Article Per Year (5 Year)
p-Index From 2021 - 2026
0.444
P-Index
This Author published in this journals
All Journal Jurnal Presipitasi : Media Komunikasi dan Pengembangan Teknik Lingkungan Journal Of World Science
Marcelinus Christwardana
Universitas Diponegoro
Agriculture, Biological Sciences & Forestry Computer Science & IT Earth & Planetary Sciences Economics, Econometrics & Finance Engineering Health Professions Law, Crime, Criminology & Criminal Justice Social Sciences

Published : 2 Documents Claim Missing Document
Claim Missing Document
Check
Articles

Found 2 Documents
Search

 1 
Experimental Investigation of by-Product Hydrogen Gas in the Harvesting Process of Dunaliella salina using a Non-Sacrificial Cathode Purwono Purwono; Hadiyanto Hadiyanto; Marcelinus Christwardana; Widayat Widayat; Mochamad Arief Budihardjo
Jurnal Presipitasi : Media Komunikasi dan Pengembangan Teknik Lingkungan Vol 21, No 1 (2024): March 2024
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/presipitasi.v21i1.80-89

Abstract

Hydrogen gas is considered a pollution-free fuel in the future. However, the EC process using these non-sacrificial electrodes requires further research especially for the production of dissolved hydrogen gas and the efficiency of microalgae harvesting. The purpose of this study was to investigate the concentration of dissolved hydrogen gas produced from the harvesting process of Dunaliella salina microalgae species using EC and ORP concentrations including pH, harvesting efficiency due to voltage variations and harvesting time using EC with non-sacrificial electrodes. D salina harvesting using EC reactor made of cylindrical borosilicate glass. Spiral-shaped type 304 stainless steel (non-sacrificial) serves as the cathode and solid cylindrically-shaped Fe serves as the anode. The voltage set varies between 16, 18, and 20 Volts, while the electrolysis time is varied between 1.3.5 minutes. The results showed that the highest dissolved hydrogen concentration of 820 ppb (0.820 ppm) produced from the EC process used 18 V for 3 minutes. The volume of gas could not be measured because most of the hydrogen gas was dissolved in the D salina culture, so it was not enough to evaporate within 3 minutes. The maximum ORP concentration of -413 mV resulting from the EC process uses 18 V for 3 minutes. When hydrogen gas is present in a solution, it can decrease the ORP value of the solution. At EC time with non-sacrificial electrodes for 5 minutes managed to harvest D salina 50.79%; 61.90%; 74.60% at voltages of 16 V, 18V, and 20 V respectively. 
Use Of Machine Learning With The Long Short Term Memories Method As The Basis For Cleaning And Performance Of Steam Turbine Condensers For Gas And Steam Power Plants Tony Suryo Utomo; Marcelinus Christwardana; Guntur Syachrir
Journal of World Science Vol. 4 No. 5 (2025): Journal of World Science
Publisher : Riviera Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.58344/jws.v4i5.1411

Abstract

This research focuses on the design of a bidirectional reinforced concrete slab for a 5-storey apartment building located on Jalan Pemuda, Semarang, following SNI 1726:2019 standards. The objective is to compare the results of the direct design method (DDM) using Excel with ETABS v18 software, analyzing the accuracy of traditional methods in modern structural designs. The study employed a practical approach, incorporating various design parameters such as beam dimensions, span length, dead and live loads, and material strengths (f'c and fy). The results indicate that although there is a slight difference between the methods, they exhibit similar trends. The study found that increased load leads to higher moments, while larger beams and higher concrete strength reduce reinforcement requirements. However, discrepancies between the methods were observed due to rounding errors in the DDM. The research suggests refining moment calculation techniques and enhancing software tools for more accurate slab designs. The findings are essential for improving design accuracy in both academic and professional practice, particularly for earthquake-resistant structures.
Co-Authors Guntur Syachrir H Hadiyanto Mochamad Arief Budihardjo Purwono Purwono Tony Suryo Utomo Widayat Widayat