Judul: Keanekaragaman  dan Komposisi Jenis Kupu-Kupu di Ruang Terbuka Hijau Kota Bekasi, Jawa Barat
Abstrak: Ruang Terbuka Hijau (RTH) menjadi habitat untuk kupu-kupu. Penelitian ini bertujuan membandingkan keanekaragaman dan komposisi jenis kupu-kupu di beberapa RTH Kota Bekasi, Jawa Barat. Pengambilan sampel dilakukan selama tiga bulan di Lahan Batalyon 202, Taman Pemerintah, Alun-alun, Hutan Kota dan Taman Albaziyah, Kota Bekasi, Jawa Barat. Pengamatan dilakukan dengan metode scan sampling dan koleksi kupu-kupu menggunakan jaring serangga dan spesimen diawetkan secara kering. Kupu-kupu yang diamati berjumlah 618 individu dalam 33 spesies dan 4 famili. Leptosia nina merupakan spesies yang dominan. Jumlah individu tertinggi (208 individu) ditemukan di Hutan Kota dan terendah di Taman Albaziyah (93 individu). Keanekaragaman jenis tertinggi ditemukan di Taman Albaziyah (H’=2,55), disusul Hutan Kota (H’=2,49), Alun-alun (H’= 2,23), Taman Pemerintah (H’=2,12), dan Batalyon 202 (H’=1,74). Keanekaragaman kupu-kupu antara Taman Albaziyah dengan Hutan Kota (P=0,70), Taman Pemerintah dengan Alun-alun (P=0,50), dan Alun-alun dengan Hutan Kota (P=0,08) tidak berbeda nyata. Keanekaragaman kupu-kupu antara Alun-alun dengan Taman Albaziyah (P=0,04), Batalyon 202 dengan Taman Pemerintah (P=0,02), Batalyon 202 dengan Alun-alun (P=0,01), Taman Pemerintah dengan Hutan Kota (P=0,01), Taman Pemerintah dengan Taman Albaziyah (P=0,01), Batalyon 202 dengan Hutan Kota (2,76x10-7), dan Batalyon 202 dengan Taman Albaziyah (P=1,04x10-7) berbeda nyata., Green Open Space (GOS) can be a habitat for butterflies. This study aims to compare the diversity and species composition of butterflies in several GOS Bekasi City, West Java. Sampling was carried out for three months at Batalyon 202, Taman Pemerintah, Alun-alun, Hutan Kota and Taman Albaziyah, Bekasi City, West Java. Observations were made using scan sampling method and collection of butterflies using sweep net and the dry preserved was used. Totally 618 individuals from 33 species in 4 families of butterfly were collected. Leptosia nina was the dominant species. Hutan Kota has the highest individuals number (208 individuals) and the lowest in Taman Albaziyah (93 individuals). Taman Albaziyah has the highest species diversity (H’=2,55), followed by Hutan Kota (H’=2,49), Alun-alun (H’=2,23), Taman Pemerintah (H’=2,12), and Batalyon 202 (H’=1,74). Butterfly diversity among Taman Albaziyah with Hutan Kota (P=0,70), Taman Pemerintah with Alun-alun (P=0,50), and Alun-alun with Hutan Kota (P=0,08) was not significantly different. Butterfly diversity among Alun-alun with Taman Albaziyah (P=0,04), Batalyon 202 with Taman Pemerintah (P=0,02), Batalyon 202 with Alun alun (P=0,01), Taman Pemerintah with Hutan Kota (P=0,01), Taman Pemerintah with Taman Albaziyah (P=0,01), Batalyon 202 with Hutan Kota (2,76x10-7), and Batalyon 202 with Taman Albaziyah (P=1,04x10-7) was significantly different.
Keyword: Hutan Kota, Individu, Spesies, Taman Albaziyah

Judul: Faktor-Faktor Lingkungan Penentu Keanekaragaman Kupu-Kupu di Hutan Kota Srengseng, Jakarta Barat
Abstrak: Faktor-faktor lingkungan penentu yang memengaruhi keanekaragaman kupu-kupu di Hutan Kota Srengseng dapat menjadi informasi dasar pengelolaan habitatnya. Penelitian bertujuan mengukur faktor lingkungan penentu (pakan larva, pakan kupu-kupu, tumbuhan shelter, suhu, kelembapan, Leaf Area Index, kecepatan angin, kebisingan, dan sumber air) serta menganalisis hubungannya dengan keanekaragaman kupu-kupu. Mengukur keanekaragaman, kekayaan, kemerataan, kesamaan, dominansi, menggambarkan sebaran spasial kupu-kupu berdasarkan perbedaan kondisi biofisik tapak. Hasil penelitian menemukan area depan dipengaruhi tumbuhan shelter, pakan kupu-kupu, pakan larva, kebisingan, kecepatan angin, suhu. Area belakang dipengaruhi sumber air, kelembapan, LAI. Area tengah tidak dipengaruhi faktor lingkungan apapun. Sebanyak 36 jenis kupukupu dari 5 famili ditemukan: Hesperiidae 3 jenis, Lycaenidae 8 jenis, Nymphalidae 14 jenis, Papilionidae 5 jenis, Pieridae 6 jenis. Keanekaragaman dan kekayaan jenis tertinggi diperoleh area depan (H’= 3,063; Dmg= 6,435), kemerataan jenis tertinggi diperoleh area tengah (E= 0,664), kesamaan jenis tertinggi diperoleh area tengah dan belakang (Sj= 0,62). Area depan merupakan lokasi paling mendukung keanekaragaman kupu-kupu karena didukung faktor tumbuhan pakan larva dan kupu-kupu, tumbuhan shelter, LAI, dan sumber air., Determinant environmental factors affecting butterfly diversity in Srengseng City Forest could be used as information for its habitat management. Research aimed to measure determinant factors (larval and butterfly foodplant, shelter plant, temperature, humidity, Leaf Area Index, wind speed, noise, water sources) as well as analyzing their relationship with butterfly diversity. Measure diversity, richness, evenness, similarity, dominance and spatial distribution of butterfly species based on site biophysical conditions differences. Results found front area affected by shelter plants, butterfly and larval foodplants, noise, wind speed, temperature. Back area affected by water source, humidity, LAI. Middle area was not affected by any environmental factors. As many as 36 species of butterflies from 5 families were found: Hesperiidae 3 species, Lycaenidae 8 species, Nymphalidae 14 species, Papilionidae 5 species, Pieridae 6 species. Highest diversity and richness in front area (H'= 3,063; Dmg= 6,435), highest evenness in middle area (E= 0,664), highest similarity in middle and rear area (Sj= 0,62). Front area supported butterfly diversity the most because it was supported by foodplants for larvae and butterflies, shelter plants, LAI, and water source.
Keyword: butterflies, diversity, Srengseng Urban Forest

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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