Microscopic origin of the bolometric effect in graphene

While the thermoelectric and photoconduction effects are crucial in pristine and low-doped graphene, the bolometric effect is known to dominate the photoresponse in biased graphene. Here, we present a detailed microscopic investigation of the photoresponse due to the bolometric effect in graphene. Based on the semiconductor Bloch equations, we investigate the time- and momentumresolved carrier dynamics in graphene in the presence of a constant electric field under optical excitation. The magnitude of the bolometric effect is determined by the optically induced increase of temperature times the conductivity change. Investigating both factors independently, we reveal that the importance of the bolometric effect in the high-doping regime can be mostly ascribed to the latter showing a parabolic dependence on the doping

PEMANFAATAN QR-CODE VAKSIN COVID-19 UNTUK ABSENSI MENGGUNAKAN METODE EXTREME PROGRAMMING

The digital attendance system enables more efficient data processing, real-time time monitoring, and reduces human errors in the recording process. One of the schools that has developed this technology is SMK Negeri 4 Kota Sorong. This is related to the last two years, where almost everyone has been required to receive the COVID-19 vaccine for prevention and monitoring of student attendance at school. To support the monitoring of student attendance at school, a web-based COVID-19 Vaccine QR-Code utilization system is needed at SMK Negeri 4 Sorong, Southwest Papua. This student attendance system has three access levels, which are divided into admin, teachers, and parents. This research uses PHP programming language and MySQL database. The development of this system is carried out using the Extreme Programming method, which includes steps such as problem identification, data collection, applying the Extreme Programming method, and implementation. The school attendance system, which has been built with its features, has been proven to work perfectly through feature testing using black-box testing with a 100% success rate. From the results of this testing, the utilization of the COVID-19 Vaccine QR-Code can be used for attendance and departure monitoring.Sistem absensi digital memungkinkan pengolahan data yang lebih efisien, pemantauan waktu secara real-time, dan mengurangi kesalahan manusia dalam proses pencatatan. Salah satu sekolah yang di kembangkan teknologi tersebuat adalah SMK Negeri 4 Kota Sorong. Hal ini berkaitan dengan 2 tahun terakhir hampir semua orang diwajibkan menerima vaksin covid-19 dan untuk pencegahan,serta pemantauan kehadiran siswa disekolah. Untuk mendukung proses pemantuan kehadiran siswa disekolah maka diperlukan sistem pemanfaatan QR-Code Vaksin Covid-19 berbasis web di SMK Negeri 4 Sorong Papua Barat Daya. Sistem absensi siswa ini memiliki tiga akses yang terbagi menjadi admin, guru, dan orang tua. Penelitian ini menggunakan bahasa pemrograman PHP dan database MySQL. Pembuatan sistem ini, menggunakan metode Extreme Programming di dalamnya dilakukan dengan langkah penelitian diantaranya mengidentifikasi masalah, mengumpulkan data, menerapkan metode Extreme Programming, dan melakukan implementasi. Sistem absensi sekolah yang telah di bangun dengan fitur-fitur berhasil sempurna di buktikan dengan pengujian fitur sistem menggunakan black box testing dengan tingkat keberhasilan 100%. Dari hasil pengujian tersebut pemanfaatan QR-Code Vaksin Covid-19 dapat digunakan untuk absensi kehadiran dan kepulangan

A Distributed Newton Method for Network Utility Maximization

Most existing work uses dual decomposition and subgradient methods to solve Network Utility Maximization (NUM) problems in a distributed manner, which suffer from slow rate of convergence properties. This work develops an alternative distributed Newton-type fast converging algorithm for solving network utility maximization problems with self-concordant utility functions. By using novel matrix splitting techniques, both primal and dual updates for the Newton step can be computed using iterative schemes in a decentralized manner with limited information exchange. Similarly, the stepsize can be obtained via an iterative consensus-based averaging scheme. We show that even when the Newton direction and the stepsize in our method are computed within some error (due to finite truncation of the iterative schemes), the resulting objective function value still converges superlinearly to an explicitly characterized error neighborhood. Simulation results demonstrate significant convergence rate improvement of our algorithm relative to the existing subgradient methods based on dual decomposition.Comment: 27 pages, 4 figures, LIDS report, submitted to CDC 201