Hasil Pencarian  ::  Simpan CSV :: Kembali

"Magnetohydrodynamics (MHD) adalah suatu model yang baik untuk memodelkan proses dinamo pada bumi, hal ini dikarenakan inti luar bumi adalah suatu fluida yang bergerak. Pada MHD ini perlu dipecahkan secara simultan beberapa persamaan yaitu persamaan induksi, persamaan Navier-Stokes, persamaan kekekalan massa, persamaan Poisson untuk gravitasi, persamaan panas dan persamaan state. Pada skripsi ini hanya akan diperhatikan permasalahan dinamo kinematika, yaitu bagaimana aliran ( ) yang telah diberikan dapat menjaga medan magnet ( ) agar tidak meluruh menuju nol ketika waktu menuju tak hingga. Aliran Pekeris, Accad and Skholler (PAS) (1973) adalah salah satu contoh aliran yang berhasil menghasilkan proses dinamo. Bachtiar, Ivers dan James (BIJ, 2006) mencoba melakukan planarisasi pada aliran PAS, dimana planarisasi adalah metode yang digunakan untuk mengkonstruksi aliran yang sejajar dengan suatu bidang (aliran planar) terhadap aliran yang diberikan. Dalam proses planarisasi yang dilakukan, ditemui suatu kendala yaitu fungsi stream yang tidak memenuhi kondisi rigid boundary. Dalam skripsi ini akan dilakukan modifikasi terhadap fungsi stream tersebut sehingga hasil modifikasinya memenuhi kondisi rigid boundary. Serta akan diberikan implementasi dan simulasi hasil modifikasi fungsi stream dengan menggunakan program pada MATLAB.

---

AbstractMagnetohydrodynamics (MHD) is a model which is used to explain the dynamo process on the earth. It happened because the earth's outer core is a moving fluids. The induction equation, the Navier-Stokes equation, the mass conservation equation, Poisson's equation for gravity, the heat equation and an equation of state are needed to be solved simultaneously in MHD. This final report will only focus on kinematic dynamo problem, the problem is to determine whether the flow ( ) can maintain the magnetic field ( ). The Pekeris, Accad and Skholler (PAS, 1973) flow is an example of a flow that can produce the dynamo process. Bachtiar, Ivers and James (BIJ, 2006) try to do planarizing process on the PAS flow, where the planarizing process is a method to construct the flow parallel to a plane (planar flow) of a given flow. In the planarizing process, BIJ find an obstacle that is the stream function cannot satisfy the rigid boundary condition. In this final report the modified stream function is given, so that result of the modified can satisfy the rigid boundary condition. We used MATLAB in our simulation. "

"ABSTRAKSistem terkorelasi kuat adalah sistem dimana skala energi untuk interaksi antar partikel tidak lagi dapat diabaikan. Dynamical Mean Field Theory(DMFT) menjadi salah satu metode yang banyak dikenal sebagaimetode ampuh untuk menjelaskan fisika dari sistem terkorelasi kuat. Disini kami mempelajari metodepenyelesaian impuritas yang tersedia di DMFT untuk model Hubbard, model paling sederhana dalam sistemterkorelasi kuat. Dengan melihat berbagai keterbatasan metode penyelesaian impuritas dengan sumberdayanumerik yang murah, kami mengembangkan metode penyelesaian impuritas dengan numerik yang murahlainnya yang dikembangkan dari metode medan rata-rata dengan melibatkan fluktuasi okupasi sebagai kuantitasnumerik. Dengan melihat efek fluktuasi, kami membandingkan hasil tersebut dengan metode penyelesaianimpuritas lainnya, yakni medan rata-rata dan iterasi perturbasi teori yang dipelajari pada keadaan paramagnetikdan antiferomagnetik. Kami simpulkan bahwa fluktuasi okupasi belum sepenuhnya mampu menjadi metodepenyelesaian impuritas yang baik, namun memberikan hasil yang menarik untuk digunakan sebagai koreksi dariiterasi perturbasi teori.

---

ABSTRACT

Strongly correlated system is physical system where the interaction among particle cannot be neglected.

Dynamical Mean Field Theory(DMFT) becomes one of the established method to explain and calculate physical

observable of strongly correlated system. Here we study the impurity solver in DMFT for Hubbard model, the

simplest model for strongly correlated system. We realizing that exact impurity solver gives high numerical cost,

where approximate impurity solver gives relative low numerical cost. Here we develop another low numerical

cost to aim more exact result than approximate method, where we developed it from mean-field method where is the occupation fluctuation is taking into account in the semi-classical sense. We compare this method by another lower numerical impurity solver, i.e mean-field and iterated perturbation theory, where they are studied in restricted case of paramagnetic and unrestricted case of magnetic ordering. We concluded that occupation fluctuation not really giving exact result if we compared to mean-field and iterated perturbation theory, but becomes interesting if we implement occupation fluctuation as iterated perturbation theory correction.

"

"[ABSTRAK

Fenomena halo neutron dalam nuklir digambarkan adanya kemunculan 'ekor' dan

adanya 'ruang kosong' antara core dan ekor pada distribusi neutron akibat energi

ikat yang lemah. Metode analisa halo yang dikembangkan oleh V. Rotival dkk [Phys.

Rev. C79, 054308 (2009)] untuk menghitung besaran-besaran halo berdasarkan mo-

del Hartree-Fock-Bogoulibov (HFB) pada isotop Cr dan isotop Sn menjadi salah sa-

tu alternatif untuk mempelajari fenomena halo. Berbeda dengan Rotival dkk, kami

menggunakan model Relativistic Mean Field (RMF) pada penelitian ini. Berbeda

dengan hasil perhitungan berdasarkan model HFB, kami fokus mengamati perilaku

spektrum single particle energy level 1g9~2 terhadap kemunculan halo pada isotop

Cr. Selain itu, pada penelitian ini kami juga memperlajari dampak dari suku cross

coupling meson ! − , suku-suku tensor dan suku pertukaran elektromagnetik pada

model RMF terhadap kemunculan halo pada isotop Cr dan isotop Sn. Hasil perhi-

tungan prediksi kemunculan halo berdasarkan model RMF lebih besar dibandingkan

dengan hasil perhitungan berdasarkan model HFB (`NhaloeRMF > `NhaloeHFB):

---

ABSTRACT

In neutron halo phenomenon, the neutron density displays an unusually extended

'tail' and 'empty space' between the core and the tail due to weak binding energy.

New analysis method of the halo was developed by V. Rotival, et al.[Phys. Rev. C79,

054308 (2009)] in Cr-isotopes and Sn-isotopes, its usually applied with Hartree-Fock-

Bogoliubov (HFB) model. Unlike them, we use the model of the Relativistic Mean

Field (RMF) in this research. We observed dierent behavior at the level 1g9~2 in line

with appearance of halo in Cr-isotopes. Moreover, in this research we also studied

the eects of cross coupling meson ! − , tensor, and electromagnetic exchange in

RMF model appearance of halo in Cr-isotopes and Sn-isotopes. The prediction of

the existence of halo based on RMF model is greater than the prediction based on

HFB model (`NhaloeRMF > `NhaloeHFB):, In neutron halo phenomenon, the neutron density displays an unusually extended

'tail' and 'empty space' between the core and the tail due to weak binding energy.

New analysis method of the halo was developed by V. Rotival, et al.[Phys. Rev. C79,

054308 (2009)] in Cr-isotopes and Sn-isotopes, its usually applied with Hartree-Fock-

Bogoliubov (HFB) model. Unlike them, we use the model of the Relativistic Mean

Field (RMF) in this research. We observed dierent behavior at the level 1g9~2 in line

with appearance of halo in Cr-isotopes. Moreover, in this research we also studied

the eects of cross coupling meson ! − , tensor, and electromagnetic exchange in

RMF model appearance of halo in Cr-isotopes and Sn-isotopes. The prediction of

the existence of halo based on RMF model is greater than the prediction based on

HFB model (`NhaloeRMF > `NhaloeHFB):]"

"This thesis presents an accurate and advanced numerical methodology to remedy difficulties such as direct numerical simulation of magnetohydrodynamic (MHD) flow in computational fluid dynamics (CFD), grid generation processes in tokamak fusion facilities, and the coupling between the surface tension force and Lorentz force in the metallurgical industry. In addition, on the basis of the numerical platform it establishes, it also investigates selected interesting topics, e.g. single bubble motion under the influence of either vertical or horizontal magnetic fields. Furthermore, it confirms the relation between the bubble’s path instability and wake instability, and observes the anisotropic (isotropic) effect of the vertical (horizontal) magnetic field on the vortex structures, which determines the dynamic behavior of the rising bubble.The direct numerical simulation of magnetohydrodynamic (MHD) flows has proven difficult in the field of computational fluid dynamic (CFD) research, because it not only concerns the coupling of the equations governing the electromagnetic field and the fluid motion, but also calls for suitable numerical methods for computing the electromagnetic field. In tokamak fusion facilities, where the MHD effect is significant and the flow domain is complex, the process of grid generation requires considerable time and effort. Moreover, in the metallurgical industry, where multiphase MHD flows are usually encountered, the coupling between the surface tension force and Lorentz force adds to the difficulty of deriving direct numerical simulations."

"This book was inspired by the general observation that the great theories of modern physics are based on simple and transparent underlying mathematical structures – a fact not usually emphasized in standard physics textbooks – which makes it easy for mathematicians to understand their basic features. It is a textbook on quantum theory intended for advanced undergraduate or graduate students: mathematics students interested in modern physics, and physics students who are interested in the mathematical background of physics and are dissatisfied with the level of rigor in standard physics courses. More generally, it offers a valuable resource for all mathematicians interested in modern physics, and all physicists looking for a higher degree of mathematical precision with regard to the basic concepts in their field."