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Zulhendra Zulhendra
Universitas Negeri Padang
Agriculture, Biological Sciences & Forestry Astronomy Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Education Electrical & Electronics Engineering Energy Engineering Environmental Science Materials Science & Nanotechnology Mathematics Mechanical Engineering Physics Social Sciences Other

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Inert Gas Axial Flow Analysis on Thermal System with Natural Convection Condition Rio Anshari; Mairizwan Mairizwan; Fandi Oktasendra; Debi Rianto; Zulhendra Zulhendra
EKSAKTA: Berkala Ilmiah Bidang MIPA Vol. 24 No. 01 (2023): Eksakta : Berkala Ilmiah Bidang MIPA (E-ISSN : 2549-7464)
Publisher : Faculty of Mathematics and Natural Sciences (FMIPA), Universitas Negeri Padang, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/eksakta/vol24-iss01/338

Abstract

The Fukushima nuclear accident in 2011 became the basis for consideration of the use of gas as a coolant in nuclear reactors. This is because the convection rate of gas flow in the cooling channel can occur naturally due to differences in density and does not require the help of a pumps for the circulation of the coolant. This study aims to analyze how the flow pattern of an inert gas on a vertical-axial reference by natural convection in a thermal system. The focus of this research is to study the flow parameters of the coolant with a gas phase. This research is an experimental study. The analysis was carried out using a descriptive approach and computer simulation-assisted numerical analysis methods. The results showed that the distribution and variation of heat was radially dominant in the middle so that the coolant channel wall received less heat load. The magnitude of the pressure drop along the vertical-axial channel shows a homogeneous pattern and decreases radially from center to edge. These results indicate the use of inert gas as a coolant can be considered as an alternative coolant in heat systems that do not depend on pumps in operating conditions.
Analisis Kebutuhan Pengembangan Bahan Ajar Digital Fisika Berbasis Project Based Learning Terintegrasi Pendekatan STEM Selma Riyasni; Intan Purnama Yani; Widia Kemala Sari; Zulhendra Zulhendra
Journal on Education Vol 6 No 1 (2023): Journal On Education: Volume 6 Nomor 1 Tahun 2023
Publisher : Departement of Mathematics Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31004/joe.v6i1.3775

Abstract

21st century learning is suggested to be based on information and communication technology, for example using digital teaching materials. The learning model used is an innovative learning model that improves students' 21st century skills such as project based learning which is also suggested in the independent curriculum. The use of project based learning learning models is considered effective if it integrates the STEM approach. The initial step in developing STEM-integrated PjBL-based digital teaching materials is to conduct an analysis of the needs of teachers and students. The purpose of this study is to describe the results of the analysis of the needs for the development of digital teaching materials based on the integrated PjBL learning model with the STEM approach. The subjects of this study were 22 physics teachers and 50 students of SMAN 2 Bukittinggi. Data collection through questionnaires, then analyzed to obtain conclusions. The conclusions from this study show 1) learning still does not use digital teaching materials, 2) it is necessary to develop teaching materials based on the PjBL learning model that is integrated with STEM to assist student project assignments.
SEISMIC RATE CHANGES ANALYSIS BASED ON THE SPASIAL DISTRIBUTION SEISMOTECTONICS IN THE SOUTHERN SUMATRA REGION Florentina Simalango, Nora; Syafriani, Syafriani; Dwiridal, Letmi; Zulhendra, Zulhendra
JOURNAL ONLINE OF PHYSICS Vol. 10 No. 1 (2024): JOP (Journal Online of Physics) Vol 10 No 1
Publisher : Prodi Fisika FST UNJA

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22437/jop.v10i1.38137

Abstract

The southern Sumatra region experiences high seismic activity, often resulting in large earthquakes that cause significant losses. Before such earthquakes, a phenomenon known as seismic quiescence a decrease in seismic activity commonly occurs. This phenomenon can be analyzed through changes in seismic rates using the spatial distribution of Z-values. This study investigates the occurrence of seismic quiescence before major earthquakes and examines changes in seismic rates in southern Sumatra. Used secondary earthquake data from the United States Geological Survey (USGS) for 1973–2023 were analyzed, focusing on the region between 2.050°S–5.885°S and 101.030°E–106.611°E. The study centered on three significant earthquakes: the 2000 (7.9 Mw), 2001 (7.4 Mw), and 2007 (8.4 Mw) events.  Seismic rate changes were analyzed using the Z-value method, dividing the region into grids to calculate and spatially distribute Z-values. Results showed seismic quiescence before the 2000 (±16 years), 2001 (±13 years), and 2007 (±17 years) earthquakes in Bengkulu. Additionally, similar phenomena were observed in Bengkulu and Lampung before 2023, suggesting the potential for future significant earthquakes in the region. These findings highlight seismic quiescence as a precursor to major seismic events.
Analysis Of Seismic Rate Change Based On Spatial Distribution Of Seismotectonics And Deformation Extension In West Nusa Tenggara Aprimanda Mulya Rizki, Rifa; Syafriani; Amir, Harman; Zulhendra, Zulhendra
Jurnal Pendidikan, Sains, Geologi, dan Geofisika (GeoScienceEd Journal) Vol. 6 No. 1 (2025): Februari
Publisher : Mataram University

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Abstract

Wilayah Nusa Tenggara Barat memiliki aktivitas kegempaan yang tinggi. Sebelum terjadinya suatu kejadian gempa bumi, terlebih dahulu didahului oleh keadaan seismik tenang. Tujuan dari penelitian ini untuk mengetahui perubahan laju seismik yang diamati dari fenomena seismik tenang dan luas deformasi. Metode perubahan laju seismik yang digunakan adalah distribusi spasial z-value. Dan metode luas deformasi yang digunakan adalah rumusan Utsu dan Seki untuk gempa bumi M7,0 pada tanggal 5 Agustus 2018 dengan input magnitudo permukaan. Penelitian ini menggunakan data dari website USGS periode 1983-2023. Pada penelitian ini terdapat tiga zona fokus penelitian yaitu gempa bumi tahun 2009 (M6,6), gempa bumi tahun 2018 (M7,0) dan gempa bumi tahun 2018 (M6,9). Dengan menggunakan metode distribusi spasial z-value, wilayah dibagi menjadi beberapa grid. Nilai z dihitung pada setiap grid dan menggambarkan perubahan laju seismik. Fenomena tersebut dapat dilihat berdasarkan perubahan laju seismik yang telah diperoleh. Hasil yang diperoleh, pada zona pertama terjadi peningkatan aktivitas seismik sebelum gempa bumi 2009, zona kedua dan zona ketiga terjadi fenomena seismic quiescence yang mendahului gempa bumi 2018. Berdasarkan sebaran spasial z-value awal tahun 2023, terjadi fenomena penurunan aktivitas seismik di sebagian wilayah Nusa Tenggara Barat. Serta terjadi deformasi sebesar 1.091,44 km2 pada gempa bumi M7,0 tanggal 5 Agustus 2018. Hal ini patut diduga sebagai awal gejala gempa bumi di masa mendatang .
Analysis Of Seismic Quiescence Precursors Before The M7.4 Earthquake Of 28 September 2018 In Central Sulawesi Based On Seismotectonic Spatial Distribution And Earthquake Fracture Lengths zu, Zurahma; Syafriani; Dwiridal, Letmi; Zulhendra, Zulhendra
Jurnal Pendidikan, Sains, Geologi, dan Geofisika (GeoScienceEd Journal) Vol. 6 No. 1 (2025): Februari
Publisher : Mataram University

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Abstract

The Central Sulawesi earthquake with coordinates 2°30‘S -1°50’ N and 119°0'-124°20 E magnitude 7.4 in Palu, Donggala Regency on 28 September 2018. This earthquake was a significant and destructive earthquake in Central Sulawesi. A significant earthquake is preceded by a seismic quiescence. The aim of the study was to determine when the seismic quiescence occurred and seismic activity after the earthquake alongside fracture length. The method of analysis of seismic quiescence and fracture length is z-value and Wells and Coppersmith equation. Data processed with MATLAB and Zmap were 1478 events from 1983-2023. The study area is divided into several grids with sizes of 0.1°* 0.1°. The number of earthquakes included (N = 800, 700, 600, 500, 400, 300, and 200). The z-value was calculated for each grid based on the earthquake data organized in one grid and seismic activity after earthquake. The results of the analysis of the z-value calculation in each grid show of seismic quiescence before a significant earthquake. Based on the results of the spatial distribution of z-value in Central Sulawesi, the seismic quiescence preceded the 28 September 2018 earthquake event (M 7.4) by about 21 years beginning in 1990. When cut at 2019.6, there was a decrease in seismic activity again, which indicated that an earthquake would occur, so it was thought to be a trigger factor for future earthquake precursors. While the fracture length of the 7.4 Mw earthquake of 104,232 meters shows a positive correlation between magnitude and fracture length.
Estimation Of Maximum Ground Acceleration Value Based On Mentawai Earthquake Scenario Using Atkinson Boore and Zhao Khairunnissa, Shafira; Syafriani; Fauzi, Ahmad; Zulhendra, Zulhendra
Jurnal Pendidikan, Sains, Geologi, dan Geofisika (GeoScienceEd Journal) Vol. 5 No. 4 (2024): November
Publisher : Mataram University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29303/goescienceed.v5i4.510

Abstract

We have estimated the value and intensity of maximum ground acceleration in West Sumatra based on the Mentawai earthquake scenario by using the formulation of Atkinson Boore (2003) and Zhao (2006). This study aims to determine the PGA value of an area as the level of activity and intensity of the earthquake in West Sumatra region from the Mentawai earthquake scenario as a measure of damage caused by the earthquake and analyze its distribution. This study uses earthquake information data for the period 1900-2023 with magnitude > 7 SR and depth < 100 km and shear wave velocity model at a depth of 30 meters (Vs 30) sourced from the National Earthquakes Information Center US Geological Survey (NEIC/USGS) catalog. After that, calculations are carried out so that the estimated maximum ground acceleration value is obtained using the Atkinson Boore (2003) and Zhao (2006) formulas. The maximum ground acceleration and earthquake intensity values for each city/regency in West Sumatra were calculated with a 0.1° grid. The estimation results show that the largest values for each scenario are in Mentawai Islands and South Pesisir because those areas are close to the subduction zone. In addition, it is also influenced by the epicenter, magnitude and soil type in the region. So that the maximum ground acceleration value in West Sumatra ranges from 0.007 g - 2.117 g with earthquake intensity ranging from I - X+ MMI. This indicates that the area is vulnerable to damage if an earthquake occurs. Keywords: Earthquakes, Atkinson Boore, Zhao, PGA, Intensity
Pengaruh ENSO dan IOD Terhadap Curah Hujan di Indonesia Fadila, Husnul; Yendri Sudiar, Nofi; Razi, Pakhrur; Zulhendra, Zulhendra
Jurnal Pendidikan Tambusai Vol. 9 No. 1 (2025)
Publisher : LPPM Universitas Pahlawan Tuanku Tambusai, Riau, Indonesia

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Abstract

Penelitian ini memiliki tujuan untuk mengkaji pengaruh fenomena ENSO (El Niño Southern Oscillation) dan IOD (Indian Ocean Dipole) terhadap pola curah hujan di Indonesia. Fenomena ENSO dan IOD dipengaruhi oleh perubahan suhu permukaan laut, dengan IOD terjadi di wilayah tropis Samudra Hindia dan El Niño-La Niña di Samudra Pasifik. Data yang digunakan dalam studi ini mencakup Indeks Niño 3.4, Indeks Dipole Mode, serta data curah hujan. Hasil penelitian menunjukkan bahwa di stasiun dengan tipe curah hujan monsun, seperti Bali dan Jawa Timur, terdapat korelasi signifikan dengan kategori rendah dan sangat rendah. Di stasiun dengan tipe curah hujan ekuatorial, seperti Sumatra Barat dan Kalimantan Barat, korelasi yang ditemukan ada yang signifikan dan ada yang tidak, dengan kategori rendah dan sangat rendah. Hal serupa juga ditemukan pada stasiun dengan tipe curah hujan lokal, seperti Maluku dan Papua.
Pengaruh Volatile Organic Compounds(VOC) dan Radiasi Matahari terhadap Konsentrasi Ozon Permukaan di Bukit Kototabang Bukittinggi Bahri, Aliefa Zunaida; Sudiar, Nofi Yendri; Razi, Pakhrur; Zulhendra, Zulhendra
Jurnal Pendidikan Tambusai Vol. 9 No. 1 (2025)
Publisher : LPPM Universitas Pahlawan Tuanku Tambusai, Riau, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31004/jptam.v9i1.25480

Abstract

Penelitian ini akan menganalisis secara mendalam bagaimana senyawa organik volatil (Volatile Organic Compounds/VOC) dan radiasi matahari terhadap konsentrasi ozon permukaan di Stasiun GAW Bukit Kototabang, Bukittinggi. Data VOC meliputi etanol dan propanol, serta data intensitas radiasi matahari, dianalisis sebagai variabel independen yang memengaruhi pembentukan ozon permukaan melalui reaksi fotokimia. Metode yang di implementasikan dalam analisis ini adalah regresi linier berganda untuk memahami kekuatan hubungan antarvariabel dan tingkat kontribusi masing-masing variabel terhadap konsentrasi ozon permukaan. Hasil penelitian menunjukkan bahwa VOC dan radiasi matahari berkontribusi positif terhadap peningkatan konsentrasi ozon permukaan, dengan intensitas maksimum terjadi pada siang hari. Secara statistik, analisis regresi menunjukkan nilai R-squared sebesar 79%, yang mengindikasikan bahwa kombinasi radiasi matahari dan konsentrasi VOC dapat menjelaskan sebagian besar variasi ozon permukaan di lokasi penelitian. Namun, yang tersisa senilai 21% mungkin dipengaruhi oleh variabel eksternal yang tidak dikaji dalam penelitian ini, seperti kelembapan udara, suhu, dan emisi dari sumber antropogenik lainnya.
Estimation of Earthquake Intensity and Peak Ground Acceleration in West Java Using the MC Guire and the Lin & Lee Method Resi Silvianis; Syafriani; Letmi Dwiridal; Zulhendra
Kappa Journal Vol 8 No 3 (2024): Desember
Publisher : Universitas Hamzanwadi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29408/kpj.v8i3.28095

Abstract

Abstract:  West Java province was in a subduction zone and fault zone (slip fault), which caused earthquakes. Therefore, it was necessary to research estimates of maximum ground acceleration in West Java to mitigate earthquake disasters. This research also aimed to determine the value of ground acceleration and earthquake intensity and to determine the distribution map using the McGuire method and the Lin & Lee method. The data used were earthquake data for 1950-2023 with a magnitude > 5 SR. From processing this data, the maximum ground acceleration value in West Java ranged between 10.14722-195.3540 gal, and the maximum intensity value was IV-VI MMI using the Mc Guire method. Meanwhile, for the Lin & Lee method, it ranged between 6.6512 to 49.24599 gal. Of the two methods, the largest maximum ground acceleration value was located in Cianjur Regency, which was due to its proximity to the Cimandiri fault and the geological conditions in the area.
Subsurface Lithology Analysis Using HVSR Method in Jorong Ranah, X Koto Singkarak District Althaf, Muhammad Mahdy; Syafriani, Syafriani; Zulhendra, Harman Amir
Jurnal Pendidikan, Sains, Geologi, dan Geofisika (GeoScienceEd Journal) Vol. 6 No. 2 (2025): May
Publisher : Mataram University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29303/goescienceed.v6i2.818

Abstract

Jorong Ranah bordered Sumani segment and the Sianok segment. Both of these segments had experienced demaging earthquakes that affected Jorong Ranah. The damage caused could be determined by analyzing the subsurface lithology. This study aimed to determine the value of dominant frequency (f0) and amplification factor (A0) as well as the shear wave velocity (Vs) and subsurface lithology. Microtremor research was conducted at 8 measurement points. Microtremor signals were analyzed using the HVSR method to obtain data in the form of f0 and A0 presented in the form of H/V curves. The values were analyzed using Easy HVSR software to obtain a curve of shear wave velocity values against depth. 2D modeling of subsurface lithology was conducted using Rockworks software. The results showed that the f0 value in Jorong Ranah ranged from 1.25 - 14.75 Hz and the A0 value ranged from 3.26 - 6.92. The shear wave velocity (Vs) values ranged from 100 m/s - 1,604 m/s at depths ranging from 0 - 116.67 meters. In the first layer, the dominating subsurface lithologies were silt, hard sandy loam, breccia tuff, red soil, and gracefully sandstone. In the second layer, the dominating subsurface lithologies were silt, hard sandy loam, tuff, and volcanic breccia. In the third layer, the dominating subsurface lithologies were red soil, volcanic breccia, tuff, and tuff breccia. And in the fourth layer, the dominating subsurface lithologies were red soil and tuff breccia. Subsurface lithology affected potential damage, with high shear wave velocity (Vs) indicating stable, dense rocks and lower damage potential, while low Vs values suggested soft rocks that were more prone to deformation and higher damage risk.
Co-Authors AA Sudharmawan, AA Althaf, Muhammad Mahdy Aprimanda Mulya Rizki, Rifa Bahri, Aliefa Zunaida Debi Rianto Denandra, Alza Fadila, Husnul Fandi Oktasendra Fauzi Ahmad Muda Florentina Simalango, Nora Hamdi Hamdi Handayani, Silvia Sri Hapsoro, Cahyo Aji Harman Amir Intan Purnama Yani Janna, Anisa Khairunnissa, Shafira Letmi Dwiridal Mairizwan Mairizwan Nofi Yendri Sudiar Pakhrur Razi Rahmadhani, Annisa Resi Silvianis Rio Anshari Riyasni, Selma Salsabila, Salsabila Saqilah, Alya Syafriani Syafriani Syafriani, Syafriani Wahyu Srigutomo Widia Kemala Sari Yendri Sudiar, Nofi Zatil Ismah, Amirah Zikri, Ahmad Raihan zu, Zurahma