Judul: Analisis Distribusi dan Kecukupan Luasan Hutan Kota sebagai Rosot Karbondioksida dengan Aplikasi Sistem Informasi Geografi dan Penginderaan Jauh di Kota Pematangsiantar, Sumatera Utara
Abstrak: Pematangsiantar city as central of government has been facing dynamical change in many aspects such as technological, economical, social-cultural and demographical. The condition lead to open space conversion into industrial area, settlements, offices and other economic activities and increase vehicle numbers. The land conversion and high number of vehicle have increased carbon dioxide (CO2) emission. It is predicted that the pollution may decrease the quality of life environment in Pematangsiantar. One of the effective and efficient solutions to overcome this impact is to implement concept of urban forest in land-use plan. The aim of this study is to estimate the emission of CO2 and analyze the distribution and sufficiency of urban forest in Pematangsiantar during 2009. Hopefully, the result of this study can give information and input to the Local Government of Pematangsiantar and give alternative of solution in the urban forest development. It also gives an overview about the distribution of urban forest an each subdistrict in Pematangsiantar. This study was conducted in Pematangsiantar, the province of North Sumatera during July to September 2009. The data that collected consisted of the consumption level of fuel (oil and gas), total and kind of cattle, width of rice field area and types of land cover of Pematangsiantar. The result shows the emission of CO2 from energy is 261,285 Gg CO2/year, emission from cattle is 0,301 Gg CO2/year and emission from farm is 1,144 Gg CO2/year. The total of emission is 262,73 Gg CO2/year. Based on the landsat image and field condition , Pematangsiantar can be classified into 8 types of land cover. The area of urban forest (high vegetation) numbers is 1.161,45 ha (14,49%), built area is 2.384,64 ha (29,75%), farming area (rice field, dry farm, plantation, bushes, grass land) is 3.412,53 ha (42,57%) and area for infrastructure building 1.057,68 ha (13,16%). The need of urban forest area in Pematangsiantar can be estimated through CO2 absorption approach. Based on CO2 emission calculation, Pematangsiantar city needs 4.509,8 ha (56,26%) for urban forest while the available urban forest in Pematangsiantar is only 1.161,45 ha. Due to emission of CO2 in Pematangsiantar, the city needs more area for urban forest of about 3.345 ha more.
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Judul: Penentuan Luas Optimal Hutan Kota Berdasarkan Rosot Gas Karbondioksida (CO2) di Kota Medan Provinsi Sumatera Utara.
Abstrak: Medan is one of the metropolitan city in Indonesia, which continues to grow as a center of activity of the economy, industry, trade and services. This prompted an increase in energy consumption and discharge residual energy such as gas carbon dioxide (CO2) into the atmosphere. Increasing carbon dioxide has led earth's global temperature increase. One alternative solution to reduce CO2 emissions in the atmosphere is the development of the urban forest. This study aims to determine the optimal area of urban forest by sinks of CO2 gas produced by human use of fossil fuels, livestock and rice cultivation. The study was conducted by literature study, observation, and interpretation and analysis of Landsat image. Carbon dioxide emissions in Medan in 2013 was 2 901.69 Gg so the urban forest area required was 49 807.94 ha. It was predicted that CO2 emissions in 2030 will reach to 1 375 762.80 Gg and therefore the required optimal urban forest area was 23 615 164.42 ha. Today, the urban forest area that available in Medan is only 43.32 ha, so the addition of the urban forest area is still needed.
Keyword: carbon dioxide, emissions, urban forests

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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