Judul: Prekalibrasi Rumput Gajah Menggunakan NIRS dan Perbandingannya dengan Pengujian Kimia
Abstrak: Penelitian menggunakan near infrared reflectance spectroscopy (NIRS) masih terbatas di Indonesia. Basis data yang digunakan juga masih mengandalkan data dari negara beriklim sedang. Penelitian ini bertujuan untuk membandingkan hasil dari analisis kimia dengan NIRS dan membuat kalibrasi dengan data lokal. Sampel rumput gajah (Pennisetum purpureum) dikumpulkan dan dilakukan analisis kimia untuk mengetahui kandungan nutrien seperti kadar air, abu, protein kasar (PK), serat kasar (SK), neutral detergent fiber (NDF) dan acid detergent fiber (ADF). Data hasil analisis kimia digunakan untuk proses kalibrasi dan validasi NIRS. Kalibrasi dan validasi menggunakan spektrum yang telah dilakukan pemindaian dengan Buchi NIRFlex N-500. Keakuratan NIRS dapat dilihat dari koefisien determinasi (R2) dan standar eror (SE). Hasil yang didapatkan pada penelitian ini menunjukkan bahwa NIRS dengan data lokal cukup akurat untuk memprediksi kandungan nutrien rumput gajah lokal.
Keyword: analisis kimia, NIRS, Pennisetum purpureum, spektrum

Judul: Pengembangan Database NIRS Pedeteksi Komposisi Kimia dan Fraksi Serat Rumput Alam
Abstrak: Rumput alam adalah jenis rumput yang sudah lama beradaptasi dengan tanah dan iklim di Indonesia. Penggunaan NIRS menggunakan basis data yang mengandalkan data dari negara beriklim sedang. Penelitian ini bertujuan menganalisis komposisi kimia rumput alam menggunakan NIRS dan pengembangan database dengan kalibrasi data komposisi kimia rumput alam. Sebanyak 100 sampel rumput alam dikumpulkan dan dilakukan analisis kimia untuk mengetahui kandungan nutrien seperti Berat Kering (BK), abu, protein (PK), serat kasar (SK) dan lemak kasar (LK), dan fraksi serat untuk mengetahui kandungan neutral detergent fiber (NDF) dan acid detergent fiber (ADF). Data hasil analisis kimia digunakan untuk proses kalibrasi dan validasi database NIRS. Model NIRS dibuat dengan menggunakan regresi PLS (partial least square). Kalibrasi dan validasi menggunakan spektrum yang telah dilakukan pemindaian dengan Buchi NIRFlex N-500. Keakuratan NIRS dapat dilihat dari koefisien determinasi, standar eror dan nilai RPD. Hasil penelitian menunjukkan bahwa prediksi NIRS terbaik untuk parameter BK dan abu sedangkan paling rendah untuk parameter PK. Nilai R2, RPD dan PRL untuk BK dan PK berturut-turut R2 (0.8 dan 0.4), RPD (2.8 dan 1.3) dan PRL (0.6 dan 0.1). Kalibrasi internal memperlihatkan bahwa hasil analisis kimia tidak berbeda dengan pengujian menggunakan NIRS pada parameter abu, LK, SK dan NDF, namun masih berbeda pada BK, PK dan ADF. Dari penelitian ini disimpulkan bahwa database NIRS yang dikembangkan dapat digunakan untuk memprediksi abu, LK, SK dan NDF namun belum bisa untuk BK, PK dan ADF. Disarankan untuk menambah jumlah sampel dan analisis laboratorium yang lebih akurat untuk meningkatkan akurasi prediksi BK, PK dan ADF menggunakan NIRS., Natural grass is a type of grass that has long adapted to the soil and climate in Indonesia. The use of NIRS uses a database that relies on data from temperate countries. This study aims to analyze the chemical composition of natural grass using NIRS and develop a database with calibration of the chemical composition and fiber fractions of natural grass data. A total of 100 samples of natural grass were collected from Bogor Municipality and Regency. The sample was analyzed for its nutrient content to determine dry matter weight (DM), ash, crude protein (CP), crude fiber (CF), ether extract (EE), neutral detergent fiber (NDF) and acid detergent fiber (ADF). The data from the chemical analysis were used for the NIRS calibration and validation process. The NIRS model was made using PLS (partial least square) regression. Calibration and validation using a spectrum that has been scanned with the Buchi NIRFlex N-500. The accuracy of NIRS can be seen from the coefficient of determination, standard error, and RPD value. The results obtained by NIRS are used to predict the chemical components of natural grass. The best NIRS prediction results for the DM and ash parameters while the lowest for the CP parameters. The R2, RPD, and PRL for DM and CP estimation were R2 (0.8 dan 0.4), RPD (2.8 dan 1.3) dan PRL (0.6 dan 0.1) respectively. External validation test showed that chemical analysis results were similar to NIRS for ash, EE, CF and NDF parameters but different for DM, CP and ADF parameters. It is concluded that the NIRS
Keyword: Natural Grass, NIRS, Proximate, Spectra

Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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