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Journal : Journal of Engineering and Technological Sciences

Three-dimensional DC Resistivity Modeling using Galerkin Finite Element Method Composed by Tetrahedral Elements Srigutomo, Wahyu; Anwar, Hairil; Agustine, Eleonora; Mahardika, Harry
Journal of Engineering and Technological Sciences Vol 51, No 4 (2019)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (768.912 KB) | DOI: 10.5614/j.eng.technol.sci.2019.51.4.5

Abstract

Successful interpretation of DC resistivity data depends on the availability of a proper forward modeling scheme. In this study, a three-dimensional DC resistivity forward modeling scheme was developed using the finite element method. The finite element equations were obtained using a weakened form of the weighted-residual method called the Galerkin method. Discretization of the modeling domain was carried out by dividing it into smaller three-dimensional blocks and subdividing each block into five tetrahedral elements. A linear interpolation function was employed and elemental linear equations were set up, followed by formation of global matrix systems of equation and incorporation of proper boundary conditions. The conjugate gradient method was applied to solve the global system of equations, which in this study was proven to be more efficient than a direct solver, contributing to a 67% time reduction. Using a Wenner array configuration, comparison with theoretical calculation of the electric potential for a homogeneous model yielded a relative error of 3.66%. To confirm the applicability of this forward modeling scheme, apparent resistivity profiles for several basic three-dimensional subsurface resistivity models were compared with the analytical profiles, yielding an acceptable level of fitting.
Three-dimensional DC Resistivity Modeling using Galerkin Finite Element Method Composed by Tetrahedral Elements Wahyu Srigutomo; Hairil Anwar; Eleonora Agustine; Harry Mahardika
Journal of Engineering and Technological Sciences Vol. 51 No. 4 (2019)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2019.51.4.5

Abstract

Successful interpretation of DC resistivity data depends on the availability of a proper forward modeling scheme. In this study, a three-dimensional DC resistivity forward modeling scheme was developed using the finite element method. The finite element equations were obtained using a weakened form of the weighted-residual method called the Galerkin method. Discretization of the modeling domain was carried out by dividing it into smaller three-dimensional blocks and subdividing each block into five tetrahedral elements. A linear interpolation function was employed and elemental linear equations were set up, followed by formation of global matrix systems of equation and incorporation of proper boundary conditions. The conjugate gradient method was applied to solve the global system of equations, which in this study was proven to be more efficient than a direct solver, contributing to a 67% time reduction. Using a Wenner array configuration, comparison with theoretical calculation of the electric potential for a homogeneous model yielded a relative error of 3.66%. To confirm the applicability of this forward modeling scheme, apparent resistivity profiles for several basic three-dimensional subsurface resistivity models were compared with the analytical profiles, yielding an acceptable level of fitting.
Global Inversion of Grounded Electric Source Time-domain Electromagnetic Data Using Particle Swarm Optimization Cahyo Aji Hapsoro; Wahyu Srigutomo; Acep Purqon; Warsa warsa; Doddy Sutarno; Tsuneomi Kagiyama
Journal of Engineering and Technological Sciences Vol. 53 No. 1 (2021)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2021.53.1.1

Abstract

Global optimization inversion of grounded wire time-domain electromagnetic (TDEM) data was implemented through application of the particle swarm optimization (PSO) algorithm. This probabilistic approach is an alternative to the widely used deterministic local-optimization approach. In the PSO algorithm, each particle that constitutes the swarm epitomizes a probable geophysical model comprised by subsurface resistivity values at several layers and layer thicknesses. The forward formulation of the TDEM problem for calculating the vertical component of the induced magnetic field is first expressed in the Laplace domain. Transformation of the magnetic field from the Laplace domain into the time domain is performed by applying the Gaver-Stehfest numerical method. The implementation of PSO inversion to the TDEM problem is straightforward. It only requires adjustment of a few inversion parameters such as inertia, acceleration coefficients and numbers of iteration and particles. The PSO inversion scheme was tested on synthetic noise-free data and noisy synthetic data as well as to field data recorded in a volcanic-geothermal area. The results suggest that the PSO inversion scheme can effectively solve the TDEM 1D stratified earth problem. 
Curie Point Depth Analysis of Lesugolo Area, East Nusa Tenggara, Indonesia Based on Ground Magnetic Data Alamta Singarimbun; Umar Said; Dini Andriani; R. B. Astro; Bakrun Bakrun; I G. P. F. Soerya Djaja; Eleonora Agustine; Pepen Supendi; Wahyu Srigutomo
Journal of Engineering and Technological Sciences Vol. 54 No. 1 (2022)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2022.54.1.11

Abstract

The Curie point depth, or magnetic basal depth, of the Lesugolo geothermal area in Ende, Flores Island, East Nusa Tenggara, Indonesia was estimated by performing spectral analysis on spatial magnetic data and transforming it into the frequency domain, resulting in a link between the 2D spectrum of magnetic anomalies and the depths of the top and centroid of the magnetic sources. Shallow Curie point depths of 16 to 18 km were found in the north-northeast to southeast areas of Lesugolo, while deeper depths of 24 to 26 km were found in the southwest. The tectonic setting beneath the central part of Flores Island governs the distribution of the Curie point depths in the area. Shallow Curie point depth zones are associated with high thermal gradients (30 to 34 °C/km) and heat flow (80 to 100 mW/m2). Deep depths, on the other hand, correspond to zones of low thermal gradient (21 to 26 °C/km) and low heat flow (65 to 80 mW/m2). Both the derived thermal gradient and the heat flow maps contribute to a better understanding of the Lesugolo geothermal system’s configuration. This study suggests that the Lesugolo geothermal area’s prospect zone is located in the center of the investigated area, where the Lesugolo normal fault forms its southeastern boundary.
Examining External Dose Rates in Mamuju Regency, Indonesia: A Personal Radiation Dosimetry Approach Rakotovao Lovanantenaina Omega; Adi R.A. Abdullah; Sidik Permana; Wahyu Srigutomo; Alan Maulana; Haryo Seno; Ismail Humolungo; Fungki Iqlima Nasyidiyah; Zulfahmi Zulfahmi; Frafti Rejeki; Rahmi Elzufiah
Journal of Engineering and Technological Sciences Vol. 55 No. 6 (2023)
Publisher : Directorate for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2023.55.6.6

Abstract

This study aimed to quantify the individual external radiation exposure in Mamuju, Indonesia. A SmartRad portable personal dosimeter was utilized for this purpose, and data was collected over a period of 30 days. The findings indicate that the dose rate varies from 0.152 to 4.200 μSv/h and cumulatively ranges from 0.1 to 8.4 μSv/day based on an average measurement duration of 160 minutes. The average dose rate in areas with mineral deposits is 11.02 mSv per year. In contrast, the average effective dose in areas without radioactive mineral deposits is 2.6493 mSv per year. The annual average effective dose for individuals was measured at 6.8347 mSv. These findings imply that personal exposure to radiation among the public in Mamuju exceeds the threshold recommended by the International Commission of Radiological Protection.
Co-Authors Abdullah, Adi Rahmansyah Amir Acep Purqon Acep Purqon Adam Sukma Putra Adhitya S. Sunarya Adi R.A. Abdullah Alamta Singarimbun Alan Maulana Alan Maulana Alief Sadlie Kasman Anggie Susilawati Anwar, Hairil Ari Setiawan Arizal Akbar Zikri Asep Harja Asep Harja Asep Saefullah Azrul Azwar Bakrun Bakrun Candra E. Novana Deny Juanda Puradimaja Dini Andriani Dini Fitriani Doddy Sutarno Doddy Sutarno Doddy Sutarno Doddy Sutarno Doddy Sutarno Doddy Sutarno Eddy Supriyana Eleonora Agustine Eleonora Agustine Eleonora Agustine Eleonora Agustine Enjang Jaenal Mustopa Enjang Jaenal Mustopa Enjang Jaenal Mustopa Fajriani Fajriani Fajriani Fajriani Fariduzzaman Fariduzzaman Fourier Dzar Eljabbar Latief Frafti Rejeki Fungki Iqlima Nasyidiyah Ghany Hanifan Muslim Hairil Anwar Hairil Anwar Hairil Anwar Halawa Ernwati Hapsoro, Cahyo Aji Harapan Marpaung Hardi Hamzah Harry Mahardika Haryo Seno Hendra Gunawan Herlan Darmawan Herlin Tarigan Hisashi Utada Humolungo, Ismail Husnul Hamdi Husnul Hamdi, Husnul I G. P. F. Soerya Djaja I Gede Putu Fadjar Soerya Djaja Imam Suyanto Imran Hilman Mohammad Imran Hilman Mohammad Irwan Ary Darmawan irwan meilano Irzaman, Irzaman Ismail Humolungo Jayawarsa, A.A. Ketut Joko Sampurno Kartika Hajar Kirana Kumalasari, Ratih Kuncoro, Alvina Kusumadewi Linus Pasasa M. Habri Zen Mahardika, Harry Maria Evita Martin Liess Martin Liess Melany Febrina Mitra Djamal Moh Yasin Mohammad Heriyanto Mohammad Heriyanto Muhamad Hilmi Aufa Muhammad Abdilllah Budianto Nadhira Gunawan Ni Ketut Lasmia Nina Siti Aminah Pepen Supendi Pratomo, Prihamdhanu Mukti Prihamdhanu Mukti Pratomo Prihandhanu M. Pratomo Purnama, Dikdik Sidik Putra, Heriansyah Rahmi Elzufiah Rakotovao Lovanantenaina Omega Rasito Tursinah, Rasito RATIH KUMALASARI Ratih Kumalasari Retna Apsari Richardo Barry Astro Rifky Nauval Rostikwati, Diana Ayu Ruddy Kurnia Satria, Eko Seno, Haryo Sesri Santurima Setyanto Cahyo Pranoto Sidik, Adi Permana Sitti Balkis Sparisoma Viridi Sumintadireja, Prihadi Suprijadi Suprijadi Suprijadi Suprijadi Supriyadi Supriyadi Surya Ningsih Surya Ningsih Suryanto, Wiwit Tsuneomi Kagiyama Tsuneomi Kagiyama Tsuneomi Kagiyama UMAR FAUZI Umar Fauzi Umar Said Wahyu Hidayat Wahyudi Wahyudi Warsa warsa Wataru Kanda Yanti Yanti Yazid Bindar Yuant Tiandho Zulfahmi Zulfahmi Zulfahmi Zulfahmi Zulhendra Zulhendra