Prediction of PM2.5 Concentration Using Ensemble Machine Learning in Pontianak City Irfana Diah Faryuni; Joko Sampurno
BULETIN FISIKA Vol. 27 No. 2 (2026): BULETIN FISIKA
Publisher : Departement of Physics Faculty of Mathematics and Natural Sciences, and Institute of Research and Community Services Udayana University, Kampus Bukit Jimbaran Badung Bali

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24843/BF.2026.v27.i02.p09

Abstract

Fine particulate matter (PM2.5) is a key indicator of air quality, profoundly impacting human health and the environment. Pontianak City, located in the equatorial tropics of Indonesia, faces recurring air quality challenges driven by local meteorological variability and seasonal biomass burning in the surrounding regions. This study developed an hourly PM2.5 prediction model using an ensemble machine learning approach that integrates Random Forest (RF) and Extreme Gradient Boosting (XGBoost) algorithms. The dataset comprised hourly observations aggregated into hourly values from August 2024 to August 2025, including PM2.5 concentrations and three meteorological predictors: temperature, relative humidity, and atmospheric pressure. Correlation and mutual information analyses revealed that temporal features, notably lagged PM2.5 and 24-hour rolling averages, exerted the strongest influence on current PM2.5 levels, whereas meteorological variables contributed marginally in a nonlinear manner. Model evaluation demonstrated that the Hybrid Ensemble (Stacking RF–XGB) achieved the best performance with R² = 0.72, MAE = 9.71 µg/m³, and RMSE = 22.79 µg/m³, outperforming individual models (RF: R² = 0.69; XGBoost: R² = 0.65). The hybrid model effectively captured temporal fluctuations and extreme pollution events, offering improved robustness and generalization. These results highlight the potential of ensemble-based machine learning to enhance short-term air quality forecasting systems in tropical regions, providing valuable support for public health management and early warning strategies in Pontianak and similar urban environments in the future.
Co-Authors Asifa Asri Joko Sampurno Mentarie Resthu Putri Nurhasanah Nurhasanah