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Percampuran Vertikal Turbulen di Perairan Halmahera pada Bulan Oktober 2017
Full text linkPerairan Halmahera merupakan pintu masuk utama jalur timur Arus Lintas Indonesia (Arlindo) yang membawa massa air Samudera Pasifik Selatan ke perairan Indonesia. Penelitian ini bertujuan untuk menguantifikasi nilai laju disipasi energi kinetik turbulen dan difusivitas eddy vertikal berdasarkan data suhu dan salinitas yang diakuisisi dengan peralatan CTD (Conductivity, Temperature, Depth). Variabilitas spasial percampuran vertikal massa air di Perairan Halmahera pada bulan Oktober 2017 disajikan berdasarkan data hasil Ekspedisi Widya Nusantara 2017 dengan armada Kapal Riset Baruna Jaya VIII. Metode yang digunakan pada penelitian ini adalah Metode Thorpe Teroptimasi, yang didasarkan pada identifikasi ketidakstabilan profil densitas di kolom air dari CTD. Analisis turbulensi dilakukan dengan menguantifikasi nilai laju disipasi energi kinetik turbulen dan nilai difusivitas eddy vertikal. Dua zona percampuran dengan tingkat turbulen yang kuat ditemukan di Selat Halmahera bagian utara dan di Selat Halmahera bagian selatan hingga Selat Obi. Diperoleh, nilai laju disipasi energi kinetik turbulen pada lapisan termoklin yang membawa massa air Subtropis Pasifik Selatan (SPSW) memiliki orde maksimum 10-7 W/kg di Selat Halmahera bagian utara, 10-8 W/Kg di perairan internal Laut Halmahera dan di Selat Halmahera bagian selatan hingga Selat Obi; dan nilai difusivitas eddy vertikal memiliki orde 10-3 m2/s di Selat Halmahera bagian utara, 10-4 m2/s di perairan internal Laut Halmahera dan di Selat Halmahera bagian selatan hingga Selat Obi
Approximate Analytical Solution of the Ground State Problem of He and He-like Ions using Symmetrized-Hydrogenic States
Full text linkThe matrix method using three symmetrized-hydrogenic basis states has been applied to analytically obtain an approximate solution to the Schrödinger equation of the Helium atom and some He-like ions (2 state made the largest contribution to the ground state energies of the systems, i.e. about 90.9% for He and around 99.9% for Ne8+, and consequently the smallest contribution came from the other two symmetrized states (less than 1%). To conclude, the calculated ground state energies were more accurate than some other simple calculations reported in the literature
Solusi Persamaan Medan Einstein untuk Lubang Hitam Statis dan Bermuatan dengan Potensial Riesz
Full text linkLubang hitam adalah objek astronomi dengan perilaku yang menarik untuk dikaji karena efek gravitasinya yang sangat kuat sehingga cahaya tidak bisa lepas dari efek tersebut. Perilaku lubang hitam dapat ditinjau dari parameter seperti massa, muatan listrik total, dan momentum sudutnya. Artikel ini bertujuan untuk menyelesaikan persamaan medan Einstein dengan menyertakan parameter massa dan muatan listrik total dengan potensial Riesz yang merepresentasikan sebuah lubang hitam. Perhitungan dimulai dengan penentuan inversi dari metrik ansatz, simbol Christoffel, tensor dan skalar Ricci, tensor Einstein, tensor kuat medan elektromagnetik, tensor energi-momentum, dan penyelesaian persamaan medan Einstein. Hasil yang diperoleh berupa solusi persamaan medan Einstein bentuk baru yang mengandung parameter s dengan interval dari 0 sampai tak hingga. Untuk nilai s sama dengan 0, solusi persamaan medan Einstein akan tereduksi menjadi solusi lubang hitam Reissner-Nordström, sedangkan untuk nilai s menuju tak hingga, solusi persamaan medan Einstein akan tereduksi menjadi solusi lubang hitam Schwarzschild. Hasil ini menunjukkan bahwa solusi persamaan Einstein yang diperoleh merupakan generalisasi dari bentuk solusi untuk lubang hitam Reissner-Nordström dan Schwarzschild. Adanya parameter juga dapat menunjukkan evolusi kurvatur ruang-waktu dari metrik Reissner-Nordström ke metrik Schwarzschild
Investigasi Pengaruh Anion Halida terhadap Struktur Kristal dan Sifat Elektronik CsPbX3 (X = F, Cl, Br, I) dengan Metode Density Functional Theory untuk Aplikasi Sel Surya
Full text linkStruktur kristal dan sifat elektronik material perovskite halida CsPbX3 (X = F, Cl, Br, I) telah dipelajari untuk menginvestigasi potensi perovskite CsPbX3 (X = F, Cl, Br, I) untuk aplikasi sel surya. Perhitungan dilakukan menggunakan paket perangkat lunak Quantum Espresso (QE) dengan metode Density Functional Theory (DFT) menggunakan fungsional exchange-correlation PBE-GGA. Perovskite CsPbX3 (X = F, Cl, Br, I) yang dipelajari berada pada fasa kubik dengan grup ruang Pm3m. Studi struktur kristal menunjukkan nilai konstanta kisi CsPbX3 (X = F, Cl, Br, I) meningkat seiring pertukaran anion halida X dari F, Cl, Br, ke I yang berimplikasi pada peningkatan volume sel satuan dan berpengaruh terhadap celah pita energi. Pembentukan VBM dan CBM merupakan kontribusi dari kation Pb dan anion X yang membentuk struktur oktahedral PbF6, PbCl6, PbBr6, dan PbI6. Pita valensi maksimum didominasi oleh orbital p-anion X (X=F, Cl, Br, I) yang berhibridisasi dengan orbital 6s-Pb. Sementara pita konduksi dibentuk oleh orbital 6p-Pb. Hasil perhitungan sifat elektronik menunjukkan celah pita energi dari CsPbF3, CsPbCl3, CsPbBr3, dan CsPbI3 yaitu 2,99 eV; 2,21 eV; 1,79 eV; dan 1,49 eV, secara berturut-turut. Nilai celah pita energi mengalami penurunan seiring dengan meningkatnya jari-jari anion halida X. Diagram pita energi menunjukkan bahwa CsPbX3 (X = F, Cl, Br, I) merupakan material semikonduktor dengan celah pita energi langsung (direct band gap). Sifat ini mengindikasikan bahwa perovskite CsPbI3 dengan celah pita energi 1,49 eV berpotensi sebagai material penyerap foton untuk aplikasi sel surya yang efisien dibandingkan CsPbF3, CsPbCl3, dan CsPbBr3
Effect of Doping Density and Parasitic Resistances on The Performance of Perovskite Solar Cells-based Graphene Oxide as Hole Transport Layer by SCAPS-1D
Full text linkPerovskite solar cells (PSCs) have demonstrated remarkable improvement and promise to be produced as large-scale, low-cost devices. Several resistive losses, such as the loss current, the trapping, and the recombination of charge carriers, significantly inhibited the performance of PSCs. Typically, the series resistance (RS) and shunt resistance (RSH) of the devices influence these kinds of losses. In this study, we conduct a simulation analysis to investigate the effect of doping density and parasitic resistances (RS and RSH) on the performance of PSCs-based graphene oxide (GO) as a hole transport layer (HTL) using the SCAPS-1D. The doping density variations in HTL demonstrate improved power conversion efficiency (PCE) and fill factor (FF) as the doping density increases. Both RS and RSH significantly affect the PSC performance, as they control the shape and slopes of the current density (J-V) characteristic. The optimization method produced impressive results, including an open-circuit voltage of 0.94 V, a short-circuit current density of 22.51 mA.cm−2, a fill factor of 78.92%, and a power conversion efficiency of 16.75%. This study leads to a basic understanding of the physics of PSC devices. The proposed design provides a systematic analysis method for photovoltaic science and technology
Comparison of Hydrocarbon Volumetric Calculation between Cell-Based Model and Numerical Integration
Full text linkVolume estimation for hydrocarbon reserves is a challenging yet pivotal task in engineering for exploration and production. Advances in technology now enable us to compute volume integration using programming computation. Various approaches using numerical integration, including the trapezoidal, pyramidal, and Simpson's rule, along with cell-based models as comparative methods can be used for the calculation of hydrocarbon volume. In this study, original oil in place (OOIP) is employed to determine reserve oil volume. The OOIP values obtained are 8.55 million m3 through cell-based calculations, 8.63 million m3 via the trapezoidal approach, 8.58 million m3 using the pyramidal method, and 8.57 million m3 with Simpson's 3/8 rule. The relative error ratio percentages between the cell-based model as the reference value and the numerical integration calculations as the measured values are 0.93% for the trapezoidal method, 0.35% for the pyramidal method, and 0.23% for Simpson's 3/8 rule. Simpson's 3/8 rule demonstrates the closest mathematical result to the cell-based model. Within this margin of error, the methodologies have been demonstrated to proficiently compute hydrocarbon reserves from real data through simplified and abbreviated processes
Effect of Heat Leakage on Relativistic Quantum Lenoir Engine Performance with a Massless Boson as Working Substance in the Infinite Potential Box
Full text linkA study on the effect of heat leakage on power output, thermal efficiency, and reversibility rate in a relativistic quantum Lenoir engine has been conducted. Initially, we analogize the quantum working substance of the engine, a massless boson trapped in an infinite potential box with a movable right wall, as an ideal gas confined in a pistoned cylinder. Then, the total work, heat input, and heat output of each engine cycle which consists of isochoric, adiabatic expansion, and isobaric compression are extracted by applying the concept of quantum thermodynamics. Finally, power output, thermal efficiency, and reversibility rate of the engine are calculated for different variations of the heat leakage constant. The results are the relationship between several parameters which are expressed in the graph of thermal efficiency vs. compression ratio, graph of efficiency/normal efficiency vs. compression ratio, power output vs. efficiency, and reversibility rate vs. compression ratio. The conclusion is that an increase in heat leakage has an effect on reducing the efficiency and reversibility rate of the engine but does not affect its power output. This work will provide a new chapter for further research related to the use of the boson particle as a working substance in the quantum heat engine, especially the study of the heat leakage effect on engine performance
Geoelectric Modelling Based on Bessel Functions Integral and Damped Least-Square Inversion for Layered Earth Models
Full text linkApparent resistivity formulations of a geoelectric method for layered Earth have been obtained analytically in the Bessel functions integral. This formulation is obtained through the application of two boundary conditions. First, the current density is zero at the Earth's surface. Second, current density and electric potential are continuous at the boundary between the layers. Geoelectric modelling can be done using several model parameters through this formulation. The modelling results show that apparent resistivity formulations based on Bessel function integrals can simulate apparent resistivity curves for layered earth models. The inversion process uses the apparent resistivity formulation based on Bessel function integrals. In this study, the inversion process uses a dumped Least-squared inversion method. The first step begins by testing the inversion program using synthetic data. After that, the inversion program is used in field data. The inversion results using field data from geoelectric data in Mount Pandan, East Java, show that the program was well done, with a minimal error value of 1.24%
Synthesis of CdS Nanoparticles Using The Brimstone
Full text linkThis paper explains and demonstrates how to synthesize Cadmium Sulphide (CdS) nanoparticles (NPs) using brimstone. The brimstone is obtained from Ijen volcanic crater in East Java Indonesia and used as the source of sulfur gas (S2) instead of Na2S. The brimstone was crushed and dissolved in potassium hydroxide (KOH) solution while heated. Acetic acid (CH3COOH) was added, to release the S2 gas. The liquid-gas method was used to prepare the CdS colloid solution. In this study, the effect of variations in the concentration and volume of CH3COOH, temperature variation, and exposure time on the synthesis of colloidal solutions of CdS NPs will be investigated. The absorption edge of the CdS colloidal solution compared to the bulk material experienced a blue shift. This is the evidence of the formation of NPs in solution. It is confirmed by FTIR which shows a CdS absorption peak at 467 cm-1. The radius of CdS NPs was calculated using the Efros equation to obtain a result of approximately 2 nm. Particle size analyzer (PSA) provides a much larger particle size of 20.8 nm. It is assumed that the NPs were agglomerated. Several treatments given, such as varying the volume of CH3COOH, varying temperature, stirring, and varying synthesis time, did not affect the size of the NPs. The cadmium sulfide produced would be used as photocatalist in water treatment application
Peningkatan Kadar Zirkonium Silikat dalam Pasir Puya, Residu Penambangan Emas dari Kecamatan Monterado Kabupaten Bengkayang Provinsi Kalimantan Barat
Full text linkPasir zirkon memiliki kandungan zirkonium berkisar antara 30-50% berat di beberapa lokasi penambangan emas yang berada di Kalimantan Barat. Analisis XRF memperlihatkan persen berat unsur dalam pasir hitam non magnetik (PHNM) dari pasir zirkon yang berasal dari Kecamatan Monterado, Kabupaten Bengkayang adalah 48,05% Zr; 3,35% Si serta unsur lain seperti 20% Ti, 18,95% Fe dan 1,62% Hf. Peningkatan kadar zirkon dilakukan melalui beberapa tahapan yaitu metode fusi alkali dengan perbandingan massa PHNM terhadap massa NaOH yaitu 10 gram : 5 gram (2:1) pada variasi temperatur 700 °C dan 800 °C selama 2 jam, kemudian tahap pelindian menggunakan HCl 2% diikuti oleh pelindian lanjut dalam HCl 37%. Perbedaan temperatur dalam reaksi fusi alkali menghasilkan perbedaan komposisi Zr, dimana pada temperatur 700 °C adalah 88,45% sedangkan pada temperatur 800 °C adalah 90,11% dengan rasio Zr/Si masing-masing adalah 5,33 dan 4,85. Temperatur reaksi fusi alkali pada 800 °C memperlihatkan komponen Zr lebih tinggi dengan rasio Zr/Si yang mendekati ZrSiO4 yaitu 3,25. Analisis jenis mineral menggunakan XRD padat memperlihatkan keberadaan mineral ZrSiO4 dengan struktur kristal tetragonal, memiliki puncak utama pada 2θ adalah 20,04°-20,10°, 26,94°-26,98°, dan 53,48°-53,49°. Ukuran kristal ZrSiO4 berdasarkan perhitungan menggunakan persamaan Debye Scherrer berada dalam kisaran 120,78 nm (2θ = 20,10°), 122,30 nm (2θ = 26,98°), dan 133,17 nm (2θ = 53,48°). Rendemen perlakuan PHNM dengan rangkaian proses reaksi fusi alkali, reaksi basa dan pelindian menggunakan HCl adalah berkisar 33% dengan kadar zirkon silikat dalam produk akhir meningkat dari 46,2% menjadi 90,11%