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: Pemanfaatan raspberry Pi sebagai alat uji kadar nitrogen dan fosfor pada pupuk
Abstrak: Pupuk memiliki peranan yang penting dalam meningkatkan produktivitas pertanian. Namun, di Indonesia banyak terdapat produk pupuk palsu yang sulit diidentifikasi oleh petani. Sebagai bentuk upaya pengawasan pupuk, Balai Penelitian Tanah telah mengembangkan perangkat uji pupuk (PUP) untuk mengukur kadar hara N dan P dalam pupuk secara cepat. Namun, pembacaan hasil ujinya masih manual dengan menggunakan bagan warna, sehingga hasil pengukurannya masih bersifat semi kuantitatif. Penelitian ini bertujuan untuk mengembangkan PUP sehingga pembacaan warna larutan pupuk dapat dilakukan secara digital dan diharapkan dapat meningkatkan ketelitian hasil pengukuran. Raspberry Pi digunakan sebagai otak yang bertugas untuk mengakuisisi citra larutan pupuk, mengolahnya, dan mengklasifikasikannya ke kadar hara tertentu. Model warna yang digunakan untuk mengolah data citra larutan pupuk adalah model warna hue saturation value (HSV), sedangkan algoritme klasifikasi yang digunakan adalah k-nearest neighbour (KNN). Hasil penelitian menunjukkan bahwa komponen warna yang cocok untuk diambil sebagai penfitur klasifikasi adalah komponen hue, karena tidak terpengaruh oleh perubahan intensitas cahaya pada citra yang diambil. Akurasi tertinggi yang diperoleh untuk N Titrisol sebesar 58.33%, RMSE = 1.43 dengan k = 3, untuk N Urea sebesar 70%, RMSE = 3.32 dengan k = 5 dan untuk untuk P SP-36 sebesar 18.33%, RMSE = 5.79 dengan k = 3.
Keyword: hue saturation value (HSV), kadar hara, k-nearest neighbour (KNN), perangkat uji pupuk

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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