مجله انجمن مهندسی صوتیات ایران
سال دوازدهم شماره 1 (پیاپی 22، بهار و تابستان 1403)

Mining activities often cause environmental problems, such as noise pollution, which can endanger ecosystems and human health. This research aimed to study the extent of noise pollution resulting from stone quarry activities in a protected area. For this purpose, sampling was carried out in three directions—north, south, and east—up to a distance of 1 km (11 stations in each direction) and in the west up to a distance of 470 m (5 stations) from the Qanbari stone quarry over one year, from October 2022 to September 2023, between 9:00 and 11:00 a.m. Noise levels were measured using a Cirrus sound level meter (model CR:303), with five samples collected from each station, totaling 2,280 samples. A comparison of the mean sound intensity levels in the four directions—north, south, east, and west—against the international standard limit for daily noise set by the WHO for protected areas (45 dB) showed that the mean sound intensity levels in all directions exceeded the standard limit, indicating noise pollution. Correlation analysis results revealed strong negative correlations between distance and noise, as well as between elevation and noise. In other words, as distance and/or elevation above sea level increased, sound levels decreased. Based on the findings of this study, which highlight the positive effect of geological features such as mountains in reducing noise, it is recommended that land barriers in the form of embankments and hills covered with plants capable of high noise absorption be constructed within a one-kilometer radius of the quarry. Additionally, due to the continuous noise pollution caused by mining activities in the heart of the Basiran no-hunting area, it is suggested that mining operations that disturb wildlife quietness be banned by the Department of Environment. This measure could help increase wildlife populations and enhance the potential of the area to be designated as a fourth-level protected area under the supervision of the Department of Environment.

In this article, the production of high-quality thin-layer graphene using the liquid-phase exfoliation method has been investigated. The step probe was designed using COMSOL Multiphysics. The diameter of the reaction vessel and the distance of the probe tip from the bottom of the vessel were studied in relation to graphene production. The diameters of the containers used were 60 mm, 75 mm, and 85 mm, while the distance of the probe tip from the bottom of the container varied from 20 mm to 50 mm. Initially, the effect of acoustic pressure in each container was simulated. The highest acoustic pressure difference obtained in the simulation was 7.74×10⁷ Pa for a container with a 60 mm diameter and a probe-to-bottom distance of 50 mm. The results of ultraviolet-visible spectroscopy of the samples indicated the presence of a higher amount of graphene, with a peak at 266 nm. Using the Beer-Lambert law, the concentration of the produced graphene was estimated to be approximately 0.13 g/L. SEM and TEM analyses confirmed the production of few-layer graphene with good quality. Finally, Raman spectroscopy was used for complementary characterization of the samples. The I₂D/I_G ratio was found to be approximately 1.02, confirming the successful production of few-layer graphene in this study.

Since ancient times, various technologies have been developed to combat agricultural pests. Due to the limitations of each of these technologies, efforts have been made to introduce more efficient methods or to complement existing technologies by addressing their shortcomings through overlapping approaches.In this research, vortex sound generator technology has been introduced as a potential new solution in this field, and its initial efficiency has been experimentally evaluated. The vortex generates variable pressure intensities, resulting in a high-pressure gradient and, consequently, a strong momentary force that causes damage to living organisms.The obtained results suggest that in the near future, this technology could be incorporated into the portfolio of pest control methods, particularly for combating invasive locusts and possibly other similar cases.

A test cell is used to evaluate the performance of aerospace jet engines. In this study, an ejector pump model is employed to analyze the engine output nozzle flow. The interaction between the flow exiting the nozzle and the test cell augmentor is examined. The augmentor flow is calculated using thermodynamic equations, while key design parameters, including the exit temperature of the test cell and the noise generated by the exit jet velocity, are investigated. The results are obtained for an ambient temperature range of -15°C to 75°C. The lowest and highest ambient temperatures result in the maximum flow rate and outlet temperature. In the most critical condition, the exit jet velocity must not exceed 40 m/s, and the jet exit temperature should remain below 300°C. The Computational Fluid Dynamics (CFD) method is used to analyze gas dynamics and acoustics. ANSYS software is utilized for meshing, and Fluent commercial software is applied for the analysis. The maximum sound intensity at a distance of 3 meters from the engine is found to be 175 dB, while the maximum sound intensity outside the test cell is approximately 95 dB. Additionally, the flow velocity at the test cell exit remains below 40 m/s.

Researchers typically expose aquatic animals to sound treatments and conduct behavioral observations to understand the impact of anthropogenic noise on animals in small, water-filled tanks. In this study, using a methodological approach, a model for measuring and analyzing underwater sound levels in a fish tank is presented. Measurements of sound pressure levels were taken under ambient background noise conditions (with and without the use of an underwater loudspeaker), as well as for an increased sound pressure level at three-dimensional locations (length, width, and height) within a fish tank. There was no significant difference (P > 0.05) in sound levels between the two absolute ambient conditions (96.03 and 96.13 dB re 1 µPa for conditions with and without underwater speaker playback, respectively). However, a significant difference (P < 0.001) was observed between ambient sound conditions and the elevated sound playback treatment (96.40 dB re 1 µPa). Due to the complexity of underwater sound fields in laboratory-based experiments, the use of standardized playbacks and the creation of biologically relevant acoustic stimuli are crucial to avoiding pseudoreplication and ensuring the reliability of underwater bioacoustic studies and behavioral research. Furthermore, to produce rigorous, evidence-based science that enhances reproducibility and repeatability in underwater acoustic studies, it is recommended to provide open-source metadata, a detailed methodology, and explicit reporting of acoustic component measurements in behavioral studies.