Faraday: Journal of Fundamental Physics, Research, and Applied Science

The Application of a Finite Impulse Response Low-Pass Filter for Noise Reduction in Voice Signals

Fauziyah Vida Rahmah Wijaya — 2026-02-28

This study investigates the effect of noise on human voice signals and noise reduction efforts using digital signal processing techniques. The objective of this research is to analyze and compare the frequency characteristics and clarity of the original voice signal with those of noise-contaminated signal after undergoing a filtering process in MATLAB. The research methodology includes voice recording, superposition of the voice signal with noise, and filtering using a 50^th-order Finite Impulse Response (FIR) low-pass filter with a cutoff frequency of 500 Hz implemented in MATLAB. The analysis is conducted in the frequency domain using the Fast Fourier Transform (FFT) and in the time domain through waveform observation. The results indicate that noise introduces high-frequency components and irregular amplitude fluctuations. After filtering, the high-frequency components are effectively attenuated, resulting in a smoother and more stable signal while preserving the primary characteristics of the human voice. These findings demonstrate that the FIR low-pass filter is effective in improving the quality of human voice signals.

Seismicity Analysis of Earthquake in Bengkulu Using Gutenberg-Richter and Omori laws

Fiska Tobamba — 2026-02-28

Bengkulu Province is one of the regions in Indonesia with high seismic aktivity because it lies within the Sumatra tectonic plate zone and is crossed by the Sumatra Fault system. This tectonic setting makes Bengkulu highly vulnerable to Earthquake. This study analyzes the seismic characteristics of Bengkulu Using the Gutenberg-Richter law and examines the aftershock pattern following the major earthquake of june 4, 2000, based on the Omori-Utsu law. The data were obtained from the USGS earthquake catalog, consisting of earthquake records from 2015-2025 and afthershock data for 30 days after the mainshock. The Gutenberg-Richter Analysis evaluates the relationship between log10N and moment magnitude (Mw) to determine the a and b values. Meanwhile, Omori-Utsu Analysis examines the relationship between log10 n(t) and log10 (t+c) to obtain the parameters p and k. The result show that Bengkulu's seismicity is dominated by small to moderate earthquakes with relatively low b-values, indicating high tectonic stress conditions. The aftershock Analysis produced a p-value of 1.4822 with an R² value of 0.7767, showing rapid aftershock decay consistent with the Omori-Utsu law. These findings confirm Bengkulu has a high seismic Hazard level, emphasizing the need for continuous mitigation and preparedness efforts.

Comparison of Silver and Aluminum Patches on the Electromagnetic Radiation of a Microstrip Dipole Antenna

Aslam Chitami Priawan Siregar — 2026-02-28

This paper compares silver (Ag) and aluminum (Al) as patch materials for a microstrip dipole antenna to examine how their electrical conductivities affect electromagnetic radiation performance. Both antennas were designed with identical geometrical and substrate parameters using the Finite-Difference Time-Domain (FDTD) method, varying only the patch material. Simulation results show that the resonant frequencies are 2.4700 GHz for Ag and 2.4649 GHz for Al, with excellent VSWR values 1.0839 and 1.0836 and return loss below –27 dB. Both materials exhibit reflected power below 0.2% and have nearly identical radiated power, namely 0.3647 W for silver (Ag) and 0.3646 W for aluminum (Al). Overall, silver and aluminum demonstrate almost identical radiation characteristics. Silver offers slightly better conductivity, while aluminum provides similar efficiency at lower cost, making it a practical alternative for lightweight and economical microstrip antenna applications.

Optical Band Gap of PMMA: Cody, ASF, and DASF Methods Compared to Tauc

Allif Rosyidy Hilmi — 2026-02-28

This study aimed to determine the optical band gap of polymethyl methacrylate (PMMA) using alternative methods to the conventional Tauc plot. PMMA was prepared by solution casting and characterized using UV–Vis spectroscopy. The optical band gap was approximated by applying the Cody, Absorption Spectrum Fitting (ASF), and Derivative ASF (DASF) methods, and the results were compared with those from the Tauc approach. The optical band gap values ranged from 3.10 eV to 4.94 eV, which fall within or near the range reported in the literature for PMMA, depending on the analysis method and transition model used. Each method had distinct advantages: the Cody method provided a clearer linear region for amorphous systems, ASF offered a practical approach that did not require sample-thickness information, and DASF enhanced precision through derivative-based analysis. The observation of band gap values corresponding to both direct and indirect optical transitions suggests the presence of multiple effective optical transition pathways in amorphous PMMA. These findings demonstrate that the Cody, ASF, and DASF methods can serve as reliable alternatives to the Tauc method for analyzing the optical properties of polymeric materials.

Review: Synthesis of rGO in Its Use as Thin Films with Various Polymer Matrices

Rahma Alya Hidayah — 2026-02-28

Reduced graphene oxide (rGO) is a two-dimensional carbon material that has been widely developed as a functional filler in polymer-based thin films due to its high surface area, good electrical conductivity, and adequate interface compatibility. This article presents a literature review on the synthesis of rGO and its use as thin films with various polymer matrices, namely polyaniline (PANi), poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride–trifluoroethylene) [P(VDF-TrFE)], and chitosan. The review was conducted on open access scientific articles discussing rGO synthesis methods, thin film fabrication techniques, and structural, morphological, thermal, and electrical characterization of composite materials. The results of the study show that rGO can improve the functional performance of polymer thin films through the formation of conductive networks, strengthening of interface interactions, and crystal nucleation effects. In the PANi matrix, rGO increases electrical conductivity and stability, while in PVDF and P(VDF-TrFE), rGO promotes the formation of electroactive crystalline phases that enhance piezoelectric properties. Meanwhile, in chitosan, strong interfacial interactions improve electrochemical response and the potential for environmentally friendly sensor applications.

A Comparative Analysis of the Mechanical Properties of Cortical–Trabecular Bone Materials and Calcium Silicate Materials for Bone Tissue Engineering Applications

Sovi Anggraini Armita Dewi — 2026-02-28

Biomechanical modeling of bone plays an important role in bone tissue engineering by enabling the understanding of the mechanical response of natural bone and substitute materials under physiological loading. This study aims to compare the mechanical properties of cortical–trabecular bone materials as an environment for tissue support with calcium silicate (CaSiO₃) as an engineered artificial substitute using the finite element method. A long-bone phantom model in the form of a hollow cylindrical structure was developed by separating cortical and trabecular regions and analyzed using ANSYS Workbench. The applied loading scenarios included lateral bending with a load of 500 N and axial compression with a load of 1000 N. The analyzed mechanical parameters were total deformation and equivalent (von Mises) stress. Simulation results show that cortical–trabecular bone is able to distribute stress more adaptively, with greater deformation occurring in the trabecular region and stress concentration in the cortical layer. Meanwhile, calcium silicate exhibits higher stiffness with smaller deformation but comparable maximum stress values. These findings indicate that the compatibility of mechanical properties between scaffold materials and natural bone significantly affects the effectiveness of bone tissue engineering applications.