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All Journal BULETIN FISIKA
I Gde Antha Kasmawan
Program Studi Fisika, Fakultas Matematika dan Ilmu Pengetahuan Alam, Universitas Udayana

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Penyesuaian Nilai Percepatan Tanah Maksimum Berdasarkan Modifikasi Konstanta Atenuasi dengan Data Accelerograph Tahun 2020-2023 Wilayah Bali Mayumi Cahyandari; Winardi Tjahyo Baskoro; I Putu Dedy Pratama; I Made Yuliara; Hery Suyanto; I Gde Antha Kasmawan
BULETIN FISIKA Vol 25 No 2 (2024): BULETIN FISIKA
Publisher : Departement of Physics Faculty of Mathematics and Natural Sciences, and Institute of Research and Community Services Udayana University, Kampus Bukit Jimbaran Badung Bali

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24843/BF.2024.v25.i02.p12

Abstract

This study aims to determine the empirical formula model of maximum ground acceleration (PGA) in the Bali region by modifying the attenuation constant based on accelerograph data from 2020-2023 obtained from the BMKG Class II Sanglah Geophysical Station. The data used consists of 443 accelerograph recordings from 146 earthquake events, with a coverage area of ??113.51 ° - 115.83 ° E and 12.56 ° - 7.71 ° S. Through linear regression analysis, the empirical PGA model for the Bali region is obtained: log10 PGA = (-1.817) log10 (R) + (0.809) M - 0.089. This model is also compared with the attenuation model from Donovan, Setiawan, and Lin and Wu, with the results showing that the developed model has a very strong correlation of 0.782 between the PGA from observations and the PGA from the model which is included in the very strong category. In addition, the MSE value of 0.209 and RMSE of 0.457 from this model indicate that the model has a good level of accuracy in predicting PGA values. These findings provide a significant contribution in improving seismic risk prediction in the Bali region, which can be used as a basis for more effective disaster mitigation planning.
Solution of Time-Independent Schrodinger Equation (TISE) by Using Finite Difference Approach IGA Widagda; Nengah Artawan; I Gde Antha Kasmawan; I Wayan Gede Suharta; Ni Putu Yuni Nurmalasari
BULETIN FISIKA Vol 26 No 1 (2025): BULETIN FISIKA
Publisher : Departement of Physics Faculty of Mathematics and Natural Sciences, and Institute of Research and Community Services Udayana University, Kampus Bukit Jimbaran Badung Bali

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

This research investigates the numeric solution of the time-independent Schrödinger equation for the quantum harmonic oscillator by finite difference approach. The harmonic oscillator, described by a quadratic function potential, is a fundamental model in quantum mechanics due to its broad applications, ranging from molecular vibrations to quantum field theory. The time-independent Schrödinger equation is a second-order differential equation that typically poses challenges when solved analytically for complex potentials. The finite difference method become an attractive choice as it transforms the continuous differential equation into a system of linear equations that can be computationally solved through computer programming code. In this study, the spatial domain is discretized, and the second derivative is calculated by using central differences, transforming the TISE into a tridiagonal matrix representing Hamiltonian of system. By finding solutions to this matrix eigenvalue problem, wavefunctions and eigenvalues are obtained. The study results demonstrate that the finite difference approach effectively solves the TISE for the harmonic oscillator. The results obtained by using the finite difference method closely approximate the analytical results. The linear regression results show respectively that the gradient (?1), regression coefficient (?0) and coefficient of determination (R²) approach ideal values of 1, 0, and 1. The z-test results also show that the value of calculated z < critical z, indicating that the wavefunction and probability density, whether estimated by using finite difference approach or analytical methods, are equivalent with confidence level of 95 percent. Abstrak Penelitian ini menyelidiki penyelesaian numerik dari persamaan Schrodinger takgayut waktu untuk osilator harmonik kuantum dengan metode beda hingga. Osilator harmonik dinyatakan dengan potensial berbentuk fungsi kuadrat, adalah model dasar dalam mekanika kuantum karena aplikasinya yang luas mulai dari vibrasi molekul sampai teori medan kuantum. Persamaan Schrodinger bergantung waktu, adalah persamaan diferensial orde dua, yang biasanya menghadapi masalah jika diselesaikan secara analitik untuk potensial yang bentuknya komplek. Metode beda hingga menjadi pilihan yang menarik, mengubah persamaan differensial kontinyu menjadi sebuah sistem persamaan linear yang dapat diselesaikan secara komputasi dengan kode program komputer. Dalam penelitian ini domain spasial dideskritkan dan turunan kedua dihitung dengan beda sentral, mentransformasi TISE ke dalam matrik tridiagonal yang merepresentasikan Hamiltonian dari sistem. Dengan mencari penyelesaian dari masalah matrik eigenvalue ini, diperoleh fungsi gelombang dan energi. Hasil penyelidikan menunjukkan metode beda hingga mampu menyelesaikan TISE untuk osilator harmonik dengan efektif. Hasil yang diperoleh metode beda hingga sangat mendekati hasil analitik. Dari hasil regresi linear memperlihatkan secara berurutan nilai gradien (m), koefisien regresi (c) dan koefisien determinasi (R2) mendekati nilai ideal yaitu: 1, 0 dan 1. Hasil uji z juga memperlihatkan nilai z hitung < z kritis, mengindikasikan hasil perhitungan fungsi gelombang dan rapat kebolehjadian baik dengan metode beda hingga maupun analitik adalah sama dengan tingkat kepercayaan 95 persen.