Emisi gas buang merupakan zat/unsur dari pembakaran didalam ruang bakar yang dilepas ke udara yang ditimbulkan oleh kendaraan bermotor, sehingga dapat menimbulkan dampak terhadap lingkungan, terutama dapat menyebabkan polusi udara, lingkungan, dan perubahan iklim global. Untuk mengatasi permasalahan tersebut diperlukan cara lain agar dapat menghemat bakar yang sederhana, bahan relatif murah, dan mudah didapatkan. Salah satu caranya menggunakan ferrite magnet untuk mengurangi emisi gas buang yang dihasilkan. Metode yang digunakan dalam penelitian ini berdasarkan standar SNI 19-7118.3-2005 dengan pengukuran emisi gas buang pada kendaraan berbahan bakar bensin yang dilakukan pada kondisi idle. Namun untuk penelitian dapat juga dilakukan pengujian pada bukaan katup (throttle) yang berubah yang menggunakan metode pengujian kecepatan berubah dengan katup (throttle) terbuka penuh. Dari penelitian ini diperoleh bahwa pemasangan ferrite magnet pada kendaraan four stroke engine 125 cc dapat mempengaruhi emisi gas buang kendaraan yang dihasilkan saat menggunakan bahan bakar pertalite maupun pertamax. Kadar emisi gas buang yang didapat adalah 562 ppm vol (ferrite pertalite) untuk gas HC, 8,53% untuk gas CO (pertalite/pertamax), 10,8% untuk gas CO2 (ferrite pertamax), dan untuk gas O2 kadar emisinya sebesar 14,91% (ferrite pertalite).
Misalignment is a condition where the centerlines of two coupled shafts do not coincide. Misalignment is the commonly fault in rotating machinery. Detection and diagnosis of shaft misalignment is crucial to achieve its optimal performance. The purpose of research is to diagnose shaft misalignment using multiclass support vector machine (SVM). The time-domain vibration signals of a shaft alignment rig with normal, parallel misalignment and angular misalignment of shaft conditions were obtained from vibration measurement signals. The accelerometer was used to measure vibration with a sampling frequency of 20 kHz at the constant speed operation of 1000 rpm. The features of median, RMS, crest factor, variance, kurtosis, shape factor, impulse factor, skewness, range, standard deviation and maximum were extracted from the vibration signal. The Principal Component Analysis (PCA) was applied for reduce the number of variables for data input to principal components with lower dimension. The multiclass SVM with One Against One (OAO) methodand linear kernel were used for classification. The results show that SVM for diagnosis of shaft misalignment show a good performance with an accuracy of 100%.
Rapid prototyping or commonly known as additive manufacturing uses metal and non-metal semi-liquid materials which are compacted layer by layer. Fused deposition modeling (FDM) is one of the methods in the additive manufacturing process that uses thermoplastic filaments (PLA and ABS). Poly Lactic Acid (PLA) or poly lactic acid is an organic plastic or bioplastic made from renewable biomass sources such as corn starch, pea starch and vegetable oils. Important factors affecting the quality of 3D Printing results are nozzle diameter, nozzle temperature, bed temperature, infill patern, infill percentage, print speed, layer thickness and infill overlap. Infill overlap is the percentage of overlapping processes of the filament during the printing process. This research was conducted to determine the effect of infill overlapon the physical and mechanical properties of 3d printing products. The infill overlapvariations used are 0%, 25%, 50%, and 75% of the nozzle diameter. 50% variation shows better quality when compared to other variations for density test, tensile test, and bending test.
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