Judul: Estimation of Indonesia's Environment Gross Domestic Product on Forestry Sector
Abstrak: Sektor kehutanan merupakan salah satu sektor yang berkontribusi terhadap Produk Domestik Bruto (PDB) Indonesia. Nilai yang dihasilkan sektor kehutanan berasal dari nilai produksi hasil tebangan kayu dan tidak memperhitungkan kerusakan lingkungan berupa deplesi dan degradasi akibat penebangan pohon. Nilai kerusakan lingkungan tidak tercerminkan dalam PDB sehingga diperlukan PDB lingkungan hidup sektor kehutanan untuk memperhitungkan nilai kerusakan lingkungan tersebut. Penelitian ini bertujuan untuk: (1) mengestimasi deplesi sumberdaya hutan, (2) mengestimasi degradasi sumberdaya hutan, (3) mengestimasi PDB lingkungan hidup sektor kehutanan di Indonesia. Metode analisis yang digunakan pada penelitian ini adalah net price method, analisis kuantitatif, dan benefit transfer. Hasil penelitian menunjukkan bahwa pada periode 2014–2018 deplesi sumberdaya hutan menunjukkan trend yang meningkat, sementara degradasi sumberdaya hutan dan PDB lingkungan hidup menunjukkan trend yang menurun. Pada tahun 2018 deplesi dan degradasi sumberdaya hutan adalah Rp10.039,36 miliar dan Rp761,18 miliar, serta PDB lingkungan hidup Indonesia untuk sektor kehutanan di tahun 2018 sebesar Rp52.181,46 miliar., The forestry sector is one of the sectors that contributes to Indonesia's Gross Domestic Product (GDP). The value generated by the forestry sector comes from the production value of timber harvested and did not calculate the environmental damage such as depletion and degradation due to felling of trees. The value of environmental damage is not reflected in GDP so that environment GDP of the forestry sector is needed to calculate the value of environmental damage. This research aimed to: (1) estimate the depletion of forest resources, (2) estimate the degradation of forest resources, (3) estimate environment GDP of the forestry sector in Indonesia. The analytical method used in this research is net price method, quantitative analysis, and benefit transfer. This research showed that in the 2014–2018 period, the depletion of forest resources showed an increasing trend, while the degradation of forest resources and Indonesia’s environment GDP on forestry sector showed a decreasing trend. In 2018, the depletion and degradation of forest resources were IDR10.039,36 billion and IDR761,18 billion, and Indonesia's environment GDP for the forestry sector was IDR52.181,46 billion.
Keyword: agroforestri, deforestasi, degradasi, deplesi, depresiasi

Judul: The Impact of Forestry Sector Investment on The Indonesian Economy
Abstrak: Indonesia memiliki potensi sumber daya hutan yang besar jika di lihat dari luas kawasan hutan yang mencapai 120 juta hektar. Hal tersebut dapat menjadi modal utama dalam pembangunan. Namun produktivitas sektor kehutanan dan industri pengolahan kayu cenderung mengalami penurunan sehingga membutuhkan adanya investasi. Penelitian ini bertujuan untuk mengetahui keterkaitan dan efek pengganda sektor kehutanan serta dampak investasi sektor industri kehutanan. Metode analisis yang digunakan adalah analisis input-output dengan menggunakan Tabel Input-Output Indonesia tahun 2016 klasifikasi 185 sektor yang diagregasi menjadi 25 sektor untuk analisis keterkaitan dan efek pengganda serta 18 sektor untuk analisis dampak investasi. Hasil analisis menunjukkan terdapat enam subsektor kehutanan yang memiliki kemampuan untuk menarik pertumbuhan produksi sektor hulunya, yaitu bubur kertas, bahan bangunan dari kayu, kayu gergajian dan olahan, kayu lapis dan sejenisnya, barang-barang lainnya dari kayu, gabus, bambu, dan rotan, serta kertas sementara terdapat satu subsektor kehutanan yang memiliki kemampuan untuk mendorong pertumbuhan produksi sektor hilirnya, yaitu kayu. Nilai pengganda output, pendapatan, dan tenaga kerja tertinggi baik tipe I maupun tipe II didominasi oleh subsektor kayu gergajian dan olahan serta subsektor bubur kertas sedangkan nilai pengganda impor tipe I tertinggi terdapat pada subsektor kayu gergajian dan olahan serta nilai pengganda impor tipe II tertinggi terdapat pada subsektor kayu. Dampak dari adanya investasi pada sektor industri kehutanan berpengaruh paling besar terhadap sektor industri kehutanan itu sendiri baik itu output, pendapatan, tenaga kerja dan impor., Indonesia has great potential of forestry resources because the forest’s area reaches up to 120 million hectares. This can be the main capital in the development of the economy. However, the productivity of the forestry sector and the wood processing industry tends to decline which is requiring investment. This study aims to determine the linkages and multiplier effects of the forestry sector and the impact of investment in the forestry industry sector. The analytical method used an input-output analysis using the 2016 Indonesian Input-Output Table for the classification of 185 sectors which are aggregated into 25 sectors for linkage analysis and multiplier effects and 18 sectors for investment impact analysis. The results of the analysis show six forestry sub-sectors that is pulp, building materials from wood, sawn and processed wood, plywood, other goods made of wood, cork, bamboo, and rattan, and also paper can attract growth in the upstream sector while there is one forestry sub-sector that is timber can encourage growth in the downstream sector. The forestry sectors that have the highest output, income, and labor multiplier values are dominated by the sawn and processed wood sub-sector and the pulp sub-sector, while sawn and processed wood sub-sector has the highest type I import multiplier value and wood subsector has the highest type II import multiplier value. The impact of investment in the forestry industry sector has the greatest effect on the forestry industry sector itself, in terms of output, income, labor, and import.
Keyword: Kehutanan, Impor, Input-Output, Investasi, Forestry, Import, Input-Output, Invesment

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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