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: Rancang Bangun Alat Elektronik Pengukur Indeks Warna Daun Padi Untuk Rekomendasi Pemupukan Nitrogen
Abstrak: Nondestructive nitrogen monitoring for rice leaf is necessary for applying site specific nitrogen recommendation. Electronic SPAD chlorophyll meter device from Konica Minolta and IRRI-Leaf Color Chart now is the most known tools for measuring rice leaf index which have correlated reading with leaf nitrogen content. Both device is using leaf color properties principles to gave index value for estimating leaf nitrogen content. In this research, a new Prototype of leaf color measurement portable device has been build using TAOS TCS230 RGB Color Sensor. This device is using white LED light source to get reflection from rice leaf. Value read from sensor within range 400-600 nm will be processed in microcontroller to gave color value, leaf index and nitrogen fertilizer amount to be applied in the rice field. Performance test result indicate that the device has worked well on distinguishing colors as calibrated with GretagMacbeth color patch. Using BWD calibration the devices display XYZ and RGB color value as well as the BWD unit and fertilizer recommendation.
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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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