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: Hubungan Faktor Lingkungan dengan Keanekaragaman Jenis Kupu-Kupu di Tebet Eco Park, Jakarta Selatan
Abstrak: Populasi kupu-kupu berkaitan dengan faktor lingkungan pada suatu habitat, sehingga rentan terhadap perubahan kualitas lingkungan yang terdiri dari faktor abiotik dan biotik. Tebet Eco Park merupakan Ruang Terbuka Hijau yang sesuai untuk habitat kupu-kupu di tengah perkotaan. Penelitian bertujuan untuk mengkaji keanekaragaman dan komposisi jenis kupu-kupu pada dua area taman dan menganalisis pengaruh faktor lingkungan terhadap keanekaragaman jenis kupu-kupu di Tebet Eco Park. Metode pengumpulan data kupu-kupu menggunakan kombinasi metode transek dan titik hitung serta metode jebakan. Analisis Biplot dan korelasi Pearson digunakan untuk menentukan keeratan hubungan antara faktor lingkungan dengan keanekaragaman jenis kupu-kupu. Terdapat 761 individu dari 27 jenis kupu-kupu yang terdiri dari seluruh famili kupu-kupu tersebar di Taman Utara dan Taman Selatan. Indeks Keanekaragaman Jenis dan Indeks Kemerataan Jenis tertinggi diperoleh Taman Utara pada pagi hari (H’ = 2,524; E = 0,857), namun Indeks Kekayaan Jenis tertinggi diperoleh Taman Selatan pada pagi hari (Dmg = 3,903). Seluruh data keanekaragaman jenis kupu-kupu pada pagi hari lebih tinggi dibandingkan dengan siang hari. Intensitas cahaya matahari berkorelasi negatif sangat kuat terhadap keanekaragaman jenis kupu-kupu., Butterflies act as environmental bioindicators, so they are very susceptible to changes in environmental quality consisting of abiotic and biotic factors. Tebet Eco Park is a green open space that is suitable for butterfly habitats in the middle of urban areas. The research aimed to identify the diversity of butterfly species in two park areas and analyze environmental factors in the two areas that can influence the diversity of butterfly species in Tebet Eco Park. The butterfly data collection method uses a combination of transect and point counting methods and trap methods. Biplot analysis and Pearson correlation were used to determine the close relationship between environmental factors and butterfly species diversity. There were 761 individuals of 27 types of butterflies consisting of all butterfly families spread across North Park and South Park. The highest species diversity index and species evenness index values were found in North Park in the morning (H' = 2.524; E = 0.857), while the highest richness index was found in South Park in the morning (Dmg = 3.903). All data on butterfly species diversity in the morning is higher than in the afternoon. The intensity of sunlight has a very strong negative correlation with the diversity of butterflies.
Keyword: keanekaragaman, kupu-kupu, Taman Selatan, Taman Utara

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: