Judul: Pengembangan metode cepat pendugaan kandungan protein kasar pada Rumput Raja (Pennisetum purpupoides) dan Brachiaria humidicola menggunkan leaf color chart
Abstrak: The objective of this experiment was to develop the rapid method for estimating crude protein content of king grass (Pennisetum purpupoides) and segnal grass (Brachiaria humidicola) using SPAD cholofil meter and leaf color chart. The study was arranged in a completely randomized design with four treatments and five replications. The two species grass were fertilized with difrent level of urea were PO (0 kg N ha-1/control), P1 (60 kg N ha-1), P2(120 kg N ha-1) and P3(180 kg N ha-1). Parameters observed were crude protein content, leaf color and chorophil. The result showed that fertilization significanly effect crude protein, leaf color and chlorofil countent of leaf. Leaf color chart, chlorofil countent of leaf and crude protein have an positif corelation with the increasing of urea level.
Keyword: crude protein., leaf color chart, Brachiaria humidicola, Penisetum purpupoides, Bogor Agricultural University (IPB)

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: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
Keyword: