Using the Absorptive-Dissipative Silencer in Air Conditioning Systems of an Office Environment in Order to Provide Acoustic Comfort

Air conditioning systems are the main source of background low frequency noise in administrative buildings, restaurants, classrooms, and hotels. There are different ways to reduce the low frequency noise. Silencers are generic tools which are utilized for controlling noise produced by air conditioning systems. Sound assessment and frequency analysis were performed in accordance with standard methods to evaluate the exposure of workers in separate work stations. In the next step, an absorptive- dissipative silencer which its inner side was covered by convoluted acoustical foam was implemented in the ventilation system. The exposure of employees was re-evaluated. Moreover, Preferred Noise Criterion (PNC) and Speech Interference Level (SIL) were two acoustic indices used for assessing the effectiveness of the silencer. Before implementing the silencer, the sound pressure level in the rooms was between 57.8 and 61.1dBA with a peak frequency at 125Hz. The implemented silencer with dimensions of 1.4 ×1×1m, and inlet and outlet area of 0.45×0.45m was able to reduce the sound pressure level of about 13 to 14.2dB. Further, the PNC and the SIL indices were reduced to 14.33 and 15.31dB, respectively. The implemented absorptive- dissipative silencer reduced the sound pressure level of about 13.6dBA. Moreover, PNC and SIL indices are two important indices which can be used for assessing the level of comfort in office buildings

Investigation Sleep Quality and Its Effective Factors in Shahroud Firefighters

Background: Physical and mental health are significantly related to adequate sleep and sleep satisfaction. Sleeping disorder is one of the most severe occupational risks for modern firefighting services. Thus, the current study was conducted to evaluate sleep quality and its effective factors in firefighters‏. Methods: This descriptive-analytical study was carried out among all firefighters in Shahroud, Iran, in 2017. All data were collected by a two-part questionnaire containing demographic information and the Pittsburgh Sleep Quality Index (PSQI), which was completed while interviewing the participants. Finally, data were analyzed by SPSS software. Results: PSQI was obtained as 7.65±2.98, which classified into "Low Quality." Sleep latency, sleep duration, sleep disturbances and day-time dysfunction had a significant relationship with sleep quality (P<0.05). Moreover, the results demonstrated that PSQL score had a strong relationship with age and BMI (F-model= 21.78 and P<0.001 and r=0.701). Conclusions: Results of this study showed that firefighters have not adequate sleep quality. It is suggested to participate young people in missions since their sleep quality was better. Also, weight loss is suggested for overweight people in order to improve their sleep quality‏

Investigation Sleep Quality and Its Effective Factors in Shahroud Firefighters

Background: Physical and mental health are significantly related to adequate sleep and sleep satisfaction. Sleeping disorder is one of the most severe occupational risks for modern firefighting services. Thus, the current study was conducted to evaluate sleep quality and its effective factors in firefighters‏. Methods: This descriptive-analytical study was carried out among all firefighters in Shahroud, Iran, in 2017. All data were collected by a two-part questionnaire containing demographic information and the Pittsburgh Sleep Quality Index (PSQI), which was completed while interviewing the participants. Finally, data were analyzed by SPSS software. Results: PSQI was obtained as 7.65±2.98, which classified into "Low Quality." Sleep latency, sleep duration, sleep disturbances and day-time dysfunction had a significant relationship with sleep quality (P<0.05). Moreover, the results demonstrated that PSQL score had a strong relationship with age and BMI (F-model= 21.78 and P<0.001 and r=0.701). Conclusions: Results of this study showed that firefighters have not adequate sleep quality. It is suggested to participate young people in missions since their sleep quality was better. Also, weight loss is suggested for overweight people in order to improve their sleep quality‏

Response of Grain Yield and Yield Components of Triticale to Sowing Date and Plant Density

In order to study of sowing date and plant density on Triticale (Tritico secale), a field experiment was carried out under dry farming in the Rice Research Institute of Iran, during 2008-2009. The experiment was conducted as a RCBD based split-plot design with three replications. Experimental treatments included: Four sowing date (Sept. 21, Oct. 1, Oct. 10, and Oct. 20) as main plot and four plant density (275, 350, 425 and 500 plant/m2 ) composed of as sub plots, respectively. Results indicated that plant density was significant effect on tiller number/plant. The highest number (13.6 tiller/ plant) was obtained in 275 plant/m2 seed density. The results showed, spike length and plant dry matter was affected only by sowing date. The highest dry matter and the longest spike were produced on Sep. 21. Result of the experiment revealed that grain yield, spike number per plant and harvest index significantly affected by sowing date× plant density interaction. However, planting 500 plant/m2 in Sept. 21 resulted to highest (5863 Kg ha-1) grain yield and 275 plant/m2 seed in Oct. 21 resulted the lowest (3351.08 Kg ha-1)