scholarly journals COUNTERACTING HIGH WINDS WITH LOW PRESSURE: DEVELOPMENT AND TESTING OF A NEW ROOF VENT SYSTEM

2011 ◽  
Vol 6 (4) ◽  
pp. 65-76
Author(s):  
Elizabeth Grant ◽  
James Jones
Keyword(s):  
High Speed ◽  
Performance Test ◽  
Ambient Pressure ◽  
Low Pressure ◽  
High Wind ◽  
System Failures ◽  
Wind Speeds ◽  
Pressure Development ◽  
Wind Events ◽  
And Performance

Roof system failures are common during high wind events. In locations subject to high wind conditions, membrane roofing systems must typically be either physically attached or fully adhered to the substrate or ballast may be added to weigh down the membrane. An alternative to these installation approaches could be to use aerodynamics principles such as the Bernoulli and Venturi effects to create a low-pressure region beneath the membrane roof that is lower than the ambient pressure and thus counteracts the uplifting force. A new omnidirectional vent has been designed and tested that takes advantage of these aerodynamics principles to induce low pressure under the membrane layer. This new vent operates with no moving parts and was tested in the high-speed stability wind tunnel at Virginia Tech to wind speeds up to 233 km/h. The results demonstrate that this new vent generates pressures lower than the ambient when subjected to high wind conditions. This paper presents the design principles and performance test results for this new roof vent system and other applications for roof vent technologies.

Empirical Evidence of Long-Distance Dispersal in Miscanthus sinensis and Miscanthus × giganteus

2011 ◽  
Vol 4 (1) ◽  
pp. 142-150 ◽  
Author(s):  
Lauren D. Quinn ◽  
David P. Matlaga ◽  
J. Ryan Stewart ◽  
Adam S. Davis
Keyword(s):  
Miscanthus Sinensis ◽  
High Wind ◽  
Dispersal Patterns ◽  
Long Distance ◽  
Bioenergy Grasses ◽  
Wind Speeds ◽  
Miscanthus Giganteus ◽  
Prevailing Wind Direction ◽  
Wind Events ◽  
Dispersal Distances

AbstractMany perennial bioenergy grasses have the potential to escape cultivation and invade natural areas. We quantify dispersal, a key component in invasion, for two bioenergy candidates:Miscanthus sinensis and M. × giganteus. For each species, approximately 1 × 106 caryopses dispersed anemochorously from a point source into traps placed in annuli near the source (0.5 to 5 m; 1.6 to 16.4 ft) and in arcs (10 to 400 m) in the prevailing wind direction. For both species, most caryopses (95% for M. sinensis and 77% for M. × giganteus) were captured within 50 m of the source, but a small percentage (0.2 to 3%) were captured at 300 m and 400 m. Using a maximum-likelihood approach, we evaluated the degree of support in our empirical dispersal data for competing functions to describe seed-dispersal kernels. Fat-tailed functions (lognormal, Weibull, and gamma (Γ)) fit dispersal patterns best for both species overall, but because M. sinensis dispersal distances were significantly affected by wind speed, curves were also fit separately for dispersal distances in low, moderate, and high wind events. Wind speeds shifted the M. sinensis dispersal curve from a thin-tailed exponential function at low speeds to fat-tailed lognormal functions at moderate and high wind speeds. M. sinensis caryopses traveled farther in higher wind speeds (low, 30 m; moderate, 150 m; high, 400 m). Our results demonstrate the ability of Miscanthus caryopses to travel long distances and raise important implications for potential escape and invasion of fertile Miscanthus varieties from bioenergy cultivation.

On the Development and Performance Test of Combined Packing Integrated Device for Treating Domestic Sewage Aboard Ships

2011 ◽  
Vol 66-68 ◽  
pp. 2153-2157
Author(s):  
Zhi Li Chen ◽  
Kai Sheng Xiong ◽  
Wan Tu Zhang ◽  
Wen Biao Wang ◽  
Wen Ping Chen ◽  
...  
Keyword(s):  
High Speed ◽  
Performance Test ◽  
Simulation Experiment ◽  
Sewage Treatment ◽  
High Specific Surface Area ◽  
Domestic Sewage ◽  
Raw Water ◽  
And Performance ◽  
Integrated Device ◽  
The Impact

This paper elaborates on the development of elastic combined packing and an integrated device for treating domestic sewage aboard ships, analyzes the growth of combined packing microorganisms, the speed of membrane forming as well as the impact of raw water quality on membrane forming, and conducts a simulation experiment of treating domestic sewage by membrane bio-reactors. Researches show that elastic combined packing features high specific surface area and high speed of membrane forming and that this integrated domestic sewage treatment device performs well and can be widely applied.

scholarly journals First laboratory study of air–sea gas exchange at hurricane wind speeds

Ocean Science ◽  
2014 ◽  
Vol 10 (2) ◽  
pp. 257-265 ◽  
Author(s):  
K. E. Krall ◽  
B. Jähne
Keyword(s):  
Wave Breaking ◽  
High Speed ◽  
Wind Wave ◽  
Gas Transfer ◽  
High Wind ◽  
Transfer Velocity ◽  
Data Set ◽  
Wind Speeds ◽  
Bubble Cloud ◽  
Hurricane Wind

Abstract. In a pilot study conducted in October and November 2011, air–sea gas transfer velocities of the two sparingly soluble trace gases hexafluorobenzene and 1,4-difluorobenzene were measured in the unique high-speed wind-wave tank at Kyoto University, Japan. This air–sea interaction facility is capable of producing hurricane strength wind speeds of up to u10 =67 m s−1. This constitutes the first lab study of gas transfer at such high wind speeds. The measured transfer velocities k600 spanned two orders of magnitude, lying between 11 cm h−1 and 1180 cm h−1 with the latter being the highest ever measured wind-induced gas transfer velocity. The measured gas transfer velocities are in agreement with the only available data set at hurricane wind speeds (McNeil and D'Asaro, 2007). The disproportionately large increase of the transfer velocities found at highest wind speeds indicates a new regime of air–sea gas transfer, which is characterized by strong wave breaking, enhanced turbulence and bubble cloud entrainment.

scholarly journals Aggregated particles caused by instrument artifact

2018 ◽  
Vol 11 (4) ◽  
pp. 2225-2237
Author(s):  
Ashley M. Pierce ◽  
S. Marcela Loría-Salazar ◽  
W. Patrick Arnott ◽  
Grant C. Edwards ◽  
Matthieu B. Miller ◽  
...  
Keyword(s):  
Preliminary Analysis ◽  
Large Scale ◽  
Aerodynamic Diameter ◽  
Ambient Particulate Matter ◽  
High Wind ◽  
X Ray ◽  
Wind Speeds ◽  
Primary Particles ◽  
Wind Events ◽  
Pass Through

Abstract. Previous studies have indicated that superaggregates, clusters of aggregates of soot primary particles, can be formed in large-scale turbulent fires. Due to lower effective densities, higher porosity, and lower aerodynamic diameters, superaggregates may pass through inlets designed to remove particles < 2.5 µm in aerodynamic diameter (PM2.5). Ambient particulate matter samples were collected at Peavine Peak, NV, USA (2515 m) northwest of Reno, NV, USA from June to November 2014. The Teledyne Advanced Pollution Instrumentation (TAPI) 602 BetaPlus particulate monitor was used to collect PM2.5 on two filter types. During this time, aggregated particles > 2.5 µm in aerodynamic diameter were collected on 36 out of 158 sample days. On preliminary analysis, it was thought that these aggregated particles were superaggregates, depositing past PM10 (particles < 10 µm in aerodynamic diameter) pre-impactors and PM2.5 cyclones. However, further analysis revealed that these aggregated particles were dissimilar to superaggregates observed in previous studies, both in morphology and in elemental composition. To determine if the aggregated particles were superaggregates or an instrument artifact, samples were investigated for the presence of certain elements, the occurrence of fires, high relative humidity and wind speeds, as well as the use of generators on site. Samples with aggregated particles, referred to as aggregates, were analyzed using a scanning electron microscope for size and shape and energy dispersive X-ray spectroscopy was used for elemental analysis. It was determined, based on the high amounts of aluminum present in the aggregate samples, that a sampling artifact associated with the sample inlet and prolonged, high wind events was the probable reason for the observed aggregates.

scholarly journals Maximum Wind Gusts Associated with Human-Reported Nonconvective Wind Events and a Comparison to Current Warning Issuance Criteria

2016 ◽  
Vol 31 (2) ◽  
pp. 451-465 ◽  
Author(s):  
Paul W. Miller ◽  
Alan W. Black ◽  
Castle A. Williams ◽  
John A. Knox
Keyword(s):  
Threshold Level ◽  
Daily Maximum ◽  
Eastern United States ◽  
High Wind ◽  
Maximum Wind ◽  
Wind Speeds ◽  
Wind Gusts ◽  
Historical Climatology ◽  
Wind Potential ◽  
Wind Events

Abstract Nonconvective high winds are a deceptively hazardous meteorological phenomenon. Though the National Weather Service (NWS) possesses an array of products designed to alert the public to nonconvective wind potential, documentation justifying the choice of issuance thresholds is scarce. Measured wind speeds from the Global Historical Climatology Network (GHCN)-Daily dataset associated with human-reported nonconvective wind events from Storm Data are examined in order to assess the suitability of the current gust criteria for the NWS wind advisory and high wind warning. Nearly 92% (45%) of the nonconvective wind events considered from Storm Data were accompanied by peak gusts beneath the high wind warning (wind advisory) threshold of 58 mi h−1 (25.9 m s−1) [46 mi h−1 (20.6 m s−1)], and greater than 74% (28%) of all fatal and injury-causing events were associated with peak gusts below these same product gust criteria. NWS wind products were disproportionately issued in areas of complex terrain where wind climatologies include a greater frequency of high wind warning threshold-level gusts, irrespective of observed impacts. For many areas of the eastern United States, a 58 mi h−1 (25.9 m s−1) gust of convective, tropical, or nonconvective origin falls within the top 0.5% of all observed daily maximum wind gusts, nearly eliminating the possibility of a nonconvective gust meeting the issuance criterion.

scholarly journals Intense and Extreme Wind Speeds Observed by Anemometer and Seismic Networks: An Eastern U.S. Case Study

2014 ◽  
Vol 53 (11) ◽  
pp. 2417-2429 ◽  
Author(s):  
S. C. Pryor ◽  
R. Conrick ◽  
C. Miller ◽  
J. Tytell ◽  
R. J. Barthelmie
Keyword(s):  
United States ◽  
Wind Speed ◽  
Eastern United States ◽  
High Wind ◽  
Synoptic Scale ◽  
Near Surface ◽  
Wind Speeds ◽  
Extreme Wind ◽  
Wind Events ◽  
The Impact

AbstractThe scale and intensity of extreme wind events have tremendous relevance to determining the impact on infrastructure and natural and managed ecosystems. Analyses presented herein show the following. 1) Wind speeds in excess of the station-specific 95th percentile are coherent over distances of up to 1000 km over the eastern United States, which implies that the drivers of high wind speeds are manifest at the synoptic scale. 2) Although cold fronts associated with extratropical cyclones are a major cause of high–wind speed events, maximum sustained and gust wind speeds are only weakly dependent on the near-surface horizontal temperature gradient across the front. 3) Gust factors (GF) over the eastern United States have a mean value of 1.57 and conform to a lognormal probability distribution, and the relationship between maximum observed GF and sustained wind speed conforms to a power law with coefficients of 5.91 and −0.499. Even though there is coherence in the occurrence of intense wind speeds at the synoptic scale, the intensity and spatial extent of extreme wind events are not fully characterized even by the dense meteorological networks deployed by the National Weather Service. Seismic data from the USArray, a program within the Earthscope initiative, may be suitable for use in mapping high-wind and gust events, however. It is shown that the seismic channels exhibit well-defined spectral signatures under conditions of high wind, with a variance peak at frequencies of ~0.04 s−1 and an amplitude that appears to scale with the magnitude of observed wind gusts.

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