Mestro: Jurnal Teknik Mesin dan Elektro

Acoustic Pattern Classification in Female Voice Using K-Nearest Neighbor with MFCC Feature Extraction

2026-06-28T02:27:46+00:00

This study investigates the classification of acoustic patterns in female voice signals using the K-Nearest Neighbors (KNN) algorithm and Mel-Frequency Cepstral Coefficients (MFCCs). Acoustic features derived from speech signals contain important spectral information that can be utilized to distinguish variations in voice characteristics. However, variability in speech signals and overlapping feature distributions present challenges for accurate classification. To address this issue, this study employs a structured approach comprising data preparation, MFCC feature extraction, and KNN classification. Each speech sample is represented as a 58-dimensional MFCC feature vector, and the dataset is split into testing and training subsets using a 20:80 ratio. The KNN model is trained using Euclidean distance and evaluated on precision, accuracy, recall, and F1-score. The results show that the proposed approach reaches an accuracy of 87.75%, indicating that MFCC features effectively capture acoustic characteristics in female voice signals. The confusion matrix analysis reveals that categories with distinct acoustic patterns, such as surprise and calm, achieve higher classification performance, whereas overlapping categories, such as happy and disgust, lead to increased misclassification. These findings demonstrate that KNN can serve as a reliable baseline method for acoustic pattern classification. However, further improvements can be achieved through enhanced feature representation and more advanced classification models.

Piping Stress Analysis of XYZ Platform Using CAESAR II: Compliance Verification with ASME B31.3

2026-06-28T03:23:24+00:00

This paper presents the piping stress analysis of the XYZPlatform as part of the EPCI Contract for Platform Reactivation of the XYZ Project, operated by PT. XYZ. The analysis was conducted using CAESAR II Version 2019 (11.0) for piping system Model 03, covering the pipeline from Pig Receiver (R-002) to Upstream HIPPS (Z-010). The objective was to verify compliance with ASME B31.3 (2020) Process Piping code under various load cases including hydrotest, sustained, operating, occasional, and expansion conditions. Line properties analyzed involve 8-inch and 10-inch carbon steel pipes (A106 Grade B and API 5L X52) with design pressure up to 1,550 psi and design temperature of 200°F. Results demonstrate that all maximum stresses are within allowable limits, with sustained stress ratio reaching 60.8%, occasional stress ratio at 61.2%, and thermal expansion ratio at 23.0%. Maximum displacement in the operating condition is 9.013 mm in the X-axis direction, well within the 100 mm threshold. Flange leakage verification using the Pressure Equivalent Method yields a maximum ratio of 77.72%, confirming integrity. The minimum natural frequency of the piping system is 4.585 Hz, exceeding the required 4 Hz minimum. All equipment nozzle loads at the Pig Receiver are within allowable limits per CPY-SPE-0009. The study confirms that the proposed piping configuration for XYZPlatform is structurally sound and compliant with applicable codes and project specifications.

Keywords: ASME B31.3; CAESAR II; XYZPlatform; XYZ Platform; Offshore Piping; Piping Stress Analysis

The Pengaruh Variasi Sudut Kemiringan Pisau terhadap Kapasitas Produksi dan Efisiensi Pemotongan Mesin Pencacah Rumput

2026-06-30T07:33:40+00:00

Forage is the main component in ruminant farming, but manually chopping grass is considered inefficient
in terms of time and effort. This study aims to design and build a grass chopper machine with blade angle
variations of 15°, 30°, and 60°, as well as to find out the effect of each angle on production capacity, the
quality of the chopped grass, and cutting efficiency. The machine is designed using a Honda GX160
gasoline engine with 5.5 hp, an 8:1 ratio pulley transmission system, a frame made of angle iron, and HSS
steel blades, with machine dimensions of 80 cm long, 45 cm wide, and 101.11 cm high. Testing was carried
out by inserting 3 kg of grass material for each blade angle variation. The test results showed that a 60°
blade angle couldn’t be used because it collided with the machine body. A 15° blade angle gave a
production capacity of 72 kg/hour with a cutting efficiency of 63% and uneven chopping quality.
Meanwhile, a 30° blade angle provided the best performance, with the highest production capacity of 90
kg/hour, cutting efficiency reaching 66%, and even chopped quality. Based on these results, it was
concluded that a 30° blade tilt is the most optimal angle to use on a grass chopper machine for producing
good-quality chops more efficiently.