Characterization of Booming Sands

2002 ◽  
Vol 759 ◽  
Author(s):  
Katherine S. Brantley ◽  
Melany L. Hunt ◽  
Christopher E. Brennen ◽  
Steven S. Gao
Keyword(s):  
United States ◽  
Moisture Content ◽  
Size Distribution ◽  
Sand Dunes ◽  
The United States ◽  
Size Distributions ◽  
Narrow Size Distribution ◽  
Dune Sands ◽  
The Mean

ABSTRACTMany sand dunes – at least seven in the United States – make loud booming noises when they avalanche. Records of the sound are centuries old, but the cause remains a mystery. This study examines properties of both the sand and the sound.Properties of the sand reveal clues about the source of the booming. Sand must be extremely dry to boom, but low moisture content alone is not sufficient to facilitate booming. Although the mean grain diameters of both booming and silent dune sands range from 0.20 – 0.40mm, the booming samples have smaller standard deviations. However, synthetic sands with similar size distributions do not boom, so a narrow size distribution cannot be solely responsible for the booming. Studies of the roundness and sphericity of the grains are currently underway.Air microphone and geophone recordings of the booming indicate that the fundamental frequency varies between 80–105 Hz depending on the dunes. This is consistent with previous measurements. Laboratory recordings of the “burping” sound that booming sand makes when shaken in a jar reveal a broad peak between 150–300 Hz.

scholarly journals Particle size distributions from laboratory-scale biomass fires using fast response instruments

2010 ◽  
Vol 10 (16) ◽  
pp. 8065-8076 ◽  
Author(s):  
S. Hosseini ◽  
Q. Li ◽  
D. Cocker ◽  
D. Weise ◽  
A. Miller ◽  
...  
Keyword(s):  
United States ◽  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Geometric Mean ◽  
The United States ◽  
Biomass Combustion ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Mean Diameter

Abstract. Particle size distribution from biomass combustion is an important parameter as it affects air quality, climate modelling and health effects. To date, particle size distributions reported from prior studies vary not only due to difference in fuels but also difference in experimental conditions. This study aims to report characteristics of particle size distributions in well controlled repeatable lab scale biomass fires for southwestern United States fuels with focus on chaparral. The combustion laboratory at the United States Department of Agriculture-Forest Service's Fire Science Laboratory (USDA-FSL), Missoula, MT provided a repeatable combustion and dilution environment ideal for measurements. For a variety of fuels tested the major mode of particle size distribution was in the range of 29 to 52 nm, which is attributable to dilution of the fresh smoke. Comparing mass size distribution from FMPS and APS measurement 51–68% of particle mass was attributable to the particles ranging from 0.5 to 10 μm for PM10. Geometric mean diameter rapidly increased during flaming and gradually decreased during mixed and smoldering phase combustion. Most fuels produced a unimodal distribution during flaming phase and strong biomodal distribution during smoldering phase. The mode of combustion (flaming, mixed and smoldering) could be better distinguished using the slopes in MCE (Modified Combustion Efficiency) vs. geometric mean diameter than only using MCE values.

Narrowing sputtered nanoparticle size distributions

1993 ◽  
Vol 8 (5) ◽  
pp. 995-1000 ◽  
Author(s):  
F.H. Kaatz ◽  
G.M. Chow ◽  
A.S. Edelstein
Keyword(s):  
Size Distribution ◽  
Mean Free Path ◽  
Particle Formation ◽  
Distribution Functions ◽  
Size Distributions ◽  
Narrow Size Distribution ◽  
Linear Arrangement ◽  
Nanocrystalline Particle ◽  
The Mean ◽  
Potential Use

By adjusting the sputtering rate and gas pressure, it is possible to form nanoparticles of different sizes, phases, and materials. We have investigated the spatial distribution of sputtered particle formation using a vertical, linear arrangement of substrates. Collecting the particles soon after they are formed, before they have time to grow and agglomerate, allows one to obtain a narrow size distribution. In the case of molybdenum, a narrow distribution of cubic particles is formed at relatively large distances (8 cm) from the source. These cubic particles collide and self-assemble in the vapor into arrays of larger cubic particles. The particle size histograms are fitted to lognormal distribution functions. How supersaturation occurs is discussed qualitatively as a function of the distance from the substrate, sputtering rate, and the mean free path in the vapor. This method of nanocrystalline particle formation has potential use in magnetic and opto-electronic (quantum dot) applications, where a narrow size distribution is required.

scholarly journals Impact of Advanced Fuel Cycles on Uncertainty Associated With Geologic Repositories

2013 ◽  
Author(s):  
Rob P. Rechard ◽  
Joon Lee ◽  
Mark Sutton ◽  
Harris R. Greenberg ◽  
Bruce A. Robinson ◽  
...  
Keyword(s):  
United States ◽  
Qualitative Evaluation ◽  
The United States ◽  
Regulatory Environment ◽  
Fuel Cycles ◽  
Geologic Disposal ◽  
Advanced Fuel ◽  
The Mean ◽  
The Impact

This paper provides a qualitative evaluation of the impact of advanced fuel cycles, particularly partition and transmutation of actinides, on the uncertainty associated with geologic disposal. Based on the discussion, advanced fuel cycles, will not materially alter (1) the repository performance, (2) the spread in dose results around the mean, (3) the modeling effort to include significant features, events, and processes in the performance assessment, or (4) the characterization of uncertainty associated with a geologic disposal system in the regulatory environment of the United States.

scholarly journals American Farms Keep Growing: Size, Productivity, and Policy

2014 ◽  
Vol 28 (1) ◽  
pp. 147-166 ◽  
Author(s):  
Daniel A. Sumner
Keyword(s):  
United States ◽  
Size Distribution ◽  
Productivity Growth ◽  
The United States ◽  
Farm Size ◽  
Size Distributions ◽  
Commercial Agriculture ◽  
Subsidy Policy ◽  
Farm Productivity ◽  
Commercial Farms

Commercial agriculture in the United States is comprised of several hundred thousand farms, and these farms continue to become larger and fewer. The size of commercial farms is sometimes best-measured by sales, in other cases by acreage, and in still other cases by quantity produced of specific commodities, but for many commodities, size has doubled and doubled again in a generation. This article summarizes the economics of commercial agriculture in the United States, focusing on growth in farm size and other changes in size distribution in recent decades. I also consider the relationships between farm size distributions and farm productivity growth and farm subsidy policy.

scholarly journals Longer Residence in the United States is Associated With More Physical Function Limitations in African Immigrant Older Adults

2020 ◽  
pp. 073346482097760
Author(s):  
Manka Nkimbeng ◽  
Yvonne Commodore-Mensah ◽  
Jacqueline L. Angel ◽  
Karen Bandeen-Roche ◽  
Roland J. Thorpe ◽  
...  
Keyword(s):  
United States ◽  
Older Adults ◽  
Confidence Interval ◽  
Physical Function ◽  
Racial Discrimination ◽  
African Immigrants ◽  
The United States ◽  
African Immigrant ◽  
High Discrimination ◽  
The Mean

Acculturation and racial discrimination have been independently associated with physical function limitations in immigrant and United States (U.S.)-born populations. This study examined the relationships among acculturation, racial discrimination, and physical function limitations in N = 165 African immigrant older adults using multiple linear regression. The mean age was 62 years ( SD = 8 years), and 61% were female. Older adults who resided in the United States for 10 years or more had more physical function limitations compared with those who resided here for less than 10 years ( b = −2.62, 95% confidence interval [CI] = [–5.01, –0.23]). Compared to lower discrimination, those with high discrimination had more physical function limitations ( b = −2.51, 95% CI = [–4.91, –0.17]), but this was no longer significant after controlling for length of residence and acculturation strategy. Residing in the United States for more than 10 years is associated with poorer physical function. Longitudinal studies with large, diverse samples of African immigrants are needed to confirm these associations.

scholarly journals A Retrospective Analysis of Softball-Related Head and Facial Injuries Treated in United States Emergency Departments, 2013-2017

2019 ◽  
Vol 7 (2) ◽  
pp. 232596711982566 ◽  
Author(s):  
John S. Strickland ◽  
Marie Crandall ◽  
Grant R. Bevill
Keyword(s):  
United States ◽  
Head Injuries ◽  
The United States ◽  
Weighted Estimate ◽  
Body Parts ◽  
Facial Injuries ◽  
Closed Head Injuries ◽  
Closed Head ◽  
The Mean ◽  
Race Ethnicity

Background: Softball is a popular sport played through both competitive and recreational leagues. While head and facial injuries are a known problem occurring from games, little is known about the frequency or mechanisms by which they occur. Purpose: To analyze head/face injury diagnoses and to identify the mechanisms associated with such injuries. Study Design: Descriptive epidemiological study. Methods: A public database was used to query data related to head/facial injuries sustained in softball. Data including age, sex, race/ethnicity, injury diagnosis, affected body parts, disposition, incident location, and narrative descriptions were collected and analyzed. Results: A total of 3324 head and face injuries were documented in the database over the time span of 2013 to 2017, resulting in a nationwide weighted estimate of 121,802 head/face injuries occurring annually. The mean age of the players was 21.5 ± 14.4 years; 72.1% of injured players were female, while 27.9% were male. The most common injury diagnoses were closed head injuries (22.0%), contusions (18.7%), concussions (17.7%), lacerations (17.1%), and fractures (15.1%). The overwhelming majority of injuries involved being struck by a ball (74.3%), followed by colliding with another player (8.3%), colliding with the ground or a fixed object (5.0%), or being struck by a bat (2.8%). For those injuries caused by a struck-by-ball incident, most occurred from defensive play (83.7% were fielders struck by a hit or thrown ball) as opposed to offensive play (12.3% were players hit by a pitch or runners struck by a ball). Although helmet usage was poorly tracked in the database, female players (1.3%) were significantly more likely to have been wearing a helmet at the time of injury than were male players (0.2%) ( P = .002). Conclusion: The present study demonstrates that a large number of head and face injuries occur annually within the United States as a result of softball play. A variety of injuries were observed, with the majority involving defensive players being struck by the ball, which highlights the need for more focus on player safety by stronger adherence to protective headgear usage and player health monitoring.

Phylogenetic and phenotypic characterization of Fomes fasciatus and Fomes fomentarius in the United States

Mycologia ◽  
2013 ◽  
Vol 105 (6) ◽  
pp. 1524-1534 ◽  
Author(s):  
Meghan A. McCormick ◽  
Larry F. Grand ◽  
Justin B. Post ◽  
Marc A. Cubeta
Keyword(s):  
United States ◽  
The United States ◽  
Phenotypic Characterization ◽  
Fomes Fomentarius
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