scholarly journals Electrocharging face masks with corona discharge treatment

2021 ◽  
Vol 477 (2251) ◽  
pp. 20210062
Author(s):  
M. M. Bandi ◽  
N. Ishizu ◽  
H.-B. Kang
Keyword(s):  
Corona Discharge ◽  
Experimental Method ◽  
Electric Discharge ◽  
Structural Integrity ◽  
Filtration Efficiency ◽  
The Other ◽  
Ion Adsorption ◽  
Charge Retention ◽  
Discharge Treatment ◽  
Multiple Cycles

We detail an experimental method to electrocharge N95 facepiece respirators and face masks (FMs) made from a variety of fabrics (including non-woven polymer and knitted cloth) using corona discharge treatment (CDT). We present practical designs to construct a CDT system from commonly available parts and detail calibrations performed on different fabrics to study their electrocharging characteristics. After confirming the post-CDT structural integrity of fabrics, measurements showed that all non-woven polymer electret and only some knitted cloth fabrics are capable of charge retention. Whereas polymeric fabrics follow the well-known isothermal charging route, ion adsorption causes electrocharging in knitted cloth fabrics. Filtration tests demonstrate improved steady filtration efficiency in non-woven polymer electret filters. On the other hand, knitted cloth fabric filters capable of charge retention start with improved filtration efficiency which decays in time over up to 7 h depending on the fabric type, with filtration efficiency tracking the electric discharge. A rapid recharge for a few seconds ensures FM reuse over multiple cycles without degradation.

IV.—The Mammoth in Siberia

1880 ◽  
Vol 7 (9) ◽  
pp. 408-414
Author(s):  
Henry H. Howorth
Keyword(s):  
Experimental Method ◽  
The Other ◽  
Boundary Line ◽  
Modern Development ◽  
The Subject ◽  
The One ◽  
Neutral Ground

The overlapping of the sciences is made the subject of much rhetorical writing now-a-days, and its appreciation is one of the most prominent signs of the modern development of the doctrine of Continuity which has been so fruitful in the Philosophy of Discovery. The boundary-line which once separated the geologist and ethnologist has in consequence of this development entirely disappeared, and every one now admits as a postulate that between the two sciences there is a stretch of neutral ground belonging to neither exclusively, and where the students of each must of necessity reap if their harvest is to be complete. Not only so, but it is beginning to be seen that the methods and the directions of the arguments in each science being more or less different—the one partaking much more of the historical, and the other of the experimental method—that it is well that where they overlap the results of each should be closely compared, and thus not only secure a double modicum of certitude, but also suggest fresh veins of untried material where we may put in our mattock with renewed hope of solving some apparently hopeless problems.

scholarly journals THE MODELING OF SPILLS RESULTING FROM THE CATASTROPHIC FAILURE OF ABOVE GROUND STORAGE TANKS AND THE DEVELOPMENT OF MITIGATION

2008 ◽  
Vol 2008 (1) ◽  
pp. 949-956
Author(s):  
W. Atherton ◽  
J. W. Ash ◽  
R. M. Alkhaddar
Keyword(s):  
Large Scale ◽  
Structural Integrity ◽  
Oil Spills ◽  
Health And Safety ◽  
The Other ◽  
Catastrophic Failure ◽  
Storage Tanks ◽  
Modes Of Failure ◽  
Mode Of Failure ◽  
Mitigation Technique

ABSTRACT The risk of accidents involving the catastrophic failure of storage tanks is estimated to be low, in the region of 5 × l0−6 per tank year. However, recent accidents involving major oil spills at storage facilities located in Belgium (2004) along with USA and England (2005) have shown that tank failures do nevertheless occur. Causalities of such events vary; the consequences however are ordinarily the same, incurring environmental, financial and infrastructure losses. The normal mitigation technique employed to prevent such losses is secondary containment, usually in the form of a bund wall or earthen dyke. Researchers have investigated the reliability of such methods, examining the effects of tank failure, both theoretically and experimentally in terms of loss of containment. A United Kingdom Health and Safety Executive (HSE) review conducted in 1997 concluded that the then available data was limited and focussed attention on the work of Greenspan and Johansson (1981) and the later work of Trobojevic and Slater (1989). This led to the HSE commissioning Liverpool John Moores University (LIMU) in 2003 to undertake a large-scale spill-modelling program with the aim of quantifying the level of overtopping and the magnitudes of the dynamic pressures on the bunds. The study examined the effect of axisymmetric releases on a total of 96 tank and bund arrangements. Such losses have proven to be significant and in some cases the nature of the dynamic pressures has brought in to question the structural integrity of the bunds themselves. Research has since concentrated on modelling alternative modes of failure, such as directional releases, which could be considered to be the more common mode of failure likely to be encountered. The conclusions to this work have generated additional research to investigate possible methods of mitigation that could be incorporated into the design of facilities with the ultimate aim of further reducing losses in the event of tank failure. Two promising methods have been identified, one involving modification to the primary containment (tank) with the other being a change to the design of the profile of the secondary containment (bund wall).

scholarly journals Inward and outward effectiveness of cloth masks, a surgical mask, and a face shield

2020 ◽  
Author(s):  
Jin Pan ◽  
Charbel Harb ◽  
Weinan Leng ◽  
Linsey C. Marr
Keyword(s):  
Particle Size ◽  
Respiratory Tract ◽  
Filtration Efficiency ◽  
The Other ◽  
Woven Fabric ◽  
Protection Efficiency ◽  
Overall Efficiency

AbstractWe evaluated the effectiveness of 11 face coverings for material filtration efficiency, inward protection efficiency on a manikin, and outward protection efficiency on a manikin. At the most penetrating particle size, the vacuum bag, microfiber cloth, and surgical mask had material filtration efficiencies >50%, while the other materials had much lower filtration efficiencies. However, these efficiencies increased rapidly with particle size, and many materials had efficiencies >50% at 2 μm and >75% at 5 μm. The vacuum bag performed best, with efficiencies of 54-96% for all three metrics, depending on particle size. The thin acrylic and face shield performed worst. Inward protection efficiency and outward protection efficiency were similar for many masks; the two efficiencies diverged for stiffer materials and those worn more loosely (e.g., bandana) or more tightly (e.g., wrapped around the head) compared to a standard earloop mask. Discrepancies between material filtration efficiency and inward/outward protection efficiency indicated that the fit of the mask was important. We calculated that the particle size most likely to deposit in the respiratory tract when wearing a mask is ∼2 μm. Based on these findings, we recommend a three-layer mask consisting of outer layers of a flexible, tightly woven fabric and an inner layer consisting of a material designed to filter out particles. This combination should produce an overall efficiency of >70% at the most penetrating particle size and >90% for particles 1 μm and larger if the mask fits well.

scholarly journals Modelling the impact of microbial contamination of fuel filtration efficiency

2017 ◽  
Vol 169 (2) ◽  
pp. 133-136
Author(s):  
Rafał KRAKOWSKI
Keyword(s):  
Numerical Model ◽  
Microbial Contamination ◽  
Petroleum Products ◽  
Filtration Efficiency ◽  
The Other ◽  
Entire System ◽  
Factors Influencing ◽  
Three Stages ◽  
The Impact ◽  
Growth Of Bacteria

In this paper the concept of filtration and the problem of microbial contamination occurring in the fuels and oils was presented. Then the factors influencing the growth of bacteria in petroleum products were described in detail. In the next part of the article modeling of the impact of fuel microbial contamination on filtration efficiency was performed. The modeling presented in the article is an example showing how undesirable phenomenon is the microbial contamination and how pollution affects the other elements of the entire system. As part of the modeling, numerical model of filtration with the solution was presented. Then analysis results on the basis of the impurities concentration characteristics in the fuel as a function of the fouling thickness in the partition of the filter is performed. The development of impurities was divided into three stages. In the article for one case the trend line was presented. The article was completed conclusions.

Effect of corona discharge treatment on indigo dyed cotton fabric

2008 ◽  
Vol 124 (1) ◽  
pp. 43-47 ◽  
Author(s):  
Shirin Nourbakhsh ◽  
Mohammad Esmail Yazdanshenas
Keyword(s):  
Corona Discharge ◽  
Cotton Fabric ◽  
Discharge Treatment
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