Judul: Identification of Various Accessions of Arabica Coffee (Coffea arabica) Based on Morphological Characters in Small Holder’s Garden, Cikajang District, Garut Regency
Abstrak: Kopi (Coffea sp.) merupakan komoditas perkebunan yang berperan penting dalam kegiatan perekonomian di Indonesia. Umumnya buah kopi Arabika berwarna merah saat matang, namun salah satu kopi yang tumbuh di lahan petani Garut berbuah kuning dan diduga berasal dari tetua kopi berbuah merah, tetapi identitas tetuanya tidak diketahui. Penelitian bertujuan mengidentifikasi berbagai aksesi tanaman kopi Arabika dan menganalisis kekerabatan kopi Arabika berbuah kuning dan berbuah merah melalui karakter morfologi di Kebun Rakyat, Kecamatan Cikajang, Kabupaten Garut. Penelitian dilakukan pada bulan Januari hingga Juli 2022. Lokasi penelitian bertempat di tiga blok Kebun Rakyat, Desa Margamulya, Kecamatan Cikajang. Percobaan dilakukan dengan cara mengidentifikasi karakter morfologi setiap aksesi menggunakan descriptor list IPGRI untuk tanaman kopi yang dimodifikasi. Data kuantitatif dianalisis menggunakan uji ANOVA dan uji lanjut DMRT pada taraf 5%. Data kualitatif dan sebagian data kuantitatif dianalisis menggunakan analisis cluster untuk melihat kekerabatan antar aksesi menggunakan program NTSYS 2.11a. Berdasarkan hasil identifikasi, terdapat delapan aksesi kopi Arabika dengan tiga warna buah yang berbeda yaitu kopi berbuah kuning (A1), berbuah merah (A2, A3, A4, A5, A6, A7) dan berbuah oranye (A8). Hasil dendogram menunjukkan terdapat kekerabatan antara A1 yang berbuah kuning dengan A2 yang berbuah merah pada tingkat kemiripan 75% berdasarkan karakter morfologi yang dimilikinya, Coffee (Coffea sp.) is a plantation commodity that plays an important role in economic activities in Indonesia. Generally, Arabica coffee cherries are red when ripe, but one of the coffees that grows on Garut farmer's land bears yellow fruit and is thought to have come from a red fruit coffee parent, but the identity of the parent is unknown. The aims of this study were to identify various accessions of Arabica coffee plants and to analyze the kinship of Arabica coffee with yellow fruit and red fruit through morphological characters in the Small Holder's Garden, Cikajang District, Garut Regency. The research was conducted from January to July 2022. The research location was located in three blocks of the People's Garden, Margamulya Village, Cikajang District. The experiment was carried out by identifying the morphological characters of each accession using the IPGRI descriptor list for the modified coffee plants. Quantitative data were analyzed using the ANOVA test and the DMRT follow-up test at the 5% level. Qualitative data and part of the quantitative data were analyzed using cluster analysis to see the kinship between accessions using the NTSYS 2.11a program. Based on the identification results, there are eight accessions of Arabica coffee with three different fruit colors, namely coffee with yellow fruit (A1), red fruit (A2, A3, A4, A5, A6, A7) and orange fruit (A8). The dendogram results showed that there was a kinship between A1 with yellow fruit and A2 with red fruit at a 75% similarity level based on their morphological characters
Keyword: Accession, characterization, cluster, diversity, identification

Judul: Analisis Keragaman Morfologi Koleksi Tanaman Kopi Arabika dan Robusta Balai Penelitian Tanaman Industri dan Penyegar Sukabumi
Abstrak: Coffee (Coffea sp.) is one of the plantation plant which have become commodities that counts in national income strengthening. This study aimed to identify and analyze the morphological diversity characters of arabica and robusta coffee genotypes collection in Sukabumi Industrial and Freshener Crops Research Institute. The experiment was conducted by characterization of 11 genotypes the coffee using a descriptors list which have been modified for the coffee plants. Most of the quantitative data were analyzed by analysis of covariance and others analyzed by analysis of variance. Qualitative and some of quantitative data were analyzed by analysis of quantitative data to get a dendogram clusters. The results of the morphological identification of arabica and robusta coffee plant showed some real differences between the genotypes both the variables that can be combined or can not be combined. The results of the dissimilarity relation dendogram shows the level of the coffee plant arabica and robusta coffee kinship approximately 0.45 (45%) of the observed variables. Robusta coffee has a higher level of similarity than arabica coffee.
Keyword: Bogor Agricultural University (IPB), genotypes, dendogram, covariance, clusters, characterization

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: