Ebrahim Taban | Mashhad University of Medical Sciences, Mashhad. Iran. (original) (raw)
Papers by Ebrahim Taban
Applied Acoustics
In this study, hybrid composites made of polyurethane (PU) matrix and natural kenaf fiber filler ... more In this study, hybrid composites made of polyurethane (PU) matrix and natural kenaf fiber filler were designed and fabricated. The Response Surface Methodology (RSM) optimization approach coupled with a Central Composite Design (CCD) was used to design the experiments and optimize the parameters affecting the acoustic performance of the samples in the low and mid-frequency ranges. The acoustic performance of the samples was investigated using the impedance tube method. Additionally, the acoustic performance was predicted using a developed Quadratic model as well as the Delany-Bazley (DB) and Johnson-Champoux-Allard (JCA) models. The results showed that the acoustic absorption of neat PU foam is remarkably improved at all frequencies with the addition of kenaf fibers as the filler. It was found that the acoustic performance of the composite samples is optimal when the added amount of kenaf fibers to the polymer matrix and fiber length are 1.2 wt% and 8 mm, respectively. The sound absorption average (SAA) of the optimized composite and neat PU foam was calculated as 0.65 and 0.48, respectively i.e., an increase of 35.4 %. The Quadratic model showed very high accuracy for the prediction of the SAA of the optimized sample. The JCA model provided higher accuracy for the prediction of the frequencydependent sound absorption coefficient of the composites as compared with the DB model.
Journal of Environmental Health Science and Engineering
Journal of Natural Fibers, Feb 20, 2023
International Journal of Environmental Science and Technology
In recent years, rapid economic development and urbanization have led to severe environmental pro... more In recent years, rapid economic development and urbanization have led to severe environmental problems such as noise pollution. The use of fibrous porous materials is considered to be an effective method to control noise pollution. This study investigates the morphological and acoustical characteristics of fibrous materials made of aluminosilicate fibers (ASFs). To this end, morphological and structural properties of samples were investigated using field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) method. The effect of sample thickness and air gap was experimentally studied using the impedance tube method in the frequency range of 63-6300 Hz. The frequency-dependent acoustic behavior of the samples was also predicted using the empirical models of Delany-Bazley (D-B), Garai-Pompoli (G-P), and the proposed revised models of D-B and G-P. The XRD patterns showed that the main phases of the ASF are quartz, tridymite, and mullite. The BET analysis confirmed that the samples are classified as macro-porous. It was found that with the increase of the sample thickness sound absorption coefficient (SAC) increases at low frequencies. The averages of SACs for samples with thicknesses of 10 and 25 mm at low frequencies were 0.17 and 0.32, respectively. These values for the middle frequencies were 0.78 and 0.80, and for high frequencies were 0.83 and 0.84, respectively. Additionally, it was observed that with the increase of air gap depth, SAC enhances at low-frequency bands, and the SAC peak shifts toward the lower frequencies. Additionally, excellent agreement was observed between the experimentally measured SACs and those predicted by the revised D-B and G-P models.
springer, 2022
In recent years, rapid economic development and urbanization have led to severe environmental pro... more In recent years, rapid economic development and urbanization have led to severe environmental problems such as noise pollution. The use of fibrous porous materials is considered to be an effective method to control noise pollution. This study investigates the morphological and acoustical characteristics of fibrous materials made of aluminosilicate fibers (ASFs). To this end, morphological and structural properties of samples were investigated using field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) method. The effect of sample thickness and air gap was experimentally studied using the impedance tube method in the frequency range of 63-6300 Hz. The frequency-dependent acoustic behavior of the samples was also predicted using the empirical models of Delany-Bazley (D-B), Garai-Pompoli (G-P), and the proposed revised models of D-B and G-P. The XRD patterns showed that the main phases of the ASF are quartz, tridymite, and mullite. The BET analysis confirmed that the samples are classified as macro-porous. It was found that with the increase of the sample thickness sound absorption coefficient (SAC) increases at low frequencies. The averages of SACs for samples with thicknesses of 10 and 25 mm at low frequencies were 0.17 and 0.32, respectively. These values for the middle frequencies were 0.78 and 0.80, and for high frequencies were 0.83 and 0.84, respectively. Additionally, it was observed that with the increase of air gap depth, SAC enhances at low-frequency bands, and the SAC peak shifts toward the lower frequencies. Additionally, excellent agreement was observed between the experimentally measured SACs and those predicted by the revised D-B and G-P models.
Building and Environment, 2022
Work, 2022
BACKGROUND: Exposure to traffic noise could play an important part in inducing psychological diso... more BACKGROUND: Exposure to traffic noise could play an important part in inducing psychological disorders which in turn can affect individuals’ cognitive and mental performance. OBJECTIVE: The aim of this study was to determine the effect of traffic noise exposure on the cognitive performance with regard to subjects’ personality traits. METHODS: Sixty students with normal hearing and vision took part in this experimental study. In order to simulate the traffic noise condition of Tehran, the noise from several busy streets was first carefully recorded. Later on, the subjects were exposed to this recorded noise in an anechoic chamber. Also, the NEO-five factor inventory questionnaire and the continuous performance test were used to assess personality traits and cognitive performance of participants respectively. RESULTS: The results showed that the cognitive features of the study, such as reaction time and the number of commission/omission errors in continuous performance testing increas...
Building and Environment, 2022
Building and Environment, 2020
Abstract The use of natural fibers in the buildings and construction industries as a sustainable ... more Abstract The use of natural fibers in the buildings and construction industries as a sustainable and biodegradable product with the aim of noise pollution control has attracted the attention of many researchers. This work aims to study the acoustic behavior of porous absorbers made of natural Kenaf fibers. To this end, samples of sound absorber were fabricated with thicknesses of 10–40 mm at two different bulk densities of 150 and 200 kg/m3, and their sound absorption coefficient (SAC) was determined by standing wave sound impedance tube at different air gap cavities. A hybrid numerical-mathematical model was also proposed to investigate the acoustic behavior of the samples. To this end, a code was developed to simulate the 3D virtual structure of samples, and flow resistivity was calculated by numerically solving the flow of air in the structures. Tortuosity and two characteristic lengths were obtained using an inverse method programmed in MATLAB®. These parameters were then imported into the Johnson-Champoux-Allard (JCA) model to predict SACs at different frequencies. Afterward, considering the cost and sound absorption average (SAA), samples were optimized using factorial design. Consequently, the acoustic behavior of the optimized acoustic panels was investigated in the reverberation room in terms of reverberation time and random absorption coefficient. Moreover, in order to provide aesthetically and artistically pleasing appearance, the samples were covered with spacer fabrics, and their sound absorption behavior was also studied. The results revealed the promising sound absorption performance of Kenaf fibers. It was found that the SAC at low, mid, and high frequencies increases significantly with increasing the bulk density. The average of SACs for frequencies above 1250 Hz for samples of 40 mm thickness was found to be 0.95, while these values for samples of 30 and 20 mm thickness were respectively 0.85 and 0.7. The introduction of the air gap was found to improve the SAC at low-frequency bands and shift the peak of absorption toward low frequencies. Very good consistency was observed between the predicted and experimental data. The results of the statistical analysis suggested a thickness of 33 mm and a bulk density of 150 kg/m3 for the optimized panels. The results showed that the mean of SAC increased from 0.68 to 0.72 after covering the optimized panels with spacer fabrics.
Journal of Building Engineering, 2021
An increasing interest in the possibilities of converting agricultural wastes to value-added prod... more An increasing interest in the possibilities of converting agricultural wastes to value-added products has emerged. Annually, 200,000 tons of date palm waste are generated, which are charred or released as agricultural wastes. This work describes the efforts to fabricate low-cost sound-absorbing panels from date palm waste fibers and assess their performance for sound absorbing applications. Samples of different thicknesses (25, 35, 45, and 55 mm) and densities (125 and 175 kg/m3) were produced. The normal-incidence sound absorption coefficient was measured using the impedance tube and was modeled using both the Johnson-Champoux-Allard and the Attenborough models. The findings show that the samples with a thickness of 55 mm and a density of 175 kg/m3 have the highest sound absorbing performance. The acoustic behavior of this new material was investigated in a reverberation room. Moreover, the acoustic performance of the panels in a conference hall was modeled, assessing the improvements in its reverberation time (RT), early decay time (EDT), speech transmission index (STI), clarity (C80), and definition (D50). Finally, this paper shows that the acoustic performance of this material can be used to enhance room acoustics properties.
Applied Acoustics, 2021
Abstract An innovative natural fibro-granular composite made of kenaf fibers and waste rice husk ... more Abstract An innovative natural fibro-granular composite made of kenaf fibers and waste rice husk granules is developed and presented in this paper. The optimization of the sound absorption coefficient (SAC) of the composites was investigated through the impedance tube method. The central composite design (CCD) technique with response surface methodology (RSM) was used to design the experiments. A quadratic model was established to identify the effects of independent variables, including the thickness (20–60 mm), density (100–300 kg/m3), binder content (10–30 %w/w), and fiber to granule ratio (0.33–3) on the sound absorption average. The accuracy of the proposed model was assessed using ANOVA, and the results demonstrated that all the independent variables were significantly associated with sound absorption. The RSM-CCD model provided the combination for the optimized composite, i.e. thickness of 50 mm, density of 200 kg/m3, binder content of 15 %w/w, and fiber to granule ratio of 2.33. The fibro-granular composite prepared using the optimized results was further characterized in terms of SAC, airflow resistivity, tortuosity, and viscous and thermal characteristic lengths. The results pointed to the promising acoustic behavior of the optimized fibro-granular material. Results show that at all frequencies, the optimized fibro-granular sample provides higher sound absorption compared with samples made of 100% kenaf or 100% rice husk. The frequency-dependent SAC of the optimized material was also predicted by the empirical Delany-Bazley model and the phenomenological model of Johnson-Champoux-Allard, although this last model showed superior prediction performance.
Journal of Industrial Textiles, 2020
Among fibers with lignocellulosic origin, Kenaf fiber, because of its advantages and as a sustain... more Among fibers with lignocellulosic origin, Kenaf fiber, because of its advantages and as a sustainable alternative to synthetic fibers has received increasing attention for manufacturing hybrid composites with reasonable acoustical and physical properties. The present study deals with the impact of chemical treatment of Kenaf fibers on the overall properties of hybrid composites fabricated from these fibers. Also, the results from predictive analytical model of sound absorption for these composites were employed for comparison with the experimental findings. Kenaf fibers were treated at room temperature with 6% concentration of sodium hydroxide (NaOH) and 4 h immersion time. Having manufactured the composites with the treated and untreated fibers, the normal sound absorption coefficients and tensile strength properties of these sample composites were determined according to ISO 10534-2 and ASTM C1557 − 14, respectively. The SEM analysis of the treated and untreated fibers revealed th...
Applied Acoustics, 2020
This paper presents the finalized results of a recent project which investigated the aeromechanic... more This paper presents the finalized results of a recent project which investigated the aeromechanical aspects of aerodynamic force generation by making use of flapping wings. Flapping-wing experiments using small wings have some unique challenges posed by the low force level (∼ 1 N) and the cyclic wing motion. A tailored experimental water tunnel facility was developed for flapping wings operating at high reduced frequency with a complex two-dimensional and a three-dimensional motion profile. The experimental capability is demonstrated by the test cases of two-dimensional and three-dimensional flapping wings, designed according to a proposed notional nano-air-vehicle at a hovering condition. The features of the water tunnel, the geometric and kinematic parameters of the airfoils/wings, and the setups of the motion rigs for each test case are described. Measured forces and particle image velocimetry data are analyzed and cross-checked with the numerical results obtained from a code developed in-house. The comparisons of the experimental and numerical results show that the established experimental approach obtained a quantitatively reliable solution for the development of flapping wings and can serve for numerical validation of engineering tool developments. The investigation reveals that the kinematics of a rigid airfoil or wing is the dominant influence in the generation of aerodynamic forces, while the cross-section profile plays a secondary role. An asymmetric-wake-in-time is found behind the single airfoils and wings, which contributes to an asymmetry behavior of the resulting aerodynamic forces. In addition to the findings of single airfoils and wings, further analyses of the numerical and experimental results confirm that wing-wing interaction through the clap-fling mechanism can intensify the generation of the thrust force while accompanied by a small reduction in the overall propulsion efficiency.
American Journal of Men's Health, 2018
There is limited information on the specific psychosocial risks at work that can impact sexual fu... more There is limited information on the specific psychosocial risks at work that can impact sexual function. The general aim of this study was to investigate the effects of multiple dimensions of psychosocial work stressors on the male sexual function. This was a cross-sectional study conducted among 153 male nurses working in two hospitals in Iran. Sexual function and psychosocial job stressors were measured using the Persian version of the International Index of Erectile Function (P-IIEF) and the Persian version of the Health and Safety Executive (P-HSE) Management Standards Indicator Tool. The Persian version of the Work Ability Index (P-WAI) was used to assess the mediating effect of work ability on the relationship between overall stress and subscales of sexual function. The data were analyzed using Pearson product–moment correlation, one-way analysis of variance (ANOVA), and multiple linear regressions. The subscales of psychosocial job stressors, especially the subscale of role, ...
Heliyon, 2019
The present study examines the acoustic behavior sample composites made of date palm natural fibe... more The present study examines the acoustic behavior sample composites made of date palm natural fibers and polyvinyl alcohol. It also provides the comparison between the sound absorption coefficients obtained from the experimental tests and the ones predicted by the mathematical models. An impedance tube system was used to measure the normal sound absorption coefficient of the samples. Using the differential equation algorithm, the predicted sound absorption coefficient for the Johnson-Champoux-Allard model was also calculated. The sound absorption properties of samples increased significantly by increasing the frequency, and increasing the thickness of materials with constant density. Comparison of the data from the experimental tests and mathematical model showed that increasing the thickness of samples will make the predicted and tested values of acoustic absorption coefficient significantly comparable. Date palm fibers have a good potential for dissipating the energy of sound waves particularly when an air gap is introduced behind the sample and can be used as a new source for the fabrication of natural fiber reinforced composites.
Personality and Individual Differences, 2019
Abstract The aim of this study was to investigate the relationship between personality traits (ex... more Abstract The aim of this study was to investigate the relationship between personality traits (extraversion and neuroticism) and noise-induced annoyance. The effect of exposure to the single-frequency noise stimuli with low (65 dB) and high (85 dB) intensity on noise-induced annoyance levels of 169 students was studied. A tone generator software was used to generate noise stimuli with different frequencies. The noise induced annoyance levels were measured by the numerical rating scale recommended by ISO/TS 15666:2003. The Eysenck Personality Questionnaire-Revised Short Scale (EPQ-RS) which included a lie scale was employed to assess the dimensions such as personality, neuroticism, extraversion and psychoticism. Results revealed that for the low-intensity noise stimuli, at frequencies below 1000 Hz, the noise induced annoyance levels were equal for extroverts and introverts. But at frequencies above 1000 Hz, the levels for introverts were higher than extroverts. For the subjects exposed to the low-intensity noise stimuli, those with neurotic personality trait felt more noise induced annoyance than non-neurotic subjects at all frequencies. Exposure to high-intensity noise stimuli contributed to more noise induced annoyance among non-neurotic subjects within the whole frequency range. Also, exposure to low-intensity noise stimuli, resulted in higher levels of noise induced annoyance among female subjects for the whole frequency range. Noise annoyance may occur at any noise level, mainly due to different characteristics and personality traits of the individuals. Therefore, since the engineering control solutions often cannot mitigate the levels of annoyance caused by noise to the optimal level for many individuals, other influential factors such as individuals' personality traits should be taken into account.
Acoustics Australia, 2019
The remarkable properties of natural lignocellulosic fibers such as biodegradability, light weigh... more The remarkable properties of natural lignocellulosic fibers such as biodegradability, light weight, low density, low cost and non-toxicity as well as being an alternative to sound absorbers made of synthetic fibers have attracted many researchers in the field of acoustics. The purpose of the present study was to compare the estimated sound absorption coefficient of composite samples made of natural coconut fibers by using empirical models and comparing them with the results of experimental data. The normal sound absorption coefficients of the samples were measured with an impedance tube. The samples were fabricated in three different thicknesses (25, 35 and 45 mm) with air gaps behind them and had a constant density of 200 kg/m3. Next, calculations were made to estimate the absorption coefficients of the samples by coding in MATLAB and using the differential equation algorithm along with Delany–Bazley, Miki and Johnson–Champoux–Allard models. Based on the results, the sound absorption coefficients of the samples increased significantly with increasing frequency. Additionally, increasing the thickness of materials at constant densities increases the absorption of sound, especially at lower frequencies (< 1000 Hz). Comparison of the experimental data and estimations of the models showed that by increasing thickness, the predicted acoustic absorption coefficients for the samples become closer to the data from the experimental tests. At frequencies < 1000 Hz, increasing the air gap at the back of the sample to 3 cm would elevate the values of sound absorption coefficient. The samples made of coir fibers would effectively dissipate the energy of sound waves. It is noted that increasing the absorption of the sound in such materials is related to the longer depreciation process of thermal and viscous transfer between the air and the absorbing materials in the composite.
Health Scope, 2016
Background: Noise is one of the most important hazardous factors in industrial environments. Nois... more Background: Noise is one of the most important hazardous factors in industrial environments. Noise has many important negative effects on health; it can cause damage auditory, visual, neurological and psychological and hormonal systems, and physiological and cognitive functions. Objectives: The current study aimed to investigate the effects of noise exposure on changes in glucose and cortisol serum levels in adult male mice. Methods: A total of 24 adult male mice were randomly divided into two experimental and one control groups. One of the experimental groups was exposed to a noise pressure level of 90 dB played by Cool Edit software on a computer in a frequency range 700-5700 Hz, and the other one was exposed to the same noise and received an injection of streptozotocin (60 mg/kg). The experimental groups were exposed to the noise for 30 days, eight hours per day. Twenty-four hours after the end of the exposure period the fasting cortisol and glucose serum levels were measured in the mice of the three groups. Results: The study results showed a significant difference in the level of glucose in non-diabetic and diabetic groups exposed to the noise, compared to the control subjects (P < 0.002). In addition, there was a significant difference in the level of cortisol in non-diabetic and diabetic groups exposed to the noise, compared to the control groups (P < 0.002). Conclusions: The results showed that exposure to a 90 dB noise can increase cortisol and glucose levels. Hence, in work environments where people are exposed to noise, it is expected that such noises have a negative impact on them and the noise may increase cortisol and blood sugar levels.
Building and Environment, 2019
Abstract The present study deals with the acoustic performance of natural fibres originated from ... more Abstract The present study deals with the acoustic performance of natural fibres originated from the date palm empty fruit (DPEFB) fibres which is mainly considered as agricultural waste. The fibres were processed and fabricated to be sound absorber samples with two different densities of 100 kg/m3 and 200 kg/m3 and with thicknesses of 10–40 mm. The normal incidence absorption coefficients of the sound absorbers were measured using an impedance tube based on ISO 10534-2. The effects of fibre density and sample thickness are discussed. The findings reveal that for density of 100 kg/m3 the absorption coefficient is 0.6–0.8 above 1.5 kHz for the samples with the thickness of 20 mm and 30 mm. For the thickness of 40 mm, the values even reached the value of 0.9. The values can reach 0.7–0.8 above 1 kHz for the density of 200 kg/m3. Mathematical model using the optimized Delaney-Bazley model with Nelder-Mead simplex method is shown to successfully predict the sound absorption coefficient of the fibre samples. The Johnson-Champoux-Allard model follows the trend of the absorption coefficient, but underestimates the measured data at high frequencies above 2.5 kHz.
Journal of Mazandaran University of Medical Sciences, 2019
Background and purpose: Patient safety culture is essential in preventing patient injuries in hos... more Background and purpose: Patient safety culture is essential in preventing patient injuries in hospitals. Safety attitude is one of the valid tools used in assessment of safety culture among nurses. The purpose of this study was to investigate the nurses safety attitude and also understanding the effect of demographic characteristics, work shifts, and job demands on that. Materials and methods: This cross-sectional study was conducted in 325 nurses in Babol, north of Iran, 2016. Demographic and organizational information were recorded. The Safety Attitude Questionnaire (SAQ) and Job Content Questionnaire (JCQ) were used. Data analysis was done using regression analysis in SPSS V24. Results: The average values for psychological and physical demands of nurses were 32.7±9.4 and 8.8±2.8, respectively. According to the SAQ, the dimensions of stress recognition (73.6 ±17.9) and perception of management (48.8±16.2) were found with the highest and lowest mean scores, respectively. Also, regr...
Applied Acoustics
In this study, hybrid composites made of polyurethane (PU) matrix and natural kenaf fiber filler ... more In this study, hybrid composites made of polyurethane (PU) matrix and natural kenaf fiber filler were designed and fabricated. The Response Surface Methodology (RSM) optimization approach coupled with a Central Composite Design (CCD) was used to design the experiments and optimize the parameters affecting the acoustic performance of the samples in the low and mid-frequency ranges. The acoustic performance of the samples was investigated using the impedance tube method. Additionally, the acoustic performance was predicted using a developed Quadratic model as well as the Delany-Bazley (DB) and Johnson-Champoux-Allard (JCA) models. The results showed that the acoustic absorption of neat PU foam is remarkably improved at all frequencies with the addition of kenaf fibers as the filler. It was found that the acoustic performance of the composite samples is optimal when the added amount of kenaf fibers to the polymer matrix and fiber length are 1.2 wt% and 8 mm, respectively. The sound absorption average (SAA) of the optimized composite and neat PU foam was calculated as 0.65 and 0.48, respectively i.e., an increase of 35.4 %. The Quadratic model showed very high accuracy for the prediction of the SAA of the optimized sample. The JCA model provided higher accuracy for the prediction of the frequencydependent sound absorption coefficient of the composites as compared with the DB model.
Journal of Environmental Health Science and Engineering
Journal of Natural Fibers, Feb 20, 2023
International Journal of Environmental Science and Technology
In recent years, rapid economic development and urbanization have led to severe environmental pro... more In recent years, rapid economic development and urbanization have led to severe environmental problems such as noise pollution. The use of fibrous porous materials is considered to be an effective method to control noise pollution. This study investigates the morphological and acoustical characteristics of fibrous materials made of aluminosilicate fibers (ASFs). To this end, morphological and structural properties of samples were investigated using field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) method. The effect of sample thickness and air gap was experimentally studied using the impedance tube method in the frequency range of 63-6300 Hz. The frequency-dependent acoustic behavior of the samples was also predicted using the empirical models of Delany-Bazley (D-B), Garai-Pompoli (G-P), and the proposed revised models of D-B and G-P. The XRD patterns showed that the main phases of the ASF are quartz, tridymite, and mullite. The BET analysis confirmed that the samples are classified as macro-porous. It was found that with the increase of the sample thickness sound absorption coefficient (SAC) increases at low frequencies. The averages of SACs for samples with thicknesses of 10 and 25 mm at low frequencies were 0.17 and 0.32, respectively. These values for the middle frequencies were 0.78 and 0.80, and for high frequencies were 0.83 and 0.84, respectively. Additionally, it was observed that with the increase of air gap depth, SAC enhances at low-frequency bands, and the SAC peak shifts toward the lower frequencies. Additionally, excellent agreement was observed between the experimentally measured SACs and those predicted by the revised D-B and G-P models.
springer, 2022
In recent years, rapid economic development and urbanization have led to severe environmental pro... more In recent years, rapid economic development and urbanization have led to severe environmental problems such as noise pollution. The use of fibrous porous materials is considered to be an effective method to control noise pollution. This study investigates the morphological and acoustical characteristics of fibrous materials made of aluminosilicate fibers (ASFs). To this end, morphological and structural properties of samples were investigated using field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) method. The effect of sample thickness and air gap was experimentally studied using the impedance tube method in the frequency range of 63-6300 Hz. The frequency-dependent acoustic behavior of the samples was also predicted using the empirical models of Delany-Bazley (D-B), Garai-Pompoli (G-P), and the proposed revised models of D-B and G-P. The XRD patterns showed that the main phases of the ASF are quartz, tridymite, and mullite. The BET analysis confirmed that the samples are classified as macro-porous. It was found that with the increase of the sample thickness sound absorption coefficient (SAC) increases at low frequencies. The averages of SACs for samples with thicknesses of 10 and 25 mm at low frequencies were 0.17 and 0.32, respectively. These values for the middle frequencies were 0.78 and 0.80, and for high frequencies were 0.83 and 0.84, respectively. Additionally, it was observed that with the increase of air gap depth, SAC enhances at low-frequency bands, and the SAC peak shifts toward the lower frequencies. Additionally, excellent agreement was observed between the experimentally measured SACs and those predicted by the revised D-B and G-P models.
Building and Environment, 2022
Work, 2022
BACKGROUND: Exposure to traffic noise could play an important part in inducing psychological diso... more BACKGROUND: Exposure to traffic noise could play an important part in inducing psychological disorders which in turn can affect individuals’ cognitive and mental performance. OBJECTIVE: The aim of this study was to determine the effect of traffic noise exposure on the cognitive performance with regard to subjects’ personality traits. METHODS: Sixty students with normal hearing and vision took part in this experimental study. In order to simulate the traffic noise condition of Tehran, the noise from several busy streets was first carefully recorded. Later on, the subjects were exposed to this recorded noise in an anechoic chamber. Also, the NEO-five factor inventory questionnaire and the continuous performance test were used to assess personality traits and cognitive performance of participants respectively. RESULTS: The results showed that the cognitive features of the study, such as reaction time and the number of commission/omission errors in continuous performance testing increas...
Building and Environment, 2022
Building and Environment, 2020
Abstract The use of natural fibers in the buildings and construction industries as a sustainable ... more Abstract The use of natural fibers in the buildings and construction industries as a sustainable and biodegradable product with the aim of noise pollution control has attracted the attention of many researchers. This work aims to study the acoustic behavior of porous absorbers made of natural Kenaf fibers. To this end, samples of sound absorber were fabricated with thicknesses of 10–40 mm at two different bulk densities of 150 and 200 kg/m3, and their sound absorption coefficient (SAC) was determined by standing wave sound impedance tube at different air gap cavities. A hybrid numerical-mathematical model was also proposed to investigate the acoustic behavior of the samples. To this end, a code was developed to simulate the 3D virtual structure of samples, and flow resistivity was calculated by numerically solving the flow of air in the structures. Tortuosity and two characteristic lengths were obtained using an inverse method programmed in MATLAB®. These parameters were then imported into the Johnson-Champoux-Allard (JCA) model to predict SACs at different frequencies. Afterward, considering the cost and sound absorption average (SAA), samples were optimized using factorial design. Consequently, the acoustic behavior of the optimized acoustic panels was investigated in the reverberation room in terms of reverberation time and random absorption coefficient. Moreover, in order to provide aesthetically and artistically pleasing appearance, the samples were covered with spacer fabrics, and their sound absorption behavior was also studied. The results revealed the promising sound absorption performance of Kenaf fibers. It was found that the SAC at low, mid, and high frequencies increases significantly with increasing the bulk density. The average of SACs for frequencies above 1250 Hz for samples of 40 mm thickness was found to be 0.95, while these values for samples of 30 and 20 mm thickness were respectively 0.85 and 0.7. The introduction of the air gap was found to improve the SAC at low-frequency bands and shift the peak of absorption toward low frequencies. Very good consistency was observed between the predicted and experimental data. The results of the statistical analysis suggested a thickness of 33 mm and a bulk density of 150 kg/m3 for the optimized panels. The results showed that the mean of SAC increased from 0.68 to 0.72 after covering the optimized panels with spacer fabrics.
Journal of Building Engineering, 2021
An increasing interest in the possibilities of converting agricultural wastes to value-added prod... more An increasing interest in the possibilities of converting agricultural wastes to value-added products has emerged. Annually, 200,000 tons of date palm waste are generated, which are charred or released as agricultural wastes. This work describes the efforts to fabricate low-cost sound-absorbing panels from date palm waste fibers and assess their performance for sound absorbing applications. Samples of different thicknesses (25, 35, 45, and 55 mm) and densities (125 and 175 kg/m3) were produced. The normal-incidence sound absorption coefficient was measured using the impedance tube and was modeled using both the Johnson-Champoux-Allard and the Attenborough models. The findings show that the samples with a thickness of 55 mm and a density of 175 kg/m3 have the highest sound absorbing performance. The acoustic behavior of this new material was investigated in a reverberation room. Moreover, the acoustic performance of the panels in a conference hall was modeled, assessing the improvements in its reverberation time (RT), early decay time (EDT), speech transmission index (STI), clarity (C80), and definition (D50). Finally, this paper shows that the acoustic performance of this material can be used to enhance room acoustics properties.
Applied Acoustics, 2021
Abstract An innovative natural fibro-granular composite made of kenaf fibers and waste rice husk ... more Abstract An innovative natural fibro-granular composite made of kenaf fibers and waste rice husk granules is developed and presented in this paper. The optimization of the sound absorption coefficient (SAC) of the composites was investigated through the impedance tube method. The central composite design (CCD) technique with response surface methodology (RSM) was used to design the experiments. A quadratic model was established to identify the effects of independent variables, including the thickness (20–60 mm), density (100–300 kg/m3), binder content (10–30 %w/w), and fiber to granule ratio (0.33–3) on the sound absorption average. The accuracy of the proposed model was assessed using ANOVA, and the results demonstrated that all the independent variables were significantly associated with sound absorption. The RSM-CCD model provided the combination for the optimized composite, i.e. thickness of 50 mm, density of 200 kg/m3, binder content of 15 %w/w, and fiber to granule ratio of 2.33. The fibro-granular composite prepared using the optimized results was further characterized in terms of SAC, airflow resistivity, tortuosity, and viscous and thermal characteristic lengths. The results pointed to the promising acoustic behavior of the optimized fibro-granular material. Results show that at all frequencies, the optimized fibro-granular sample provides higher sound absorption compared with samples made of 100% kenaf or 100% rice husk. The frequency-dependent SAC of the optimized material was also predicted by the empirical Delany-Bazley model and the phenomenological model of Johnson-Champoux-Allard, although this last model showed superior prediction performance.
Journal of Industrial Textiles, 2020
Among fibers with lignocellulosic origin, Kenaf fiber, because of its advantages and as a sustain... more Among fibers with lignocellulosic origin, Kenaf fiber, because of its advantages and as a sustainable alternative to synthetic fibers has received increasing attention for manufacturing hybrid composites with reasonable acoustical and physical properties. The present study deals with the impact of chemical treatment of Kenaf fibers on the overall properties of hybrid composites fabricated from these fibers. Also, the results from predictive analytical model of sound absorption for these composites were employed for comparison with the experimental findings. Kenaf fibers were treated at room temperature with 6% concentration of sodium hydroxide (NaOH) and 4 h immersion time. Having manufactured the composites with the treated and untreated fibers, the normal sound absorption coefficients and tensile strength properties of these sample composites were determined according to ISO 10534-2 and ASTM C1557 − 14, respectively. The SEM analysis of the treated and untreated fibers revealed th...
Applied Acoustics, 2020
This paper presents the finalized results of a recent project which investigated the aeromechanic... more This paper presents the finalized results of a recent project which investigated the aeromechanical aspects of aerodynamic force generation by making use of flapping wings. Flapping-wing experiments using small wings have some unique challenges posed by the low force level (∼ 1 N) and the cyclic wing motion. A tailored experimental water tunnel facility was developed for flapping wings operating at high reduced frequency with a complex two-dimensional and a three-dimensional motion profile. The experimental capability is demonstrated by the test cases of two-dimensional and three-dimensional flapping wings, designed according to a proposed notional nano-air-vehicle at a hovering condition. The features of the water tunnel, the geometric and kinematic parameters of the airfoils/wings, and the setups of the motion rigs for each test case are described. Measured forces and particle image velocimetry data are analyzed and cross-checked with the numerical results obtained from a code developed in-house. The comparisons of the experimental and numerical results show that the established experimental approach obtained a quantitatively reliable solution for the development of flapping wings and can serve for numerical validation of engineering tool developments. The investigation reveals that the kinematics of a rigid airfoil or wing is the dominant influence in the generation of aerodynamic forces, while the cross-section profile plays a secondary role. An asymmetric-wake-in-time is found behind the single airfoils and wings, which contributes to an asymmetry behavior of the resulting aerodynamic forces. In addition to the findings of single airfoils and wings, further analyses of the numerical and experimental results confirm that wing-wing interaction through the clap-fling mechanism can intensify the generation of the thrust force while accompanied by a small reduction in the overall propulsion efficiency.
American Journal of Men's Health, 2018
There is limited information on the specific psychosocial risks at work that can impact sexual fu... more There is limited information on the specific psychosocial risks at work that can impact sexual function. The general aim of this study was to investigate the effects of multiple dimensions of psychosocial work stressors on the male sexual function. This was a cross-sectional study conducted among 153 male nurses working in two hospitals in Iran. Sexual function and psychosocial job stressors were measured using the Persian version of the International Index of Erectile Function (P-IIEF) and the Persian version of the Health and Safety Executive (P-HSE) Management Standards Indicator Tool. The Persian version of the Work Ability Index (P-WAI) was used to assess the mediating effect of work ability on the relationship between overall stress and subscales of sexual function. The data were analyzed using Pearson product–moment correlation, one-way analysis of variance (ANOVA), and multiple linear regressions. The subscales of psychosocial job stressors, especially the subscale of role, ...
Heliyon, 2019
The present study examines the acoustic behavior sample composites made of date palm natural fibe... more The present study examines the acoustic behavior sample composites made of date palm natural fibers and polyvinyl alcohol. It also provides the comparison between the sound absorption coefficients obtained from the experimental tests and the ones predicted by the mathematical models. An impedance tube system was used to measure the normal sound absorption coefficient of the samples. Using the differential equation algorithm, the predicted sound absorption coefficient for the Johnson-Champoux-Allard model was also calculated. The sound absorption properties of samples increased significantly by increasing the frequency, and increasing the thickness of materials with constant density. Comparison of the data from the experimental tests and mathematical model showed that increasing the thickness of samples will make the predicted and tested values of acoustic absorption coefficient significantly comparable. Date palm fibers have a good potential for dissipating the energy of sound waves particularly when an air gap is introduced behind the sample and can be used as a new source for the fabrication of natural fiber reinforced composites.
Personality and Individual Differences, 2019
Abstract The aim of this study was to investigate the relationship between personality traits (ex... more Abstract The aim of this study was to investigate the relationship between personality traits (extraversion and neuroticism) and noise-induced annoyance. The effect of exposure to the single-frequency noise stimuli with low (65 dB) and high (85 dB) intensity on noise-induced annoyance levels of 169 students was studied. A tone generator software was used to generate noise stimuli with different frequencies. The noise induced annoyance levels were measured by the numerical rating scale recommended by ISO/TS 15666:2003. The Eysenck Personality Questionnaire-Revised Short Scale (EPQ-RS) which included a lie scale was employed to assess the dimensions such as personality, neuroticism, extraversion and psychoticism. Results revealed that for the low-intensity noise stimuli, at frequencies below 1000 Hz, the noise induced annoyance levels were equal for extroverts and introverts. But at frequencies above 1000 Hz, the levels for introverts were higher than extroverts. For the subjects exposed to the low-intensity noise stimuli, those with neurotic personality trait felt more noise induced annoyance than non-neurotic subjects at all frequencies. Exposure to high-intensity noise stimuli contributed to more noise induced annoyance among non-neurotic subjects within the whole frequency range. Also, exposure to low-intensity noise stimuli, resulted in higher levels of noise induced annoyance among female subjects for the whole frequency range. Noise annoyance may occur at any noise level, mainly due to different characteristics and personality traits of the individuals. Therefore, since the engineering control solutions often cannot mitigate the levels of annoyance caused by noise to the optimal level for many individuals, other influential factors such as individuals' personality traits should be taken into account.
Acoustics Australia, 2019
The remarkable properties of natural lignocellulosic fibers such as biodegradability, light weigh... more The remarkable properties of natural lignocellulosic fibers such as biodegradability, light weight, low density, low cost and non-toxicity as well as being an alternative to sound absorbers made of synthetic fibers have attracted many researchers in the field of acoustics. The purpose of the present study was to compare the estimated sound absorption coefficient of composite samples made of natural coconut fibers by using empirical models and comparing them with the results of experimental data. The normal sound absorption coefficients of the samples were measured with an impedance tube. The samples were fabricated in three different thicknesses (25, 35 and 45 mm) with air gaps behind them and had a constant density of 200 kg/m3. Next, calculations were made to estimate the absorption coefficients of the samples by coding in MATLAB and using the differential equation algorithm along with Delany–Bazley, Miki and Johnson–Champoux–Allard models. Based on the results, the sound absorption coefficients of the samples increased significantly with increasing frequency. Additionally, increasing the thickness of materials at constant densities increases the absorption of sound, especially at lower frequencies (< 1000 Hz). Comparison of the experimental data and estimations of the models showed that by increasing thickness, the predicted acoustic absorption coefficients for the samples become closer to the data from the experimental tests. At frequencies < 1000 Hz, increasing the air gap at the back of the sample to 3 cm would elevate the values of sound absorption coefficient. The samples made of coir fibers would effectively dissipate the energy of sound waves. It is noted that increasing the absorption of the sound in such materials is related to the longer depreciation process of thermal and viscous transfer between the air and the absorbing materials in the composite.
Health Scope, 2016
Background: Noise is one of the most important hazardous factors in industrial environments. Nois... more Background: Noise is one of the most important hazardous factors in industrial environments. Noise has many important negative effects on health; it can cause damage auditory, visual, neurological and psychological and hormonal systems, and physiological and cognitive functions. Objectives: The current study aimed to investigate the effects of noise exposure on changes in glucose and cortisol serum levels in adult male mice. Methods: A total of 24 adult male mice were randomly divided into two experimental and one control groups. One of the experimental groups was exposed to a noise pressure level of 90 dB played by Cool Edit software on a computer in a frequency range 700-5700 Hz, and the other one was exposed to the same noise and received an injection of streptozotocin (60 mg/kg). The experimental groups were exposed to the noise for 30 days, eight hours per day. Twenty-four hours after the end of the exposure period the fasting cortisol and glucose serum levels were measured in the mice of the three groups. Results: The study results showed a significant difference in the level of glucose in non-diabetic and diabetic groups exposed to the noise, compared to the control subjects (P < 0.002). In addition, there was a significant difference in the level of cortisol in non-diabetic and diabetic groups exposed to the noise, compared to the control groups (P < 0.002). Conclusions: The results showed that exposure to a 90 dB noise can increase cortisol and glucose levels. Hence, in work environments where people are exposed to noise, it is expected that such noises have a negative impact on them and the noise may increase cortisol and blood sugar levels.
Building and Environment, 2019
Abstract The present study deals with the acoustic performance of natural fibres originated from ... more Abstract The present study deals with the acoustic performance of natural fibres originated from the date palm empty fruit (DPEFB) fibres which is mainly considered as agricultural waste. The fibres were processed and fabricated to be sound absorber samples with two different densities of 100 kg/m3 and 200 kg/m3 and with thicknesses of 10–40 mm. The normal incidence absorption coefficients of the sound absorbers were measured using an impedance tube based on ISO 10534-2. The effects of fibre density and sample thickness are discussed. The findings reveal that for density of 100 kg/m3 the absorption coefficient is 0.6–0.8 above 1.5 kHz for the samples with the thickness of 20 mm and 30 mm. For the thickness of 40 mm, the values even reached the value of 0.9. The values can reach 0.7–0.8 above 1 kHz for the density of 200 kg/m3. Mathematical model using the optimized Delaney-Bazley model with Nelder-Mead simplex method is shown to successfully predict the sound absorption coefficient of the fibre samples. The Johnson-Champoux-Allard model follows the trend of the absorption coefficient, but underestimates the measured data at high frequencies above 2.5 kHz.
Journal of Mazandaran University of Medical Sciences, 2019
Background and purpose: Patient safety culture is essential in preventing patient injuries in hos... more Background and purpose: Patient safety culture is essential in preventing patient injuries in hospitals. Safety attitude is one of the valid tools used in assessment of safety culture among nurses. The purpose of this study was to investigate the nurses safety attitude and also understanding the effect of demographic characteristics, work shifts, and job demands on that. Materials and methods: This cross-sectional study was conducted in 325 nurses in Babol, north of Iran, 2016. Demographic and organizational information were recorded. The Safety Attitude Questionnaire (SAQ) and Job Content Questionnaire (JCQ) were used. Data analysis was done using regression analysis in SPSS V24. Results: The average values for psychological and physical demands of nurses were 32.7±9.4 and 8.8±2.8, respectively. According to the SAQ, the dimensions of stress recognition (73.6 ±17.9) and perception of management (48.8±16.2) were found with the highest and lowest mean scores, respectively. Also, regr...