Judul: Kajian Pengelolaan Hutan Rakyat Sengon (Paraserianthes falcataria (L) Nielsen): Kasus Desa Kesenet, Kecamatan Banjarmangu Kabupaten Banjarnegara
Abstrak: This research aims to study the management and cultivation of sengon community forest, to presume its potential, and also to calculate the contribution of sengon and other agroforestry plants toward the farmer’s total income in Kesenet Village, Banjarmagu District, Banjarnegara Residence of Central Java. The methods of the data collection used were quantitative and qualitative method. The quantitative method was used to measure the dimension of sengon and other agroforestry plants with sixty sampling plots in 0,1 hectare of circle shape which were determined by using purposive sampling with 3,10% sampling intensity. The qualitative method was used to analyze the forest management by interviewing through questionnaires to the sixty chosen farmers who own sampling plots and by studying literature. In general, the forest management in Kesenet Village applied the land preparation and management, seeding, planting, cultivation, harvesting and marketing. The stages of the management activities have not been completely achieved because of the traditional hereditary system which was still used. The potency of sengon per hectare in Kesenet Village was estimated on the average of 79,27 m3/ha or between 50,99 m3/ha to 107,55 m3/ha. The total area of sengon in Kesenet village was 193,86 ha and then the total wood of sengon was achieved 15.368,24 m3 or between 9.863,66 m3 to 20.872,83 m3. The income contribution of sengon 4,37% and 84,68 % of salak pondoh of total income forest farmer was illustrated that the sengon cultivation still becomes a secondary business for Kesenet villagers. The efforts that should be done to develop the management of sengon community forest are both by intensifying counseling and training the sengon management technique gradually. Besides that, the market information in warranting the stability of a certain cost can make the farmers easier in bargaining position. The countermeasure of the insects, pests, and karat puru disease which have been attacking 80% sengon plants up until now needs to get a serious attention, especially to warrant the developmental continuation of society business in community forest of sengon.
Keyword: 

Judul: Sistem Pengelolaan Hutan Rakyat Jenis Sengon (Paraserianthes falcataria (L) Nielsen) di Desa Burat, Kecamatan Kepil, Kabupaten Wonosobo
Abstrak: Forest is one of renewable resources. The goal of forest management and forest utilization is to increase society welfare without aside it’s sustainable aspect. In fact, there are several things that supposed to be maximal on forest management, especially in community forest. Community forest has simple management it also has diversity on geographical place and treatment from its land holder. With several ways on developing community forest and also more intensive community forest management with sustainable ways together with support capability from community forest resources potency, exertion activity , environmental dynamics and the other factors are expected to form community forest as a certain business strategic that capable to maintain sustainable production and utilization that also put forest sustainable as priority. This research main objective is to learn community forest management and tabulate systemization of sustainable production planning of community forest at Burat Village, Kepil Sub-District, Wonosobo Regency, Central Java. Data taken in this research includes primary data from direct interview to land holder as producer, merchant, craftsman industry and timber industry. Secondary data taken from Forestry Department of Wonosobo Regency, Kepil Sub-District office, Burat Village office and internet browsing. Analysis method that use in this research are qualitative analysis for secondary data based on interview result and quantitative analysis for sengon species potency as primary data that taken based on simple sampling technique. Burat Village community forest has a simple management; it is proven by phases of utilization activity including planting, cultivation, harvesting, and marketing that haven’t follow the same pattern of management activity. This is occurring by ineffective management information that implement to all land holders at Burat community forest. There’s also misdistribution on supporting factors such as facility and infrastructure in Burat Village community forest. Institutional system and policy also cannot deliver utmost support for development of Burat Village sengon community forest management. Rotation on every sub-village is determined by range of rotation on existing condition; there are two different rotations which is 6 years rotation (Geger Jeruk and Krungsung sub village) and 7 years rotation (Burat, Kalibarong, Kalinongko, Kaliwang and Krajan sub village). Sustainability concept for every sub village that implemented 6 years rotation is range 1069 – 1118 trees/ha that can be harvest or replant, 3 years period 535 – 559 trees/ha, 1 year period 1178 – 186 trees/ha, 6 months period 89 – 93 trees/ha and for 3 months period 45 – 47 trees/ha. Sustainability concept for every sub village that implemented 7 years rotation is range 226 – 893 trees/ha that can be harvest or replant, 3 years period 97 – 383 trees/ha, 1 year period 32 – 128 trees/ha, 6 months period 16 – 64 trees/ha and for 3 months period 8 – 32 trees/ha.
Keyword: 

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.
Keyword: