Judul: Determinants of Consumer Willingness to Pay for Organic Mustard in Surabaya
Abstrak: Pertanian organik merupakan suatu sistem produksi pertanian yang holistik dan terpadu, yang mengoptimalkan kesehatan dan produktivitas agroekosistem secara alami sehingga mampu menghasilkan pangan dan serat yang cukup, berkualitas, dan berkelanjutan. Perkembangan akan luasan pertanian organik yang terus terjadi mengindikasikan bahwa pertanian organik memiliki potensi untuk dikembangkan di Indonesia. Di samping itu, dengan meningkatnya luasan pertanian organik tersebut maka ketersediaan produk pertanian organik juga diharapkan semakin meningkat. Saat ini sistem pertanian organik di Indonesia telah diterapkan pada produksi sayur-sayuran termasuk sawi organik. Saat ini pasar produk organik Indonesia sudah berkembang di kota-kota besar seperti Jakarta dan Surabaya. Hal ini merupakan respon terhadap meningkatnya minat konsumen perkotaan terhadap produk organik termasuk sayuran segar. Penelitian ini bertujuan menganalisis kesediaan membayar (willingness to pay, WTP) konsumen terhadap sawi organik dan faktor-faktor yang mempengaruhi WTP konsumen tersebut. Penelitian ini menggunakan data primer hasil survei 150 konsumen pasar modern di Surabaya pada bulan Mei-Juni 2023. Penentuan 150 responden tersebut menggunakan metode accidental sampling dengan kriteria yaitu konsumen sayuran daun berusia 17 tahun ke atas dan berdomisili di Kota Surabaya. Data dianalisis menggunakan discrete choice experiment (DCE) dan analisis regresi logit. DCE yang terdiri dari delapan choice set digunakan untuk menganalisis nilai kesediaan konsumen untuk membayar sawi organik. Regresi logit digunakan untuk menganalisis faktor-faktor yang memengaruhi kesediaan untuk membayar sayuran sawi hijau organik di pasar modern di Kota Surabaya. Hasil penelitian menunjukkan bahwa konsumen bersedia membayar sawi orgnaik dengan harga premium berkisar hingga Rp. 2393,2, Rp. 3517 dan Rp. 5622,6 per ikat untuk masing-masing sawi organik yang memiliki mutu lebih baik berdasarkan sifat daun hijau mulus segar, memiliki merek, dan memiliki lebel organik. Hasil penelitian juga menunjukkan bahwa faktor-faktor yang berpengaruh signifikan terhadap WTP konsumen akan sawi organik di Kota Surabaya adalah usia, tingkat pendidikan, dan pendapatan keluarga. Penelitian ini memberikan informasi yang berguna baik bagi produsen maupun pemasar sayuran organik untuk membantu merancang strategi produksi dan pemasaran sayuran organik., Organic farming is a holistic and integrated agricultural production system, which optimizes the health and productivity of agroecosystems naturally so that it can produce sufficient, high-quality, and sustainable food and fiber. The ongoing development of the extent of organic farming indicates that organic farming has the potential to be developed in Indonesia. Apart from that, with the increase in the area of organic farming, the availability of organic agricultural products is also expected to increase. Currently, organic farming systems have been applied to vegetables, including organic mustard greens. Currently, markets for Indonesian organic products are developing in big cities such as Jakarta and Surabaya. This is a response to the increasing interest of urban consumers in organic products including fresh vegetables. This research aims to examine the willingness to pay (WTP) of organic mustard greens consumers and the factors that influence these consumers' WTP. This research uses primary data from a modern market consumer survey of 150 people conducted in Surabaya during May-June 2023. The sampling method used was accidental. The consumers who were used as respondents in this research were leaf vegetable consumers aged 17 years and over in the Surabaya City area. The data used are discrete
Keyword: discrete choice experiment, sawi, sayuran organik, willingness to pay

Judul: Analisis Kesediaan Membayar (Willingness To Pay) Sayuran Organik dan Faktor - Faktor yang Mempengaruhinya (Studi Kasus Kota Bogor, Jawa Barat)
Abstrak: The era of modernization and the increasing in GDP per capita have changed the consumer behavior of Indonesian people. Indonesian people realize the importance of healthy living by consuming organic vegetables. The increasing production cost as a result of improving product quality induced the selling price of organic vegetables in market. This research aims to identify customer characteristics who made a purchase on organic vegetables by using descriptive analysis, to estimate consumer willingness to pay (WTP) using Contingent Valuation Method (CVM) and to analyze factors that influence the Willingness To Pay using Structural Equation Modeling (SEM) with LISREL. The result of this research showed the mean of maximum WTP for cabbage commodity is Rp 18.738; lettuce is Rp 30.048; broccoli is Rp 40.250; chinese cabbage (bok choy) is Rp 24.368 and carrot is Rp 19.820. The attitude and obstacle effect on WTP is significant, while the effect of SES is not significant.
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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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