Judul: Fruits and Vegetable Purchase Intentions and Decisions through E-Commerce: Development of Theory of Planned Behavior
Abstrak: Tren pemanfaatan akses internet di Indonesia mengalami peningkatan yang signifikan, termasuk dalam perdagangan elektronik. Pandemi COVID-19 di Indonesia berdampak pada perubahan perilaku konsumen dalam berbelanja dari konvensional menjadi online yang terus meningkat. Perubahan perilaku tersebut untuk mengurangi aktivitas fisik di luar rumah dan memudahkan konsumen dalam belanja. Penelitian ini bertujuan untuk menganalisis pengaruh sikap, norma subjektif, kontrol perilaku, kepercayaan, dan situasi pandemi COVID-19 terhadap keputusan pembelian buah dan sayur melalui e-commerce. Penelitian ini menggunakan data primer yang diperoleh dari 190 responden dengan metode purposive sampling. Data dianalisis menggunakan metode analisis deskriptif dan Structural Equation Model-Partial Least Square (SEM-PLS). Hasil penelitian menunjukkan bahwa variabel kontrol perilaku dan situasi pandemi COVID-19 memiliki pengaruh yang positif dan signifikan terhadap niat dan keputusan pembelian buah dan sayur melalui e-commerce saat pandemi COVID-19., The trend of internet access in Indonesia has experienced a significant increase, including in electronic commerce. The COVID-19 pandemic in Indonesia has an impact on changing consumer behavior in shopping from conventional to online which continues to increase. These behavioral changes can reduce physical activity outside the home and make it easier for consumers to shop. This study aims to analyze the effect of attitudes, subjective norms, behavioral control, beliefs, and the COVID-19 pandemic situation on fruit and vegetable purchasing decisions trough e-commerce. This study uses primary data obtained from 190 respondents with a purposive sampling method. Data were analyzed using descriptive analysis methods and Structural Equation Model-Partial Least Square (SEM-PLS). The results showed that behavioral control variable and the COVID-19 pandemic situation had a positive and significant influence on intentions and decisions to purchase fruit and vegetables through e-commerce during the COVID-19 pandemic.
Keyword: COVID-19, e-commerce, purchasing decision, SEM-PLS

Judul: The Effect of New Normal Situation on Intention and Behavior to Purchase Vegetables Through Agricultural E-commerce
Abstrak: Tren peningkatan penetrasi internet di Indonesia dimanfaatkan masyarakat untuk melakukan transaksi bisnis secara daring melalui e-commerce pertanian. Situasi new normal di Indonesia tetap menjadi faktor penting keputusan pembelian sayuran secara online. E-commerce pertanian digunakan masyarakat untuk memenuhi kebutuhan sehari-hari dalam membeli produk sayuran. Penelitian ini bertujuan untuk menganalisis sikap, norma subjektif, kontrol perilaku, dan situasi new normal terhadap niat dan perilaku pembelian sayuran melalui e-commerce pertanian. Penelitian ini menggunakan data primer melalui penyebaran kuesioner secara daring dengan jumlah 130 responden. Metode yang digunakan dalam penelitian ini adalah analisis deskriptif dan Structural Equation Model-Partial Least Square (SEM-PLS). Hasil penelitian ini menunjukkan bahwa konsumen sayuran e-commerce pertanian adalah perempuan muda yang mandiri dan menyukai belanja sayuran di Sayurbox, HappyFresh, Segari, TukangSayur.id, dan Astro. Variabel sikap dan situasi berpengaruh signifikan terhadap niat pembelian sayuran dan kontrol perilaku berpengaruh signifikan secara langsung terhadap perilaku pembelian sayuran melalui e-commerce pertanian., An increasing trend of increasing internet penetration which is used by the public to conduct business transaction through agricultural e-commerce. New normal situation in Indonesia remains an important factor in online purchasing decisions for vegetables. Agricultural e-commerce is used by the community to provide their daily needs in buying vegetable products. This study aims to analyze planned behavior attitudes, subjective norms, behavioral control, and situation on vegetable purchase intentions and behavior through agricultural e-commerce. This study uses primary data through online questionnaires with a total of 130 respondents. The method used in this research is descriptive analysis and Structural Equation Model-Partial Least Square (SEM-PLS). The results of this study indicate that consumers of vegetables through agricultural e-commerce is an independent young woman who loves shopping for vegetables at Sayurbox, HappyFresh, Segari, TukangSayur.id, and Astro. Attitude and situation variables have a significant effect on the intention to buy vegetables and behavioral control has a significant direct effect on the decision to buy vegetables through agricultural e-commerce.
Keyword: e-commerce, perilaku pembelian, SEM-PLS

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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