Judul: Model Penduga Biomassa Pohon Agathis (Agathis loranthifolia) Berdiameter Kecil di Hutan Pendidikan Gunung Walat, Sukabumi, Jawa Barat
Abstrak: One of the tree species for rehabilitation in Gunung Walat University Forest (GWUF) is agathis (Agathis loranthifolia). The biomass of small diameter agathis (≤ 10 cm) can be estimated by using Biomass Expansion Factor (BEF) and allometric biomass model, either for each tree component (stem, branches and twigs, and leaves) or for the total of above ground biomass. Based on data analysis using 32 sample trees, the stem biomass was 74%, branch biomass was 16%, and leaf biomass was 10%. The BEF of small diameter agathis was 1.075 (for lower wood density (WD)), 1.022 (for medium WD), and 0.944 (for higher WD). The allometric biomass models for each tree component and total biomass are Wstem = 0,0139dp3,132 (R2 = 99,2%), Wbranches and twigs = 0,0042dp2,963 (R2 = 97,3%), Wleaves = 0,0115dp2,276 (R2 = 97,1%), and Wtotal = 0,0276dp2,945 (R2 = 99,0%), where dp is collar diameter
Keyword: small diameter, biomass expansion factor (BEF), biomass, allometric models, Agathis loranthifolia

Judul: Model Alometrik Biomassa Puspa (Schima wallichii Korth.) Berdiameter Kecil di Hutan Pendidikan Gunung Walat, Sukabumi
Abstrak: One of tree species in Gunung Walat University Forest (GWUF) is schima (Schima wallichii Korth.). Schima can produce timber and absorb carbon dioxide emission from the atmosfer. The objective of this study was to determine biomass expansion factor (BEF) and biomass conversion and expansion factor (BCEF) and to develop allometric biomass model for small diameter of schima. This study used destructive sampling method to measure biomass of 30 sample trees. The biomass content of stem, branch, and leaves of schima was 76.13%, 14.34%, and 9.53% respectively. The average BEF value of schima was 1.36, while the average BCEF value was 626.03 kg/m3. Allometric biomass models for stem, branch, leaves, and total aboveground biomass of schima were Wstem = 0.128DBH2.244, Wbranch= 0.021DBH2.342, Wleaves = 0.032DBH1.928, and Wtotal = 0.178DBH2.222 respectively.
Keyword: small diameter, schima biomass, BCEF, BEF, allometric model

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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