Hasil Pencarian  ::  Simpan CSV :: Kembali

Abstrak :
Distorsi dari penjalaran gelombang seismik menghasilkan penampang seismik yang kurang mewakili struktur geologi bawah permukaan. Migrasi, salah satu langkah dalam pengolahan data seismik, dapat memperbaiki masalah tersebut dengan mengurangi efek penjalaran gelombang (depropagasi). Pergeseran Fase, Kirchhoff, dan Finite Difference merupakan metode-metode migrasi yang dibahas pada penilitian ini. Masing-masing dari tiga metode tersebut diaplikasikan kepada dua tipe model struktur geologi yang berbeda, Marmausi dan Salt Dome. Model Marmausi memiliki struktur geologi yang kompleks dan perubahan kecepatan lateral dan vertikal yang signifikan. Sementara Model Salt Dome memiliki variasi kecepatan yang rumit dan dapat menyebabkan banyak difraksi gelombang seismik. Hasil-hasil migrasi dari dua model tersebut menunjukkan bahwa setiap metode migrasi memiliki keunggulan-keunggulan dan kelemahan-kelemahan masing-masing. Metode Kirchhoff memunculkan hasil yang relatif bagus pada area berkemiringan curam dibandingkan dengan metode lainnya. Sementara Metode Finite Difference dapat mengatasi perubahan velocity yang relatif rumit baik secara lateral ataupun vertikal. The Distortion Of seismic wave propagation create a less representative seismic section to the subsurface geological structure. Migration, one step in seismic data basic processing, can fix that problem by diminishing the effect of seimic wave propagation (depropagation). Phase Shift, Kirchhoff, and Finite Difference are migration methods studied in this research. Each of those three methods are applied to two different types of geological structure model, Marmausi and Salt Dome. Marmausi Model has complex geological structure and significant change on both lateral and vertical velocity. While Salt Dome Model has complex velocity variation and can cause a lot of seismic wave diffractions. The migration results produced from those two models show that each migration method has superiorities and also weaknesses. Kirchhoff Method produces relatively good result on steep slope area compare to others. While Finite Difference Method can handle the relatively complex change of velocity both on lateral or vertical.

Abstrak :
ABSTRAK
Intrusi air laut merupakan salah satu masalah kualitas air tanah yang dapat dimodelkan secara matematika. Model matematika diformulasikan dalam bentuk persamaan diferensial parsial yang kemudian solusi persamaan dapat dilakukan secara numerik. Tujuan utama dari penelitian ini adalah menyimulasikan secara numerik intrusi air laut pada suatu akuifer terkekang. Untuk menyimulasikan intrusi air laut, diperlukan persamaan aliran air tanah dependent-density atau persamaan air tanah yang mengakomodir perubahan massa jenis terhadap ruang dan waktu. Penelitian ini menggunakan persamaan aliran air tanah dependent-density yang pernah dikembangkan oleh Kurnia (2012). Persamaan lain yang diperlukan adalah persamaan transpor adveksidispersi dan gradien perubahan massa jenis terhadap perubahan konsentrasi. Diskritasi persamaan diferensial menggunakan metode Finite-Difference melalui skema Alternating Direction Implicit (ADI). Simulasi model dilakukan dengan menyusun program pada bahasa Visual Basic for Application (Excel-VBA). Model diperlakukan dengan 2 kondisi simulasi yaitu tanpa dan dengan pemompaan akuifer. Hasil akhir simulasi menggambarkan kondisi model sebelum dan setelah intrusi air laut sesuai dengan kodisi teoritisnya.

---

ABSTRACT
Seawater intrusion is one of the groundwater quality problems which can be simulated as a mathematical model. The mathematical model is formulated as the partial differential equation (PDE) and the solution of the PDE is obtained numerically. The Main objective of this research to simulate seawater intrusion phenomena numerically in the confined aquifer. Dependent-density groundwater flow model is necessary to simulate seawater intrusion phenomena. This research employs the dependent-density groundwater flow model which developed by Kurnia (2012). The other equations to complete simulation are advection-dispersion transport model and the gradient of the changes of fluid density to the changes of concentration constituent. Discretization of PDE is conducted using the Finite-Difference method through Alternating Direction Implicit (ADI) scheme. Simulation is conducted by developing computer programming. Visual Basic for Application (Excel-VBA) is chosen for this research. There are 2 conditions of simulation follows without and by pumping aquifer. The final result of simulation describes both of the model condition, before and after pumping aquifer are appropriate to the theoretical condition.

Abstrak :
ABSTRAK
Penelitian ini merupakan penelitian komprehensif menggunakan analisis balik yang dilakukan terhadap settlement preloading dengan pemasangan prefabricated vertical drain (PVD) dengan studi kasus proyek di Gresik, Jawa Timur. Tujuan dari penelitian ini adalah mengetahui faktor yang menyebabkan terjadinya perbedaan settlement pada 16 titik uji settlement plate di lapangan. Metode yang digunakan untuk menganalisis settlement merupakan Metode Kombinasi dan Finite Difference Method dengan menggunakan program CONSOL. Hasil dari penelitian ini menunjukkan bahwa nilai Cv ekuivalen dari seluruh settlement plate bernilai 10-30 kali lipat Cv laboratorium. Nilai Cc hasil pemodelan bernilai 0.5-0.9 dengan rata-rata rasio perbandingan antara Cc pemodelan yang menggambarkan Cc lapangan terhadap Cc laboratorium adalah sebesar 0.66. Rasio tersebut berarti bahwa rata-rata nilai Cc lapangan adalah sebesar 66% dari nilai Cc yang didapatkan dari tes laboratorium. Rasio Cv/Ch yang didapatkan berkisar 0.3-0.67, berarti drainase arah horizontal lebih besar dibandingkan drainase arah vertikal. Hal yang mempengaruhi perbedaan tersebut adalah letak titik pantau, tinggi timbunan, kecepatan penimbunan, dan smear effect. hr> ABSTRACT
This study is a comprehensive study using back analysis conducted on preloading settlement with the installation of prefabricated vertical drain (PVD) with a project case study in Gresik, East Java. The purpose of this study was to determine the factors that cause differences in settlement on settlement plate of 16 field test points. The methods used to analyze the settlement are Combination Method and Finite Difference Method using software CONSOL. The result of this study shows that the value of equivalent Cv is 10-20 times larger than Cv acquired from laboratory test. The value of compression index (Cc) ranged from 0.55-0.9 and the ratio of Cc obtained from modelling which represents actual Cc value in field compared with Cc obtained from laboratory test is 0.66. The ratio shows that Cc obtained in field is 66% of the Cc obtained in laboratory tests. Ratio of Cv/Ch ranged from 0.3-0.67, it shows that radial drainage is larger than vertical drainage. The factors affecting that difference is the location of the observed area, height of embankment, speed of embankment construction, and smear effect

Abstrak :
Pada skripsi ini dibahas tentang diskritisasi model epidemi SVEIR pada transmisi pneumonia dengan intervensi vaksin dan pengobatan (Darmawan, 2022) dengan menggunakan metode beda hingga tak standar (NSFD). Berdasarkan kajian analitik menunjukkan bahwa model NSFD mempunyai dua titik keseimbangan yang jenis kestabilannya bergantung pada angka reproduksi dasar (R0). Kajian analitik juga memperlihatkan bahwa titik keseimbangan bebas penyakit akan bersifat stabil asimtotik ketika R0<1 dan tidak stabil ketika R0>1. Kondisi endemik memiliki keseimbangan hanya ketika nilai R0>1. Kajian numerik dilakukan terhadap model NSFD untuk memperoleh informasi bahwa step-size h=0,1 paling optimal agar dapat memperoleh solusi yang mirip dengan model kontinu. Selain itu, kajian numerik juga dilakukan pada simulasi autonomous dengan mempertimbangkan intervensi vaksin dan pengobatan. Simulasi autonomous menunjukkan hasil bahwa peningkatan laju vaksinasi dan laju pengobatan dapat menekan jumlah individu yang terinfeksi pneumnia. ......This research discusses the discretization of the SVEIR epidemic model of pneumonia transmission with vaccine and treatment interventions (Darmawan, 2022) using the non-standard finite difference method (NSFD). Based an analytical studies showed that the NSFD model has two equilibrium points whose stability depends on the basic reproduction number R0. Analytical studies also show that the disease-free equilibrium point will be asymptotically stable when R0<1 and unstable when R0>1. Endemic condition has an equilibrium only when the value of R0>1. A numerical study as carried out on the NSFD model to obtain information that h=0,1 is an optimal step-size in order to obtain a similar solution to the continuous model. In addition, a numerical studies wee also conducted on autonomous simulation that considers vaccine and treatment interventions. The autonomous simulation shows that increasing the vaccination rate and the treatment rate can reduce the number of pneumonia.

Abstrak :
Pada skripsi ini dibahas tentang diskritisasi model epidemi SVEIR pada transmisi pneumonia dengan intervensi vaksin dan pengobatan (Darmawan, 2022) dengan menggunakan metode beda hingga tak standar (NSFD). Berdasarkan kajian analitik menunjukkan bahwa model NSFD mempunyai dua titik keseimbangan yang jenis kestabilannya bergantung pada angka reproduksi dasar (R0). Kajian analitik juga memperlihatkan bahwa titik keseimbangan bebas penyakit akan bersifat stabil asimtotik ketika R0<1 dan tidak stabil ketika R0>1. Kondisi endemik memiliki keseimbangan hanya ketika nilai R0>1. Kajian numerik dilakukan terhadap model NSFD untuk memperoleh informasi bahwa step-size h=0,1 paling optimal agar dapat memperoleh solusi yang mirip dengan model kontinu. Selain itu, kajian numerik juga dilakukan pada simulasi autonomous dengan mempertimbangkan intervensi vaksin dan pengobatan. Simulasi autonomous menunjukkan hasil bahwa peningkatan laju vaksinasi dan laju pengobatan dapat menekan jumlah individu yang terinfeksi pneumnia. ......This research discusses the discretization of the SVEIR epidemic model of pneumonia transmission with vaccine and treatment interventions (Darmawan, 2022) using the non-standard finite difference method (NSFD). Based an analytical studies showed that the NSFD model has two equilibrium points whose stability depends on the basic reproduction number R0. Analytical studies also show that the disease-free equilibrium point will be asymptotically stable when R0<1 and unstable when R0>1. Endemic condition has an equilibrium only when the value of R0>1. A numerical study as carried out on the NSFD model to obtain information that h=0,1 is an optimal step-size in order to obtain a similar solution to the continuous model. In addition, a numerical studies wee also conducted on autonomous simulation that considers vaccine and treatment interventions. The autonomous simulation shows that increasing the vaccination rate and the treatment rate can reduce the number of pneumonia.

Abstrak :
This book provides a unified and accessible introduction to the basic theory of finite difference schemes applied to the numerical solution of partial differential equations. Originally published in 1989, its objective remains to clearly present the basic methods necessary to perform finite difference schemes and to understand the theory underlying the schemes. Finite Difference Schemes and Partial Differential Equations, Second Edition is one of the few texts in the field to not only present the theory of stability in a rigorous and clear manner but also to discuss the theory of initial-boundary value problems in relation to finite difference schemes. Fourier analysis is used throughout the book to give a unified treatment of many of the important ideas found in the first eleven chapters. The material on elliptic partial differential equations found in the later chapters provides an introduction that will enable students to progress to more advanced texts and to knowledgeably implement the basic methods.

Abstrak :
This book provides an elementary introduction to some one-dimensional fluid flow problems involving shock waves in air. The differential equations of fluid flow are approximated by finite difference equations and these in turn are numerically integrated in a stepwise manner. Artificial viscosity is introduced into the numerical calculations in order to deal with shocks. The presentation is restricted to the finite-difference approach to solve the coupled differential equations of fluid flow as distinct from finite-volume or finite-element methods. This text presents the results arising from the numerical solution using Mathcad programming. Both plane and spherical shock waves are discussed with particular emphasis on very strong explosive shocks in air.

Abstrak :
Deposit paleotsunami telah ditemukan di berbagai lokasi di Indonesia, diantaranya ialah di kawasan Pacitan, Kulon Progo, Cilacap, Pangandaran, serta kawasan Lebak, Banten. Penelitian kali ini dilakukan dengan tujuan untuk mendapatkan model yang ideal dalam penentuan luasan zona inundasi paleotsunami di sepanjang kawasan pesisir selatan Malingping, Kabupaten Lebak, Provinsi Banten dengan metode pemodelan numerik finite difference melalui perangkat lunak ComMIT yang berbasis sistem MOST (Method Of Splitting Tsunamis). Kegiatan lapangan dilakukan guna mengidentifikasi keberadaan endapan paleotsunami pada kawasan lembahan atau swale. Beberapa skenario seperti peristiwa Pangandaran 2006, Aceh 2004, Tohoku 2011, serta gempa yang bersumber pada kawasan segmen megathrust Selat Sunda, dan megathrust sepanjang selatan Jawa digunakan dalam proses pemodelan untuk melihat karakteristik paleotsunami yang paling mungkin mengendapkan deposit di kawasan penelitian. Pemodelan dilakukan dengan berbagai macam skema yaitu dengan memanfaatkan unit source dengan bentuk segmen-segmen pada zona subduksi pada database ComMIT, serta menggunakan parameter sumber gempa yang dimasukkan secara manual untuk selanjutnya dilakukan pemodelan pada ComMIT. Hasil pemodelan menunjukkan skenario tsunami terburuk yang mungkin pernah terjadi di kawasan penelitian ialah peristiwa tsunami dengan nilai magnitudo mencapai 9.1Mw, dengan jangkauan inundasi maksimum sejauh 5,2 kilometer, serta amplitudo gelombang mencapai 32 meter, yang diperkirakan menjadi peristiwa tsunami yang mengendapkan deposit paleotsunami yang ditemukan di daerah penelitian. ......Paleotsunami deposits have been found in various locations in Indonesia, such as in the Pacitan area, Kulon Progo, Cilacap, Pangandaran, and Lebak, Banten. This research was conducted with the aim of obtaining an ideal model in determining the area of the paleotsunami inundation zone along the southern coastal area of Malingping, Lebak Regency, Banten Province with the finite difference numerical modeling method through ComMIT software based on the MOST (Method Of Splitting Tsunamis) system. Field activities were carried out to identify the presence of paleotsunami deposits in the swale area. Several scenarios such as the Pangandaran 2006, Aceh 2004, Tohoku 2011, as well as earthquakes originating in the Sunda Strait megathrust segment area, and megathrust along the south of Java were used in the modeling process to see the characteristics of paleotsunami that were most likely to produced the tsunami deposits in the study area. Modeling is carried out with various schemes, such as using the ComMIT database unit source in the form of segments in the subduction zone, as well as using earthquake source parameters that are entered manually for further modeling on ComMIT. The modeling results show that the worst tsunami scenario that may have ever occurred in the study area is the tsunami event with a magnitude value of 9.1Mw, with a maximum inundation range of 5.2 kilometers, and a wave amplitude of up to 32 meters, which is estimated to be a tsunami event that deposits paleotsunami deposits found in the study area.