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Background and Objective: A practical method for noise control in environments with different noise sources is designing an acoustic cabin for the workers. In this regard, this study aimed to assess the efficiency of the acoustic cabin in a typical turbine unit of a thermal power plant to provide acoustic comfort. Materials and Methods: Measurement of the noise level and spectrum, as well as vibration as exposed to whole body were conducted using sound level meter Brüel & Kjær 2260 Sound Level Meter; Denmark model 2260. The acoustic cabin was designed using sandwich panel structure based on standard ISO 15667. The composition of cabin walls with 104 mm total thickness from outside to inside included 2 mm steel sheet, 40 mm polyurethane foam with a density of 50 kg/m3, 2 mm steel sheet,50 mm rock wool with a density of 120 kg/m3, and 10 mm plaster tile, respectively. It should be noted that the floating floor was implemented for the reduction of transmitted vibration to the cabin. Results: The obtained results indicated that the means of noise levels equivalent to sound pressure were approximately 89.5 and 50.7 dB outside and inside the designed cabin, respectively, resulting in an overall noise reduction of 40 dB. The results demonstrated that an acceleration level of vibration as exposed to the whole body inside the cabin was lower than the comfort vibration limit of 0.145 m/s2. Conclusion: In order to design a high-efficiency acoustic cabin, the selection of material types, thickness, and density is critical to optimize the overall sound transmission of the walls. Therefore, the results confirmed that in designing the acoustic cabinet, sandwich panels with adequate mass, low hardness coefficient, and high damping can provide optimal acoustic conditions.

Background and Objective: A practical method for noise control in environments with different noise sources is designing an acoustic cabin for the workers. In this regard, this study aimed to assess the efficiency of the acoustic cabin in a typical turbine unit of a thermal power plant to provide acoustic comfort. Materials and Methods: Measurement of the noise level and spectrum, as well as vibration as exposed to whole body were conducted using sound level meter Brüel & Kjær 2260 Sound Level Meter; Denmark model 2260. The acoustic cabin was designed using sandwich panel structure based on standard ISO 15667. The composition of cabin walls with 104 mm total thickness from outside to inside included 2 mm steel sheet, 40 mm polyurethane foam with a density of 50 kg/m3, 2 mm steel sheet,50 mm rock wool with a density of 120 kg/m3, and 10 mm plaster tile, respectively. It should be noted that the floating floor was implemented for the reduction of transmitted vibration to the cabin. Results: The obtained results indicated that the means of noise levels equivalent to sound pressure were approximately 89.5 and 50.7 dB outside and inside the designed cabin, respectively, resulting in an overall noise reduction of 40 dB. The results demonstrated that an acceleration level of vibration as exposed to the whole body inside the cabin was lower than the comfort vibration limit of 0.145 m/s2. Conclusion: In order to design a high-efficiency acoustic cabin, the selection of material types, thickness, and density is critical to optimize the overall sound transmission of the walls. Therefore, the results confirmed that in designing the acoustic cabinet, sandwich panels with adequate mass, low hardness coefficient, and high damping can provide optimal acoustic conditions. [ABSTRACT FROM AUTHOR]

Identification of susceptible areas to landslide occurrence is one of the basic measures in reduction of possible risk and hazard management. The main goals of this paper are investigation on designed forest road network according to landslide hazard zonation and comparing applicability of two experimental landslide hazard zonation models (Haeri-Samiei and Mora-Varson) at the Shastkalate forests, Gorgan. By field work, the occurred land slides at the study area were gathered and recorded by GPS device. The elements for each model were generated and prepared in GIS. The landslide zonation for study area was done using mentioned models and their required factors. The efficiency of outputs of models was assessed by DR and QS indices. The results showed that at the study area the Haeri-Samiei model with QS= 1.251 had relative desirability compared to Mora-Varson model (QS= 0.586). In order to investigate on designed road network, the road network map was prepared. Based on results, using Haeri-Samiei model, situation of roads and rate of being at hazards were determined. Results showed that there are many of roads in high risk zones which should be designed again by forest managers.