Judul: The Factors that Influence Millennial Consumer Decisions in Buying Fresh Oranges during the Covid-19 Pandemic
Abstrak: Kondisi pandemi Covid-19 menyebabkan tingkat partisipasi konsumsi jeruk oleh rumah tangga tertinggi namun besarnya konsumsi jeruk lebih rendah daripada tahun sebelumnya. Generasi milenial memiliki peluang berkontribusi terhadap konsumsi jeruk tersebut. Penelitian ini bertujuan untuk menganalisis karakteristik konsumen jeruk milenial dan nonmilenial, proses keputusan pembeliannya, dan faktor-faktor yang memengaruhi keputusan konsumen milenial membeli jeruk segar kembali di masa pandemi Covid-19. Data dikumpulkan dengan metode purposive sampling dan quota sampling maka diperoleh 267 responden. Metode analisis yang digunakan yaitu analisis dekriptif, uji chi square, dan uji regresi logistik. Hasil penelitian menunjukkan karakteristik dan keputusan konsumen milenial dan nonmilenial membeli jeruk segar di masa pandemi Covid-19 hampir tidak ada perbedaan karena generasi nonmilenial sebagian besar adalah generasi Z yang tahun kelahirannya dekat dengan generasi milenial. Faktor-faktor yang memengaruhi konsumen milenial membeli jeruk segar kembali di masa pandemi Covid-19 yaitu motif membeli jeruk dan sikap terhadap jeruk segar., The Covid-19 pandemic condition caused the orange consumption participation rate by households become the highest, but the oranges consumption was lower than the previous year. The millennial generation has the opportunity to contribute the oranges consumption. This study aims to analyze the characteristics of millennial and nonmillennial oranges consumers, their purchasing decision processes, and the factors that influence millennial consumers to repurchase fresh oranges during the Covid-19 pandemic. Data were collected by purposive sampling and quota sampling methods, so that 267 respondents were obtained. The analytical method used are descriptive analysis, chi-square test, and logistic regression test. The results of the study show that the characteristics and decisions of millennial and nonmillennial consumers purchase fresh oranges during the Covid-19 pandemic are almost undifferent because the nonmillennial generation is mostly generation Z whose birth year is close with millennial generation. The factors that influence millennial consumers repurchase fresh oranges during pandemic are the motive for buying oranges and attitudes towards fresh oranges.
Keyword: Covid-19, Millennial Generation, Fresh Oranges, Purchasing Decisions, Logistic Regression

Judul: Faktor-Faktor yang Memengaruhi Konsumen Dalam Keputusan Pembelian Jeruk Mandarin
Abstrak: Jeruk lokal tidak kalah kualitasnya dengan jeruk impor, namun Indonesia masih mengimpor jeruk. Tujuan dari penelitian ini, yaitu (1) karakteristik konsumen jeruk mandarin, (2) proses pengambilan keputusan pembelian, dan (3) faktor yang memengaruhi keputusan konsumen dalam pembelian. Data yang digunakan adalah data primer dan sekunder dengan teknik volunteer sampling. Pengolahan data dilakukan secara kuantitatif dengan analisis deskriptif dan analisis faktor. Mayoritas responden merupakan laki-laki, berusia lebih dari 45 tahun. Pendidikan terakhir S1, pekerjaan pegawai swasta. Tujuan konsumen dalam membeli jeruk mandarin, yaitu sebagai makanan pencuci mulut. Tidak mencari informasi terlebih dahulu sebelum membeli. Masih akan membeli jeruk selain mandarin ketika sedang tidak tersedia. Tidak mau membeli jeruk mandarin jika harganya naik. Merasa puas terhadap warna dan rasa, serta harga yang ditawarkan sesuai dengan kualitas yang didapatkan. Keputusan konsumen dalam membeli jeruk mandarin dipengaruhi oleh delapan faktor utama, yaitu : 1) pengaruh lingkungan, 2) gengsi, 3) pengaruh dari keluarga, 4) preferensi pembelian di pasar tradisional, 5) preferensi pembelian di supermarket, 6) kebiasaan, 7) karakteristik jeruk mandarin, dan 8) pengaruh informasi., Local oranges are not inferior in quality to imported oranges, but Indonesia still imports oranges. The aims of this study are (1) the characteristics of mandarin orange consumers, (2) the purchasing decision making process, and (3) the factors that influence consumer purchasing decisions. The data used are primary and secondary data with voluntary sampling techniques. Data processing was carried out quantitatively with descriptive analysis and factor analysis. The majority of respondents are male, aged >45 years. Bachelor's degree, private employee job. Consumers buy mandarin oranges to consume it as a dessert. Customers not looking for further information. Will still buy another oranges when mandarin is not available. Won’t buy mandarin oranges if the price increasing. Satisfied with the color and taste, also the price offered according to the quality obtained. Consumer decisions in buying mandarin oranges are influenced by eight main factors, namely: environmental influences, prestige, family influences, purchasing preferences in traditional markets, purchasing preferences in supermarkets, habits, characteristics of mandarin oranges, and the influence of information.
Keyword: buying decision, consumer behaviour, mandarin orange

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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