Jurnal Ilmu Fisika (JIF)
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Equilibrium Points and Periodic Orbits of Artificial Satellite Adjacent to an Oblate and Rotating Asteroid
Full text linkAsteroids have various shapes (mostly irregular) and physical characteristics. Space missions to asteroids are becoming frequent, and a global mapping scheme is applied to collect the asteroids’ physical properties. Depending on the mission purposes, the mapping scheme can encircle the whole asteroid’s body or utilize the asteroid’s equilibrium points for the least energy consumption. Furthermore, it is essential to construct optimal trajectories to maximize the coverage and science results. Thus, an efficient mission can be achieved by devoting periodic orbits of artificial satellites around the equilibria. This study aims to construct periodic orbits related to the equilibria of an oblate shape and rotating asteroid, under the influences of gravitational and rotational potentials. Equations of motion of the satellite affected by the potentials are formulated in the Cartesian coordinate system. By acquiring mutual zero accelerations (first derivative of the potentials with respect to all directions), the equilibria are then obtained. Adjacent to the asteroid, four equilibria were revealed, and analysis of their stability showed that all of them are unstable. Despite this, some periodic orbits centered at the respective equilibria were successfully constructed using some arbitrary parameters (harmonics) that affect the coverage area for mapping the asteroid
Evaluasi Kecepatan Gelombang Geser Tanah Berbasis Data Mikrotremor di Kawasan Karst Rammang-Rammang Maros TN Babul
No full textThis study aims to identify the profile of shear wave velocity (Vs30) and to analyze the classification of soil types of the Rammang-Rammang Maros Karst Area based on Vs30 value. This research was carried out at Rammang-Rammang Maros Karst Area, Salenrang and Bontolempangan Village, Bontoa District, Maros Regency, South Sulawesi. The method used in this research was the Horizontal to Vertical Spectral Ratio (HVSR) method to produce the HVSR curve and then analysed in the inversion method using Dinver to produce a ground profile. The Vs30 values were obtained in the range from 249 to 1384 m/s. The characteristics of the rock response could indicate the specifications of a rock type. Based on the Vs30 values, it was found that the classification of rock (SB) located around the karst hilly areas, soft rock (SC) located around the residential areas and the river, and stiff soil (SD) located near ricefield. The overall seismic risk in the research area is low based on Vs30 values below 200 m/s. These findings provide essential baseline data to support sustainable land use and tourism development planning in the region.Penelitian ini bertujuan untuk mengidentifikasi profil kecepatan gelombang geser tanah (Vs30) dan menganalisis klasifikasi jenis tanah di Kawasan Karst Rammang-Rammang Maros berdasarkan nilai Vs30. Penelitian ini dilakukan di Kawasan Karst Rammang-Rammang Maros, Desa Salenrang dan Desa Bontolempangan, Kecamatan Bontoa, Kabupaten Maros, Sulawesi Selatan. Data mikrotremor dianalisis menggunakan metode HVSR untuk mendapatkan kurva H/V yang merepresentasikan frekuensi dominan dan nilai amplifikasi. Kurva H/V akan dianalisis untuk menghasilkan inversi HVSR yang menunjukkan profil tanah berdasarkan kecepatan gelombang geser. Nilai Vs30 yang diperoleh berkisar antara 249,28 hingga 1384,03 m/s. Respon batuan terhadap getaran gelombang seismik yang melewatinya akan berbeda-beda tergantung dari jenis batuannya. Karakteristik respon batuan dapat mengindikasikan spesifikasi jenis batuan. Berdasarkan nilai Vs30 yang diperoleh, dapat dianalisa bahwa jenis tanah pada lokasi penelitian termasuk dalam klasifikasi tanah keras (SC II), tanah sedang (SC III), dan terdapat satu titik yang termasuk dalam klasifikasi sebagai batuan (SC I)
Effect of Cesium Iodide (CsI) Concentration Variation on the Performance of MethylAmmonium Lead Iodide (MAPbI₃)-based Perovskite Solar Cells
Full text linkThe fabrication of MAPbI3 perovskite solar cell (PSC) devices with the modification of adding cesium iodide (CsI) into the PbI2 layer to enhance performance has been successfully carried out. The used synthesis method was a two-step spin coating with CsI concentration variations: without CsI (control), 2 mg/mL, 3 mg/mL, and 5 mg/mL. Characterization using UV-vis, FESEM, and XRD showed improved in optical properties, morphology, and crystal stability. The UV-Vis spectrum indicated an increase in absorption from 2.29 to 3.17 a.u after CsI addition. FESEM results revealed that a 3 mg/mL CsI concentration produced a uniform morphology, a more compact film layer, and clear grain boundaries compared to other concentrations. XRD analysis showed a 2θ peak shift of 0.04°, indicating changes in crystal lattice parameters and increased lattice density without altering MAPbI₃ crystallinity. The device with 3 mg/mL CsI achieved an open-circuit voltage (Voc) of 1.2 V, a short-circuit current density (Jsc) of 11.34 mA/cm², a fill factor (FF) of 0.65, a power conversion efficiency (PCE) of 2.8%. In conclusion, 3 mg/mL CsI successfully enhanced PSC performance, but performance declined to 5 mg/mL.Pembuatan perangkat perovskite solar cell (PSC) MAPbI3 dengan modifikasi penambahan cesium iodida (CsI) ke dalam lapisan PbI2 untuk meningkatkan kinerja sel surya perovskite telah berhasil dilakukan. Metode sintesis yang digunakan adalah spin coating dua langkah dengan variasi konsentrasi CsI: tanpa CsI (kontrol), 2 mg/mL, 3 mg/mL dan 5 mg/mL. Karakterisasi menggunakan UV-Vis, FESEM, dan XRD menunjukkan peningkatan pada sifat optik, morfologi, dan stabilitas kristal. Spektrum UV-Vis menunjukan peningkatan penyerapan dari 2,29 menjadi 3,17 a.u setelah penambahan CsI. Hasil FESEM menunjukkan bahwa konsentrasi CsI 3 mg/mL menghasilkan morfologi yang seragam, lapisan film yang lebih kompak, dan batas butir yang jelas dibandingkan konsentrasi lainnya. Hasil XRD menunjukkan pergeseran puncak 2θ sebesar 0,04°, yang mengindikasikan perubahan parameter kisi kristal dan peningkatan kerapatan kisi, tanpa mengubah kristalinitas MAPbI3. Kinerja perangkat dengan penambahan CsI 3 mg/mL menghasilkan tegangan rangkaian terbuka (Voc) sebesar 1,2 V, rapat arus hubung singkat (Jsc) sebesar 11,34 mA/cm², faktor pengisian (FF) sebesar 0,65%, efisiensi konversi daya (PCE) sebesar 2,8%. Kinerja perangkat dengan CsI 3 mg/mL mampu mempertahankan 89,29% efisiensi awal setelah 96 jam pengujian tanpa enkapsulasi. Sebagai kesimpulan, penambahan CsI dengan konsentrasi 3 mg/mL berhasil meningkatkan kinerja perangkat PSC MAPbI3, namun kinerja menurun pada konsentrasi 5 mg/m
Efek Surfaktan pada Stabilitas Nanofluid Nickekl Ferrite
No full textNanofluid stability is a critical factor for the effective application of nanofluids in various fields. One simple and effective method to enhance nanofluid stability is through the addition of surfactants. This study examines the effect of different surfactants on the stability of nickel ferrite (NiFe₂O₄)/water nanofluid. The nanofluids were synthesis using the two-step method, and the surfactants investigated inculded oleic acid, polyethylene glycol 400, tetrabutylammonium bromide, gum arabic, and citric acid. Different concentrations for each surfactant were tested by adjusting the nanoparticles-to-surfactant ratio. The suspension stability was evaluated through visual observation, Zeta potential measurements, and thermal conductivity analysis. The most stable NiFe₂O₄/water nanofluid was achieved using citric acid surfactant, with a nanoparticles-to-surfactant volume ratio of 1:0.25, a Zeta potential value of -35.0 mV and an average thermal conductivity of 0.585 ± 0.007 W/m·K. The results of this study are important for developing nanofluid and magnetic nanofluid systems with optimum conductive heat transfer performance.Stabilitas nanofluid merupakan hal penting untuk aplikasi nanofluida dalam berbagai bidang. Metode yang simpel untuk meningkatkan stabilitas nanofluid yaitu dengan penambahan surfaktan. Penelitian ini bertujuan mempelajari variasi surfaktan pada stabilitas nanofluida berbasis air dengan dopan nickel ferrite (NiFe2O4). Sintesis nanofluida menggunakan metode two-step, sedangkan surfaktan yang digunakan adalah oleic acid (OA), polyethlene glycol 400 (PEG 400), tetrabutylammonium bromide (TBAB), gum arabic (GA), dan citric acid (CA). Untuk masing-masing jenis surfaktan dilakukan variasi konsentrasi yaitu perbandingan antara jumlah dopan dan surfaktan. Stabilitas suspensi didasarkan secara kualitatif dengan pengamatan visual terhadap efek separasi dan sedimentasi, dan secara kuantitatif dengan pengukuran Zeta potensial. Hasil terbaik diperoleh untuk surfaktan citric acid dengan perbandingan dopan dan surfaktan adalah 1:0,25 dengan nilai Zeta potensial -35,0 mV, yaitu dalam rentang nilai yang sesuai dengan stabilitas nanofluid yang dihasilkan. Konduktivitas termal nanofluida NiFe2O4 yaitu 0.585 ± 0.007 W/m·K
Sifat Fotoluminisensi Nanokomposit ZnO/GQD (Grafen Quantum Dot)
No full textThe synthesis of ZnO/GQD nanocomposites aims to increase ZnO photoluminescence by conjugating techniques with other luminescent materials, namely graphene quantum dot (GQD). This material is applied as a bioimaging material. ZnO nanoparticles were conjugated with variations of GQD, namely (0.001 g, 0.0015 g, 0.002 g) by hydrothermal method. The results of characterization of ZnO/GQD nanocomposites using XRD show the formation of a hexagonal wurzite structure of ZnO, there is no change in the crystal structure of ZnO, while GQD has an orthorhombic crystal structure. Photoluminescence shows the highest visible light emission peak of ZnO nanoparticles at a wavelength of 620 nm which produces bright yellow luminescence. ZnO/GQD nanocomposites (0.001 g, 0.0015 g, 0.002 g) produced the highest photoluminescence peaks at wavelengths of 550 nm, 590 nm, and 580 nm, respectively. From the PL results, it can be concluded that there was an increase in the photoluminescence intensity with the addition of a small amount of GQD, namely 0.001 g, and there was a shift in the photoluminescence peak towards short wavelengths. This proves that the photoluminescence characteristics of ZnO can be controlled by conjugation with GQDs. Nanocomposites ZnO/GQD potential to be developed as bioimaging material.Sintesis nanokomposit ZnO/GQD dilakukan dengan tujuan untuk mengembangkan sifat optik ZnO dengan mengkonjugasikan material luminisensi yaitu GQD yang diaplikasikan sebagai material kontras pada proses Bioimaging. Nanopartikel ZnO terkonjugasi dengan variasi persentase GQD yaitu 1%, 0,75%, 0,5%. Metode yang digunakan dalam penelitian ini adalah metode hidrotermal. Nanokomposit akan dikarakterisasi dengan 5 alat berbeda. Hasil karakterisasi XRD menunjukkan bahwa pembentukan struktur heksagonal pada ZnO murni, sedangkan ZnO/GQD (0,001 dan 0,0015) merupakan struktur ortorombik, untuk ZnO/GQD 0,002 berbentuk tetragonal. Ukuran kristal ZnO dan ZnO/GQD (0,001, 0,0015, 0,002) masing-masing adalah 58,14 nm, 58,14, 51,22 nm, dan 46,21. Karakterisasi fotoluminesensi menunjukkan puncak emisi cahaya tampak tertinggi nanopartikel ZnO pada panjang gelombang 550 nm yang menghasilkan luminansi kuning cerah. Variasi nanokomposit ZnO/GQD diperoleh rentang panjang gelombang masing-masing 550 nm, 585 nm, dan 570 nm. Rata-rata ukuran partikel yang diperoleh melalui karakterisasi TEM adalah 70 nm. Penambahan GQD dapat mengubah fotoluminesensi nanokomposit ZnO/GQD. Peningkatan intensitas pendaran juga mempengaruhi pengembangan nanokomposit ZnO/GQD sebagai bahan bioimaging
Developing Surface Rainfall Data Based on Blending of Satellite-Based Products and Rain Gauge Observations in the Ngawi Region, East Java
Full text linkRainfall estimation can be performed using various methods, including direct satellite observations (RR-Satellite). However, these estimates show discrepancies when compared to actual observations in-situ rain gauges (RR-Obs). To address this challenge, one potential solution is integrating RR-Satellite with RR-Obs. The Kriging with External Drift (KED) interpolation method is a blending technique that incorporates RR-Satellite as external drift. This study utilized four satellite dataset, namely CHIRP, CMORPH, GSMAP_V8, and IMERG as auxiliary information to generate monthly rainfall estimates (RR-Blended) at 26 rain gauges in Ngawi, East Java, for the period 2001 - 2023. The performance of each satellite dataset was evaluated using Leave-One-Out Cross Validation (LOOCV). The results indicated that RR-Blended using CHIRP (bCHIRP) demonstrated the best accuracy at the climatological scale, with KGE > 0.3 and TSS > 0.65, outperforming other satellite dataset. At the monthly scale, bCHIRP, bCMORPH, and bIMERG showed better performance in different months throughout the year. In terms of spatial accuracy, bCMORPH achieved the highest performance. Our findings suggest that each satellite offers unique advantages based on the time and location of observation. Therefore, we recommend using a weighted combination of RR-Blended from four satellites as the most effective approach for obtaining the best rainfall estimates
Freeze-Thawed PVA Hydrogel Loaded by Morinda Citrifolia L. Leaves Extract with Physical and In-Vitro Antibacterial Properties
Full text linkMorinda citrifolia L. leaves extract (MCLE) has been used as a medical material because of its antibacterial properties. Hydrogels synthesized from polyvinyl alcohol (PVA) are known to be applicable as delivery media for antibacterial substances. This article reports using the freeze-thaw method to use PVA hydrogel as an encapsulation medium for MCLE. PVA/MCLE hydrogel was synthesized in several combinations, namely 10:0, 10:1, 10:2, 10:3, 10:4, and 10:5. The test results showed the conductivity and pH values of the precursor solution increased as the extract fraction increased, but decreased in the viscosity. The hydrogel showed a morphology with increased pore size when the extract fraction in the hydrogel increased. FTIR characterization confirmed that the extract had been successfully loaded into the hydrogel. The swelling degree test of the hydrogels showed an increase for samples 10:1 to 10:3 and a decrease for samples 10:4 to 10:5. Increasing the extract fraction then resulted in a decrease in the gel fraction of the hydrogel. The antibacterial activity test confirmed that the antibacterial activity in the extract remained present after being encapsulated in the hydrogel. Thus, the addition of MCLE affects the performance of the hydrogels to be applied in the medical field
Analysis of Earthquake Risk Estimation for Sustainable Development Using Microtremor Data Based on Vs30 Distribution: Comparative Study of DFA and Geopsy in Central Bengkulu, Indonesia
Full text linkThis research was conducted in Pondok Kelapa Subdistrict, Central Bengkulu Regency, to analyze subsurface characteristics using microtremor data and the Horizontal-to-Vertical Spectral Ratio (HVSR) method. The research compared DFA (Diffuse Field Assumption) and Geopsy approach. In this study, 40 points were measured with a distance between points ranging from 200 to 300 meters. The data were processed using Terraware-HV and Geopsy software with a Monte Carlo approach to model the 3D subsurface structure. Results show that the dominant frequencies range from 0.64 to 8.19 Hz, with high amplification zones between 1.92 and 7.72 concentrated in areas of loose soil, indicating their high seismic susceptibility. Vs30 values range from 55 to 465 m/s, reflecting the dominance of soft to medium materials, such as clay, gravel, sand, and soft rock at specific depths. 3D modeling revealed a heterogeneous distribution of subsurface materials, with high amplification zones requiring special mitigation. This study provides important insights for seismic risk zoning, disaster mitigation, and earthquake-resistant structure design, and supports sustainable development planning in earthquake-prone areas. The results are expected to serve as a reference in spatial management based on earthquake risk mitigation
A Visualization of Ultrasonic Beam from a Medical Transducer using a Combination of Background-Oriented Schlieren Imaging with Hilbert Transformation
Full text linkUltrasonics in the medical field require a safe treatment for patients. The uncontrolled intensities of the ultrasonic waves cause ineffective treatment. So far, the hydrophone probe provides a standard for ultrasonic visualization. However, this method has constraints such as being time-consuming, intrusive, and requiring off-axis measurements. In this paper, an optical method called background-oriented schlieren imaging (BOSI) has been developed as an alternative. The BOSI uses a background of fringe patterns captured by a digital camera. The ultrasonic waves in water displace the patterns relative to the reference. A Hilbert Transform (HT) has been used to estimate the displacement of patterns proportional to the phase difference. The developed BOSI reconstructs these phase differences as an ultrasonic visualization. This paper reports that the developed BOSI is capable of visualizing the ultrasonic waves produced by a 1-MHz frequency medical transducer operated in continuous-wave (CW) mode. The visualization shows an undulation of phase difference that corresponds to the change in water density due to ultrasonic exposure. Meanwhile, the amplitude mode is proportional to the ultrasonic intensity profile. Thus, the developed BOSI is promising to be used as a calibration device to ensure safe ultrasonics in the medical field
Sintesis Komposit Karbon Aktif TKKSTiO2 dengan Aktivasi Gelombang Mikro untuk Pemurnian Emisi Gas Buang Kendaraan Bermotor
No full textThe palm oil plantation industry generates waste besides palm oil products, including empty palm bunch (EPB). This research examines the emission reduction capabilities of motor vehicle exhaust gases using a composite of activated carbon from EPB-AC/TiO2. Surface morphology characterization of the composite is conducted using Brunauer-Emmett-Teller (BET) and Scanning Electron Microscope (SEM). EPB-AC exhibits an average reduction effectiveness of HC gas based on particle size (50, 100, 150, 200 mesh) sequentially at 34.49%, 37.43%, 39.98%, and 43.56%. The average effectiveness of EPB-AC in reducing CO gas sequentially is 70.29%, 71.30%, 72.86%, and 74%. For CO2 gas, EPB-AC has an average reduction sequentially at 52.6%, 54.25%, 56.52%, and 58.54%. On the other hand, the EPB-AC/TiO2 composite exhibits an average reduction effectiveness of HC gas based on particle size sequentially at 42.38%, 43.42%, 45.1%, and 46.57%. The average effectiveness of the EPB-AC/TiO2 composite in reducing CO gas sequentially is 71.24%, 73.52%, 75.54%, and 76.9%. For CO2 gas, the EPB-AC/TiO2 composite has an average reduction sequentially at 54.93%, 54.25%, 59.76%, and 63.05%. Therefore, the best reduction results occur at a particle size of 200 mesh.Industri perkebunan kelapa sawit menghasilkan limbah selain produk kelapa sawit, salah satunya adalah limbah tandan kosong kelapa sawit (TKKS). Penelitian ini bertujuan untuk menguji kemampuan pengurangan emisi gas buang kendaraan bermotor menggunakan komposit karbon aktif (KA) dari TKKS-KA/TiO2. Karakterisasi morfologi permukaan komposit dilakukan menggunakan Brunauer-Emmett-Teller (BET) dan Scanning Electron Microscope (SEM). TKKS-KA menunjukkan efektivitas rata-rata dalam mengurangi gas HC berdasarkan ukuran partikel (50, 100, 150, 200 mesh) secara berurutan sebesar 34,49%, 37,43%, 39,98%, dan 43,56%. Efektivitas rata-rata TKKS-KA dalam mengurangi gas CO secara berurutan adalah 70,29%, 71,30%, 72,86%, dan 74%. Untuk gas CO2, TKKS-KA memiliki rata-rata pengurangan secara berurutan sebesar 52,6%, 54,25%, 56,52%, dan 58,54%. Di sisi lain, komposit TKKS-KA/TiO2 menunjukkan efektivitas rata-rata pengurangan gas HC berdasarkan ukuran partikel secara berurutan sebesar 42,38%, 43,42%, 45,1%, dan 46,57%. Efektivitas rata-rata komposit TKKS-KA/TiO2 dalam mengurangi gas CO secara berurutan adalah 71,24%, 73,52%, 75,54%, dan 76,9%. Untuk gas CO2, komposit TKKS-KA/TiO2 memiliki rata-rata pengurangan secara berurutan sebesar 54,93%, 54,25%, 59,76%, dan 63,05%. Oleh karena itu, hasil pengurangan terbaik terjadi pada ukuran partikel 200 mesh