Judul: A portable system to record Apis cerana Bee Sound in Response to the Presence of the Asian hornet Predator (Vespa velutina) Based on Raspberry Pi
Abstrak: Pemantauan sinyal yang dihasilkan coloni lebah ini sangat penting guna mencegah adanya peristiwa Colony Collapse Disorder (CCD). Tujuan penelitian ini adalah membuat suatu instrumen untuk mendeteksi kehadiran predator Asian hornet (Vespa velutina) dengan mengukur suara lebah A. cerana dan mengubahnya menjadi nilai frekuensi yang spesifik. Sistem manajemen pengelolaan data masih bersifat data logger. Instrument ini dapat memantau dan merekam sinyal yang dihasilkan oleh lebah penjaga dari jarak jauh dengan bantuan koneksi internet menggunakan aplikasi VNC Viewer. Data disimpan pada microSD dan diolah menggunakan aplikasi Raven lite 2.0. Pengambilan data dilakukan pada pukul 07.00 hingga 17.00. Jenis sinyal yang dihasilkan oleh lebah A. cerana saat terjadi serangan V. velutina dan dummy predator yaitu berupa sinyal berhenti (stop signal) dan pipa antipredator. Rata-rata frekuensi tertinggi pada jenis sinyal berhenti yaitu 17501,39 Hz dengan durasi rata-rata 174,35 ms yang terjadi pada perlakuan dummy predator. Rata-rata frekuensi tertinggi pada pipa antipredator yaitu 18333,85 Hz dengan durasi rata-rata 558,117 ms yang terjadi pada serangan V. velutina. Heatballing behavior timbul karena serangan V. velutina yang terlalu intens dan dekat dengan pintu masuk sarang., Monitoring the signal generated by the bee colony is very important to prevent Colony Collapse Disorder (CCD) events. This study aimed to develop an instrument to detect the presence of the predatory Asian hornet (Vespa velutina) by measuring the sound of the A. cerana bee and converting it into a specific frequency value. The data management system is in the form of a data logger. This instrument can monitor and record the signal generated by the guard bees remotely via an internet connection using the VNC Viewer application. The bee’s sound was recorded during the observation period from 07.00 a.m to 05.00 p.m. The signals generated by the A. cerana bee because of the attack of V. velutina and dummy predators were in the form of a stop signal and an antipredator pipe. The highest average frequency for this type of stop signal is 17501,39 Hz with an average duration of 174,35 ms, which occurs in the dummy predator treatment. The highest average frequency in the antipredator pipe was 18333,85 Hz with an average time of 558,117 ms, which happened in the attack of V. velutina. In addition, a heatballing behavior arises when the V. velutina attacks are too intense and close to the nest entrance.
Keyword: colony collapse disorder, antipredator pipe, Raspberry Pi, sound sensor, stop signal

Judul: Frequency Analysis of Honeybee (Apis cerana) Sound  Signals for Early Detection of Vespa velutina Hornet Predator Presence
Abstrak: Sistem deteksi dini kehadiran predator Tawon Vespa dapat menjadi solusi dalam melindungi koloni lebah dan membantu petani lebah dalam menghadapi ancaman predator yang merusak koloni. Penelitian ini bertujuan membangun sistem deteksi dini (early warning system) yang menginformasikan kehadiran predator Tawon Vespa velutina berdasarkan frekuensi suara spesifik yang dihasilkan lebah pekerja Apis cerana. Sistem deteksi dini yang dikembangkan menggunakan bahasa pemrograman Python dan menghasilkan Graphical User Interface (GUI) untuk mempermudah pengambilan data dari perekaman suara lebah. Dalam pengambilan data, dilakukan perlakuan pada koloni lebah dengan tiga kondisi: tanpa gangguan predator, dengan gangguan alami, dan gangguan buatan. Hasil rekaman suara menunjukkan adanya perubahan rentang frekuensi pada setiap kondisi, dengan rentang frekuensi 200-600 Hz menjadi indikator utama kehadiran predator. Sistem deteksi ini dilengkapi dengan mekanisme notifikasi melalui aplikasi Telegram, yang dapat mengirimkan pesan notifikasi berupa foto dan teks "Ada Predator Tawon Vespa!" saat frekuensi yang sesuai terdeteksi., An early detection system for the presence of the hornet predator can serve as a solution to protect bee colonies and assist beekeepers in combating the threat posed by this destructive predator. This study aims to develop an early warning system that informs the presence of Vespa velutina predators based on specific sound frequencies produced by Apis cerana worker bees. The developed early detection system utilizes Python programming language and provides a Graphical User Interface (GUI) for convenient data retrieval from bee sound recordings. During data collection, the bee colonies were subjected to three conditions: without predator disturbance, natural disturbance, and artificial disturbance. The recorded sound samples indicated changes in frequency ranges under each condition, with the frequency range of 200-600 Hz serving as the primary indicator of predator presence. The detection system is equipped with a notification mechanism through the Telegram application, capable of sending notification messages containing photos and the text "Ada Predator Tawon Vespa!" when the corresponding frequency is detected.
Keyword: frekuensi, predator tawon, sinyal suara lebah, sistem deteksi dini, sistem notifikasi

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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