Judul: Utilitas Hijauan untuk Sapi Perah di Jawa Timur dan Pengembangannya sebagai Database NIRS
Abstrak: Penelitian ini bertujuan untuk mengevaluasi utilitas hijauan dan mengembangkan database NIRS untuk menduga utilitas hijauan. Sebanyak 50 sampel diperoleh dari 5 desa yang terdapat di Kabupaten Magetan. Sampel dikeringkan, digiling dan dianalisis fermentatif (VFA dan NH3), kecernaan in vitro (kecernaan bahan kering (KCBK), kecernaan bahan organik (KCBO)) menggunakan metode Tilley dan Terry (1963), analisis Van Soest residu In vitro (kecernaan NDF (KCNDF) kecernaan ADF (KCADF)) menggunakan fiber analyzer ANKOM 200. Partisi energi (energi bruto (GE), energi tercerna (DE), energi termetabolis (ME), energi neto untuk laktasi (NEL)), nilai hijauan untuk sapi perah (unit hijauan untuk laktasi (UFL), dan nilai relatif hijauan (RFV)) dihitung berdasarkan data fraksi serat dan kecernaan. Spektrum NIRS dikoleksi, dari seluruh sampel sebanyak masing-masing tiga kali. Pada spektrum tersebut diinputkan hasil analisis fermentatif, kecernaan, perhitungan partisi energi dan kualitas hijauan. Kalibrasi dan validasi menggunakan spektrum yang telah dilakukan pemindaian dengan Buchi NIRFlex N-500. Model NIRS dibuat dengan menggunakan regresi PLS (partial least square). Keakuratan NIRS dapat dilihat dari R 2 , standar eror, dan nilai RPD. Untuk kalibrasi eksternal sebanyak 10 sampel hijauan yang berbeda dari proses kalibrasi. Hasil penelitian menunjukkan bahwa rumput alam memiliki kualitas yang baik. Rumput alam memiliki fermentabilitas, kecernaan, partisi energi, dan nilai hijauan yang tinggi. Hasil penelitian menunjukkan bahwa hijauan di Jawa Timur memiliki akurasi yang tinggi. NIRS dapat mendeteksi seluruh parameter secara akurat (R2 >0,5; RPD>1,5)., This study aimed to develop the NIRS database to determine forage utilization for dairy cattle and estimate forage digestibility. As many as 50 samples of forages were obtained five village in Magetan regency. The samples were dried, ground, and analyzed for rumen fermentation (VFA and NH3) and, in vitro digestibility (dry matter (DMD) and, organic matter (OMD)), acid detergen fiber (ADF) and neutral detergent fiber (NDF) from the forage and invitro residues were analyzed using the fiber analyzer ANKOM 200 (to determine their ADF and NDF digestibility (ADFD and NDFD)). The energy partition (gross energy (GE), digestible energy (DE), metabolizable energy (ME), and net energy for lactation (NEL)), unit forage for lactation (UFL), and relative forage value (RFV) were calculated using digestibility and fiber fraction information. The collected NIRS spectrum is calibrated both internally and externally. The NIRS model was made using PLS (partial least square) regression. Calibration and validation were conducted using spectrums that had been scanned with the Buchi NIRFlex N 500.The accuracy of NIRS can be seen from the R2, standard error, and RPD value. For external calibration, 10 samples of different forage were used. The result showed Natural grass was a good quality forage with the highest fermentability, digestibility, energy partition, and forage values. Forage from East Java Province can be detected using NIRS using a developed database with R2>0,5 and RPD>1,5. It is concluded that East Java forage digestibility variation can be detected using NIRS rapidly and accurately
Keyword: hijauan, in vitro, NIRS, prediksi, spektra

Judul: Potential Use of Forage in East Java for Dairy Cattle Based on Chemical Composition and Fiber Fraction
Abstrak: Penelitian ini bertujuan mengevaluasi potensi hijauan di Jawa Timur berdasarkan komposisi kimia dan fraksi serat, serta pengembangannya sebagai database NIRS. Sebanyak 50 sampel hijauan dari Jawa Timur meliputi tebon jagung, klobot jagung, rumput alam, rumput gajah, dan jerami dianalisis proksimat meliputi analisis berat kering (BK), kadar abu, protein kasar (PK), serat kasar (SK), lemak kasar (LK), serta analisis Vansoest meliputi analisis neutral detergent fiber (NDF) dan acid detergent fiber (ADF). Analisis Vansoest dan serat kasar menggunakan alat ANKOM Fiber analyzer. Kalibrasi menggunakan 40 sampel dan validasi menggunakan 10 sampel hijauan yang telah dipindai dengan Buchi NIRFlex N-500. Tahap terakhir adalah validasi eksternal dengan aplikasi Buchi NIRCal 5.2. Penelitian menunjukkan rumput alam menjadi hijauan dengan kandungan nutrien dan fraksi serat terbaik. Keakuratan metode NIRS dapat dilihat dari nilai koefisien determinasi, standar eror dan RPD. Prediksi kandungan nutrien dengan metode NIRS tergolong baik. Hasil prediksi terbaik diperoleh pada parameter abu sedangkan prediksi terendah untuk parameter SK. Hasil uji T dengan hijauan Jawa Timur menunjukkan database dapat mendeteksi seluruh parameter kecuali parameter SK, sedangkan untuk hijauan asal Jawa Barat hanya dapat mendeteksi parameter SK dan ADF. Diperlukan penelitian lebih lanjut dengan variasi sampel beragam dan menyeluruh untuk memprediksi kandungan nutrien hijauan secara akurat., This study aims to evaluate the potential of forage in East Java based on chemical composition and fiber fraction, and development as an NIRS database. 50 forage samples from East Java including 0 samples of maize stover, corn husks, natural grass, napier grass, and rice straw were analyzed proximately including dry matter analysis (DM), ash, crude protein (CP), crude fiber (CF), ether extract contents (EE). and Van Soest analysis includes analysis neutral detergent fiber (NDF) and acid detergent fiber (ADF). fiber fractions and crude fiber were analyzed with ANKOM Fiber analyzer. Calibration using 40 samples and validation using 10 forage samples that have been scanned with Buchi NIRFlex N-500. Lasly, external validation with the Buchi NIRCal 5.2 application. Research shows natural gass becomes forage with the best nutrient content and fiber fraction. The accuracy of the NIRS database can be seen from the coefficient of determination, standard error, and RPD. Prediction using NIRS shows prediction was good, except for the CF parameter. The best prediction results were obtained for the ash parameter. The results of T-test using East Java forage showed database able to detect all parameters except CF, while T-test using West Java forage showed database able to detect some parameter such as CF and ADF. Further research is needed more diverse and comprehensive sampel variations to predict forage nutrient content accurately.
Keyword: NIRS, Prediction, 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.
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