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Dewi, Siska Astari
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Chemistry Computer Science & IT Control & Systems Engineering Engineering Industrial & Manufacturing Engineering Materials Science & Nanotechnology Medicine & Pharmacology Public Health Transportation

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PEMODELAN RESPON SURFACE METHODOLOGY (RSM) UNTUK MEMPREDIKSI pH DAN ARUS LISTRIK LARUTAN SISA PENCELUPAN POLIESTER MENGGUNAKAN ELEKTROKOAGULAN Dewi, Siska Astari; Rahma Kusuma Wardhani, Elfira; Novianti, Keke; Nabilla Putri, Salma; Eka Mulyani, Rr Wiwiek
Texere Vol 23, No 1 (2025): Texere Volume 23 Nomor 1 Tahun 2025
Publisher : Politeknik STTT Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.53298/texere.v23i1.02

Abstract

Treating wastewater from polyester dyeing processes using disperse dyes is essential for environmental conservation. Among various treatment methods, electrocoagulation presents a promising alternative for textile effluent remediation. This study developed predictive models using Response Surface Methodology (RSM) to optimize the electrocoagulation process by examining the effects of process duration (0-30 minutes) and applied voltage (5-9 Volts) on pH and electric current. Results demonstrated that the RSM model achieved excellent predictive accuracy for electric current (R² = 0.9786), while the pH model showed moderate correlation (R² = 0.6013). Statistical validation confirmed model reliability through adjusted R², predicted R², and adequate precision values. The research identified optimal time-voltage parameter ranges for experimental waste treatment applications. Both independent variables significantly influenced the observed responses, with voltage exerting a dominant effect on electric current generation during electrocoagulation. These findings contribute to the development of more efficient treatment processes for textile wastewater and align with previous studies highlighting electrocoagulation's effectiveness in pollutant removal from industrial effluents.
A MATHEMATICAL MODEL OF GPS SATELLITE TIME AND FREQUENCY BASED ON THE SPECIAL THEORY OF RELATIVITY Purnomosari, Endah; Dewi, Siska Astari; Mulyani, Wiwiek Eka; Putra, Valentinus Galih Vidia; Abdullah, Fadil
Jurnal Inkofar Vol 9, No 2 (2025)
Publisher : Politeknik META Industri Cikarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.46846/jurnalinkofar.v9i2.475

Abstract

The Global Positioning System (GPS) relies on highly precise atomic clocks in satellites and ground stations to determine global time and position accurately. Relativistic effects, including gravitational fields and satellite orbital motion, induce frequency shifts in these clocks, necessitating corrections for accurate navigation. This study developed a novel approach to integrate general coordinates into GPS, emphasizing implementation simplicity. We investigated the application of special relativity to calculate time and frequency shifts in GPS satellites. Our analysis estimated a daily relativistic correction of approximately 21.6 microseconds, with a positional imprecision of 6.48 km per day if uncorrected. By employing a general time-space coordinate system, we calculated position-4 and velocity-4 vectors, accounting for special relativistic effects on GPS time and frequency. The proposed method simplifies relativistic corrections while enhancing their conceptual clarity. Results demonstrate improved precision and efficiency in GPS positioning through the integration of general coordinates with a streamlined approach. This research offers valuable insights for international engineering communities, scholars, and practitioners, advancing the understanding of relativity’s impact on GPS satellite operations.
Co-Authors Eka Mulyani, Rr Wiwiek Fadil Abdullah mulyani, wiwiek eka Nabilla Putri, Salma Novianti, Keke Purnomosari, Endah Putra, Valentinus Galih Vidia Rahma Kusuma Wardhani, Elfira