Judul: Mencari Kunci Produktivitas Ubi Jalar Cilembu dengan Membandingkan Aspek Teknik Budidaya, Aspek Sifat Tanah dan Faktor Lingkungan. Studi Kasus : Desa Cilembu Sumedang dan Desa Cilubang Mekar Bogor.
Abstrak: Cilembu has high economic value as a distinctive taste, sweet as honey and sticky, chewy meat and interesting so that it is favored by agricultural businesses and consumers. For land use and also as well as the development of Cilembu maintenance, preservation is needed for Cilembu because of several observations indicate that Cilembu does not grow well in all regions. The purpose of this research is to look for the key productivity of Cilembu by comparing aspects of cultivation techniques, soil characteristics, and environmental factors in two different places Cilembu village in Sumedang and Cilubang Mekar village in Bogor so that it can produce large tubers and sweet taste. The location of this study includes two different locations namely in Cilubang Mekar RW 08 Kelurahan Situgede Kecamatan Bogor Barat and in Sawah Lega Cilembu village Kecamatan Pamulihan Sumedang . The observation result of the three observed aspects shows that for the cultivation aspects of both places did not show significant differences, both places make the process of reversal of the stem, the bulb in Bogor is smaller in size, while the yield on Cilembu is large. At the time of post-harvest in Bogor ripening process is not done, the result of tuber is marketed, while in Cilembu, when tubers are harvested there is a process of curing, it makes tubers become sweet due to change the starch into sugar. Further aspects of soil properties included soil color and texture shows that there was not significant different, whereas for chemical analysis of organic C and K there was a little difference. Analytical data the shows K (0,153me/100g) in Cilubang Mekar and those were classified as in the Cilembu village (0,267me/100g) whereas the C-organic in Cilubang Mekar was 1,45% low and in the Cilembu Village was 2,37%. The last aspect of environmental factors showed was not significant different in temperature. Cilembu Sumedang has 17-24oC with a difference >5°, while the temperature Cilubang Mekar was 23-28oC with the difference <5o. Cilembu places in the valley and closes to mountain with different altitude > 500 m. Key Cilembu productivity growth obtained for the time being the process of curing and temperature differences that cause the bulbs are large and have a sweet taste.
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Judul: Analisis Daya Saing Ubi Jalar Cilembu di Kabupaten Sumedang Jawa Barat
Abstrak: Dalam struktur perekonomian Indonesia, sektor pertanian sangat berperan penting dalam menunjang pertumbuhan ekonomi nasional. Tetapi sektor ersebut tidak dipersiapkan untuk bersaing dengan negara lain. Berdasarkan data dari global competitiveness report Tahun 2010-2011, daya saing global Indonesia berada pada urutan 44 tetapi Indonesia masih berada pada tahap factor driven ke efficiency driven. Hal tersebut mengindikasikan bahwa Indonesia belum bisa mencapai efisiensi, terutama pada produk-produk pertanian seperti ubi jalar yang masih banyak diekspor dalam keadaan segar sehingga menyebabkan harga jual menjadi rendah. Indonesia berpotensi untuk budidaya ubi jalar dikarenakan sumber daya alam yang melimpah yang bisa menghasilkan ubi berkualitas baik. Pada Tahun 2009, Jawa Barat merupakan sentra produksi dan memiliki dua Kabupaten yang bisa menghasilkan ubi yang dipasarkan ke luar negeri. Ubi Cilembu merupakan komoditi unggulan yang telah diekspor ke Malaysia, Singapura, Jepang dan Hongkong. Berdasarkan sembilan indikator utama daya saing daerah, pengusahaan ubi Cilembu memiliki lima kendala dan empat peluang. Kendala tersebut diantaranya teknologi, kebijakan pemerintah daerah, perekonomian daerah, manajemen, dan sistem keuangan sedangkan peluang yang ada adalah pasar yang terbuka lebar (ekspor), sumberdaya alam, sumberdaya manusia, dan kelembagaan. Berkaitan dengan peluang dan kendala, maka penelitian ini bertujuan untuk menganalisis daya saing (keunggulan kompetitif dan komparatif) dan pengaruh kebijakan pemerintah terhadap pengusahaan ubi Cilembu di Kabupaten Sumedang. Penelitian ini dilakukan di Desa Cilembu (Kecamatan Tanjungsari) dan Desa Nagarawangi (Kecamatan Rancakalong) Kabupaten Sumedang, Propinsi Jawa Barat. Pemilihan lokasi dilakukan dengan secara sengaja (purposive sampling) dan pengambilan data dilaksanakan pada bulan Mei sampai Juni 2011. Metode pengambilan responden dilakukan secara sengaja sebanyak 50 orang dan memenuhi kriteria, memiliki lahan sendiri, melakukan usahatani ubi lebih dari lima tahun, dan merupakan anggota kelompok tani. Terdapat persamaan dan perbedaan dengan penelitian sebelumnya yaitu menggunakan alat analisis yang sama yaitu Policy Analysis Matrix (PAM) dan analisis sensitivitas. Sedangkan perbedaannya adalah produk, tujuan ekspor dan lembaga pemasaran.
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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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