ABSTRACT
Electrospinning is a method of nanofiber filter media production. By this method, it is possible to produce media with nanofiber in the range of nanometer to micrometer. Nanofibrous media provide a large specific surface area in a finite volume thus they are suitable for filtration applications. In this study, nanofiber non-woven membranes production of Nylon-6 by electrospinning method is investigated. It is demonstrated that the total filter efficiency and pressure drop increases by increasing the thickness of filer media. The objective of this experimental study was to find out the effect nylon concentration and thickness of nanofilter media.Samples by different Nylon-6 concentrations and time of electrospinning were made. The filtration characterizations of these media were investigated in different laboratory conditions. The SEM micrographs of specimens treated by ImageJ software reveal that the porosity passes by a minimum at 10% concentration. The diameter of nanofiber varied in the range of 47 to 89 nm when the nylon concentration varied from 7.5% to 15% respectively. The efficiency was improved more than three times by electrospinning operation for all ' three concentration samples. Our results showed that the highest efficiency obtained hi this study was 99.96% belonging to 10% Nylon-6 concentration for 45 minutes electrospinning time
ABSTRACT
Eighty five percent of accidents can be attributed to unsafe acts. Eighty five to ninety eight percent of workplace injuries caused by unsafe acts are due to attitude, behavior and culture. Safety climate is a multi-dimensional structure that describes the attitude and the correct priority of the people towards the safety at work. To assess safety climate, a valid and reliable tool is needed. The aim of this study was developing a psychometric questionnaire to assess safety climate in Iran. Using safety literature and other safety climate questionnaire, a 96-item questionnaire was provided. Face validity, content validity ratio and index, construct validity, internal consistency reliability and test-retest reliability were investigated on 550 industrial employees .After validity index survey 43 items questionnaire were obtained. Principal factors were extracted using exploratory factor analysis by Varimax rotation method. To check the reliability of the questionnaire, Cronbach's alpha coefficients and Pearson correlation coefficient was used. For the face validity, CVR [78.5%] and CVI [0.75] related to safety climate designed questionnaire to be acceptable, eleven factors were extracted that covered 58.85 percent of total variance. Cronbach's alpha for most factors more than 0.7 were calculated and Spearman coefficient showed significant correlation between test and retest results. The Safety "Climate Assessment Questionnaire" which has been designed for 43 items and 11 factors has appropriate validity and reliability and can be used to assess the safety climate.
ABSTRACT
The removal of fine particles less than 2.5 microm in diameter generated from industrial plants represents a serious challenge in air pollution abatement. These particles can penetrate deeply into the lungs and are difficult to remove by cyclones, electrostatic precipitators, and other conventional separation devices. In this paper, the influence of acoustic waves on removing aerosol particles from gas flue is studied. The mechanism of this effect includes the coagulation of nanometer particles to each other and forms larger particles. Moreover, these particles adhere to the wall of the test-rig pipe by the acoustic precipitation mechanism. Therefore, the particles are separated from the gas flue. Experiments are carried out on particle sized in the range of 260-3000 nm. Micro-sphere particles immersed in the air are subjected to homogeneous plane standing-waves at frequencies ranging from 100 Hz up to 2 kHz and a pressure level of 120 to 150 dB. At high pressure levels, the results indicate that the system has high efficiency for removing fine particles