Judul: Trend in Population and Production for Dairy Cattle in Indonesia 2017-2022
Abstrak: Susu sapi merupakan salah satu bahan pangan yang memiliki protein tinggi dengan cita rasa yang enak. Kebutuhan dan konsumsi susu sapi di Indonesia semakin meningkat setiap tahunnya. Dalam upaya untuk mengetahui tren peningkatan populasi, produksi dan konsumsi susu sapi, dilakukan penelitian yang bertujuan untuk mengetahui tren populasi, produksi dan konsumsi di Indonesia selama periode (2017-2022). Penelitian berdasarkan data sekunder berupa data sapi perah dari Badan Pusat Statistik (BPS) tahun 2017-2022. Data yang diambil meliputi populasi, produksi, konsumsi susu sapi di Indonesia. Data yang diperoleh dikumpulkan, ditabulasi dan dianalisis secara deskriptif. Hasil dari penelitian ini menunjukkan konsumsi susu sapi per kapita di Indonesia masih di bawah konsumsi per kapita dunia. Daya produksi nasional susu sapi masih belum cukup untuk memenuhi kebutuhan nasional. Masa pandemi berpengaruh terhadap kegiatan produksi susu sapi., Cow's milk is one of the foodstuffs that has high protein with good taste. The need for and consumption of cow's milk in Indonesia is increasing every year. In an effort to find out the trend of increasing population, production and consumption of cow's milk, a study was conducted which aimed to determine trends in population, production and consumption in Indonesia during the period (2017-2022). The research is based on secondary data in the form of data on dairy cows from the Central Bureau of Statistics (BPS) for 2017-2022. The data taken includes population, production, consumption of cow's milk in Indonesia. The data obtained were collected, tabulated and analyzed in a quantitative descriptive manner. The results of this study indicate that per capita consumption of cow's milk in Indonesia is still below world per capita consumption. The national production capacity of cow's milk is still not sufficient to meet national needs. The pandemic period affected cow's milk production activities.
Keyword: consumption, dairy cattle, population, production, trends

Judul: Analisis Produksi Susu dalam Upaya Mencapai Kemandirian Susu Nasional 2025
Abstrak: Seiring dengan meningkatnya jumlah penduduk Indonesia dan kesadaran masyarakat dalam mengonsumsi makanan serta minuman sehat, permintaan susu segar domestik diperkirakan akan terus mengalami peningkatan. Hingga tahun 2020 tercatat produksi susu segar produksi domestik hanya mampu memenuhi 23% dari total kebutuhan nasional, sehingga 77% lainnya harus dipenuhi melalui impor, dengan defisit produksi sebesar 3,4 juta ton. Sementara pemerintah memiliki target kemandirian susu nasional sebesar 60% pada tahun 2025. Prediksi pencapaian target tersebut menjadi tujuan dari penelitian ini, dengan menggunakan model ARIMA yang berbasis data time series dari tahun 1990 hingga tahun 2020. Lebih lanjut, metode regresi linear berganda digunakan untuk menganalisis faktor-faktor yang memengaruhi produksi susu, dengan berbasis data time series tahun 2000 hingga tahun 2020. Hasil peramalan menunjukkan produksi susu nasional tahun 2025 hanya mampu memenuhi 18,94% dari total kebutuhan nasional, sehingga target yang dicanangkan pemerintah belum dapat tercapai. Faktor-faktor yang secara positif dan signifikan memengaruhi produksi susu domestik adalah populasi sapi perah, harga susu, dan jumlah perusahaan sapi perah., Due to the increasing population and the awareness to consume healthy food and drinks, domestic demand of fresh milk is expected to increase steadily. However, domestic fresh milk production has only fulfilled 23% of national demands since 2020 and attained 77% of it through importation. It means that this commodity has had 3,4 million tons deficit. Nevertheless, the government of Indonesia has 60 % of milk production independences target in 2025. Predicting the target is te purpose of this study which applied the ARIMA model using time series data from 1990 to 2020. Furthermore, multiple regression model was used to analyze the factors affecting milk production, based on time series data from 2000 to 2021. The result showed that the national milk production could only fulfilled 18,94% of total demands, which impacted the unachievable national milk independences target. In addition, the multiple regression showed that the dairy cow’s population, milk price, and the dairy cow’s companies could effect milk production positively and significantly.
Keyword: Consumption, National milk independences, Production

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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