Numerical Beamforming and Parametric Descriptions of Laguerre-Gaussian Vortex Beams

Vortex beams are beams with a helical wavefront that have found applications in optical or acoustic tweezers to manipulate microscopic particles. Vortex beam imposes torque or force to particles, allowing them to trap the object within the beam's field and induce motion or displacement in a non-contact manner. One type of such beam is a Laguerre-Gaussian beam, where the solution of a Gaussian wave equation is modified by the Laguerre polynomial term that determines the pattern and helical characteristic of the beam. In this paper, a numerical method based on the mathematical expression of the Laguerre-Gaussian beam is implemented to describe how the parameters change the physical behavior of the beam. This work has shown that a straightforward numerical method is capable of producing this kind of beam. Therefore, this approach can be used for generating vortex beams for physical emissions, complex numerical simulations, or demonstrations for teaching purposes

Penjadwalan Perkuliahan Dengan Metode Vertex Graph Coloring Dan Simulated Annealing

In college, lecture scheduling is very important in lecturing process, because the activities of lecturers and students depend on lecture schedule. To solve the problem, use Vertex GraphColoring and Simulated Annealing. In Vertex Graph Coloring, look for neighboring and neighboring vertices. While on Simulated Annealing, look for space and exchange positions randomly. The merger of Vertex Graph Coloring and Simulated Annealing aims to create optimum lecture schedule by looking at hard constraint and soft constraint. Testing is done at Faculty of Pharmacy University of North Sumatra, by making schedule from manual to computerized, so it is expected to make the schedule optimally and able to avoid hardconstaint and soft constraint

Analysis of Biomass Briquettes Made from Bagasse Using Tapioca Starch Adhesive with Drying Temperature Variations

Dependency on fossil fuels is making their availability increasingly scarce. Renewable energy is considered the best solution to replace fossil fuels, and at present, the primary focus should be on optimizing the utilization of renewable energy sources. As an example, biomass briquettes are being manufactured using bagasse and tapioca flour as adhesive in a 2:3 ratio. This study utilized a compression force of 50 kgf/cm2 and variations in drying temperatures (100°C, 150°C, and 200°C) for 1 hour. The main objective of this research is to compare the quality of bagasse briquettes with the Indonesian National Standard (SNI) No. 01/6235/2000. The test results indicate that the best conditions were achieved at a drying temperature of 200°C, with a moisture content of 4.47%, a calorific value of 5077.32 cal/g, a combustion rate of 0.1386 g/min, and carbon, volatile matter, and ash content percentages of 22.8333%, 26.845%, and 2.8323%, respectively

Pengaruh Komposisi Campuran Minyak Sereh Wangi dan Minyak Cengkeh terhadap Unjuk Kerja Mesin Diesel

The increase in fuel prices makes the use of essential oils as a natural bio-additive in diesel engines much in demand. This is because essential oils are believed to have good content to improve engine performance and reduce fuel consumption. In this research, essential oils used are citronella oil because they contain carboxylic compounds (-COOH) and clove oil which has the advantage to prevent corrosion. The aim is to improve engine performance and reduce fuel consumption can also prevent corrosion. This research was conducted by mixing citronella oil and clove oil with diesel fuel with a percentage of 1%, 0.5%, and 0.1% of the total volume. The diesel engine is operated with a loading variation of 200, 400, 600, 800, 1000, 1200, 1400, 1600, 1800, and 2000 W at a constant engine speed of 1500 rpm. The variables measured and calculated in this experiment are power, torque, Brake Mean Effective Pressure (BMEP), Specific Fuel Consumption (SFC). The results showed that the addition of citronella oil and clove oil to diesel fuel with a percentage of 0.1%, 0.5%, and 1% significantly reduced fuel consumption by 14.6%, 12.9%, and 18.3%, respectively. The maximum fuel reduction from mixed oils is only 0.086 liters/hour at 1000W loads with 1% bio-additives content

Prediksi Lama Studi dan Predikat Kelulusan Mahasiswa Menggunakan Algoritma Supervised Learning

Untuk menjaga kualitas alumni di suatu universitas, perlu dilakukan prediksi mengenai masa studi dan IPK akhir mahasiswa. Prediksi masa studi dan predikat dapat digunakan sebagai dasar pemberian perlakuan agar mahasiswa dapat lulus tepat waktu dengan nilai yang baik. Lebih lanjut, prediksi tersebut juga dapat digunakan sebagai dasar perbaikan pengelolaan universitas. Penelitian ini bertujuan untuk mengembangkan model klasifikasi menggunakan algoritma supervised learning untuk memprediksi masa studi dan predikat IPK mahasiswa ketika lulus kuliah. Data yang digunakan adalah data alumni Universitas Pekalongan tahun 2018 yang terdiri dari 1208 alumni. Pemodelan dilakukan dengan menggunakan metodologi CRISP DM dengan menerapkan 3 model klasifikasi yaitu KNN, Decision Tree, dan Support Vector Machine. Metrik keberhasilan yang digunakan adalah akurasi. Dari hasil pemodelan, diperoleh bahwa model yang terbaik untuk variabel masa studi adalah SVM dengan nilai akurasi 0.70 dan model terbaik untuk variabel predikat adalah KNN dengan nilai akurasi 0.51

CITRONELLA OIL AS BIOADDITIVES ON SI ENGINE PERFORMANCE CHARACTERISTICS

Current dynamics of world energy supply have driven various innovations by the industry as well as research communities. Fossil fuels, although experiencing a declining interest due to sustainability issues, remain undeniably crucial since they are nearly irreplaceable in some sectors including electricity generation, it is necessary to continuously establish efforts to improve efficiency of those kinds of fuel. In this work, the authors evaluate the potential of locally sourced essential oils, namely citronella, as a fuel additive in a vision of raising the fuel economy of gasoline RON 90. Citronella oil was selected based on a positive hypothesis deduced from its chemical properties, as mentioned in multiple published works. Tests were made on a generator-set powered by gasoline engine using the mixture of RON 90 and citronella oil of various concentrations as the fuels. In addition, a commercial synthetic additive was also tested alongside the essential oil to provide a comparative figure. Meanwhile other investigators suggest a favorable effect of essential oils, our results show that citronella oil additions lead to higher fuel consumption at the same power level. A similar negative effect was also demonstrated by the synthetic additive. The only sector showing positive results is in terms of exhaust temperature where experiments with citronella additives create lower exhaust temperature as compared to pure gasoline and synthetic additives. However, rooms for innovation remain open by exploring other variables such as higher additive concentrations or combining different kinds of essential oils

Aplikasi Penggunaan Serah Wangi Sebagai Bioaditif Alami untuk Karakterasi Unjuk Kerja dari Mesin Diesel

The consumption of diesel fuel in Indonesia is increasing every year, one way to overcome this problem is to use natural bioaditive in the form of essential oils found in Indonesia. Essential oils used in this study are fragrant lemongrass because fragrant lemongrass contains carboxylic compounds (-COOH) [1,2,3]. With the aim of improving engine performance and reducing fuel consumption. This research was conducted by mixing fragrant citronella oil with diesel oil with a percentage of 1%, 0.5% and 0.1% of the total volume. Diesel engines are operated with variations in loading 200, 400, 600, 800, 1000, 1200, 1400, 1600, 1800 and 2000 W at a constant engine speed of 1500 rpm. The variables measured and calculated in this experiment are power, torque, Break Mean Effective Pressure (BMEP), Specific Fuel Consumption (SFC). The results showed that adding citronella oil to diesel fuel with a percentage of 1%, 0.5% and 0.1% significantly reduced fuel consumption by 15.5%, 3.6% and 2.6% respectively. The maximum reduction in fuel consumption reaches 0.055 liters / hour at 200W loading with a bioaditive level of 0.1%. The next study planned is to mix clove oil and citronella oil as bioaditive so that it is expected to reduce fuel consumption and engine corrosion. Keywords: Diesel engine, bioaditive, fragrant citronella oil, performance of diesel engines, fuel consumptio

Tribological analysis on machining performance of Ti-Based coated WC-Co cutting tools

Dissertação de Mestrado em Engenharia de Materiais apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbr

Mechanical Defects Detection on Solar Panel with Ultrasonic Guided Waves

In order to ensure a solar power system runs at its optimum efficiency throughout the lifecycle, proper structuralhealth monitoring on photovoltaic module (PVM) should be performed as part predictive maintenance activities.Mechanical defects such as cracks may induce power loss, raise the risks of electrical failure, and compromise thePVM’s structural integrity. Therefore, early detection of their existence is crucial. This research emphasizes theutilization of ultrasonic guided waves (UGW) to develop an efficient inspection technique. Since the waves cantravel over large distances, they allow long-range defect detection, hence faster inspection process as compared to the conventional bulk wave scan. In this work, UGW experiments were done over areas with cracks of differentseverity. Dispersion characteristics of the propagating modes were evaluated through experiments and numerical simulations, where the obtained results were in agreement to each other. Time frequency analysis shows that certain modes have lower phase velocity in the area with cracks. In addition, the results demonstrate the capability of UGW to detect a crack that is invisible under visual inspection

Mechanical Defects Detection on Solar Panel with Ultrasonic Guided Waves

In order to ensure a solar power system runs at its optimum efficiency throughout the lifecycle, proper structuralhealth monitoring on photovoltaic module (PVM) should be performed as part predictive maintenance activities.Mechanical defects such as cracks may induce power loss, raise the risks of electrical failure, and compromise thePVM’s structural integrity. Therefore, early detection of their existence is crucial. This research emphasizes theutilization of ultrasonic guided waves (UGW) to develop an efficient inspection technique. Since the waves cantravel over large distances, they allow long-range defect detection, hence faster inspection process as compared to the conventional bulk wave scan. In this work, UGW experiments were done over areas with cracks of differentseverity. Dispersion characteristics of the propagating modes were evaluated through experiments and numerical simulations, where the obtained results were in agreement to each other. Time frequency analysis shows that certain modes have lower phase velocity in the area with cracks. In addition, the results demonstrate the capability of UGW to detect a crack that is invisible under visual inspection