Judul: Shallot Agribusiness Development Strategy as a  Leading Commodity in Boyolali Regency
Abstrak: Kabupaten Boyolali merupakan daerah sentra bawang merah dengan produktivitas yang berfluktuatif, salah satu penyebabnya adalah belum adanya produsen benih bersertifikat di daerah tersebut. Penelitian ini bertujuan mengidentifikasi faktor internal dan eksternal yang memengaruhi agribisnis bawang merah, serta merumuskan dan menganalisis prioritas alternatif strateginya. Pengambilan data melalui studi literatur, observasi lapangan, FGD, dan pengisian kuesioner oleh petani, usaha pengolahan, pemasaran, BPP Kecamatan Cepogo, DISPERTAN Kabupaten Boyolali, serta akademisi. Analisis menggunakan metode A’WOT (AHP-SWOT). Berdasarkan hasil penelitian, kekuatan utama adalah lahan budidaya di dataran tinggi cocok untuk varietas batu ijo dengan umbi besar dan cerah, sedangkan kelemahan utama adalah produktivitas berfluktuatif. Peluang utama adalah permintaan tinggi, sedangkan yang menjadi ancaman utama adalah ketidakpastian iklim. Prioritas strategi pengembangan agribisnis bawang merah adala memperkuat penerapan GAP, peningkatan produksi dengan mengoptimalkan pemanfaatan sumber daya, pengembangan usaha perbenihan yang bersertifikat, meningkatkan pengawasan terhadap persediaan pasokan, dan pengembangan produk olahan bawang merah., Boyolali Regency is a shallot center area with fluctuating productivity, one of the reasons is that there are no certified seed producers in the area. This research aims to identify internal and external factors that influence the shallot agribusiness, as well as formulate and analyze strategi alternative priorities. Data collection was carried out through literature studies, field observations, FGD, and surveys with farmers, processing businesses, marketing, BPP of Cepogo, DISPERTAN of Boyolali, and academics. Analysis uses the A'WOT (AHP-SWOT) method. Based on the research results, the main strength is that cultivation land in the highlands is suitable for the green stone variety with large and bright tubers, while the main weakness is fluctuating productivity. The main opportunity is high demand, while the main threat is climate uncertainty. The priority strategy for developing shallot agribusiness is strengthening the implementation of GAP, increasing production by optimizing resource utilization, developing certified seed businesses, increasing control over supplies, and developing processed shallot products.
Keyword: A’WOT, shallot, external factors, internal factors, strategic priorities

Judul: Consistency and Shrink-Swell Soils in Shallot Field, Brebes Regency, Central Java
Abstrak: Bawang merah merupakan salah satu komoditas yang sangat dibutuhkan dalam kehidupan sehari-hari. Sentra produsen bawang merah terbesar di Indonesia adalah Kabupaten Brebes. Namun pada kenyataannya produktivitas bawang merah di Kabupaten Brebes mengalami penurunan. Salah satu upaya untuk meningkatkan produktivitas bawang merah yaitu dengan melakukan pengolahan tanah yang baik, misalnya dengan mengkaji konsistensi tanah di lahan tersebut. Kemampuan mengembang dan mengerut tanah yang tinggi dapat beresiko terhadap pertumbuhan umbi bawang merah. Resiko tersebut dapat diminimalisir dengan cara memperhatikan nilai COLE (Coeficient Of Linear Extensibility) yang merupakan indikator dalam penetapan sifat mengembang dan mengerut tanah. Penelitian ini bertujuan menganalisis konsistensi dan nilai COLE serta kaitannya dengan sifat fisik dan kimia tanah pada lahan bawang merah di Kabupaten Brebes, Jawa Tengah. Hasil penelitian menunjukkan bahwa Konsistensi dan Nilai COLE tanah berbeda antar jenis tanah. Indeks plastisitas, jangka olah, dan nilai COLE memiliki korelasi terhadap kadar klei dan bahan organik. Ketiga jenis tanah memiliki Indeks plastisitas yang tinggi, jangka olah yang sempit, dan nilai COLE yang baik. Hal ini menunjukkan kualitas tanah pada lahan ini masih perlu diperbaiki untuk memperoleh kondisi yang lebih baik bagi pertumbuhan bawang merah., Shallots are one of the commodities needed in everyday life. The largest shallot producing center in Indonesia is Brebes Regency. But in reality, shallot productivity in Brebes Regency has decreased. One of the efforts to increase shallot productivity is by doing good tillage, for example by assessing the consistency of the soil. The high ability of soil to swell and shrink can be a risk to the growth of shallot bulbs. This risk can be minimized by paying attention to the COLE (Coeficient Of Linear Extensibility) value which is an indicator in determining the soil swelling and shrinking. This study aims to analyze the consistency and value of shrink-swell soil and its relation to the soil physical and chemical properties on shallot fields in Brebes Regency, Central Java. The results showed that soil consistency and shrink-swell value were different among soil types. Plasticity index, tillage period, and shrink-swell value have a correlation with clay and organic matter content. All three soil types have high plasticity index, narrow tillage period, and good shrink-swell value. This shows that the quality of the soil on this land still needs to be improved to obtain better conditions for the growth of shallots.
Keyword: gleisol, cambisol, mediteran, productivity

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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