Judul: The Influence of Psychological Factors on the Decision to Purchase Organic Vegetables and Fruits through E-commerce during the Covid-19 Pandemic
Abstrak: Perkembangan internet yang semakin pesat dimanfaatkan masyarakat untuk melakukan transaksi bisnis secara daring sehingga muncul adanya e-commerce. Situasi Pandemi Covid-19 menyebabkan peningkatan pengguna e-commerce sebagai alat untuk berbelanja. Sayur dan buah organik sebagai alternatif piihan pangan sehat mulai dicari di masa pandemi Covid-19. Kebutuhan ini dapat dipenuhi melalui pemanfaatan e-commerce sebagai media transaksi jual beli saat pandemi Covid-19. Penelitian ini bertujuan untuk menganalisis pengaruh faktor psikologis kepercayaan, keamanan, dan kemudahan terhadap keputusan pembelian sayur dan buah organik melalui e-commerce. Penelitian ini menggunakan data primer dari 200 responden di wilayah Jabodetabek melalui kuesioner secara daring. Metode yang digunakan dalam penelitian ini adalah analisis deskriptif dan analisis SEM-PLS. Hasil penelitian menunjukkan bahwa variabel kepercayaan, keamanan, kemudahan berpengaruh positif dan signifikan terhadap keputusan pembelian online. Perusahaan e-commerce perlu memperhatikan variabel yang berpengaruh signifikan sebagai bahan pertimbangan dalam memasarkan produknya., The community is using the rapid development of the internet to conduct online business transactions, resulting in the emergence of e-commerce. The Covid19 pandemic situation has led to an increase in e commerce users as a means of shopping. Organic vegetables and fruits began to be sought as an alternative to healthy food choices during the Covid-19 pandemic. This demand can be fulfilled using e commerce as media for buying and selling transactions during the Covid19 pandemic. This study analyses the influence of psychological factors of trust, safety, and convenience on purchasing decisions for organic vegetables and fruits through e-commerce. This study used primary data from 200 respondents in the Jabodetabek area through an online questionnaire. The method used in this research is descriptive analysis and SEM-PLS analysis. The results showed that the variables of trust, security, convenience have a positive and significant effect on online purchasing decisions. E-commerce companies need to put emphasize on variables that have a significant effect on marketing their products.
Keyword: Covid-19, E-commerce, Online 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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