Judul: Development of Forest Biomass Estimation Model Based on Sentinel-1 SAR Imagery: A Case Study in the Work Area of PT Trisetia Intiga, Central Kalimantan
Abstrak: Penelitian ini mengkaji pendugaan biomassa hutan lahan kering menggunakan teknologi penginderaan jarak jauh radar. Pendugaan biomassa menggunakan citra SAR Sentinel-1 dengan polarisasi VH dan VV. Penelitian ini menemukan bahwa model penduga terbaiknya adalah B (biomassa) = 132,4 e37,96 RLee_VH*VV dengan nilai koefisien determinasi sebesar 49,1% dan nilai simpangan baku sebesar 0,24. Secara spasial, penelitian ini memperlihatkan bahwa sediaan biomasa tegakan di areal kerja PT Trisetia Intiga yang didominasi oleh hutan lahan kering sekunder mempunyai biomasa dengan kisaran antara 132 ton/ha dan 200 ton/ha., The presence of radar image technology with medium spatial resolution has become a reliable source of data that could be utilized for the forestry and environmental sectors. This study develops the estimation model of dryland forest biomass using radar remote sensing technology. The biomass estimation model was developed using Sentinel-1 SAR imagery with VH and VV polarizations. This study found that the best estimator model is B (biomass) = 132,4 e37,96 RLee_VH*VV with a coefficient of determination of 49,1% and a standard deviation of 0,24. This study shows that the standing biomass stock in the PT Trisetia Intiga concession area, which is dominated by secondary dryland forest, has average of biomass stock between 132 tons/ha and 200 tons/ha.
Keyword: Biomass, Estimation model, Radar, Remote Sensing, Sentinel-1

Judul: Model Penduga Biomassa Hutan Alam Lahan Kering Menggunakan Citra ALOS PALSAR Resolusi 50 M di Areal Kerja PT. Trisetia Intiga
Abstrak: The increase of Green House Gases (GHG), particularly carbon dioxide in the atmospheric is one factor that affect the global warming. One cause of the increase was due to emission of carbon that came from deforestation and land degradation. In the mitigation process for reducing the impact of global warming, one crusial activity is estimation of carbon sequestered in the vegetation. Commonly, carbon content sequestered at vegetation is derived from biomass estimation either from above ground biomass or below ground biomass. In this study, the focus was on estimation of the above ground biomass using remote sensing technology. Nowdays, the development of remote sensing techniques had been widely used for providing various information related to natural resources. Indonesia which is located in the tropical region, have several handicaps in using optical remote sensing due to cloud covers during wet season and smoke and haze during dry season. For the above reason, this study emphasizes on the use of radar image technology for estimating the above ground biomass. In this study the used radar image is ALOS PALSAR (Advance Land Observing Sattelite – Phase Array L-band Synthetic Aperture Radar), that had been launched in Januari 2006 by the Japanese government. This sensor is an active microwave sensor which has capability to penetrate thick cloud layer. An active microwave sensor be accepted dan reflectanced by several diresction that usually called polarization. Polarization is the vector direction from electromagnetic microwave on vertical line (V) and horizontal line (H). The main objective of this study is to develop the biomass estimation model using 50 meter resolution of ALOS PALSAR image in concession of PT. Trisetia Intiga, Central Kalimantan. Biomass model was developed by analyzing the relationship between backscatter value and field biomass. Backscatter value from tree polarization images, namely HH, HV, and HH/HV were analyzed simultaneously with field biomassa that derived using Ketterings allometric equation. In this study the obtained stand structure equation, Y=2482 ℮-0,04X with negative exponential or J-reverse form having realtively steep slope. From the stand structure equation, then it can be concluded that stand condition within the study area is belonged to logged over area secondary forest, where tree density with diameter less or equal to 60 cm is relatively low in comparison with the smaller tree size. From 30 sample plots measured, the above ground biomass is ranged from 68,03 ton/ha to 599,43 ton/ha with coefficient of variation (CV) equal to 50,29%. Proportionaly, the highest biomass is come from tree biomass (64,97%), then followed by biomass of necromass (20,13%), pole biomass (12,16%), sapling biomass (2,75%), litter biomass (3,3x10-5), and undergrowth biomass (5x10-5). The correlation and regretion analyses between backscatter value and field biomass show that there are 38 statistically significant equations having R² ≥ 50%. However, the verification analysis found that only two models identified as the best models having no-significant X²-test, low RMSE (Root Mean Square Error), low bias, and mean deviation < 10%. The best models are: 1) AGB = 3880.40613930209exp (0.250184794335192 HV) with coefficient determination (R²) of 56% and RMSE of 0.47%. 2) AGB = 1022.27050600692 exp (-0.0114464608949151 HV²)
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Judul: Characterizations of low alloy steel sae 4422  plated with chromic acid (Cro3)
Abstrak: Characterizations of low alloy steel SAE 4422 plated with chromic acid (CrOrO3) was use Optical Microscopy (OM), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), RD),Energy Dispersive Analysis of X-Ray (EDAX), Hardness Test and Roughness Test. Microstructures analysis exhibits cracks and grain boundaries microcracks as a characteristics of chrome metal found at plating metal. Perlite and Ferrite as grains of steel found at base metal with grain boundaries around it. Phase analysis of plating metal appropriate to chrome metal with lattice constant (a) is 2.559 Å and phase analysis of base metal appropriate to iron ferrite with lattice constant (a) is 3.318 Å. Both plating and base metal have cubic system. Chemical analysis of plating metal at surface section exhibits that cracks area have highest value of carbon element compare with grains and grains boundaries area. While chemical analysis of base metal at cross section exhibits that perlite have highest value of carbon element compare with ferrite and grain boundaries. The hardness value of plating metal at surface section and cross section are 753 and 637 VHN. While, the hardness value of base metal and interface area at cross section are 205 and 373 VHN. The roughness value at measurement points of chrome surface for as received sample are 0.445 μm. Observation used Optical Microscopy and Scanning Electron Microscopy exhibits surface irregularities combine to form surface texture of plating metal at surface section.
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