scholarly journals Preliminary Evaluation of Filtration Efficiency and Differential Pressure ASTM F3502 Testing Methods of Non-Medical Masks Using a Face Filtration Mount

2021 ◽  
Vol 18 (8) ◽  
pp. 4124
Author(s):  
Charles Freeman ◽  
Reuben Burch ◽  
Lesley Strawderman ◽  
Catherine Black ◽  
David Saucier ◽  
...  
Keyword(s):  
Filtration Efficiency ◽  
Preliminary Evaluation ◽  
Testing Methods ◽  
Airflow Resistance ◽  
Minimum Standards ◽  
New Methods ◽  
Evaluation Procedures ◽  
Upper Limits ◽  
Control And Prevention ◽  
The Mean

Research surrounding the mandated use of non-medical fabric masks is inconsistent and often confusing when compared to the standard N95. A recently published standard from ASTM International and the Centers for Disease Control and Prevention attempts to normalize evaluation procedures. The purpose of this study is to conduct a preliminary evaluation of the new methods for testing filtration efficiency of masks outlined by ASTM International F3502, where results can be directly compared to standards outlined for non-medical fabric masks. Eleven consumer non-medical fabric masks were tested for filtration efficiency and airflow resistance using a face filtration mount in accordance with the newly released ASTM International standard for facial barriers. The mean FE% (SD) ranged from 0.46% (0.44) to 11.80% (2.76) with the 3-layer athletic mesh having the highest performance and the highest deviations. All the masks tested following the procedure failed to meet to minimum FE of 20%; however all masks performed below the minimum upper limits for airflow resistance. Using a non-medical fabric masks as the sole mitigation strategy may not be as effective, as previously reported. With efforts to standardize and regulate the non-medical fabric mask market, this study demonstrates a variety of currently available consumer mask products do not meet the minimum standards nor are these remotely close to the standards of surgical or N95 masks.

scholarly journals Material Suitability Testing for Nonmedical Grade Community Face Masks to Decrease Viral Transmission During a Pandemic

2020 ◽  
pp. 1-7
Author(s):  
Csanad Varallyay ◽  
Ningcheng (Peter) Li ◽  
Brendan Case ◽  
Bryan Wolf
Keyword(s):  
Pressure Gauge ◽  
Filtration Efficiency ◽  
Viral Transmission ◽  
Airflow Resistance ◽  
Nonwoven Fabrics ◽  
Filtration Performance ◽  
Surgical Masks ◽  
Fit Testing ◽  
Control And Prevention ◽  
Fabric Material

Abstract Objectives: Cloth face covering has been recommended by the Centers for Disease Control and Prevention to decrease community viral transmission. This study aims to determine the filtration efficiency and airflow resistance of common household materials available for homemade mask production by comparing numbers of fabrics, various layers, and manipulation. Methods: Common household woven, knitted, and nonwoven fabrics were tested for filtration efficiency using a fit testing setup and airflow resistance with pressure gauge setup. Three different levels of layering (1, 2, and 4) were tested. Some fabric material was further tested after washing and drying. Filtration performance, the area under the fitted curve comparing airflow resistance and filtration efficiency, was calculated for each fabric material and compared. Results: Layering increased filtration efficiency and airflow resistance (P < 0.0001 and P < 0.01, respectively). Polyester felt demonstrated the highest filtration performance index (P < 0.0001), higher than all tested 100% cotton materials (all P < 0.05) as well as surgical masks (P < 0.05). Washing plus drying did not alter filtration performance significantly (P > 0.05). Conclusions: A filtration performance of common household fabrics were compared. Homemade mask designers and producers will have improved data to better balance effectiveness, availability, and comfort with the goal of decreasing community viral transmission.

Analysis and Improvement of Random Number Generating Algorithm

2010 ◽  
Vol 34-35 ◽  
pp. 153-156
Author(s):  
Yong Fei Li ◽  
Qiao Fang Zhao
Keyword(s):  
Random Number ◽  
Computer Application ◽  
Random Testing ◽  
Testing Methods ◽  
Mathematical Algorithm ◽  
New Methods ◽  
Pseudo Random Number ◽  
Traditional Algorithm

Random number is widely used in computer application. What is used commonly in practice is pseudo-random number generated by mathematical algorithm. Several useful pseudo-random number generating algorithm and random testing methods are discussed. And according to the disadvantage of traditional algorithm, improvement of pseudo-random number generating algorithm and some new methods to generate real-random number are summarized and analyzed.

Mapping of Health Technology Assessment in China: Situation Analysis and International Comparison

2019 ◽  
Vol 35 (5) ◽  
pp. 401-407 ◽  
Author(s):  
Yingyao Chen ◽  
Xunyouzhi Chi ◽  
Yao He ◽  
Yan Wei ◽  
Wija Oortwijn ◽  
...  
Keyword(s):  
Nationwide Survey ◽  
Health Technology ◽  
Developed Countries ◽  
Health Provider ◽  
Situation Analysis ◽  
Mapping Study ◽  
Policy Makers ◽  
Control And Prevention ◽  
The Mean ◽  
Validated Instrument

AbstractObjectivesTo analyze the current development of HTA in China and to identify areas for improvement, we mapped the level of HTA development in China and compared it with the level of HTA development in ten other countries using a survey instrument.MethodsWe launched a nationwide survey targeting different stakeholders. For this purpose, we used a validated instrument that enables mapping HTA development in a country using eight domains. The views of the respondents regarding the overall level of HTA development and for each domain were compared with the results of a mapping study that included ten countries.ResultsIn total, we received 222 responses, 33 from policy-makers, 158 from researchers, and 31 from industry, as well as health provider representatives including 8 from hospitals, centers for disease control and prevention. We calculated the mean score for the level of HTA development. The overall HTA development for China was scored at 76.4 (out of a maximum of 146). Although the total score for China was comparable to the mean score of 75.6 among the ten countries, China scored significantly lower than the mean score of 117.0 among the three developed countries. In addition, China scored significantly lower in the domain of institutionalization compared to the other ten countries.ConclusionsChina needs to tackle the issue of low HTA institutionalization to strengthen the foundation of HTA development. Future government initiatives that institutionalize HTA, for example, establishing a national HTA system or consortium, will improve the development of HTA in China.

scholarly journals Preliminary evaluation of the VIsion PERformance (VIPER) simulator

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Denise S. Ryan ◽  
Rose K. Sia ◽  
Jennifer B. Eaddy ◽  
Lorie A. Logan ◽  
Jide O. Familoni ◽  
...  
Keyword(s):  
Visual Assessment ◽  
Identification Accuracy ◽  
Visual Performance ◽  
Preliminary Evaluation ◽  
Detection Distance ◽  
Sensitivity Testing ◽  
Road Signs ◽  
The Mean ◽  
Improvised Explosive ◽  
Explosive Devices

Abstract Background This study evaluated the VIsion PERformance (VIPER) simulator’s ability to assess the functional visual performance in warfighters conducting civilian and military tasks. Methods Thirty service members, aged 25–35 years old with a best corrected distance visual acuity (VA) better than or equal to 20/20 or logarithm of the minimum angle of resolution (logMAR) 0.00, were randomized to locate and identify road signs and mock improvised explosive devices (IEDs) under either daytime conditions or with infrared imagery, with (cc) and without (sc) wearing their habitual correction. Participants also underwent binocular uncorrected (UDVA) and corrected (CDVA) visual assessment, refraction, contrast sensitivity testing and wavefront aberrometry. Results The mean age was 28.47 years. The manifest spherical equivalent was − 3.16 ± 1.75 diopters (D), the UDVA in both eyes (OU) was logMAR 0.83 ± 0.47, and the CDVA OU was − 0.11 ± 0.06. For VIPER, the mean difference in the detection distance (DD) for road signs ccDD vs. scDD was 76.7 ± 52.8 m (P < 0.001). The average difference in identification distance (ID) ccID vs. scID was 13.9 ± 6.3 m (P < 0.001). The mean accuracies were 83.5 and 27.9% for cc and sc, respectively (P < 0.001). The regression analysis indicated that a 1.6 m change in the distance accounts for a 1% change in the accuracy (P = 0.002). Without correction, a 4.1 m change accounts for a 1% change in the accuracy (P < 0.001). The average IED ccDD was 29.9 ± 8.2 m, and that for scDD was 13.2 ± 13.6 m (P < 0.001). The average IED ccID was 32.2 ± 6.2 m and that for the scID was 7.4 ± 10.3 m (P < 0.001). The mean IED identification accuracy was 46.7 and 11.4% for cc and sc, respectively (P < 0.001). Conclusions The preliminary results reflect VIPER’s ability to assess functional visual performance when detecting and identifying signs and IEDs. Furthermore, VIPER is able to detect performance changes with and without correction.

Interaction of Creep and High Cycle Fatigue of IN 713LC Superalloy

2016 ◽  
Vol 258 ◽  
pp. 595-598 ◽  
Author(s):  
Vít Horník ◽  
Miroslav Šmíd ◽  
Pavel Hutař ◽  
Ludvík Kunz ◽  
Karel Hrbáček
Keyword(s):  
High Cycle Fatigue ◽  
Fatigue Tests ◽  
Preliminary Evaluation ◽  
Cycle Fatigue ◽  
Polycrystalline Nickel ◽  
Nickel Based Superalloy ◽  
Wide Range ◽  
The Mean ◽  
Mean Stresses ◽  
Superimposed Vibrations

The study deals with the interaction of creep and high cycle fatigue of cast polycrystalline nickel-based superalloy IN 713LC at high temperatures. Previous works indicated that creep lifetime of superalloy structures was un-affected or even slightly increased in the cases with superimposed vibrations. The reason for this behaviour was not well described up to now. Therefore, set of fatigue tests was conducted at high mean stresses level to observe this phenomenon. The mean stress was kept constant while the stress amplitudes were selected in order to measure wide range of conditions from pure creep to pure fatigue. Fractographic analysis by scanning electron microscopy (SEM) was done with the aim to identify governing damage mechanisms for particular test conditions as a preliminary evaluation of conducted tests.

Configuration and Evaluation of the WRF Model for the Study of Hawaiian Regional Climate

2012 ◽  
Vol 140 (10) ◽  
pp. 3259-3277 ◽  
Author(s):  
Chunxi Zhang ◽  
Yuqing Wang ◽  
Axel Lauer ◽  
Kevin Hamilton
Keyword(s):  
Land Surface ◽  
Climate Model ◽  
Dynamical Downscaling ◽  
Model Simulation ◽  
Regional Climate ◽  
Hawaiian Islands ◽  
Wrf Model ◽  
Trade Wind ◽  
Preliminary Evaluation ◽  
The Mean

Abstract The Weather Research and Forecasting (WRF) model V3.3 has been configured for the Hawaiian Islands as a regional climate model for the region (HRCM). This paper documents the model configuration and presents a preliminary evaluation based on a continuous 1-yr simulation forced by observed boundary conditions with 3-km horizontal grid spacing in the inner nested domain. The simulated vertical structure of the temperature and humidity are compared with twice-daily radiosonde observations at two stations. Generally the trade wind inversion (TWI) height and occurrence days are well represented. The simulation over the islands is compared with observations from nine surface climatological stations and a dense network of precipitation stations. The model simulation has generally small biases in the simulated surface temperature, relative humidity, and wind speed. The model realistically simulated the magnitude and geographical distribution of the mean rainfall over the Hawaiian Islands. In addition, the model simulation reproduced reasonably well the individual heavy rainfall events as seen from the time series of pentad mean rainfall averaged over island scales. Also the model reproduced the geographical variation of the mean diurnal rainfall cycle even though the observed diurnal cycle displays quite different features over different islands. Comparison with results obtained using the land surface dataset from the official release of the WRF model confirmed that the newly implemented land surface dataset generally improved the simulation of surface variables. These results demonstrate that the WRF can be a useful tool for dynamical downscaling of regional climate over the Hawaiian Islands.

scholarly journals The Refraction Correction of Elevation Angle for the Mean Annual Global Reference Atmosphere

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Leke Lin ◽  
Xiangming Chen ◽  
Ranran Hu ◽  
Zhenwei Zhao
Keyword(s):  
Elevation Angle ◽  
Space Station ◽  
Geosynchronous Orbit ◽  
Atmospheric Refraction ◽  
International Telecommunication Union ◽  
International Telecommunication ◽  
New Methods ◽  
Satellite Broadcasting ◽  
The Mean ◽  
Reference Atmosphere

In some frequency-sharing studies between fixed service and space radiocommunication services, including fixed-satellite, broadcasting-satellite, and space science services, it is necessary to estimate the apparent elevation angle of a space station, taking into account the atmospheric refraction. Recommendations ITU-R (International Telecommunication Union—Radiocommunication) P.834-9 and F.1333-1 detail similar methods regarding calculating the refraction correction for the elevation angle of the mean annual global reference atmosphere. Herein, both methods are approximated using the bending angle from the ground to the infinity height; this approach is most suitable for geosynchronous orbit satellites. In this paper, new methods for calculating the refraction correction for the elevation angle are proposed regarding the mean annual global reference atmosphere given in Recommendation ITU-R P.835-6. Specifically, the results of the ray-tracing method are fitted. The height of the new formulae is 100 km above sea level. For higher altitudes, correction methods are given based on free-space propagation. The proposed methods can be applied to the calculation of the refraction correction for the elevation of the mean annual global reference atmosphere for satellites at different orbital heights. Furthermore, these new methods compare favourably to the two ITU-R Recommendations.

Besoins en phosphore des bactéries métabolisant les hydrocarbures en mer

1976 ◽  
Vol 22 (9) ◽  
pp. 1364-1373 ◽  
Author(s):  
J. Le Petit ◽  
M.-H. N'Guyen
Keyword(s):  
Ionic Strength ◽  
Bacterial Growth ◽  
Bacterial Development ◽  
Biological Purification ◽  
Upper Limits ◽  
The Mean ◽  
Stimulation Of

The artificial stimulation of biological purification of sea-pollutant hydrocarbons requires phosphorus supply. The concentrations, corresponding to the optimal bacterial growth, depend, in particular, on ionic strength. They range between 2 and 8 × 10−4 M for waters in which the salinity is close to the mean salinity of an oceanic environment and between 1.5 and 3 × 10−3 M when these waters receive a significant supply of freshwater or when salinity is naturally weak. Inhibition of bacterial development has been observed either with a microflora, or with pure strains for concentrations higher than the upper limits of concentrations so defined.

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