Judul: Analysis of Candlenut Tree Management in Tanah Pinem District, Dairi Regency, North Sumatera Province
Abstrak: One orientation in the long-term development of forest by the Indonesian government is the resulted welfare and active role of the people in forest management by expanding the people’s forest acreage. The type of plants selected for the community’s forest that will be developed must be suited to the local environmental conditions in terms of technical, economic, ecological, social and cultural aspects so that economically the activities of community’s forest can become the people’s choice of productive and sustainable business activities. Candlenut is one of the trees growing in the community environment. Economically the plants are very beneficial as their income sources and ecologically can serve to improve the functions of environment. The objectives of this study were (1) to determine the influential factors in the management candlenut trees and (2) to examine the sustainability of the people’s candlenut tree management for the ecological, economic and social aspects. The data was analyzed with a binary logistic regression and the sustainability analysis includes ecological, economic and social aspects. The factors that affect the candlenut management are age, land size, income, land origin, and land accessibility. The sustainability of candlenut management falls into the category of “sustainable with some considerations” based on “Lembaga Ekolabel Indonesia” standard because the community’s management of candlenut has not indicated a continuous or sustainable management.
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Judul: Income of Candlenut Farmes and a Model for Estimating the Weight of Candlenuts (Aleurites moluccana) in Sigi Regency, Central Sulawesi
Abstrak: Kemiri merupakan hasil hutan bukan kayu yang bernilai ekonomi tinggi bagi masyarakat. Akan tetapi, penelitian mengenai hubungan antara dimensi pohon dan berat kemiri belum banyak dilakukan. Penelitian ini bertujuan menghitung rata rata pendapatan petani kemiri, menganalisis hubungan berat kemiri dengan dimensi pohon dan menyusun model penduga berat kemiri. Model disusun menggunakan regresi linier dan non linier. Hasil penelitian menunjukkan bahwa rata-rata pendapatan yang diperoleh petani sebesar Rp2.510.460,53/ha/bulan, variabel dengan keeratan hubungan tertinggi terhadap berat kemiri adalah umur dan lebar tajuk sedangkan model terbaik dalam menduga berat kemiri adalah model M3a dengan persamaan B = 2,070+0,004*T^2*U. Model tersebut dapat menjelaskan variasi berat kemiri sebanyak 41% dengan AIC 755,46, dan RMSE sebesar 13,02 kg/bulan. Selain itu, model tersebut telah memenuhi asumsi homoskedastisitas dan normalitas sisaan., Candlenut is non-timber forest product that have high economic value for the community. However, there has not been much research on the relationship between tree dimensions and candlenut weight. This study aims to calculate the average income of candlenut farmers, analyze the relationship between candlenut weight and tree dimensions and compile a model to estimate the weight of candlenut. The models were arranged using linear and non-linear regression. The results showed that the average income obtained by farmers was Rp2,510,460.53/ha/month, the variables with the highest relationship with the weight of the candlenut were age and width of the crown while the best model in estimating the weight of the candlenut was the M6 model with the equation B = 2,070+0,004*T^2*U. The model can explain the variation in candlenut of 41% with AIC of 755,46, and RMSE of 13,02 kg/month. In addition, the model has met the assumptions of residual homoscedasticity and normality
Keyword: dimensi pohon, kemiri, model penduga berat

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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