Judul: Designing Paddy Leaf Chart Color Digital Based on Arduino Using RGB with Reflectance Methode.
Abstrak: Bagan warna daun padi digital merupakan alat penentu kadar kebutuhan pupuk pada tanaman padi, alat ini memanfaatkan fungsi dari sistem minimum Arduino Atmega 328P, sumber cahaya yang digunakan yaitu RGB light emitting diode (LED) dengan jangkauan panjang gelombang cahaya merah 620–750 nm, cahaya hijau 495–570 nm, cahaya biru 450–495 nm. Sistem kerja alat menggunakan sensor optik yaitu fotodioda sebagai detektor nilai intensitas cahaya yang dipantulkan oleh sampel, data acuan yang digunakan berupa nilai analog to digital converter (ADC) yang dibentuk ke dalam suatu database sebagai nilai pembanding yang disandingkan dengan skala bagan warna daun (BWD) berstandarkan International Rice Research Institute (IRRI). Hasil pembacaan sensor yang ditampilkan lycuid crystal display (LCD) merupakan nilai ADC dari setiap pembacaan nilai reflektansi red, green, blue serta penunjukan skala warna padi yang telah ditentukan kadar kebutuhan pupuknya.
Keyword: Bogor Agricultural University, Institut Pertanian Bogor, IPB, Leaf color chart, Light sensor, Microcontroller, RGB, Mikrokontroler, Sensor cahaya, Karakterisasi sensor, Skala warna

Judul: Pengembangan Sensor Warna Daun untuk Menduga Kebutuhan Pupuk pada Tanaman Padi
Abstrak: Leaf colour is an indicator of plant fertility level which can be used for predicting fertilizer need of the paddy plants. The use of leaf colour chart (LCC) is one of instruments to measure greenness level. This research used image processing technology for analysing leaf colour level according to the IRRI-LCC standard. Taking the image of paddy leaves used a cart which is equiped with a proximity sensor and a CCD camera. Proximity sensor functions sending a signal to the camera to capture an image at every certain travelling distance. The captured images were then saved in the hard disk memory. Furthermore, those images were processed with Visual Basic program for analysing leaves area and greenness level. Then, the results were transformed into an area colour map, where each patch of land contains information about fertilizer need. Beside analysing with image processing, the measurement of leaf colour level was also done manually. The result of the manual measurement was also translated into an area colour map. The results of the manual and image processing measurement were then compared for determining the accuracy level. Accuracy at the colour level 2 was 38%, the colour level 3 was 69%, and the colour level 4 was 75%. The correlation between leaf colour level and nutrient content of soil was observed by comparing the result of soil nutrient content test and leaf colour level. It was found that both averages show a strong correlation
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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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