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Ditemukan 212734 dokumen yang sesuai dengan query
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Ahmad S. Aziz A.
"Sebuah model efektif telah didapatkan untuk ion magnetik terisolasi, yang dapat menunjukkan konfigurasi high-spin pada keadaan dasarnya, yakni terbentuknya kopling Hund. Dengan menggunakan model tersebut, kami menguji kestabilan kopling Hund saat sistem diberikan pemanasan. Nilai termodinamika rerata dari kuadrat total spin elektron valensi pada sistem (hS2iave) ternyata konstan sampai nilai suhu tertentu (suhu breakdown), lalu turun secara monotonik, kemudian mencapai harga asimtotik pada suhu sangat tinggi. Selain itu, kami mengamati efek irradiasi foton dengan cara mengkopel Hamiltonian model dengan medan elektromagnetik pada berbagai harga frekuensi. Kami dekomposisi elemen matriks transisi atas tiga kontribusi: kontribusi dipol listrik, Zeeman, dan ”crossing”. Kami belum berhasil menyelesaikan perhitungan kontribusi dipol listrik, alih-alih kami mengusulkan asumsi sementara bahwa kontribusi ini hilang karena perturbasinya tak tergantung spin. Dengan asumsi ini maka kontribusi ”crossing” menjadi hilang pula. Mengejutkan bahwa setelah dilakukan perhitungan, kami temukan bahwa kontribusi Zeeman juga hilang untuk setiap transisi dari suatu keadaan dasar ke sembarang keadaan terkesitasi. Secara keseluruhan, hasil yang kami dapatkan menunjukkan bahwa kopling Hund kokoh terhadap gangguan irradiasi foton berapapun frekuensinya.

An effective model is obtained for an isolated magnetic ion that leads to the high-spin configuration ground states, i.e. the Hund’s coupling. Using this model, we test the stability of the Hund’s coupling by putting the system in the heating environment. The thermodynamic average of the square values of total spin of the valence electrons in the system (hS2iave) stays constant upto a certain value of temperature, which is referred to as the breakdown temperature, then decreases monotonically, and reaches an asymptotic value at very high temperature. In addition, we investigate the effects of electromagnetic (EM) or photon irradiation. To do this, we couple the model Hamiltonian with an electromagnetic field of various frequency values. We decompose the transition matrix element into three contributions: the electric dipole, Zeeman, and ”crossing” contributions. We have not completed the calculations for the dipole contributions, rather we propose a temporary assumption that this contribution vanishes due to the spin-independent nature of the perturbation. With this assumption the ”crossing” contribution also vanishes accordingly. Surprisingly, by actual calculations, we also find that the Zeeman contribution also vanishes for any transtition from a groundstate to an excited state. Overall, our results suggest that the Hund’s coupling is robust against a disturbance by photon irradiation at any frequency.
"
Depok: Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Indonesia, 2013
T35804
UI - Tesis Membership  Universitas Indonesia Library
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"Paper ini menyampaikan hasil studi eksperimen pada sambungan komposit yang terdiri dari pelat beton komposit, balok baja tipe I yang dilas terhadap kolom komposit concrete-filled-tube (CFT).
Parameter yang diteliti adalah rasio tulangan pelat, tebal kolom, persentase dari shear connectors dan pengaruh dari beton di dalam kolom. Hasil studi eksperimen menunjukkan bahwa tulangan pada pelat
memberikan efek kontinuitas yang parsial pada sambungan sehingga sambungan komposit yang diteliti pada studi ini bisa
dikategorikan sebagai sambungan semi - rigid. Paper ini juga menyajikan metode untuk memodelkan diagram momen-rotasi dari sambungan jenis ini dengan menggunakan model kurva tri-linear dan persamaan untuk mendefinisikan kekakuan rotasi awal (initial rotational stiffness) dan momen ultimate. Jika dibandingkan dengan hasil eksperimen, hasil yang didapat dengan menggunakan
model dan persamaan yang diajukan memberikan hasil yang cukup dekat.

Abstract
This paper presents the main results of an experimental study on composite connections comprising steel I -beam welded to concrete -
filled-tube (CFT) column. The influences of reinforcement ratio, column thickness, percent age of shear connectors and the presence of concrete filled column are investigated. The experimental results indicate that reinforcements in the slab can provide the connection
with partial continuity, such that composite connections with CFT column could be categorised as semi -rigid. A method to predict the moment rotation relationship of such composite connections is
then presented where a tri-linear moment-rotation model was chosen to represent its behaviour. The equations to define its initial rotational stiffness and ultimate moment resistance are derived. All the
proposed equations are compared with the experimental observations and a reasonable good agreement is obtained."
[Fakultas Teknik UI, Fakultas Teknik Universitas Indonesia], 2009
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Artikel Jurnal  Universitas Indonesia Library
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Andy Sumarta
"Telah dilakukan pengamatan mengenai dinamika domain wall pada bahan Permalloy berbentuk nanowire dengan menggunakan software simulasi mikromagnetik OOMMF berdasarkan persamaan Landau-Lifshitz-Gilbert (LLG). Pengamatan dinamika domain wall dilakukan pada nanowire dengan panjang 2000 nm, variasi lebar dari 100 sampai 200, dan variasi ketebalan 2,5 nm dan 5,0 nm dibawah pengaruh medan magnet luar dalam bentuk pulsa. Kecepatan domain wall bertambah ketika medan magnet luar yang diberikan di perbesar dan kemudian mengalami penurunan scara drastis setelah medan magnet luar yang diberikan melampaui medan magnet kritis yang di sebut medan Walker breakdown. Sebelum medan magnet luar yang diberikan melebihi nilai medan Walker breakdown, domain wall bergerak dengan mempertahankan struktur transverse. Setelah melampaui nilai medan Walker breakdown, struktur transverse pada domain wall mengalami perubahan menjadi struktur vortex/anti-vortex.

We have investigated the domain wall dynamics in Permalloy material with nanowire shape using public micromagnetic simulation software, OOMMF based on the Landau-Lifshitz-Gilbert equation. We have observed domain wall dynamic for different thickness and width respect to external magnetic field. Domain wall velocity increases as the external magnetic field increase and abruptly decreases after critical field which is called Walker breakdown field. Before Walker breakdown, domain wall moving while keeping transverse inner structure, and after Walker breakdown, transverse inner structure transform to vortex/anti-vortex inner structure."
Depok: Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Indonesia, 2011
S1065
UI - Skripsi Open  Universitas Indonesia Library
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Watson, J. K. (James Kenneth), 1929-
New York: John Wiley & Sons, 1980
621.3 WAT a
Buku Teks  Universitas Indonesia Library
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Dhawud Sabilur Razaq
"Sampel polikristalin La0.7Ba0.1Sr0.2Mn1-xCuxO3 x = 0; 0.05; 0.10; 0.15 telah disintesis menggunakan metode sol-gel. Pengaruh substitusi tembaga terhadap sifat kemagnetan dan kelistrikan dari sampel La0.7Ba0.1Sr0.2Mn1-xCuxO3 telah diselidiki menggunakan X-Ray Diffractometer XRD, Scanning Electron Microscope SEM, Energy Dispersive X-Ray EDX Vibrating Sample Magnetometer VSM , dan Cryogenic Magnetometer. Parameter struktural yang telah didapatkan menggunakan analisis struktural rietveld refinement menunjukkan bahwa sampel La0.7Ba0.1Sr0.2Mn1-xCuxO3 memiliki struktur rhombohedral dengan space group R-3c tanpa adanya impuritas yang dapat dideteksi. Tidak adanya impuritas dalam sampel yang telah disintesis juga terlihat pada hasil yang didapat dari EDX. Perubahan ukuran grain terjadi ketika tembaga telah tersubstitusi pada sampel.
Analisis struktural yang telah dilakukan menunjukkan adanya korelasi antara struktur kristal terhadap sifat kemagnetan dari sampel. Transisi fasa feromagnetik metal menjadi paramagnetic insulator terjadi pada semua nilai konsentrasi doping. Hasil penelitian yang telah dilakukan membuktikan bahwa substitusi tembaga akan melemahkan interaksi feromagnetik double exchange sehingga berakibat menurunnya magnetisasi saturasi dan temperatur transisi sampel.

Polycrystalline sample of La0.7Ba0.1Sr0.2Mn1 xCuxO3 X 0 0.05 0.10 0.15 was synthesized using sol gel method. The effect of copper substitution on the magnetic and electrical properties has been investigated by means of X Ray diffraction XRD, Scanning Electron Microscope SEM, Energy Dispersive X Ray EDX, Vibrating Sample Magnetometer VSM, and Cryogenic Magnetometer. The structural parameter obtained using structural analysis by rietveld refinement shows that sample La0.7Ba0.1Sr0.2Mn1 xCuxO3 crystallize in rhombohedral structure with R 3c space group without any detectable impurity. This argument is confirmed from EDX measurement result. Different grain size are noticeable for different copper concentration.
The structural analysis suggested that there are a strong correlation between structure and magnetic property. Ferromagnetic metal to paramagnetic insulator transition occurred at all copper concentration. The experimental results shows that ferromagnetic double exchange interaction will grow weaker upon copper substitution on manganese ion. This will cause a reduction in the magnetization saturation and metal to insulator transition temperature.
"
Depok: Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Indonesia, 2018
S-Pdf
UI - Skripsi Membership  Universitas Indonesia Library
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Stefanita, Carmen-Gabriela
"This book offers broad coverage of magnetism, revealing key concepts on which many practical applications rest. Traditional subjects are discussed in the first half, and the second section includes coverage of today's technological achievements."
Berlin : Springer, 2012
e20425255
eBooks  Universitas Indonesia Library
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Knopp, Tobias
"This volume provides a comprehensive overview of recent developments in magnetic particle imaging (MPI), a novel imaging modality. Using various static and oscillating magnetic fields, and tracer materials made from iron oxide nanoparticles, MPI can perform background-free measurements of the particles’ local concentration. The method exploits the nonlinear remagnetization behavior of the particles and has the potential to surpass current methods for the detection of iron oxide in terms of sensitivity and spatiotemporal resolution. Starting from an introduction to the technology, the topics addressed include setting up an imaging device, assessment of image quality, development of new MPI tracer materials, and the first preclinical results.
"
Berlin : [Springer, ], 2012
e20425221
eBooks  Universitas Indonesia Library
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Hentihu, Fatimah Kunti
"ABSTRAK
Tesis ini membahas mengenai faktor koreksi rekombinasi ion untuk bilik ionisasi pada berkas foton FFF Flattening-Filter-Free kemudian membandingkan hasilnya dengan berkas foton konvensional. Evaluasi faktor koreksi rekombinasi ion dilakukan untuk bilik ionisasi FC65-G, SNC600c dan CC13. Pengukuran menggunakan ketiga bilik ionisasi dilakukan di dalam fantom air dan menggunakan foton FFF dan foton konvensional 6 MV dari pesawat Varian Trilogy. Nilai faktor koreksi rekombinasi ion untuk ketiga bilik ionisasi kemudian diperoleh dari perhitungan dengan menggunakan metode dua tegangan sederhana dan fitting kurva Jaffe plot. Pengukuran juga dilakukan untuk beberapa variasi kedalaman dan variasi ukuran lapangan. Nilai faktor rekombinasi ion yang diperoleh secara keseluruhan dari ketiga bilik ionisasi menunjukkan bahwa nilai koreksi pada berkas foton FFF memilliki nilai yang lebih besar dibandingkan berkas foton konvemsional dengan perbedaan < 0,5 . Sementara dengan menggunakan beberapa variasi kedalaman dan ukuran, diketahui bahwa nilai koreksi rekombinasi ion berkurang dengan bertambahnya kedalaman variasi < 0,3 dan meningkat dengan bertambahnya ukuran lapangan variasi < 0,1 . Nilai koreksi rekombinasi ion yang diperoleh dari fitting kurva Jaffe plot linier memiliki perbedaan sebesar le; 7,649 bila dibandingkan dengan metode dua tegangan. Sementara perbedaan nilai koreksi rekombinasi ion yang diperoleh dari fitting kurva kuadratik dan fitting kurva kuadratik eksponensial terhadap metode dua tegangan adalah sebesar le; 0,5882 dan le; 1,798 . Selain koreksi rekombinasi ion, pada penelitian ini juga dilakukan evaluasi terhadap nilik faktor koreksi polaritas pada berkas foton FFF. Nilai koreksi polaritas berkas foton FFF dengan berkas foton konvensional memiliki perbedaan sebesar < 0,15 .. Nilai koreksi rekombinasi ion maupun koreksi polaritas untuk ketiga bilik ionisasi tidak memiliki perbedaan yang dignifikan bila dibandingan antara berkas foton konvensional dengan foton FFF.

ABSTRACT
This study focused on ion recombination factor for ionization chambers in FFF flattening filter free photon beams and then compared the result against conventional photon beams. The evaluation of ion recombination correction factor was performed using FC65 G, SNC600c, and CC13 ionization chambers. Measurements using the three ionization chambers were performed within the water fantom and using 6 MV FFF and conventional photon beams from the Varian Trilogy linac. The ion recombination correction factor value for the three ionization chambers were obtained from the calculation using the simple two voltage method and Jaffe plot curve fitting. Measurements were also performed for several depth and field size variations. The ion recombination factor value obtained from all three ionization chambers were higher for FFF photon beams than for the conventional photon beams with a difference of 0.5 . While using several variations of depth and size, the results showed that the ion recombination correction value decreased with increasing depth with variation 0.3 and increased with increasing field size with variation 0.1 . The ion recombination correction value obtained from the linear Jaffe plot curve fitting had a difference le 7.649 when compared to the two voltage method. While differences in ion recombination correction values obtained from quadratic curve fitting and exponential quadratic curve fitting to two voltage methods were le 0.5882 and le 1.798 . In addition to ion recombination correction, this study also evaluated the polarity correction factor in the FFF photon beams. The polarity correction value of FFF photon beam with conventional photon beam had a difference 0.15 . The value of ion recombination and polarity correction for the three ionization chambers in FFF photon beams has no significant difference compared to conventional photon beams.
"
2018
T51417
UI - Tesis Membership  Universitas Indonesia Library
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Linda Samuel Tjiputra
"ABSTRAK
Penelitian mi bertujuan untuk mempelajari mekanisme adsorpsi ion Ni(II) amoniakal dan ion sulfat pada permukaan y-Al203 dan menentukan asumsi model adsorpsi yang sesuai. Percobaan adsorpsi dilakukan dengan metode pengguncangan. Metode pengguncangan ini dilakukan untuk mencari kondisi terbaik, isotenn adsorpsi dan pengaruh perubahan kuat ion. Pengaruh perubahan kuat ion pada proses adsorpsi dilakukan dengan penambahan elektrolit pendukung yaitu KNO3 dengan konsentrasi yang bervariasi antara 0,01 - I M.
Pada penelitian mi adsorpsi maksimum ion Ni(II) amoniakal diperoleh pada pH 11 dengan pengguncangan selama 45 menit. Sedangkan adsorpsi maksimum ion SO4 diperoleh pada pH 2 dengan pengguncangan selama I jam.
Mekanisme yang teijadi pada adsorpsi ion Ni(ll) amoniakal tergantung pada spesies yang terbentuk dalam larutannya dan diasumsikan membentuk kompleks
'lengkung Iuar (outer-sphere) karena adsorpsinya relatif dipengaruhi oleh perubahan kuat ion. Sedangkan mekanisme yang terjadi path adsorpsi ion SO4 diperkirakan melalui pertukaran ion dan diasumsikan membentuk kompleks 'Iengkung dalam' (innersphere) karena adsorpsinya relatif tidak dipengaruhi oleh perubahan kuat ion. Isoterm adsorpsi kedua ion mi mengikuti isoterm adsorpsi Langmuir yaitu dengan membentuk lapisan monomolekuler pada pusat-pusat aktif permukaan adsorben."
Depok: Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Indonesia, 1994
S-Pdf
UI - Skripsi Membership  Universitas Indonesia Library
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Syaefudin Jaelani
"[ABSTRAK
Kuantisasi Lagrangian model point-coupling bergantung densitas menghasilkan
Lagrangian Hartree-Fock yang terdiri atas suku direct dan exchange.
Identitas Fierz diaplikasikan pada suku exchange agar bisa disusun bersama
dengan suku direct membentuk Lagrangian efektif. Dengan menggunakan persamaan
Euler-Lagrange akan didapat persamaan gerak dan massa efektif sistem.
Dari Hamiltonian sistem diperoleh energi ikat sistem per nukleon, massa
efektif, tekanan dan kompresibilitas. Dari hasil yang diperoleh, kontribusi
suku exchange kecil pada massa efektif nukleon materi nuklir simetrik. Namun
pada keadaan lain, kontribusi yang signi kan terlihat pada energi ikat
per nukleon di materi nuklir simetrik dan materi netron, massa efektif materi
netron, dan energi ikat per nukleon pada densitas rendah dari materi netron.

ABSTRACT
Point-coupling model Lagrangian is quantized to obtain the Hartree-Fock
Lagrangian which contained direct and exchange terms. Fierz identity applied
to the exchange term to be rearranged together with the direct term to obtain
the e ective Lagrangian. By using the Euler-Lagrange equation, we will obtain
the equation of motion and the e ective mass of the system. From the Hamiltonian
will obtain the binding energy per nucleon, e ective mass, pressure
and compressibility. The results show that the exchange term contribution
is small on nucleon e ective mass of symmetric nuclear matter. But in the
other conditions, the signi cant contribution are observed on binding energy
per nucleon of asymmetric nuclear matter, neutron e ective mass, and binding
energy per nucleon in asymmetric nuclear matter in low density;Point-coupling model Lagrangian is quantized to obtain the Hartree-Fock
Lagrangian which contained direct and exchange terms. Fierz identity applied
to the exchange term to be rearranged together with the direct term to obtain
the e ective Lagrangian. By using the Euler-Lagrange equation, we will obtain
the equation of motion and the e ective mass of the system. From the Hamiltonian
will obtain the binding energy per nucleon, e ective mass, pressure
and compressibility. The results show that the exchange term contribution
is small on nucleon e ective mass of symmetric nuclear matter. But in the
other conditions, the signi cant contribution are observed on binding energy
per nucleon of asymmetric nuclear matter, neutron e ective mass, and binding
energy per nucleon in asymmetric nuclear matter in low density;Point-coupling model Lagrangian is quantized to obtain the Hartree-Fock
Lagrangian which contained direct and exchange terms. Fierz identity applied
to the exchange term to be rearranged together with the direct term to obtain
the e ective Lagrangian. By using the Euler-Lagrange equation, we will obtain
the equation of motion and the e ective mass of the system. From the Hamiltonian
will obtain the binding energy per nucleon, e ective mass, pressure
and compressibility. The results show that the exchange term contribution
is small on nucleon e ective mass of symmetric nuclear matter. But in the
other conditions, the signi cant contribution are observed on binding energy
per nucleon of asymmetric nuclear matter, neutron e ective mass, and binding
energy per nucleon in asymmetric nuclear matter in low density;Point-coupling model Lagrangian is quantized to obtain the Hartree-Fock
Lagrangian which contained direct and exchange terms. Fierz identity applied
to the exchange term to be rearranged together with the direct term to obtain
the e ective Lagrangian. By using the Euler-Lagrange equation, we will obtain
the equation of motion and the e ective mass of the system. From the Hamiltonian
will obtain the binding energy per nucleon, e ective mass, pressure
and compressibility. The results show that the exchange term contribution
is small on nucleon e ective mass of symmetric nuclear matter. But in the
other conditions, the signi cant contribution are observed on binding energy
per nucleon of asymmetric nuclear matter, neutron e ective mass, and binding
energy per nucleon in asymmetric nuclear matter in low density, Point-coupling model Lagrangian is quantized to obtain the Hartree-Fock
Lagrangian which contained direct and exchange terms. Fierz identity applied
to the exchange term to be rearranged together with the direct term to obtain
the e ective Lagrangian. By using the Euler-Lagrange equation, we will obtain
the equation of motion and the e ective mass of the system. From the Hamiltonian
will obtain the binding energy per nucleon, e ective mass, pressure
and compressibility. The results show that the exchange term contribution
is small on nucleon e ective mass of symmetric nuclear matter. But in the
other conditions, the signi cant contribution are observed on binding energy
per nucleon of asymmetric nuclear matter, neutron e ective mass, and binding
energy per nucleon in asymmetric nuclear matter in low density]"
2015
T43226
UI - Tesis Membership  Universitas Indonesia Library
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