Judul: Aplikasi Perangkat Uji Pupuk Berbasis Android Menggunakan Fitur Warna
Abstrak: The distribution of counterfeit fertilizer has bring many disadvantages to farmers. To overcome this issue, the Ministry of Agriculture has developed the Fertilizer Test Kit that can be used directly in the field. However, the categorization of nutrient levels are still done manually by using a color chart. Therefore the nutrient level classes are limited to 2.5%, 5%, 10%, 15%, and 20%. The purpose of this research is to improve the classification of fertilizer nutrient level, both from the precision and simplicity. K-Nearest Neighbors (kNN) is used as the classification method with k = 3, 6, and 9. The histrogram of hue component in HSV color space is treated as the feature. Classification is done with 2% resolution to Nitrogen (N) and Phosphorus (P) nutrient levels. The results showed that the best accuracy is 79.54% for N with a root mean square error value (RMSE) of 1.59 and 30% for P with RMSE 4,764. Both were obtained at k = 9.
Keyword: Bogor Agricultural University (IPB), k-nearest neighbour (kNN), Hue Saturation Value (HSV), fertilizer test kit

Judul: Aplikasi Bagan Warna Daun untuk Optimasi Pemupukan Tanaman Padi Menggunakan k-Nearest Neighbor
Abstrak: The leaf color of rice is closely associated with the adequacy of nitrogen (N) level of the ground. N deficiency symptoms that are most obvious and commonly seen is the reduction of green color of the leaf. This research developed a mobile application to identify the color of rice leaf and to determine the appropriate fertilizer. The application was built by using the histogram feature of several color components namely Red, Green, Blue in the RGB color space, Hue, Saturation Value in the HSV color space, and grayscale. K-Nearest Neighbor was choosen as the classification method. This research showed the highest average accuracy of 90.63% on the G (green), V (Value) and grayscale color component. The k-NN classification method produced the highest average accuracy of 72.62% when the value of k is equal to 3.
Keyword: Android, grayscale, histogram, HSV, color identification, k-Nearest Neighbor

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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