298 research outputs found
The story of the Soni Ventorum Wind Quintet
No full textThesis (D. Mus. Arts)--University of Washington, 2000The Soni Ventorum Wind Quintet has been the wind quintet-in-residence at the University of Washington School of Music since 1968. Officially founded in 1962, when its members were on the faculty of the Conservatory of Music of Puerto Rico, the group has had a long and stable history. Through their concerts, tours, and recordings, the Soni Ventorum Wind Quintet has established an international reputation. Over the years, many distinguished composers have written works especially for the Soni Ventorum, thus expanding the repertoire of the wind quintet.This study traces the history of the Soni Ventorum Wind Quintet mainly through interviews with the quintet members themselves. This history includes antecedent quintets in which members of the Soni Ventorum Wind Quintet participated (namely, a student quintet at the Curtis Institute, The American Wind Ensemble of Vienna, and the U.S. Seventh Army Symphony Wind Quintet). It covers the founding of the Soni Ventorum Wind Quintet in 1962 at the Conservatory of Music in Puerto Rico through their tenure from 1968 through the present as the wind quintet-in-residence at the University of Washington in Seattle. It gives an account of the establishment of the Soni Ventorum's recording career, their approach to sound and ensemble, their many tours, participation in festivals and competitions, and personnel. The study details the Soni Ventorum's collaborations with colleagues at the University of Washington School of Music, especially the many composers who wrote pieces for the group. One chapter covers ensemble pieces that have been written for the members of the Son! Ventorum Wind Quintet, while another presents wind quintet and quartet arrangements that were prepared by the quintet members themselves. The final chapter provides biographies of the members of the Soni Ventorum Wind Quintet.The Introduction to the study is a brief history of wind quintets. The study concludes with detailed appendices cataloguing the Soni Ventorum Wind Quintet's repertoire, concerts, residencies, tours and a complete discography.At the time of this writing, the author is aware of no other work detailing the history of an established wind quintet
Studi Struktur Elektronik Sel Surya a-Si: H Lapisan Jamak Menggunakan Spektroskopi Elipsometri
No full textSilikon amorf terhidrogenasi (a-Si: H) telah menjadi perhatian besar dalam fundamental fisika yang kaya dan sel surya yang berpotensi murah. Di sini, kami mengamati eksiton dan plasmon yang berkorelasi pada kinerja fotovoltaik dalam film a-Si: H dengan berbagai kandungan H pada substrat Indium In Oxide (ITO) yang diendapkan oleh teknik Radio Frequency-Plasma Enhanced Chemical Vapor Deposition (PECVD). Ellipsometry spektroskopi digunakan untuk menyelidiki kerapatan keadaan elektronik dan parameter optoelektronik. Struktur elektronik dan optik yang diamati dianalisis dengan turunan kedua dengan bentuk garis titik kritis analitik. Fungsi dielektrik kompleks menunjukkan kesesuaian yang baik dengan perhitungan mikroskopis untuk pergeseran energi dan transisi antar-pita yang meluas berdasarkan interaksi lubang-elektron. Menariknya, kami mengamati transfer berat spektral pada rentang energi yang luas yang mengungkapkan korelasi elektronik yang menyebabkan perubahan drastis dalam kepadatan pembawa muatan yang menghasilkan rangsangan resonansi dan plasmon yang berkorelasi. Hasil kami menunjukkan peran penting hidrogen dalam menentukan penggabungan eksiton dan plasmon dalam perangkat fotovoltaik film a-Si: H. Selanjutnya, dari konstanta optik dan ketebalan film tipis, reflektansi dan transmitansi masing-masing sampel diperoleh. Sampel p–i–n dan p–i1–i2–n menunjukkan transparansi yang baik di wilayah inframerah, dan transparansi ini menurun di wilayah cahaya tampak dan menunjukkan pola interferensi dengan penurunan tajam dalam transmisi di tepi penyerapan dan kinerja sel surya (kurva I–V) diukur dengan penggunaan simulator matahari dan sinar matahari. Hasil kami menunjukkan bahwa ada peningkatan yang sangat baik dalam efisiensi sel surya a-Si: H p-i1-i2-n sebesar 8,86% dari struktur p-i-n asli sebesar 5,61%
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Hydrogenated amorphous silicon (a-Si: H) has received a great attention for rich
fundamental physics and potentially inexpensive solar cells. Here, we observe tunable new
resonant excitons and correlated plasmons responsible for photovoltaic performance in a-
Si: H films with various H content on Indium Tin Oxide (ITO) substrate deposited by Radio
Frequency-Plasma Enhanced Chemical Vapor Deposition (RF-PECVD) techniques.
Spectroscopic ellipsometry is used to probe the density of electronic states and the
optoelectronic parameters. The observed electronic and optical structures are analyzed by
the second-derivative with analytic critical-point line shapes. Complex dielectric function
shows good agreement with microscopic calculations for the energy shift and the
broadening inter-band transitions based on the electron-hole interaction. Interestingly, we
observe spectral weight transfer over a broad energy range revealing electronic correlation
that causes a drastic change in the charge carrier density yielding resonant excitons and
correlated plasmons. Our result shows the important role of hydrogen in determining the
coupling of excitons and plasmons in a-Si: H film photovoltaic devices. Furthermore, from
the optical constant and thin film thickness, the reflectance and transmittance of each
sample were obtained. The p–i–n and p–i1–i2–n samples show good transparency in the
infrared region, and this transparency decreases in the visible light region and shows an
interference pattern with a sharp decrease in the transmission at the absorption edge and
the performance of solar cells (curve I–V) measured by the use of sun simulator and
sunshine. Our results indicate that there is a very good improvement in the efficiency of
solar cells a-Si: H p–i1–i2–n amounting to 8.86% from the original p–i–n structure of
5.61%
Power Generation system pada Gas Turbine Generator SGT- 800 Pada PT Kilang Pertamina Balikpapan
No full textThis research aims to evaluate the performance and efficiency of the power generation system in meeting the refinery's energy needs. The research method used involves in-depth analysis of operational and technical data from gas turbine generators, as well as factors that influence performance and efficiency. The research results show that this power generation system is able to provide stable and efficient power output in accordance with refinery demand. Operational parameters such as temperature, pressure and gas flow stability have an important role in maintaining optimal performance. Apart from that, regular maintenance and routine monitoring of critical components are also needed to ensure the smooth operation of the power generation system. These findings provide valuable insights for the energy industry regarding the operation and maintenance of gas turbine generator-based power generation systems. Optimizing operational processes and proper maintenance can increase the efficiency and productivity of power generation systems, thereby supporting smooth refinery operations and minimizing potential disruptions to energy supply. In conclusion, this research highlights the importance of effective management of power generation systems to achieve the desired sustainability and energy efficiency goals
Enhancement of the Silicon Nanocrystals’ Electronic Structure within a Silicon Carbide Matrix
Full text linkUsing plasma-enhanced chemical vapor deposition (PECVD), a mixed gas of silane (SiH4) and methane (CH4) was diluted with hydrogen (H2) to produce thin films of silicon nanocrystals embedded in a silicon carbide (SiC) matrix. This method prevents the co-deposition of SiH and SiC from high-temperature annealing procedures. This study experimentally explores the improvement of the electronic structure by adjusting two processing parameters according to classical nucleation theory (ratio of SiH4 to CH4 and working gas pressure). The deposited films were examined using ellipsometry spectroscopy, X-ray diffraction, scanning electron microscopy, atomic force microscopy, and photoluminescence to determine grain size, crystal volume fraction, topography, and bond configurations. The results show that increasing the working gas pressure can increase the density of SiC, while increasing the ratio of SiH4 to CH4 can only produce larger grain sizes. This is consistent with how SiC works and grows. Without using a high-temperature annealing procedure, this technique can improve the electrical structure of SiC contained in the SiC matrix formed by PECVD
Karakteristik Sel Surya Polikristal Pada Sistem Sun Simulator Menggunakan Lampu Halogen Bulm
Full text linkIn this study, we report that the current-voltage characteristic curve of solar cells provides information about the efficiency of solar cells to convert sunlight directly into electrical energy. The influence of temperature, level of irradiation, as well as the basic materials that are made of it will cause the characteristic curve to change. The halogen lamp is utilized as a light source and is focused in a box with all of its sides being dark as part of a sun simulator that serves as a substitute for the sun's role in the solar system. The solar cell's characteristics are determined by adjusting the irradiation distance and intensity that it receives. The conformity of the output results from measuring the solar cell characteristics in the form of Isc, Voc, Pmax, Imax, and Vmax with the factory specification product obtained. From the results obtained a Voc of 8.59 Volts, an Isc of 0.00539 Amperes, and a Pmax of 0.0217008 Watt at a light intensity of 24.6 Watt/m2.Pada eksperimen yang kami melaporkan, memberikan informasi tentang seberapa efektif sel surya polikristal mengubah sinar matahari menjadi energi listrik dapat ditemukan dalam karakteristik tegangan arus perangkat menggunakan sun simulator. Sun simulator yang kami rancang berdimensi (16x16x35) cm3 menggunakan lampu halogen sebagai pengganti spektrum matahari. Metode eksperimen dari pengukuran kurva karakteristik sel surya polikristal terjadi perubah karena pengaruh suhu, intensitas pancaran, dan substrat. Karakterisasi sel surya dilakukan dengan mengubah jarak radiasi dan jumlah radiasi yang masuk ke sel surya. Hasil yang diperoleh ditentukan dengan mengukur sifat-sifat sel surya dalam bentuk Isc, Voc, Pmax, Imax dan Vmax dengan produk yang ditentukan pabrik. Dari hasil yang didapatkan Voc sebesar 8.59 Volt, Isc sebesar 0.00539 Ampere dan Pmax sebesar 0.0217008-Watt pada Intensitas cahaya 24.6 Watt/m2. Hasil ini mengindikasikan bahwa penggunaan lampu halogen dalam mengganti spektrum cahaya matahari konsisten dengan karakterisasi yang didapatkan
Fabrikasi Sel Surya Berbasis A-Si:H Lapisan Intrinsik Ganda (P-Ix-Iy-N) Dengan Pecvd Dan Analisis Efisiensinya
No full textTujuan utama pada penelitian ini adalah memfabrikasi sel surya lapisan intrinsik ganda (P-ix-iy-N) a-Si:H dengan menggunakan PECVD. Sel surya lapisan intrinsik ganda (P-ix-iy-N) a-Si:H ditumbuhkan di atas substrat glass Indium Tin Oxide (ITO). Untuk mendapatkan lapisan intrinsik ganda dilakukan dengan pengenceran plasma silan oleh hidrogen, dengan rasio perbandingan hidrogen dan silan, R=H2/SiH4 bervariasi, sementara untuk lapisan ekstrinsik tipe-n dan tipe-n dibuat tetap untuk masing-masing sampel. Kemudian pada sampel dilapisan logam pada bagian belakang yang berperan sebagai kontak listrik dan reflector cahaya. Selanjutnya pada masing-masing sampel dikarakterisasi atau dicari sifat fisik yaitu morfologi ketebalan, sifat optik yaitu bandgap, sifat listik yaitu konduktivitas listrik dan karakterisasi I-V sel surya lapisan intrinsik ganda (P-ix-iy-N) a-Si:H dengan sun simulator dan cahaya matahari. Dari pengukuran konduktivitas listrik dari masing-masing sampel terlihat bahwa, fotorespon (ph/pd) lapisan ekstrinsik yang merupakan rasio konduktivitas terang terhadap konduktivitas gelap menunjukkan nilai yang tidak lebih dari 101, sedangkan fotorespon (ph/pd) lapisan instrinsik dapat mencapai 105. Berdasarkan karakterisasi I-V sel surya lapisan intrinsik ganda (P-ix-iy-N) a-Si:H yang diperoleh dalam penelitian ini, mendapatkan efisiensi konversi yang cukup baik (8,86%).
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The main purpose of this research is to fabricate double intrinsic layer (P-ix-iy-N) a-Si:H solar cells by using PECVD. The double intrinsic (P-ix-iy-N) a-Si:H layer was grown on the glass substrates of indium tin oxide (ITO). To produce the double intrinsic layers were achieved by employing a plasma of silane diluted with hydrogen, having various ratio of R=H2/SiH4. Meanwhile, the extrinsic layer of n-type and p-type were made constant for each sample. Sample were then characterized covering properties of, surface morphology, thickness, bandgap, electrical conductivity and I-V curves (photovoltaic performance) by using a sun simulator and sunlight. It was obtained that the photo-response (ph/pd) of the extrinsic layer is around 10, while that of instrinsic one can reach about 105. Further, based on the I-V measurement, the highest efficiency of the (P-ix-iy-N) a-Si:H solar cells is 8.86%
Optimasi MPPT pada Sistem Turbin Angin Nonlinear Menggunakan Firefly Algorithm
Full text linkPenelitian ini membahas pendekatan optimasi Maximum Power Point Tracking (MPPT) pada sistem turbin angin nonlinier menggunakan Firefly Algorithm (FA). Karakteristik nonlinier turbin angin, yang disebabkan oleh fluktuasi kecepatan angin serta interaksi mekanik dan elektrik, menjadi tantangan utama dalam proses ekstraksi daya maksimum. Metode MPPT konvensional sering mengalami keterbatasan dalam hal kecepatan konvergensi dan akurasi pelacakan pada kondisi angin yang dinamis. Oleh karena itu, penelitian ini mengusulkan penggunaan algoritma FA, yaitu algoritma optimasi metaheuristik yang terinspirasi dari perilaku cahaya kunang-kunang, untuk meningkatkan performa MPPT. Sistem konversi energi angin dimodelkan secara matematis dengan mempertimbangkan sifat nonlinier, dan FA digunakan untuk menyesuaikan duty cycle konverter guna mencapai titik daya maksimum secara efisien. Hasil simulasi pada lingkungan MATLAB/Simulink menunjukkan bahwa metode MPPT berbasis FA mampu meningkatkan akurasi pelacakan dan waktu respon dibandingkan dengan metode tradisional seperti Perturb and Observe (P&O) dan Incremental Conductance (IncCond). Metode yang diusulkan juga menunjukkan ketahanan terhadap perubahan kondisi angin dan dinamika sistem. Hasil penelitian ini menunjukkan bahwa Firefly Algorithm merupakan solusi yang menjanjikan untuk optimalisasi sistem energi angin nonlinier dan mendukung efisiensi teknologi energi terbarukan.
Kata kunci: MPPT, Turbin Angin Nonlinear, Firefly Algorithm, Optimasi, Energi Terbarukan
Firefly-Based MPPT System Design for Wind Energy Efficiency Enhancement in Remote Areas
Full text linkThe increasing demand for renewable energy in remote and off-grid areas has highlighted the importance of efficient wind energy utilization. However, wind energy systems are often challenged by unpredictable wind speeds, leading to suboptimal energy harvesting. This study proposes the design of a Firefly Algorithm (FA)-based Maximum Power Point Tracking (MPPT) system to enhance wind energy conversion efficiency. The objective is to develop an intelligent control strategy that optimizes the output power of a wind turbine under fluctuating wind conditions. The proposed system is implemented using a permanent magnet synchronous generator (PMSG) and a DC-DC boost converter. The Firefly Algorithm is employed to dynamically adjust the duty cycle of the converter, thereby maintaining operation at the maximum power point. Simulation results using MATLAB/Simulink demonstrate that the FA-based MPPT outperforms conventional Perturb and Observe (P&O) methods in terms of tracking speed, power stability, and efficiency. The proposed approach achieves faster convergence, reduced oscillations, and higher power output, making it highly suitable for deployment in remote areas with limited access to the power grid. These findings indicate that the integration of intelligent algorithms such as FA in MPPT systems can significantly enhance the performance of wind energy systems in challenging environmentsThe increasing demand for renewable energy in remote and off-grid areas has highlighted the importance of efficient wind energy utilization. However, wind energy systems are often challenged by unpredictable wind speeds, leading to suboptimal energy harvesting. This study proposes the design of a Firefly Algorithm (FA)-based Maximum Power Point Tracking (MPPT) system to enhance wind energy conversion efficiency. The objective is to develop an intelligent control strategy that optimizes the output power of a wind turbine under fluctuating wind conditions. The proposed system is implemented using a permanent magnet synchronous generator (PMSG) and a DC-DC boost converter. The Firefly Algorithm is employed to dynamically adjust the duty cycle of the converter, thereby maintaining operation at the maximum power point. Simulation results using MATLAB/Simulink demonstrate that the FA-based MPPT outperforms conventional Perturb and Observe (P&O) methods in terms of tracking speed, power stability, and efficiency. The proposed approach achieves faster convergence, reduced oscillations, and higher power output, making it highly suitable for deployment in remote areas with limited access to the power grid. These findings indicate that the integration of intelligent algorithms such as FA in MPPT systems can significantly enhance the performance of wind energy systems in challenging environment
Numerical simulation of layer thickness optimization in perovskite solar cells for enhanced power conversion efficiency
No full textPerovskite solar cells (PSCs) have gained significant attention due to their remarkable power conversion efficiency (PCE) and potential for low-cost, scalable production. Despite this progress, further efficiency enhancement requires systematic optimization of device architecture, particularly the thickness of functional layers. This study presents a numerical simulation using the OGMANANO simulation platform to investigate the influence of layer thickness variation, specifically in the perovskite absorber layer, electron transport layer (ETL), and hole transport layer (HTL), on the performance of planar PSCs. The simulation models a typical n-i-p structured device under standard AM1.5G illumination, evaluating key photovoltaic parameters such as short-circuit current density (Jsc), open-circuit voltage (Voc), fill factor (FF), and overall PCE. Results indicate that the optimal absorber thickness lies in the 500–600 nm range, with a peak efficiency of 22.7% achieved at 550 nm. Furthermore, ETL and HTL show optimal performance at 50 and 60 nm, respectively, minimizing recombination losses and enhancing charge transport. The study concludes that precise layer thickness control is critical for maximizing PSC efficiency. The use of OGMANANO proved effective in simulating multilayer perovskite structures, providing a reliable tool for pre-fabrication optimization in advanced solar cell design.
Implementation of CNN-Based Computer Vision for Personal Protective Equipment Detection in the Oil and Gas Industry
Full text linkDue to the inherently hazardous nature of operations in the oil and gas industry, strict compliance with safety protocols, including the obligatory use of Personal Protective Equipment (PPE), is essential for all workers. Nonetheless, monitoring PPE compliance through manual observation remains inefficient and prone to error, especially in expansive, intricate work settings. To address this challenge, there is a growing demand for an intelligent system capable of accurately and instantaneously detecting PPE use. This research introduces a Computer Vision approach employing Convolutional Neural Networks (CNNs) to identify PPE usage among workers within oil and gas environments. The system leverages a comprehensive dataset of images of workers wearing various types of PPE, including helmets, safety vests, and face masks. These images are used to train a CNN model designed to distinguish and classify the safety equipment. Experimental results demonstrate that the proposed CNN model achieves an impressive 94.2% detection accuracy on the validation data and maintains reliable performance across varying lighting conditions and camera angles. Moreover, the system can identify PPE violations in under 1 second per frame, making it suitable for real-time surveillance applications. As a result, this solution offers a promising enhancement to workplace safety oversight, with the potential to markedly reduce accident rates in the industry. The findings also pave the way for future integration with IoT-based monitoring platforms and further refinement of model adaptability across diverse industrial scenarios. The primary innovation of this study lies in the optimized deployment of CNNs tailored to the challenging conditions of oil and gas sites, delivering high detection precision and rapid response times. This area has seen limited exploration in existing literature
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