Judul: Development of Group Consultation Features and Recording of the Performance of IPB Experts at IPB Digitani with the Prototyping Method
Abstrak: Pertanian merupakan sektor penghasil kebutuhan primer dan penyerap tenaga kerja yang cukup banyak di Indonesia. Namun, pada kenyataannya sebagian besar petani di Indonesia berusia di atas 40 tahun dan 70% diantaranya berpendidikan sekolah dasar yang mengakibatkan terbatasnya pengetahuan pertanian dan akses kepada inovasi-inovasi pertanian. Aplikasi IPB Digital Tani (Digitani) hadir sebagai penyedia informasi pertanian bagi para petani dan sarana komunikasi antara pakar-pakar IPB dengan para petani diawasi dan dikelola oleh Tani Center, sebagai LPPM IPB. Digitani IPB dikembangkan oleh DSITD IPB. Fitur konsultasi pada IPB Digitani yang ada sekarang hanya antara pakar dan petani saja, sehingga untuk pertanyaan seorang petani yang sudah selesai terjawab oleh seorang pakar, petani lain tidak langsung mendapat jawabannya. Tani Center sebagai pengawas IPB Digitani juga belum mempunyai menu khusus sebagai administrator Digitani. Maka, dikembangkanlah fitur konsultasi yang juga bisa sebagai chatting antar user dengan lingkup pribadi dan grup, dikembangkan pula fitur pencatatan kinerja pengabdian pakar IPB serta menu khusus untuk administrator. Chatting dan konsultasi dikembangkan dengan teknologi Socket.io untuk mengirim pesan berupa teks dan gambar, sementara fitur-fitur pendukung chatting, pengabdian, dan menu khusus administrator dikembangkan dengan HTTP request melalui komunikasi REST API., Agriculture is a sector that produces primary needs and absorbs quite a lot of labor in Indonesia. However, the majority of Indonesian farmers are over 40 years old and 70% of them only have primary school education resulting in limited agricultural knowledge and access to agricultural innovations. The IPB Digital Tani application is present as a provider of agricultural information for farmers and a means of communication between IPB experts and farmers, supervised and managed by the Tani Center, as LPPM IPB. Digitani was developed by DSITD IPB. The current consultation feature is only between experts and farmers, so that for questions that have already been answered, other farmers do not get answers right away. Tani Center as the supervisor of IPB Digitani does not yet have a special menu as administrator of Digitani. Then a consultation feature was developed which can also be used as a chat between users with development scope of personal and group chat, a feature for recording the performance of IPB expert dedication and a special menu for administrator was developed too. Chats and consultations were developed with Socket.io technology to send messages in the form of text and images, while support features for chat, dedication, and administrator menus were developed with HTTP requests throughout the REST API communication.
Keyword: consultation, dedication, Digitani, REST API, Socket.io

Judul: -end Development of Consultation and Financial Management Features in Digital Tani Mobile Application
Abstrak: Aplikasi IPB Digitani merupakan aplikasi mobile android yang menyediakan layanan tata kelola pertanian. Aplikasi ini memiliki fitur seperti layanan informasi harga komoditas pertanian, materi pertanian dalam bentuk fail dokumen dan video, serta layanan penyampaian aspirasi ke pemerintah. Fitur-fitur ini merupakan penggabungan hasil penelitian yang dikembangkan berdasarkan roadmap penelitian e-government di bidang pertanian dari tahun 2016-2020. Namun, belum terdapat fitur konsultasi dan manajemen keuangan pada aplikasi IPB Digitani. Pada penelitian ini akan dilakukan pengembangan back-end fitur konsultasi dan manajemen keuangan menggunakan metode prototyping untuk aplikasi IPB Digitani. Tambahan modul back-end ini dikembangkan dengan menggunakan arsitektur REST API dan MongoDB sebagai basis data., The IPB Digitani application is an android mobile application that provides agricultural governance services. This application has features such as agricultural commodity price information service, agricultural materials in the form of document and video files, and service to convey aspirations to the government. These features are from various research based on the e-government research roadmap in agriculture from 2016-2020. However, there is no financial management and consultation features in the IPB Digitani application. This research will conduct the back-end module development of consultation and financial management features using prototyping method for the Digital IPB application. This additional back-end module developed using the REST API architecture and MongoDB as the database.
Keyword: REST API, socket.io, back-end, node.js

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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