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All Journal Jurnal Fisika Unand Journal of Physics: Theories and Applications Jurnal Penelitian Pendidikan IPA (JPPIPA) Communications in Science and Technology Jurnal Ilmu Fisika
Zulfi Abdullah
Theoretical Physics Laboratory, Department Of Physics, Faculty Of Mathematics And Natural Sciences, Universitas Andalas, Kampus Unand Limau Manis, Padang 25163
Agriculture, Biological Sciences & Forestry Astronomy Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Earth & Planetary Sciences Education Electrical & Electronics Engineering Energy Engineering Materials Science & Nanotechnology Physics

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Analisis Solusi Persamaan Burger Sebagai Solusi Soliton Menggunakan Transformasi Hopf-Cole Ripai, Ahmad; Abdullah, Zulfi; Syafwan, Mahdhivan
Jurnal Fisika Unand Vol 8 No 2 (2019)
Publisher : Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jfu.8.2.171-177.2019

Abstract

Telah dilakukan penelitian untuk menganalisis solusi persamaan Burger dengan menggunakan transformasi Hopf-Cole. Penelitian ini dilatarbelakangi oleh perbedaan solusi yang diperoleh pada persamaan Burger saat mekanisme penyelesaian persamaan ini menggunakan transformasi Hopf-Cole dilandaskan pada transformasi Fourier dan separasi variabel (deret Fourier). Penelitian ini dilakukan dengan mencari solusi persamaan Burger menggunakan transformasi Hopf-Cole melalui mekanisme penyelesaian yang berlandaskan pada transformasi Fourier dan separasi variabel (deret Fourier). Berdasarkan analisis solusi soliton pada persamaan Burger, hanya mekanisme penyelesaian yang berlandaskan transformasi Fourier yang berhasil menemukan solusi soliton walaupun hanya stabil dalam selang waktu 0.1 s. Mekanisme penyelesaian yang berlandaskan separasi variabel (deret Fourier) menghasilkan solusi periodik berupa gelombang meluruh terhadap waktu.Kata kunci: deret Fourier, persamaan Burger, soliton, transformasi Hopf-Cole, transformasi Fourier
Model Kuantisasi Kedua Hamiltonian Resonansi Plasmon Permukaan Terlokalisasi pada Nanologam Bola Lubis, Muhammad Siddiq Ilyas; Abdullah, Zulfi; Muldarisnur, Mulda
Jurnal Fisika Unand Vol 8 No 3 (2019)
Publisher : Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jfu.8.3.212-218.2019

Abstract

Telah diteliti hubungan dispersi pada nanologam bola menggunakan model kuantisasi kedua Hamiltonian (KKH). Hubungan dispersi (HD) diperoleh untuk mengetahui frekuensi resonansi (FR) plasmon pada permukaan bidang batas dielektrik-logam. Sebelumnya, telah diteliti HD pada nanologam planar dan nanowires menggunakan KKH. Pada penelitian lain, juga telah diteliti HD pada nanologam bola (NB) menggunakan persamaan elektrodinamika klasik Maxwell, hasil yang diperoleh adalah FR meningkat pada nilai frekuensi cahaya tinggi saat berinteraksi dengan bidang batas dielektrik-logam. HD juga dapat ditentukan pada geometri NB. Dan pada penelitian ini HD pada NB ditentukan dengan model KKH, kemudian ditransformasi menggunakan transformasi Bogoliubov (TB). FR pada NB meningkat pada rentang energi cahaya tampak yang tinggi, ukuran NB yang lebih kecil, dan pada bilangan kuantum l lebih besar. Hasil tersebut sesuai dengan HD yang diperoleh dari persamaan elektrodinamika klasik Maxwell. Dan HD pada planar dan nanowires lebih kecil dibandingkan HD pada NB. Kata kunci: kuantisasi kedua Hamiltonian, transformasi Bogoliubov, nanologam bola, hubungan dispersi.
Analisis Solusi Spatial dan Temporal Persamaan NLS (Nonlinear Schrödinger) Sebagai Solusi Soliton Menggunakan Metode DVR (Discrete Variable Representation Maulana, Irvan; Abdullah, Zulfi
Jurnal Fisika Unand Vol 9 No 1 (2020)
Publisher : Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jfu.9.1.85-92.2020

Abstract

Analisis solusi persamaan Schrödinger Nonlinear (NLS) dengan menggunakan metode Representasi Variabel Diskrit (DVR) telah dilakukan. Penggunaan metode DVR ini dilakukan dengan mengkontruksikan fungsi basis melalui interpolasi Lagrange dan koefisien spektral yang berdasarkan polinomial Chebyshey pada titik Chebyshev-Gauss-Lobatto (CGL). Hasil simulasi dari metode DVR ini memiliki bentuk yang sama dengan 2 jenis solusi eksak persamaan NLS yaitu Cubic Nonlinear Schrödinger (CNLS) dan Generalized Nonlinear Schrödinger (GNLS), namun memiliki rentang penjalaran yang berbeda. Perbedaan rentang tersebut dikarenakan adanya kondisi awal yang ditetapkan pada metode DVR ini. Penggunaan metode DVR pada pengkondisian CNLS menghasilkan bentuk soliton onsite, sedangkan pada pengkondisian GNLS dihasilkan bentuk soliton onsite namun memiliki amplitudo yang berbeda pada setiap perubahan posisi dan waktu. Analysis of Nonlinear Schrödinger (NLS) equation by using Discrete Variable Representation (DVR) method has been carried out. The DVR method done with built basic function from Lagrange interpolation and spectral coefficient from Chebyshev polynomial in Chebyshev-Gauss-Lobatto (CGL) point. The result of DVR method simulation has same form with 2 type of exact solution of NLS equation are Cubic Nonlinear Schrödinger (CNLS) and Generalized Nonlinear Schrödinger (GNLS), however the result has different distance of propagation. That difference distance caused by initial condition which set on this method. The using of DVR method in CLNS condition produce soliton onsite form, but for GNLS condition produce soliton onsite form too but it has different amplitude for every change of position and time.
The Bilinear Formula in Soliton Theory of Optical Fibers Saputra, Nando; Ripai, Ahmad; Abdullah, Zulfi
Jurnal Fisika Unand Vol 11 No 3 (2022)
Publisher : Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jfu.11.3.387-392.2022

Abstract

Solitons are wave phenomena or pulses that can maintain their shape stability when propagating in a medium. In optical fibers, they become general solutions of the Non-Linear Schrödinger Equation (NLSE). Despite its mathematical complexity, NLSE has been an interesting issue. Soliton analysis and mathematical techniques to solve problems of the equation keep doing. Yan & Chen (2022) introduced them based on bilinear formula for the case of the generalized NLSE extended models into third and fourth-order dispersions and cubic-quintic nonlinearity. In this paper, we review the form of the bilinear formula for the case. We re-observed a one-soliton solution based on the formula and verified the work of the last researcher. Here, the mathematical parameters of position α(0) and phase η are verified to become features of change in horizontal position and phase of one soliton in the (z, t) plane during propagation. In addition, we notice the soliton has established stability. Finally, for the condition Kerr effect focusing or the group velocity dispersion β2 more dominates, we present like the soliton trains in optical fibers under modulation instability of plane wave.
Thermodynamic Analysis of an Endoreversible Bosonic Quantum Otto Refrigerator under Partial Thermalization Shofiyah, Shofiyah; Sutantyo, Trengginas Eka Putra; Abdullah, Zulfi
Jurnal Ilmu Fisika Vol 18 No 2 (2026): September 2026 (Forthcoming Issue)
Publisher : Jurusan Fisika FMIPA Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jif.18.2.117-128.2026

Abstract

Quantum refrigerators (QRs) are pivotal in exploring thermodynamic behavior at microscopic scales. This study investigates a quantum Otto refrigerator using a bosonic gas confined in a cubic potential, operating under finite-time thermalization. We derive key thermodynamic quantities analytically, including the coefficient of performance (COP), cooling power, entropy, and cooling rate. Additionally, we investigate how partial thermalization during the isochoric heating and cooling stages influences overall system performance. The findings reveal a trade-off between COP and cooling power, emphasizing the importance of thermalization duration. Notably, by extending the cooling time relative to heating, the COP can be significantly improved, offering a practical approach to optimizing QR performance under realistic conditions.
Universal I-Love-Q Relation in Anisotropic Quark Stars within Rastall Gravity Yunefi, Haris Maulana; Abdullah, Zulfi
Journal of Physics: Theories and Applications Vol 9, No 2 (2025): Journal of Physics: Theories and Applications
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/jphystheor-appl.v9i2.107796

Abstract

This study investigates the universal I-Love-Q relation in anisotropic quark stars within the Rastall gravity framework. We employ the 4th-order Runge-Kutta numerical method to solve the slow rotation and tidal deformation equations. The analysis utilizes the MIT Bag equation of state with the Bag parameter () and the Color Flavor Locked (CFL) equation of state with the CFL parameter parameter () to model the material properties of anisotropic quark stars. The universal I-Love-Q relation are explored by varying the Rastall parameter () and the anisotropic parameter (). The universal I-Love-Q relation is satisfied when variations in  , , , and do not affect the linear relationship between the moment of inertia (), Love number (), and quadrupole moment (). The universal I-Love-Q relation holds when  and  are varied , but breaks down when ζ and  are altered.
Co-Authors Ahmad Ripai Ahmad Ripai Ahmad Ripai Anak Agung Istri Sri Wiadnyani Boy Angga Boy Angga, Boy Depinta, Ledyva Dwi Pujiastuti Fahendri Fahendri Fahendri, F. Hanifah Azzaura Musyayyadah Ilham Perdana Irvan Maulana Ledyva Depinta Lubis, Muhammad Siddiq Ilyas Mahdhivan Shafwan, Mahdhivan Maulana, Irvan Meqorry Yusfi Mohamad Nazri Abdul Halif Muhammad Siddiq Ilyas Lubis Muldarisnur, Mulda Nando Saputra Oqely Wahyudi Salman Abdul Azis Salman Abdul Azis, Salman Abdul Saputra, Nando Shofiyah Shofiyah Syafwan, Mahdhivan Toni Widianto Trengginas Eka Putra Sutantyo Wahyu Hidayat Wahyu Hidayat Widianto, Toni Wildian Wildian Yunefi, Haris Maulana Zettira, Zahara