Judul: Pengembangan Model Estimasi Produksi Padi Berbasis Data Sentinel-2A
Abstrak: Tanaman padi adalah salah satu jenis tanaman penghasil bahan pangan pokok masyarakat, bahkan menjadi komoditi pangan utama di Indonesia. Salah satu upaya agar tanaman padi menghasilkan beras dengan kualitas dan kuantitas yang baik dapat melalui cara pemupukan dan pemeliharaan yang baik. Dinamika pertumbuhan tanaman padi pada lahan yang luas, memerlukan metode pemantauan yang efisien terhadap waktu, melalui pendekatan penginderaan jauh dengan resolusi temporal menggunakan indeks vegetasi. Oleh karenanya penelitian ini bertujuan untuk (1) mengetahui respon nilai indeks vegetasi Normalized Difference Vegetation Index (NDVI), Soil-Adjusted Vegetation Index (SAVI), Optimization Soil-Adjusted Vegetation Index (OSAVI), Enhanced Vegetation Index-2 (EVI-2) dan Normalized Difference Red-Edge Index (NDRE) terhadap perlakuan pupuk dan jarak tanam dan (2) mengembangkan model estimasi produksi padi berdasarkan indeks vegetasi. Proses pengamatan lapang dan pengumpulan data dilakukan setiap 10 hari sekali selama satu siklus tanam di Desa Pasirkaliki, Karawang, Jawa Barat. Metode pengembangan model dilakukan berdasarkan analisis pada setiap akumulasi Thermal Heat Unit (THU) yang bersesuian dengan resolusi temporal Sentinel-2A, indeks vegetasi (NDVI, SAVI, OSAVI, EVI-2, dan NDRE) serta Random Forest Regression (RFR). Hasil penelitian menunjukkan bahwa pengaruh perlakuan dosis pupuk berpengaruh signifikan pada fase vegetatif dan fase generatif, ditandai dengan nilai R2 yang tinggi untuk nilai indeks vegetasi NDVI, SAVI, OSAVI, EVI-2, dan NDRE. Selain itu, hasil analisis RFR menunjukkan bahwa NDVI, OSAVI, dan NDRE memiliki performa yang baik untuk memprediksi berat kering gabah hasil panen. Performa model berbasis indeks NDRE menunjukkan akurasi yang lebih tinggi pada akumulasi THU 176°C hari (fase vegetatif) dengan angka persentase sebesar 94,58% dan RMSE 4,14. Performa model berbasis indeks OSAVI menunjukkan akurasi yang lebih tinggi pada akumulasi THU 481°C hari (fase genetatif) dengan angka persentase sebesar 95,05% dan RMSE 3,54. Saran untuk penelitian selanjutnya, menguji kehandalan model estimasi produksi gabah kering panen berbasis indeks NDRE digunakan pada fase vegetatif (akumulasi THU 176°C hari) dan indeks OSAVI digunakan pada fase generatif (akumulasi THU 481°C hari)., Rice plants are one type of plant that produces staple food for the community, even becoming the main food commodity in Indonesia. One of the efforts for rice plants to produce rice with good quality and quantity can be through fertilization and goog maintenance. The dynamics of rice plant growth on a large area of land requires a time-efficient monitoring method, through a remote sensing approach with temporal resolution using vegetation indices. Therefore, this research aims to (1) determine the response of Normalized Difference Vegetation Index (NDVI), Soil- Adjusted Vegetation Index (SAVI), Optimization Soil-Adjusted Vegetation Index (OSAVI), Enhanced Vegetation Index-2 (EVI-2) dan Normalized Difference Red- Edge Index (NDRE) to fertilizer dosage treatment and planting technique and (2) develop a rice production estimation model based on vegetation index. The field observation and data collection were carried out every 10 days during one cropping cycle in Pasirkaliki Village, Karawang, West Java. The model development method is based on the analysis of each Thermal Heat Unit (THU) accumulation that corresponds to the temporal resolution of Sentinel-2A, vegetation index (NDVI, SAVI, OSAVI, EVI-2, and NDRE) and Random Forest Regression (RFR). The results showed that the effect of fertilizer dosage treatment had a significant effect on the vegetative
Keyword: vegetation index, THU accumulation, RFR method, fertilizer dosage

Judul: Development of Empirical Model for Estimation of Rice Nitrogen Accumulation Based on Sentinel 2 Satellite Imagery
Abstrak: Plant Nitrogen Accumulation (PNA) merupakan jumlah total (akumulasi) N dalam tajuk tanaman per satuan luas tanah. PNA adalah sebuah indikator yang menunjukkan status N pada tanaman. Penelitian ini mengusulkan sebuah model empiris untuk menghitung PNA pada lahan sawah yang luas, dengan cepat dan dekat waktu nyata berdasarkan data Sentinel 2. Hasil analisis terhadap hubungan indeks vegetasi dengan data PNA sampel tanaman padi yang diambil dari plot-plot percobaan menunjukkan bahwa status N tanaman padi dapat dideteksi secara dekat waktu nyata menggunakan data Sentinel 2. Analisis statistik juga menunjukkan bahwa variasi temporal dan spasial indeks PNA tanaman padi pada perlakuan teknik tanam dan varietas yang berbeda dapat diestimasi berdasarkan indeks vegetasi dari Sentinel 2. Analisis hubungan data pengukuran PNA tanaman padi dengan delapan metode indeks vegetasi, membuktikan bahwa perhitungan PNA berbasis NDRE merupakan model optimum yang ditunjukkan oleh nilai R2 = 75.17%, RMSE = 22.5 kg/ha, dan akurasi = 80.80% terhadap data training. Validasi model perhitungan PNA berbasis NDRE memiliki performa yang baik dengan 65.08%, RMSE = 45.2 kg/ha, dan akurasi = 74.22%. Model PNA ini telah digunakan untuk memetakan distribusi spasial status N tanaman padi yang berbeda waktu tanaman pada lahan baku sawah Kecamatan Rawamerta, Kabupaten Karawang. Hasil penelitian telah berkontribusi terhadap penerapan prinsip-prinsip pertanian presisi, dengan memberikan landasan penting bagi pengembangan sistem rekomendasi pemupukan berbasis teknologi penginderaan jauh., Plant Nitrogen Accumulation (PNA) is the total amount (accumulation) of N in the plant canopy per unit area of land. PNA is an indicator that shows the N status in plants. This study proposes a method for computing PNA over large areas of rice field, faster and in near real-time based on Sentinel 2 data. The research was proven that the N status of rice plants can be detected in real time using Sentinel 2 data, through empirical analysis of the relationship between the Sentinel 2-based vegetation indices and PNA of rice taken from the experimental plots. Statistical analysis was shown that the temporal and spatial variations of the PNA of rice on different planting techniques and varieties can be determined based on the vegetation indices. Empirical analysis of the PNA based on eight vegetation indices methods were proven that the NDRE-based PNA model was an optimum model, indicated by the value of R2 = 75.17%, RMSE = 22.5 kg/ha, and accuracy = 80.80% to the training data. The performance indicators of the PNA model were calculated with the results of R2 = 65.08%, RMSE = 45.2 kg/ha, and accuracy = 74.22%. The PNA model has been used to map the spatial distribution of the N status of rice plants at different planting stages over rice field area in Rawamerta District, Karawang Regency. The research results have contributed to the application of the principles of precision agriculture, through providing an important basis for the development of a fertilization recommendation system based on remote sensing technology.
Keyword: near real-time measurement, plant nitrogen accumulation, planting technique, rice varieties, vegetation indices

Judul: Penggunaan Teorema Homeomorphy 2-Manifold dan Teorema Euler Poincare pada Torus 𝑇�� dan Simplicial Complex 𝐾��
Abstrak: Two dimensional topological spaces are said to be homeomorphic if they have the same topological invariant, where one of topological invariant used is an Euler characteristic. Homeomorphy 2-Manifold’s Theorem and Euler Poincare’s Theorem are used to distinguish two topological spaces. Homeomorphy 2-Manifold’s Theorem uses Euler characteristic to identify two dimensional topological spaces. Euler Poincare’s Theorem is an alternative way to find Euler characteristic with Betti number, which is topological invariant as well. The objective of this paper is to investigate the homeomorphism of torus 𝑇����� and simplicial complex 𝐾�����. Topological space torus and simplicial complex 𝐾����� have the same Euler characteristic, which is two. Based on Homeomorphy 2-Manifold’s Theorem topological space torus 𝑇����� and simplicial complex 𝐾����� is homeomorphic.
Keyword: simplicial, torus, Euler, homeomorphism, topology