Judul: Satisfaction Levels of IPB Undergraduate Students towards Online Learning Services during the Pandemic Covid-19
Abstrak: Pandemi Covid-19 menyebabkan proses belajar mengajar di seluruh lembaga pendidikan harus diubah metodenya menjadi daring. Institut Pertanian Bogor (IPB) merupakan salah satu universitas yang ikut menerapkan pembelajaran daring terhitung dari bulan Maret 2020. Penelitian ini dilakukan dengan tujuan untuk menganalisis tingkat kepuasan mahasiswa S-1 IPB terhadap layanan pembelajaran daring selama pandemi Covid-19. Responden pada penelitian ini dipilih dengan menggunakan teknik voluntary sampling dengan jumlah responden sebanyak 255 responden. Data dikumpulkan melalui kuesioner online menggunakan google form. Data yang diperoleh diolah menggunakan microsoft excel, SPSS versi 25, dan SMART-PLS 3. Hasil analisis uji pengaruh menunjukkan kualitas layanan berpengaruh positif signifikan terhadap kepuasan konsumen, dan kepuasan konsumen berpengaruh positif signifikan terhadap net benefit. Saran yang bisa diberikan adalah IPB, dosen, hingga tendik departemen perlu mempertahankan dan meningkatkan kualitas pelayanan pembelajaran daring dari berbagai aspek., The Covid-19 pandemic has led to changes to the learning system online in all educational institutions. IPB University is one of the universities that implements online learning starting in March 2020. This research was conducted with the aim of analyze the level of satisfaction of IPB undergraduate students with online learning services during the Pandemic Covid-19. Respondents in this research were selected by voluntary sampling technique with 255 respondents. Data was collected through an online questionnaire using google form. The data obtained were processed using Microsoft Excel, SPSS version 25, and SMART-PLS 3. The results of the test analysis show that service quality has a significant positive effect on customer satisfaction, and also show that consumer satisfaction has a significant positive effect on the net benefit. Suggestions that can be given are that IPB, lecturers, and departments need to maintain and improve the quality of online learning services from various aspects.
Keyword: Kualitas layanan, Pembelajaran daring, Kepuasan, E-learning, satisfaction, service quality

Judul: Factors Affecting Bogor Agricultural  University Students' Academic Achievement in Online and Offline Learning
Abstrak: Meski pandemi Covid-19 telah berlalu, penerapan pembelajaran daring sebagian masih terus berlanjut. Alasan utamanya adalah, sistem ini memiliki fleksibilitas yang tinggi serta infrastruktur penunjangnya semakin baik, sehingga sistem perkuliahan hibrid menjadi suatu pilihan. Keberhasilan aktivitas perkuliahan tidak saja ditentukan oleh sistem perkuliahan yang digunakan namun terdapat faktor lainnya, baik dari sisi mahasiswa maupun institusi pendidikan, seperti faktor inteligensi, motivasi, kebiasaan, emosi, lingkungan belajar, lingkungan sosial, sarana kampus, dan sarana daring. Penelitian ini ditujukan untuk menguji pengaruh faktor-faktor tersebut terhadap prestasi belajar. Penelitian ini melibatkan 170 mahasiswa S1 Institut Pertanian Bogor yang mengikuti kuliah daring dan luring. Pengumpulan data dilakukan melalui voluntary sampling techniques, dimana kuesioner disampaikan melalui media sosial kepada target responden. Structural Equation Modeling digunakan untuk menduga koefisien model yang menjelaskan hubungan kausalitas antara prestasi belajar dengan faktor-faktor yang memengaruhinya. Hasil penelitian menunjukan, inteligensi mahasiswa menjadi faktor yang paling berpengaruh terhadap prestasi diikuti faktor lingkungan sosial., Although the COVID-19 pandemic has passed, the implementation of online learning continues partially. The main reasons are the high flexibility of this system and the improvement of supporting infrastructure, making the hybrid learning system a viable option. The success of lecture activities is not only determined by the lecture system used but also by other factors from both students and educational institutions, such as intelligence, motivation, habits, emotions, learning environment, social environment, campus facilities, and online facilities. This study aims to examine the influence of these factors on academic achievement. The study involved 170 undergraduate students from Bogor Agricultural University who participated in both online and offline learning. Data collection was conducted through voluntary sampling techniques, where questionnaires were distributed via social media to the target respondents. Structural Equation Modeling was used to estimate the model coefficients that explain the causal relationships between academic achievement and the influencing factors. The results show that student intelligence is the most influential factor on academic achievement, followed by the social environment factor.
Keyword: online learning, hasil pembelajaran, pembelajaran daring, pembelajaran efektif, prestasi mahasiswa, structural equation modeling, learning effectiveness, learning outcomes, student achievement

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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