Fog modelling during the ParisFog campaign: predictive approach and spatial heterogeneity effect

International Nuclear Information System (INIS)

Zhang, Xiaojing

2010-01-01

In fog or low clouds modeling, the accurate comprehension of the interaction among the turbulence, the microphysics and the radiation is still an important issue in improvement of numerical prediction quality. The improvement of fog modeling is important both in forecasting in transportation and in industrial domain by reason of their discharges atmospheric (cooling tower, smog...). The 1D version of Code-Saturne has been used for the numerical simulation with the observational data from the ParisFog campaign, which took place at the SIRTA site during 2006-2007 winter. The comparison between the simulation and observation shows that the model is able to reproduce correctly the fog evolution from its formation to its dissipation. The sensitivity analysis of the behavior of the different parameterizations shows that the fog dynamic is sensible to the turbulence closure, the fog water content to the sedimentation processes and the fog droplet spectrum to the nucleation scheme. The performance of a long-period simulation in forecasting mode shows that the robustness of the model and the contribution of the coupling by nudging and a mesoscale model in 36 hours advance. The 3D version of Code-Saturne allows us to study the effect of spatial heterogeneity on the fog formation. Firstly, the simulations have been performed within a homogeneous horizontal domain with RANS mode. And then, the surface roughness in different type of surface and the building area will be taken into account. (author) [fr

Acute exposure to acid fog. Effects on mucociliary clearance

International Nuclear Information System (INIS)

Laube, B.L.; Bowes, S.M. III; Links, J.M.; Thomas, K.K.; Frank, R.

1993-01-01

Submicrometric sulfuric acid (H2SO4) aerosol can affect mucociliary clearance without eliciting irritative symptoms or changes in pulmonary function. The effect of larger fog droplets containing H2SO4 on mucociliary clearance is unknown. We quantified mucociliary clearance from the trachea (n = 4) and small airways (n = 7) of young healthy male adults after an acute exposure to H2SO4 fog (MMAD = 10.3 microns; pH = 2.0; liquid water content = 481 +/- 65 mg/m3; osmolarity = 30 mOsm). Acid fog (AF) or saline fog (SF) (10.9 microns; 492 +/- 116 mg/m3; 30 mOsm) was administered for 40 min of unencumbered breathing (no mouth-piece) at rest and for 20 min of exercise sufficient to produce oronasal breathing. Fog exposures were followed by a methacholine (MCh) challenge (a measure of airway reactivity) or inhalation of technetium-99M radioaerosol (MMAD = 3.4 microns) on 2 study days each. Changes in symptoms and forced ventilatory function were also assessed. Clearance was quantified from computer-assisted analyses of gamma camera images of the lower respiratory tract in terms of %removal/min of the radiolabel from the trachea 25 min after inhalation and from the outer zone of the right lung after 1.9 to 3 h. Symptoms, forced ventilatory function, and MCh response were unaffected by either fog. Tracheal clearance was more rapid in four of four subjects after AF (0.83 +/- 1.58% removal/min) compared with that after SF (-0.54 +/- 0.85% removal/min). Outer zone clearance was more rapid in six of seven subjects after AF (0.22 +/- 0.15% removal/min) compared with that after SF (0.01 +/- 0.09% removal/min)

Vegetation pattern formation in a fog-dependent ecosystem.

Science.gov (United States)

Borthagaray, Ana I; Fuentes, Miguel A; Marquet, Pablo A

2010-07-07

Vegetation pattern formation is a striking characteristic of several water-limited ecosystems around the world. Typically, they have been described on runoff-based ecosystems emphasizing local interactions between water, biomass interception, growth and dispersal. Here, we show that this situation is by no means general, as banded patterns in vegetation can emerge in areas without rainfall and in plants without functional root (the Bromeliad Tillandsia landbeckii) and where fog is the principal source of moisture. We show that a simple model based on the advection of fog-water by wind and its interception by the vegetation can reproduce banded patterns which agree with empirical patterns observed in the Coastal Atacama Desert. Our model predicts how the parameters may affect the conditions to form the banded pattern, showing a transition from a uniform vegetated state, at high water input or terrain slope to a desert state throughout intermediate banded states. Moreover, the model predicts that the pattern wavelength is a decreasing non-linear function of fog-water input and slope, and an increasing function of plant loss and fog-water flow speed. Finally, we show that the vegetation density is increased by the formation of the regular pattern compared to the density expected by the spatially homogeneous model emphasizing the importance of self-organization in arid ecosystems. (c) 2010 Elsevier Ltd. All rights reserved.

The Torbay fog facility

International Nuclear Information System (INIS)

Anon.

1998-01-01

A series of lighting sources are needed to help helicopters in their approaches to offshore oil platforms. The Torbay fog facility in Newfoundland was created in May 1998 and has been instrumental in studying different light sources. The facility has been used for fog characterization studies to determine the transmission of various light sources through fog up to a distance of 980 meters and correlating this with fog droplet size and concentration. The most cost effective method of increasing visibility is through high intensity searchlights. In this study, a 150 watt searchlight was set up on the south side of Torbay Bay and fog droplet size and concentration were measured. The main objective of the study was to characterize fog and precipitation (rain and snow) to enable daylight approaches to be made to the Hibernia platform in low visibility conditions. Different methods of measuring visibility were investigated to define a suitable sensor/detector which, when installed on the Hibernia platform, will allow a prediction of visibility to be made for flight operational purposes. 2 figs

Roles of Fog and Topography in Redwood Forest Hydrology

Science.gov (United States)

Francis, E. J.; Asner, G. P.

2017-12-01

Spatial variability of water in forests is a function of both climatic gradients that control water inputs and topo-edaphic variation that determines the flows of water belowground, as well as interactions of climate with topography. Coastal redwood forests are hydrologically unique because they are influenced by coastal low clouds, or fog, that is advected onto land by a strong coastal-to-inland temperature difference. Where fog intersects the land surface, annual water inputs from summer fog drip can be greater than that of winter rainfall. In this study, we take advantage of mapped spatial gradients in forest canopy water storage, topography, and fog cover in California to better understand the roles and interactions of fog and topography in the hydrology of redwood forests. We test a conceptual model of redwood forest hydrology with measurements of canopy water content derived from high-resolution airborne imaging spectroscopy, topographic variables derived from high-resolution LiDAR data, and fog cover maps derived from NASA MODIS data. Landscape-level results provide insight into hydrological processes within redwood forests, and cross-site analyses shed light on their generality.

Radiation in fog: quantification of the impact on fog liquid water based on ground-based remote sensing

Science.gov (United States)

Wærsted, Eivind G.; Haeffelin, Martial; Dupont, Jean-Charles; Delanoë, Julien; Dubuisson, Philippe

2017-09-01

Radiative cooling and heating impact the liquid water balance of fog and therefore play an important role in determining their persistence or dissipation. We demonstrate that a quantitative analysis of the radiation-driven condensation and evaporation is possible in real time using ground-based remote sensing observations (cloud radar, ceilometer, microwave radiometer). Seven continental fog events in midlatitude winter are studied, and the radiative processes are further explored through sensitivity studies. The longwave (LW) radiative cooling of the fog is able to produce 40-70 g m-2 h-1 of liquid water by condensation when the fog liquid water path exceeds 30 g m-2 and there are no clouds above the fog, which corresponds to renewing the fog water in 0.5-2 h. The variability is related to fog temperature and atmospheric humidity, with warmer fog below a drier atmosphere producing more liquid water. The appearance of a cloud layer above the fog strongly reduces the LW cooling relative to a situation with no cloud above; the effect is strongest for a low cloud, when the reduction can reach 100 %. Consequently, the appearance of clouds above will perturb the liquid water balance in the fog and may therefore induce fog dissipation. Shortwave (SW) radiative heating by absorption by fog droplets is smaller than the LW cooling, but it can contribute significantly, inducing 10-15 g m-2 h-1 of evaporation in thick fog at (winter) midday. The absorption of SW radiation by unactivated aerosols inside the fog is likely less than 30 % of the SW absorption by the water droplets, in most cases. However, the aerosols may contribute more significantly if the air mass contains a high concentration of absorbing aerosols. The absorbed radiation at the surface can reach 40-120 W m-2 during the daytime depending on the fog thickness. As in situ measurements indicate that 20-40 % of this energy is transferred to the fog as sensible heat, this surface absorption can contribute

Aerosol Particle Processing and Removal by Fogs: Observations in Chemically Heterogeneous Central California Radiation Fogs

International Nuclear Information System (INIS)

Collett, Jeffrey L.; Sherman, D. Eli; Moore, Katharine F.; Hannigan, Michael P.; Lee, Taehyoung

2001-01-01

Fog composition and deposition fluxes of fog water and fog solutes were measured in six radiation fog events in San Joaquin Valley, California during winter 1998/1999. Measurements made at 2 hr intervals with 0.30 m 2 and 0.06 m 2 Teflondeposition plates yielded excellent reproducibility(relative standard deviations of 3.8-6.0%) for water, nitrate, sulfate and ammonium. Water fluxes measured at 5 min intervals with a recording balance agreed well with the deposition plate measurements before 8:00 AM. After 8:00 AMevaporation proved problematic. The average deposition velocity from the study for fog nitrate(3.8 cm s -1 ) was less than those for fogsulfate (5.1 cm s -1 ) and ammonium (6.7 cms -1 ). All three species generally exhibited smaller deposition velocities than fog water. The species dependent trend in deposition velocities was consistent with preferential enrichment of these species in small fog drops (nitrate > sulfate> ammonium)

Safe lifting in patients with chronic low back pain : Comparing FCE lifting task and NIOSH lifting guideline

NARCIS (Netherlands)

Kuijer, Wietske; Dijkstra, Pieter U.; Brouwer, Sandra; Reneman, Michiel F.; Groothoff, Johan W.; Geertzen, Jan H. B.

2006-01-01

Introduction: Both the floor-to-waist lifting task of the Isernhagen Work Systems Functional Capacity Evaluation (IWS FCE) and recommended weight limit (RWL) of the NIOSH produce safe lifting weights and are used world-wide nowadays. It is unknown whether they produce similar safe lifting weights.

The narrow-leaf syndrome: a functional and evolutionary approach to the form of fog-harvesting rosette plants.

Science.gov (United States)

Martorell, Carlos; Ezcurra, Exequiel

2007-04-01

Plants that use fog as an important water-source frequently have a rosette growth habit. The performance of this morphology in relation to fog interception has not been studied. Some first-principles from physics predict that narrow leaves, together with other ancillary traits (large number and high flexibility of leaves, caudices, and/or epiphytism) which constitute the "narrow-leaf syndrome" should increase fog-interception efficiency. This was tested using aluminum models of rosettes that differed in leaf length, width and number and were exposed to artificial fog. The results were validated using seven species of Tillandsia and four species of xerophytic rosettes. The total amount of fog intercepted in rosette plants increased with total leaf area, while narrow leaves maximized interception efficiency (measured as interception per unit area). The number of leaves in the rosettes is physically constrained because wide-leafed plants can only have a few blades. At the limits of this constraint, net fog interception was independent of leaf form, but interception efficiency was maximized by large numbers of narrow leaves. Atmospheric Tillandsia species show the narrow-leaf syndrome. Their fog interception efficiencies were correlated to the ones predicted from aluminum-model data. In the larger xerophytic rosette species, the interception efficiency was greatest in plants showing the narrow-leaf syndrome. The adaptation to fog-harvesting in several narrow-leaved rosettes was tested for evolutionary convergence in 30 xerophytic rosette species using a comparative method. There was a significant evolutionary tendency towards the development of the narrow-leaf syndrome the closer the species grew to areas where fog is frequently available. This study establishes convergence in a very wide group of plants encompassing genera as contrasting as Tillandsia and Agave as a result of their dependence on fog.

Maximum acceptable weight of lift reflects peak lumbosacral extension moments in a functional capacity evaluation test using free style, stoop and squat lifting.

Science.gov (United States)

Kuijer, P P F M; van Oostrom, S H; Duijzer, K; van Dieën, J H

2012-01-01

It is unclear whether the maximum acceptable weight of lift (MAWL), a common psychophysical method, reflects joint kinetics when different lifting techniques are employed. In a within-participants study (n = 12), participants performed three lifting techniques--free style, stoop and squat lifting from knee to waist level--using the same dynamic functional capacity evaluation lifting test to assess MAWL and to calculate low back and knee kinetics. We assessed which knee and back kinetic parameters increased with the load mass lifted, and whether the magnitudes of the kinetic parameters were consistent across techniques when lifting MAWL. MAWL was significantly different between techniques (p = 0.03). The peak lumbosacral extension moment met both criteria: it had the highest association with the load masses lifted (r > 0.9) and was most consistent between the three techniques when lifting MAWL (ICC = 0.87). In conclusion, MAWL reflects the lumbosacral extension moment across free style, stoop and squat lifting in healthy young males, but the relation between the load mass lifted and lumbosacral extension moment is different between techniques. Tests of maximum acceptable weight of lift (MAWL) from knee to waist height are used to assess work capacity of individuals with low-back disorders. This article shows that the MAWL reflects the lumbosacral extension moment across free style, stoop and squat lifting in healthy young males, but the relation between the load mass lifted and lumbosacral extension moment is different between techniques. This suggests that standardisation of lifting technique used in tests of the MAWL would be indicated if the aim is to assess the capacity of the low back.

Fog water collection effectiveness: Mesh intercomparisons

Science.gov (United States)

Fernandez, Daniel; Torregrosa, Alicia; Weiss-Penzias, Peter; Zhang, Bong June; Sorensen, Deckard; Cohen, Robert; McKinley, Gareth; Kleingartner, Justin; Oliphant, Andrew; Bowman, Matthew

2018-01-01

To explore fog water harvesting potential in California, we conducted long-term measurements involving three types of mesh using standard fog collectors (SFC). Volumetric fog water measurements from SFCs and wind data were collected and recorded in 15-minute intervals over three summertime fog seasons (2014–2016) at four California sites. SFCs were deployed with: standard 1.00 m2 double-layer 35% shade coefficient Raschel; stainless steel mesh coated with the MIT-14 hydrophobic formulation; and FogHa-Tin, a German manufactured, 3-dimensional spacer fabric deployed in two orientations. Analysis of 3419 volumetric samples from all sites showed strong relationships between mesh efficiency and wind speed. Raschel mesh collected 160% more fog water than FogHa-Tin at wind speeds less than 1 m s–1 and 45% less for wind speeds greater than 5 m s–1. MIT-14 coated stainless-steel mesh collected more fog water than Raschel mesh at all wind speeds. At low wind speeds of wind speeds of 4–5 m s–1, it collected 41% more. FogHa-Tin collected 5% more fog water when the warp of the weave was oriented vertically, per manufacturer specification, than when the warp of the weave was oriented horizontally. Time series measurements of three distinct mesh across similar wind regimes revealed inconsistent lags in fog water collection and inconsistent performance. Since such differences occurred under similar wind-speed regimes, we conclude that other factors play important roles in mesh performance, including in-situ fog event and aerosol dynamics that affect droplet-size spectra and droplet-to-mesh surface interactions.

Fog water collection effectiveness: Mesh intercomparisons

Science.gov (United States)

Fernandez, Daniel; Torregrosa, Alicia; Weiss-Penzias, Peter; Zhang, Bong June; Sorensen, Deckard; Cohen, Robert; McKinley, Gareth; Kleingartner, Justin; Oliphant, Andrew; Bowman, Matthew

2018-01-01

To explore fog water harvesting potential in California, we conducted long-term measurements involving three types of mesh using standard fog collectors (SFC). Volumetric fog water measurements from SFCs and wind data were collected and recorded in 15-minute intervals over three summertime fog seasons (2014–2016) at four California sites. SFCs were deployed with: standard 1.00 m2 double-layer 35% shade coefficient Raschel; stainless steel mesh coated with the MIT-14 hydrophobic formulation; and FogHa-Tin, a German manufactured, 3-dimensional spacer fabric deployed in two orientations. Analysis of 3419 volumetric samples from all sites showed strong relationships between mesh efficiency and wind speed. Raschel mesh collected 160% more fog water than FogHa-Tin at wind speeds less than 1 m s–1 and 45% less for wind speeds greater than 5 m s–1. MIT-14 coated stainless-steel mesh collected more fog water than Raschel mesh at all wind speeds. At low wind speeds of steel mesh collected 3% more and at wind speeds of 4–5 m s–1, it collected 41% more. FogHa-Tin collected 5% more fog water when the warp of the weave was oriented vertically, per manufacturer specification, than when the warp of the weave was oriented horizontally. Time series measurements of three distinct mesh across similar wind regimes revealed inconsistent lags in fog water collection and inconsistent performance. Since such differences occurred under similar wind-speed regimes, we conclude that other factors play important roles in mesh performance, including in-situ fog event and aerosol dynamics that affect droplet-size spectra and droplet-to-mesh surface interactions.

Refreshing Music: Fog Harvesting with Harps

Science.gov (United States)

Shi, Weiwei; Anderson, Mark; Kennedy, Brook; Boreyko, Jonathan

2017-11-01

Fog harvesting is a useful technique for obtaining fresh water in arid climates. The wire meshes currently utilized for fog harvesting suffer from dual constraints: coarse meshes cannot efficiently capture fog, while fine meshes suffer from clogging issues. Here, we design a new type of fog harvester comprised of an array of vertical wires, which we call ``fog harps.'' To investigate the water collection efficiency, three fog harps were designed with different diameters (254 μm, 508 μm and 1.30 mm) but the same pitch-to-diameter ratio of 2. For comparison, three different size meshes were purchased with equivalent dimensions. As expected for the mesh structures, the mid-sized wires performed the best, with a drop-off in performance for the fine or coarse meshes. In contrast, the fog harvesting rate continually increased with decreasing wire diameter for the fog harps, due to its low hysteresis that prevented droplet clogging. This resulted in a 3-fold enhancement in the fog harvesting rate for the harp form factor compared to the mesh. The lack of a performance ceiling for the harps suggest that even greater enhancements could be achieved by scaling down to yet smaller sizes.

A hypersonic lift mechanism with decoupled lift and drag surfaces

Science.gov (United States)

Xu, YiZhe; Xu, ZhiQi; Li, ShaoGuang; Li, Juan; Bai, ChenYuan; Wu, ZiNiu

2013-05-01

In the present study, we propose a novel lift mechanism for which the lifting surface produces only lift. This is achieved by mounting a two-dimensional shock-shock interaction generator below the lifting surface. The shock-shock interaction theory in conjunction with a three dimensional correction and checked with computational fluid dynamics (CFD) is used to analyze the lift and drag forces as function of the geometrical parameters and inflow Mach number. Through this study, though limited to only inviscid flow, we conclude that it is possible to obtain a high lift to drag ratio by suitably arranging the shock interaction generator.

Fabrication of Biomimetic Fog-Collecting Superhydrophilic-Superhydrophobic Surface Micropatterns Using Femtosecond Lasers.

Science.gov (United States)

Kostal, Elisabeth; Stroj, Sandra; Kasemann, Stephan; Matylitsky, Victor; Domke, Matthias

2018-03-06

The exciting functionalities of natural superhydrophilic and superhydrophobic surfaces served as inspiration for a variety of biomimetic designs. In particular, the combination of both extreme wetting states to micropatterns opens up interesting applications, as the example of the fog-collecting Namib Desert beetle shows. In this paper, the beetle's elytra were mimicked by a novel three-step fabrication method to increase the fog-collection efficiency of glasses. In the first step, a double-hierarchical surface structure was generated on Pyrex wafers using femtosecond laser structuring, which amplified the intrinsic wetting property of the surface and made it superhydrophilic (water contact angle 150°). In the last step, the Teflon-like coating was selectively removed by fs-laser ablation to uncover superhydrophilic spots below the superhydrophobic surface, following the example of the Namib Desert beetle's fog-collecting elytra. To investigate the influence on the fog-collection behavior, (super)hydrophilic, (super)hydrophobic, and low and high contrast wetting patterns were fabricated on glass wafers using selected combinations of these three processing steps and were exposed to fog in an artificial nebulizer setup. This experiment revealed that high-contrast wetting patterns collected the highest amount of fog and enhanced the fog-collection efficiency by nearly 60% compared to pristine Pyrex glass. The comparison of the fog-collection behavior of the six samples showed that the superior fog-collection efficiency of surface patterns with extreme wetting contrast is due to the combination of water attraction and water repellency: the superhydrophilic spots act as drop accumulation areas, whereas the surrounding superhydrophobic areas allow a fast water transportation caused by gravity. The presented method enables a fast and flexible surface functionalization of a broad range of materials including transparent substrates, which offers exciting possibilities for

A method of detecting sea fogs using CALIOP data and its application to improve MODIS-based sea fog detection

International Nuclear Information System (INIS)

Wu, Dong; Lu, Bo; Zhang, Tianche; Yan, Fengqi

2015-01-01

A method to detect sea fogs from the measurement data acquired by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite is proposed in this paper. Because of the unique capability of vertical-resolved measurements, sea fogs and low clouds can be more easily distinguished in the CALIOP data compared with passive satellite measurements. Yellow Sea where sea fogs occur frequently is selected to test the method. Nine cases of daytime sea fog events from 2008 to 2011 in the Yellow Sea are studied intensively to characterize the remotely sensed radiation properties of various targets, such as clear-sky sea surface, sea fog, low cloud and high cloud. These fog cases are then used in an attempt to evaluate sea fogs identified from the MODIS measurements. The method proposed in this paper can also be used for nighttime cases. Multi-year sea fog dataset can be made from the CALIOP measurement and used to validate the MODIS sea fog detection. - Highlights: • A method of sea fog detection from the CALIOP measurements is proposed. • CALIOP VFM and 532-nm attenuated backscatter products are integrated used. • Sea fogs and low clouds can be more easily distinguished in the CALIOP data. • 9 Cases of daytime sea fog events in the Yellow Sea are selected to test the method. • The MODIS sea fog detections are evaluated using the collocated CALIOP data

C. elegans FOG-3/Tob can either promote or inhibit germline proliferation, depending on gene dosage and genetic context.

Science.gov (United States)

Snow, J J; Lee, M-H; Verheyden, J; Kroll-Conner, P L; Kimble, J

2013-05-23

Vertebrate Tob/BTG proteins inhibit cell proliferation when overexpressed in tissue-culture cells, and they can function as tumor suppressors in mice. The single Caenorhabditis elegans Tob/BTG ortholog, FOG-3, by contrast, was identified from its loss-of-function phenotype as a regulator of sperm fate specification. Here we report that FOG-3 also regulates proliferation in the germline tissue. We first demonstrate that FOG-3 is a positive regulator of germline proliferation. Thus, fog-3 null mutants possess fewer germ cells than normal, a modest but reproducible decrease observed for each of two distinct fog-3 null alleles. A similar decrease also occurred in fog-3/+ heterozygotes, again for both fog-3 alleles, revealing a haplo-insufficient effect on proliferation. Therefore, FOG-3 normally promotes proliferation, and two copies of the fog-3 gene are required for this function. We next overexpressed FOG-3 by removal of FBF, the collective term for FBF-1 and FBF-2, two nearly identical PUF RNA-binding proteins. We find that overexpressed FOG-3 blocks proliferation in fbf-1 fbf-2 mutants; whereas germ cells stop dividing and instead differentiate in fbf-1 fbf-2 double mutants, they continue to proliferate in fog-3; fbf-1 fbf-2 triple mutants. Therefore, like its vertebrate Tob/BTG cousins, overexpressed FOG-3 is 'antiproliferative'. Indeed, some fog-3; fbf-1 fbf-2 mutants possess small tumors, suggesting that FOG-3 can act as a tumor suppressor. Finally, we show that FOG-3 and FBF work together to promote tumor formation in animals carrying oncogenic Notch mutations. A similar effect was not observed when germline tumors were induced by manipulation of other regulators; therefore, this FOG-3 tumor-promoting effect is context dependent. We conclude that FOG-3 can either promote or inhibit proliferation in a manner that is sensitive to both genetic context and gene dosage. The discovery of these FOG-3 effects on proliferation has implications for our understanding of

A comparison of the performance of three types of passive fog gauges under conditions of wind-driven fog and precipitation

NARCIS (Netherlands)

Frumau, K.F.A.; Burkard, R.; Schmid, S.; Bruijnzeel, L.A.; Tobón, C.; Calvo-Alvado\\, J.C.

2011-01-01

Understanding of the 'typical' amounts of fog intercepted by different types of cloud forests is hampered by a lack of comparative information on local fog climatology. Usually some kind of 'fog gauge' is used to characterize fog occurrence and amounts. Moreover, wind-driven fog and precipitation

FOG-2 mediated recruitment of the NuRD complex regulates cardiomyocyte proliferation during heart development.

Science.gov (United States)

Garnatz, Audrey S; Gao, Zhiguang; Broman, Michael; Martens, Spencer; Earley, Judy U; Svensson, Eric C

2014-11-01

FOG-2 is a multi-zinc finger protein that binds the transcriptional activator GATA4 and modulates GATA4-mediated regulation of target genes during heart development. Our previous work has demonstrated that the Nucleosome Remodeling and Deacetylase (NuRD) complex physically interacts with FOG-2 and is necessary for FOG-2 mediated repression of GATA4 activity in vitro. However, the relevance of this interaction for FOG-2 function in vivo has remained unclear. In this report, we demonstrate the importance of FOG-2/NuRD interaction through the generation and characterization of mice homozygous for a mutation in FOG-2 that disrupts NuRD binding (FOG-2(R3K5A)). These mice exhibit a perinatal lethality and have multiple cardiac malformations, including ventricular and atrial septal defects and a thin ventricular myocardium. To investigate the etiology of the thin myocardium, we measured the rate of cardiomyocyte proliferation in wild-type and FOG-2(R3K5A) developing hearts. We found cardiomyocyte proliferation was reduced by 31±8% in FOG-2(R3K5A) mice. Gene expression analysis indicated that the cell cycle inhibitor Cdkn1a (p21(cip1)) is up-regulated 2.0±0.2-fold in FOG-2(R3K5A) hearts. In addition, we demonstrate that FOG-2 can directly repress the activity of the Cdkn1a gene promoter, suggesting a model by which FOG-2/NuRD promotes ventricular wall thickening by repression of this cell cycle inhibitor. Consistent with this notion, the genetic ablation of Cdkn1a in FOG-2(R3K5A) mice leads to an improvement in left ventricular function and a partial rescue of left ventricular wall thickness. Taken together, our results define a novel mechanism in which FOG-2/NuRD interaction is required for cardiomyocyte proliferation by directly down-regulating the cell cycle inhibitor Cdkn1a during heart development. Copyright © 2014 Elsevier Inc. All rights reserved.

Fog inerting criteria for hydrogen/air mixtures

International Nuclear Information System (INIS)

Tsai, S.S.; Liparulo, N.J.

1982-01-01

A distributed ignition system has been proposed to ignite hydrogen at low concentration in the ice condenser containment during severe accidents. The post-accident containment atmosphere could be misty due to fog generation from the break flow and condensation in the ice bed. Thus it is important to establish a fog inerting criterion for effective performance of the ignition system. This paper presents such a criterion that specifies the necessary fogging conditions, i.e., fog concentration and drop size, for inerting a hydrogen/air mixture. The criterion shows that the minimum fog inerting concentration varies with the square of the volume mean fog drop size. The present fog inerting criterion is shown to be in general agreement with the Factory Mutual test data

Cooling pond fog studies

International Nuclear Information System (INIS)

Hicks, B.B.

1978-01-01

The Fog Excess Water Index (FEWI) method of fog prediction has been verified by the use of data obtained at the Dresden cooling pond during 1976 and 1977 and by a reanalysis of observations made in conjunction with a study of cooling pond simulators during 1974. For applications in which the method is applied to measurements or estimates of bulk water temperature, a critical value of about 0.7 mb appears to be most appropriate. The present analyses confirm the earlier finding that wind speed plays little part in determining the susceptibility for fog generation

An assessment of acid fog

International Nuclear Information System (INIS)

Lipfert, F.W.

1992-01-01

Airborne particles have long been associated with adverse effects on public health, begin with the notorious air pollution disasters of several decades ago. Although H 2 SO 4 was identified early on as a potential causal factors during these episodes (in part because of concern for potential health effects of particle acidity per se has intensified only recently. Most of the recent aerometric research in the US on acid fog has focused on the ability of clouds and fog to deliver acidity to vegetation and ecosystems. Strong acids are characterized chemically by their pH or H + concentration. For fog, concentrations are referred to the droplet liquid content; for other (i.e., ''clear air'') aerosols, to the volume of air sampled. A useful measure of the relationship between aerosol and fog is obtained by comparing their mass concentrations on the basis of the same volume of air, by multiplying fogwater concentrations by liquid water content (LWC). This paper reviews fog measurement capability, physical properties and chemistry, and presents a simple urban airshed model which is used to simulate the evolution of fog and aerosol concentrations under urban stagnation conditions

An assessment of acid fog

Energy Technology Data Exchange (ETDEWEB)

Lipfert, F.W.

1992-12-31

Airborne particles have long been associated with adverse effects on public health, begin with the notorious air pollution disasters of several decades ago. Although H{sub 2}SO{sub 4} was identified early on as a potential causal factors during these episodes (in part because of concern for potential health effects of particle acidity per se has intensified only recently. Most of the recent aerometric research in the US on acid fog has focused on the ability of clouds and fog to deliver acidity to vegetation and ecosystems. Strong acids are characterized chemically by their pH or H{sup +} concentration. For fog, concentrations are referred to the droplet liquid content; for other (i.e., ``clear air``) aerosols, to the volume of air sampled. A useful measure of the relationship between aerosol and fog is obtained by comparing their mass concentrations on the basis of the same volume of air, by multiplying fogwater concentrations by liquid water content (LWC). This paper reviews fog measurement capability, physical properties and chemistry, and presents a simple urban airshed model which is used to simulate the evolution of fog and aerosol concentrations under urban stagnation conditions.

Functional Commutant Lifting and Interpolation on Generalized Analytic Polyhedra

Czech Academy of Sciences Publication Activity Database

Ambrozie, Calin-Grigore

2008-01-01

Roč. 34, č. 2 (2008), s. 519-543 ISSN 0362-1588 R&D Projects: GA ČR(CZ) GA201/06/0128 Institutional research plan: CEZ:AV0Z10190503 Keywords : intertwining lifting * interpolation * analytic functions Subject RIV: BA - General Mathematics Impact factor: 0.327, year: 2008

Combinatorial regulation of tissue specification by GATA and FOG factors

Science.gov (United States)

Chlon, Timothy M.; Crispino, John D.

2012-01-01

The development of complex organisms requires the formation of diverse cell types from common stem and progenitor cells. GATA family transcriptional regulators and their dedicated co-factors, termed Friend of GATA (FOG) proteins, control cell fate and differentiation in multiple tissue types from Drosophila to man. FOGs can both facilitate and antagonize GATA factor transcriptional regulation depending on the factor, cell, and even the specific gene target. In this review, we highlight recent studies that have elucidated mechanisms by which FOGs regulate GATA factor function and discuss how these factors use these diverse modes of gene regulation to control cell lineage specification throughout metazoans. PMID:23048181

fog-2 and the evolution of self-fertile hermaphroditism in Caenorhabditis.

Directory of Open Access Journals (Sweden)

Sudhir Nayak

2005-01-01

Full Text Available Somatic and germline sex determination pathways have diverged significantly in animals, making comparisons between taxa difficult. To overcome this difficulty, we compared the genes in the germline sex determination pathways of Caenorhabditis elegans and C. briggsae, two Caenorhabditis species with similar reproductive systems and sequenced genomes. We demonstrate that C. briggsae has orthologs of all known C. elegans sex determination genes with one exception: fog-2. Hermaphroditic nematodes are essentially females that produce sperm early in life, which they use for self fertilization. In C. elegans, this brief period of spermatogenesis requires FOG-2 and the RNA-binding protein GLD-1, which together repress translation of the tra-2 mRNA. FOG-2 is part of a large C. elegans FOG-2-related protein family defined by the presence of an F-box and Duf38/FOG-2 homogy domain. A fog-2-related gene family is also present in C. briggsae, however, the branch containing fog-2 appears to have arisen relatively recently in C. elegans, post-speciation. The C-terminus of FOG-2 is rapidly evolving, is required for GLD-1 interaction, and is likely critical for the role of FOG-2 in sex determination. In addition, C. briggsae gld-1 appears to play the opposite role in sex determination (promoting the female fate while maintaining conserved roles in meiotic progression during oogenesis. Our data indicate that the regulation of the hermaphrodite germline sex determination pathway at the level of FOG-2/GLD-1/tra-2 mRNA is fundamentally different between C. elegans and C. briggsae, providing functional evidence in support of the independent evolution of self-fertile hermaphroditism. We speculate on the convergent evolution of hermaphroditism in Caenorhabditis based on the plasticity of the C. elegans germline sex determination cascade, in which multiple mutant paths yield self fertility.

Fog deposition to the Atacama desert

Science.gov (United States)

Westbeld, A.; Klemm, O.; Griessbaum, F.; Sträter, E.; Larrain, H.; Osses, P.; Cereceda, P.

2010-07-01

In the Atacama Desert, one of the driest places on earth, fog deposition plays an important role for the water balance and for the survival of vulnerable ecosystems. The eddy covariance method, previously applied for the quantification of fog deposition to forests in various parts of the world, was used for the first time to measure deposition of fog water to a desert. We estimated the amount of water available for the ecosystem by deposition and determined the relevant processes driving fog deposition. This is especially important for the species Tillandsia landbecki living in coastal Atacama at the limit of plant existence with fog and dew being the only sources of liquid water. Between 31 July and 19 August, 2008, measurements were realized in a 31 ha large Tillandsia carpet at Cerro Guanaco, located 15 km south of Iquique, northern Chile. Several data quality assurance procedures were applied. For the values in compliance with the applied criteria, the mean total deposition per hour was determined (0.04 L per m2) for foggy periods. This number was applied to estimate the amount of water deposited during the measuring period, during the entire month of August 2008, and throughout a whole year. For August 2008, a frequency of fog of 16 %, as established during the measuring period, was assumed. The frequency for a whole year was estimated from the differences of the collected amount of water obtained with standard fog collectors installed at Cerro Guanaco in an earlier study. Calculations resulted in an amount of 2.5 L per m2 of deposited fog water for the measuring period. During the entire August, 4.4 L per m2 have likely been available, and for a whole year, a total of 25 L per m2 was estimated to have reached the surface. Inaccuracies could have been caused by the low amount of data applied, and by a possible underestimation of the deposition due to additional formation of radiation fog during the fog events. Three days were used for further analysis because

PERSPECTIVES FOR FOG COMPUTING IN MANUFACTURING

Directory of Open Access Journals (Sweden)

Jakub PIZOŃ

2016-09-01

Full Text Available This article discusses ongoing efforts to enable the fog computing vision in manufacturing. As a new paradigm of computing implementation of fog computing faces many challenges that open perspective of new applications within a field of manufacturing. It is expected that fog computing will be one of factors that will accelerate development of in forth industrial revolution. In this article we discuss the perspectives of manufacturing companies surrounded by new solutions of CPS, CPPS and CM in relation to fog computing.

33 CFR 118.130 - Fog signals.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Fog signals. 118.130 Section 118... LIGHTING AND OTHER SIGNALS § 118.130 Fog signals. On waterways where visibility is frequently reduced due to fog or other causes, the District Commander may require or authorize the installation of one or...

Coastal fog, climate change, and the environment

Science.gov (United States)

Torregrosa, Alicia; O'Brien, Travis A.; Faloona, Ian C.

2014-01-01

Coastal marine fog, a characteristic feature of climates generated at the eastern boundaries of ocean basins worldwide, evokes different feelings in those who experience it (see Figure 1). Authors and poets use fog to represent mystery, bleakness, and confusion. Film directors seek out fog to shroud scenes in eerie gloominess. Tourists visiting beaches bemoan the cool and damp conditions that create a striking contrast to the sunny warm conditions typically found less than a few kilometers inland. Airline passengers delayed by fog impatiently wait for the skies to clear. Residents get used to the Sun “rising” in midday after fog dissipates.

Remote sensing of height of a fog layer and temperature of fog droplets using infrared thermometer and meteorological satellite

International Nuclear Information System (INIS)

Inoue, K.; Abe, H.

1998-01-01

To study meteorological characteristics of cool foggy easterly (Yamase), by which rice production in the Tohoku region was frequently damaged, we measured temperature of the fog layer resulted from Yamase, using infrared thermal indicator and meteorological satellite (HIMAWARI). These temperature data were compared with wet-bulb and dry-bulb temperatures obtained by a ventilated psychrometer. Generally, the temperature of fog droplets estimated from infrared thermal indicator was higher than the wet-bulb temperature by about 0∼1°C. This result indicates clearly that fog droplets were cooled by evaporation on the droplet surface. Under the conditions that the fog layer is homogeneous in liquid water content and fog droplet size distribution, the height of the fog layer can be estimated by the observation of visibility and relative solar radiation flux. (author)

Urban-rural fog differences in Belgrade area, Serbia

Science.gov (United States)

Vujović, Dragana; Todorović, Nedeljko

2018-02-01

Urban/rural fog appearance during the last 27 years in the Belgrade region is analysed using hourly meteorological records from two meteorological stations: an urban station at Belgrade-Vračar (BV) and a rural station at Belgrade-Airport (BA). The effects of urban development on fog formation are discussed through analysis of fog frequency trends and comparison with a number of meteorological parameters. The mean annual and the mean annual minimum temperatures were greater at the urban BV station than at the rural BA station. The mean monthly relative humidity and the mean monthly water vapour pressure were greater at the rural than urban station. During the period of research (1988-2014), BA experiences 425 more days with fog than BV, which means that BV experiences fog for 62.68% of foggy days at BA. Trends in the number of days with fog were statistically non-significant. We analysed the fog occurrence during different types of weather. Fog in urban BV occurred more frequently during cyclonal circulation (in 52.75% of cases). In rural BA, the trend was the opposite and fog appeared more frequently during anticyclonic circulation (in 53.58% of cases). Fog at BV occurred most frequently in stable anticyclonic weather with light wind, when a temperature inversion existed (21.86% of cases). Most frequently, fog at BA occurred in the morning and only lasted a short time, followed by clearer skies during the anticyclonic warm and dry weather (22.55% of cases).

Friend of GATA (FOG) interacts with the nucleosome remodeling and deacetylase complex (NuRD) to support primitive erythropoiesis in Xenopus laevis.

Science.gov (United States)

Mimoto, Mizuho S; Christian, Jan L

2012-01-01

Friend of GATA (FOG) plays many diverse roles in adult and embryonic hematopoiesis, however the mechanisms by which it functions and the roles of potential interaction partners are not completely understood. Previous work has shown that overexpression of FOG in Xenopus laevis causes loss of blood suggesting that in contrast to its role in mammals, FOG might normally function to repress erythropoiesis in this species. Using loss-of-function analysis, we demonstrate that FOG is essential to support primitive red blood cell (RBC) development in Xenopus. Moreover, we show that it is specifically required to prevent excess apoptosis of circulating primitive RBCs and that in the absence of FOG, the pro-apoptotic gene Bim-1 is strongly upregulated. To identify domains of FOG that are essential for blood development and, conversely, to begin to understand the mechanism by which overexpressed FOG represses primitive erythropoiesis, we asked whether FOG mutants that are unable to interact with known co-factors retain their ability to rescue blood formation in FOG morphants and whether they repress erythropoiesis when overexpressed in wild type embryos. We find that interaction of FOG with the Nucleosome Remodeling and Deacetylase complex (NuRD), but not with C-terminal Binding Protein, is essential for normal primitive RBC development. In contrast, overexpression of all mutant and wild type constructs causes a comparable repression of primitive erythropoiesis. Together, our data suggest that a requirement for FOG and its interaction with NuRD during primitive erythropoiesis are conserved in Xenopus and that loss of blood upon FOG overexpression is due to a dominant-interfering effect.

Hematopoietic Overexpression of FOG1 Does Not Affect B-Cells but Reduces the Number of Circulating Eosinophils

Science.gov (United States)

Du Roure, Camille; Versavel, Aude; Doll, Thierry; Cao, Chun; Pillonel, Vincent; Matthias, Gabriele; Kaller, Markus; Spetz, Jean-François; Kopp, Patrick; Kohler, Hubertus; Müller, Matthias; Matthias, Patrick

2014-01-01

We have identified expression of the gene encoding the transcriptional coactivator FOG-1 (Friend of GATA-1; Zfpm1, Zinc finger protein multitype 1) in B lymphocytes. We found that FOG-1 expression is directly or indirectly dependent on the B cell-specific coactivator OBF-1 and that it is modulated during B cell development: expression is observed in early but not in late stages of B cell development. To directly test in vivo the role of FOG-1 in B lymphocytes, we developed a novel embryonic stem cell recombination system. For this, we combined homologous recombination with the FLP recombinase activity to rapidly generate embryonic stem cell lines carrying a Cre-inducible transgene at the Rosa26 locus. Using this system, we successfully generated transgenic mice where FOG-1 is conditionally overexpressed in mature B-cells or in the entire hematopoietic system. While overexpression of FOG-1 in B cells did not significantly affect B cell development or function, we found that enforced expression of FOG-1 throughout all hematopoietic lineages led to a reduction in the number of circulating eosinophils, confirming and extending to mammals the known function of FOG-1 in this lineage. PMID:24747299

[Multiple scattering of visible and infrared light by sea fog over wind driving rough sea surface].

Science.gov (United States)

Sun, Xian-Ming; Wang, Hai-Hua; Lei, Cheng-Xin; Shen, Jin

2013-08-01

The present paper is concerned with computing the multiple scattering characteristics of a sea fog-sea surface couple system within this context. The single scattering characteristics of sea fog were studied by Mie theory, and the multiple scattering of sunlight by single sea fog layer was studied by radiative transfer theory. The reflection function of a statistically rough ocean surface was obtained using the standard Kirchhoff formulation, with shadowing effects taken into account. The reflection properties of the combined sea fog and ocean surface were obtained employing the adding method, and the results indicated that the reflected light intensity of sea fog increased with the sea background.

About Security Solutions in Fog Computing

Directory of Open Access Journals (Sweden)

Eugen Petac

2016-01-01

Full Text Available The key for improving a system's performance, its security and reliability is to have the dataprocessed locally in remote data centers. Fog computing extends cloud computing through itsservices to devices and users at the edge of the network. Through this paper it is explored the fogcomputing environment. Security issues in this area are also described. Fog computing providesthe improved quality of services to the user by complementing shortages of cloud in IoT (Internet ofThings environment. Our proposal, named Adaptive Fog Computing Node Security Profile(AFCNSP, which is based security Linux solutions, will get an improved security of fog node withrich feature sets.

On the fog variability over south Asia

Energy Technology Data Exchange (ETDEWEB)

Syed, F.S. [Stockholm University, Department of Meteorology, Stockholm (Sweden); Pakistan Meteorological Department, Islamabad (Pakistan); Koernich, H.; Tjernstroem, M. [Stockholm University, Department of Meteorology, The Bert Bolin Centre for Climate Research, Stockholm (Sweden)

2012-12-15

An increasing trend in fog frequencies over south Asia during winter in the last few decades has resulted in large economical losses and has caused substantial difficulties in the daily lives of people. In order to better understand the fog phenomenon, we investigated the climatology, inter-annual variability and trends in the fog occurrence from 1976 to 2010 using observational data from 82 stations, well distributed over India and Pakistan. Fog blankets large area from Pakistan to Bangladesh across north India from west to east running almost parallel to south of the Himalayas. An EOF analysis revealed that the fog variability over the whole region is coupled and therefore must be governed by some large scale phenomenon on the inter-annual time scale. Significant positive trends were found in the fog frequency but this increase is not gradual, as with the humidity, but comprises of two distinct regimes shifts, in 1990 and 1998, with respect to both mean and variance. The fog is also detected in ERA-Interim 3 hourly, surface and model level forecast data when using the concept of ''cross-over temperature'' combined with boundary layer stability. This fog index is able to reproduce the regime shift around 1998 and shows that the method can be applied to analyze fog over south Asia. The inter-annual variability seems to be associated with the wave train originating from the North Atlantic in the upper troposphere that when causing higher pressure over the region results in an increased boundary layer stability and surface-near relative humidity. The trend and shifts in the fog occurrence seems to be associated with the gradual increasing trend in relative humidity from 1990 onwards. (orig.)

Fog-computing concept usage as means to enhance information and control system reliability

Science.gov (United States)

Melnik, E. V.; Klimenko, A. B.; Ivanov, D. Ya

2018-05-01

This paper focuses on the reliability issue of information and control systems (ICS). The authors propose using the elements of the fog-computing concept to enhance the reliability function. The key idea of fog-computing is to shift computations to the fog-layer of the network, and thus to decrease the workload of the communication environment and data processing components. As for ICS, workload also can be distributed among sensors, actuators and network infrastructure facilities near the sources of data. The authors simulated typical workload distribution situations for the “traditional” ICS architecture and for the one with fogcomputing concept elements usage. The paper contains some models, selected simulation results and conclusion about the prospects of the fog-computing as a means to enhance ICS reliability.

Friend of GATA (FOG interacts with the nucleosome remodeling and deacetylase complex (NuRD to support primitive erythropoiesis in Xenopus laevis.

Directory of Open Access Journals (Sweden)

Mizuho S Mimoto

Full Text Available Friend of GATA (FOG plays many diverse roles in adult and embryonic hematopoiesis, however the mechanisms by which it functions and the roles of potential interaction partners are not completely understood. Previous work has shown that overexpression of FOG in Xenopus laevis causes loss of blood suggesting that in contrast to its role in mammals, FOG might normally function to repress erythropoiesis in this species. Using loss-of-function analysis, we demonstrate that FOG is essential to support primitive red blood cell (RBC development in Xenopus. Moreover, we show that it is specifically required to prevent excess apoptosis of circulating primitive RBCs and that in the absence of FOG, the pro-apoptotic gene Bim-1 is strongly upregulated. To identify domains of FOG that are essential for blood development and, conversely, to begin to understand the mechanism by which overexpressed FOG represses primitive erythropoiesis, we asked whether FOG mutants that are unable to interact with known co-factors retain their ability to rescue blood formation in FOG morphants and whether they repress erythropoiesis when overexpressed in wild type embryos. We find that interaction of FOG with the Nucleosome Remodeling and Deacetylase complex (NuRD, but not with C-terminal Binding Protein, is essential for normal primitive RBC development. In contrast, overexpression of all mutant and wild type constructs causes a comparable repression of primitive erythropoiesis. Together, our data suggest that a requirement for FOG and its interaction with NuRD during primitive erythropoiesis are conserved in Xenopus and that loss of blood upon FOG overexpression is due to a dominant-interfering effect.

Organic matter in central California radiation fogs.

Science.gov (United States)

Herckes, Pierre; Lee, Taehyoung; Trenary, Laurie; Kang, Gongunn; Chang, Hui; Collett, Jeffrey L

2002-11-15

Organic matter was studied in radiation fogs in the San Joaquin Valley of California during the California Regional Particulate Air Quality Study (CRPAQS). Total organic carbon (TOC) concentrations ranged from 2 to 40 ppm of C. While most organic carbon was found in solution as dissolved organic carbon (DOC), 23% on average was not dissolved inside the fog drops. We observe a clear variation of organic matter concentration with droplet size. TOC concentrations in small fog drops (fogwater, consistent with the enrichment of the organic matter in smaller fog drops with lower terminal settling velocities.

Fog and soil weathering as sources of nutrients in a California redwood forest

Science.gov (United States)

Holly A. Ewing; Kathleen C. Weathers; Amanda M. Lindsey; Pamela H. Templer; Todd E. Dawson; Damon C. Bradbury; Mary K. Firestone; Vanessa K.S. Boukili

2012-01-01

Fog water deposition is thought to influence the ecological function of many coastal ecosystems, including coast redwood forests. We examined cation and anion inputs from fog and rain, as well as the fate of these inputs, within a Sonoma County, California, coast redwood forest to elucidate the availability of these ions and some of the biotic and abiotic processes...

Forecasting sea fog on the coast of southern China

Science.gov (United States)

Huang, H.; Huang, B.; Liu, C.; Tu, J.; Wen, G.; Mao, W.

2016-12-01

Forecast sea fog is still full of challenges. We have performed the numerical forecasting of sea fog on the coast of southern China by using the operational meso-scale regional model GRAPES (Global/Regional assimilation and prediction system). The GRAPES model horizontal resolution was 3km and with 66 vertical levels. A total of 72 hours forecasting of sea fog was conducted with hourly outputs over the sea fog event. The results show that the model system can predict reasonable characteristics of typical sea fog events on the coast of southern China. The scope of sea fog coincides with the observations of meteorological stations, the observations of the Marine Meteorological Science Experiment Base (MMSEB) at Bohe, Maoming and satellite products of sea fog. The goal of this study is to establish an operational numerical forecasting model system of sea fog on the coast of southern China.

Characterization of polycyclic aromatic hydrocarbons in fog-rain events.

Science.gov (United States)

Li, Xiang; Li, Pengfei; Yan, Lili; Chen, Jianmin; Cheng, Tiantao; Xu, Shifen

2011-11-01

Atmospheric polycyclic aromatic hydrocarbons (PAHs) mainly originate from incomplete combustion or pyrolysis of materials containing carbon and hydrogen. They exist in gas and particle phases, as well as dissolved or suspended in precipitation (fog or rain). Current studies in atmospheric PAHs are predominantly focused on fog and rainwater samples. Some sampling difficulties are associated with fog samples. This study presented the first observation of the characteristics of PAHs in fog samples using a solid phase microextraction (SPME) technique. Eighteen fog samples were collected during ten fog events from March to December 2009 in the Shanghai area. PAHs were extracted by SPME and analyzed by gas chromatography-mass spectrometry (GC-MS). As the compounds were partially soluble in water, with solubility decreasing with increasing molecular weight, low molecular weight (LMW) PAH compounds were universally found in the fog water samples. Naphthalene (NaP), phenanthrene (Phe), anthracene (Ant) and fluoranthene (Flo) were dominant compounds in fog water. The total PAH concentration in fog water ranged from 0.03 to 6.67 μg L(-1) (mean of 1.06 μg L(-1)), and was much higher in winter than in summer. The concentration of PAHs in fog or rain water decreased after undergoing a pre-rain or pre-fog wash. The average concentration of PAHs was higher in fog than in rain. Diagnostic ratio analysis suggested that petroleum and combustion were the dominant contributors to PAHs in urban Shanghai. Backward trajectories were calculated to determine the origin of the air masses, showing that air masses were mostly from the northeast territory.

Extinction of Light during the Fog Life Cycle: a Result from the ParisFog Experiment

International Nuclear Information System (INIS)

Elias, T.; Haeffelin, M.; Drobinski, P.; Gomes, L.; Rangognio, J.; Bergot, T.; Chazette, P.; Raut, J.-C.; Colomb, M.

2009-01-01

Data set acquired by five particle-dedicated instruments set up on the SIRTA experimental site during the ParisFog field campaign are exploited to document microphysical properties of particles contributing to extinction of visible radiation in variable situations. The case study is a 48-hour period when atmospheric conditions are highly variable: relative humidity changes between 50 and 100%, visibility ranges between 35000 and 65 m, the site is either downwind Paris area either under maritime influence. A dense and homogeneous fog formed by radiative cooling during the 18-19 February night. In 7 hours, visibility decreases from 26 000 m to 65 m, because of transported pollution (factor 3 in visibility reduction), aerosol hydration (factor 20) and aerosol activation (factor 6). According to Mie theory, extinction in clear-sky polluted and unpolluted regimes is due equally to Aitken and accumulation modes. Extinction in haze is due to hydrated aerosols distributed in the accumulation mode, for diameter smaller than 2 μm. Hydrated aerosols of the accumulation mode still contribute to 20-30% extinction in the fog. Measurements show that fog droplets, with diameter included between 2 and 10 μm, contribute to 40% extinction during the first hours of the fog.

Estimating fog-top height through near-surface micrometeorological measurements

NARCIS (Netherlands)

Román-Cascón, Carlos; Yagüe, Carlos; Steeneveld, Gert Jan; Sastre, Mariano; Arrillaga, Jon Ander; Maqueda, Gregorio

2016-01-01

Fog-top height (fog thickness) is very useful information for aircraft maneuvers, data assimilation/validation of Numerical Weather Prediction models or nowcasting of fog dissipation. This variable is usually difficult to determine, since the fog-layer top cannot be observed from the surface. In

An analysis of fog events at Belgrade International Airport

Science.gov (United States)

Veljović, Katarina; Vujović, Dragana; Lazić, Lazar; Vučković, Vladan

2015-01-01

A preliminary study of the occurrence of fog at Belgrade "Nikola Tesla" Airport was carried out using a statistical approach. The highest frequency of fog has occurred in the winter months of December and January and far exceeded the number of fog days in the spring and the beginning of autumn. The exceptionally foggy months, those having an extreme number of foggy days, occurred in January 1989 (18 days), December 1998 (18 days), February 2005 (17 days) and October 2001 (15 days). During the winter months (December, January and February) from 1990 to 2005 (16 years), fog occurred most frequently between 0600 and 1000 hours, and in the autumn, between 0500 and 0800 hours. In summer, fog occurred most frequently between 0300 and 0600 hours. During the 11-year period from 1995 to 2005, it was found that there was a 13 % chance for fog to occur on two consecutive days and a 5 % chance that it would occur 3 days in a row. In October 2001, the fog was observed over nine consecutive days. During the winter half year, 52.3 % of fog events observed at 0700 hours were in the presence of stratus clouds and 41.4 % were without the presence of low clouds. The 6-h cooling observed at the surface preceding the occurrence of fog between 0000 and 0700 hours ranged mainly from 1 to 4 °C. A new method was applied to assess the probability of fog occurrence based on complex fog criteria. It was found that the highest probability of fog occurrence (51.2 %) takes place in the cases in which the relative humidity is above 97 %, the dew-point depression is 0 °C, the cloud base is lower than 50 m and the wind is calm or weak 1 h before the onset of fog.

Estimating fog-top height through near-surface micrometeorological measurements

OpenAIRE

Román Cascón, Carlos; Yagüe Anguis, Carlos; Steeneveld, Gert-Jan; Sastre, Mariano; Arrillaga, Jon Ander; Maqueda Burgos, Gregorio

2016-01-01

Fog-top height (fog thickness) is very useful information for aircraft maneuvers, data assimilation/validation of Numerical Weather Prediction models or nowcasting of fog dissipation. This variable is usually difficult to determine, since the fog-layer top cannot be observed from the surface. In some cases, satellite data, ground remote sensing instruments or atmospheric soundings are used to provide approximations of fog-top height. These instruments are expensive and their data not always a...

Fog chemistry in the Texas-Louisiana Gulf Coast corridor

Science.gov (United States)

Raja, Suresh; Raghunathan, Ravikrishna; Yu, Xiao-Ying; Lee, Taehyoung; Chen, Jing; Kommalapati, Raghava R.; Murugesan, Karthik; Shen, Xinhua; Qingzhong, Yuan; Valsaraj, Kalliat T.; Collett, Jeffrey L.

Fog samples were collected in two population centers of the US Gulf Coast (Houston, Texas and Baton Rouge, Louisiana) using Caltech active strand cloud collectors. A total of 32 fogwater samples were collected in Baton Rouge (November 2004-February 2005) and Houston (February 2006). These samples were analyzed for pH, total and dissolved organic carbon, major inorganic ions, and a variety of organic compounds including organic acids, aromatics, carbonyls, and linear alkanes. Fogs in both environments were of moderate density, with typical fog liquid water contents <100 mg m -3. Fog samples collected in Houston reflect a clear influence of marine and anthropogenic inputs, while Baton Rouge samples also reflect agricultural inputs. The volume-weighted mean fog pH was somewhat more acidic (˜4.3) in Houston than in Baton Rouge (˜5.0). A wide pH range was observed in fog at both locations. Houston fog had higher concentrations of Cl -, NO 3-, Na +, Mg 2+, and Ca 2+. Sulfate to nitrate ratios were high in fogs at both locations, typical of many clouds in the eastern US. Total organic carbon concentrations were much higher in Houston fogs than in Baton Rouge fogs. Efforts to speciate dissolved organic carbon (DOC) reveal large contributions from organic acids and carbonyls, with smaller contributions from other organic compound families including aromatics, alkanes, amides, and alcohols. Approximately 40% of the fog DOC was unspeciated in samples from both study locations.

Pollution in coastal fog at Alto Patache, Northern Chile.

Science.gov (United States)

Sträter, Ellen; Westbeld, Anna; Klemm, Otto

2010-11-01

The Atacama Desert in Northern Chile is one of the most arid places on earth. However, fog occurs regularly at the coastal mountain range and can be collected at different sites in Chile to supply settlements at the coast with freshwater. This is also planned in the fog oasis Alto Patache (20°49'S, 70°09'W). For this pilot study, we collected fog water samples in July and August 2008 for chemical analysis to find indications for its suitability for domestic use. Fog water samples were taken with a cylindrical scientific fog collector and from the net and the storage tank of a Large Fog Collector (LFC). The pHs of advective fog, originating from the stratus cloud deck over the Eastern Pacific, varied between 2.9 and 3.5. Orographic fog, which was formed locally, exhibited a pH of 2.5. About 50% of the total ionic concentration was due to sea salt. High percentages of sulfate and very high enrichment factors (versus sea salt) of heavy metals were found. Both backward trajectories and the enrichment factors indicate that the high concentrations of ions and heavy metals in fog were influenced by anthropogenic activities along the Chilean Pacific Coast such as power plants, mining, and steel industry. We found no direct indication for the importance of other sources such as the emission of dimethyl sulfide from the ocean and subsequent atmospheric oxidation for acidity and sulfate or soil erosion for heavy metal concentrations. When fog water was collected by the LFC, it apparently picked up large amounts of dry deposition which accumulated on the nets during fog-free periods. This material is rinsed off the collector shortly after the onset of a fog event with the water collected first. During the first flush, some concentrations of acidity, nitrate, As, and Se, largely exceeded the Chilean drinking water limits. Before any use of fog water for domestic purpose, its quality should be checked on a regular basis. Strategies to mitigate fog water pollution are given.

Channel modeling and performance evaluation of FSO communication systems in fog

KAUST Repository

Esmail, Maged Abdullah

2016-07-01

Free space optical (FSO) communication has become more exciting during the last decade. It has unregulated spectrum with a huge capacity compared to its radio frequency (RF) counterpart. Although FSO has many applications that cover indoor and outdoor environments, its widespread is humped by weather effects. Fog is classified as an extreme weather impairment that may cause link drop. Foggy channel modeling and characterization is necessary to analyze the system performance. In this paper, we first address the statistical behavior of the foggy channel based on a set of literature experimental data and develop a probability distribution function (PDF) model for fog attenuation. We then exploit our PDF model to derive closed form expressions and evaluate the system performance theoretically and numerically, in terms of average signal-to-noise ratio (SNR), and outage probability. The results show that for 10-3 outage probability and 22 dBm transmitted power, the FSO system can work over 80 m, 160 m, 310 m, and 460 m link length under dense, thick, moderate, and light fog respectively. Increasing the transmitted power will have high impact when the fog density is low. However, under very dense fog, it has almost no effect. © 2016 IEEE.

Channel modeling and performance evaluation of FSO communication systems in fog

KAUST Repository

Esmail, Maged Abdullah; Fathallah, Habib; Alouini, Mohamed-Slim

2016-01-01

Free space optical (FSO) communication has become more exciting during the last decade. It has unregulated spectrum with a huge capacity compared to its radio frequency (RF) counterpart. Although FSO has many applications that cover indoor and outdoor environments, its widespread is humped by weather effects. Fog is classified as an extreme weather impairment that may cause link drop. Foggy channel modeling and characterization is necessary to analyze the system performance. In this paper, we first address the statistical behavior of the foggy channel based on a set of literature experimental data and develop a probability distribution function (PDF) model for fog attenuation. We then exploit our PDF model to derive closed form expressions and evaluate the system performance theoretically and numerically, in terms of average signal-to-noise ratio (SNR), and outage probability. The results show that for 10-3 outage probability and 22 dBm transmitted power, the FSO system can work over 80 m, 160 m, 310 m, and 460 m link length under dense, thick, moderate, and light fog respectively. Increasing the transmitted power will have high impact when the fog density is low. However, under very dense fog, it has almost no effect. © 2016 IEEE.

The smog-fog-smog cycle and acid deposition

Science.gov (United States)

Pandis, Spyros N.; Seinfeld, John H.; Pilinis, Christodoulos

1990-10-01

A model including descriptions of aerosol and droplet microphysics, gas and aqueous-phase chemistry, and deposition is used to study the transformation of aerosol to fog droplets and back to aerosol in an urban environment. Fogs in polluted environments have the potential to increase aerosol sulfate concentrations but at the same time to cause reductions in the aerosol concentration of nitrate, chloride, ammonium and sodium and well as in the total aerosol mass concentration. The sulfate produced during fog episodes favors the aerosol particles that have access to most of the fog liquid water which are usually the large particles. Aerosol scavenging efficiencies of around 80 percent are calculated for urban fogs. Sampling and subsequent mixing of fog droplets of different sizes may result in measured concentrations that are not fully representative of the fogwater chemical composition and can introduce errors in the reported values of the ionic species deposition velocities. Differences in the major ionic species deposition velocities can be explained by their distribution over the droplet size spectrum and can be correlated with the species average diameter. Two different expressions are derived for use in fog models for the calculation of the liquid water deposition velocity during fog growth and dissipation stages.

Water fog inerting of hydrogen-air mixtures

International Nuclear Information System (INIS)

Zalosh, R.G.; Bajpai, S.N.

1982-01-01

Laboratory tests have been conducted to determine the effects of water fog density, droplet diameter and temperature on the lower flammable limit (LFL) of hydrogen-air-steam mixtures. Five different fog nozzles were used to generate dense fogs with volume mean drop diameters ranging from 20 micro-meters to 115 micro-meters. At 20 0 C, these nozzles marginally raised the hydrogen LFL from 4.0 vol.% hydrogen to typically 4.8%, with one exceptional nozzle producing an LFL of 7.2%. At 50 0 C, the LFL in the presence of dense fog ranged from 5.0 to 7.9%, while at 70 0 C, the range was 5.9 to 8.5%. Fog densities required to achieve a given level of partial inerting increased with approximately the second power of average drop diameter, as predicted by a theoretical flame quenching analysis

Caltrans fog detection and warning system.

Science.gov (United States)

2009-01-01

The California Department of Transportation (Caltrans) has implemented a fog detection and warning system on Highway 99 near Fresno. The entire central valley region is susceptible to Tule fog, which can reduce visibility tremendously, sometimes to n...

Analysis of prospective systems for fog warnings : [summary].

Science.gov (United States)

2013-01-01

Florida nearly leads the nation in fatal vehicle crashes due to fog and smoke conditions. Between 2002 and 2009, 299 people in Florida died in vehicle crashes related to fog and smoke conditions. In January 2012, heavy fog and smoke were blamed for a...

Referenceless Prediction of Perceptual Fog Density and Perceptual Image Defogging.

Science.gov (United States)

Choi, Lark Kwon; You, Jaehee; Bovik, Alan Conrad

2015-11-01

We propose a referenceless perceptual fog density prediction model based on natural scene statistics (NSS) and fog aware statistical features. The proposed model, called Fog Aware Density Evaluator (FADE), predicts the visibility of a foggy scene from a single image without reference to a corresponding fog-free image, without dependence on salient objects in a scene, without side geographical camera information, without estimating a depth-dependent transmission map, and without training on human-rated judgments. FADE only makes use of measurable deviations from statistical regularities observed in natural foggy and fog-free images. Fog aware statistical features that define the perceptual fog density index derive from a space domain NSS model and the observed characteristics of foggy images. FADE not only predicts perceptual fog density for the entire image, but also provides a local fog density index for each patch. The predicted fog density using FADE correlates well with human judgments of fog density taken in a subjective study on a large foggy image database. As applications, FADE not only accurately assesses the performance of defogging algorithms designed to enhance the visibility of foggy images, but also is well suited for image defogging. A new FADE-based referenceless perceptual image defogging, dubbed DEnsity of Fog Assessment-based DEfogger (DEFADE) achieves better results for darker, denser foggy images as well as on standard foggy images than the state of the art defogging methods. A software release of FADE and DEFADE is available online for public use: http://live.ece.utexas.edu/research/fog/index.html.

Marine sources influence fog bioaerosol composition in Namibia and Maine

Science.gov (United States)

Evans, S. E.; Dueker, E.; Logan, J. R. V.; Weathers, K. C.

2017-12-01

Organic aerosol particles act as condensation nuclei for fogs and clouds (CCN) and are main determinants of fog evolution, chemical processing, and overall aerosol-fog-cloud interactions. Recent work has confirmed the presence of marine bioaerosols, but little is known about their sources, transport, taxonomic diversity or viability. The few studies that have characterized bioaerosols in fog have been limited to culture-based approaches that capture only a fraction of microbial diversity. We characterized fungal and bacterial communities in the fog in two iconic fog systems, the Coast of Maine (USA) and the Namib Desert (Namibia). The biology of fog in both systems was diverse and distinct, by geography, from dry aerosols, and from local sources. The local environment had a dominant influence on fog in both the Namib and Maine; in particular, the biology of fog in Maine, which was collected near the coast, was more similar to microbial communities from the ocean surface. In both systems, differences between pre- and post-fog aerosol communities suggest that fog events can significantly alter microbial aerosol diversity and composition. This insight into the microbial composition of fog indicates that its origin and frequency has the potential to influence the number and diversity of microorganisms that settle in a given environment, and the composition of microbial aerosol communities in ambient or clear conditions. Here we suggest that fog microbes can possess specific traits that enhance nucleation, altering the transport and deposition of marine- and soil-derived organic matter in terrestrial systems.

Fog Simulations Based on Multi-Model System: A Feasibility Study

Science.gov (United States)

Shi, Chune; Wang, Lei; Zhang, Hao; Zhang, Su; Deng, Xueliang; Li, Yaosun; Qiu, Mingyan

2012-05-01

Accurate forecasts of fog and visibility are very important to air and high way traffic, and are still a big challenge. A 1D fog model (PAFOG) is coupled to MM5 by obtaining the initial and boundary conditions (IC/BC) and some other necessary input parameters from MM5. Thus, PAFOG can be run for any area of interest. On the other hand, MM5 itself can be used to simulate fog events over a large domain. This paper presents evaluations of the fog predictability of these two systems for December of 2006 and December of 2007, with nine regional fog events observed in a field experiment, as well as over a large domain in eastern China. Among the simulations of the nine fog events by the two systems, two cases were investigated in detail. Daily results of ground level meteorology were validated against the routine observations at the CMA observational network. Daily fog occurrences for the two study periods was validated in Nanjing. General performance of the two models for the nine fog cases are presented by comparing with routine and field observational data. The results of MM5 and PAFOG for two typical fog cases are verified in detail against field observations. The verifications demonstrated that all methods tended to overestimate fog occurrence, especially for near-fog cases. In terms of TS/ETS, the LWC-only threshold with MM5 showed the best performance, while PAFOG showed the worst. MM5 performed better for advection-radiation fog than for radiation fog, and PAFOG could be an alternative tool for forecasting radiation fogs. PAFOG did show advantages over MM5 on the fog dissipation time. The performance of PAFOG highly depended on the quality of MM5 output. The sensitive runs of PAFOG with different IC/BC showed the capability of using MM5 output to run the 1D model and the high sensitivity of PAFOG on cloud cover. Future works should intensify the study of how to improve the quality of input data (e.g. cloud cover, advection, large scale subsidence) for the 1D

Characteristics of a Dry Fog Ionizer

International Nuclear Information System (INIS)

Murata, Y; Kudo, Y; Yonezawa, M

2008-01-01

The newly developed 'Dry Fog Ionizer' generates charged dry fog. The dry fog consists of very fine water droplets 8μm in mean diameter. This system consists of a dry fog nozzle (H.Ikeuchi and Co., LTD.), a ring electrode for induction charging (50mm outside diameter, and 10mm thick) in front of the nozzle, and a fan for dissipating charged dry fog. The ring electrode is DC or AC-biased and fine droplets ejected from the nozzle are electrified by induction charging. The particle size of the charged water droplets are reduced through evaporation during the transporting process by air flow, and completely evaporate approximately 2m from the nozzle under normal atmospheric conditions (25 deg. C, 60%R.H.) leaving high density ions. Using this system, high density ionic space charge can be realized in a remote spot from the ionizer. By this principle, the Dry Fog Ionizer shows strong charge-eliminating ability in the region away from the ionizer. When a dc bias of 5kV was applied to a ring electrode with the rate of water flow from the nozzle being 21/h, an ionic space-charge density of 1200nC /m 3 was able to be obtained at a distance 2m away from the ionizer, which was 10 2 times the value produced by an ordinary corona-type ionizer with an air blower.

Daily lifestyles in the fog and haze weather.

Science.gov (United States)

Cai, Dong-Ping; He, Yong-Ming

2016-01-01

China is being plagued by a large-scaled lasting fog and haze, under which people have to work and live. Therefore, it matters to do what we can to minimize the adverse impact of the fog and haze on individual health on a daily basis. Relative literatures on the fog and haze have been searched and reviewed. Particular attention has been paid to the literatures on the adverse impact of the fog and haze on the people's health and on the ways minimizing this impact. Coming across the weather of fog and haze, appropriate measures taken can minimize its adverse impact on individuals on a daily basis. The measures included vitamin intake, water drinking, air cleaning indoors, stay-at-home, and mask wearing outdoors. These measures are simple and proven effective. Simple and effective measures seem to be sufficient to minimizing the adverse impact of the fog and haze on the individual's health on a daily basis. Lifestyle changes, awareness of environment protection, energy conservation, and new and clean energy use are ultimate ways to curb the air pollution and reduce the occurrence of the fog and haze.

X-ray measurements of water fog density

International Nuclear Information System (INIS)

Camp, A.L.

1982-11-01

Water-fog densities were measured in a laboratory experiment using x-ray diagnostics. Fog densities were measured, varying the flow rate, nozzle type, nozzle configuration, nozzle height above the x-ray beam, and water surface tension. Suspended water volume fractions between 0.0008 and 0.0074 percent were measured. The fog density increases approximately as the square root of the flow rate; the other parameters had little effect on the density

Winter Frost and Fog

Science.gov (United States)

2005-01-01

This somewhat oblique blue wide angle Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the 174 km (108 mi) diameter crater, Terby, and its vicinity in December 2004. Located north of Hellas, this region can be covered with seasonal frost and ground-hugging fog, even in the afternoon, despite being north of 30oS. The subtle, wavy pattern is a manifestation of fog. Location near: 28oS, 286oW Illumination from: upper left Season: Southern Winter

Current status of acid fog research. Sanseimu kenkyu no genjo

Energy Technology Data Exchange (ETDEWEB)

Murano, K. (National Inst. for Environmental Studies, Tsukuba (Japan))

1993-07-10

Acid fog research was behind in comparison with acid rain research. In case of acid fog, it is because the place generating sufficiently thick fog to collect is limited, the generating place is mountainous, its survey needs a lot of works, its collector is not convenient like in acid rain, or its sampling is difficult on its automation. Since the 1980s, an extensive survey on acid fog had been carried out centering the west coast of California, USA, and low pH fog (minimum pH 2.2) was observed. In the course of these researches, string type active fogwater collectors became a major sampling method, and the simulation of acidification of fog droplet in the atmosphere was extensively conducted. In Japan, already in the 1960s, field surveys on acid fog were conducted, in 1984 acid fog survey started on Mt. Akagi under a viewpoint of ecological impact, and there was a report that low pH fog (pH 3 to 4) continued more than 10 hours. It was pointed out that there were plant damage by acid fog in several locations, especially the tree mortality mechanism in Tomakomai was clarified. 50 refs., 10 figs., 6 tabs.

Security and Privacy in Fog Computing: Challenges

OpenAIRE

Mukherjee, Mithun; Matam, Rakesh; Shu, Lei; Maglaras, Leandros; Ferrag, Mohamed Amine; Choudhry, Nikumani; Kumar, Vikas

2017-01-01

open access article Fog computing paradigm extends the storage, networking, and computing facilities of the cloud computing toward the edge of the networks while offloading the cloud data centers and reducing service latency to the end users. However, the characteristics of fog computing arise new security and privacy challenges. The existing security and privacy measurements for cloud computing cannot be directly applied to the fog computing due to its features, such as mobility, heteroge...

Evaluation of fog predictions and detection.

Science.gov (United States)

2015-03-01

On January 29, 2012 at about 4:00 am a thick fog and smoke caused a multiple car : crash just south of Gainesville, Florida. 11 people were killed and 18 were : hospitalized. Nationally there are about 38,000 fog related accidents which result in : a...

Mesh Intercomparisons of Fog Water Collected Yield Insight Into the Nature of Fog-Drip Collection Mechanisms

Science.gov (United States)

Fernandez, D.; Torregrosa, A.; Weiss-Penzias, P. S.; Oliphant, A. J.; Dodge, C.; Bowman, M.; Wilson, S.; Mairs, A. A.; Gravelle, M.; Barkley, T.

2016-12-01

At multiple sites across central CA, several passive fog water collectors have been deployed for the past 3 years. All of the sites employ standard Raschel polypropylene mesh as the fog collection medium and five of them also integrated a novel polypropylene mesh of German manufacture with a 3-dimensional internal structure. Additionally, six metal mesh manufactured by McMaster-Carr of various hole sizing were coated with a POSS-PEMA substance at the Massachusetts Institute of Technology and deployed in parallel with the Raschel mesh at six distinct locations. Finally, fluorine-free versions of the POSS-PEMA substance were generated by NBD Nanotechnology and coated on a much finer mesh substrate. Three of those and one control (uncoated mesh) were deployed at one of the fog collection sites for one season, along with a standard Raschel mesh. Preliminary results from one intercomparison from just one pair of mesh over two seasons seem to reveal a wind speed and also, possibly, a droplet-size dependence on the fog collection efficiency for the mesh. This study will continue to intercompare the various mesh in conjunction with the wind speed and direction data. If a collection efficiency dependence on mesh size or coating is confirmed, it may point to interesting and relevant mechanisms for fog droplet capture and collection hitherto unobserved in field conditions.

Lambda-Lifting in Quadratic Time

DEFF Research Database (Denmark)

Danvy, Olivier; Schultz, Ulrik Pagh

2002-01-01

Lambda-lifting is a program transformation used in compilers and in partial evaluators and that operates in cubic time. In this article, we show how to reduce this complexity to quadratic time. Lambda-lifting transforms a block-structured program into a set of recursive equations, one for each...... local function in the source program. Each equation carries extra parameters to account for the free variables of the corresponding local function and of all its callees. It is the search for these extra parameters that yields the cubic factor in the traditional formulation of lambda-lifting, which...... is not needed. We therefore simplify the search for extra parameters by treating each strongly connected component instead of each function as a unit, thereby reducing the time complexity of lambda-lifting from O(n 3 log n)toO(n2 log n), where n is the size of the program. Since a lambda-lifter can output...

Service Migration from Cloud to Multi-tier Fog Nodes for Multimedia Dissemination with QoE Support.

Science.gov (United States)

Rosário, Denis; Schimuneck, Matias; Camargo, João; Nobre, Jéferson; Both, Cristiano; Rochol, Juergen; Gerla, Mario

2018-01-24

A wide range of multimedia services is expected to be offered for mobile users via various wireless access networks. Even the integration of Cloud Computing in such networks does not support an adequate Quality of Experience (QoE) in areas with high demands for multimedia contents. Fog computing has been conceptualized to facilitate the deployment of new services that cloud computing cannot provide, particularly those demanding QoE guarantees. These services are provided using fog nodes located at the network edge, which is capable of virtualizing their functions/applications. Service migration from the cloud to fog nodes can be actuated by request patterns and the timing issues. To the best of our knowledge, existing works on fog computing focus on architecture and fog node deployment issues. In this article, we describe the operational impacts and benefits associated with service migration from the cloud to multi-tier fog computing for video distribution with QoE support. Besides that, we perform the evaluation of such service migration of video services. Finally, we present potential research challenges and trends.

Experimental Study Of Fog Water Harvesting By Stainless Steel Mesh

Directory of Open Access Journals (Sweden)

Nikhil R. Pawar

2017-06-01

Full Text Available The collection of fog water is a simple and sustainable technology to get hold of fresh water for various purposes. In areas where a substantial amount of fog can be obtained it is feasible to set up a stainless steel as well as black double layer plastic mesh structure for fog water harvesting. The mesh structure is directly exposed to the weather and the fog containing air is pushed through the active mesh surface by the wind. Afterward fog droplets are deposited on the active mesh area which combines to form superior droplets and run down into a gutter to storage by gravity. Fog water harvesting rates show a discrepancy from site to site. The scope of this experimental work is to review fog collection at SCOE Pune campus and to examine factors of success. This study is to synthesize the understanding of fog water harvesting in the institutional era and to analyze its benefits and boundaries for future development. The rate of fog water harvesting depends on the science of fog physics chemistry and its starring role in the hydrological cycle. This technology runs on zero energy and zeroes pollution level with cost of the benefit. The collected or treated clear water mainly could be used for different purposes as per requirement. For further development this technology public as well as government participation is needed.

Fog along the Meuse Valley

Energy Technology Data Exchange (ETDEWEB)

Firket, J

1936-01-01

An account of a fog-pollution incident, 1 through 5 December 1930 was described. Many people were injured, several hundred were severely hampered by respiratory troubles, and 63 people died on December 4 and 5. Many cattle were slaughtered because of sickness. Symptoms coincided with the arrival and departure of fog. Medical conditions included: retrosternal pain, coughing fits, dypsnea similar to that accompanying asthma, cardiovascular collapse in those particularly susceptible (e.g., already crippled by asthma or cardiac insufficiency), irritation of respiratory membranes, and deposition of fine soot as far as alveoli. Retrospective observation and calculation pointed to SO/sub 2/ from burning of coal and sulfuric acid from fog-metal oxide-catalyzed conversion of SO/sub 2/ as the possible deadly pollutants. Maximum (calculated) SO/sub 2/ concentration was 100 mg/m/sup 3/.

Baby Shampoo versus Commercial Anti-fogging Solution to Prevent Fogging during Nasal Endoscopy: A Randomized Double-Blinded, Matched-Pair, Equivalent Trial.

Science.gov (United States)

Chainansamit, Seksun; Piromchai, Patorn; Anantpinijwatna, Intira; Kasemsiri, Pornthep; Thanaviratananich, Sanguansak

2015-08-01

To compare the minimization of the fog condensation during nasal endoscopy between a commercial anti-fogging agent and baby shampoo. This randomized double-blinded matched pair study was conducted at the Department of Otorhinolaryngology, Faculty of Medicine, Khon Kaen University during February 4, 2013 to March 14, 2013. The commercial anti-fogging solution (Ultrastop®) and baby shampoo solution (Johnson's® no more tear®) were compared. A computer generated randomization was performed to select the solution applying on the lens for nasal endoscopy of the right nasal cavity. The other solution was then used for the left one. Three passes of endoscopy were performed to examine the floor of the nose, the sphenoethmoidal recess and the middle meatus area which spent about 30 seconds for each time of endoscopy. The time to become foggy on the lens and the preferred solution assessed by the endoscopists were recorded. There were 71 eligible patients recruited in the study, 37 males (52.1%) and 34 females (47.9%). There was no fogging during a 30-second nasal endoscopy either by baby shampoo or commercial anti-fogging solution. However, 9.86% (95% C12.75-16.97) of endoscopists preferred commercial anti-fogging agent, 7.04% (95% CI 0.94-13.14) preferred baby shampoo and 83.10% (95% CI 74.16-92.03) had equal satisfaction. Both agents had no statistically significant difference for preventing foggy on the lens. Baby shampoo is an effective agent to prevent fogging during nasal endoscopy and comparable with the commercial anti-fogging agent.

An improved measurement system for FOG pure lag time with no changing of FOG work status

Science.gov (United States)

Chen, X.; Yang, J. H.; Zhou, Y. L.; Shu, X. W.

2018-05-01

The minimum pure lag time is an important factor for characterizing the dynamic performance of fiber optical gyroscope. It is defined as the time duration from the reception of velocity-shock signal to the output of corresponding fiber-optic gyroscope data. Many engineering projects have required for this index specifically, so the measurement of the minimum pure lag time is highly demanded. In typically measurement system, the work status of tested FOG has to be changed. In this work, a FOG pure lag time measurement system without changing the work status of the FOG has been demonstrated. During the operation of this test system, the impact structure generated a shock towards the FOG, and the pure lag time was measured through data processing analysis. The design scheme and test principle have been researched and analyzed in detail. And a prototype has been developed and used for experiment successfully. This measurement system can realize a measurement accuracy of better than ±3 μs and a system resolution of 108.6ns.

Fog interception by Ball moss (Tillandsia recurvata)

Science.gov (United States)

Guevara-Escobar, A.; Cervantes-Jiménez, M.; Suzán-Azpiri, H.; González-Sosa, E.; Hernández-Sandoval, L.; Malda-Barrera, G.; Martínez-Díaz, M.

2011-08-01

Interception losses are a major influence in the water yield of vegetated areas. For most storms, rain interception results in less water reaching the ground. However, fog interception can increase the overall water storage capacity of the vegetation and once the storage is exceeded, fog drip is a common hydrological input. Fog interception is disregarded in water budgets of semiarid regions, but for some plant communities, it could be a mechanism offsetting evaporation losses. Tillandsia recurvata is a cosmopolitan epiphyte adapted to arid habitats where fog may be an important water source. Therefore, the interception storage capacity by T. recurvata was measured in controlled conditions and applying simulated rain or fog. Juvenile, vegetative specimens were used to determine the potential upperbound storage capacities. The storage capacity was proportional to dry weight mass. Interception storage capacity (Cmin) was 0.19 and 0.56 mm for rainfall and fog respectively. The coefficients obtained in the laboratory were used together with biomass measurements for T. recurvata in a xeric scrub to calculate the depth of water intercepted by rain. T. recurvata contributed 20 % to the rain interception capacity of their shrub hosts: Acacia farnesiana and Prosopis laevigata and; also potentially intercepted 4.8 % of the annual rainfall. Nocturnal stomatic opening in T. recurvata is not only relevant for CO2 but for water vapor, as suggested by the higher weight change of specimens wetted with fog for 1 h at dark in comparison to those wetted during daylight (543 ± 77 vs. 325 ± 56 mg, p = 0.048). The storage capacity of T. recurvata leaf surfaces could increase the amount of water available for evaporation, but as this species colonise montane forests, the effect could be negative on water recharge, because potential storage capacity is very high, in the laboratory experiments it took up to 12 h at a rate of 0.26 l h-1 to reach saturation conditions when fog was applied.

Fog interception by Ball moss (Tillandsia recurvata

Directory of Open Access Journals (Sweden)

G. Malda-Barrera

2011-08-01

Full Text Available Interception losses are a major influence in the water yield of vegetated areas. For most storms, rain interception results in less water reaching the ground. However, fog interception can increase the overall water storage capacity of the vegetation and once the storage is exceeded, fog drip is a common hydrological input. Fog interception is disregarded in water budgets of semiarid regions, but for some plant communities, it could be a mechanism offsetting evaporation losses. Tillandsia recurvata is a cosmopolitan epiphyte adapted to arid habitats where fog may be an important water source. Therefore, the interception storage capacity by T. recurvata was measured in controlled conditions and applying simulated rain or fog. Juvenile, vegetative specimens were used to determine the potential upperbound storage capacities. The storage capacity was proportional to dry weight mass. Interception storage capacity (Cmin was 0.19 and 0.56 mm for rainfall and fog respectively. The coefficients obtained in the laboratory were used together with biomass measurements for T. recurvata in a xeric scrub to calculate the depth of water intercepted by rain. T. recurvata contributed 20 % to the rain interception capacity of their shrub hosts: Acacia farnesiana and Prosopis laevigata and; also potentially intercepted 4.8 % of the annual rainfall. Nocturnal stomatic opening in T. recurvata is not only relevant for CO2 but for water vapor, as suggested by the higher weight change of specimens wetted with fog for 1 h at dark in comparison to those wetted during daylight (543 ± 77 vs. 325 ± 56 mg, p = 0.048. The storage capacity of T. recurvata leaf surfaces could increase the amount of water available for evaporation, but as this species colonise montane forests, the effect could be negative on water recharge, because potential storage capacity is very high, in the laboratory experiments it took up to 12 h at a rate of 0.26 l h−1 to reach saturation conditions

IoT Stream Processing and Analytics in The Fog

OpenAIRE

Yang, Shusen

2017-01-01

The emerging Fog paradigm has been attracting increasing interests from both academia and industry, due to the low-latency, resilient, and cost-effective services it can provide. Many Fog applications such as video mining and event monitoring, rely on data stream processing and analytics, which are very popular in the Cloud, but have not been comprehensively investigated in the context of Fog architecture. In this article, we present the general models and architecture of Fog data streaming, ...

Fog as a fresh-water resource: overview and perspectives.

Science.gov (United States)

Klemm, Otto; Schemenauer, Robert S; Lummerich, Anne; Cereceda, Pilar; Marzol, Victoria; Corell, David; van Heerden, Johan; Reinhard, Dirk; Gherezghiher, Tseggai; Olivier, Jana; Osses, Pablo; Sarsour, Jamal; Frost, Ernst; Estrela, María J; Valiente, José A; Fessehaye, Gebregiorgis Mussie

2012-05-01

The collection of fog water is a simple and sustainable technology to obtain fresh water for afforestation, gardening, and as a drinking water source for human and animal consumption. In regions where fresh water is sparse and fog frequently occurs, it is feasible to set up a passive mesh system for fog water collection. The mesh is directly exposed to the atmosphere, and the foggy air is pushed through the mesh by the wind. Fog droplets are deposited on the mesh, combine to form larger droplets, and run down passing into a storage tank. Fog water collection rates vary dramatically from site to site but yearly averages from 3 to 10 l m(-2) of mesh per day are typical of operational projects. The scope of this article is to review fog collection projects worldwide, to analyze factors of success, and to evaluate the prospects of this technology.

Animal or plant: which is the better fog water collector?

Science.gov (United States)

Nørgaard, Thomas; Ebner, Martin; Dacke, Marie

2012-01-01

Occasional fog is a critical water source utilised by plants and animals in the Namib Desert. Fog basking beetles (Onymacris unguicularis, Tenebrionidae) and Namib dune bushman grass (Stipagrostris sabulicola, Poaceae) collect water directly from the fog. While the beetles position themselves optimally for fog water collection on dune ridges, the grass occurs predominantly at the dune base where less fog water is available. Differences in the fog-water collecting abilities in animals and plants have never been addressed. Here we place beetles and grass side-by-side in a fog chamber and measure the amount of water they collect over time. Based on the accumulated amount of water over a two hour period, grass is the better fog collector. However, in contrast to the episodic cascading water run-off from the grass, the beetles obtain water in a steady flow from their elytra. This steady trickle from the beetles' elytra to their mouth could ensure that even short periods of fog basking--while exposed to predators--will yield water. Up to now there is no indication of specialised surface properties on the grass leafs, but the steady run-off from the beetles could point to specific property adaptations of their elytra surface.

Animal or plant: which is the better fog water collector?

Directory of Open Access Journals (Sweden)

Thomas Nørgaard

Full Text Available Occasional fog is a critical water source utilised by plants and animals in the Namib Desert. Fog basking beetles (Onymacris unguicularis, Tenebrionidae and Namib dune bushman grass (Stipagrostris sabulicola, Poaceae collect water directly from the fog. While the beetles position themselves optimally for fog water collection on dune ridges, the grass occurs predominantly at the dune base where less fog water is available. Differences in the fog-water collecting abilities in animals and plants have never been addressed. Here we place beetles and grass side-by-side in a fog chamber and measure the amount of water they collect over time. Based on the accumulated amount of water over a two hour period, grass is the better fog collector. However, in contrast to the episodic cascading water run-off from the grass, the beetles obtain water in a steady flow from their elytra. This steady trickle from the beetles' elytra to their mouth could ensure that even short periods of fog basking--while exposed to predators--will yield water. Up to now there is no indication of specialised surface properties on the grass leafs, but the steady run-off from the beetles could point to specific property adaptations of their elytra surface.

New method for evaluating high-quality fog protective coatings

Science.gov (United States)

Czeremuszkin, Grzegorz; Latreche, Mohamed; Mendoza-Suarez, Guillermo

2011-05-01

Fogging is commonly observed when humid-warm air contacts the cold surface of a transparent substrate, i.e. eyewear lenses, making the observed image blurred and hazy. To protect from fogging, the lens inner surfaces are protected with Anti-Fog coatings, which render them hydrophilic and induce water vapor condensation as a smooth, thin and invisible film, which uniformly flows down on the lens as the condensation progresses. Coatings differ in protection level, aging kinetics, and susceptibility to contamination. Some perform acceptably in limited conditions, beyond which the condensing water film becomes unstable, nonuniform, and scatters light or shows refractory distortions, both affecting the observed image. Quantifying the performance of Anti-Fog coated lenses is difficult: they may not show classical fogging and the existing testing methods, based on fog detection, are therefore inapplicable. The presented method for evaluating and quantifying AF properties is based on characterizing light scattering on lenses exposed to controlled humidity and temperature. Changes in intensity of laser light scattered at low angles (1, 2 4 and 8 degrees), observed during condensation of water on lenses, provide information on the swelling of Anti-Fog coatings, formation of uniform water film, going from an unstable to a steady state, and on the coalescence of discontinuous films. Real time observations/measurements allow for better understanding of factors controlling fogging and fog preventing phenomena. The method is especially useful in the development of new coatings for military-, sport-, and industrial protective eyewear as well as for medical and automotive applications. It allows for differentiating between coatings showing acceptable, good, and excellent performance.

Coastal Fog Sustains Summer Baseflow in Northern Californian Watershed

Science.gov (United States)

Chung, M.; Dufour, A.; Leonardson, R.; Thompson, S. E.; Dawson, T. E.

2015-12-01

The Mediterranean climate of Northern California imposes significant water stress on ecosystems and water resources during the dry summer months. During summer, frequently the only water inputs occur as occult precipitation, in the form of fog and dew. In this study, we characterized the role of coastal fog, a dominant feature of Northern Californian coastal ecosystems and a widespread phenomenon associated with deep marine upwelling in west coast, arid, and Mediterranean climates worldwide. We monitored fog occurrence and intensity, throughfall following canopy interception of fog, soil moisture, streamflow, and meteorological variables, and made visual observations of the spatial extent of fog using time-lapse imagery in Upper Pilarcitos Creek Watershed (managed by San Francisco Public Utilities Commission as part of the San Francisco area water supply). We adopted a stratified sampling design that captured the watershed's elevation gradient, forest-edge versus interior locations, and different vegetation cover. The point-scale observations of throughfall inputs and transpiration suppression, estimated from the Penman equation, were upscaled using such watershed features and the observed fog "footprint" identified from the time-lapse images. When throughfall input and fog-induced transpiration suppression were incorporated into the operational watershed model, they improved estimates of summer baseflow, which remained persistently higher than could be explained without the fog effects. Fog, although providing relatively small volumetric inputs to the water balance, appears to offer significant relief of water stress throughout the terrestrial and aquatic components of the coastal Californian ecosystem and thus should be accounted for when assessing water stress availability in dry ecosystems.

Prediction of fog/visibility over India using NWP Model

Science.gov (United States)

Singh, Aditi; George, John P.; Iyengar, Gopal Raman

2018-03-01

Frequent occurrence of fog in different parts of northern India is common during the winter months of December and January. Low visibility conditions due to fog disrupt normal public life. Visibility conditions heavily affect both surface and air transport. A number of flights are either diverted or cancelled every year during the winter season due to low visibility conditions, experienced at different airports of north India. Thus, fog and visibility forecasts over plains of north India become very important during winter months. This study aims to understand the ability of a NWP model (NCMRWF, Unified Model, NCUM) with a diagnostic visibility scheme to forecast visibility over plains of north India. The present study verifies visibility forecasts obtained from NCUM against the INSAT-3D fog images and visibility observations from the METAR reports of different stations in the plains of north India. The study shows that the visibility forecast obtained from NCUM can provide reasonably good indication of the spatial extent of fog in advance of one day. The fog intensity is also predicted fairly well. The study also verifies the simple diagnostic model for fog which is driven by NWP model forecast of surface relative humidity and wind speed. The performance of NWP model forecast of visibility is found comparable to that from simple fog model driven by NWP forecast of relative humidity and wind speed.

Measurements of fog composition at a rural site

Science.gov (United States)

Straub, Derek J.; Hutchings, James W.; Herckes, Pierre

2012-02-01

Studies that focus on fog chemistry in the United States have been limited to relatively few locations. Apart from measurements along the East and West coasts and extensive analysis of radiation fog in the Central Valley of California, fog composition has been characterized in only a handful of other locations. To complement and expand the existing fog chemistry data that are currently available, a new field campaign was established at a rural location in Central Pennsylvania to produce a unique, long term record of fog composition. From 2007 to 2010, 41 fog events were sampled with an automated Caltech Heated Rod Cloudwater Collector (CHRCC). The collected samples were analyzed primarily for pH and major inorganic ions. Dissolved organic carbon (DOC) and trace metals were analyzed in selected samples and N-nitrosodimethylamine (NDMA) was quantified in two samples. Sample composition varied widely during the study period. Sulfate concentrations ranged from 15 to 955 (median = 123) μN and pH varied between 3.08 and 7.41 (median = 5.77). In terms of volume weighted averages, ammonium was the most abundant ionic species followed by sulfate, calcium, and nitrate. For the subset of samples in which DOC was analyzed, concentrations ranged from 2.2 to 22.6 mgC l -1. Comparisons with regional precipitation chemistry measurements reveal the influence of local agricultural and soil sources on fog composition. The sum of sulfate, nitrate, and ammonium measured in the present study is considerably lower than the majority of radiation, precipitation, and coastal fogs collected in the United States although the ammonium/(nitrate + sulfate) ratio is similar to those found in the Central Valley of California.

Fog Occurrence and Associated Meteorological Factors Over Kempegowda International Airport, India

Science.gov (United States)

Kutty, Saumya G.; Agnihotri, G.; Dimri, A. P.; Gultepe, I.

2018-05-01

The increase in fog frequency over the past few decades is a major cause of concern for the aviation and transportation sectors. Accurate forecasting of the spatio-temporal extent of fog is crucial for minimizing socioeconomic losses. The present study attempts to characterize the fog frequency and associated meteorological factors over Kempegowda International Airport, Bengaluru (KIAB), in Karnataka, India. Maximum fog occurrence is observed during the month of December, followed by January. The time of onset of fog lies usually between 1800 and 0300 UTC. No fog is formed between 0400 and 1700 UTC indicating the role of radiation fog. The predominant wind direction during fog events is east or southeasterly. There is significant positive correlation between the fog frequency and both the northeast monsoon, October-November (0.72), as well as December-January-February (DJF) rainfall (0.80). Soil moisture conditions during the DJF period also play a key role in fog occurrence and its climatology, which is evident from the correlation coefficient of order 0.68. These suggest that further research is needed for understanding the extent of impact on aviation at KIAB.

Smart Fog: Fog Computing Framework for Unsupervised Clustering Analytics in Wearable Internet of Things

OpenAIRE

Borthakur, Debanjan; Dubey, Harishchandra; Constant, Nicholas; Mahler, Leslie; Mankodiya, Kunal

2017-01-01

The increasing use of wearables in smart telehealth generates heterogeneous medical big data. Cloud and fog services process these data for assisting clinical procedures. IoT based ehealthcare have greatly benefited from efficient data processing. This paper proposed and evaluated use of low resource machine learning on Fog devices kept close to the wearables for smart healthcare. In state of the art telecare systems, the signal processing and machine learning modules are deployed in the clou...

Fog at the Guarulhos International Airport from 1951 to 2015

Science.gov (United States)

França, Gutemberg Borges; do Carmo, Luiz Felipe Rodrigues; de Almeida, Manoel Valdonel; Albuquerque Neto, Francisco Leite

2018-02-01

This paper presents and discusses the fog occurrences before and after the construction of the Guarulhos International Airport, using data from 1951 to 2015. The analysis showed the following: (1) a total of 19,816 h of fog were registered. (2) The minimum average, mean and maximum average of the fog temperature had significantly increased after the airport was constructed from 1.2 to 6.9, 12.1 to 14.5 and 20.2 to 20.7 °C, respectively, due to the urban development around the airport during the study period. (3) The average fog hours per year decreased by approximately 73.1%, i.e., from 492 ± 84.45 to 132 ± 54.51 h per year. (4) Most of the fog events occurred due to longwave cooling on clear nights with relatively low wind speeds (characterizing radiation fog), with over 65% having duration of 2 h and occurring in the early hours of the day during March-September period. (5) The maximum probability of fog occurrence dropped about 10% from before to after the construction of the airport. Finally, two fog events are investigated using data collected during the fog evolution using atmospheric sounding profiles (from an acoustic sounder) and automatic meteorological stations and preliminary results showed that the values of cooling rate and turbulent kinetic energy play key roles in the onset and growth-dissipation phases of the fog, respectively.

The impact of fog on soil moisture dynamics in the Namib Desert

Science.gov (United States)

Li, Bonan; Wang, Lixin; Kaseke, Kudzai F.; Vogt, Roland; Li, Lin; Seely, Mary K.

2018-03-01

Soil moisture is a crucial component supporting vegetation dynamics in drylands. Despite increasing attention on fog in dryland ecosystems, the statistical characterization of fog distribution and how fog affects soil moisture dynamics have not been seen in literature. To this end, daily fog records over two years (Dec 1, 2014-Nov 1, 2016) from three sites within the Namib Desert were used to characterize fog distribution. Two sites were located within the Gobabeb Research and Training Center vicinity, the gravel plains and the sand dunes. The third site was located at the gravel plains, Kleinberg. A subset of the fog data during rainless period was used to investigate the effect of fog on soil moisture. A stochastic modeling framework was used to simulate the effect of fog on soil moisture dynamics. Our results showed that fog distribution can be characterized by a Poisson process with two parameters (arrival rate λ and average depth α (mm)). Fog and soil moisture observations from eighty (Aug 19, 2015-Nov 6, 2015) rainless days indicated a moderate positive relationship between soil moisture and fog in the Gobabeb gravel plains, a weaker relationship in the Gobabeb sand dunes while no relationship was observed at the Kleinberg site. The modeling results suggested that mean and major peaks of soil moisture dynamics can be captured by the fog modeling. Our field observations demonstrated the effects of fog on soil moisture dynamics during rainless periods at some locations, which has important implications on soil biogeochemical processes. The statistical characterization and modeling of fog distribution are of great value to predict fog distribution and investigate the effects of potential changes in fog distribution on soil moisture dynamics.

Novel method for fog monitoring using cellular networks infrastructures

Science.gov (United States)

David, N.; Alpert, P.; Messer, H.

2012-08-01

A major detrimental effect of fog is visibility limitation which can result in serious transportation accidents, traffic delays and therefore economic damage. Existing monitoring techniques including satellites, transmissometers and human observers - suffer from low spatial resolution, high cost or lack of precision when measuring near ground level. Here we show a novel technique for fog monitoring using wireless communication systems. Communication networks widely deploy commercial microwave links across the terrain at ground level. Operating at frequencies of tens of GHz they are affected by fog and are, effectively, an existing, spatially world-wide distributed sensor network that can provide crucial information about fog concentration and visibility. Fog monitoring potential is demonstrated for a heavy fog event that took place in Israel. The correlation between transmissomters and human eye observations to the visibility estimates from the nearby microwave links was found to be 0.53 and 0.61, respectively. These values indicate the high potential of the proposed method.

Crowd Sensing-Enabling Security Service Recommendation for Social Fog Computing Systems.

Science.gov (United States)

Wu, Jun; Su, Zhou; Wang, Shen; Li, Jianhua

2017-07-30

Fog computing, shifting intelligence and resources from the remote cloud to edge networks, has the potential of providing low-latency for the communication from sensing data sources to users. For the objects from the Internet of Things (IoT) to the cloud, it is a new trend that the objects establish social-like relationships with each other, which efficiently brings the benefits of developed sociality to a complex environment. As fog service become more sophisticated, it will become more convenient for fog users to share their own services, resources, and data via social networks. Meanwhile, the efficient social organization can enable more flexible, secure, and collaborative networking. Aforementioned advantages make the social network a potential architecture for fog computing systems. In this paper, we design an architecture for social fog computing, in which the services of fog are provisioned based on "friend" relationships. To the best of our knowledge, this is the first attempt at an organized fog computing system-based social model. Meanwhile, social networking enhances the complexity and security risks of fog computing services, creating difficulties of security service recommendations in social fog computing. To address this, we propose a novel crowd sensing-enabling security service provisioning method to recommend security services accurately in social fog computing systems. Simulation results show the feasibilities and efficiency of the crowd sensing-enabling security service recommendation method for social fog computing systems.

Maxillary sinus function after sinus lifts for the insertion of dental implants

NARCIS (Netherlands)

Timmenga, NM; Raghoebar, GM; Boering, G; VanWeissenbruch, R

Purpose: The influence of bone augmentation of the floor of the maxillary sinus for the insertion of denial implants on sinus function has not been well investigated, In this study, the influence of the sinus lift on the development of maxillary sinus pathology was evaluated using generally accepted

Vertical distribution of microphysical properties in radiation fogs - A case study

Science.gov (United States)

Egli, S.; Maier, F.; Bendix, J.; Thies, B.

2015-01-01

The present study investigates the validity of a theoretical liquid water content (LWC) profile in fog layers currently used for satellite based ground fog detection, with a special focus on the temporal dynamics during fog life cycle. For this purpose, LWC profiles recorded during two different fog events by means of a tethered balloon borne measurement system are presented and discussed. The results indicate a good agreement in trend and gradient between measured and theoretical LWC profiles during the mature stage of the fog life cycle. The profile obtained during the dissipation stage shows less accordance with the theoretical profile. To improve the agreement between theoretical and measured LWC profiles, the evolutionary stages during the fog life cycle should be incorporated. However, the variability within the prenoted measurements points out that more LWC profiles during a great variety of different fog events have to be collected for a well-justified adaptation of the theoretical LWC profile, considering fog life cycle phases in the future. In general, this underlines the existing knowledge gap regarding the vertical distribution of microphysical properties in natural fogs.

Hydrophobic/Hydrophilic Cooperative Janus System for Enhancement of Fog Collection.

Science.gov (United States)

Cao, Moyuan; Xiao, Jiasheng; Yu, Cunming; Li, Kan; Jiang, Lei

2015-09-09

Harvesting micro-droplets from fog is a promising method for solving global freshwater crisis. Different types of fog collectors have been extensively reported during the last decade. The improvement of fog collection can be attributed to the immediate transportation of harvested water, the effective regeneration of the fog gathering surface, etc. Through learning from the nature's strategy for water preservation, the hydrophobic/hydrophilic cooperative Janus system that achieved reinforced fog collection ability is reported here. Directional delivery of the surface water, decreased re-evaporation rate of the harvested water, and thinner boundary layer of the collecting surface contribute to the enhancement of collection efficiency. Further designed cylinder Janus collector can facilely achieve a continuous process of efficient collection, directional transportation, and spontaneous preservation of fog water. This Janus fog harvesting system should improve the understanding of micro-droplet collection system and offer ideas to solve water resource crisis. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of fog predictions and detection : [summary].

Science.gov (United States)

2015-03-01

Fog can make driving conditions extremely hazardous. These hazards are further increased : at night and/or when combined with smoke. Nationally, about 38,000 fog-related highway : incidents occur each year, with over 600 fatalities. Florida ranks thi...

Project Fog Drops 5. Task 1: A numerical model of advection fog. Task 2: Recommendations for simplified individual zero-gravity cloud physics experiments

Science.gov (United States)

Rogers, C. W.; Eadie, W. J.; Katz, U.; Kocmond, W. C.

1975-01-01

A two-dimensional numerical model was used to investigate the formation of marine advection fog. The model predicts the evolution of potential temperature, horizontal wind, water vapor content, and liquid water content in a vertical cross section of the atmosphere as determined by vertical turbulent transfer and horizontal advection, as well as radiative cooling and drop sedimentation. The model is designed to simulate the formation, development, or dissipation of advection fog in response to transfer of heat and moisture between the atmosphere and the surface as driven by advection over horizontal discontinuities in the surface temperature. Results from numerical simulations of advection fog formation are discussed with reference to observations of marine fog. A survey of candidate fog or cloud microphysics experiments which might be performed in the low gravity environment of a shuttle-type spacecraft in presented. Recommendations are given for relatively simple experiments which are relevent to fog modification problems.

Vertical profile of fog microphysics : a case study

Science.gov (United States)

Burnet, Frédéric; Brilouet, Pierre-Etienne; Mazoyer, Marie; Bourrianne, Thierry; Etcheberry, Jean-Michel; Gaillard, Brigitte; Legain, Dominique; Tzanos, Diane; Barrié, Joel; Barrau, Sébastien; Defoy, Stephan

2016-04-01

The occurrence and development of fogs result from the non-linear interaction of competing radiative, thermodynamic, microphysical and dynamical processes and the forecasting of their life cycle still remains a challenging issue. Several field campaigns have been carried out at the SIRTA observatory in the Paris suburb area (France). These experiments have shown that fog events exhibit large differences of the microphysical properties and various evolutions during their life cycle. To better understand relationships between the different processes and to validate numerical simulations it is necessary however to document the vertical profile of the fog microphysics. A CDP (Cloud Droplet Spectrometer) from DMT (Droplet Measurement Technology, Boulder, CO) has been modified to allow measurements of the droplet size distribution in fog layers with a tethered balloon. This instrumental set-up has been used during a field campaign during the winter 2013-214 in the Landes area in the South West of France. To validate the vertical profiles provided by the modified CDP, a mast was equipped with microphysical instruments at 2 altitude levels with an another CDP at 24 m and a Fog Monitor FM100 at 42 m. The instrumental set-up deployed during this campaign is presented. Data collected during a fog event that occurred during the night of 5-6 March 2014 are analysed. We show that microphysical properties such as droplet number concentration, LWC and mean droplet size, exhibit different time evolution during the fog life cycle depending on the altitude level. Droplet size distribution measurements are also investigated. They reveal sharp variations along the vertical close to the top of the fog layer. In addition it is shown that the shape of the size distributions at the top follows a time evolution typical of a quasi-adiabatic droplet growth.

Fog in the coastal region of southern Brazil: seasonal variations

Science.gov (United States)

Krusche, N.; Gomes, C.

2009-05-01

Fog forecasting, especially advection fog, is important because a large port is located at Rio Grande, 32° S and 52° W. Fogs discontinue the cargo transport and prevent entrance of ships in the port, causing great financial loss. Atmospheric and oceanographic conditions associated to fog formation are been investigated, especially those that happen during advection fog. The result of this characterization will facilitate the forecast using mesoscale numerical models. The research started with a climatology of fog in the region, in two locations which are 2° of latitude apart, with an average temperature difference of 3°C. The observation of fog is a standard record at conventional meteorological stations. Data from this study was obtained from the Meteorological Station of Rio Grande, which belongs to the Instituto Nacional de Meteorologia network, and from the Meteorological Station operated by the Division of Meteorology of Department of Airspace Control in Porto Alegre. The period of this study is from January 1990 to December 2005. The distribution of the monthly total of fog observations shows that they occur mainly between May and August, with maximum in June. In all seasons of the year the total number of fogs is greater than in Porto Alegre in Rio Grande. There was a decrease in the average annual number of fogs from the 90s to the last five years of research, which can be attributed to urbanization around the places of observation. It increases the temperature in the layers closer to the soil and decreases the available moisture, making the occurrence of radiation fog. Atmospheric and oceanographic conditions, prevalent during these occurrences, will be examined next. The another goal is to compare the data of advection fog in Rio Grande, obtained from images of the type ARGUS in Cassino beach, with those recorded by Meteorological Station. This work is partially financed by FINEP and CAPES.

Impact of fog processing on water soluble organic aerosols.

Science.gov (United States)

Tripathi, S. N.; Chakraborty, A.; Gupta, T.

2017-12-01

Fog is a natural meteorological phenomenon that occurs all around the world, and contains a substantial quantity of liquid water. Fog is generally seen as a natural cleansing agent but can also form secondary organic aerosols (SOA) via aqueous processing of ambient organics. Few field studies have reported elevated O/C ratio and SOA mass during or after fog events. However, mechanism behind aqueous SOA formation and its contribution to total organic aerosols (OA) still remains unclear. In this study we have tried to explore the impact of fog/aqueous processing on the characteristics of water soluble organic aerosols (WSOC), which to our knowledge has not been studied before. To assess this, both online (using HR-ToF-AMS) and offline (using a medium volume PM2.5 sampler and quartz filter) aerosol sampling were carried out at Kanpur, India from 15 December 2014 - 10 February 2015. Further, offline analysis of the aqueous extracts of the collected filters were carried out by AMS to characterize the water soluble OA (WSOA). Several (17) fog events occurred during the campaign and high concentrations of OA (151 ± 68 µg/m3) and WSOA (47 ± 19 µg/m3) were observed. WSOA/OA ratios were similar during fog (0.36 ± 0.14) and nofog (0.34 ± 0.15) periods. WSOA concentrations were also similar (slightly higher) during foggy (49 ± 18 µg/m3) and non-foggy periods (46 ± 20 µg/m3), in spite of fog scavenging. However, WSOA was more oxidized during foggy period (average O/C = 0.81) than non foggy periods (average O/C = 0.70). Like WSOA, OA was also more oxidized during foggy periods (average O/C = 0.64) than non foggy periods (average O/C = 0.53). During fog, WSOA to WIOA (water insoluble OA) ratios were higher (0.65 ± 0.16) compared to non foggy periods (0.56 ± 0.15). These observations clearly showed that WSOA become more dominant and processed during fog events, possibly due to the presence of fog droplets. This study highlights that fog processing of soluble organics

Crowd Sensing-Enabling Security Service Recommendation for Social Fog Computing Systems

Directory of Open Access Journals (Sweden)

Jun Wu

2017-07-01

Full Text Available Fog computing, shifting intelligence and resources from the remote cloud to edge networks, has the potential of providing low-latency for the communication from sensing data sources to users. For the objects from the Internet of Things (IoT to the cloud, it is a new trend that the objects establish social-like relationships with each other, which efficiently brings the benefits of developed sociality to a complex environment. As fog service become more sophisticated, it will become more convenient for fog users to share their own services, resources, and data via social networks. Meanwhile, the efficient social organization can enable more flexible, secure, and collaborative networking. Aforementioned advantages make the social network a potential architecture for fog computing systems. In this paper, we design an architecture for social fog computing, in which the services of fog are provisioned based on “friend” relationships. To the best of our knowledge, this is the first attempt at an organized fog computing system-based social model. Meanwhile, social networking enhances the complexity and security risks of fog computing services, creating difficulties of security service recommendations in social fog computing. To address this, we propose a novel crowd sensing-enabling security service provisioning method to recommend security services accurately in social fog computing systems. Simulation results show the feasibilities and efficiency of the crowd sensing-enabling security service recommendation method for social fog computing systems.

Crowd Sensing-Enabling Security Service Recommendation for Social Fog Computing Systems

Science.gov (United States)

Wu, Jun; Su, Zhou; Li, Jianhua

2017-01-01

Fog computing, shifting intelligence and resources from the remote cloud to edge networks, has the potential of providing low-latency for the communication from sensing data sources to users. For the objects from the Internet of Things (IoT) to the cloud, it is a new trend that the objects establish social-like relationships with each other, which efficiently brings the benefits of developed sociality to a complex environment. As fog service become more sophisticated, it will become more convenient for fog users to share their own services, resources, and data via social networks. Meanwhile, the efficient social organization can enable more flexible, secure, and collaborative networking. Aforementioned advantages make the social network a potential architecture for fog computing systems. In this paper, we design an architecture for social fog computing, in which the services of fog are provisioned based on “friend” relationships. To the best of our knowledge, this is the first attempt at an organized fog computing system-based social model. Meanwhile, social networking enhances the complexity and security risks of fog computing services, creating difficulties of security service recommendations in social fog computing. To address this, we propose a novel crowd sensing-enabling security service provisioning method to recommend security services accurately in social fog computing systems. Simulation results show the feasibilities and efficiency of the crowd sensing-enabling security service recommendation method for social fog computing systems. PMID:28758943

Prediction of Fog/Visibility over India using NWP Model

Indian Academy of Sciences (India)

54

fog which is driven by NWP model forecast of surface relative humidity and wind speed. The performance of NWP model forecast of visibility is found comparable to that from simple fog model driven by NWP forecast of relative humidity and wind speed. Keywords: Visibility, Fog, Insat-3D, METARS, NCUM, North India.

Lambda-lifting in Quadratic Time

DEFF Research Database (Denmark)

Danvy, O.; Schultz, U.P.

2004-01-01

-lifting transforms a block-structured program into a set of recursive equations, one for each local function in the source program. Each equation carries extra parameters to account for the free variables of the corresponding local function and of all its callees. It is the search for these extra parameters......Lambda-lifting is a program transformation that is used in compilers, partial evaluators, and program transformers. In this article, we show how to reduce its complexity from cubic time to quadratic time, and we present a flow-sensitive lambda-lifter that also works in quadratic time. Lambda...... that yields the cubic factor in the traditional formulation of lambda-lifting, which is due to Johnsson. This search is carried out by computing a transitive closure. To reduce the complexity of lambda-lifting, we partition the call graph of the source program into strongly connected components, based...

Light scattering from superfluid fog

International Nuclear Information System (INIS)

Kim, Heetae; Lemieux, P.-A.Pierre-Anthony; Durian, Douglas; Williams, G.A.Gary A.

2003-01-01

The dynamics of the droplets of superfluid 4 He fog created by an ultrasonic transducer are investigated using a laser scattering technique. Diffusing-wave spectroscopy probes the motion of the droplets, which is found to be ballistic for times shorter than a characteristic viscous time τ v =10 -5 s. The average relative velocity between the droplets is small compared to the velocity that the droplets are ejected from the surface into the fog, but increases proportionally to it

Pollution Levels in Fog at the Chilean Coast

Science.gov (United States)

Sträter, E.; Klemm, O.; Westbeld, A.

2010-07-01

During July and August 2008 fog water was collected for chemical analysis in Patache, at the coast of northern Chile, 60 km south of Iquique (20°49’S, 70°09’W). Advective fog events occur regularly at the cliff in the coastal range at about 800 m above MSL. People collect these types of fog water at some places along the coast with Large Fog Collectors (LFC) for domestic use and for watering field crops. So far, no chemical analysis of fog water was performed in Patache. Pure fogwater samples (38 samples from 8 fog events) were taken by using a passive Scientific Cylindrical Fog Collector. Major ions and trace metals were quantified. The analyses indicate very high ionic concentrations (mean 3500 µeq/l) and very low pH values (mean 3.3). The mean H+-concentration represents 16 % of the total ionic equivalent concentration. Sulfate is the anion exhibiting the highest concentrations. A mean value of 880 µeq/l was found, which accounts for 24 % of the total mean concentration. In contrast to sulfate, nitrate shows only a low percentage of 8.1 %. Further major ions are sodium (20%) and chloride (19 %), which are typical seasalt ions in coastal fog. High correlations between the measured ions suggest a causal link between concentration in the fog samples and the liquid water content (LWC) of the cloud. The higher the liquid water content the lower are the ionic concentrations. Enrichment factors with sodium as reference ion were calculated to identify potential emission sources contributing to the observed pollutant levels. We found that K+, Na+, Mg2+ and Cl- mainly result from seaspray. Sulfate, however, is enriched by a factor of 13. The measured trace elements are highly enriched by factors up to hundreds of thousands (Zn: 50, Ni: 1800, As: 2400, Cd: 3900, Fe: 100000, Cu: 96000, Pb: 250000). A cluster analysis supports the conclusion that sulfate and the trace elements originate from anthropogenic activities. The sulfate cannot primarily originate from

Problems, control, and treatment of fat, oil, and grease (FOG): a review.

Science.gov (United States)

Husain, Iman A F; Alkhatib, Ma'an Fahmi; Jammi, Mohamed Saedi; Mirghani, Mohamed E S; Bin Zainudin, Zaki; Hoda, Asif

2014-01-01

Presence of fat, oil, and grease (FOG) in wastewater is an ever-growing concern to municipalities and solid-waste facility operators. FOG enters the sewer system from restaurants, residences, and industrial food facilities. Its release into the sewer system results in a continuous build-up that causes eventual blockage of sewer pipes. Several researchers have investigated FOG deposition based on the local conditions of sewers and lifestyle. This paper attempts to review the physical and chemical characteristics of FOG, sources of FOG, and potential chemical and biological reactions of FOG. The effect of the aforementioned factors on the FOG-deposition mechanism is also discussed. Moreover, insight into the current control and treatment methods and potential reuse of FOG is highlighted. It is expected that this review would provide scientists and the concerned authorities a holistic view of the recent researches on FOG control, treatment, and reuse.

Fog Collection Pilot Project (FCPP) in the Eastern Escarpments of Eritrea

Science.gov (United States)

Gherezghiher, T.

2010-07-01

Eritrea is water scarce country that relies heavily on underground water reserve and more than 80% of the rural population does not have access to safe and clean drinking water. In the rural areas, shallow hand dug wells are the primary sources of water and in most cases their discharge rate is deteriorating due to the recurrent drought. Particularly, in the targeted project areas underground water reserve is hard to find due to the steep topography. However, in these parts of Eritrea one will find a sector of mountains, about 700 km long, where the wind transports moist air from the Red Sea forming fog on the highlands. The area of the FCPP is the region of Maakel, near the villages Nefasit and Arborobu. The overall objective of his FCPP was to provide supplementary water supply system from large fog collectors (LFCs) in order to increase access to safe and clean drinking water in the targeted Schools and surrounding villages. Communities and students were organized to participate in the implementation of the project. Forty LFCs were established in all the targeted areas in previously evaluated potential locations. The project was implemented by Vision Eritrea, a National NGO in partnership with the country's' Water Resource Department; Fog Quest a Canadian NGO and Water Foundation, a German NGO, who also funded the project. The FCPP focused on introducing a new innovative water harvesting technology which is a crucial element for the survival of the people in the mountainous escarpment of the country; and with prospect of locally owned solutions for a sustainable management of and access to natural resource. Preliminary evaluation of the project showed that there was a good production of fog water, with an average of 6-8 litters/m2/day on the low intensity of fog and from 12 -18 litters on the high fog intensity. A functional water committee was established and trained on water management and maintenance of the LFC. They also developed water bylaw by which the

UAV applications for thermodynamic profiling: Emphasis on ice fog research

Science.gov (United States)

Gultepe, Ismail; Heymsfield, Andrew J.; Fernando, Harindra J. S.; Hoch, Sebastian W.; Ware, Randolph

2016-04-01

Ice fog occurs often over the Arctic, cold climatic, and mountainous regions for about 30% of time where temperature (T) can go down to -10°C or below. Ice Nucleation (IN) and cooling processes play an important role by the controlling the intensity of ice fog conditions that affect aviation application, transportation, and local climate. Ice fog can also occur at T above -10°C but close to 0°C it occurs due to freezing of supercooled droplets that include an IN. To better document ice fog conditions, observations from the ice fog events of the Indirect and Semi-Direct Aerosol effects on Climate (ISDAC) project, Barrow, Alaska, Fog Remote Sensing And Modeling (FRAM) project Yellowknife, Northwest Territories, and the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) project, Heber City, Utah, were analyzed.. Measurements difficulties of small ice fog particles at cold temperatures and low-level flying restrictions prevent observations from aircraft within the surface boundary layer. However, unmanned Aerial Vehicles (UAVs) can be operated safely to measure IN number concentration, Relative Humidity with respect to ice (RHi), T, horizontal wind speed (Uh) and direction, and ice crystal spectra less than about 500 micron. Thermodynamic profiling by a Radiometrics Profiling Microwave Radiometer (PMWR) and Vaisala CL51 ceilometer was used to describe ice fog conditions in the vertical and its time development. In this presentation, ice fog characteristics and its thermodynamic environment will be presented using both ground-based and airborne platforms such as a UAV with new sensors. Some examples of measurements from the UAV for future research, and challenges related to both ice fog measurements and visibility parameterization will also be presented.

A field study of pollutant deposition in radiation fog

Energy Technology Data Exchange (ETDEWEB)

Waldman, J.M.; Jacob, D.J.; Munger, J.W.; Hoffman, M.R.

1986-04-01

Deposition during fog episodes can make a significant contribution to the overall flux of pollutants in certain ecosystems. Furthermore, when atmospheric stagnation prevents normal ventilation in a region, fog deposition may become the main route of pollutant removal. Fogs can consequently exert dominant control over pollutant levels in certain atmospheres. The southern San Joaquin Valley (SJV) of California is a region prone to wintertime episodes of atmospheric stagnation. These lead to elevated pollutant concentrations and/or dense, widespread fogs. Major oil-recovery operations plus widespread agricultural and livestock feeding activities are important sources of SO/sub 2/, NO/sub X/ and NH/sub 3/ in the valley. A multifaceted program of field monitoring was conducted in the SJV during the winter 1984-1985, focusing on aspects of pollutant scavenging and removal in the fog-laden atmosphere. Concentrations of major species were measured in gas, dry aerosol and fogwater phases. In addition, depositional fluxes were monitored by surrogate-surface methods. These measurements were employed to directly assess the magnitude of removal enhancement by fog.

Fog detection for interstate and state highways.

Science.gov (United States)

2012-12-01

Fog is a common and recurrent phenomenon in West Virginia which is the cause of nearly 1.3% of all fatal crashes : occurring all over the state. All three types of fog are common in the state which results in lack visibility, limited : contrast, dist...

CT fogging effect with ischemic cerebral infarcts

International Nuclear Information System (INIS)

Becker, H.; Desch, H.; Hacker, H.; Pencz, A.; Frankfurt Univ.

1979-01-01

Systematic CT studies on ten patients with persistent ischemic cerebral infarct revealed a constant phenomenon, the fogging effect. The hypodense infarct at the beginning will be isodense, or close to isodense, on the plain CT during the second or third week and at a later stage will be hypodense again. The fogging infarcted area shows homogeneous intensive contrast enhancement. Knowledge of the fogging effect is important for correct interpretation of the CT image and the indication for contrast medium CT. CT without contrast medium may lead to misinterpretation during the second and third week after the onset of cerebral infarction. (orig.) [de

CT fogging effect with ischemic cerebral infarcts

Energy Technology Data Exchange (ETDEWEB)

Becker, H; Desch, H; Hacker, H; Pencz, A [Frankfurt Univ. (Germany, F.R.). Abt. fuer Neurologie; Frankfurt Univ. (Germany, F.R.). Abt. fuer Neuroradiologie)

1979-01-01

Systematic CT studies on ten patients with persistent ischemic cerebral infarct revealed a constant phenomenon, the fogging effect. The hypodense infarct at the beginning will be isodense, or close to isodense, on the plain CT during the second or third week and at a later stage will be hypodense again. The fogging infarcted area shows homogeneous intensive contrast enhancement. Knowledge of the fogging effect is important for correct interpretation of the CT image and the indication for contrast medium CT. CT without contrast medium may lead to misinterpretation during the second and third week after the onset of cerebral infarction.

Hierarchical Surface Architecture of Plants as an Inspiration for Biomimetic Fog Collectors.

Science.gov (United States)

Azad, M A K; Barthlott, W; Koch, K

2015-12-08

Fog collectors can enable us to alleviate the water crisis in certain arid regions of the world. A continuous fog-collection cycle consisting of a persistent capture of fog droplets and their fast transport to the target is a prerequisite for developing an efficient fog collector. In regard to this topic, a biological superior design has been found in the hierarchical surface architecture of barley (Hordeum vulgare) awns. We demonstrate here the highly wettable (advancing contact angle 16° ± 2.7 and receding contact angle 9° ± 2.6) barbed (barb = conical structure) awn as a model to develop optimized fog collectors with a high fog-capturing capability, an effective water transport, and above all an efficient fog collection. We compare the fog-collection efficiency of the model sample with other plant samples naturally grown in foggy habitats that are supposed to be very efficient fog collectors. The model sample, consisting of dry hydrophilized awns (DH awns), is found to be about twice as efficient (fog-collection rate 563.7 ± 23.2 μg/cm(2) over 10 min) as any other samples investigated under controlled experimental conditions. Finally, a design based on the hierarchical surface architecture of the model sample is proposed for the development of optimized biomimetic fog collectors.

Fog-basking behaviour and water collection efficiency in Namib Desert Darkling beetles.

Science.gov (United States)

Nørgaard, Thomas; Dacke, Marie

2010-07-16

In the Namib Desert fog represents an alternative water source. This is utilised by Darkling beetles (Tenebrionidae) that employ different strategies for obtaining the fog water. Some dig trenches in the sand, while others use their own bodies as fog collectors assuming a characteristic fog-basking stance. Two beetle species from the genus Onymacris have been observed to fog-bask on the ridges of the sand dunes. These beetles all have smooth elytra surfaces, while another species with elytra covered in bumps is reported to have specialised adaptations facilitating water capture by fog-basking. To resolve if these other beetles also fog-bask, and if an elytra covered in bumps is a more efficient fog water collector than a smooth one, we examined four Namib Desert beetles; the smooth Onymacris unguicularis and O. laeviceps and the bumpy Stenocara gracilipes and Physasterna cribripes. Here we describe the beetles' fog-basking behaviour, the details of their elytra structures, and determine how efficient their dorsal surface areas are at harvesting water from fog. The beetles differ greatly in size. The largest P. cribripes has a dorsal surface area that is 1.39, 1.56, and 2.52 times larger than O. unguicularis, O. laeviceps, and S. gracilipes, respectively. In accordance with earlier reports, we found that the second largest O. unguicularis is the only one of the four beetles that assumes the head standing fog-basking behaviour, and that fog is necessary to trigger this behaviour. No differences were seen in the absolute amounts of fog water collected on the dorsal surface areas of the different beetles. However, data corrected according to the sizes of the beetles revealed differences. The better fog water harvesters were S. gracilipes and O. unguicularis while the large P. cribripes was the poorest. Examination of the elytra microstructures showed clear structural differences, but the elytra of all beetles were found to be completely hydrophobic. The differences in

COSMO-PAFOG: Three-dimensional fog forecasting with the high-resolution COSMO-model

Science.gov (United States)

Hacker, Maike; Bott, Andreas

2017-04-01

The presence of fog can have critical impact on shipping, aviation and road traffic increasing the risk of serious accidents. Besides these negative impacts of fog, in arid regions fog is explored as a supplementary source of water for human settlements. Thus the improvement of fog forecasts holds immense operational value. The aim of this study is the development of an efficient three-dimensional numerical fog forecast model based on a mesoscale weather prediction model for the application in the Namib region. The microphysical parametrization of the one-dimensional fog forecast model PAFOG (PArameterized FOG) is implemented in the three-dimensional nonhydrostatic mesoscale weather prediction model COSMO (COnsortium for Small-scale MOdeling) developed and maintained by the German Meteorological Service. Cloud water droplets are introduced in COSMO as prognostic variables, thus allowing a detailed description of droplet sedimentation. Furthermore, a visibility parametrization depending on the liquid water content and the droplet number concentration is implemented. The resulting fog forecast model COSMO-PAFOG is run with kilometer-scale horizontal resolution. In vertical direction, we use logarithmically equidistant layers with 45 of 80 layers in total located below 2000 m. Model results are compared to satellite observations and synoptic observations of the German Meteorological Service for a domain in the west of Germany, before the model is adapted to the geographical and climatological conditions in the Namib desert. COSMO-PAFOG is able to represent the horizontal structure of fog patches reasonably well. Especially small fog patches typical of radiation fog can be simulated in agreement with observations. Ground observations of temperature are also reproduced. Simulations without the PAFOG microphysics yield unrealistically high liquid water contents. This in turn reduces the radiative cooling of the ground, thus inhibiting nocturnal temperature decrease. The

Fog-basking behaviour and water collection efficiency in Namib Desert Darkling beetles

Directory of Open Access Journals (Sweden)

Dacke Marie

2010-07-01

Full Text Available Abstract Background In the Namib Desert fog represents an alternative water source. This is utilised by Darkling beetles (Tenebrionidae that employ different strategies for obtaining the fog water. Some dig trenches in the sand, while others use their own bodies as fog collectors assuming a characteristic fog-basking stance. Two beetle species from the genus Onymacris have been observed to fog-bask on the ridges of the sand dunes. These beetles all have smooth elytra surfaces, while another species with elytra covered in bumps is reported to have specialised adaptations facilitating water capture by fog-basking. To resolve if these other beetles also fog-bask, and if an elytra covered in bumps is a more efficient fog water collector than a smooth one, we examined four Namib Desert beetles; the smooth Onymacris unguicularis and O. laeviceps and the bumpy Stenocara gracilipes and Physasterna cribripes. Here we describe the beetles' fog-basking behaviour, the details of their elytra structures, and determine how efficient their dorsal surface areas are at harvesting water from fog. Results The beetles differ greatly in size. The largest P. cribripes has a dorsal surface area that is 1.39, 1.56, and 2.52 times larger than O. unguicularis, O. laeviceps, and S. gracilipes, respectively. In accordance with earlier reports, we found that the second largest O. unguicularis is the only one of the four beetles that assumes the head standing fog-basking behaviour, and that fog is necessary to trigger this behaviour. No differences were seen in the absolute amounts of fog water collected on the dorsal surface areas of the different beetles. However, data corrected according to the sizes of the beetles revealed differences. The better fog water harvesters were S. gracilipes and O. unguicularis while the large P. cribripes was the poorest. Examination of the elytra microstructures showed clear structural differences, but the elytra of all beetles were found to

[Microphysics of atmospheric aerosols during winter haze/fog events in Nanjing].

Science.gov (United States)

Yang, Jun; Niu, Zhong-qing; Shi, Chun-e; Liu, Duan-yang; Li, Zi-hua

2010-07-01

Intensive field observations of fog/haze events, including simultaneous measurements of aerosol particle and fog droplet size distributions, were conducted in Nanjing in November, 2007. Four weather conditions (fog, mist, wet haze and haze) were distinguished based on visibility and liquid water content firstly. Then, the microphysical characteristics of coarse and fine particles in each condition were investigated. The results showed the dominant sequence of the four weather conditions was hazemist-->wet haze-->fog-->, wet haze-->misthaze. The lasting time of pre-fog wet haze was longer than that of post-fog wet haze. The number, surface area and volume concentration of coarse particles with diameter larger than 2.0 micron in fog were much higher than those in the other three conditions, and the smallest concentrations were observed in haze. The size distributions of surface area and volume concentration exhibited multi-peak in fog droplets, while it showed single peak for coarse particles in haze, mist and wet haze. For the fine particles with diameter larger than 0.010 microm, the spectral shapes of surface area concentration are similar in fog (mist) and wet haze (haze) condition. The dominant size ranges of fine particle number concentration were in 0.04-0.13 microm and 0.02-0.14 microm for fog and wet haze, separately. The same dominant size ranges located in 0.02-0.06 microm for both mist and haze. During the transition processes from haze, mist and wet haze to fog, the concentration of smaller particles (less than 0.060-0.090 microm) reduced and vice versa for the corresponding larger particles. Temporal variation of aerosol number concentration correlated well with the root mean diameters negatively during the observation period. The number concentration of aerosol was the lowest and the mean diameter was the largest in fog periods.

Light scattering from superfluid fog

Energy Technology Data Exchange (ETDEWEB)

Kim, Heetae; Lemieux, P.-A.Pierre-Anthony; Durian, Douglas; Williams, G.A.Gary A

2003-05-01

The dynamics of the droplets of superfluid {sup 4}He fog created by an ultrasonic transducer are investigated using a laser scattering technique. Diffusing-wave spectroscopy probes the motion of the droplets, which is found to be ballistic for times shorter than a characteristic viscous time {tau}{sub v}=10{sup -5} s. The average relative velocity between the droplets is small compared to the velocity that the droplets are ejected from the surface into the fog, but increases proportionally to it.

Coastal Fog As a System: Defining an Interdisciplinary Research Agenda (Invited)

Science.gov (United States)

Weathers, K. C.

2013-12-01

Fog is a graphic and charismatic phenomenon that is commonplace in coastal geographies around the globe. Some of the first concerns about fog and human health arose over 50 years ago in foggy cities around the world, such as London and Los Angeles, where thousands of excess deaths have been attributed to the presence of acidic fog particles. Further, the mere presence of fog also results in airplane, ship, and automobile traffic delays and accidents, especially in coastal areas. In many Pacific coastal systems, fog is the primary--sometimes the only--source of water, it is a fundamental moderator of local and regional climate, and it influences productivity of near-coast ecosystems. In recent years fog has been identified as a vector for limiting nutrients (e.g., nitrogen and phosphorus), pollutants (e.g., mercury), and microbes (including human pathogens), all of whose origin is thought to be biologically controlled in the ocean. Researchers have also started inquiring into the importance of fog in modulating weather as well as local, regional and, global climate dynamics. However, from its formation in marine systems to deposition in terrestrial systems, understanding the fog system is an intellectual and interdisciplinary challenge that, to date, has gone unmet. This is in part because the fog system is complex: it involves feedbacks and coupling between physical, chemical, and biological systems in the ocean, atmosphere, and near-coast terrestrial systems. In addition, its formation is the result of global processes, yet its distribution as well as its impacts are local, and extremely spatially and temporally heterogeneous within and across landscapes. Here we describe a systems approach and framework for understanding the controls on fog formation as well as feedbacks to its formation, dissipation, distribution, flows, and stocks or pools. In addition, an interdisciplinary research agenda for coastal fog as a system will be described based on the outcome of a

The Innovative Design and Prototype Verification of Wheelchair with One Degree of Freedom to Perform Lifting and Standing Functions

Science.gov (United States)

Hsieh, Long-Chang; Chen, Tzu-Hsia

2017-12-01

Traditionally, the mechanism of wheelchair with lifting and standing functions has 2 degrees of freedom, and used 2 power sources to perform these 2 motion function. The purpose of this paper is to invent new wheelchair with 1 degree of freedom to perform these 2 motion functions. Hence, we can use only 1 power source to drive the mechanism to achieve lifting and standing motion functions. The new design has the advantages of simple operation, more stability, and more safety. For traditional standing wheelchair, its’ centre of gravity moves forward when standing up and it needs 2 auxiliary wheels to prevent dumping. In this paper, by using the checklist method of Osborn, the wheelchair with 1 DOF is invented to perform lifting and standing functions. The centre of gravity of this new wheelchair after standing up still located between the front and rear wheels, no auxiliary wheels needed. Finally, the prototype is manufactured to verify the theoretical results.

Diurnal temperature asymmetries and fog at Churchill, Manitoba

Science.gov (United States)

Gough, William A.; He, Dianze

2015-07-01

A variety of methods are available to calculate daily mean temperature. We explore how the difference between two commonly used methods provides insight into the local climate of Churchill, Manitoba. In particular, we found that these differences related closely to seasonal fog. A strong statistically significant correlation was found between the fog frequency (hours per day) and the diurnal temperature asymmetries of the surface temperature using the difference between the min/max and 24-h methods of daily temperature calculation. The relationship was particularly strong for winter, spring and summer. Autumn appears to experience the joint effect of fog formation and the radiative effect of snow cover. The results of this study suggests that subtle variations of diurnality of temperature, as measured in the difference of the two mean temperature methods of calculation, may be used as a proxy for fog detection in the Hudson Bay region. These results also provide a cautionary note for the spatial analysis of mean temperatures using data derived from the two different methods particularly in areas that are fog prone.

Alternative Agents to Prevent Fogging in Head and Neck Endoscopy

Directory of Open Access Journals (Sweden)

Patorn Piromchai

2011-01-01

Full Text Available Background The essential factor for diagnosis and treatment of diseases in head and neck endoscopy is the visibility of the image. An anti-fogging agent can reduce this problem by minimizing surface tension to prevent the condensation of water in the form of small droplets on a surface. There is no report on the use of hibiscrub ® or baby shampoo to reduce fogging in the literature. The objective of this study was to compare the efficacy between commercial anti-fogging agent, hibiscrub ® and baby shampoo to reduce fogging for the use in head and neck endoscopy. Methods The study was conducted at the Department of Otorhinolaryngology, Faculty of Medicine, Khon Kaen University in August 2010. Commercial anti-fogging agent, baby shampoo and hibiscrub ® were applied on rigid endoscope lens before putting them into a mist generator. The images were taken at baseline, 15 seconds, 30 seconds and 1 minute. The images' identifiers were removed before they were sent to two evaluators. A visual analogue scale (VAS was used to rate the image quality from 0 to 10. Results The difference in mean VAS score between anti-fogging agent, baby shampoo and hibiscrub ® versus no agent were 5.46, 4.45 and 2.1 respectively. The commercial anti-fogging agent and baby shampoo had most protective benefit and performed significantly better than no agent ( P < 0.05. Conclusions Baby shampoo is an effective agent to prevent fogging during head and neck endoscopy and compares favourably with commercial anti-fogging agent.

Pesticide occurrence and distribution in fog collected near Monterey, California

Energy Technology Data Exchange (ETDEWEB)

Schomburg, C.J.; Glotfelty, D.E. (Department of Agriculture, Beltsville, MD (USA)); Seiber, J.N. (Univ. of California, Davis (USA))

1991-01-01

The authors analyzed pesticides in air and fog in several fog events sampled near Monterey, CA, to determine whether the uptake of pesticides in advected oceanic fog was different from uptake in fog forming under stagnant inversion conditions in California's Central Valley in the winter. Data for several pesticides common to both ares showed that the pesticide content and distribution were remarkable similar in the two locations. The conversion of organophosphorus insecticides to their corresponding oxons, and aqueous-phase enrichment factors, were also very similar. Evidence is presented to support the hypothesis that enhanced pesticide concentration in fogwater is caused by strongly sorptive nonfilterable particles and colloids in the fog liquid that are derived from atmospheric particles.

Numerical simulation of radiation fog in complex terrain

Science.gov (United States)

Zhang, X.; Musson-Genon, L.; Carissimo, B.; Dupont, E.

2009-09-01

The interest for micro-scale modeling of the atmosphere is growing for environmental applications related, for example, to energy production, transport and urban development. The turbulence in the stable layers where pollutant dispersion is low and can lead to strong pollution events. This could be further complicated by the presence of clouds or fog and is specifically difficult in urban or industrial area due to the presence of buildings. In this context, radiation fog formation and dissipation over complex terrain were therefore investigated with a state-of-the-art model. This study is divided into two phases. The first phase is a pilot stage, which consist of employing a database from the ParisFog campaign which took place in the south of Paris during winter 2006-07 to assess the ability of the cloud model to reproduce the detailed structure of radiation fog. The second phase use the validated model for the study of influence of complex terrain on fog evolution. Special attention is given to the detailed and complete simulations and validation technique used is to compare the simulated results using the 3D cloud model of computational fluid dynamical software Code_Saturne with one of the best collected in situ data during the ParisFog campaign. Several dynamical, microphysical parameterizations and simulation conditions have been described. The resulting 3D cloud model runs at a horizontal resolution of 30 m and a vertical resolution comparable to the 1D model. First results look very promising and are able to reproduce the spatial distribution of fog. The analysis of the behavior of the different parameterized physical processes suggests that the subtle balance between the various processes is achieved.

Fog deposition to a Tillandsia carpet in the Atacama Desert

Science.gov (United States)

Westbeld, A.; Klemm, O.; Grießbaum, F.; Sträter, E.; Larrain, H.; Osses, P.; Cereceda, P.

2009-09-01

In the Atacama Desert, one of the driest places on earth, fog deposition plays an important role for the water balance and for the survival of vulnerable ecosystems. The eddy covariance method, previously applied for the quantification of fog deposition to forests in various parts of the world, was used for the first time to measure deposition of fog water to a desert. In this exploratory study we estimate the amount of water available for the ecosystem by deposition and determine the relevant processes driving fog deposition. This is especially important for the species Tillandsia landbecki living in coastal Atacama at the limit of plant existence with fog and dew being the only sources of water. Between 31 July and 19 August 2008 approximately 2.5 L m-2 of water were made available through deposition. Whole-year deposition was estimated as 25 L m-2. Turbulent upward fluxes occurred several times during the evenings and are explained by the formation of radiation fog. In connection with that, underestimates of the deposition are assumed. More detailed studies covering various seasons and all parameters and fluxes contributing to the local energy balance are suggested. This will help to further develop understanding about the processes of (i) deposition of water to the desert, and (ii) intensification of advection fog through additional formation of radiation fog.

Fog deposition to a Tillandsia carpet in the Atacama Desert

Energy Technology Data Exchange (ETDEWEB)

Westbeld, A.; Klemm, O.; Griessbaum, F.; Straeter, E. [Muenster Univ. (Germany). Inst. of Landscape Ecology; Larrain, H. [Pontificia Univ. Catolica de Chile (Chile). Atacama Desert Center ADC; Univ. Bolivariana, Iquique (Chile); Osses, P.; Cereceda, P. [Pontificia Univ. Catolica de Chile, Santiago de Chile (Chile). Inst. of Geography

2009-07-01

In the Atacama Desert, one of the driest places on earth, fog deposition plays an important role for the water balance and for the survival of vulnerable ecosystems. The eddy covariance method, previously applied for the quantification of fog deposition to forests in various parts of the world, was used for the first time to measure deposition of fog water to a desert. In this exploratory study we estimate the amount of water available for the ecosystem by deposition and determine the relevant processes driving fog deposition. This is especially important for the species Tillandsia landbecki living in coastal Atacama at the limit of plant existence with fog and dew being the only sources of water. Between 31 July and 19 August 2008 approximately 2.5 L m{sup -2} of water were made available through deposition. Whole-year deposition was estimated as 25 L m{sup -2}. Turbulent upward fluxes occurred several times during the evenings and are explained by the formation of radiation fog. In connection with that, underestimates of the deposition are assumed. More detailed studies covering various seasons and all parameters and fluxes contributing to the local energy balance are suggested. This will help to further develop understanding about the processes of (i) deposition of water to the desert, and (ii) intensification of advection fog through additional formation of radiation fog. (orig.)

Fog deposition to a Tillandsia carpet in the Atacama Desert

Directory of Open Access Journals (Sweden)

P. Osses

2009-09-01

Full Text Available In the Atacama Desert, one of the driest places on earth, fog deposition plays an important role for the water balance and for the survival of vulnerable ecosystems. The eddy covariance method, previously applied for the quantification of fog deposition to forests in various parts of the world, was used for the first time to measure deposition of fog water to a desert. In this exploratory study we estimate the amount of water available for the ecosystem by deposition and determine the relevant processes driving fog deposition. This is especially important for the species Tillandsia landbecki living in coastal Atacama at the limit of plant existence with fog and dew being the only sources of water. Between 31 July and 19 August 2008 approximately 2.5 L m−2 of water were made available through deposition. Whole-year deposition was estimated as 25 L m−2. Turbulent upward fluxes occurred several times during the evenings and are explained by the formation of radiation fog. In connection with that, underestimates of the deposition are assumed. More detailed studies covering various seasons and all parameters and fluxes contributing to the local energy balance are suggested. This will help to further develop understanding about the processes of (i deposition of water to the desert, and (ii intensification of advection fog through additional formation of radiation fog.

Optimal design of permeable fiber network structures for fog harvesting.

Science.gov (United States)

Park, Kyoo-Chul; Chhatre, Shreerang S; Srinivasan, Siddarth; Cohen, Robert E; McKinley, Gareth H

2013-10-29

Fog represents a large untapped source of potable water, especially in arid climates. Numerous plants and animals use textural and chemical features on their surfaces to harvest this precious resource. In this work, we investigate the influence of the surface wettability characteristics, length scale, and weave density on the fog-harvesting capability of woven meshes. We develop a combined hydrodynamic and surface wettability model to predict the overall fog-collection efficiency of the meshes and cast the findings in the form of a design chart. Two limiting surface wettability constraints govern the re-entrainment of collected droplets and clogging of mesh openings. Appropriate tuning of the wetting characteristics of the surfaces, reducing the wire radii, and optimizing the wire spacing all lead to more efficient fog collection. We use a family of coated meshes with a directed stream of fog droplets to simulate a natural foggy environment and demonstrate a five-fold enhancement in the fog-collecting efficiency of a conventional polyolefin mesh. The design rules developed in this work can be applied to select a mesh surface with optimal topography and wetting characteristics to harvest enhanced water fluxes over a wide range of natural convected fog environments.

Fog water chemistry in the Namib desert, Namibia

Science.gov (United States)

Eckardt, Frank D.; Schemenauer, Robert S.

This study documents the ion concentrations and ion enrichment relative to sea water, in Namib Desert fog water, with the purpose of establishing its suitability for future fogwater collection schemes, while also examining claims that Namib Desert fog water carries exceptionally high concentrations of sulphate, which may be responsible for the formation of gypsum deposits in the desert. The work suggests that Namibian fog water is at least as clean as has been reported from other coastal deserts in South America and Arabia, and provides a source of very clean water for the coastal desert region of south-western Africa. It does not appear that fog is an efficient sulphur source for the formation of the gypsum deposits, unless rare events with high concentrations of marine sulphur compounds occur.

The effect of radioactive aerosols on fog formation

International Nuclear Information System (INIS)

Ali, G.; Khan, E.U.; Ali, N.; Khan, H.A.; Waheed, A.

2011-01-01

This research study has been carried out to explore the dependence of fog formation on radioactive aerosols. The aerosols containing radioactive nuclides are called radioactive aerosols. A large number of radioactive nuclides are present in the atmosphere among which the two most important nuclides, 7Be and 210Pb are considered here in this study. Results for Activity Concentrations of these radio-nuclides in air samples in clear and foggy conditions were comparatively analyzed. About 19% increase in Activity concentration for 210Pb and about 23% increase in Activity Concentration for 7Be was recorded during fog as compared to clear conditions. This increase in Activity Concentration during fog indicates that the presence of aerosols laden with these radio-nuclides is also one of the so many factors responsible for fog formation

The LXCXE Retinoblastoma Protein-Binding Motif of FOG-2 Regulates Adipogenesis.

Science.gov (United States)

Goupille, Olivier; Penglong, Tipparat; Kadri, Zahra; Granger-Locatelli, Marine; Denis, Raphaël; Luquet, Serge; Badoual, Cécile; Fucharoen, Suthat; Maouche-Chrétien, Leila; Leboulch, Philippe; Chrétien, Stany

2017-12-19

GATA transcription factors and their FOG cofactors play a key role in tissue-specific development and differentiation, from worms to humans. Mammals have six GATA and two FOG factors. We recently demonstrated that interactions between retinoblastoma protein (pRb) and GATA-1 are crucial for erythroid proliferation and differentiation. We show here that the LXCXE pRb-binding site of FOG-2 is involved in adipogenesis. Unlike GATA-1, which inhibits cell division, FOG-2 promotes proliferation. Mice with a knockin of a Fog2 gene bearing a mutated LXCXE pRb-binding site are resistant to obesity and display higher rates of white-to-brown fat conversion. Thus, each component of the GATA/FOG complex (GATA-1 and FOG-2) is involved in pRb/E2F regulation, but these molecules have markedly different roles in the control of tissue homeostasis. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Demonstration of measuring sea fog with an SNSPD-based Lidar system.

Science.gov (United States)

Zhu, Jiang; Chen, Yajun; Zhang, Labao; Jia, Xiaoqing; Feng, Zhijun; Wu, Ganhua; Yan, Xiachao; Zhai, Jiquan; Wu, Yang; Chen, Qi; Zhou, Xiaoying; Wang, Zhizhong; Zhang, Chi; Kang, Lin; Chen, Jian; Wu, Peiheng

2017-11-08

The monitor of sea fogs become more important with the rapid development of marine activities. Remote sensing through laser is an effective tool for monitoring sea fogs, but still challengeable for large distance. We demonstrated a Long-distance Lidar for sea fog with superconducting nanowire single-photon detector (SNSPD), which extended the ranging area to a 180-km diameter area. The system, which was verified by using a benchmark distance measurement of a known island, is applied to the Mie scattering weather prediction Lidar system. The fog echo signal distribution in the range of 42.3∼63.5 km and 53.2∼74.2 km was obtained by the Lidar system. Then the fog concentration and the velocity of the fog were deduced from the distribution, which is consistent with the weather prediction. The height of the sea fog is about two hundred meter while the visibility at this height is about 90 km due to the Earth's radius of curvature. Therefore, the capability of this SNSPD-based Lidar was close to the theoretical limit for sea fog measurements for extremely high signal-to-noise ratio of SNSPD.

Integration of Local Observations into the One Dimensional Fog Model PAFOG

Science.gov (United States)

Thoma, Christina; Schneider, Werner; Masbou, Matthieu; Bott, Andreas

2012-05-01

The numerical prediction of fog requires a very high vertical resolution of the atmosphere. Owing to a prohibitive computational effort of high resolution three dimensional models, operational fog forecast is usually done by means of one dimensional fog models. An important condition for a successful fog forecast with one dimensional models consists of the proper integration of observational data into the numerical simulations. The goal of the present study is to introduce new methods for the consideration of these data in the one dimensional radiation fog model PAFOG. First, it will be shown how PAFOG may be initialized with observed visibilities. Second, a nudging scheme will be presented for the inclusion of measured temperature and humidity profiles in the PAFOG simulations. The new features of PAFOG have been tested by comparing the model results with observations of the German Meteorological Service. A case study will be presented that reveals the importance of including local observations in the model calculations. Numerical results obtained with the modified PAFOG model show a distinct improvement of fog forecasts regarding the times of fog formation, dissipation as well as the vertical extent of the investigated fog events. However, model results also reveal that a further improvement of PAFOG might be possible if several empirical model parameters are optimized. This tuning can only be realized by comprehensive comparisons of model simulations with corresponding fog observations.

International evolution of fat, oil and grease (FOG) waste management - A review

OpenAIRE

Wallace, Thomas; Gibbons, David; O'Dwyer, Michael; Curran, Thomas P.

2017-01-01

In recent years, issues relating to fat, oil and grease (FOG) in sewer systems have intensified. In the media, sewer blockages caused by FOG waste deposits, commonly referred to as 'fatbergs', are becoming a reminder of the problems that FOG waste can cause when left untreated. These FOG blockages lead to sanitary sewer overflows, property flooding and contamination of water bodies with sewage. Despite these financial and environmentally detrimental effects, a homogenous FOG waste management ...

Maximum Acceptable Weight of Lift reflects peak lumbosacral extension moments in a Functional Capacity Evaluation test using free style, stoop, and squat lifting

NARCIS (Netherlands)

Kuijer, P.P.F.M.; van Oostrom, S.H.; Duijzer, K.; van Dieen, J.H.

2012-01-01

It is unclear whether the maximum acceptable weight of lift (MAWL), a common psychophysical method, reflects joint kinetics when different lifting techniques are employed. In a within-participants study (n = 12), participants performed three lifting techniques - free style, stoop and squat lifting

Maximum acceptable weight of lift reflects peak lumbosacral extension moments in a functional capacity evaluation test using free style, stoop and squat lifting

NARCIS (Netherlands)

Kuijer, P. P. F. M.; van Oostrom, S. H.; Duijzer, K.; van Dieën, J. H.

2012-01-01

It is unclear whether the maximum acceptable weight of lift (MAWL), a common psychophysical method, reflects joint kinetics when different lifting techniques are employed. In a within-participants study (n = 12), participants performed three lifting techniques - free style, stoop and squat lifting

Gene conversion and DNA sequence polymorphism in the sex-determination gene fog-2 and its paralog ftr-1 in Caenorhabditis elegans.

Science.gov (United States)

Rane, Hallie S; Smith, Jessica M; Bergthorsson, Ulfar; Katju, Vaishali

2010-07-01

Gene conversion, a form of concerted evolution, bears enormous potential to shape the trajectory of sequence and functional divergence of gene paralogs subsequent to duplication events. fog-2, a sex-determination gene unique to Caenorhabditis elegans and implicated in the origin of hermaphroditism in this species, resulted from the duplication of ftr-1, an upstream gene of unknown function. Synonymous sequence divergence in regions of fog-2 and ftr-1 (excluding recent gene conversion tracts) suggests that the duplication occurred 46 million generations ago. Gene conversion between fog-2 and ftr-1 was previously discovered in experimental fog-2 knockout lines of C. elegans, whereby hermaphroditism was restored in mutant obligately outcrossing male-female populations. We analyzed DNA-sequence variation in fog-2 and ftr-1 within 40 isolates of C. elegans from diverse geographic locations in order to evaluate the contribution of gene conversion to genetic variation in the two gene paralogs. The analysis shows that gene conversion contributes significantly to DNA-sequence diversity in fog-2 and ftr-1 (22% and 34%, respectively) and may have the potential to alter sexual phenotypes in natural populations. A radical amino acid change in a conserved region of the F-box domain of fog-2 was found in natural isolates of C. elegans with significantly lower fecundity. We hypothesize that the lowered fecundity is due to reduced masculinization and less sperm production and that amino acid replacement substitutions and gene conversion in fog-2 may contribute significantly to variation in the degree of inbreeding and outcrossing in natural populations.

Non-human primate FOG develops with advanced parkinsonism induced by MPTP Treatment.

Science.gov (United States)

Revuelta, Gonzalo J; Uthayathas, Subramaniam; Wahlquist, Amy E; Factor, Stewart A; Papa, Stella M

2012-10-01

Freezing of gait (FOG) is a debilitating feature of Parkinson's disease (PD) and other forms of parkinsonism. The anatomical or pathophysiological correlates are poorly understood largely due to the lack of a well-established animal model. Here we studied whether FOG is reproduced in the non-human primate (NHP) model of PD. 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated monkeys (Genus Macaca, n=29) were examined for the development of FOG, and the leg movements were recorded with accelerometry. The relationships between developing FOG and the animals' characteristics, the MPTP treatments, and the modeled outcomes were determined. In parkinsonian monkeys FOG developed frequently (48%) manifesting similar characteristics to those seen in PD patients. In addition, FOG episodes in the monkey were accompanied by leg trembling with the typical duration (2-10s) and frequency (~7 Hz). The development of NHP FOG was significantly associated with the severity of parkinsonism, as shown by high motor disability scores (≥ 20) and levodopa-induced dyskinesia scores (p=0.01 and p=0.04, respectively). Differences in demographics and MPTP treatments (doses, treatment duration, etc.) had no influence on NHP FOG occurrence, with the exception of gender that showed FOG predominance in males (p=0.03). The unique features of FOG in PD can be replicated in severely parkinsonian macaques, and this represents the first description of a FOG animal model. Published by Elsevier Inc.

Fog seal guidelines.

Science.gov (United States)

2003-10-01

Fog seals are a method of adding asphalt to an existing pavement surface to improve sealing or waterproofing, prevent further stone loss by holding aggregate in place, or simply improve the surface appearance. However, inappropriate use can result in...

Fog-basking behaviour and water collection efficiency in Namib Desert Darkling beetles

OpenAIRE

Dacke Marie; Nørgaard Thomas

2010-01-01

Abstract Background In the Namib Desert fog represents an alternative water source. This is utilised by Darkling beetles (Tenebrionidae) that employ different strategies for obtaining the fog water. Some dig trenches in the sand, while others use their own bodies as fog collectors assuming a characteristic fog-basking stance. Two beetle species from the genus Onymacris have been observed to fog-bask on the ridges of the sand dunes. These beetles all have smooth elytra surfaces, while another ...

The effect of fog on radionuclide deposition velocities

International Nuclear Information System (INIS)

Gibb, R.; Carson, P.; Thompson, W.

1997-01-01

Current nuclear power station release models do not evaluate deposition under foggy atmospheric conditions. Deposition velocities and scavenging coefficients of radioactive particles entrained in fog are presented for the Point Lepreau area of the Bay of Fundy coast. It is recommended to calculate deposition based on fog deposition velocities. The deposition velocities can be calculated from common meteorological data. The range of deposition velocities is approximately 1 - 100 cm/s. Fog deposition is surface roughness dependent with forests having larger deposition and deposition velocities than soil or grasses. (author)

Chemistry of fog: Factors regulating its composition

Energy Technology Data Exchange (ETDEWEB)

Sigg, L.; Stumm, W.; Zobrist, J.; Zuercher, F.

1987-05-01

Fog droplets acquire their composition, in principle, by similar mechanisms as cloudwater droplets. The solute concentrations of fogwater (H/sup +/, NH/sub 4/+, NO/sub 3//sup -/, SO/sub 4//sup 2-/, Cl/sup -/, organic acids, and trace metals) are 10-50 times higher than those of rainwater. Urban fogs reflect in their composition the effect of local emissions. Occasionally, very acidic fogs, often due to HCl contamination, with pH values as low as 2 were observed. Fogs can affect ecosystems by concentrating, moving, and depositing chemicals and atmospheric pollutants. Basically, the major composition of fogwater results from the interaction of SO/sub 2/, NO/sub x/, CO/sub 2/, HCl, and NH/sub 3/ with H/sub 2/O in an oxidative environment (O/sub 2/, O/sub 3/, OH/sup ./, H/sub 2/O/sub 2/, sunlight) and in the presence of some traces that may act as redox catalysts (metals such as Cu, Fe, Mn, organic material such as hydrocarbons, and dust and soot surfaces). - The composition of numerous (radiation type) ground-level fogs, and their variation with time from formation to dissipation, have been investigated in Duebendorf (near Zuerich) in order to evaluate the factors that influence the composition; specifically to explore the mechanisms of NO/sub 3//sup -/ and SO/sub 4//sup 2/ incorperation Surprisingly constant motor propertions of NH/sub 4//sup +/:SO/sub 4//sup 2-/:NO/sub 3//sup -/ were observed in the fog. The results do not permit to establish unambiguously to what extent the inclusion of SO/sub 4//sup 2-/ and NO/sub 3//sup -/ into the fogwater is due to the oxidation of absorbed and dissolved SO/sub 2/ and the scavenging of gaseous HNO/sub 3/ or by dissolution of ambient previously formed ammonium sulfate and ammonium nitrate aerosols.

A simple property of the contribution of double scattered radiation to the lidar returnes from homogeneous fogs

International Nuclear Information System (INIS)

Bruscaglioni, P.

1979-01-01

By using the formulas presented in a previous paper for the calculation of the ratio D/S between the contributions of doubly scattered and singly scattered radiation to lidar returns from homogeneous fogs, it is shown that the ratio D/S is proportional to the lidar range, indipendently from the particular model of fog, i.e. from the assumed phase scattering function

Evidence for fat, oil, and grease (FOG) deposit formation mechanisms in sewer lines.

Science.gov (United States)

He, Xia; Iasmin, Mahbuba; Dean, Lisa O; Lappi, Simon E; Ducoste, Joel J; de los Reyes, Francis L

2011-05-15

The presence of hardened and insoluble fats, oil, and grease (FOG) deposits in sewer lines is a major cause of line blockages leading to sanitary sewer overflows (SSOs). Despite the central role that FOG deposits play in SSOs, little is known about the mechanisms of FOG deposit formation in sanitary sewers. In this study, FOG deposits were formed under laboratory conditions from the reaction between free fatty acids and calcium chloride. The calcium and fatty acid profile analysis showed that the laboratory-produced FOG deposit displayed similar characteristics to FOG deposits collected from sanitary sewer lines. Results of FTIR analysis showed that the FOG deposits are metallic salts of fatty acid as revealed by comparisons with FOG deposits collected from sewer lines and pure calcium soaps. Based on the data, we propose that the formation of FOG deposits occurs from the aggregation of excess calcium compressing the double layer of free fatty acid micelles and a saponification reaction between aggregated calcium and free fatty acids.

Numerical Modeling of Persistent Winter Fog over the Indo-Gangetic Plains

Science.gov (United States)

Ghimire, S.; Adhikary, B.; Praveen, P. S.; Panday, A. K.

2017-12-01

Every winter the Indo-Gangetic Plains (IGP) in northern South Asia; bounded by the great Himalayas in the north, are periodically covered by dense and persistent fog that severely impacts day-to-day activities of several hundred million people. The fog can stretch over several hundred kilometers and last several days in many locations. Despite the fog's high impact, there are very limited in-situ observations available to characterize persistent fog episodes. Also, there has been very little success to date in accurately predicting the fog occurrence and extent over a larger area such as IGP. This study will present insights into the performance of the Weather Research and Forecasting (WRF) model simulating persistent winter fog prediction in the IGP region, compared to satellite observations and in-situ measurements. Since fog is not a prognostic variable in WRF, the study presents results based on multi-rule diagnostic algorithms published in peer reviewed journals. In addition, fog episodes were analyzed using the Air Force Weather Agency (AFWA) diagnostics package available for WRF. On a regional scale, MODIS data onboard the TERRA and AQUA satellites are used to evaluate model performance skills. At a local scale, the model is evaluated at two sites in the southern Nepal, Lumbini and Chitwan, located in the IGP. Lumbini and Chitwan observatories have Luftt and Biral weather sensors which allow monitoring presence of fog, visibility range and surface meteorology. In addition, for Chitwan, data from DMT Fog Monitor (FM 120) and Luftt CHM 15K Ceilometer were used to compare model performance for liquid-water content and planetary boundary layer during foggy and non-foggy days.

Fog deposition fluxes of water and ions to a mountainous site in Central Europe

Science.gov (United States)

Klemm, Otto; Wrzesinsky, Thomas

2007-09-01

Fog and precipitation composition and deposition were measured over a 1-yr period. Ion concentrations were higher in fog than in precipitation by factors of between 6 and 18. The causes of these differences were less dilution of fog water due to non-availability of condensable water vapour, and more efficient transfer of surface emissions to fog water as compared to rain water or snow. Fogwater and dissolved ions depositions were measured with eddy covariance in combination with a bulk fogwater collector. Annual fogwater deposition was 9.4% that of precipitation. The annual deposition of ions through fog was of the same order as that for precipitation. Ammonium, representing local emission sources, had 46% more annual deposition through fog than through precipitation. The fog droplet number and mass size distributions are reported. Fog droplets of 15 μm diameter contribute most to the deposition flux. The variability of processes and parameters contributing to deposition of ions through fog (ion concentrations in fog water, liquid water content in air, fog duration and turbulence) is high.

Processing of atmospheric polycyclic aromatic hydrocarbons by fog in an urban environment.

Science.gov (United States)

Ehrenhauser, Franz S; Khadapkar, Kalindi; Wang, Youliang; Hutchings, James W; Delhomme, Olivier; Kommalapati, Raghava R; Herckes, Pierre; Wornat, Mary J; Valsaraj, Kalliat T

2012-10-26

Polycyclic aromatic hydrocarbons (PAH) are ubiquitous pollutants in the atmosphere, predominantly known for their toxicity. Although there has been substantial work on the atmospheric degradation of PAH, little is known about how the presence of atmospheric droplets (e.g., a fog cloud) affects the fate of PAH. In order to assess the processing of PAH and their corresponding oxidation products during a fog event, two field-sampling campaigns in Fresno, CA and Davis, CA were conducted. The simultaneous evaluation of concentrations of the PAH and oxygenated polycyclic aromatic compounds (OPAC) in the gas phase, particulate matter and fog water droplets before, during and after fog allows for the characterization of transformative and transport processes in a fog cloud. By tracking the ratio of OPAC to PAH in the individual atmospheric phases, two major polycyclic aromatic compounds-processing pathways can be identified: (i) the dissolution of OPAC from particulate matter and (ii) the uptake and oxidation of PAH in the fog water droplets. Wet deposition steadily decreases the pollutant concentration in the fog cloud droplets during a fog event; however, uptake and concentration via evaporative water loss upon the dissipation of a fog cloud cause an increase in the atmospheric pollutant concentration.

Mechanisms of fat, oil and grease (FOG) deposit formation in sewer lines.

Science.gov (United States)

He, Xia; de los Reyes, Francis L; Leming, Michael L; Dean, Lisa O; Lappi, Simon E; Ducoste, Joel J

2013-09-01

FOG deposits in sewer systems have recently been shown to be metallic salts of fatty acids. However, the fate and transport of FOG deposit reactant constituents and the complex interactions during the FOG deposit formation process are still largely unknown. In this study, batch tests were performed to elucidate the mechanisms of FOG deposit formation that lead to sanitary sewer overflows (SSOs). We report the first formation of FOG deposits on a concrete surface under laboratory conditions that mimic the formation of deposits in sewer systems. Results showed that calcium, the dominant metal in FOG deposits, can be released from concrete surfaces under low pH conditions and contribute to the formation process. Small amounts of additional oil to grease interceptor effluent substantially facilitated the air/water or pipe surface/water interfacial reaction between free fatty acids and calcium to produce surface FOG deposits. Tests of different fatty acids revealed that more viscous FOG deposit solids were formed on concrete surfaces, and concrete corrosion was accelerated, in the presence of unsaturated FFAs versus saturated FFAs. Based on all the data, a comprehensive model was proposed for the mechanisms of FOG deposit formation in sewer systems. Copyright © 2013 Elsevier Ltd. All rights reserved.

On the theoretical aspects of improved fog detection and prediction in India

Science.gov (United States)

Dey, Sagnik

2018-04-01

The polluted Indo-Gangetic Basin (IGB) in northern India experiences fog (a condition when visibility degrades below 1 km) every winter (Dec-Jan) causing a massive loss of economy and even loss of life due to accidents. This can be minimized by improved fog detection (especially at night) and forecasting so that activities can be reorganized accordingly. Satellites detect fog at night by a positive brightness temperature difference (BTD). However, fixing the right BTD threshold holds the key to accuracy. Here I demonstrate the sensitivity of BTD in response to changes in fog and surface emissivity and their temperatures and justify a new BTD threshold. Further I quantify the dependence of critical fog droplet number concentration, NF (i.e. minimum fog concentration required to degrade visibility below 1 km) on liquid water content (LWC). NF decreases exponentially with an increase in LWC from 0.01 to 1 g/m3, beyond which it stabilizes. A 10 times low bias in simulated LWC below 1 g/m3 would require 107 times higher aerosol concentration to form the required number of fog droplets. These results provide the theoretical aspects that will help improving the existing fog detection algorithm and fog forecasting by numerical models in India.

Crash risk analysis during fog conditions using real-time traffic data.

Science.gov (United States)

Wu, Yina; Abdel-Aty, Mohamed; Lee, Jaeyoung

2018-05-01

This research investigates the changes of traffic characteristics and crash risks during fog conditions. Using real-time traffic flow and weather data at two regions in Florida, the traffic patterns at the fog duration were compared to the traffic patterns at the clear duration. It was found that the average 5-min speed and the average 5-min volume were prone to decreasing during fog. Based on previous studies, a "Crash Risk Increase Indicator (CRII)" was proposed to explore the differences of crash risk between fog and clear conditions. A binary logistic regression model was applied to link the increase of crash risks with traffic flow characteristics. The results suggested that the proposed indicator worked well in evaluating the increase of crash risk under fog condition. It was indicated that the crash risk was prone to increase at ramp vicinities in fog conditions. Also, the average 5-min volume during fog and the lane position are important factors for crash risk increase. The differences between the regions were also explored in this study. The results indicated that the locations with heavier traffic or locations at the lanes that were closest to the median in Region 2 were more likely to observe an increase in crash risks in fog conditions. It is expected that the proposed indicator can help identify the dangerous traffic status under fog conditions and then proper ITS technologies can be implemented to enhance traffic safety when the visibility declines. Copyright © 2017 Elsevier Ltd. All rights reserved.

Spherical projections and liftings in geometric tomography

DEFF Research Database (Denmark)

Goodey, Paul; Kiderlen, Markus; Weil, Wolfgang

2011-01-01

We consider a variety of integral transforms arising in Geometric Tomography. It will be shown that these can be put into a common framework using spherical projection and lifting operators. These operators will be applied to support functions and surface area measures of convex bodies and to rad......We consider a variety of integral transforms arising in Geometric Tomography. It will be shown that these can be put into a common framework using spherical projection and lifting operators. These operators will be applied to support functions and surface area measures of convex bodies...... and to radial functions of star bodies. We then investigate averages of lifted projections and show that they correspond to self-adjoint intertwining operators. We obtain formulas for the eigenvalues of these operators and use them to ascertain circumstances under which tomographic measurements determine...... the original bodies. This approach via mean lifted projections leads us to some unexpected relationships between seemingly disparate geometric constructions....

Observations and modeling of fog by cloud radar and optical sensors

NARCIS (Netherlands)

Li, Y.; Hoogeboom, P.; Russchenberg, H.

2014-01-01

Fog is a significant factor affecting the public traffic because visibility is reduced to a large extent. Therefore the determination of optical visibility in fog from radar instruments has received much interest. To observe fog with radar, high frequency bands (millimeter waves) have the best

Fog-Assisted Operational Cost Reduction for Cloud Data Centers

OpenAIRE

Yu, Liang; Jiang, Tao; Zou, Yulong

2017-01-01

In this paper, we intend to reduce the operational cost of cloud data centers with the help of fog devices, which can avoid the revenue loss due to wide-area network propagation delay and save network bandwidth cost by serving nearby cloud users. Since fog devices may not be owned by a cloud service provider, they should be compensated for serving the requests of cloud users. When taking economical compensation into consideration, the optimal number of requests processed locally by each fog d...

Quantification of Fog Water Collection in Three Locations of Tenerife (Canary Islands

Directory of Open Access Journals (Sweden)

Axel Ritter

2015-06-01

Full Text Available We present the results of fog water collection obtained with cylindrical fog gauges at three locations on the northern side of Tenerife island (Spain: La Esperanza (1093 m a.s.l., Taborno (1015 m a.s.l., and El Gaitero (1747 m a.s.l.. Concomitant meteorological variables were also measured. We show that fog precipitation was more frequent than rainfall. However, the volumes and frequency of daily fog water collection varied among the three studied sites, usually not exceeding 10–40 L d−1/m2 of collecting surface. In La Esperanza, fog water harvesting occurred frequently, but was considerably lower than in the other two locations. However, while in Taborno fog water collection episodes were distributed throughout the period, in El Gaitero these were mainly concentrated in two periods, during autumn and winter 2012–2013. The study of the relationships between daily fog water yields and the averages of meteorological variables did not show any clear trend, but it suggested that the greater volumes of collected fog water were logically associated with higher wind speeds and lower solar radiation conditions. Fog water collection in La Esperanza and in Taborno typically occurred within a similar temperature interval (7.5–12.5 °C, while in El Gaitero the phenomenon was associated with a lower temperature range (2.5–10 °C.

Fog Water Collection: Challenges beyond Technology

OpenAIRE

Manzoor Qadir; Gabriela C. Jiménez; Rebecca L. Farnum; Leslie L. Dodson; Vladimir Smakhtin

2018-01-01

The Sustainable Development Goal (SDG) 6, calling for access to safe water and sanitation for all by the year 2030 supports the efforts in water-scarce countries and regions to go beyond conventional resources and tap unconventional water supplies to narrow the water demand-supply gap. Among the unconventional water resources, the potential to collect water from the air, such as fog harvesting, is by far the most under-explored. Fog water collection is a passive, low maintenance, and sustaina...

Cool PDO phase leads to recent rebound in coastal southern California fog

Directory of Open Access Journals (Sweden)

Witiw, Michael R.

2015-12-01

Full Text Available The relationship between coastal fog in southern California and the Pacific Decadal Oscillation (PDO is investigated during the last decade. Fog occurrence was examined at two locations in southern California: San Diego and Los Angeles international airports. Both locations are located near the Pacific coast with strong marine influences. The period looked at was 2001 through 2012. The cool season (October-March and warm season (April-September were examined separately because of the different types of fog that prevail in each season. Previous studies have shown a relation between fog and the Pacific Decadal Oscillation (PDO. However, a switch in polarity in the PDO in the mid-1970s (from a cool to a warm phase coupled with a sharp decrease in particulate concentrations calls into question the strong relationship shown. Further studies suggest that the decrease in dense fog seen from the 1960s through the 1990s was largely due to increasing urban heat island effects coupled with a decrease in atmospheric particulate matter. Since 1998, the PDO again changed polarity and fog frequencies began to rise. However, urban heat island and particulate effects were relatively constant making it easier to isolate any effects of the PDO on fog occurrence. Previous studies examined the occurrence of dense fog (visibility less than 400 meters, but because of the decrease in fog in this category, 800 meters was chosen this time. That also corresponds to the 0.5 mile visibility which triggers special reports at the California airports when visibility moves through this threshold. Although there was no strong relationship between fog and PDO in the most recent period, Pacific Ocean oscillations were found to show significant relationships with fog frequencies historically. Upwelling indices show a significant relationship with fog frequencies when examined by the phase of the PDO. Even stronger relationships are found when selecting La Niña and El Niño events.

Urban Heat Island Over Delhi Punches Holes in Widespread Fog in the Indo-Gangetic Plains

Science.gov (United States)

Gautam, Ritesh; Singh, Manoj K.

2018-01-01

Persistent and widespread fog affects several densely populated and agriculturally fertile basins around the world. Dense and polluted fog is especially known to impact transportation, air quality, and public health. Here we report a striking observation of holes in fog over urban areas in satellite imagery. The extent of fog holes appear highly correlated with city populations in fog-prevalent regions of Asia, Europe, and the United States. We find the highest frequency and largest extent of fog holes over Delhi along with suppressed fog fraction, amidst increased fog occurrence over the Indo-Gangetic Plains, based on 17 years of satellite data (2000-2016). This apparent urban heat impact is characterized in sharp urban-rural gradients in surface temperatures and fog thickness. Urban heating seems to have already amplified the long-term fog decline in Europe and the United States and should be assessed over regions undergoing urban expansion including India, where no previous linkages are reported between urban heating and fog.

Mortality, fog and atmospheric pollution

Energy Technology Data Exchange (ETDEWEB)

Martin, A E; Bradley, W H

1960-01-01

A study was made associating climate and atmospheric pollution with excess mortality in greater London during the winter of 1958 and 1959. It was a particularly foggy winter with 6 major episodes, 4 of which resembled previous dangerous smogs. There were two additional periods of high pollution without fog. Excess mortality during these 8 periods ranged from 70 to 230. During one period, a flu epidemic accompanied the fog. In 4 to 6 foggy periods, morbidity (hospital bed demand) also increased. This small number of observations indicates mortality association: on 2/3 of days with high SO/sub 2/ (2.5 pphM) or high particulate soot (10 mg/m/sup 3/), and on all days with thick fog, there was an increase in mortality (20 deaths more than previous day) on that or the following day. Fifteen-day moving mortality index and bronchitis mortality index were significantly correlated with black suspended matter and SO/sub 2/; association with pneumonia was not significant. Also little or no relation between mortality and humidity, mean temperature, or barometric pressure was found. Rapid response of mortality to air pollution may indicate that pollution affects mostly those already ill.

Fog-water harvesting along the West Coast of South Africa: a ...

African Journals Online (AJOL)

Many parts of the West Coast of South Africa experience severe water shortages throughout the year. Despite the meager rainfall, however, the region is subject to a high incidence of fog which might provide water for water-poor communities. This paper investigates the fog water potential of the area. Since fog water ...

Multirule Based Diagnostic Approach for the Fog Predictions Using WRF Modelling Tool

Directory of Open Access Journals (Sweden)

Swagata Payra

2014-01-01

Full Text Available The prediction of fog onset remains difficult despite the progress in numerical weather prediction. It is a complex process and requires adequate representation of the local perturbations in weather prediction models. It mainly depends upon microphysical and mesoscale processes that act within the boundary layer. This study utilizes a multirule based diagnostic (MRD approach using postprocessing of the model simulations for fog predictions. The empiricism involved in this approach is mainly to bridge the gap between mesoscale and microscale variables, which are related to mechanism of the fog formation. Fog occurrence is a common phenomenon during winter season over Delhi, India, with the passage of the western disturbances across northwestern part of the country accompanied with significant amount of moisture. This study implements the above cited approach for the prediction of occurrences of fog and its onset time over Delhi. For this purpose, a high resolution weather research and forecasting (WRF model is used for fog simulations. The study involves depiction of model validation and postprocessing of the model simulations for MRD approach and its subsequent application to fog predictions. Through this approach model identified foggy and nonfoggy days successfully 94% of the time. Further, the onset of fog events is well captured within an accuracy of 30–90 minutes. This study demonstrates that the multirule based postprocessing approach is a useful and highly promising tool in improving the fog predictions.

Dynamics of normal and superfluid fogs using diffusing-wave spectroscopy

International Nuclear Information System (INIS)

Kim, Heetae; Lemieux, Pierre-Anthony; Durian, Douglas J.; Williams, Gary A.

2004-01-01

The dynamics of normal and superfluid fogs are studied using the technique of diffusing-wave spectroscopy. For a water fog generated with a 1.75 MHz piezoelectric driver below the liquid surface, the 7 μm diameter droplets are found to have diffusive dynamics for correlation times long compared to the viscous time. For a fog of 10 μm diameter superfluid helium droplets in helium vapor at 1.5 K the motion appears to be ballistic for correlation times short compared to the viscous time. The velocity correlations between the helium droplets are found to depend on the initial velocity with which the droplets are injected from the helium surface into the fog

Continental Fog Attenuation Empirical Relationship from Measured Visibility Data

Directory of Open Access Journals (Sweden)

F. Nadeem

2010-12-01

Full Text Available Free Space Optics (FSO has the great potential for future communication applications. However, weather influenced reduced availability had been the main cause for its restricted growth. Among different weather influences fog plays the major role. A new model generalized for all FSO wavelengths, has been proposed for the prediction of continental fog attenuation using visibility data. The performance of the proposed model has been compared with well known models for measured attenuation data of Continental fog. The comparison has been performed in terms of Root Mean Square Error (RMSE.

[Optical properties of aerosol during haze-fog episodes in Beijing].

Science.gov (United States)

Yu, Xing-Na; Li, Xin-Mei; Deng, Zen-Grandeng; De, Qing-Yangzong; Yuan, Shuai

2012-04-01

The purpose of this study is to investigate the optical properties of aerosol during haze-fog episodes in Beijing. The aerosol optical depth (AOD), Angstrom exponent (alpha), size distribution and single scattering albedo (omega) during haze-fog episodes were analyzed between 2002 and 2008 using AERONENT data. During haze-fog episodes, the aerosol optical depth showed a decreasing trend with wavelengths, and showed high values with an average 1.34 at 440 nm. The magnitude of Angstrom exponent was relatively high during haze-fog episodes and the mean values reached 1.11. The frequency distribution of alpha was up to 94% when alpha > 0.9, indicating the predominance of fine particles during haze-fog episodes in Beijing. The aerosol volume size distributions presented a bimodal structure (fine and coarse modes). The maxima (peaks) radius of fine mode showed an increasing trend with AOD, however, those of coarse mode showed a decreasing trend with AOD. The size distribution showed a distinct difference in dominant mode for the different AOD. The single scattering albedo showed an increasing trend with AOD during haze-fog episodes in Beijing. The mean value of omega was 0.89 at the four wavelengths and the omega exhibited a low sensitivity to wavelengths.

Real-time WAMI streaming target tracking in fog

Science.gov (United States)

Chen, Yu; Blasch, Erik; Chen, Ning; Deng, Anna; Ling, Haibin; Chen, Genshe

2016-05-01

Real-time information fusion based on WAMI (Wide-Area Motion Imagery), FMV (Full Motion Video), and Text data is highly desired for many mission critical emergency or security applications. Cloud Computing has been considered promising to achieve big data integration from multi-modal sources. In many mission critical tasks, however, powerful Cloud technology cannot satisfy the tight latency tolerance as the servers are allocated far from the sensing platform, actually there is no guaranteed connection in the emergency situations. Therefore, data processing, information fusion, and decision making are required to be executed on-site (i.e., near the data collection). Fog Computing, a recently proposed extension and complement for Cloud Computing, enables computing on-site without outsourcing jobs to a remote Cloud. In this work, we have investigated the feasibility of processing streaming WAMI in the Fog for real-time, online, uninterrupted target tracking. Using a single target tracking algorithm, we studied the performance of a Fog Computing prototype. The experimental results are very encouraging that validated the effectiveness of our Fog approach to achieve real-time frame rates.

Effect of water fogs on the deliberate ignition of hydrogen. Final report

International Nuclear Information System (INIS)

Zalosh, R.G.; Bajpai, S.N.

1982-11-01

This report presents an experimental evaluation of the effects of water fog density, droplet diameter, and temperature on the lower flammable limit (LFL) of hydrogen-air-steam mixtures. The results show that the LFL for hydrogen in air at 20 0 C is only marginally higher with fog than without. Most of the nozzles tested at 20 0 C raised the hydrogen LFL from 4.0 vol % to about 4.8%, for the case of dense fogs with volume-average drop size in the range 45 to 90 microns. The lower flammable limit at 50 0 C was typically 7.2% for dense fogs with drop size in the range 25 to 50 microns. The lower flammable limit at 70 0 C was typically 7.6%. Typical fog concentrations ranged from 0.03 to 0.09 vol % at 20 0 C and decreased with increasing fog temperature. 7 figures, 4 tables

Salt Fog Testing Iron-Based Amorphous Alloys

International Nuclear Information System (INIS)

Rebak, Raul B.; Aprigliano, Louis F.; Day, S. Daniel; Farmer, Joseph C.

2007-01-01

Iron-based amorphous alloys are hard and highly corrosion resistant, which make them desirable for salt water and other applications. These alloys can be produced as powder and can be deposited as coatings on any surface that needs to be protected from the environment. It was of interest to examine the behavior of these amorphous alloys in the standard salt-fog testing ASTM B 117. Three different amorphous coating compositions were deposited on 316L SS coupons and exposed for many cycles of the salt fog test. Other common engineering alloys such as 1018 carbon steel, 316L SS and Hastelloy C-22 were also tested together with the amorphous coatings. Results show that amorphous coatings are resistant to rusting in salt fog. Partial devitrification may be responsible for isolated rust spots in one of the coatings. (authors)

Giant-FOG: A new player in ground motion instrumentation

Science.gov (United States)

Guattari, F.; de Toldi, E.; Bigueur, A.; Decitre, J. B.; Ponceau, D.; Sèbe, O.; Frenois, A.; Schindelé, F.; Moluçon, C.; Gaffet, S.; Ducloux, E.; Lefèvre, H.

2017-12-01

Based on recent experiences developing very low noise fiber-optic gyroscopes (FOG), first performance results on very large fiber-optic coils of up to 1m diameter are presented. The goal for constructing large FOGs is to evaluate experimentally the physical limits of this kind of technology and to reach the lowest possible noise. While these experiments are probing the fundamental limits of the FOG technology, they also serves as a first step for a cost effective very low noise laboratory rotational seismometer, which could be a game changer in instrumentation of ground motion. Build a Giant-FOG has several difficulties: The first is winding of the coil, the second concerns the mechanical substrate, and third is related to the measurement. - To our knowledge, a winding machine, large enough to wind coil of a 1 meter diameter, does not exist, but thanks to the iXblue expertise in the manufacturing of winding machines and calibration tables, a hydride system has been designed, merging these two technology to fulfill the requirement of winding a large coil on an adequate rotational platform. The characterization of the wobbles of the system will be presented, since this is a critical parameter for the winding and ultimately the performance. - To achieve the highest attainable measurement sensitivity to the real ground rotation, the design of the mechanical substrate of the coil is critical to reduce as much as possible the sensor sensitivities to environmental noises. A preliminary assessment of the global noise performance of the 1m diameter FOG sensor will be presented. - To demonstrate the on-site performance, the low noise inter-disciplinary underground laboratory (LSBB, Rustrel, France), with a dense array of precisely oriented broad-band seismometers, provides the possibility to compare Large FOG rotation records with Array Derivated Rotation measurement method. Results of different prototypes during the development process will be presented to underline the

Regional changes in spine posture at lift onset with changes in lift distance and lift style

NARCIS (Netherlands)

Gill, K.P.; Bennet, S.J.; Savelsbergh, G.J.P.; van Dieen, J.H.

2007-01-01

STUDY DESIGN. Repeated measures experiment. OBJECTIVE. To determine the effect of changes in horizontal lift distance on the amount of flexion, at lift onset, in different spine regions when using different lift styles. SUMMARY OF BACKGROUND DATA. By approximating spine bending during lifting as a

Machine learning based Intelligent cognitive network using fog computing

Science.gov (United States)

Lu, Jingyang; Li, Lun; Chen, Genshe; Shen, Dan; Pham, Khanh; Blasch, Erik

2017-05-01

In this paper, a Cognitive Radio Network (CRN) based on artificial intelligence is proposed to distribute the limited radio spectrum resources more efficiently. The CRN framework can analyze the time-sensitive signal data close to the signal source using fog computing with different types of machine learning techniques. Depending on the computational capabilities of the fog nodes, different features and machine learning techniques are chosen to optimize spectrum allocation. Also, the computing nodes send the periodic signal summary which is much smaller than the original signal to the cloud so that the overall system spectrum source allocation strategies are dynamically updated. Applying fog computing, the system is more adaptive to the local environment and robust to spectrum changes. As most of the signal data is processed at the fog level, it further strengthens the system security by reducing the communication burden of the communications network.

Characterization of mineral particles in winter fog of Beijing analyzed by TEM and SEM.

Science.gov (United States)

Li, Weijun; Shao, Longyi

2010-02-01

Aerosol samples were collected during winter fog and nonfog episodes in Beijing. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were applied to study morphologies, sizes, and compositions of aerosol particles. TEM observation indicates that most mineral particles collected in fog episode are scavenged in fog droplets. Number-size distributions of mineral particles collected in fog and nonfog episodes show two main peaks at the ranges of 0.1-0.3 and 1-2.5 microm, respectively. Based on their major compositions, mineral particles mainly include Si-rich, Ca-rich, and S-rich. Average S/Ca ratio of mineral particles collected in fog episode is 6.11, being eight times higher than that in nonfog episodes. Development mechanism of individual mineral particles in fog droplets is proposed. It is suggested that mineral particles with abundant alkaline components (e.g., "Ca-rich" particles) occurred in air should alleviate acidic degree of fog and contribute to complexity of fog droplets in Beijing.

Fogs: Physical Basis, Characteristic Properties, and Impacts on the Environment and Human Health

Directory of Open Access Journals (Sweden)

José L. Pérez-Díaz

2017-10-01

Full Text Available This work presents a selective overview of natural fogs in terms of fog types, forms and states of occurrence, physical, micro-physical, chemical and dynamic properties, basic characterizing parameters, etc. In focus are related achievements and contributions reported mainly during the last decade and a half, as a result of both laboratory studies and field observations. Processes of homogeneous and heterogeneous nucleation are analyzed in the aspects of condensation, nuclei diversity and specifics, as related to the activation, growth and deposition of fog droplets. The effect is highlighted of the water vapor’s partial pressure on the surface tension of the liquid water–air interface and the freezing point of the water droplets. Some problems and aspects of fog modeling, parameterization, and forecasting are outlined and discussed on the examples of newly developed relevant 1D/3D theoretical models. Important issues of fog impacts on the air quality, ecosystems, water basins, societal life, and human health are also addressed and discussed, particularly in cases of anthropogenically modified (chemical, radioactive, etc. fogs. In view of reducing the possible negative effects of fogs, conclusions are drawn concerning the new demands and challenges to fog characterization imposed by the changing natural and social environment and the needs for new data on and approaches to more adequate observations of fog-related events.

What is brain fog? An evaluation of the symptom in postural tachycardia syndrome.

Science.gov (United States)

Ross, Amanda J; Medow, Marvin S; Rowe, Peter C; Stewart, Julian M

2013-12-01

Adolescents with postural tachycardia syndrome (POTS) often experience ill-defined cognitive impairment referred to by patients as "brain fog." The objective of this study was to evaluate the symptom of brain fog as a means of gaining further insight into its etiology and potential palliative interventions. Eligible subjects who reported having been diagnosed with POTS were recruited from social media web sites. Subjects were asked to complete a 38-item questionnaire designed for this study, and the Wood mental fatigue inventory (WMFI). Responses were received from 138 subjects with POTS (88 % female), ranging in age from 14 to 29 years; 132 subjects reported brain fog. WMFI scores correlated with brain fog frequency and severity (P fog were "forgetful," "cloudy," and "difficulty focusing, thinking and communicating." The most frequently reported brain fog triggers were fatigue (91 %), lack of sleep (90 %), prolonged standing (87 %), dehydration (86 %), and feeling faint (85 %). Although aggravated by upright posture, brain fog was reported to persist after assuming a recumbent posture. The most frequently reported interventions for the treatment of brain fog were intravenous saline (77 %), stimulant medications (67 %), salt tablets (54 %), intra-muscular vitamin B-12 injections (48 %), and midodrine (45 %). Descriptors for "brain fog" are most consistent with it being a cognitive complaint. Factors other than upright posture may play a role in the persistence of this symptom. Subjects reported a number of therapeutic interventions for brain fog not typically used in the treatment of POTS that may warrant further investigation.

Coastal Fog in Atlantic Canada: Characterization and Projection in a Changing Climate

Science.gov (United States)

Duplessis, P.; Hartery, S.; Macdonald, A. M.; Wheeler, M.; Miller, J.; Bhatia, S.; Chang, R. Y. W.

2016-12-01

Marine and coastal fog in Atlantic Canada is usually advective and favored by the meeting of the warm Gulf Stream and cold Labrador Current. As moist warm air moves over cold water, it cools down and becomes supersaturated. The interactions between microphysical, dynamical and radiative processes can also be a determining element in the formation and persistence of fog, which makes fog forecasting a highly challenging task. Current parameterizations within models suffer notably from unresolved microphysical problems such as neglecting droplet concentration, which leads to errors in droplet density predictions of up to 50%. In the scope of improving our understanding of fog and its characteristics, our research group conducted a field study on the coast of Nova Scotia in Eastern Canada during the fog season of 2016. Meteorological variables, droplet and aerosol size distributions, chemical speciation and fog water composition were measured. Results from this study will be presented, along with projections in a changing climate.

76 FR 44906 - Foremost 4809-ES Insect-O-Fog; Amended Cancellation Order

Science.gov (United States)

2011-07-27

... ENVIRONMENTAL PROTECTION AGENCY [EPA-HQ-OPP-2009-1017; FRL-8880-8] Foremost 4809-ES Insect-O-Fog... cancellation order for the pesticide product Foremost 4809-ES Insect-O-Fog, a pesticide product containing Piperonyl Butoxide and Pyrethrins. The registrant of Foremost 4809-ES Insect-O-Fog--Delta Foremost Chemical...

Quantification of Fog Water Collection in Three Locations of Tenerife (Canary Islands)

OpenAIRE

Ritter, Axel; Regalado, Carlos; Guerra, Juan

2015-01-01

We present the results of fog water collection obtained with cylindrical fog gauges at three locations on the northern side of Tenerife island (Spain): La Esperanza (1093 m a.s.l.), Taborno (1015 m a.s.l.), and El Gaitero (1747 m a.s.l.). Concomitant meteorological variables were also measured. We show that fog precipitation was more frequent than rainfall. However, the volumes and frequency of daily fog water collection varied among the three studied sites, usually not exceeding 10–40 L d−1/...

SUMOylation regulates the transcriptional repression activity of FOG-2 and its association with GATA-4.

Science.gov (United States)

Perdomo, José; Jiang, Xing-Mai; Carter, Daniel R; Khachigian, Levon M; Chong, Beng H

2012-01-01

Friend of GATA 2 (FOG-2), a co-factor of several GATA transcription factors (GATA-4, -5 and 6), is a critical regulator of coronary vessel formation and heart morphogenesis. Here we demonstrate that FOG-2 is SUMOylated and that this modification modulates its transcriptional activity. FOG-2 SUMOylation occurs at four lysine residues (K324, 471, 915, 955) [corrected]. Three of these residues are part of the characteristic SUMO consensus site (ψKXE), while K955 is found in the less frequent TKXE motif. Absence of SUMOylation did not affect FOG-2's nuclear localization. However, mutation of the FOG-2 SUMOylation sites, or de-SUMOylation, with SENP-1 or SENP-8 resulted in stronger transcriptional repression activity in both heterologous cells and cardiomyocytes. Conversely, increased FOG-2 SUMOylation by overexpression of SUMO-1 or expression of a SUMO-1-FOG-2 fusion protein rendered FOG-2 incapable of repressing GATA-4-mediated activation of the B-type natriuretic peptide (BNP) promoter. Moreover, we demonstrate both increased interaction between a FOG-2 SUMO mutant and GATA-4 and enhanced SUMOylation of wild-type FOG-2 by co-expression of GATA-4. These data suggest a new dynamics in which GATA-4 may alter the activity of FOG-2 by influencing its SUMOylation status.

High repetition rate ultrashort laser cuts a path through fog

Science.gov (United States)

de la Cruz, Lorena; Schubert, Elise; Mongin, Denis; Klingebiel, Sandro; Schultze, Marcel; Metzger, Thomas; Michel, Knut; Kasparian, Jérôme; Wolf, Jean-Pierre

2016-12-01

We experimentally demonstrate that the transmission of a 1030 nm, 1.3 ps laser beam of 100 mJ energy through fog increases when its repetition rate increases to the kHz range. Due to the efficient energy deposition by the laser filaments in the air, a shockwave ejects the fog droplets from a substantial volume of the beam, at a moderate energy cost. This process opens prospects for applications requiring the transmission of laser beams through fogs and clouds.

Enhanced toxicity of aerosol in fog conditions in the Po Valley, Italy

Science.gov (United States)

Decesari, Stefano; Sowlat, Mohammad Hossein; Hasheminassab, Sina; Sandrini, Silvia; Gilardoni, Stefania; Facchini, Maria Cristina; Fuzzi, Sandro; Sioutas, Constantinos

2017-06-01

While numerous studies have demonstrated the association between outdoor exposure to atmospheric particulate matter (PM) and adverse health effects, the actual chemical species responsible for PM toxicological properties remain a subject of investigation. We provide here reactive oxygen species (ROS) activity data for PM samples collected at a rural site in the Po Valley, Italy, during the fog season (i.e., November-March). We show that the intrinsic ROS activity of Po Valley PM, which is mainly composed of biomass burning and secondary aerosols, is comparable to that of traffic-related particles in urban areas. The airborne concentration of PM components responsible for the ROS activity decreases in fog conditions, when water-soluble species are scavenged within the droplets. Due to this partitioning effect of fog, the measured ROS activity of fog water was contributed mainly by water-soluble organic carbon (WSOC) and secondary inorganic ions rather than by transition metals. We found that the intrinsic ROS activity of fog droplets is even greater (> 2.5 times) than that of the PM on which droplets are formed, indicating that redox-active compounds are not only scavenged from the particulate phase, but are also produced within the droplets. Therefore, even if fog formation exerts a scavenging effect on PM mass and redox-active compounds, the aqueous-phase formation of reactive secondary organic compounds can eventually enhance ROS activity of PM when fog evaporates. These findings, based on a case study during a field campaign in November 2015, indicate that a significant portion of airborne toxicity in the Po Valley is largely produced by environmental conditions (fog formation and fog processing) and not simply by the emission and transport of pollutants.

Tornado lift

OpenAIRE

Ivanchin, Alexander

2010-01-01

It is shown that one of the causes for tornado is Tornado Lift. At increasing vortex diameter its kinetic energy decreases to keep the moment of momentum constant. A kinetic energy gradient of such vortex is Tornado Lift. Evaluation shows that contribution of Tornado Lift in air lifting in a tornado is comparable to buoyancy according to the order of magnitude.

Optimization of lift gas allocation in a gas lifted oil field as non-linear optimization problem

Directory of Open Access Journals (Sweden)

Roshan Sharma

2012-01-01

Full Text Available Proper allocation and distribution of lift gas is necessary for maximizing total oil production from a field with gas lifted oil wells. When the supply of the lift gas is limited, the total available gas should be optimally distributed among the oil wells of the field such that the total production of oil from the field is maximized. This paper describes a non-linear optimization problem with constraints associated with the optimal distribution of the lift gas. A non-linear objective function is developed using a simple dynamic model of the oil field where the decision variables represent the lift gas flow rate set points of each oil well of the field. The lift gas optimization problem is solved using the emph'fmincon' solver found in MATLAB. As an alternative and for verification, hill climbing method is utilized for solving the optimization problem. Using both of these methods, it has been shown that after optimization, the total oil production is increased by about 4. For multiple oil wells sharing lift gas from a common source, a cascade control strategy along with a nonlinear steady state optimizer behaves as a self-optimizing control structure when the total supply of lift gas is assumed to be the only input disturbance present in the process. Simulation results show that repeated optimization performed after the first time optimization under the presence of the input disturbance has no effect in the total oil production.

Prediction of peak back compressive forces as a function of lifting speed and compressive forces at lift origin and destination - a pilot study.

Science.gov (United States)

Greenland, Kasey O; Merryweather, Andrew S; Bloswick, Donald S

2011-09-01

To determine the feasibility of predicting static and dynamic peak back-compressive forces based on (1) static back compressive force values at the lift origin and destination and (2) lifting speed. Ten male subjects performed symmetric mid-sagittal floor-to-shoulder, floor-to-waist, and waist-to-shoulder lifts at three different speeds (slow, medium, and fast), and with two different loads (light and heavy). Two-dimensional kinematics and kinetics were captured. Linear regression analyses were used to develop prediction equations, the amount of predictability, and significance for static and dynamic peak back-compressive forces based on a static origin and destination average (SODA) back-compressive force. Static and dynamic peak back-compressive forces were highly predicted by the SODA, with R(2) values ranging from 0.830 to 0.947. Slopes were significantly different between slow and fast lifting speeds (p assessments at the origin and destination of a lifting task. This could be valuable for enhancing job design and analysis in the workplace and for large-scale studies where a full analysis of each lifting task is not feasible.

Urbanization Causes Increased Cloud Base Height and Decreased Fog in Coastal Southern California

Science.gov (United States)

Williams, A. Park; Schwartz, Rachel E.; Iacobellis, Sam; Seager, Richard; Cook, Benjamin I.; Still, Christopher J.; Husak, Gregory; Michaelsen, Joel

2015-01-01

Subtropical marine stratus clouds regulate coastal and global climate, but future trends in these clouds are uncertain. In coastal Southern California (CSCA), interannual variations in summer stratus cloud occurrence are spatially coherent across 24 airfields and dictated by positive relationships with stability above the marine boundary layer (MBL) and MBL height. Trends, however, have been spatially variable since records began in the mid-1900s due to differences in nighttime warming. Among CSCA airfields, differences in nighttime warming, but not daytime warming, are strongly and positively related to fraction of nearby urban cover, consistent with an urban heat island effect. Nighttime warming raises the near-surface dew point depression, which lifts the altitude of condensation and cloud base height, thereby reducing fog frequency. Continued urban warming, rising cloud base heights, and associated effects on energy and water balance would profoundly impact ecological and human systems in highly populated and ecologically diverse CSCA.

An automated fog monitoring system for the Indo-Gangetic Plains based on satellite measurements

Science.gov (United States)

Patil, Dinesh; Chourey, Reema; Rizvi, Sarwar; Singh, Manoj; Gautam, Ritesh

2016-05-01

Fog is a meteorological phenomenon that causes reduction in regional visibility and affects air quality, thus leading to various societal and economic implications, especially disrupting air and rail transportation. The persistent and widespread winter fog impacts the entire the Indo-Gangetic Plains (IGP), as frequently observed in satellite imagery. The IGP is a densely populated region in south Asia, inhabiting about 1/6th of the world's population, with a strong upward pollution trend. In this study, we have used multi-spectral radiances and aerosol/cloud retrievals from Terra/Aqua MODIS data for developing an automated web-based fog monitoring system over the IGP. Using our previous and existing methodologies, and ongoing algorithm development for the detection of fog and retrieval of associated microphysical properties (e.g. fog droplet effective radius), we characterize the widespread fog detection during both daytime and nighttime. Specifically, for the night time fog detection, the algorithm employs a satellite-based bi-spectral brightness temperature difference technique between two spectral channels: MODIS band-22 (3.9μm) and band-31 (10.75μm). Further, we are extending our algorithm development to geostationary satellites, for providing continuous monitoring of the spatial-temporal variation of fog. We anticipate that the ongoing and future development of a fog monitoring system would be of assistance to air, rail and vehicular transportation management, as well as for dissemination of fog information to government agencies and general public. The outputs of fog detection algorithm and related aerosol/cloud parameters are operationally disseminated via http://fogsouthasia.com/.

A review of observations of organic matter in fogs and clouds: Origin, processing and fate

Science.gov (United States)

Herckes, Pierre; Valsaraj, Kalliat T.; Collett, Jeffrey L.

2013-10-01

While fog and cloud composition has been studied for decades, most of the research was limited to inorganic species and fog acidity. Recently the focus has shifted towards organic matter in the atmospheric aqueous phase of fogs and clouds: its origin, reactivity and fate. An impressive number of fog and cloud chemistry observational studies have been performed over the last decade throughout the world. In the present work we will review the state of knowledge of atmospheric organic matter processing by fogs, with a focus on field observations. We start by reviewing observational studies in general and then discuss our knowledge on the occurrence of organic matter in fogs, its solubility, characterization and molecular speciation. Organic carbon concentrations can vary widely from approximately 1 mg C/L in remote marine environments to more than 100 mg C/L in polluted radiation fogs, accounting for a substantial part of fogwater solutes. The carbonaceous material can enter the droplets from the gas and particle phase and the scavenging behavior of fogs will be detailed. Observational studies showed evidence of aqueous phase transformation of organic material, in particular secondary organic aerosol (SOA) generation, in fog. Recent observations of biological material in fog suggest also an impact of biological processing within the droplets on fog organic matter. The review will end with a discussion of the impact of fog on the deposition fluxes of organic material and hence its atmospheric lifetime.

The Design of Wheelchair Lifting Mechanism and Control System

Institute of Scientific and Technical Information of China (English)

ZHAO Cong; WANG Zheng-xing; JIANG Shi-hong; ZHANG Li; LIU Zheng-yu

2014-01-01

In order to achieve a wheelchair lift function, this paper designs a tri-scissors mechanism. Through the so-called H-type transmission and L-type swing rod, the three scissors mechanisms lift in the same rate with only one liner motor while ensuring the stability of the lift. Finite element analysis in ANSYS is performed to verify the material strength. The control system with Sunplus SCM achieves the voice control of wheelchair walking and lifting.

Radio Astronomers Lift "Fog" on Milky Way's Dark Heart: Black Hole Fits Inside Earth's Orbit

Science.gov (United States)

2004-04-01

Thirty years after astronomers discovered the mysterious object at the exact center of our Milky Way Galaxy, an international team of scientists has finally succeeded in directly measuring the size of that object, which surrounds a black hole nearly four million times more massive than the Sun. This is the closest telescopic approach to a black hole so far and puts a major frontier of astrophysics within reach of future observations. The scientists used the National Science Foundation's Very Long Baseline Array (VLBA) radio telescope to make the breakthrough. Milky Way Nucleus The Milky Way's nucleus, as seen with the VLA. Sagittarius A* is the bright white dot at center. CREDIT: NRAO/AUI/NSF, Jun-Hui Zhao, W.M. Goss (Click on Image for Larger Version) "This is a big step forward," said Geoffrey Bower, of the University of California-Berkeley. "This is something that people have wanted to do for 30 years," since the Galactic center object, called Sagittarius A* (pronounced "A-star"), was discovered in 1974. The astronomers reported their research in the April 1 edition of Science Express. "Now we have a size for the object, but the mystery about its exact nature still remains," Bower added. The next step, he explained, is to learn its shape, "so we can tell if it is jets, a thin disk, or a spherical cloud." The Milky Way's center, 26,000 light-years from Earth, is obscured by dust, so visible-light telescopes cannot study the object. While radio waves from the Galaxy's central region can penetrate the dust, they are scattered by turbulent charged plasma in the space along the line of sight to Earth. This scattering had frustrated earlier attempts to measure the size of the central object, just as fog blurs the glare of distant lighthouses. "After 30 years, radio telescopes finally have lifted the fog and we can see what is going on," said Heino Falcke, of the Westerbork Radio Observatory in the Netherlands, another member of the research team. The bright, radio

Fog Density Estimation and Image Defogging Based on Surrogate Modeling for Optical Depth.

Science.gov (United States)

Jiang, Yutong; Sun, Changming; Zhao, Yu; Yang, Li

2017-05-03

In order to estimate fog density correctly and to remove fog from foggy images appropriately, a surrogate model for optical depth is presented in this paper. We comprehensively investigate various fog-relevant features and propose a novel feature based on the hue, saturation, and value color space which correlate well with the perception of fog density. We use a surrogate-based method to learn a refined polynomial regression model for optical depth with informative fog-relevant features such as dark-channel, saturation-value, and chroma which are selected on the basis of sensitivity analysis. Based on the obtained accurate surrogate model for optical depth, an effective method for fog density estimation and image defogging is proposed. The effectiveness of our proposed method is verified quantitatively and qualitatively by the experimental results on both synthetic and real-world foggy images.

Lower complexity bounds for lifted inference

DEFF Research Database (Denmark)

Jaeger, Manfred

2015-01-01

instances of the model. Numerous approaches for such “lifted inference” techniques have been proposed. While it has been demonstrated that these techniques will lead to significantly more efficient inference on some specific models, there are only very recent and still quite restricted results that show...... the feasibility of lifted inference on certain syntactically defined classes of models. Lower complexity bounds that imply some limitations for the feasibility of lifted inference on more expressive model classes were established earlier in Jaeger (2000; Jaeger, M. 2000. On the complexity of inference about...... that under the assumption that NETIME≠ETIME, there is no polynomial lifted inference algorithm for knowledge bases of weighted, quantifier-, and function-free formulas. Further strengthening earlier results, this is also shown to hold for approximate inference and for knowledge bases not containing...

SUMOylation regulates the transcriptional repression activity of FOG-2 and its association with GATA-4.

Directory of Open Access Journals (Sweden)

José Perdomo

Full Text Available Friend of GATA 2 (FOG-2, a co-factor of several GATA transcription factors (GATA-4, -5 and 6, is a critical regulator of coronary vessel formation and heart morphogenesis. Here we demonstrate that FOG-2 is SUMOylated and that this modification modulates its transcriptional activity. FOG-2 SUMOylation occurs at four lysine residues (K324, 471, 915, 955 [corrected]. Three of these residues are part of the characteristic SUMO consensus site (ψKXE, while K955 is found in the less frequent TKXE motif. Absence of SUMOylation did not affect FOG-2's nuclear localization. However, mutation of the FOG-2 SUMOylation sites, or de-SUMOylation, with SENP-1 or SENP-8 resulted in stronger transcriptional repression activity in both heterologous cells and cardiomyocytes. Conversely, increased FOG-2 SUMOylation by overexpression of SUMO-1 or expression of a SUMO-1-FOG-2 fusion protein rendered FOG-2 incapable of repressing GATA-4-mediated activation of the B-type natriuretic peptide (BNP promoter. Moreover, we demonstrate both increased interaction between a FOG-2 SUMO mutant and GATA-4 and enhanced SUMOylation of wild-type FOG-2 by co-expression of GATA-4. These data suggest a new dynamics in which GATA-4 may alter the activity of FOG-2 by influencing its SUMOylation status.

Airfoil design: Finding the balance between design lift and structural stiffness

International Nuclear Information System (INIS)

Bak, Christian; Gaudern, Nicholas; Zahle, Frederik; Vronsky, Tomas

2014-01-01

When upscaling wind turbine blades there is an increasing need for high levels of structural efficiency. In this paper the relationships between the aerodynamic characteristics; design lift and lift-drag ratio; and the structural characteristics were investigated. Using a unified optimization setup, airfoils were designed with relative thicknesses between 18% and 36%, a structural box height of 85% of the relative thickness, and varying box widths in chordwise direction between 20% and 40% of the chord length. The results from these airfoil designs showed that for a given flapwise stiffness, the design lift coefficient increases if the box length reduces and at the same time the relative thickness increases. Even though the conclusions are specific to the airfoil design approach used, the study indicated that an increased design lift required slightly higher relative thickness compared to airfoils with lower design lift to maintain the flapwise stiffness. Also, the study indicated that the lift-drag ratio as a function of flapwise stiffness was relatively independent of the airfoil design with a tendency that the lift-drag ratio decreased for large box lengths. The above conclusions were supported by an analysis of the three airfoil families Riso-C2, DU and FFA, where the lift-drag ratio as a function of flapwise stiffness was decreasing, but relatively independent of the airfoil design, and the design lift coefficient was varying depending on the design philosophy. To make the analysis complete also design lift and lift- drag ratio as a function of edgewise and torsional stiffness were shown

Observations of radiation fog chemistry in the Eastern United States

Science.gov (United States)

Straub, D.; Hutchings, J.; Herckes, P.

2010-07-01

The chemical composition of radiation fog in the Mid-Atlantic region of the United States has been the focus of an ongoing field campaign based in Selinsgrove, PA. This field study was established to provide a long term record that can be used to identify the effects of meteorology and air mass source regions on fog composition and to shed light on the role that fog can play in the production of secondary inorganic and organic aerosol mass. In the United States, studies that focus on radiation fog have been relatively rare. For the most part, they have been limited geographically to the Central Valley of California, though individual studies have also been conducted in the Central United States and along the Texas-Louisiana Gulf Coast. Sample collection for the current study began during the fall of 2007. Through 2009, samples from 25 radiation fog events have been obtained. A Caltech Heated Rod Cloudwater Collector (CHRCC) having a Dp50 of approximately 8 microns was used to collect one fog sample per event. Samples were typically collected between 2:00 AM and 7:00 AM under conditions of light winds, clear skies, and recent rainfall. Sample volumes ranged from 2.9 ml to 150 ml. Following collection, samples were analyzed for pH and then one of the following: major inorganic ions, dissolved total organic carbon, N-nitrosodimethylamine (NDMA), metals, or organic speciation. Through 2009, sample pH varied between 4.28 and 6.86 and averaged 5.03 based on H+ concentration. Ammonium and sulfate were found to be the most abundant ionic species in the fog samples. Sufficient ammonium was detected in nearly every sample to fully neutralize nitrate and sulfate. The concentrations of sulfate, nitrate, and ammonium observed in this study were lower than values reported in the literature for most other cloud and fog studies conducted in the US. Due to significant ammonium input, pH in the current study was higher than most other studies. Concentrations of total organic carbon

Motor of Lift RSG-GAS Performance Analysis after Repair

International Nuclear Information System (INIS)

Asep-Saepuloh; Yayan-Andriyanto; Yuyut-Suraniyanto

2006-01-01

The out of order an equipment is ordinary natural process happened, above all the equipment be used continually with very old time, as for as out of order can be resulted from kinds of cause. Lift motor out of order can be result by motor is broken or happened the body shorten then affected do not function it the lift, so until done rewinding process. The rewinding is furl to repeat at motor coils. Motor of Lift represent main activator machine turning around shares pulley. Lift Motor will work if there is called in normal operation condition or the moment manual switch if done maintenance. Motor used at lift is motor three phases with two speeds that is low speed and high speed. Rewinding process must be done removed the motor from Lift machine and have to be done by professional workshop. In during function test take place, temperature at coil reach 70 o C (exceeding boundary permitted). After done installation addition thermal at motor coil hence his temperature become normal that is only reach 50 o C. (author)

Characterization of Oscillatory Lift in MFC Airfoils

OpenAIRE

Lang Jr, Joseph Reagle

2014-01-01

The purpose of this research is to characterize the response of an airfoil with an oscillatory morphing, Macro-fiber composite (MFC) trailing edge. Correlation of the airfoil lift with the oscillatory input is presented. Modal analysis of the test airfoil and apparatus is used to determine the frequency response function. The effects of static MFC inputs on the FRF are presented and compared to the unactuated airfoil. The transfer function is then used to determine the lift component du...

Intrusion Detection System Based on Decision Tree over Big Data in Fog Environment

Directory of Open Access Journals (Sweden)

Kai Peng

2018-01-01

Full Text Available Fog computing, as the supplement of cloud computing, can provide low-latency services between mobile users and the cloud. However, fog devices may encounter security challenges as a result of the fog nodes being close to the end users and having limited computing ability. Traditional network attacks may destroy the system of fog nodes. Intrusion detection system (IDS is a proactive security protection technology and can be used in the fog environment. Although IDS in tradition network has been well investigated, unfortunately directly using them in the fog environment may be inappropriate. Fog nodes produce massive amounts of data at all times, and, thus, enabling an IDS system over big data in the fog environment is of paramount importance. In this study, we propose an IDS system based on decision tree. Firstly, we propose a preprocessing algorithm to digitize the strings in the given dataset and then normalize the whole data, to ensure the quality of the input data so as to improve the efficiency of detection. Secondly, we use decision tree method for our IDS system, and then we compare this method with Naïve Bayesian method as well as KNN method. Both the 10% dataset and the full dataset are tested. Our proposed method not only completely detects four kinds of attacks but also enables the detection of twenty-two kinds of attacks. The experimental results show that our IDS system is effective and precise. Above all, our IDS system can be used in fog computing environment over big data.

Normalized lift: an energy interpretation of the lift coefficient simplifies comparisons of the lifting ability of rotating and flapping surfaces.

Science.gov (United States)

Burgers, Phillip; Alexander, David E

2012-01-01

For a century, researchers have used the standard lift coefficient C(L) to evaluate the lift, L, generated by fixed wings over an area S against dynamic pressure, ½ρv(2), where v is the effective velocity of the wing. Because the lift coefficient was developed initially for fixed wings in steady flow, its application to other lifting systems requires either simplifying assumptions or complex adjustments as is the case for flapping wings and rotating cylinders.This paper interprets the standard lift coefficient of a fixed wing slightly differently, as the work exerted by the wing on the surrounding flow field (L/ρ·S), compared against the total kinetic energy required for generating said lift, ½v(2). This reinterpreted coefficient, the normalized lift, is derived from the work-energy theorem and compares the lifting capabilities of dissimilar lift systems on a similar energy footing. The normalized lift is the same as the standard lift coefficient for fixed wings, but differs for wings with more complex motions; it also accounts for such complex motions explicitly and without complex modifications or adjustments. We compare the normalized lift with the previously-reported values of lift coefficient for a rotating cylinder in Magnus effect, a bat during hovering and forward flight, and a hovering dipteran.The maximum standard lift coefficient for a fixed wing without flaps in steady flow is around 1.5, yet for a rotating cylinder it may exceed 9.0, a value that implies that a rotating cylinder generates nearly 6 times the maximum lift of a wing. The maximum normalized lift for a rotating cylinder is 1.5. We suggest that the normalized lift can be used to evaluate propellers, rotors, flapping wings of animals and micro air vehicles, and underwater thrust-generating fins in the same way the lift coefficient is currently used to evaluate fixed wings.

Variable Lifting Index (VLI): A New Method for Evaluating Variable Lifting Tasks.

Science.gov (United States)

Waters, Thomas; Occhipinti, Enrico; Colombini, Daniela; Alvarez-Casado, Enrique; Fox, Robert

2016-08-01

We seek to develop a new approach for analyzing the physical demands of highly variable lifting tasks through an adaptation of the Revised NIOSH (National Institute for Occupational Safety and Health) Lifting Equation (RNLE) into a Variable Lifting Index (VLI). There are many jobs that contain individual lifts that vary from lift to lift due to the task requirements. The NIOSH Lifting Equation is not suitable in its present form to analyze variable lifting tasks. In extending the prior work on the VLI, two procedures are presented to allow users to analyze variable lifting tasks. One approach involves the sampling of lifting tasks performed by a worker over a shift and the calculation of the Frequency Independent Lift Index (FILI) for each sampled lift and the aggregation of the FILI values into six categories. The Composite Lift Index (CLI) equation is used with lifting index (LI) category frequency data to calculate the VLI. The second approach employs a detailed systematic collection of lifting task data from production and/or organizational sources. The data are organized into simplified task parameter categories and further aggregated into six FILI categories, which also use the CLI equation to calculate the VLI. The two procedures will allow practitioners to systematically employ the VLI method to a variety of work situations where highly variable lifting tasks are performed. The scientific basis for the VLI procedure is similar to that for the CLI originally presented by NIOSH; however, the VLI method remains to be validated. The VLI method allows an analyst to assess highly variable manual lifting jobs in which the task characteristics vary from lift to lift during a shift. © 2015, Human Factors and Ergonomics Society.

The lightning striking probability for offshore wind turbine blade with salt fog contamination

Science.gov (United States)

Li, Qingmin; Ma, Yufei; Guo, Zixin; Ren, Hanwen; Wang, Guozheng; Arif, Waqas; Fang, Zhiyang; Siew, Wah Hoon

2017-08-01

The blades of an offshore wind turbine are prone to be adhered with salt fog after long-time exposure in the marine-atmosphere environment, and salt fog reduces the efficiency of the lightning protection system. In order to study the influence of salt fog on lightning striking probability (LSP), the lightning discharge process model for the wind turbine blade is adopted in this paper considering the accumulation mechanism of surface charges around the salt fog area. The distribution of potential and electric field with the development of the downward leader is calculated by COMSOL Multiphysics LiveLink for MATLAB. A quantitative characterization method is established to calculate the LSP base on the average electric field before the return stroke and the LSP distribution of the blade is shown in the form of a graphic view. The simulation results indicate that the receptor and conductor area close to the receptor area are more likely to get struck by lightning, and the LSP increases under the influence of salt fog. The validity of the model is verified by experiments. Furthermore, the receptor can protect the blade from lightning strikes effectively when the lateral distance between the rod electrode and receptor is short. The influence of salt fog on LSP is more obvious if salt fog is close to the receptor or if the scope of salt fog area increases.

1995 Integrated Monitoring Study: Fog measurements in the Southern San Joaquin Valley - preliminary results

Energy Technology Data Exchange (ETDEWEB)

Collett, J. Jr.; Bator, A.; Sherman, D.E. [Colorado State Univ., Fort Collins, CO (United States)] [and others

1996-12-31

Fogs were sampled at three ground-based stations in the southern portion of California`s San Joaquin Valley as part of the winter component of the 1995 Integrated Monitoring Study (IMS95). The three sampling sites included two urban locations (Bakersfield and Fresno) and one rural location (near the Kern Wildlife Refuge). Both bulk and drop size-fractionated samples were collected at each site. Several fog events were sampled, with three periods of extensive fog coverage that included all three sampling sites. Results of preliminary data analysis are presented. Fog collected at the sites was generally quite basic. Most bulk fog samples had pH values above 6 reflecting strong inputs from ammonia. Occasional strong sulfur plumes at Bakersfield, however, tended to lower the fog pH. Aside from these periods, nitrate was generally present at much higher concentrations in the fog than sulfate. Decreases in fogwater loadings of major species over the course of one extended fog episode at Fresno suggest significant deposition was occurring to the surface, consistent with observations of substantial droplet fluxes to exposed surfaces during that period. 16 refs., 7 figs., 1 tab.

Numerical Simulations of an Inversion Fog Event in the Salt Lake Valley during the MATERHORN-Fog Field Campaign

Science.gov (United States)

Chachere, Catherine N.; Pu, Zhaoxia

2018-01-01

An advanced research version of the Weather Research and Forecasting (WRF) Model is employed to simulate a wintertime inversion fog event in the Salt Lake Valley during the Mountain Terrain Atmospheric Modeling and Observations Program (MATERHORN) field campaign during January 2015. Simulation results are compared to observations obtained from the field program. The sensitivity of numerical simulations to available cloud microphysical (CM), planetary boundary layer (PBL), radiation, and land surface models (LSMs) is evaluated. The influence of differing visibility algorithms and initialization times on simulation results is also examined. Results indicate that the numerical simulations of the fog event are sensitive to the choice of CM, PBL, radiation, and LSM as well as the visibility algorithm and initialization time. Although the majority of experiments accurately captured the synoptic setup environment, errors were found in most experiments within the boundary layer, specifically a 3° warm bias in simulated surface temperatures compared to observations. Accurate representation of surface and boundary layer variables are vital in correctly predicting fog in the numerical model.

Hydrologic Effects and Biogeographic Impacts of Coastal Fog, Channel Islands, California

Science.gov (United States)

Fischer, D. T.; Still, C. J.; Williams, A. P.

2006-12-01

Fog has long been recognized as an important component of the hydrological cycle in many ecosystems, including coastal desert fog belts, tropical cloud forests, and montane areas worldwide. Fog drip can be a major source of water, particularly during the dry season, and there is evidence in some ecosystems of direct fogwater uptake by foliar absorption. Fog and low clouds can also increase availability of water by reducing evaporative water losses. In the California Channel Islands, fog and low stratus clouds dramatically affect the water budget of coastal vegetation, particularly during the long summer drought. This work focuses on a population of Bishop pine (Pinus muricata D. Don) on Santa Cruz Island. This is the southernmost large stand of this species, and tree growth and survival appears to be strongly limited by water availability. We have used parallel measurement and modeling approaches to quantify the importance of fogwater inputs and persistent cloud cover to Bishop pine growth. We have modeled drought stress over the last century based on local climate records, calibrated against a dense network of 12 weather stations on a 7km coastal-inland elevation gradient. Water availability is highly variable year to year, with episodic droughts that are associated with widespread tree mortality. Frequent cloud cover near the coast reduces evapotranspiration relative to the inland site (on the order of 25%), thereby delaying the onset of, and moderating the severity of the annual summer drought. Substantial summer fog drip at higher elevations provides additional water inputs that also reduce drought severity. Beyond the theoretical availability of extra water from fog drip, tree ring analysis and xylem water isotopic data suggest that significant amounts of fog water are actually taken up by these trees. Stand boundaries appear to be driven by spatial patterns of mortality related to water availability and frequency of severe drought. These results suggest that

Daytime sea fog retrieval based on GOCI data: a case study over the Yellow Sea.

Science.gov (United States)

Yuan, Yibo; Qiu, Zhongfeng; Sun, Deyong; Wang, Shengqiang; Yue, Xiaoyuan

2016-01-25

In this paper, a new daytime sea fog detection algorithm has been developed by using Geostationary Ocean Color Imager (GOCI) data. Based on spectral analysis, differences in spectral characteristics were found over different underlying surfaces, which include land, sea, middle/high level clouds, stratus clouds and sea fog. Statistical analysis showed that the Rrc (412 nm) (Rayleigh Corrected Reflectance) of sea fog pixels is approximately 0.1-0.6. Similarly, various band combinations could be used to separate different surfaces. Therefore, three indices (SLDI, MCDI and BSI) were set to discern land/sea, middle/high level clouds and fog/stratus clouds, respectively, from which it was generally easy to extract fog pixels. The remote sensing algorithm was verified using coastal sounding data, which demonstrated that the algorithm had the ability to detect sea fog. The algorithm was then used to monitor an 8-hour sea fog event and the results were consistent with observational data from buoys data deployed near the Sheyang coast (121°E, 34°N). The goal of this study was to establish a daytime sea fog detection algorithm based on GOCI data, which shows promise for detecting fog separately from stratus.

Heat transfer from a high temperature condensable mixture. II. Sedimentation of fog condensate

International Nuclear Information System (INIS)

Condiff, D.W.; Cho, D.H.; Chan, S.H.

1985-01-01

A kinematic wave analysis of fog sedimentation is employed to relate growth of a fog condensate deposit layer to radiation generated fog formation rates. The increase of surface radiation absorptivity with deposit layer thickness promotes a feedback mechanism for higher growth rates, which is evaluated in detail

Changes in spine loading patterns throughout the workday as a function of experience, lift frequency, and personality.

Science.gov (United States)

Chany, Anne-Marie; Parakkat, Julia; Yang, Gang; Burr, Deborah L; Marras, William S

2006-01-01

Psychosocial stressors have been associated with low back pain reporting. However, response to psychosocial risk factors may be dependent on the individual's personality type that, in turn, can affect muscle recruitment and spine loading. This study explores how personality might be associated with spine loading during repetitive lifting performed throughout an entire work shift. Assess spine loading as a function of an individual's personality type during repetitive, long-term exposure to a materials handling tasks. Laboratory experiment where experienced and inexperienced participants performed repetitive, asymmetric lifts at various load and lift frequency levels throughout a series of 8-hour exposure periods. Spine loads were monitored throughout the work period. Twelve novice and 12 experienced materials handlers who were asymptomatic for back pain. Spine compression, anterior-posterior (A/P) shear, and lateral shear at the L5-S1 level. Participants were categorized into personality types based upon the Myers-Briggs personality type indicator. An electromyography-assisted biomechanical model was used to assess spine compression, A/P shear, and lateral shear throughout the exposure period. The results indicate that intuitors had higher shear spinal loading regardless of moment exposure, lift frequency, and time through the work period, compared with the sensor personality type. In addition, higher spine compressive and shear forces occurred in the perceiver personality compared with the judgers' personality trait, regardless of moment and, often, lift frequency. Novice lifters typically experienced greater spine loading. The results suggest that when there exists a personality-job environment mismatch, spinal loading increases via an increase in antagonistic co-contraction. The trends suggest that inherent personality characteristics may play a role in one's motor control strategies when performing a repetitive lifting task.

Thermally Optimized Polarization-Maintaining Photonic Crystal Fiber and Its FOG Application.

Science.gov (United States)

Zhang, Chunxi; Zhang, Zhihao; Xu, Xiaobin; Cai, Wei

2018-02-13

In this paper, we propose a small-diameter polarization-maintaining solid-core photonic crystal fiber. The coating diameter, cladding diameter and other key parameters relating to the thermal properties were studied. Based on the optimized parameters, a fiber with a Shupe constant 15% lower than commercial photonic crystal fibers (PCFs) was fabricated, and the transmission loss was lower than 2 dB/km. The superior thermal stability of our fiber design was proven through both simulation and measurement. Using the small-diameter fiber, a split high precision fiber optic gyro (FOG) prototype was fabricated. The bias stability of the FOG was 0.0023 °/h, the random walk was 0.0003 °/ h , and the scale factor error was less than 1 ppm. Throughout a temperature variation ranging from -40 to 60 °C, the bias stability was less than 0.02 °/h without temperature compensation which is notably better than FOG with panda fiber. As a result, the PCF FOG is a promising choice for high precision FOG applications.

Benefit of infrared images in visibility appreciation for fog conditions

Science.gov (United States)

Boucher, V.; Dumoulin, J.; Marchetti, M.

2012-04-01

Fog situations induce an increase in both accident probability and severity. They constitue a significant part in accident rate. There is very few means to forecast fog, nor to appreciate its density, and its associated visibility decrease. An approach consists in developing on-board tools to qualify and to quantify the fog, and to improve the visibility within each vehicle. Infrared technology is now more common, so solutions based on this specific spectral band could be considered. LW infrared has demonstrated its value in the case of passenger cars. Its use could be discussed too, in particular in the case of obstacles detection. The study presented here deals mainly with the extraction of a visbility distance from LW thermal images in the presence of fog. A French facility in Clermont-Ferrand allows the generation of fog. It can be generated in day or night conditions. The facility is 30 m long, for a 220 m3 volume. The fog is generated spraying water micro droplets, which size is controlled and measured. Experimental conditions could be adapted through water pressure, water nature as an example. Visibility is appreciated with a device measuring light transmission. In the case of infrared, visibility is obtained through the definition of contrast of an object on a given background. On such a basis, infrared spectral band provides a factor 2 benefit on a conventional roadsign, and of a factor 4 in the case of a heated one, with meteorological visibilty of 20 m. Some theoritical aspects will be described, along with a description of the whole experimental setup.

Inactivation of stable viruses in cell culture facilities by peracetic acid fogging.

Science.gov (United States)

Gregersen, Jens-Peter; Roth, Bernhard

2012-07-01

Looking for a robust and simple method to replace formaldehyde fumigation for the disinfection of virus-handling laboratories and facilities, we tested peracetic acid fogging as a method to inactivate stable viruses under practical conditions. Peracetic acid/hydrogen peroxide (5.8%/27.5%, 2.0 mL/m³) was diluted in sufficient water to achieve ≥ 70% relative humidity and was vaporized as peracetic acid fog in various positions in the laboratory. After vaporization, a 60 min exposure time, and venting of the laboratory, no residual virus was detected on any of the carriers (detection limit disinfection runs within 12 months, no damage or functional impairment of electrical and electronic equipment was noted. Copyright © 2012 The International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved.

Normalized Lift: An Energy Interpretation of the Lift Coefficient Simplifies Comparisons of the Lifting Ability of Rotating and Flapping Surfaces

Science.gov (United States)

Burgers, Phillip; Alexander, David E.

2012-01-01

For a century, researchers have used the standard lift coefficient CL to evaluate the lift, L, generated by fixed wings over an area S against dynamic pressure, ½ρv 2, where v is the effective velocity of the wing. Because the lift coefficient was developed initially for fixed wings in steady flow, its application to other lifting systems requires either simplifying assumptions or complex adjustments as is the case for flapping wings and rotating cylinders. This paper interprets the standard lift coefficient of a fixed wing slightly differently, as the work exerted by the wing on the surrounding flow field (L/ρ·S), compared against the total kinetic energy required for generating said lift, ½v2. This reinterpreted coefficient, the normalized lift, is derived from the work-energy theorem and compares the lifting capabilities of dissimilar lift systems on a similar energy footing. The normalized lift is the same as the standard lift coefficient for fixed wings, but differs for wings with more complex motions; it also accounts for such complex motions explicitly and without complex modifications or adjustments. We compare the normalized lift with the previously-reported values of lift coefficient for a rotating cylinder in Magnus effect, a bat during hovering and forward flight, and a hovering dipteran. The maximum standard lift coefficient for a fixed wing without flaps in steady flow is around 1.5, yet for a rotating cylinder it may exceed 9.0, a value that implies that a rotating cylinder generates nearly 6 times the maximum lift of a wing. The maximum normalized lift for a rotating cylinder is 1.5. We suggest that the normalized lift can be used to evaluate propellers, rotors, flapping wings of animals and micro air vehicles, and underwater thrust-generating fins in the same way the lift coefficient is currently used to evaluate fixed wings. PMID:22629326

Normalized lift: an energy interpretation of the lift coefficient simplifies comparisons of the lifting ability of rotating and flapping surfaces.

Directory of Open Access Journals (Sweden)

Phillip Burgers

Full Text Available For a century, researchers have used the standard lift coefficient C(L to evaluate the lift, L, generated by fixed wings over an area S against dynamic pressure, ½ρv(2, where v is the effective velocity of the wing. Because the lift coefficient was developed initially for fixed wings in steady flow, its application to other lifting systems requires either simplifying assumptions or complex adjustments as is the case for flapping wings and rotating cylinders.This paper interprets the standard lift coefficient of a fixed wing slightly differently, as the work exerted by the wing on the surrounding flow field (L/ρ·S, compared against the total kinetic energy required for generating said lift, ½v(2. This reinterpreted coefficient, the normalized lift, is derived from the work-energy theorem and compares the lifting capabilities of dissimilar lift systems on a similar energy footing. The normalized lift is the same as the standard lift coefficient for fixed wings, but differs for wings with more complex motions; it also accounts for such complex motions explicitly and without complex modifications or adjustments. We compare the normalized lift with the previously-reported values of lift coefficient for a rotating cylinder in Magnus effect, a bat during hovering and forward flight, and a hovering dipteran.The maximum standard lift coefficient for a fixed wing without flaps in steady flow is around 1.5, yet for a rotating cylinder it may exceed 9.0, a value that implies that a rotating cylinder generates nearly 6 times the maximum lift of a wing. The maximum normalized lift for a rotating cylinder is 1.5. We suggest that the normalized lift can be used to evaluate propellers, rotors, flapping wings of animals and micro air vehicles, and underwater thrust-generating fins in the same way the lift coefficient is currently used to evaluate fixed wings.

Frequency of fog in midlands of England

Energy Technology Data Exchange (ETDEWEB)

Unsworth, M.H.; Shakespeare, N.W.; Milner, A.E.; Ganendra, T.S.

1979-01-01

A survey shows that at a rural site in the Trent Basin in England, there has been a considerable reduction in winter fog frequency in the last 20 years. The evidence suggests that the Clean Air Act, which was primarily designed to improve air quality in towns has also produced measurable decreases in fog frequency in rural parts of this industrial region. The mechanism which is believed to underly the phenomenon is that the number of condensation nuclei have been substantially reduced. 9 references, 4 figures, 1 table.

Effect of heat transfer in the fog region during core reflooding

International Nuclear Information System (INIS)

Rouai, N. M.; El-sawy, H. M.

1993-01-01

Core reflooding following a loss of coolant accident (LOCA) in a pressurized water reactor (PWR) received considerable attention during the past thirty years. In this paper a one dimensional model is used to study the effect of the heat transfer in the fog region ahead of the wet front reflooding rate of a cylindrical fuel element following a LOCA in a PWR. The heat conduction equation in the cladding is solved in coordinate system moving with the wet front under a variety of condition to investigate the effects of such parameters as the initial cladding surface temperature, the decay heat generation rate in the fuel and the mode of heat transfer prevailing. The cladding surface is divided into three axial regions according to the mechanism of heat transfer, namely, a boiling region behind the wet front, a fog region ahead of the wet front and a dry region further downstream of the wet front. The effect of changing the heat transfer coefficient in the fog region on the rewetting rate and on the fog length is investigated. The results of this simple model show that increasing the heat transfer in the fog region increases the rewetting velocity and consequently decreases the fog length. The results are in general agreement with a more accurate two-dimensional model and experimental data. (author)

Analysis of fog effects on terrestrial Free Space optical communication links

KAUST Repository

Esmail, Maged Abdullah

2016-07-26

In this paper, we consider and examine fog measurement data, coming from several locations in Europe and USA, and attempt to derive a unified model for fog attenuation in free space optics (FSO) communication links. We evaluate and compare the performance of our proposed model to that of many well-known alternative models. We found that our proposed model, achieves an average RMSE that outperforms them by more than 9 dB. Furthermore, we have studied the performance of the FSO system using different performance metrics such as signal-to-noise (SNR) ratio, bit error rate (BER), and channel capacity. Our results show that FSO is a short range technology. Therefore, FSO is expected to find its place in future networks that will have small cell size, i.e., <1 km diameter. Moreover, our investigation shows that under dense fog, it is difficult to maintain a communications link because of the high signal attenuation, which requires switching the communications to RF backup. Our results show that increasing the transmitted power will improve the system performance under light fog. However, under heavy fog, the effect is minor. To enhance the system performance under low visibility range, multi-hop link is used which can enhance the power budget by using short segments links. Using 22 dBm transmitted power, we obtained BER=10-3 over 1 km link length with 600 m visibility range which corresponds to light fog. However, under lower visibility range equals 40 m that corresponds to dense fog, we obtained the same BER but over 200 m link length. © 2016 IEEE.

Asymmetric ratchet effect for directional transport of fog drops on static and dynamic butterfly wings.

Science.gov (United States)

Liu, Chengcheng; Ju, Jie; Zheng, Yongmei; Jiang, Lei

2014-02-25

Inspired by novel creatures, researchers have developed varieties of fog drop transport systems and made significant contributions to the fields of heat transferring, water collecting, antifogging, and so on. Up to now, most of the efforts in directional fog drop transport have been focused on static surfaces. Considering it is not practical to keep surfaces still all the time in reality, conducting investigations on surfaces that can transport fog drops in both static and dynamic states has become more and more important. Here we report the wings of Morpho deidamia butterflies can directionally transport fog drops in both static and dynamic states. This directional drop transport ability results from the micro/nano ratchet-like structure of butterfly wings: the surface of butterfly wings is composed of overlapped scales, and the scales are covered with porous asymmetric ridges. Influenced by this special structure, fog drops on static wings are transported directionally as a result of the fog drops' asymmetric growth and coalescence. Fog drops on vibrating wings are propelled directionally due to the fog drops' asymmetric dewetting from the wings.

1995 Integrated Monitoring Study: Fog measurements in the Northern San Joaquin Valley - preliminary results

Energy Technology Data Exchange (ETDEWEB)

Collett, J. Jr.; Bator, A.; Sherman, D.E. [Colorado State Univ., Fort Collins, CO (United States)] [and others

1996-12-31

Vertical gradients in fog chemistry and physics were measured from a 430 m television broadcast tower in the northern San Joaquin Valley near Walnut Grove, California. Fog was collected on the ground and at two elevations on the tower using Caltech Active Strand Cloudwater Collectors Version 2 (CASCC2). Work was conducted as part of the 1995 Integrated Monitoring Study (IMS95). Results will be used to evaluate the need to make measurements aloft in future regional studies of fog processing of atmospheric particles and for testing whether vertically resolved fog models provide realistic simulations of fog physics and chemistry above the ground. Two fog/low cloud events were sampled during the tower study. Preliminary results show concentrations of major species in the fogwater typically decreasing with altitude, while liquid water contents increase. Fogwater loadings of major species, the total amount of a species in the aqueous phase per unit air volume, were observed to increase with altitude. Major species concentrations were typically quite stable at a given elevation, while significant decreases were observed over time in liquid water content. Fogwater concentrations of soluble hydroperoxides were highest near the surface and increased with time after sunrise and were observed to coexist in the high pH fog with S(IV). Time lapse video footage of the top of the fog/cloud layer revealed a very dynamic interface, suggesting entrainment of material from the clear air into the fog/cloud may be significant. 12 refs., 7 figs.

Numerical simulation of diurnally varying thermal environment in a street canyon under haze-fog conditions

Science.gov (United States)

Tan, Zijing; Dong, Jingliang; Xiao, Yimin; Tu, Jiyuan

2015-10-01

The impact of haze-fog on surface temperature, flow pattern, pollutant dispersion and pedestrian thermal comfort are investigated using computational fluid dynamics (CFD) approach based on a three-dimensional street canyon model under different haze-fog conditions. In this study, light extinction coefficient (Kex) is adopted to represent haze-fog pollution level. Numerical simulations are performed for different Kex values at four representative time events (1000 LST, 1300 LST, 1600 LST and 2000 LST). The numerical results suggest that the surface temperature is strongly affected by the haze-fog condition. Surface heating induced by the solar radiation is enhanced by haze-fog, as higher surface temperature is observed under thicker haze-fog condition. Moreover, the temperature difference between sunlit and shadow surfaces is reduced, while that for the two shadow surfaces is slightly increased. Therefore, the surface temperature among street canyon facets becomes more evenly distributed under heavy haze-fog conditions. In addition, flow patterns are considerably altered by different haze-fog conditions, especially for the afternoon (1600 LST) case, in which thermal-driven flow has opposite direction as that of the wind-driven flow direction. Consequently, pollutants such as vehicular emissions will accumulate at pedestrian level, and pedestrian thermal comfort may lower under thicker haze-fog condition.

Aerosol Number Concentrations and Visibility during Dense Fog over a Subtropical Urban Site

Directory of Open Access Journals (Sweden)

Manju Mohan

2014-01-01

Full Text Available There is now enough evidence of greater frequencies and extent of fog formation in urban areas. These could easily be linked to rapid increase in aerosol number concentration (ANC peculiar to polluted urban environments. It is therefore pertinent to study ANC and visibility alongside the meteorological parameters in order to investigate the relationships which may possibly exist between these parameters especially during foggy conditions. This study based on field measurements of ANC for aerosol spectrum varying from 0.3 µm to 20 µm attempts to investigates whether a threshold ANC could be associated with a given visibility range during low visibility conditions including dense fog episodes. Thus, the present work explores relationship between ANC size spectrum and visibility (100 m–4500 m in a polluted urban environment in India with specific reference to episodes of dense fog during winter period. The study depicts a threshold minimum value of ANC during foggy conditions. A power relationship between ANC and visibility is obtained. Further, aerosol number distribution and size distribution function are also studied and empirical relation is compared with previous studies. Further work is suggested to strengthen the findings presented here.

The Potential for Scaling Up a Fog Collection System on the Eastern Escarpment of Eritrea

Directory of Open Access Journals (Sweden)

Mussie Fessehaye

2015-11-01

Full Text Available Fog is an untapped natural resource. A number of studies have been undertaken to understand its potential as an alternative or complementary water source. In 2007, a pilot fog-collection project was implemented in 2 villages on the Eastern Escarpment of Eritrea. The government of Eritrea, buoyed by the project’s positive results, has encouraged research into and application of fog-collection technologies to alleviate water-supply problems in this region. In 2014, this study was undertaken to assess the coverage, prevalence, intensity, and seasonality of fog on the Eastern Escarpment of Eritrea and consequently to identify potential beneficiary villages. Three independent methods used in the study—satellite image analyses, personal interviews, and a standard fog collector—produced reasonably similar characterizations of fog coverage and timing. The period with high fog incidence is mainly between November and March, with the highest number of fog days per year (96 on the central Eastern Escarpment and decreasing frequency to the south (78 days and north (73 days. The fog intensity on the central Eastern Escarpment is very high and in most cases reduces visibility to less than 500 m. In this period, a light to moderate breeze blows predominantly from the north and northeast. More than half of the villages in the region currently have a reliable water-supply system. The rest depend on seasonal roof-water harvesting, rock-water harvesting, and truck delivery and, therefore, could potentially benefit from fog collection as a supplementary water source. In particular, fog water could be useful for a small number of beneficiaries, including public services like schools and health facilities, where conventional water-delivery systems are not viable.

Summer water use by California coastal prairie grasses: fog, drought, and community composition.

Science.gov (United States)

Corbin, Jeffrey D; Thomsen, Meredith A; Dawson, Todd E; D'Antonio, Carla M

2005-10-01

Plants in the Mediterranean climate region of California typically experience summer drought conditions, but correlations between zones of frequent coastal fog inundation and certain species' distributions suggest that water inputs from fog may influence species composition in coastal habitats. We sampled the stable H and O isotope ratios of water in non-photosynthetic plant tissue from a variety of perennial grass species and soil in four sites in northern California in order to determine the proportion of water deriving from winter rains and fog during the summer. The relationship between H and O stable isotopes from our sample sites fell to the right of the local meteoric water line (LMWL) during the summer drought, providing evidence that evaporation of water from the soil had taken place prior to the uptake of water by vegetation. We developed a novel method to infer the isotope values of water before it was subjected to evaporation in which we used experimental data to calculate the slope of the deltaH versus deltaO line versus the LMWL. After accounting for evaporation, we then used a two-source mixing model to evaluate plant usage of fog water. The model indicated that 28-66% of the water taken up by plants via roots during the summer drought came from fog rather than residual soil water from winter rain. Fog use decreased as distance from the coast increased, and there were significant differences among species in the use of fog. Rather than consistent differences in fog use by species whose distributions are limited to the coast versus those with broader distributions, species responded individualistically to summer fog. We conclude that fogwater inputs can mitigate the summer drought in coastal California for many species, likely giving an advantage to species that can use it over species that cannot.

Numerical simulations of an advection fog event over Shanghai Pudong International Airport with the WRF model

Science.gov (United States)

Lin, Caiyan; Zhang, Zhongfeng; Pu, Zhaoxia; Wang, Fengyun

2017-10-01

A series of numerical simulations is conducted to understand the formation, evolution, and dissipation of an advection fog event over Shanghai Pudong International Airport (ZSPD) with the Weather Research and Forecasting (WRF) model. Using the current operational settings at the Meteorological Center of East China Air Traffic Management Bureau, the WRF model successfully predicts the fog event at ZSPD. Additional numerical experiments are performed to examine the physical processes associated with the fog event. The results indicate that prediction of this particular fog event is sensitive to microphysical schemes for the time of fog dissipation but not for the time of fog onset. The simulated timing of the arrival and dissipation of the fog, as well as the cloud distribution, is substantially sensitive to the planetary boundary layer and radiation (both longwave and shortwave) processes. Moreover, varying forecast lead times also produces different simulation results for the fog event regarding its onset and duration, suggesting a trade-off between more accurate initial conditions and a proper forecast lead time that allows model physical processes to spin up adequately during the fog simulation. The overall outcomes from this study imply that the complexity of physical processes and their interactions within the WRF model during fog evolution and dissipation is a key area of future research.

Centrifugation-Assisted Fog-Collecting Abilities of Metal-Foam Structures with Different Surface Wettabilities.

Science.gov (United States)

Ji, Keju; Zhang, Jun; Chen, Jia; Meng, Guiyun; Ding, Yafei; Dai, Zhendong

2016-04-20

The collection of water from fog is a simple and sustainable means of obtaining freshwater for human and animal consumption. Herein, we address the use of metal foam in fog collection and present a novel fog-collecting device fabricated from copper foam. This device, which can also be used in other liquid-gas separation applications, is a 3D extension of biologically inspired 1D and 2D materials. The network structure of the 3D material effectively increased the contact area and interaction time of the skeleton structure and fog compared to those of traditional 2D fog-collecting materials. The main aspects investigated in this study were the influences of the inertial centrifugal force generated by rotating the metal-foam samples and the use of samples with different surface wettabilities on the fog-collecting performance. Superhydrophilic and superhydrophobic samples were found to have higher collection efficiencies at low and high rotational speeds, respectively, and a maximum efficiency of 86% was achieved for superhydrophobic copper foam (20 pores per inch) rotated at 1500 rpm.

Fog, cloud, and dew chemistry. Final report

Energy Technology Data Exchange (ETDEWEB)

Hoffmann, M.R.

1989-02-28

The spatial and temporal variations of fog/cloud chemistry were determined in the San Joaquin Valley, in the Los Angeles Basin, and in the Santa Barbara Channel area using automated fog- and cloudwater collectors that were designed and constructed for the project. A significant correlation was observed between the average nighttime cloud- and fogwater loadings of H/sup +/ and NO/sub 3//sup /minus// and the maximum levels of O/sub 3//sup /minus//. Higher aldehydes, a series of dicarbonyls, and a variety of sulfonic acid salts formed by reaction of S(IV) and aldehydes were quantitatively determined in the droplet phase.

Evaluation of physical and chemical properties and their interactions in fat, oil, and grease (FOG) deposits.

Science.gov (United States)

Gross, Martin A; Jensen, Jeanette L; Gracz, Hanna S; Dancer, Jens; Keener, Kevin M

2017-10-15

Fat, oil and grease (FOG) blockages in sewer systems are a substantial problem in the United States. It has been estimated that over 50% of sewer overflows are a result of FOG blockages. In this work, a thorough laboratory study was undertaken to examine key variables that contribute to FOG deposit formation under controlled conditions. Physical and chemical properties and their interactions were evaluated and conditions that generated deposits that mimicked field FOG deposits were identified. It was found that 96 of the of 128 reaction conditions tested in the laboratory formed FOG deposits with similar physical and chemical characteristics as field FOG deposits. It was also found that FOG deposits can be created through fatty acid crystallization and not just saponification. Furthermore FOG deposits were found to be more complex than previously documented and contain free fatty acids, fatty acid metal salts, triacylglycerol's, diacylglycerol's and, monoacylglycerol's. Lastly it was found that FOG deposits that only contained saturated fatty acids were on average 2.1 times higher yield strength than deposits that contained unsaturated fatty acids. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effect of medication and the role of postural instability in different components of freezing of gait (FOG).

Science.gov (United States)

Nantel, Julie; Bronte-Stewart, Helen

2014-04-01

Freezing of gait (FOG) is associated with gait asymmetry and arrhythmicity, cognitive impairment in Parkinson's disease (PD). However, the role of postural instability (PI) in and the effect of dopaminergic medication (meds) on FOG are unclear. We investigated the effect of meds on FOG using a validated metric, Stepping in Place (SIP) and the relationship between PI and FOG. We assessed static posturography (off meds), SIP, UPDRS-III (off/on meds) and the FOG-questionnaire (FOG-Q) in 15 freezers/15 non-freezers and 14 healthy controls. UPDRS-III, rigidity, tremor (P FOG-Q was correlated with CoP anteroposterior displacement and mediolateral VCoP (R = 0.42; R = 0.40, P FOG frequency and duration but not of gait asymmetry and arrhythmicity on meds suggests that both dopaminergic and non-dopaminergic networks contribute to FOG. The correlations between postural instability and FOG severity and SIP asymmetry on meds, suggest that as the disease progresses, postural instability interferes with gait symmetry and lead to on meds FOG and falls. Copyright © 2014 Elsevier Ltd. All rights reserved.

An analysis, sensitivity and prediction of winter fog events using FASP model over Indo-Gangetic plains, India

Science.gov (United States)

Srivastava, S. K., Sr.; Sharma, D. A.; Sachdeva, K.

2017-12-01

Indo-Gangetic plains of India experience severe fog conditions during the peak winter months of December and January every year. In this paper an attempt has been to analyze the spatial and temporal variability of winter fog over Indo-Gangetic plains. Further, an attempt has also been made to configure an efficient meso-scale numerical weather prediction model using different parameterization schemes and develop a forecasting tool for prediction of fog during winter months over Indo-Gangetic plains. The study revealed that an alarming increasing positive trend of fog frequency prevails over many locations of IGP. Hot spot and cluster analysis were conducted to identify the high fog prone zones using GIS and inferential statistical tools respectively. Hot spots on an average experiences fog on 68.27% days, it is followed by moderate and cold spots with 48.03% and 21.79% respectively. The study proposes a new FASP (Fog Analysis, sensitivity and prediction) Model for overall analysis and prediction of fog at a particular location and period over IGP. In the first phase of this model long term climatological fog data of a location is analyzed to determine its characteristics and prevailing trend using various advanced statistical techniques. During a second phase a sensitivity test is conducted with different combination of parameterization schemes to determine the most suitable combination for fog simulation over a particular location and period and in the third and final phase, first ARIMA model is used to predict the number of fog days in future . Thereafter, Numerical model is used to predict the various meteorological parameters favourable for fog forecast. Finally, Hybrid model is used for fog forecast over the study location. The results of the FASP model are validated with actual ground based fog data using statistical tools. Forecast Fog-gram generated using hybrid model during Jan 2017 shows highly encouraging results for fog occurrence/Non occurrence between

Outdoor FSO Communications Under Fog: Attenuation Modeling and Performance Evaluation

KAUST Repository

Esmail, Maged Abdullah

2016-07-18

Fog is considered to be a primary challenge for free space optics (FSO) systems. It may cause attenuation that is up to hundreds of decibels per kilometer. Hence, accurate modeling of fog attenuation will help telecommunication operators to engineer and appropriately manage their networks. In this paper, we examine fog measurement data coming from several locations in Europe and the United States and derive a unified channel attenuation model. Compared with existing attenuation models, our proposed model achieves a minimum of 9 dB, which is lower than the average root-mean-square error (RMSE). Moreover, we have investigated the statistical behavior of the channel and developed a probabilistic model under stochastic fog conditions. Furthermore, we studied the performance of the FSO system addressing various performance metrics, including signal-to-noise ratio (SNR), bit-error rate (BER), and channel capacity. Our results show that in communication environments with frequent fog, FSO is typically a short-range data transmission technology. Therefore, FSO will have its preferred market segment in future wireless fifth-generation/sixth-generation (5G/6G) networks having cell sizes that are lower than a 1-km diameter. Moreover, the results of our modeling and analysis can be applied in determining the switching/thresholding conditions in highly reliable hybrid FSO/radio-frequency (RF) networks.

A Secure and Privacy-Preserving Navigation Scheme Using Spatial Crowdsourcing in Fog-Based VANETs

Science.gov (United States)

Wang, Lingling; Liu, Guozhu; Sun, Lijun

2017-01-01

Fog-based VANETs (Vehicular ad hoc networks) is a new paradigm of vehicular ad hoc networks with the advantages of both vehicular cloud and fog computing. Real-time navigation schemes based on fog-based VANETs can promote the scheme performance efficiently. In this paper, we propose a secure and privacy-preserving navigation scheme by using vehicular spatial crowdsourcing based on fog-based VANETs. Fog nodes are used to generate and release the crowdsourcing tasks, and cooperatively find the optimal route according to the real-time traffic information collected by vehicles in their coverage areas. Meanwhile, the vehicle performing the crowdsourcing task can get a reasonable reward. The querying vehicle can retrieve the navigation results from each fog node successively when entering its coverage area, and follow the optimal route to the next fog node until it reaches the desired destination. Our scheme fulfills the security and privacy requirements of authentication, confidentiality and conditional privacy preservation. Some cryptographic primitives, including the Elgamal encryption algorithm, AES, randomized anonymous credentials and group signatures, are adopted to achieve this goal. Finally, we analyze the security and the efficiency of the proposed scheme. PMID:28338620

A Secure and Privacy-Preserving Navigation Scheme Using Spatial Crowdsourcing in Fog-Based VANETs.

Science.gov (United States)

Wang, Lingling; Liu, Guozhu; Sun, Lijun

2017-03-24

Fog-based VANETs (Vehicular ad hoc networks) is a new paradigm of vehicular ad hoc networks with the advantages of both vehicular cloud and fog computing. Real-time navigation schemes based on fog-based VANETs can promote the scheme performance efficiently. In this paper, we propose a secure and privacy-preserving navigation scheme by using vehicular spatial crowdsourcing based on fog-based VANETs. Fog nodes are used to generate and release the crowdsourcing tasks, and cooperatively find the optimal route according to the real-time traffic information collected by vehicles in their coverage areas. Meanwhile, the vehicle performing the crowdsourcing task can get a reasonable reward. The querying vehicle can retrieve the navigation results from each fog node successively when entering its coverage area, and follow the optimal route to the next fog node until it reaches the desired destination. Our scheme fulfills the security and privacy requirements of authentication, confidentiality and conditional privacy preservation. Some cryptographic primitives, including the Elgamal encryption algorithm, AES, randomized anonymous credentials and group signatures, are adopted to achieve this goal. Finally, we analyze the security and the efficiency of the proposed scheme.

Fog Collection on Polyethylene Terephthalate (PET) Fibers: Influence of Cross Section and Surface Structure.

Science.gov (United States)

Azad, M A K; Krause, Tobias; Danter, Leon; Baars, Albert; Koch, Kerstin; Barthlott, Wilhelm

2017-06-06

Fog-collecting meshes show a great potential in ensuring the availability of a supply of sustainable freshwater in certain arid regions. In most cases, the meshes are made of hydrophilic smooth fibers. Based on the study of plant surfaces, we analyzed the fog collection using various polyethylene terephthalate (PET) fibers with different cross sections and surface structures with the aim of developing optimized biomimetic fog collectors. Water droplet movement and the onset of dripping from fiber samples were compared. Fibers with round, oval, and rectangular cross sections with round edges showed higher fog-collection performance than those with other cross sections. However, other parameters, for example, width, surface structure, wettability, and so forth, also influenced the performance. The directional delivery of the collected fog droplets by wavy/v-shaped microgrooves on the surface of the fibers enhances the formation of a water film and their fog collection. A numerical simulation of the water droplet spreading behavior strongly supports these findings. Therefore, our study suggests the use of fibers with a round cross section, a microgrooved surface, and an optimized width for an efficient fog collection.

Durable anti-fogging effect and adhesion improvement on polymer surfaces

Science.gov (United States)

Moser, E. M.; Gilliéron, D.; Henrion, G.

2010-01-01

The hydrophobic properties of polymeric surfaces may cause fogging in transparent packaging and poor adhesion to printing colours and coatings. Novel plasma processes for durable functionalization of polypropylene and polyethylene terephthalate substrates were developed and analysed using optical emission spectroscopy. A worm-like nano pattern was created on the polypropylene surface prior to the deposition of thin polar plasma polymerised layers. For both substrates, highly polar surfaces exhibiting a surface tension of up to 69 mN/m and a water contact angle of about 10° were produced - providing the anti-fogging effect. The deposition of thin plasma polymerised layers protects the increased surface areas and enables to tailoring the surface energy of the substrate in a wide range. Wetting characteristics were determined by dynamic contact angle measurements. Investigations of the chemical composition of several layers using X-ray photoelectron spectroscopy and FT-infrared spectroscopy were correlated with functional testing. The surface topography was investigated using atomic force microscopy. The weldability and peeling-off characteristics of the plasma treated polymer films could be adjusted by varying the process parameters. Global and specific migration analyses were undertaken in order to ensure the manufacturing of plasma treated polymer surfaces for direct food contact purposes.

Fog deposition fluxes of water and ions to a mountainous site in Central Europe

OpenAIRE

Klemm, Otto; Wrzesinsky, Thomas

2011-01-01

Fog and precipitation composition and deposition were measured over a 1-yr period. Ion concentrations were higher in fog than in precipitation by factors of between 6 and 18. The causes of these differences were less dilution of fog water due to non-availability of condensable water vapour, and more efficient transfer of surface emissions to fog water as compared to rain water or snow. Fogwater and dissolved ions depositions were measured with eddy covariance in combination with a bulk fogwat...

Study on process design of partially-balanced, hydraulically lifting vertical ship lift

Science.gov (United States)

Xin, Shen; Xiaofeng, Xu; Lu, Zhang; Bing, Zhu; Fei, Li

2017-11-01

The hub ship lift in Panjin is the first navigation structure in China for the link between the inland and open seas, which adopts a novel partially-balanced, hydraulically lifting ship lift; it can meet such requirements as fast and sharp water level change in open sea, large draft of a yacht, and launching of a ship reception chamber; its balancing weight system can effectively reduce the load of the primary lifting cylinder, and optimize the force distribution of the ship reception chamber. The paper provides an introduction to main equipment, basic principles, main features and system composition of a ship lift. The unique power system and balancing system of the completed ship lift has offered some experience for the construction of the tourism-type ship lifts with a lower lifting height.

Fog tests performed at Kennedy Space Center on Kodak film type 101-05

Science.gov (United States)

Weinstein, M. S.

1973-01-01

Based on the tests which were conducted, the fogging exhibited by the Kodak 101-05 glass plates when used in the Skylab S-183 experiment carrousels is a chemical fog caused by an outgassing within the carrousel. Testing has not yet been able to determine which chemical causes the fog or just what can be done to eliminate the problem.

Lifting index of the niosh lifting equation and low back pain

Directory of Open Access Journals (Sweden)

Eliana Remor Teixeira

2011-09-01

Full Text Available The purpose of this study is to assess the relationship of the Lifting Index obtained through the application of the NIOSH Lifting Equation and the incidence of low back pain among forty-eight workers involved in manual lifting tasks. It was applied the equation in eleven tasks and the workers were interviewed. The most unfavorable conditions presented themselves in the lifting destination. The variables that most contributed to the inadequate values of the Lifting Index were: the horizontal location, the lifting frequency and the vertical distance, beyond the high weight of the load. The incidence of low back pain in the last twelve months was 19%, whereas the incidence of work-related low back pain in the same period was 10%. In 72.7% of the tasks evaluated the Composite Lifting Index was more than three, which are considered as high ergonomic risk.

Art27 interacts with GATA4, FOG2 and NKX2.5 and is a novel co-repressor of cardiac genes.

Directory of Open Access Journals (Sweden)

Daniel R Carter

Full Text Available Transcription factors play a crucial role in regulation of cardiac biology. FOG-2 is indispensable in this setting, predominantly functioning through a physical interaction with GATA-4. This study aimed to identify novel co-regulators of FOG-2 to further elaborate on its inhibitory activity on GATA-4. The Art27 transcription factor was identified by a yeast-2-hybrid library screen to be a novel FOG-2 protein partner. Characterisation revealed that Art27 is co-expressed with FOG-2 and GATA-4 throughout cardiac myocyte differentiation and in multiple structures of the adult heart. Art27 physically interacts with GATA-4, FOG-2 and other cardiac transcription factors and by this means, down-regulates their activity on cardiac specific promoters α-myosin heavy chain, atrial natriuretic peptide and B-type natriuretic peptide. Regulation of endogenous cardiac genes by Art27 was shown using microarray analysis of P19CL6-Mlc2v-GFP cardiomyocytes. Together these results suggest that Art27 is a novel transcription factor that is involved in downregulation of cardiac specific genes by physically interacting and inhibiting the activity of crucial transcriptions factors involved in cardiac biology.

Measurement of moisture in smoldering smoke and implications for fog

Science.gov (United States)

Gary L. Achtemeier

2006-01-01

Smoke from wildland burning in association with fog has been implicated as a visibility hazard over roadways in the southern United States. A project began in 2002 to determine whether moisture released during the smoldering phases of southern prescribed burns could contribute to fog formation. Temperature and relative humidity measurements were taken from 27...

Analysis of fog effects on terrestrial Free Space optical communication links

KAUST Repository

Esmail, Maged Abdullah; Fathallah, Habib; Alouini, Mohamed-Slim

2016-01-01

the transmitted power will improve the system performance under light fog. However, under heavy fog, the effect is minor. To enhance the system performance under low visibility range, multi-hop link is used which can enhance the power budget by using short

Coastal fog during summer drought improves the water status of sapling trees more than adult trees in a California pine forest.

Science.gov (United States)

Baguskas, Sara A; Still, Christopher J; Fischer, Douglas T; D'Antonio, Carla M; King, Jennifer Y

2016-05-01

Fog water inputs can offset seasonal drought in the Mediterranean climate of coastal California and may be critical to the persistence of many endemic plant species. The ability to predict plant species response to potential changes in the fog regime hinges on understanding the ways that fog can impact plant physiological function across life stages. Our study uses a direct metric of water status, namely plant water potential, to understand differential responses of adult versus sapling trees to seasonal drought and fog water inputs. We place these measurements within a water balance framework that incorporates the varying climatic and soil property impacts on water budgets and deficit. We conducted our study at a coastal and an inland site within the largest stand of the regionally endemic bishop pine (Pinus muricata D. Don) on Santa Cruz Island. Our results show conclusively that summer drought negatively affects the water status of sapling more than adult trees and that sapling trees are also more responsive to changes in shallow soil moisture inputs from fog water deposition. Moreover, between the beginning and end of a large, late-season fog drip event, water status increased more for saplings than for adults. Relative to non-foggy conditions, we found that fog water reduces modeled peak water deficit by 80 and 70 % at the inland and coastal sites, respectively. Results from our study inform mechanistically based predictions of how population dynamics of this and other coastal species may be affected by a warmer, drier, and potentially less foggy future.

Relation between the size of fog droplets and their contact angles with CR39 surfaces

International Nuclear Information System (INIS)

Grosu, G; Andrzejewski, L; Veilleux, G; Ross, G G

2004-01-01

The formation of fog on CR39 surfaces has been studied. Water droplets form fog coalesce with time, especially during the first 20 s at the beginning of the formation of fog. Consequently, their mean diameter increases. Formation of fog being related to the wettability of the surfaces, the latter has been increased by the implantation of Ar ions into CR39 surfaces under an oxygen partial pressure. A very wetting CR39 surface with advancing (ACA) and receding (RCA) contact angles below 5 deg. has been obtained with an implantation dose of 1.28x10 17 Ar + cm -2 . In this condition, no formation of fog was observed. Characterization using x-ray photoelectron spectroscopy has shown that the molecular structure of CR39 is strongly modified by Ar + implantation, which would be responsible for the increase in wettability. Unfortunately, both ACA and RCA increase with time, which is called ageing, and the formation of fog is again observed. The diameter and concentration of water droplets forming fog have been plotted against the contact angle. These plots show that no formation of fog occurs for ACA 15 He + cm -2 and an energy of 2 keV, sufficient to push the ions deeper than the Ar depth profile, delays the ageing effect in such a way that ACA ≅ 40 deg. is reached after ∼2000 h and no formation of fog is observed during these first ∼2000 h

A Hybrid Scheme for Fine-Grained Search and Access Authorization in Fog Computing Environment

Science.gov (United States)

Xiao, Min; Zhou, Jing; Liu, Xuejiao; Jiang, Mingda

2017-01-01

In the fog computing environment, the encrypted sensitive data may be transferred to multiple fog nodes on the edge of a network for low latency; thus, fog nodes need to implement a search over encrypted data as a cloud server. Since the fog nodes tend to provide service for IoT applications often running on resource-constrained end devices, it is necessary to design lightweight solutions. At present, there is little research on this issue. In this paper, we propose a fine-grained owner-forced data search and access authorization scheme spanning user-fog-cloud for resource constrained end users. Compared to existing schemes only supporting either index encryption with search ability or data encryption with fine-grained access control ability, the proposed hybrid scheme supports both abilities simultaneously, and index ciphertext and data ciphertext are constructed based on a single ciphertext-policy attribute based encryption (CP-ABE) primitive and share the same key pair, thus the data access efficiency is significantly improved and the cost of key management is greatly reduced. Moreover, in the proposed scheme, the resource constrained end devices are allowed to rapidly assemble ciphertexts online and securely outsource most of decryption task to fog nodes, and mediated encryption mechanism is also adopted to achieve instantaneous user revocation instead of re-encrypting ciphertexts with many copies in many fog nodes. The security and the performance analysis show that our scheme is suitable for a fog computing environment. PMID:28629131

A Hybrid Scheme for Fine-Grained Search and Access Authorization in Fog Computing Environment.

Science.gov (United States)

Xiao, Min; Zhou, Jing; Liu, Xuejiao; Jiang, Mingda

2017-06-17

In the fog computing environment, the encrypted sensitive data may be transferred to multiple fog nodes on the edge of a network for low latency; thus, fog nodes need to implement a search over encrypted data as a cloud server. Since the fog nodes tend to provide service for IoT applications often running on resource-constrained end devices, it is necessary to design lightweight solutions. At present, there is little research on this issue. In this paper, we propose a fine-grained owner-forced data search and access authorization scheme spanning user-fog-cloud for resource constrained end users. Compared to existing schemes only supporting either index encryption with search ability or data encryption with fine-grained access control ability, the proposed hybrid scheme supports both abilities simultaneously, and index ciphertext and data ciphertext are constructed based on a single ciphertext-policy attribute based encryption (CP-ABE) primitive and share the same key pair, thus the data access efficiency is significantly improved and the cost of key management is greatly reduced. Moreover, in the proposed scheme, the resource constrained end devices are allowed to rapidly assemble ciphertexts online and securely outsource most of decryption task to fog nodes, and mediated encryption mechanism is also adopted to achieve instantaneous user revocation instead of re-encrypting ciphertexts with many copies in many fog nodes. The security and the performance analysis show that our scheme is suitable for a fog computing environment.

Fog prediction using the modified asymptotic liquid water content vertical distribution formulation with the Weather Research and Forecasting model

Science.gov (United States)

Kim, E.; Lee, S.; Kim, J.; Chae, D.

2017-12-01

Fog forecasts have difficulty in forecasting due to temporal and spatial resolution problems, high numerical computations, complicated mechanisms related to turbulence in order to analyze the fog in the model, and a lack of appropriate fog physical processes. Conventional fog prediction is based on the surface visibility threshold "fog diagnosis method is based on the fog related variables near the surface, such as visibility, low stratus, relative humidity and wind speed but this method only predicts fog occurrence not fog intensity. To improve this, a new fog diagnostic scheme, based on an asymptotic analytical study of radiation fog (Zhou and Ferrier 2008, ZF08) is to increase the accuracy of fog prediction by calculating the vertical LWC considering cooling, turbulence and droplet settling, visibility, surface relative humidity and low stratus. In this study, we intend to improve fog prediction through the Weather Research and Forecasting (WRF) model using high-resolution data. Although the prediction accuracy can be improved by combining the WRF Planetary Boundary Layer (PBL) scheme and 1 dimension (1D) model, it is necessary to increase the vertical resolution in the boundary layer to implement the fog formation and persistence mechanism in the internal boundary layer in the PBL more accurately, we'll modify the algorithm to enhance the effects of turbulence and then compare the newly predicted fog and observations to determine the accuracy of the forecast of the fog occurring on the Korean peninsula.

A Study of Fog Characteristics using Free-Space Optical Wireless Links

Directory of Open Access Journals (Sweden)

M. S. Awan

2010-06-01

Full Text Available A technique for modeling the fog droplet size distributions using modified gamma distribution has been demonstrated by considering two separate radiation fog events recorded in Graz (Austria and Prague (Czech Republic. The measurement of liquid water content (LWC and the optical attenuations at visible wavelength are used to form equations to obtain the three parameters of the modified gamma distribution i.e., the slope (Λ, the intercept (N0 and the shape parameter (m. Calculated attenuation or LWC from the retrieved parameters are in excellent agreement with attenuation or LWC obtained from the measurement. Hence this method is useful in the study of fog microphysics and in modeling the fog attenuations for terrestrial FSO links in situations when our measurement data contains values of attenuations only, or liquid water content only or both at a particular location. For the two case studies, Graz and Prague, we obtained the DSD parameters Λ=3.547 ± 1.935, N0 =3.834 ± 2.239, m=6.135 ± 2.692 and Λ=5.882 ± 2.889, N0 =13.41 ± 3.875, m=5.288 ± 3.113, respectively. It is evident that the observed behavior of computed modified gamma distribution parameters for Graz and Prague is closely the same and is consistent with the previous literature for the radiation (continental fog. Moreover, we observed the variation of the computed DSD parameters at the different stages of fog (formation, maturity and dissipation phases indicating different microphysical processes at each stage.

PLAM - a meteorological pollution index for air quality and its applications in fog-haze forecasts in North China

Science.gov (United States)

Yang, Y. Q.; Wang, J. Z.; Gong, S. L.; Zhang, X. Y.; Wang, H.; Wang, Y. Q.; Wang, J.; Li, D.; Guo, J. P.

2016-02-01

Using surface meteorological observation and high-resolution emission data, this paper discusses the application of the PLAM/h index (Parameter Linking Air-quality to Meteorological conditions/haze) in the prediction of large-scale low visibility and fog-haze events. Based on the two-dimensional probability density function diagnosis model for emissions, the study extends the diagnosis and prediction of the meteorological pollution index PLAM to the regional visibility fog-haze intensity. The results show that combining the influence of regular meteorological conditions and emission factors together in the PLAM/h parameterization scheme is very effective in improving the diagnostic identification ability of the fog-haze weather in North China. The determination coefficients for four seasons (spring, summer, autumn, and winter) between PLAM/h and visibility observation are 0.76, 0.80, 0.96, and 0.86, respectively, and all of their significance levels exceed 0.001, showing the ability of PLAM/h to predict the seasonal changes and differences of fog-haze weather in the North China region. The high-value correlation zones are located in Jing-Jin-Ji (Beijing, Tianjin, Hebei), Bohai Bay rim, and southern Hebei-northern Henan, indicating that the PLAM/h index is related to the distribution of frequent heavy fog-haze weather in North China and the distribution of emission high-value zone. Through comparative analysis of the heavy fog-haze events and large-scale clear-weather processes in winter and summer, it is found that PLAM/h index 24 h forecast is highly correlated with the visibility observation. Therefore, the PLAM/h index has good capability in identification, analysis, and forecasting.

Calculation and measurement of fog droplet size

International Nuclear Information System (INIS)

Laali, A.R.; Courant, J.J.; Kleitz, A.

1991-01-01

This paper outlines the elements involved in calculation and measurement of fog droplet size in steam turbines. The condensation calculations are performed for a 600 MW LP fossil fired, and for a 900 MW LP nuclear turbine. A simplified method based on classical condensation theory is used for these calculations. The fog droplet size measurement are carried out downstream of the last moving blades of these turbines in order to validate the program. The comparison between the results could lead to a better understanding of the condensation process in steam turbines. Some large droplet (re-entrained droplet) measurements are also taken using a microvideo probe

Evaluation of fog predictions and detection, Phase 2 : draft final report.

Science.gov (United States)

2016-09-01

On January 29, 2012 at about 4:00 am a thick fog and smoke caused a multiple car crash just south of Gainesville, Florida. 11 people were killed and 18 were hospitalized. Nationally there are about 38,000 fog related accidents which result in about 6...

A Wavelet-based method for processing signal of fog in strap-down inertial systems

Energy Technology Data Exchange (ETDEWEB)

Han, D.; Xiong, C.; Liu, H. [Huazhong University of Science & Technology, Wuhan (China)

2009-07-01

Fibre optical gyroscopes (FOGs) have been applied widely in many fields in contrast, with their counterparts such as mechanical gyroscopes and ring laser gyroscopes. The precision of FOG is affected significantly by bias drift, angle random walk temperature effects and noises. Especially, uncertain disturbances resulting from road irregularities often affect accuracy of strap-down inertial system (SINS). Hence, eliminating, uncertain disturbances from outputs of it FOG plays a crucial role to improve accuracy of SINS. This paper presents a wavelet-based method for denoising signals of FOGs in SINS used for exploring and rescuing robots in coal mines. Property of road irregularities in mines is taken into account as a key factor resulting in uncertain disturbances in this research. Both frequency band and amplitude of uncertain disturbances are introduced to choose filtering thresholds. Experimental results have demonstrated that the proposed method can efficiently eliminate uncertain disturbances due to road irregularities from outputs of FOGs and improve accuracy of surrogate data. It indicates that the proposed method has a significant potential in FOG-related applications.

Phosphorylation state of a Tob/BTG protein, FOG-3, regulates initiation and maintenance of the Caenorhabditis elegans sperm fate program.

Science.gov (United States)

Lee, Myon-Hee; Kim, Kyung Won; Morgan, Clinton T; Morgan, Dyan E; Kimble, Judith

2011-05-31

FOG-3, the single Caenorhabditis elegans Tob/BTG protein, directs germ cells to adopt the sperm fate at the expense of oogenesis. Importantly, FOG-3 activity must be maintained for the continued production of sperm that is typical of the male sex. Vertebrate Tob proteins have antiproliferative activity and ERK phosphorylation of Tob proteins has been proposed to abrogate "antiproliferative" activity. Here we investigate FOG-3 phosphorylation and its effect on sperm fate specification. We found both phosphorylated and unphosphorylated forms of FOG-3 in nematodes. We then interrogated the role of FOG-3 phosphorylation in sperm fate specification. Specifically, we assayed FOG-3 transgenes for rescue of a fog-3 null mutant. Wild-type FOG-3 rescued both initiation and maintenance of sperm fate specification. A FOG-3 mutant with its four consensus ERK phosphorylation sites substituted to alanines, called FOG-3(4A), rescued partially: sperm were made transiently but not continuously in both sexes. A different FOG-3 mutant with its sites substituted to glutamates, called FOG-3(4E), had no rescuing activity on its own, but together with FOG-3(4A) rescue was complete. Thus, when FOG-3(4A) and FOG-3(4E) were both introduced into the same animals, sperm fate specification was not only initiated but also maintained, resulting in continuous spermatogenesis in males. Our findings suggest that unphosphorylated FOG-3 initiates the sperm fate program and that phosphorylated FOG-3 maintains that program for continued sperm production typical of males. We discuss implications of our results for Tob/BTG proteins in vertebrates.

On the logarithmic-singularity correction in the kernel function method of subsonic lifting-surface theory

Science.gov (United States)

Lan, C. E.; Lamar, J. E.

1977-01-01

A logarithmic-singularity correction factor is derived for use in kernel function methods associated with Multhopp's subsonic lifting-surface theory. Because of the form of the factor, a relation was formulated between the numbers of chordwise and spanwise control points needed for good accuracy. This formulation is developed and discussed. Numerical results are given to show the improvement of the computation with the new correction factor.

The Research on the Spectral Characteristics of Sea Fog Based on Caliop and Modis Data

Science.gov (United States)

Wan, J.; Su, J.; Liu, S.; Sheng, H.

2018-04-01

In view of that difficulty of distinguish between sea fog and low cloud by optical remote sensing mean, the research on spectral characteristics of sea fog is focused and carried out. The satellite laser radar CALIOP data and the high spectral MODIS data were obtained from May to December 2017, and the scattering coefficient and the vertical height information were extracted from the atmospheric attenuation of the lower star to extract the sea fog sample points, and the spectral response curve based on MODIS was formed to analyse the spectral response characteristics of the sea fog, thus providing a theoretical basis for the monitoring of sea fog with optical remote sensing image.

THE RESEARCH ON THE SPECTRAL CHARACTERISTICS OF SEA FOG BASED ON CALIOP AND MODIS DATA

Directory of Open Access Journals (Sweden)

J. Wan

2018-04-01

Full Text Available In view of that difficulty of distinguish between sea fog and low cloud by optical remote sensing mean, the research on spectral characteristics of sea fog is focused and carried out。The satellite laser radar CALIOP data and the high spectral MODIS data were obtained from May to December 2017, and the scattering coefficient and the vertical height information were extracted from the atmospheric attenuation of the lower star to extract the sea fog sample points, and the spectral response curve based on MODIS was formed to analyse the spectral response characteristics of the sea fog, thus providing a theoretical basis for the monitoring of sea fog with optical remote sensing image.

A security mechanism based on evolutionary game in fog computing

Directory of Open Access Journals (Sweden)

Yan Sun

2018-02-01

Full Text Available Fog computing is a distributed computing paradigm at the edge of the network and requires cooperation of users and sharing of resources. When users in fog computing open their resources, their devices are easily intercepted and attacked because they are accessed through wireless network and present an extensive geographical distribution. In this study, a credible third party was introduced to supervise the behavior of users and protect the security of user cooperation. A fog computing security mechanism based on human nervous system is proposed, and the strategy for a stable system evolution is calculated. The MATLAB simulation results show that the proposed mechanism can reduce the number of attack behaviors effectively and stimulate users to cooperate in application tasks positively.

A security mechanism based on evolutionary game in fog computing.

Science.gov (United States)

Sun, Yan; Lin, Fuhong; Zhang, Nan

2018-02-01

Fog computing is a distributed computing paradigm at the edge of the network and requires cooperation of users and sharing of resources. When users in fog computing open their resources, their devices are easily intercepted and attacked because they are accessed through wireless network and present an extensive geographical distribution. In this study, a credible third party was introduced to supervise the behavior of users and protect the security of user cooperation. A fog computing security mechanism based on human nervous system is proposed, and the strategy for a stable system evolution is calculated. The MATLAB simulation results show that the proposed mechanism can reduce the number of attack behaviors effectively and stimulate users to cooperate in application tasks positively.

Lift truck safety review

Energy Technology Data Exchange (ETDEWEB)

Cadwallader, L.C.

1997-03-01

This report presents safety information about powered industrial trucks. The basic lift truck, the counterbalanced sit down rider truck, is the primary focus of the report. Lift truck engineering is briefly described, then a hazard analysis is performed on the lift truck. Case histories and accident statistics are also given. Rules and regulations about lift trucks, such as the US Occupational Safety an Health Administration laws and the Underwriter`s Laboratories standards, are discussed. Safety issues with lift trucks are reviewed, and lift truck safety and reliability are discussed. Some quantitative reliability values are given.

Lift truck safety review

International Nuclear Information System (INIS)

Cadwallader, L.C.

1997-03-01

This report presents safety information about powered industrial trucks. The basic lift truck, the counterbalanced sit down rider truck, is the primary focus of the report. Lift truck engineering is briefly described, then a hazard analysis is performed on the lift truck. Case histories and accident statistics are also given. Rules and regulations about lift trucks, such as the US Occupational Safety an Health Administration laws and the Underwriter's Laboratories standards, are discussed. Safety issues with lift trucks are reviewed, and lift truck safety and reliability are discussed. Some quantitative reliability values are given

Combining Fog Computing with Sensor Mote Machine Learning for Industrial IoT.

Science.gov (United States)

Lavassani, Mehrzad; Forsström, Stefan; Jennehag, Ulf; Zhang, Tingting

2018-05-12

Digitalization is a global trend becoming ever more important to our connected and sustainable society. This trend also affects industry where the Industrial Internet of Things is an important part, and there is a need to conserve spectrum as well as energy when communicating data to a fog or cloud back-end system. In this paper we investigate the benefits of fog computing by proposing a novel distributed learning model on the sensor device and simulating the data stream in the fog, instead of transmitting all raw sensor values to the cloud back-end. To save energy and to communicate as few packets as possible, the updated parameters of the learned model at the sensor device are communicated in longer time intervals to a fog computing system. The proposed framework is implemented and tested in a real world testbed in order to make quantitative measurements and evaluate the system. Our results show that the proposed model can achieve a 98% decrease in the number of packets sent over the wireless link, and the fog node can still simulate the data stream with an acceptable accuracy of 97%. We also observe an end-to-end delay of 180 ms in our proposed three-layer framework. Hence, the framework shows that a combination of fog and cloud computing with a distributed data modeling at the sensor device for wireless sensor networks can be beneficial for Industrial Internet of Things applications.

CHEMIFOGV - A Model to Simulate Radiation Fogs and their Interaction with Vegetation and Chemistry

International Nuclear Information System (INIS)

Winterrath, Tanja; Bott, Andreas

2001-01-01

Radiation fog is an important modifier of atmospheric compounds in the planetary boundary layer. In vegetated areas effects are especially pronounced due to the enlarged surface area. Besides affecting the lower boundary of atmospheric models fog acts as a multi-phase reaction chamber leading to acid deposition. Here we present the 1-dimensional radiation fog modelCHEMIFOG V to simulate regional radiation fog events. The key feature of the fog model is the detailed microphysics, where the aerosol/droplet spectrum is described with a joint 2-dimensional distribution, but also the dynamics, thermodynamics, and radiative transfer are calculated. To investigate the interaction between fog and the biosphere a multi-layer vegetation module, including a soil module as well as a dry deposition module were coupled. Vegetation influences the dynamics, thermodynamics, and the radiation field of the lowest atmospheric layers. With CHEMIFOG V , numerical case studies on dry and moist deposition processes on vegetation surfaces were performed. Hereby multi-phase chemistry and the processing of aerosols were considered. The results show that the chemical composition of the deposited fog droplets is mainly determined by the aerosol composition. Dry deposition fluxes are dependent on the incoming radiation and the leaves' surface conditions with respect to water coverage.Due to chemical aerosol processing and deposition, the aerosol spectrum is significantly modified in the planetary boundary layer

Multiphase chemistry in a microphysical radiation fog model—A numerical study

Science.gov (United States)

Bott, Andreas; Carmichael, Gregory R.

A microphysical radiation fog model is coupled with a detailed chemistry module to simulate chemical reactions in the gas phase and in fog water during a radiation fog event. In the chemical part of the model the microphysical particle spectrum is subdivided into three size classes corresponding to non-activated aerosol particles, small and large fog droplets. Chemical reactions in the liquid phase are separately calculated in the small and in the large droplet size class. The impact of the chemical constitution of activated aerosols on fogwater chemistry is considered in the model simulations. The mass transfer of chemical species between the gas phase and the two liquid phases is treated in detail by solving the corresponding coupled differential equation system. The model also accounts for concentration changes of gas-phase and aqueous-phase chemical species which are induced by turbulence, gravitational settling and by evaporation/condensation processes. Numerical results demonstrate that fogwater chemistry is strongly controlled by dynamic processes, i.e. the vertical growth of the fog, turbulent mixing processes and the gravitational settling of the particles. The concentrations of aqueous-phase chemical species are different in the two droplet size classes. Reactands with lower water solubility are mainly found in the large droplet size class because the characteristic time for their mass transfer from the gas phase into the liquid phase is essentially longer than the characteristic time for the formation of large fog droplets. Species with high water solubility are rapidly transferred into the small fog droplets and are then washed out by wet deposition before these particles grow further to form large droplets. Thus, the concentrations of the major ions (NO 3-, NH 4+) are much higher in small than in large droplets, yielding distinctly lower pH values of the small particles. In the present study the reaction of sulfur with H 2O 2 and the Fe

Fog and dew climatology over Hisar, India

International Nuclear Information System (INIS)

Surender, S.; Diwan, S.; Rao, V.U.M.

2006-05-01

In many arid and semi-arid areas, pumped ground water and the water from streams, rivers and reservoirs is no longer sufficient to cover the ever increasing water demand. Therefore new interest in 'marginal' water resources like fog and dew harvesting are to be developed after studying climatology of these parameters in a region. The observations on dew and fog events recorded at Hisar, representing semi-arid region of India during winter season (October to March) for the period 1980 to 2005 have been analyzed. The total annual dew amount in winter season ranged between 33 mm (1987-88) and 79 mm (1981-82) during the period under study. The seasonal dewfall showed a decreasing trend of 1.4 mm during the period under investigation. Average maximum dew events (26.1) were recorded during November and average minimum dew events were recorded in February. In a particular season, the highest dew events (168) were observed during the winter seasons of 1982-83 and 1983-84, whereas, the minimum number of dew events (97) was reported during 1998-99. Interestingly, an increasing trend (1.3 day/season) in occurrence of fog events was seen. Average maximum foggy events (8.7) recorded in a month were observed in January. In a particular season, the maximum foggy events (41) were recorded during 2002-03 and the minimum (2) during 1983-84. To achieve the objective of alternate source of water and to assess the impact of dew and fog on agricultural crops for their growth and development, inputs from various specialized disciplines and allied sciences engaged in meteorological applications along with forecasting skills from non scientific quarters are needed to predict the weather parameter accurately, thus the active cooperation between meteorological/remote sensing agencies, agricultural organizations and farming community is needed for sustainable agricultural development in scarce/limited water availability regions. (author)

Observation of sandhill cranes' (Grus canadensis) flight behavior in heavy fog

Science.gov (United States)

Kirsch, Eileen M.; Wellik, Mike J.; Suarez, Manuel J.; Diehl, Robert H.; Lutes, Jim; Woyczik, Wendy; Krapfl, Jon; Sojda, Richard S.

2015-01-01

The behaviors of birds flying in low visibility conditions remain poorly understood. We had the opportunity to monitor Sandhill Cranes (Grus canadensis) flying in heavy fog with very low visibility during a comprehensive landscape use study of refuging cranes in the Horicon Marsh in southeastern Wisconsin. As part of the study, we recorded flight patterns of cranes with a portable marine radar at various locations and times of day, and visually counted cranes as they departed the roost in the morning. We compared flight patterns during a fog event with those recorded during clear conditions. In good visibility, cranes usually departed the night roost shortly after sunrise and flew in relatively straight paths toward foraging areas. In fog, cranes departed the roost later in the day, did not venture far from the roost, engaged in significantly more circling flight, and returned to the roost site rather than proceeding to foraging areas. We also noted that compared to mornings with good visibility, cranes flying in fog called more frequently than usual. The only time in this 2-year study that observers heard young of the year calling was during the fog event. The observed behavior of cranes circling and lingering in an area while flying in poor visibility conditions suggests that such situations may increase chances of colliding with natural or anthropogenic obstacles in the vicinity.

Two-dimensional unsteady lift problems in supersonic flight

Science.gov (United States)

Heaslet, Max A; Lomax, Harvard

1949-01-01

The variation of pressure distribution is calculated for a two-dimensional supersonic airfoil either experiencing a sudden angle-of-attack change or entering a sharp-edge gust. From these pressure distributions the indicial lift functions applicable to unsteady lift problems are determined for two cases. Results are presented which permit the determination of maximum increment in lift coefficient attained by an unrestrained airfoil during its flight through a gust. As an application of these results, the minimum altitude for safe flight through a specific gust is calculated for a particular supersonic wing of given strength and wing loading.

Brain "fog," inflammation and obesity : key aspects of neuropsychiatric disorders improved by luteolin

Directory of Open Access Journals (Sweden)

Theoharis Constantin Theoharides

2015-07-01

Full Text Available Brain fog is a constellation of symptoms that include reduced cognition, inability to concentrate and multitask, as well as loss of short and long term memory. Brain fog characterizes patients with autism spectrum disorders (ASDs, celiac disease, chronic fatigue syndrome, fibromyalgia, mastocytosis and postural tachycardia syndrome (POTS, as well as minimal cognitive impairment, an early clinical presentation of Alzheimer’s disease (AD, and other neuropsychiatric disorders. Brain fog may be due to inflammatory molecules, including adipocytokines and histamine released from mast cells (MCs further stimulating microglia activation, and causing focal brain inflammation. Recent reviews have described the potential use of natural flavonoids for the treatment of neuropsychiatric and neurodegenerative diseases. The flavone luteolin has numerous useful actions that include: anti-oxidant, anti-inflammatory, microglia inhibition, neuroprotection, and memory increase. A liposomal luteolin formulation in olive fruit extract improved attention in children with ASDs and brain fog in mastocytosis patients. Methylated luteolin analogues with increased activity and better bioavailability could be developed into effective treatments for neuropsychiatric disorders and brain fog.

Brain "fog," inflammation and obesity: key aspects of neuropsychiatric disorders improved by luteolin.

Science.gov (United States)

Theoharides, Theoharis C; Stewart, Julia M; Hatziagelaki, Erifili; Kolaitis, Gerasimos

2015-01-01

Brain "fog" is a constellation of symptoms that include reduced cognition, inability to concentrate and multitask, as well as loss of short and long term memory. Brain "fog" characterizes patients with autism spectrum disorders (ASDs), celiac disease, chronic fatigue syndrome, fibromyalgia, mastocytosis, and postural tachycardia syndrome (POTS), as well as "minimal cognitive impairment," an early clinical presentation of Alzheimer's disease (AD), and other neuropsychiatric disorders. Brain "fog" may be due to inflammatory molecules, including adipocytokines and histamine released from mast cells (MCs) further stimulating microglia activation, and causing focal brain inflammation. Recent reviews have described the potential use of natural flavonoids for the treatment of neuropsychiatric and neurodegenerative diseases. The flavone luteolin has numerous useful actions that include: anti-oxidant, anti-inflammatory, microglia inhibition, neuroprotection, and memory increase. A liposomal luteolin formulation in olive fruit extract improved attention in children with ASDs and brain "fog" in mastocytosis patients. Methylated luteolin analogs with increased activity and better bioavailability could be developed into effective treatments for neuropsychiatric disorders and brain "fog."

Regulation of Epithelial Morphogenesis by the G-Protein Coupled Receptor Mist and its Ligand Fog*

Science.gov (United States)

Manning, Alyssa J.; Peters, Kimberly A.; Peifer, Mark; Rogers, Stephen L.

2014-01-01

Epithelial morphogenesis is essential for shaping organs and tissues and for establishment of the three embryonic germ layers during gastrulation. Studies of gastrulation in Drosophila have provided insight into how epithelial morphogenesis is governed by developmental patterning mechanisms. We developed an assay to recapitulate morphogenetic shape changes in individual cultured cells, and used RNAi-based screening to identify Mist, a Drosophila G protein-coupled receptor (GPCR) that transduces signals from the secreted ligand Folded gastrulation (Fog) in cultured cells. Mist functioned in Fog-dependent embryonic morphogenesis, and the transcription factor Snail regulated expression of mist in zygotes. Our data revealed how a cell fate transcriptional program acts through a ligand-GPCR pair to stimulate epithelial morphogenetic shape changes. PMID:24222713

Functional traits variation explains the distribution of Aextoxicon punctatum (Aextoxicaceae in pronounced moisture gradients within fog-dependent forest fragments

Directory of Open Access Journals (Sweden)

Beatriz eSalgado-Negret

2015-07-01

Full Text Available Climate change and fragmentation are major threats to world forests. Understanding how functional traits related to drought tolerance change across small-scale, pronounced moisture gradients in fragmented forests is important to predict species’ responses to these threats. In the case of Aextoxicon punctatum, a dominant canopy tree in fog-dependent rain forest patches in semiarid Chile, we explored how the magnitude, variability and correlation patterns of leaf and xylem vessel traits and hydraulic conductivity varied across soil moisture gradients established within and among forest patches of different size, which are associated with differences in tree establishment and mortality patterns. Leaf traits varied across soil-moisture gradients produced by fog interception. Trees growing at drier leeward edges showed higher LMA (leaf mass per area, trichome and stomatal density than trees from the wetter core and windward zones. In contrast, xylem vessel traits (vessels diameter and density did not vary producing loss of hydraulic conductivity at drier leeward edges. We also detected higher levels of phenotypic integration and variability at leeward edges. The ability of A. punctatum to modify leaf traits in response to differences in soil moisture availability established over short distances (<500 m facilitates its persistence in contrasting microhabitats within forest patches. However, xylem anatomy showed limited plasticity, which increases cavitation risk at leeward edges. Greater patch fragmentation, together with fluctuations in irradiance and soil moisture in small patches, could result in higher risk of drought-related tree mortality, with profound impacts on hydrological balances at the ecosystem scale.

Exploring Fog Water Harvesting Potential and Quality in the Asir Region, Kingdom of Saudi Arabia

Science.gov (United States)

Gandhidasan, P.; Abualhamayel, H. I.

2012-05-01

During the last decade, the exploitation of the existing water resources in the Asir region of the Kingdom of Saudi Arabia has considerably increased due to both the decrease in annual precipitation and the added population pressures from the growing tourist industry. To face the conventional water shortage, attention has been mainly focused on desalination of water. To save the region from severe water shortage, additional new water sources that are low-cost and renewable must be identified. There exists an alternative source of water such as fog water harvesting. Fog forms in the Asir Region more frequently between December and February compared to the other months of the year. This paper presents the study of the climatic conditions in the Asir region of the Kingdom to identify the most suitable location for fog water collection as well as design and testing of two large fog collectors (LFCs) of size 40 m2 along with standard fog collectors (SFCs) of 1 m2 in that region. During the period from 27 December 2009 to 9 March 2010, a total of 3,128.4 and 2,562.4 L of fog water were collected by the LFC at two sites in the Al-Sooda area of the Asir region, near Abha. Experimental results indicate that fog water collection can be combined with rain water harvesting systems to increase water yield during the rainy season. The quality of the collected fog water was analyzed and compared to the World Health Organization (WHO) drinking water standards and found to be potable. An economic analysis was carried out for the proposed method of obtaining fresh water from the fog. The study suggests a clear tendency that in terms of both quality and magnitude of yield, fog is a viable source of water and can be successfully used to supplement water supplies in the Asir region of the Kingdom.

FOG: Fighting the Achilles' Heel of Gossip Protocols with Fountain Codes

Science.gov (United States)

Champel, Mary-Luc; Kermarrec, Anne-Marie; Le Scouarnec, Nicolas

Gossip protocols are well known to provide reliable and robust dissemination protocols in highly dynamic systems. Yet, they suffer from high redundancy in the last phase of the dissemination. In this paper, we combine fountain codes (rateless erasure-correcting codes) together with gossip protocols for a robust and fast content dissemination in large-scale dynamic systems. The use of fountain enables to eliminate the unnecessary redundancy of gossip protocols. We propose the design of FOG, which fully exploits the first exponential growth phase (where the data is disseminated exponentially fast) of gossip protocols while avoiding the need for the shrinking phase by using fountain codes. FOG voluntarily increases the number of disseminations but limits those disseminations to the exponential growth phase. In addition, FOG creates a split-graph overlay that splits the peers between encoders and forwarders. Forwarder peers become encoders as soon as they have received the whole content. In order to benefit even further and quicker from encoders, FOG biases the dissemination towards the most advanced peers to make them complete earlier.

Airfoil design: Finding the balance between design lift and structural stiffness

DEFF Research Database (Denmark)

Bak, Christian; Gaudern, Nicholas; Zahle, Frederik

2014-01-01

When upscaling wind turbine blades there is an increasing need for high levels of structural efficiency. In this paper the relationships between the aerodynamic characteristics; design lift and lift-drag ratio; and the structural characteristics were investigated. Using a unified optimization setup......, the design lift coefficient increases if the box length reduces and at the same time the relative thickness increases. Even though the conclusions are specific to the airfoil design approach used, the study indicated that an increased design lift required slightly higher relative thickness compared...... to airfoils with lower design lift to maintain the flapwise stiffness. Also, the study indicated that the lift-drag ratio as a function of flapwise stiffness was relatively independent of the airfoil design with a tendency that the lift-drag ratio decreased for large box lengths. The above conclusions were...

Deposition of particle-bound radionuclides in dry weather, fog, rain and snowfall

International Nuclear Information System (INIS)

Oberschachtsiek, D.; Sparmacher, H.; Kreh, R.; Adam, M.; Fuelber, K.; Stegger, J.; Bonka, H.

1992-01-01

Radionuclides emitted from nuclear plants and installations are transported in dry weather, because of turbulences and sedimentations, to plant parts above ground and near the ground and to other areas, and deposited there. The deposited activity is proportional to the activity concentration near the deposition area. In the case of particle-bound radionuclides it depends on the aerodynamic particle diameter, surface quality and other factors. In a large number of experiments deposition velocity was measured. In fog the particles to which radionuclides are bound grow by coagulation and condensation. The aerosol size spectrum changes with increasing distance from the place of emission. The type of the fog and the form of the emitted spectrum are important factors which influence this process. With normal activity distributions as a function of the aerodynamic particle diameter, the deposition velocity increases with the distance from the place of emission, up to a final value, due to the shift of the spectrum to larger diameters. (orig.) [de

Fog collecting biomimetic surfaces: Influence of microstructure and wettability.

Science.gov (United States)

Azad, M A K; Ellerbrok, D; Barthlott, W; Koch, K

2015-01-19

We analyzed the fog collection efficiency of three different sets of samples: replica (with and without microstructures), copper wire (smooth and microgrooved) and polyolefin mesh (hydrophilic, superhydrophilic and hydrophobic). The collection efficiency of the samples was compared in each set separately to investigate the influence of microstructures and/or the wettability of the surfaces on fog collection. Based on the controlled experimental conditions chosen here large differences in the efficiency were found. We found that microstructured plant replica samples collected 2-3 times higher amounts of water than that of unstructured (smooth) samples. Copper wire samples showed similar results. Moreover, microgrooved wires had a faster dripping of water droplets than that of smooth wires. The superhydrophilic mesh tested here was proved more efficient than any other mesh samples with different wettability. The amount of collected fog by superhydrophilic mesh was about 5 times higher than that of hydrophilic (untreated) mesh and was about 2 times higher than that of hydrophobic mesh.

Natural Contamination and Surface Flashover on Silicone Rubber Surface under Haze–Fog Environment

Directory of Open Access Journals (Sweden)

Ang Ren

2017-10-01

Full Text Available Anti-pollution flashover of insulator is important for power systems. In recent years, haze-fog weather occurs frequently, which makes discharge occurs easily on the insulator surface and accelerates insulation aging of insulator. In order to study the influence of haze-fog on the surface discharge of room temperature vulcanized silicone rubber, an artificial haze-fog lab was established. Based on four consecutive years of insulator contamination accumulation and atmospheric sampling in haze-fog environment, the contamination configuration appropriate for RTV-coated surface discharge test under simulation environment of haze-fog was put forward. ANSYS Maxwell was used to analyze the influence of room temperature vulcanized silicone rubber surface attachments on electric field distribution. The changes of droplet on the polluted room temperature vulcanized silicone rubber surface and the corresponding surface flashover voltage under alternating current (AC, direct current (DC positive polar (+, and DC negative polar (− power source were recorded by a high speed camera. The results are as follows: The main ion components from haze-fog atmospheric particles are NO3−, SO42−, NH4+, and Ca2+. In haze-fog environment, both the equivalent salt deposit density (ESDD and non-soluble deposit density (NSDD of insulators are higher than that under general environment. The amount of large particles on the AC transmission line is greater than that of the DC transmission line. The influence of DC polarity power source on the distribution of contamination particle size is not significant. After the deposition of haze-fog, the local conductivity of the room temperature vulcanized silicone rubber surface increased, which caused the flashover voltage reduce. Discharge is liable to occur at the triple junction point of droplet, air, and room temperature vulcanized silicone rubber surface. After the deformation or movement of droplets, a new triple junction

Robot Vision to Monitor Structures in Invisible Fog Environments Using Active Imaging Technology

Energy Technology Data Exchange (ETDEWEB)

Park, Seungkyu; Park, Nakkyu; Baik, Sunghoon; Choi, Youngsoo; Jeong, Kyungmin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

Active vision is a direct visualization technique using a highly sensitive image sensor and a high intensity illuminant. Range-gated imaging (RGI) technique providing 2D and 3D images is one of emerging active vision technologies. The RGI technique extracts vision information by summing time sliced vision images. In the RGI system, objects are illuminated for ultra-short time by a high intensity illuminant and then the light reflected from objects is captured by a highly sensitive image sensor with the exposure of ultra-short time. The RGI system provides 2D and 3D image data from several images and it moreover provides clear images from invisible fog and smoke environment by using summing of time-sliced images. Nowadays, the Range-gated (RG) imaging is an emerging technology in the field of surveillance for security applications, especially in the visualization of invisible night and fog environment. Although RGI viewing was discovered in the 1960's, this technology is, nowadays, more and more applicable by virtue of the rapid development of optical and sensor technologies, such as highly sensitive imaging sensor and ultra-short pulse laser light. In contrast to passive vision systems, this technology enables operation even in harsh environments like fog and smoke. During the past decades, several applications of this technology have been applied in target recognition and in harsh environments, such as fog, underwater vision. Also, this technology has been demonstrated 3D imaging based on range-gated imaging. In this paper, a robot system to monitor structures in invisible fog environment is developed using an active range-gated imaging technique. The system consists of an ultra-short pulse laser device and a highly sensitive imaging sensor. The developed vision system is carried out to monitor objects in invisible fog environment. The experimental result of this newly approach vision system is described in this paper. To see invisible objects in fog

Robot Vision to Monitor Structures in Invisible Fog Environments Using Active Imaging Technology

International Nuclear Information System (INIS)

Park, Seungkyu; Park, Nakkyu; Baik, Sunghoon; Choi, Youngsoo; Jeong, Kyungmin

2014-01-01

Active vision is a direct visualization technique using a highly sensitive image sensor and a high intensity illuminant. Range-gated imaging (RGI) technique providing 2D and 3D images is one of emerging active vision technologies. The RGI technique extracts vision information by summing time sliced vision images. In the RGI system, objects are illuminated for ultra-short time by a high intensity illuminant and then the light reflected from objects is captured by a highly sensitive image sensor with the exposure of ultra-short time. The RGI system provides 2D and 3D image data from several images and it moreover provides clear images from invisible fog and smoke environment by using summing of time-sliced images. Nowadays, the Range-gated (RG) imaging is an emerging technology in the field of surveillance for security applications, especially in the visualization of invisible night and fog environment. Although RGI viewing was discovered in the 1960's, this technology is, nowadays, more and more applicable by virtue of the rapid development of optical and sensor technologies, such as highly sensitive imaging sensor and ultra-short pulse laser light. In contrast to passive vision systems, this technology enables operation even in harsh environments like fog and smoke. During the past decades, several applications of this technology have been applied in target recognition and in harsh environments, such as fog, underwater vision. Also, this technology has been demonstrated 3D imaging based on range-gated imaging. In this paper, a robot system to monitor structures in invisible fog environment is developed using an active range-gated imaging technique. The system consists of an ultra-short pulse laser device and a highly sensitive imaging sensor. The developed vision system is carried out to monitor objects in invisible fog environment. The experimental result of this newly approach vision system is described in this paper. To see invisible objects in fog

A heavy sea fog event over the Yellow Sea in March 2005: Analysis and numerical modeling

Science.gov (United States)

Gao, Shanhong; Lin, Hang; Shen, Biao; Fu, Gang

2007-02-01

In this paper, a heavy sea fog episode that occurred over the Yellow Sea on 9 March 2005 is investigated. The sea fog patch, with a spatial scale of several hundred kilometers at its mature stage, reduced visibility along the Shandong Peninsula coast to 100 m or much less at some sites. Satellite images, surface observations and soundings at islands and coasts, and analyses from the Japan Meteorology Agency (JMA) are used to describe and analyze this event. The analysis indicates that this sea fog can be categorized as advection cooling fog. The main features of this sea fog including fog area and its movement are reasonably reproduced by the Fifth-generation Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model (MM5). Model results suggest that the formation and evolution of this event can be outlined as: (1) southerly warm/moist advection of low-level air resulted in a strong sea-surface-based inversion with a thickness of about 600 m; (2) when the inversion moved from the warmer East Sea to the colder Yellow Sea, a thermal internal boundary layer (TIBL) gradually formed at the base of the inversion while the sea fog grew in response to cooling and moistening by turbulence mixing; (3) the sea fog developed as the TIBL moved northward and (4) strong northerly cold and dry wind destroyed the TIBL and dissipated the sea fog. The principal findings of this study are that sea fog forms in response to relatively persistent southerly warm/moist wind and a cold sea surface, and that turbulence mixing by wind shear is the primary mechanism for the cooling and moistening the marine layer. In addition, the study of sensitivity experiments indicates that deterministic numerical modeling offers a promising approach to the prediction of sea fog over the Yellow Sea but it may be more efficient to consider ensemble numerical modeling because of the extreme sensitivity to model input.

Reliability in the utility computing era: Towards reliable Fog computing

DEFF Research Database (Denmark)

Madsen, Henrik; Burtschy, Bernard; Albeanu, G.

2013-01-01

This paper considers current paradigms in computing and outlines the most important aspects concerning their reliability. The Fog computing paradigm as a non-trivial extension of the Cloud is considered and the reliability of the networks of smart devices are discussed. Combining the reliability...... requirements of grid and cloud paradigms with the reliability requirements of networks of sensor and actuators it follows that designing a reliable Fog computing platform is feasible....

Characteristics of fog and fogwater fluxes in a Puerto Rican elfin cloud

NARCIS (Netherlands)

Eugster, W.; Burkard, R.; Holwerda, F.; Scatena, F.N.; Bruijnzeel, L.A.

2006-01-01

The Luquillo Mountains of northeastern Puerto Rico harbours important fractions of tropical montane cloud forests. Although it is well known that the frequent occurrence of dense fog is a common climatic characteristic of cloud forests around the world, it is poorly understood how fog processes

Further observations on London fog

Energy Technology Data Exchange (ETDEWEB)

Waller, R E; Lawther, P J

1957-01-01

The degree of illness in a group of people with bonchitis or emphysema residing in London during the winter of 1955--56 was monitored by personal diary methods. Concentration of smoke was related to degree of illness, with rapid response at onset and slow recovery. Wet fogs were no worse than dry ones.

An Extensional Characterization of Lambda-Lifting and Lambda-Dropping

DEFF Research Database (Denmark)

Danvy, Olivier

1999-01-01

Lambda-lifting and lambda-dropping respectively transform a block-structured functional program into recursive equations and vice versa. Lambda-lifting was developed in the early 80’s, whereas lambda-dropping is more recent. Both are split into an analysis and a transformation. Published work......, however, has only concentrated on the analysis parts. We focus here on the transformation parts and more precisely on their correctness, which appears never to have been proven. To this end, we define extensional versions of lambda-lifting and lambda-dropping and establish their correctness with respect...

An Extensional Characterization of Lambda-Lifting and Lambda-Dropping

DEFF Research Database (Denmark)

Danvy, Olivier

1998-01-01

Lambda-lifting and lambda-dropping respectively transform a block-structured functional program into recursive equations and vice versa. Lambda-lifting was developed in the early 80’s, whereas lambda-dropping is more recent. Both are split into an analysis and a transformation. Published work......, however, has only concentrated on the analysis parts. We focus here on the transformation parts and more precisely on their correctness, which appears never to have been proven. To this end, we define extensional versions of lambda-lifting and lambda-dropping and establish their correctness with respect...

The Cumulative Lifting Index (CULI) for the Revised NIOSH Lifting Equation: Quantifying Risk for Workers With Job Rotation.

Science.gov (United States)

Garg, Arun; Kapellusch, Jay M

2016-08-01

The objectives were to: (a) develop a continuous frequency multiplier (FM) for the Revised NIOSH Lifting Equation (RNLE) as a function of lifting frequency and duration of a lifting task, and (b) describe the Cumulative Lifting Index (CULI), a methodology for estimating physical exposure to workers with job rotation. The existing FM for the RNLE (FME) does not differentiate between task duration >2 hr and <8 hr, which makes quantifying physical exposure to workers with job rotation difficult and presents challenges to job designers. Using the existing FMs for 1, 2, and 8 hr of task durations, we developed a continuous FM (FMP) that extends to 12 hr per day. We simulated 157,500 jobs consisting of two tasks each and, using different combinations of Frequency Independent Lifting Index, lifting frequency and duration of lifting. Biomechanical stresses were estimated using the CULI, time-weighted average (TWA), and peak exposure. The median difference between FME and FMP was ±1% (range: 0%-15%). Compared to CULI, TWA underestimated risk of low-back pain (LBP) for 18% to 30% of jobs, and peak exposure for an assumed 8-hr work shift overestimated risk of LBP for 20% to 25% of jobs. Peak task exposure showed 90% agreement with CULI but ignored one of two tasks. The CULI partially addressed the underestimation of physical exposure using the TWA approach and overestimation of exposure using the peak-exposure approach. The proposed FM and CULI may provide more accurate physical exposure estimates, and therefore estimated risk of LBP, for workers with job rotation. © 2016, Human Factors and Ergonomics Society.

A Secure and Verifiable Outsourced Access Control Scheme in Fog-Cloud Computing.

Science.gov (United States)

Fan, Kai; Wang, Junxiong; Wang, Xin; Li, Hui; Yang, Yintang

2017-07-24

With the rapid development of big data and Internet of things (IOT), the number of networking devices and data volume are increasing dramatically. Fog computing, which extends cloud computing to the edge of the network can effectively solve the bottleneck problems of data transmission and data storage. However, security and privacy challenges are also arising in the fog-cloud computing environment. Ciphertext-policy attribute-based encryption (CP-ABE) can be adopted to realize data access control in fog-cloud computing systems. In this paper, we propose a verifiable outsourced multi-authority access control scheme, named VO-MAACS. In our construction, most encryption and decryption computations are outsourced to fog devices and the computation results can be verified by using our verification method. Meanwhile, to address the revocation issue, we design an efficient user and attribute revocation method for it. Finally, analysis and simulation results show that our scheme is both secure and highly efficient.

A Secure and Verifiable Outsourced Access Control Scheme in Fog-Cloud Computing

Science.gov (United States)

Fan, Kai; Wang, Junxiong; Wang, Xin; Li, Hui; Yang, Yintang

2017-01-01

With the rapid development of big data and Internet of things (IOT), the number of networking devices and data volume are increasing dramatically. Fog computing, which extends cloud computing to the edge of the network can effectively solve the bottleneck problems of data transmission and data storage. However, security and privacy challenges are also arising in the fog-cloud computing environment. Ciphertext-policy attribute-based encryption (CP-ABE) can be adopted to realize data access control in fog-cloud computing systems. In this paper, we propose a verifiable outsourced multi-authority access control scheme, named VO-MAACS. In our construction, most encryption and decryption computations are outsourced to fog devices and the computation results can be verified by using our verification method. Meanwhile, to address the revocation issue, we design an efficient user and attribute revocation method for it. Finally, analysis and simulation results show that our scheme is both secure and highly efficient. PMID:28737733

An analytical model for backscattered luminance in fog: comparisons with Monte Carlo computations and experimental results

International Nuclear Information System (INIS)

Taillade, Frédéric; Dumont, Eric; Belin, Etienne

2008-01-01

We propose an analytical model for backscattered luminance in fog and derive an expression for the visibility signal-to-noise ratio as a function of meteorological visibility distance. The model uses single scattering processes. It is based on the Mie theory and the geometry of the optical device (emitter and receiver). In particular, we present an overlap function and take the phase function of fog into account. The results of the backscattered luminance obtained with our analytical model are compared to simulations made using the Monte Carlo method based on multiple scattering processes. An excellent agreement is found in that the discrepancy between the results is smaller than the Monte Carlo standard uncertainties. If we take no account of the geometry of the optical device, the results of the model-estimated backscattered luminance differ from the simulations by a factor 20. We also conclude that the signal-to-noise ratio computed with the Monte Carlo method and our analytical model is in good agreement with experimental results since the mean difference between the calculations and experimental measurements is smaller than the experimental uncertainty

Normalized Lift: An Energy Interpretation of the Lift Coefficient Simplifies Comparisons of the Lifting Ability of Rotating and Flapping Surfaces

OpenAIRE

Burgers, Phillip; Alexander, David E.

2012-01-01

For a century, researchers have used the standard lift coefficient C(L) to evaluate the lift, L, generated by fixed wings over an area S against dynamic pressure, ½ρv(2), where v is the effective velocity of the wing. Because the lift coefficient was developed initially for fixed wings in steady flow, its application to other lifting systems requires either simplifying assumptions or complex adjustments as is the case for flapping wings and rotating cylinders.This paper interprets the standar...

Organic compounds in radiation fogs in Davis (California)

Science.gov (United States)

Herckes, Pierre; Hannigan, Michael P.; Trenary, Laurie; Lee, Taehyoung; Collett, Jeffrey L.

New stainless steel active fogwater collectors were designed and used in Davis (CA, USA) to collect fogwater for the speciation of organic matter. Organic compounds in fog samples were extracted by liquid-liquid extraction and analyzed by gas chromatography coupled to mass spectrometry. Numerous organic compounds, including various alkanes, polycyclic aromatic hydrocarbons (PAH) and alkanoic acids, have been identified in the fogwater samples. Higher molecular weight (MW) compounds are preferentially associated with an insoluble phase inside the fog drops, whereas lower molecular weight and more polar compounds are found predominantly in the dissolved phase. Concentrations in the dissolved phase were sometimes much higher than estimated by the compounds' aqueous solubilities.

Prediction of Peak Back Compressive Forces as a Function of Lifting Speed and Compressive Forces at Lift Origin and Destination - A Pilot Study

Directory of Open Access Journals (Sweden)

Kasey O. Greenland

2011-09-01

Conclusion: SODA under-predict both static and dynamic peak back-compressive force values. Peak values are highly predictable and could be readily determined using back-compressive force assessments at the origin and destination of a lifting task. This could be valuable for enhancing job design and analysis in the workplace and for large-scale studies where a full analysis of each lifting task is not feasible.

Quadratic Interpolation and Linear Lifting Design

Directory of Open Access Journals (Sweden)

Joel Solé

2007-03-01

Full Text Available A quadratic image interpolation method is stated. The formulation is connected to the optimization of lifting steps. This relation triggers the exploration of several interpolation possibilities within the same context, which uses the theory of convex optimization to minimize quadratic functions with linear constraints. The methods consider possible knowledge available from a given application. A set of linear equality constraints that relate wavelet bases and coefficients with the underlying signal is introduced in the formulation. As a consequence, the formulation turns out to be adequate for the design of lifting steps. The resulting steps are related to the prediction minimizing the detail signal energy and to the update minimizing the l2-norm of the approximation signal gradient. Results are reported for the interpolation methods in terms of PSNR and also, coding results are given for the new update lifting steps.

Detection of ground fog in mountainous areas from MODIS (Collection 051) daytime data using a statistical approach

Science.gov (United States)

Schulz, Hans Martin; Thies, Boris; Chang, Shih-Chieh; Bendix, Jörg

2016-03-01

The mountain cloud forest of Taiwan can be delimited from other forest types using a map of the ground fog frequency. In order to create such a frequency map from remotely sensed data, an algorithm able to detect ground fog is necessary. Common techniques for ground fog detection based on weather satellite data cannot be applied to fog occurrences in Taiwan as they rely on several assumptions regarding cloud properties. Therefore a new statistical method for the detection of ground fog in mountainous terrain from MODIS Collection 051 data is presented. Due to the sharpening of input data using MODIS bands 1 and 2, the method provides fog masks in a resolution of 250 m per pixel. The new technique is based on negative correlations between optical thickness and terrain height that can be observed if a cloud that is relatively plane-parallel is truncated by the terrain. A validation of the new technique using camera data has shown that the quality of fog detection is comparable to that of another modern fog detection scheme developed and validated for the temperate zones. The method is particularly applicable to optically thinner water clouds. Beyond a cloud optical thickness of ≈ 40, classification errors significantly increase.

Spatial and temporal patterns of cloud cover and fog inundation in coastal California: Ecological implications

Science.gov (United States)

Rastogi, Bharat; Williams, A. Park; Fischer, Douglas T.; Iacobellis, Sam F.; McEachern, A. Kathryn; Carvalho, Leila; Jones, Charles Leslie; Baguskas, Sara A.; Still, Christopher J.

2016-01-01

The presence of low-lying stratocumulus clouds and fog has been known to modify biophysical and ecological properties in coastal California where forests are frequently shaded by low-lying clouds or immersed in fog during otherwise warm and dry summer months. Summer fog and stratus can ameliorate summer drought stress and enhance soil water budgets, and often have different spatial and temporal patterns. Here we use remote sensing datasets to characterize the spatial and temporal patterns of cloud cover over California’s northern Channel Islands. We found marine stratus to be persistent from May through September across the years 2001-2012. Stratus clouds were both most frequent and had the greatest spatial extent in July. Clouds typically formed in the evening, and dissipated by the following early afternoon. We present a novel method to downscale satellite imagery using atmospheric observations and discriminate patterns of fog from those of stratus and help explain patterns of fog deposition previously studied on the islands. The outcomes of this study contribute significantly to our ability to quantify the occurrence of coastal fog at biologically meaningful spatial and temporal scales that can improve our understanding of cloud-ecosystem interactions, species distributions and coastal ecohydrology.

Cloud and fog computing in 5G mobile networks emerging advances and applications

CERN Document Server

Markakis, Evangelos; Mavromoustakis, Constandinos X; Pallis, Evangelos

2017-01-01

This book focuses on the challenges and solutions related to cloud and fog computing for 5G mobile networks, and presents novel approaches to the frameworks and schemes that carry out storage, communication, computation and control in the fog/cloud paradigm.

Automatic fog detection for public safety by using camera images

Science.gov (United States)

Pagani, Giuliano Andrea; Roth, Martin; Wauben, Wiel

2017-04-01

Fog and reduced visibility have considerable impact on the performance of road, maritime, and aeronautical transportation networks. The impact ranges from minor delays to more serious congestions or unavailability of the infrastructure and can even lead to damage or loss of lives. Visibility is traditionally measured manually by meteorological observers using landmarks at known distances in the vicinity of the observation site. Nowadays, distributed cameras facilitate inspection of more locations from one remote monitoring center. The main idea is, however, still deriving the visibility or presence of fog by an operator judging the scenery and the presence of landmarks. Visibility sensors are also used, but they are rather costly and require regular maintenance. Moreover, observers, and in particular sensors, give only visibility information that is representative for a limited area. Hence the current density of visibility observations is insufficient to give detailed information on the presence of fog. Cameras are more and more deployed for surveillance and security reasons in cities and for monitoring traffic along main transportation ways. In addition to this primary use of cameras, we consider cameras as potential sensors to automatically identify low visibility conditions. The approach that we follow is to use machine learning techniques to determine the presence of fog and/or to make an estimation of the visibility. For that purpose a set of features are extracted from the camera images such as the number of edges, brightness, transmission of the image dark channel, fractal dimension. In addition to these image features, we also consider meteorological variables such as wind speed, temperature, relative humidity, and dew point as additional features to feed the machine learning model. The results obtained with a training and evaluation set consisting of 10-minute sampled images for two KNMI locations over a period of 1.5 years by using decision trees methods

On the enrichment of hydrophobic organic compounds in fog droplets

Science.gov (United States)

Valsaraj, K. T.; Thoma, G. J.; Reible, D. D.; Thibodeaux, L. J.

The unusual degree of enrichment of hydrophobic organics in fogwater droplets reported by several investigators can be interpreted as a result of (a) the effects of temperature correction on the reported enrichment factors, (b) the effects of colloidal organic matter (both filterable and non-filterable) in fog water and (c) the effects of the large air-water interfacial adsorption of neutral hydrophobic organics on the tiny fog droplets. The enrichment factor was directly correlated to the hydrophobicity (or the activity coefficient in water) of the compounds, as indicated by their octanol-water partition constants. Compounds with large octanol-water partition coefficients (high activity coefficients in water) showed the largest enrichment. Available experimental data on the adsorption of hydrophobic compounds at the air-water interface and on colloidal organic carbon were used to show that the large specific air-water interfacial areas of fog droplets contribute significantly to the enrichment factor.

Fog composition at Baengnyeong Island in the eastern Yellow Sea: detecting markers of aqueous atmospheric oxidations

Science.gov (United States)

Boris, A. J.; Lee, T.; Park, T.; Choi, J.; Seo, S. J.; Collett, J. L., Jr.

2016-01-01

Samples of fog water were collected at Baengnyeong Island (BYI) in the Yellow Sea during the summer of 2014. The most abundant chemical species in the fog water were NH4+ (mean of 2220 µM), NO3- (1260 µM), SO4-2 (730 µM), and Na+ (551 µM), with substantial contributions from other species consistent with marine and biomass burning influence on some dates. The pH of the samples ranged between 3.48 and 5.00, with a mean of 3.94, intermediate within pH values of fog/cloud water reported previously in Southeast Asia. Back trajectories (72 h) showed that high relative humidity ( > 80 %) was encountered upwind of the sampling site by all but one of the sampled air masses, and that the fog composition at BYI can be impacted by several different source regions, including the Sea of Japan, southeastern China, northeastern China, and the East China Sea. Sulfur in the collected fog was highly oxidized: low S(IV) concentrations were measured (mean of 2.36 µM) in contrast to SO4-2 and in contrast to fog/cloud S(IV) concentrations from pollutant source regions; organosulfate species were also observed and were most likely formed through aging of mainly biogenic volatile organic compounds. Low-molecular-mass organic acids were major contributors to total organic carbon (TOC; 36-69 %), comprising a fraction of TOC at the upper end of that seen in fogs and clouds in other polluted environments. Large contributions were observed from not only acetic and formic acids but also oxalic, succinic, maleic, and other organic acids that can be produced in aqueous atmospheric organic processing (AAOP) reactions. These samples of East Asian fog water containing highly oxidized components represent fog downwind of pollutant sources and can provide new insight into the fate of regional emissions. In particular, these samples demonstrate the result of extensive photochemical aging during multiday transport, including oxidation within wet aerosols and fogs.

Near-real time Monitoring of the widespread winter Fog over the Indo-Gangetic Plains using satellite data

Science.gov (United States)

Patil, D. L.; Gautam, R.; Rizvi, S.; Singh, M. K.

2016-12-01

The persistent and widespread winter fog impacts the Indo-Gangetic Plains (IGP) on an annual basis, disrupting day-to-day lives of millions of people in parts of northern India, Pakistan, Nepal and Bangladesh. The IGP is a densely-populated region located south of the Himalaya, in the northern parts of south Asia. During the past three decades or so, associated with growing population and energy demands, the IGP has witnessed strong upward trends in air pollution, particularly leading to poor air quality in the winter months. Co-occurring with the dense haze over the IGP, severe fog episodes persist throughout the months of December and January. Building on our recent work on satellite-based detection of fog, we have further extended the detection capability towards the development of a near-real time (NRT) fog monitoring system using satellite radiances and products. Here, we use multi-spectral radiances and aerosol/cloud retrievals from Terra/Aqua MODIS data for NRT fog monitoring over the IGP for both daytime as well as nighttime. Specifically, the nighttime fog detection algorithm employs a bi-spectral brightness temperature difference technique between two spectral channels: 3.9 μm and 11 μm. Our ongoing efforts also include extending fog detection capability in NRT to geostationary satellites, for providing continuous monitoring of the onset, evolution and spatial-temporal variation of fog, as well as the geospatial integration of surface meteorological observations of visibility, relative humidity, temperature. We anticipate that the ongoing and future development of a fog monitoring system may be of particular assistance to air and rail transportation management, as well as of general interest to the public. The outputs of fog detection algorithm and related aerosol/cloud parameters are operationally disseminated via http://fogsouthasia.com/.

Face-Lift

Science.gov (United States)

... or sun damage, you might also consider a skin-resurfacing procedure. A face-lift can be done in combination with some other cosmetic procedures, such as a brow lift or eyelid surgery. Why it's done As you get older, your facial skin changes — sagging and becoming loose. This can make ...

Lift-and-fill face lift: integrating the fat compartments.

Science.gov (United States)

Rohrich, Rod J; Ghavami, Ashkan; Constantine, Fadi C; Unger, Jacob; Mojallal, Ali

2014-06-01

Recent discovery of the numerous fat compartments of the face has improved our ability to more precisely restore facial volume while rejuvenating it through differential superficial musculoaponeurotic system treatment. Incorporation of selective fat compartment volume restoration along with superficial musculoaponeurotic system manipulation allows for improved control in recontouring while addressing one of the key problems in facial aging, namely, volume deflation. This theory was evaluated by assessing the contour changes from simultaneous face "lifting" and "filling" through fat compartment-guided facial fat transfer. A review of 100 face-lift patients was performed. All patients had an individualized component face lift with fat grafting to the nasolabial fold, deep malar, and high/lateral malar fat compartment locations. Photographic analysis using a computer program was conducted on oblique facial views preoperatively and postoperatively, to obtain the most projected malar contour point. Two independent observers visually evaluated the malar prominence and nasolabial fold improvements based on standardized photographs. Nasolabial fold improved by at least one grade in 81 percent and by over one grade in 11 percent. Malar prominence average projection increase was 13.47 percent and the average amount of lift was 12.24 percent. The malar prominence score improved by at least one grade in 62 percent of the patients postoperatively, and 9 percent had a greater than one grade improvement. Twenty-eight percent of the patients had a convex malar prominence postoperatively compared with 6 percent preoperatively. Malar prominence improved by at least one grade in 63 percent and by over one grade in 10 percent. The lift-and-fill face lift merges two key concepts in facial rejuvenation: (1) effective tissue manipulation by means of lifting and tightening in differential vectors according to original facial asymmetry and shape; and (2) selective fat compartment filling

Optimization of strawberry disinfection by fogging of a mixture of peracetic acid and hydrogen peroxide based on microbial reduction, color and phytochemicals retention.

Science.gov (United States)

Van de Velde, Franco; Vaccari, María Celia; Piagentini, Andrea Marcela; Pirovani, María Élida

2016-09-01

The fogging of strawberries using a environmentally friendly sanitizer mixture of peracetic acid (5%) and hydrogen peroxide (20%) was performed in a model chamber and modeled as a function of the concentration (3.4, 20.0, 60.0, 100.0 and 116.6 µL sanitizer L(-) (1) air chamber) and the treatment time (5.7, 15.0, 37.5, 60.0 and 69.3 min). The sanitizer fogging was adequate for reducing total mesophilic microbial and yeasts and moulds counts of fruits until seven days of storage at 2℃. However, sanitizer oxidant properties adversely affected the content of total anthocyanins, total phenolics, vitamin C, and antioxidant capacity to various degrees, with some deleterious changes in the fruits color, depending on the fogging conditions. A multiple numeric response optimization was developed based on 2.0 log microbiological reduction, maximum phytochemicals and antioxidant capacity retentions, with no changes in the fruits color, being the optimal fogging conditions achieved: 10.1 µL sanitizer L(-1) air chamber and 29.6 min. The fogging of strawberries at these conditions may represent a promising postharvest treatment option for extending their shelf-life without affecting their sensory quality and bioactive properties. © The Author(s) 2016.

A Molecular Explanation of How the Fog Is Produced When Dry Ice Is Placed in Water

Science.gov (United States)

Kuntzleman, Thomas S.; Ford, Nathan; No, Jin-Hwan; Ott, Mark E.

2015-01-01

Everyone enjoys seeing the cloudy white fog generated when solid carbon dioxide (dry ice) is placed in water. Have you ever wondered what physical and chemical processes occur to produce this fog? When asked this question, many chemical educators suggest that the fog is produced when atmospheric water vapor condenses on cold carbon dioxide gas…

Fractionation of airborne particulate-bound elements in haze-fog episode and associated health risks in a megacity of southeast China

International Nuclear Information System (INIS)

Li, Huiming; Wang, Qin'geng; Shao, Min; Wang, Jinhua; Wang, Cheng; Sun, Yixuan; Qian, Xin; Wu, Hongfei; Yang, Meng; Li, Fengying

2016-01-01

Haze caused by high particulate matter loadings is an important environmental issue. PM_2_._5 was collected in Nanjing, China, during a severe haze–fog event and clear periods. The particulate-bound elements were chemically fractionated using sequential extractions. The average PM_2_._5 concentration was 3.4 times higher during haze–fog (96–518 μg/m"3) than non-haze fog periods (49–142 μg/m"3). Nearly all elements showed significantly higher concentrations during haze–fog than non-haze fog periods. Zn, As, Pb, Cd, Mo and Cu were considered to have higher bioavailability and enrichment degree in the atmosphere. Highly bioavailable fractions of elements were associated with high temperatures. The integrated carcinogenic risk for two possible scenarios to individuals exposed to metals was higher than the accepted criterion of 10"−"6, whereas noncarcinogenic risk was lower than the safe level of 1. Residents of a city burdened with haze will incur health risks caused by exposure to airborne metals. - Highlights: • PM_2_._5 concentration was 3.4 times higher during haze-fog than non-haze fog days. • Nearly all metals had higher contents during haze-fog than non-haze fog days. • Zn, As, Pb, Cd, Mo and Cu had high bioavailability and enrichment level in PM_2_._5. • Highly bioavailable fractions of elements were associated with high temperatures. • Health risk was assessed combined with metal forms in haze-fog and non-haze fog days. - Fractionation of airborne particulate-bound metals and its contribution to health risks during haze-fog and non-haze fog periods were studied from a typical megacity of Southeast China.

A Behavior of Strobe Light in Non-Visibility (Dense Fog) Environments

Energy Technology Data Exchange (ETDEWEB)

Cho, Jai Wan; Choi, Young Soo; Jeong, Kyung Min [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-10-15

In this study, a strobe light was used to understand the behavior of light in an aerosol-like non-visibility environment. Fog was injected into a vinyl pleated cylindrical fog box that is 1 m in diameter and 5.5 m in length. After the fog concentration became saturated in the fog box, the strobe light was set off at regular time intervals until the fog particles almost dissipated in the box. Images of the behavior of the light from the strobe were taken from outside of the fog box with a digital camera in line with the strobe light sync signal. In the case of a DBA (or severe accident) of the nuclear power plant accident, coolant should be injected over the reactor pressure vessel to cool the reactor core. Cold coolant that has been poured into the reactor pressure vessel would be discharged through the nozzles of the core spray system or through pipelines in the fire protection system. The discharging cold coolant would impact high temperature structures with surface temperatures of around 250 .deg. C or higher, such as the reactor pressure vessel that surrounds the reactor core, and then evaporate and turn into steam. The steam cools while forming mist (aerosol including radioactivity), which can cause a sharp drop in visibility. Assuming that a robot has been deployed to manage and mitigate the DBA (or severe accident) at the nuclear power plant, the robot must perform its task in a non-visibility environment. A color CCD/CMOS camera corresponding to visible wavelength (400 - 700 nm) can be attached to the robot for observation and navigation. The camera needs lights in order to secure a clear field of view. Generally, the aperture of a lens is correlated to the intensity of illumination. The brighter the light, the smaller the aperture can be. If the aperture becomes narrower to the size of a pin hole, a clearer image in deep focus can be obtained. As the aperture decreases in the half, the required amount of light doubles. The observed behavior of the strobe

A Behavior of Strobe Light in Non-Visibility (Dense Fog) Environments

International Nuclear Information System (INIS)

Cho, Jai Wan; Choi, Young Soo; Jeong, Kyung Min

2015-01-01

In this study, a strobe light was used to understand the behavior of light in an aerosol-like non-visibility environment. Fog was injected into a vinyl pleated cylindrical fog box that is 1 m in diameter and 5.5 m in length. After the fog concentration became saturated in the fog box, the strobe light was set off at regular time intervals until the fog particles almost dissipated in the box. Images of the behavior of the light from the strobe were taken from outside of the fog box with a digital camera in line with the strobe light sync signal. In the case of a DBA (or severe accident) of the nuclear power plant accident, coolant should be injected over the reactor pressure vessel to cool the reactor core. Cold coolant that has been poured into the reactor pressure vessel would be discharged through the nozzles of the core spray system or through pipelines in the fire protection system. The discharging cold coolant would impact high temperature structures with surface temperatures of around 250 .deg. C or higher, such as the reactor pressure vessel that surrounds the reactor core, and then evaporate and turn into steam. The steam cools while forming mist (aerosol including radioactivity), which can cause a sharp drop in visibility. Assuming that a robot has been deployed to manage and mitigate the DBA (or severe accident) at the nuclear power plant, the robot must perform its task in a non-visibility environment. A color CCD/CMOS camera corresponding to visible wavelength (400 - 700 nm) can be attached to the robot for observation and navigation. The camera needs lights in order to secure a clear field of view. Generally, the aperture of a lens is correlated to the intensity of illumination. The brighter the light, the smaller the aperture can be. If the aperture becomes narrower to the size of a pin hole, a clearer image in deep focus can be obtained. As the aperture decreases in the half, the required amount of light doubles. The observed behavior of the strobe

Intercomparison of fog water samplers

Science.gov (United States)

Schell, Dieter; Georgii, Hans-Walter; Maser, Rolf; Jaeschke, Wolfgang; Arends, Beate G.; Kos, Gerard P. A.; Winkler, Peter; Schneider, Thomas; Berner, Axel; Kruisz, Christian

1992-11-01

During the Po Valley Fog Experiment 1989, two fogwater collectors were operated simultaneously at the ground and the results were compared to each other. The chemical analyses of the samples as well as the collection efficiencies showed remarkable differences between both collectors. Some differences in the solute concentrations in the samples of both collectors could be expected due to small differences in the 50-percent cut-off diameters. The large differences in the collection efficiencies however cannot be explained by these small variations of d sub 50, because normally only a small fraction of the water mass is concentrated in the size range of 5-7-micron droplets. It is shown that it is not sufficient to characterize a fogwater collector only by its cut-off diameter. The results of several wind tunnel calibration tests show that the collection efficiencies of the fogwater collectors are a function of windspeed and shape of the droplet spectra.

Fog reduces transpiration in tree species of the Canarian relict heath-laurel cloud forest (Garajonay National Park, Spain).

Science.gov (United States)

Ritter, Axel; Regalado, Carlos M; Aschan, Guido

2009-04-01

The ecophysiologic role of fog in the evergreen heath-laurel 'laurisilva' cloud forests of the Canary Islands has not been unequivocally demonstrated, although it is generally assumed that fog water is important for the survival and the distribution of this relict paleoecosystem of the North Atlantic Macaronesian archipelagos. To determine the role of fog in this ecosystem, we combined direct transpiration measurements of heath-laurel tree species, obtained with Granier's heat dissipation probes, with micrometeorological and artificial fog collection measurements carried out in a 43.7-ha watershed located in the Garajonay National Park (La Gomera, Canary Islands, Spain) over a 10-month period. Median ambient temperature spanned from 7 to 15 degrees C under foggy conditions whereas higher values, ranging from 9 to 21 degrees C, were registered during fog-free periods. Additionally, during the periods when fog water was collected, global solar radiation values were linearly related (r2=0.831) to those under fog-free conditions, such that there was a 75+/-1% reduction in median radiation in response to fog. Fog events greatly reduced median diurnal tree transpiration, with rates about 30 times lower than that during fog-free conditions and approximating the nighttime rates in both species studied (the needle-like leaf Erica arborea L. and the broadleaf Myrica faya Ait.). This large decrease in transpiration in response to fog was independent of the time of the day, tree size and species and micrometeorological status, both when expressed on a median basis and in cumulative terms for the entire 10-month measuring period. We conclude that, in contrast to the turbulent deposition of fog water droplets on the heath-laurel species, which may be regarded as a localized hydrological phenomenon that is important for high-altitude wind-exposed E. arborea trees, the cooler, wetter and shaded microenvironment provided by the cloud immersion belt represents a large-scale effect

A field investigation of physical and chemical mechanisms affecting pollutant concentrations in fog droplets

OpenAIRE

Jacob, Daniel J.; Waldman, Jed. M.; Munger, J. William; Hoffmann, Michael R.

2011-01-01

High ionic loadings were found in fogwater collected at Bakersfield. California during an extended stagnation episode. The major ions were NH4+ NO3-, and SO42-, with concentrations usually in the millimolar range. Droplet growth played an important rôle in determining fogwater concentrations. The amount of solute decreased substantially over the course of each fog event; this was attributed, at least in part, to deposition of fog droplets on surfaces. The occurrence of dense fogs thus seemed ...

Ecosystem properties self-organize in response to a directional fog-vegetation interaction.

Science.gov (United States)

Stanton, Daniel E; Armesto, Juan J; Hedin, Lars O

2014-05-01

Feedbacks between vegetation and resource inputs can lead to the local, self-organization of ecosystem properties. In particular, feedbacks in response to directional resources (e.g., coastal fog, slope runoff) can create complex spatial patterns, such as vegetation banding. Although similar feedbacks are thought to be involved in the development of ecosystems, clear empirical examples are rare. We created a simple model of a fog-influenced, temperate rainforest in central Chile, which allows the comparison of natural banding patterns to simulations of various putative mechanisms. We show that only feedbacks between plants and fog were able to replicate the characteristic distributions of vegetation, soil water, and soil nutrients observed in field transects. Other processes, such as rainfall, were unable to match these diagnostic distributions. Furthermore, fog interception by windward trees leads to increased downwind mortality, leading to progressive extinction of the leeward edge. This pattern of ecosystem development and decay through self-organized processes illustrates, on a relatively small spatial and temporal scale, the patterns predicted for ecosystem evolution.

Impact of sophisticated fog spray models on accident analyses

International Nuclear Information System (INIS)

Roblyer, S.P.; Owzarski, P.C.

1978-01-01

The N-Reactor confinement system release dose to the public in a postulated accident is reduced by washing the confinement atmosphere with fog sprays. This allows a low pressure release of confinement atmosphere containing fission products through filters and out an elevated stack. The current accident analysis required revision of the CORRAL code and other codes such as CONTEMPT to properly model the N Reactor confinement into a system of multiple fog-sprayed compartments. In revising these codes, more sophisticated models for the fog sprays and iodine plateout were incorporated to remove some of the conservatism of steam condensing rate, fission product washout and iodine plateout than used in previous studies. The CORRAL code, which was used to describe the transport and deposition of airborne fission products in LWR containment systems for the Rasmussen Study, was revised to describe fog spray removal of molecular iodine (I 2 ) and particulates in multiple compartments for sprays having individual characteristics of on-off times, flow rates, fall heights, and drop sizes in changing containment atmospheres. During postulated accidents, the code determined the fission product removal rates internally rather than from input decontamination factors. A discussion is given of how the calculated plateout and washout rates vary with time throughout the analysis. The results of the accident analyses indicated that more credit could be given to fission product washout and plateout. An important finding was that the release of fission products to the atmosphere and adsorption of fission products on the filters were significantly lower than previous studies had indicated

Functional reorganization of the locomotor network in Parkinson patients with freezing of gait.

Directory of Open Access Journals (Sweden)

Brett W Fling

Full Text Available Freezing of gait (FoG is a transient inability to initiate or maintain stepping that often accompanies advanced Parkinson's disease (PD and significantly impairs mobility. The current study uses a multimodal neuroimaging approach to assess differences in the functional and structural locomotor neural network in PD patients with and without FoG and relates these findings to measures of FoG severity. Twenty-six PD patients and fifteen age-matched controls underwent resting-state functional magnetic resonance imaging and diffusion tensor imaging along with self-reported and clinical assessments of FoG. After stringent movement correction, fifteen PD patients and fourteen control participants were available for analysis. We assessed functional connectivity strength between the supplementary motor area (SMA and the following locomotor hubs: 1 subthalamic nucleus (STN, 2 mesencephalic and 3 cerebellar locomotor region (MLR and CLR, respectively within each hemisphere. Additionally, we quantified structural connectivity strength between locomotor hubs and assessed relationships with metrics of FoG. FoG+ patients showed greater functional connectivity between the SMA and bilateral MLR and between the SMA and left CLR compared to both FoG- and controls. Importantly, greater functional connectivity between the SMA and MLR was positively correlated with i clinical, ii self-reported and iii objective ratings of freezing severity in FoG+, potentially reflecting a maladaptive neural compensation. The current findings demonstrate a re-organization of functional communication within the locomotor network in FoG+ patients whereby the higher-order motor cortex (SMA responsible for gait initiation communicates with the MLR and CLR to a greater extent than in FoG- patients and controls. The observed pattern of altered connectivity in FoG+ may indicate a failed attempt by the CNS to compensate for the loss of connectivity between the STN and SMA and may reflect a

A field study on chemistry, S(IV) oxidation rates and vertical transport during fog conditions

Science.gov (United States)

Joos, F.; Baltensperger, U.

An extensive fog study was carried out in the central plateu of Switzerland. Ninety-seven fog samples were collected along with aerosol filter and cascade impactor samples, and measurements of O 3, SO 2, NO, NO x, PAN, temperature, and wind speed and direction. Maximum levels in fogwater were 4.3, 4.4., 0.033, 1.7, 0.5, 0.024 and 9.2 mmol ℓ -1 for Cl -, NO 3-, NO 2-, SO 42-, S(IV), oxalate and NH 4+, respectively. pH varied between 2.9 and 7.1. Sixteen additional elements were determined in the fog samples by ICP. The sum of the concentrations of SO 42- and S(IV) agreed very with the total sulfur concentration as determined by ICP. A substantial excess of S(IV) (up to 0.2 mmol ℓ -1) compared to Henry and acid-base equilibrium calculations was found, which can probably be attributed to complex formations with aldehydes. S(IV) oxidation rates of up to 650 nmol ℓ -1 s -1 with ozone and of up to 100 nmol ℓ -1 s -1 with NO 2 were calculated. S(IV) oxidation due to PAN, NO 2- and Fe(III) was of minor importance. A substantial fraction of the major ions was present in the intersitial aerosol (aerosol particles < 4 μm) even during fog conditions. High correlations were found for NH 4+, NO 32-. From their ratios in the fog water and the aerosol (< 4 μm) it could be concluded that at least 40% of NO 3- and 20% of NH 4+ in fog water was due to gas phase scavenging. Increasing concentrations in fog water were found during fog dissipation. Concentrations decreased with increasing height. A vertical transport model including turbulent diffusion and droplet sedimentation is introduced, which matches the experimental data of this vertical profile.

Electron-microscope study of cloud and fog nuclei

Energy Technology Data Exchange (ETDEWEB)

Ogiwara, S; Okita, T

1952-01-01

Droplets of clouds on a mountain and of fog in an urban area were captured and the form, nature and size of their nuclei were studied by means of an electron-microscope and by a chamber of constant humidity. These nuclei have similar form and nature to the hygroscopic particles in haze and to the artificially produced combustion particles. No sea-salt nuclei were found in our observations, therefore, sea-spray appears to be an insignificant source of condensation nuclei. It was found that both the cloud and the fog nuclei originated in combustion products which were the mixture of hygroscopic and non-hygroscopic substances, and that the greater part of the nuclei did not contain pure sulfuric acid.

Chemical characterization of fog and rain water collected at the eastern Andes cordillera

Science.gov (United States)

Beiderwieden, E.; Wrzesinsky, T.; Klemm, O.

2005-09-01

During a three month period in 2003 and 2004, the chemistry of fog and rainwater were studied at the "El Tiro" site in a tropical mountain forest ecosystem in Ecuador, South America. The fogwater samples were collected using a passive fog collector, and for the rain water, a standard rain sampler was employed. For all samples, electric conductivity, pH, and the concentrations of NH4+, K+, Na+, Ca2+, Mg2+, Cl-, NO3-, PO43-, and SO42- were measured. For each fog sample, a 5 day back trajectory was calculated by the use of the HYSPLIT model. Two types of trajectories occurred. One type was characterized by advection of air masses from the East over the Amazonian basin, the other trajectory arrived one from the West after significant travel time over the Pacific Ocean. We found considerably higher ion concentrations in fogwater samples than in rain samples. Median pH values are 4.58 for fog water, and 5.26 for the rain samples, respectively. The median electric conductivity was 23 μS cm-1 for the fog and 6 μS cm-1 for the rain. The continent samples exhibit higher concentrations of most ions as compared to the pacific samples, but these differences could not be detected statistically.

Experiments with a straightforward model for the spatial forecast of fog/low stratus clearance based on multi-source data

Science.gov (United States)

Reudenbach, Ch; Bendix, J.

1998-09-01

A straightforward model for the spatial calculation of the time of fog clearance is presented which is based on thermodynamic equations, spatial data sets such as NOAA-AVHRR satellite data, Digital Elevation Model, and horizontal and vertical meteorological observations. The model has been tested on two days with extended fog layers within the study area. The local validation of the model reveals an accuracy in fog clearance of 4 minutes by comparing the model result with meteorological observations. A spatial validation by means of a reference NOAA overpass indicates an under-estimation of the fog-covered area by the model of 2.9% at the time of the reference image. Five minutes before reference time, the spatial correspondence of the modelled and the reference fog coverage increases to 98.9%. The temporal deviation of uncoinciding pixels between reference and modelled fog image at reference time is less than ±30 minutes in 68% of the total number of fog-covered pixels and therefore matches the accuracy of local tephigram methods. However, for individual pixels a time error of up to ±60 minutes occurs for the time of fog clearance. Time errors are probably mainly due to an inaccurate estimation of fog thickness.

Lift scheduling organization : Lift Concept for Lemminkainen

OpenAIRE

Mingalimov, Iurii

2015-01-01

The purpose of the work was to make a simple schedule for the main contractors and clients to check and control workflow connected with lifts. It gathers works with electricity, construction, engineering networks, installing equipment and commissioning works. The schedule was carried out during working on the building site Aino in Saint Petersburg in Lemminkӓinen. The duration of work was 5 months. The lift concept in Lemminkӓinen is very well controlled in comparison with other buil...

Lifting strength in two-person teamwork.

Science.gov (United States)

Lee, Tzu-Hsien

2016-01-01

This study examined the effects of lifting range, hand-to-toe distance, and lifting direction on single-person lifting strengths and two-person teamwork lifting strengths. Six healthy males and seven healthy females participated in this study. Two-person teamwork lifting strengths were examined in both strength-matched and strength-unmatched groups. Our results showed that lifting strength significantly decreased with increasing lifting range or hand-to-toe distance. However, lifting strengths were not affected by lifting direction. Teamwork lifting strength did not conform to the law of additivity for both strength-matched and strength-unmatched groups. In general, teamwork lifting strength was dictated by the weaker of the two members, implying that weaker members might be exposed to a higher potential danger in teamwork exertions. To avoid such overexertion in teamwork, members with significantly different strength ability should not be assigned to the same team.

Modelling fog in probabilistic consequence assessment

International Nuclear Information System (INIS)

Underwood, B.Y.

1993-02-01

Earlier work examined the potential influence of foggy weather conditions on the probabilistic assessment of the consequences of accidental releases of radioactive material to the atmosphere (PCA), in particular the impact of a fraction of the released aerosol becoming incorporated into droplets. A major uncertainty emerging from the initial scoping study concerned estimation of the fraction of the released material that would be taken up into droplets. An objective is to construct a method for handling in a PCA context the effect of fog on deposition, basing the method on the experience gained from prior investigations. There are two aspects to explicitly including the effect of fog in PCA: estimating the probability of occurrence of various types of foggy condition and calculating the impact on the conventional end-points of consequence assessment. For the first, a brief outline is given of the use of meteorological data by PCA computer codes, followed by a discussion of some routinely-recorded meteorological parameters that are pertinent to fog, such as the presentweather code and horizontal visibility. Four stylized scenarios are defined to cover a wide range of situations in which particle growth by uptake of water may have an important impact on deposition. A description is then given of the way in which routine meteorological data could be used to flag the presence of each of these conditions in the meteorological data file used by the PCA code. The approach developed to calculate the impact on deposition is pitched at a level of complexity appropriate to the PCA context and reflects the physical constraints of the system and accounts for the specific characteristics of the released aerosol. (Author)

Regional deposition of inhaled fog droplets: preliminary observations

International Nuclear Information System (INIS)

Bowes, S.M. III; Laube, B.L.; Links, J.M.; Frank, R.

1989-01-01

The regional deposition of a monodisperse 10-micron mass median aerodynamic diameter fog was studied in four healthy adult male nonsmokers. The fog was radiolabeled with technetium-99m sulfur colloid to enable detection by an Anger camera of deposited activity in the following regions of the respiratory tract: oropharynx, larynx, trachea, and intrapulmonary airways. Intrapulmonary deposition was further analyzed by computer with inner, intermediate, and outer zones, and within apical, intermediate and basal zones of the right lung. The radiolabeled aerosol was inhaled by mouth through a face-mask with the nasal airway occluded. Respiratory frequency, tidal volume, and jaw position were controlled and were commensurate with the oral component of oronasal breathing during moderate exercise. Deposition in the larynx, trachea, and intrapulmonary airways was a function of the scrubbing efficiency of the oropharynx, which differed substantially among subjects, and ranged from 72 to 99%. The density of the aerosol deposit in the larynx probably exceeded that of any of the subdivisions of the tracheobronchial tree and lung. Within the lung, deposition favored the inner zone (assumed to contain the larger airways) over the outer zone (assumed to be dominated by smaller airways and alveoli). Intrapulmonary aerosol distribution in an elderly subject with borderline evidence of airway obstruction differed from that observed in younger subjects. The possible consequences of altered lung elastic recoil, as may occur with aging, for regional dosimetry is discussed

A comparison of two lifting assessment approaches in patients with chronic low back pain

NARCIS (Netherlands)

Soer, Remko; Poels, Bas J. J.; Geertzen, Jan H. B.; Reneman, Michiel F.

2006-01-01

The Progressive Isoinertial Lifting Evaluation (PILE) and the lifting test of the WorkWell Systems Functional Capacity Evaluation (WWS) are well known as lifting performance tests. The objective of this study was to study whether the PILE and the WWS can be used interchangeably in patients with

Thread-Lift Sutures: Still in the Lift? A Systematic Review of the Literature.

Science.gov (United States)

Gülbitti, Haydar Aslan; Colebunders, Britt; Pirayesh, Ali; Bertossi, Dario; van der Lei, Berend

2018-03-01

In 2006, Villa et al. published a review article concerning the use of thread-lift sutures and concluded that the technique was still in its infancy but had great potential to become a useful and effective procedure for nonsurgical lifting of sagged facial tissues. As 11 years have passed, the authors now performed again a systematic review to determine the real scientific current state of the art on the use of thread-lift sutures. A systematic review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines using the PubMed database and using the Medical Subject Headings search term "Rhytidoplasty." "Rhytidoplasty" and the following entry terms were included by this Medical Subject Headings term: "facelift," "facelifts," "face Lift," "Face Lifts," "Lift," "Face," "Lifts," "Platysmotomy," "Platysmotomies," "Rhytidectomy," "Rhytidectomies," "Platysmaplasty," "and "Platysmaplasties." The Medical Subject Headings term "Rhytidoplasty" was combined with the following search terms: "Barbed suture," "Thread lift," "APTOS," "Suture suspension," "Percutaneous," and "Silhouette suture." RefWorks was used to filter duplicates. Three of the authors (H.A.G., B.C., and B.L.) performed the search independently. The initial search with all search terms resulted in 188 articles. After filtering the duplicates and the articles about open procedures, a total of 41 articles remained. Of these, the review articles, case reports, and letters to the editor were subsequently excluded, as were reports dealing with nonbarbed sutures, such as Vicryl and Prolene with Gore-Tex. This resulted in a total of 12 articles, seven additional articles since the five articles reviewed by Villa et al. The authors' review demonstrated that, within the past decade, little or no substantial evidence has been added to the peer-reviewed literature to support or sustain the promising statement about thread-lift sutures as made by Villa et al. in 2006 in terms of

Haloacetates in fog and rain.

Science.gov (United States)

Römpp, A; Klemm, O; Fricke, W; Frank, H

2001-04-01

Atmospheric haloacetates can arise from photochemical degradation of halogenated hydrocarbons and from direct anthropogenic emissions. Furthermore, there is also evidence of natural sources although these are quantitatively uncertain. As haloacetates are highly soluble in water, hydrometeors are most significant for their deposition. Fogwater (96 samples) and rainwater samples (over 100 samples) were collected from July 1998 to March 1999 at an ecological research site in northeastern Bavaria, Germany. They were analyzed for monofluoroacetate (MFA), difluoroacetate (DFA), trifluoroacetate (TFA), monochloroacetate (MCA), dichloroacetate (DCA), trichloroacetate (TCA), monobromoacetate (MBA), and dibromoacetate (DBA). The major inorganic ions were also determined. High concentrations of up to 11 microg/L MCA, 5 microg/L DCA, 2 microg/L TCA, and 2 microg/L TFA were found in fogwater associated with westerly winds. Backward trajectories were calculated to determine the origin of the air masses. MBA and DBA have highest concentrations in fogwater advected with air originating from the Atlantic, suggesting the marine origin of these two compounds. All analyzed substances show higher average concentrations in fog than in rain. Estimates of the deposition of haloacetates suggest that the contribution of fog may be more important than rain for the total burden of a forest ecosystem.

Fog water collection and reforestation at mountain locations in a western Mediterranean basin region

Science.gov (United States)

Valiente, Ja; Estrela, Mj; Corell, D.; Fuentes, D.; Valdecantos, A.

2010-07-01

Previous studies carried out by the authors have shown the potential of fog water collection at several mountain locations in the Valencia region (western Mediterranean basin). This coastal region features typical conditions for a dry Mediterranean climate characterized by a pluviometric regime ranging from 400 to 600 mm with a strong annual dependence. Dry conditions together with land degradation that frequently results after recurrent fires occurred in the past make a difficult self-recovery for native forest vegetation so that some kind of human intervention is always recommended. In plots reforested with Mediterranean woody species, periods of more than 120 days without significant precipitation (>5 mm) result in mortality rates above 80% during the first summer in the field. The good potential of fog-water collection at certain mountain locations is considered in this study as an easily available water resource for the reforestation of remote areas where native vegetation cannot be reestablished by itself. A large flat panel made of UV-resistant HD-polyethylene monofilament mesh was deployed at a mountain location for bulk fog water harvesting. Water was stored in high-capacity tanks for the whole length of the experimental campaign and small timely water pulses localized deep in the planting holes were conducted during the summer dry periods. Survival rates and seedling performance of two forest tree species, Pinus pinaster and Quercus ilex, were quantified and correlated to irrigation pulses in a reforestation plot that took an area of about 2500 m2 and contained 620 1-year-old plants. Before and concurrently to the flat panel deployment, a passive omnidirectional fog-water collector of cylindrical shape was set in the area in combination to other environmental instruments such as a rain gauge, a wind direction and velocity sensor and a temperature and humidity probe. Proper orientation of the large flat panel was possible once the direction of local winds

Fog composition at Baengnyeong Island in the eastern Yellow Sea: detecting markers of aqueous atmospheric oxidations

Directory of Open Access Journals (Sweden)

A. J. Boris

2016-01-01

Full Text Available Samples of fog water were collected at Baengnyeong Island (BYI in the Yellow Sea during the summer of 2014. The most abundant chemical species in the fog water were NH4+ (mean of 2220 µM, NO3− (1260 µM, SO4−2 (730 µM, and Na+ (551 µM, with substantial contributions from other species consistent with marine and biomass burning influence on some dates. The pH of the samples ranged between 3.48 and 5.00, with a mean of 3.94, intermediate within pH values of fog/cloud water reported previously in Southeast Asia. Back trajectories (72 h showed that high relative humidity ( >  80 % was encountered upwind of the sampling site by all but one of the sampled air masses, and that the fog composition at BYI can be impacted by several different source regions, including the Sea of Japan, southeastern China, northeastern China, and the East China Sea. Sulfur in the collected fog was highly oxidized: low S(IV concentrations were measured (mean of 2.36 µM in contrast to SO4−2 and in contrast to fog/cloud S(IV concentrations from pollutant source regions; organosulfate species were also observed and were most likely formed through aging of mainly biogenic volatile organic compounds. Low-molecular-mass organic acids were major contributors to total organic carbon (TOC; 36–69 %, comprising a fraction of TOC at the upper end of that seen in fogs and clouds in other polluted environments. Large contributions were observed from not only acetic and formic acids but also oxalic, succinic, maleic, and other organic acids that can be produced in aqueous atmospheric organic processing (AAOP reactions. These samples of East Asian fog water containing highly oxidized components represent fog downwind of pollutant sources and can provide new insight into the fate of regional emissions. In particular, these samples demonstrate the result of extensive photochemical aging during multiday transport, including oxidation within wet aerosols and

Evaluation of fog and rain water collected at Delta Barrage, Egypt as a new resource for irrigated agriculture

Science.gov (United States)

Salem, Talaat A.; Omar, Mohie El Din M.; El Gammal, H. A. A.

2017-11-01

Alternative clean water resources are needed in Egypt to face the current water shortage and water quality deterioration. Therefore, this research investigates the suitability of harvesting fog and rain water for irrigation using a pilot fog collector for water quantity, water quality, and economic aspects. A pilot fog collector was installed at one location at Delta Barrage, Egypt. Freeze liquid nitrogen was fixed at the back of the fiberglass sheet to increase the condensation rate. The experiment was conducted during the period from November 2015 to February 2016. In general, all physicochemical variables are observed with higher values in the majority of fog than rain water. The fog is assumed to contain higher concentrations of anthropogenic emissions. TDS in both waters collected are less than 700 mg/l at sodium content less than 60%, classifying these waters as good for various plants under most conditions. In addition, SAR calculated values are less than 3.0 in each of fog and rain water, which proves the water suitability for all irrigated agriculture. Al and Fe concentrations were found common in all samples with values less than the permissible limits of the guidelines. These metals originate from soil material, ash and metal surfaces. The sensitive heavy metals (Cd and Pb) were within the permissible limits of the guideline in fog water, indicating this water is suitable for irrigation. On the contrary, rain water that has heavy metals is not permitted in irrigation water as per the Egyptian law. As per WQI, the rain water is classified as good quality while fog is classified as medium quality. Regarding the water quantity, a significant increase in the harvested fog quantity was observed after cooling the collector surface with freeze liquid nitrogen. The current fog collector produced the lowest water quantity among different fog collectors worldwide. However, these comparative results confirmed that quantity is different from one location to another

A Novel Retinex Algorithm and its Application to Fog-degraded Image Enhancement

Directory of Open Access Journals (Sweden)

Xueyou Hu

2014-07-01

Full Text Available Fog-degraded images enhancement is an important problem in the field of image enhancement and computer vision. To overcome the halo artifact, enhance the contrast and better preserve the color of original image, a novel Multi-Scale Retinex color image enhancement method is proposed in this paper. An adaptive anisotropic Gaussian filtering method and its principle are described. The orientation of the Gaussian filter long axes is determined according to the gradient orientation in the position. The procedure of algorithm is given in this paper and applied in the fog- degraded images enhancement. Finally, by comparison with histogram equalization and Multi-Scale Retinex method, the experimental results show that the proposed method can offer better performance in fog-degraded image enhancement.

The miR-17-92 cluster regulates FOG-2 expression and inhibits proliferation of mouse embryonic cardiomyocytes

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Rui Xiang

2012-02-01

Full Text Available MicroRNAs (miRNAs have gradually been recognized as regulators of embryonic development; however, relatively few miRNAs have been identified that regulate cardiac development. A series of recent papers have established an essential role for the miRNA-17-92 (miR-17-92 cluster of miRNAs in the development of the heart. Previous research has shown that the Friend of Gata-2 (FOG-2 is critical for cardiac development. To investigate the possibility that the miR-17-92 cluster regulates FOG-2 expression and inhibits proliferation in mouse embryonic cardiomyocytes we initially used bioinformatics to analyze 3’ untranslated regions (3’UTR of FOG-2 to predict the potential of miR-17-92 to target it. We used luciferase assays to demonstrate that miR-17-5p and miR-20a of miR-17-92 interact with the predicted target sites in the 3’UTR of FOG-2. Furthermore, RT-PCR and Western blot were used to demonstrate the post-transcriptional regulation of FOG-2 by miR-17-92 in embryonic cardiomyocytes from E12.5-day pregnant C57BL/6J mice. Finally, EdU cell assays together with the FOG-2 rescue strategy were employed to evaluate the effect of proliferation on embryonic cardiomyocytes. We first found that the miR-17-5p and miR-20a of miR-17-92 directly target the 3’UTR of FOG-2 and post-transcriptionally repress the expression of FOG-2. Moreover, our findings demonstrated that over-expression of miR-17-92 may inhibit cell proliferation via post-transcriptional repression of FOG-2 in embryonic cardiomyocytes. These results indicate that the miR-17-92 cluster regulates the expression of FOG-2 protein and suggest that the miR-17-92 cluster might play an important role in heart development.

The miR-17-92 cluster regulates FOG-2 expression and inhibits proliferation of mouse embryonic cardiomyocytes.

Science.gov (United States)

Xiang, Rui; Lei, Han; Chen, Mianzhi; Li, Qinwei; Sun, Huan; Ai, Jianzhong; Chen, Tielin; Wang, Honglian; Fang, Yin; Zhou, Qin

2012-02-01

MicroRNAs (miRNAs) have gradually been recognized as regulators of embryonic development; however, relatively few miRNAs have been identified that regulate cardiac development. A series of recent papers have established an essential role for the miRNA-17-92 (miR-17-92) cluster of miRNAs in the development of the heart. Previous research has shown that the Friend of Gata-2 (FOG-2) is critical for cardiac development. To investigate the possibility that the miR-17-92 cluster regulates FOG-2 expression and inhibits proliferation in mouse embryonic cardiomyocytes we initially used bioinformatics to analyze 3' untranslated regions (3'UTR) of FOG-2 to predict the potential of miR-17-92 to target it. We used luciferase assays to demonstrate that miR-17-5p and miR-20a of miR-17-92 interact with the predicted target sites in the 3'UTR of FOG-2. Furthermore, RT-PCR and Western blot were used to demonstrate the post-transcriptional regulation of FOG-2 by miR-17-92 in embryonic cardiomyocytes from E12.5-day pregnant C57BL/6J mice. Finally, EdU cell assays together with the FOG-2 rescue strategy were employed to evaluate the effect of proliferation on embryonic cardiomyocytes. We first found that the miR-17-5p and miR-20a of miR-17-92 directly target the 3'UTR of FOG-2 and post-transcriptionally repress the expression of FOG-2. Moreover, our findings demonstrated that over-expression of miR-17-92 may inhibit cell proliferation via post-transcriptional repression of FOG-2 in embryonic cardiomyocytes. These results indicate that the miR-17-92 cluster regulates the expression of FOG-2 protein and suggest that the miR-17-92 cluster might play an important role in heart development.

Uptake and distribution of nitrogen from acidic fog within a ponderosa pine (Pinus ponderosa Laws.)/litter/soil system

Energy Technology Data Exchange (ETDEWEB)

Fenn, M.E.; Leininger, T.D.

1995-11-01

The magnitude and importance of wet deposition of N in forests of the South Coast (Los Angeles) Air Basin have not been well characterized. We exposed 3-yr-old ponderosa pine (Pinus ponderosa Laws.) seedlings growing in native forest soil to acidic fog treatments (pH 3.1) simulating fog chemistry from a pine forest near Los Angeles, California. Fog solutions contained either {sup 15}NH{sub 4}{sup +}, {sup 15}NO{sub 3}{sup {minus}}, or unlabeled N. The fog treatments were applied in open-top chambers in six 5-hr exposures. Soil treatments within each of the fog exposures were bare soil, soil overlain with L- and F-litter, and soil covered with plastic during the fog events to prevent fogwater from contacting soil. Seedlings were harvested and samples were collected 15 wk after the fog treatments. Uptake of {sup 15}N by roots was by far the dominant pathway for plant assimilation of fog-deposited {sup 15}N. Deposition of N in fog supplied 9.4% and 8.7% of the total N in current-year crown biomass in the litter-overlay and bare-soil treatments, respectively. Total N concentrations in every plant fraction except current-year stems were significantly higher in the bare-soil treatment than in the plastic-covered soil treatment. Less than 5% of the {sup 15}N deposited directly to the seedling crowns was retained by the plants in the covered-soil treatment, whereas 57% of the {sup 15}N deposited to the seedling/litter/soil systems was incorporated into plant biomass. The litter layers retained {sup 15}NH{sub 4}{sup +} more effectively than {sup 15}NH{sub 4}{sup +} more effectively than {sup 15}NO{sub 3}. Data from this study suggest that N deposited from fog may be an important source of N for plant growth in forests of the SCAB where fog occurrence and pollution exposure coincide. 5 refs., 5 figs., 3 tabs.

The potential for scaling up a fog collection system on the eastern escarpment of Eritrea

OpenAIRE

Fessehaye, Mussie; Abdul-Wahab, Sabah A.; Savage, Michael J.; Kohler, Thomas; Tesfay, Selamawit

2015-01-01

Fog is an untapped natural resource. A number of studies have been undertaken to understand its potential as an alternative or complementary water source. In 2007, a pilot fog-collection project was implemented in 2 villages on the Eastern Escarpment of Eritrea. The government of Eritrea, buoyed by the project’s positive results, has encouraged research into and application of fog-collection technologies to alleviate water-supply problems in this region. In 2014, this study was undertaken to ...

The Effect of Lifting Speed on Cumulative and Peak Biomechanical Loading for Symmetric Lifting Tasks

Directory of Open Access Journals (Sweden)

Kasey O. Greenland

2013-06-01

Conclusion: Based on peak values, BCF is highest for fast speeds, but the BCF cumulative loading is highest for slow speeds, with the largest difference between fast and slow lifts. This may imply that a slow lifting speed is at least as hazardous as a fast lifting speed. It is important to consider the duration of lift when determining risks for back and shoulder injuries due to lifting and that peak values alone are likely not sufficient.

Scaling of lifting forces in relation to object size in whole body lifting

NARCIS (Netherlands)

Kingma, I.; van Dieen, J.H.; Toussaint, H.M.

2005-01-01

Subjects prepare for a whole body lifting movement by adjusting their posture and scaling their lifting forces to the expected object weight. The expectancy is based on visual and haptic size cues. This study aimed to find out whether lifting force overshoots related to object size cues disappear or

Study of lifting operation of a tripod foundation for offshore wind turbine

Science.gov (United States)

Zhu, H.; Li, L.; Ong, M. C.

2017-12-01

This study addresses numerical analysis of the installation of a tripod foundation using a heavy lift vessel (HLV). Limiting sea states are firstly predicted in the frequency domain based on crane tip vertical motions using linear transfer functions. Then, numerical modelling and simulations are carried out in the time domain to analyse the coupled dynamic system taking into consideration of the nonlinearities of the system. In time-domain analysis, two lifting phases are brought into focus, i.e., the lift-off and the lowering phases. For the lift-off phase, two scenarios are considered, i.e., lift-off from the own deck of the HLV and lift-off from a transport barge. Moreover, comparative studies using two types of installation vessels, a floating vessel and a Jack-up, are investigated for the lowering process. Critical responses including the motions of the tripod and the lift wire tensions are presented and compared under various environmental and loading conditions.

Fog Chemistry at Different Altitudes in the Swiss Alps

Science.gov (United States)

Michna, P.; Eugster, W.; Wanner, H.

2010-07-01

During two extended summer seasons in 2006 and 2007, we installed two battery driven versions of the Caltech active strand cloud water collector (MiniCASCC) at the Niesen mountain in the northern Swiss Alps. Along, we measured air temperature, relative humidity, wind, and visibility. During these two field operation phases we gained weekly samples of fogwater, where we analysed the major anions and cations, and the stable water isotopes δD and δ18O. The fog collectors were installed at an altitude of 2300 and 1600 m asl to resolve altitudinal differences in fog chemistry. We found a large variability between the events, but no clear altitudinal gradient. At both sites, the most important ions were nitrate, ammonium, and sulphate. Higher concentrations occured preferably in late spring (start of sampling period) and in autumn (end of sampling). Compared to previous studies at lower elevations in the Swiss Plateau during wintertime, our measurements showed considerable lower ion loads in the fogwater. The combination of these results suggest that lowest ion loads are found in convective clouds with a short lifetime and that the highest ion loads occur during radiation fog events at lower elevations.

Chemical characterization of fog and rain water collected at the eastern Andes cordillera

Directory of Open Access Journals (Sweden)

E. Beiderwieden

2005-01-01

Full Text Available During a three month period in 2003 and 2004, the chemistry of fog and rainwater were studied at the 'El Tiro' site in a tropical mountain forest ecosystem in Ecuador, South America. The fogwater samples were collected using a passive fog collector, and for the rain water, a standard rain sampler was employed. For all samples, electric conductivity, pH, and the concentrations of NH4+, K+, Na+, Ca2+, Mg2+, Cl−, NO3−, PO43−, and SO42− were measured. For each fog sample, a 5 day back trajectory was calculated by the use of the HYSPLIT model. Two types of trajectories occurred. One type was characterized by advection of air masses from the East over the Amazonian basin, the other trajectory arrived one from the West after significant travel time over the Pacific Ocean. We found considerably higher ion concentrations in fogwater samples than in rain samples. Median pH values are 4.58 for fog water, and 5.26 for the rain samples, respectively. The median electric conductivity was 23 μS cm−1 for the fog and 6 μS cm−1 for the rain. The continent samples exhibit higher concentrations of most ions as compared to the pacific samples, but these differences could not be detected statistically.

Internal acid buffering in San Joaquin Valley fog drops and its influence on aerosol processing

Science.gov (United States)

Collett, Jeffrey L.; Hoag, Katherine J.; Rao, Xin; Pandis, Spyros N.

Although several chemical pathways exist for S(IV) oxidation in fogs and clouds, many are self-limiting: as sulfuric acid is produced and the drop pH declines, the rates of these pathways also decline. Some of the acid that is produced can be buffered by uptake of gaseous ammonia. Additional internal buffering can result from protonation of weak and strong bases present in solution. Acid titrations of high pH fog samples (median pH=6.49) collected in California's San Joaquin Valley reveal the presence of considerable internal acid buffering. In samples collected at a rural location, the observed internal buffering could be nearly accounted for based on concentrations of ammonia and bicarbonate present in solution. In samples collected in the cities of Fresno and Bakersfield, however, significant additional, unexplained buffering was present over a pH range extending from approximately four to seven. The additional buffering was found to be associated with dissolved compounds in the fogwater. It could not be accounted for by measured concentrations of low molecular weight ( C1- C3) carboxylic acids, S(IV), phosphate, or nitrophenols. The amount of unexplained buffering in individual fog samples was found to correlate strongly with the sum of sample acetate and formate concentrations, suggesting that unmeasured organic species may be important contributors. Simulation of a Bakersfield fog episode with and without the additional, unexplained buffering revealed a significant impact on the fog chemistry. When the additional buffering was included, the simulated fog pH remained 0.3-0.7 pH units higher and the amount of sulfate present after the fog evaporated was increased by 50%. Including the additional buffering in the model simulation did not affect fogwater nitrate concentrations and was found to slightly decrease ammonium concentrations. The magnitude of the buffering effect on aqueous sulfate production is sensitive to the amount of ozone present to oxidize S

The design of an optimal fog water collector: A theoretical analysis

Science.gov (United States)

Regalado, Carlos M.; Ritter, Axel

2016-09-01

We investigate the collection efficiency of different fog water catchers assemblies (mainly flat and cylindrical structures equipped with several screens of staggered filaments) by means of parametric equations which take into consideration both impaction and aerodynamic effects. We introduce different models that vary in complexity and range of applicability, and may be used to analyze the effect that geometry, number of screens, spacing and inclination of the filament strands have on the fog water yield of the collector. Increasing the number of impacting screens, nR, is shown to improve the collection efficiency up to an optimum for nR = 3-5; beyond nR > 5 impermeability to the airflow makes the fog catcher less efficient. Geometry of the collector is shown to be relatively important: unless wind direction varies widely, the rectangular flat design is preferred over the cylindrical one, because of its larger drag, i.e. increased aerodynamic efficiency, ηa. In fact ηa is shown to be limiting, such that values over ηa > 50% are difficult to attain. By contrast the impaction efficiency, ηimp, of fog water droplets onto multiple nR parallel screens of filaments may reach theoretical values of ηimp > 80%. Inclination of the impacting screens over the vertical may slightly reduce ηimp, but this may be compensated by a reduction in flow resistance, i.e. increased aerodynamic efficiency.

Proactive vs reactive failure recovery assessment in combined fog-to-cloud (F2C) systems

OpenAIRE

Souza, Vitor Barbosa Carlos de; Masip Bruin, Xavier; Marín Tordera, Eva; Ramirez Almonte, Wilson; Sánchez López, Sergio

2017-01-01

The increasing number of end user devices at the edge of the network, along with their ever increasing computing capacity, as well as the advances in Data Center technologies, paved the way for the generation of Internet of Things (IoT). Several IoT services have been deployed leveraging Cloud Computing and, more recently, Fog Computing. In order to enable efficient control of cloud and fog premises, Fog-to-Cloud (F2C) has been recently proposed as a distributed architecture for coordinated m...

Fog in a marginal agricultural area surrounded by montane Andean cloud forest during El Niño climate

Science.gov (United States)

García-Santos, G.

2010-07-01

The aim of the present study was to evaluate temporal variations of water inputs, rainfall and fog (cloud water), and its contribution to the water balance in a marginal agricultural area of potato surrounded by tropical montane cloud forest in Colombia. Fog in the air boundary layer was estimated using a cylindrical fog collector. Liquid water content of fog events were evaluated before and during natural climate event of El Niño. Our study shows the temporal variation of these two water inputs in both daily and monthly cycles on Boyacá at 2900 m a.s.l. Rainfall was the most frequently observed atmospheric phenomenon, being present on average 62% of the days per year, whereas fog was 45% of the time. Reflected on the lower frequency, annual amount of fog was 11% of precipitation. However during the anomalous dry climate of El Niño, total amount of rainfall was negligible and the few fog events were the only water source for plant growth. Estimated water crop requirements were higher than the water inputs. The survival of the crops was explained by meteorological conditions during dew and fog events. High relative humidity might have eased the plant’s water stress by decreasing transpiration and temperature in leaves and soil, affecting the water balance and the heat exchange between the atmosphere-land interfaces in the marginal agricultural areas during exceptional dry climate.

Modeling and Design of Hybrid PEM Fuel Cell Systems for Lift Trucks

DEFF Research Database (Denmark)

Hosseinzadeh, Elham

driven lift trucks are being used more and more in different companies to reduce their emissions. However, battery driven lift trucks need a long time to recharge and thus may be out of work for a long time. Fuel cell driven lift trucks diminish this problem and are therefore getting more attention...... in a fork-lift truck. In order for the ejector to operate in the largest possible range of load, different approaches (with fixed nozzle and variable nozzle ejectors) have been investigated. Different geometries have been studied in order to optimize the ejector. The optimization is carried out not only...... a virtual fork-lift system. This investigation examines important performance metrics, such as hydrogen consumption and battery SOC as a function of the fuel cell and battery size, control strategy, drive cycle, and load variation for a fork-lift truck system. This study can be used as a benchmark...

Gene response in rice plants treated with continuous fog influenced by pH, was similar to that treated with biotic stress.

Science.gov (United States)

Satoh, Kouji; Saji, Shoko; Ito, Shoko; Shimizu, Hideyuki; Saji, Hikaru; Kikuchi, Shoshi

2014-01-01

Throughout Asia, including Japan, rice plants are cultivated in a wide range of areas from lowlands to highlands and are frequently exposed to fog, including acid fog. Some physiological studies have shown that acid fog can be a stress factor for plants. We analyzed the gene expression profiles of rice plants treated with artificially prepared simulated acid fog (SiAF) or simulated neutral fog (SiNF) for 1 or 7 days. Microarray analysis results suggested that both the SiAF and the SiNF treatments induced the expression of genes involved in the defense and stress responses in rice plants. Induction of such genes was detected in plants treated with SiAF for 1 day, and the number of induced genes increased in plants treated with SiAF for 7 days. The genes for defense and stress responses were also induced by SiNF for 7 days, although they were not induced by SiNF for 1 day. The gene expression profiles of the SiAF-treated and the SiNF-treated plants were compared to those of plants treated with other stress factors. The comparison revealed that both SiAF and SiNF treatments have similar effects to biotic stresses and ozone stress. The genes encoding NADPH oxidase and germin, which function in apoplasts, were also induced by SiAF, SiNF and biotic stresses. These findings suggest that both the SiAF and the SiNF treatments may result in oxidative stress through the apoplastic production of reactive oxygen species.

The chemical composition of fogs and clouds in Southern California

Energy Technology Data Exchange (ETDEWEB)

Munger, J.W.

1989-01-01

The major inorganic species in cloud and fog water samples were NH{sub 4}{sup +}, H{sup +}, NO{sub 3}{sup {minus}}, and SO{sub 4}{sup 2{minus}}. Concentrations in fog water samples were 1 - 10 {times} 10{sup {minus}3} M; pH values ranged from {approx equal} 2 to 6. Nitrate usually exceeded sulfate. Acidity depended on the availability of NH{sub 3} from agricultural operations. Stratus cloudwater had somewhat lower concentrations; pH values were in the range 3-4. The major factors accounting for variation in fog- or cloudwater composition were the preexisting aerosol and gas concentrations and variations in liquid water content. Deposition and entrainment or advection of different air masses were also important during extended cloud or fog episodes. The droplet size dependence of cloudwater composition was investigated on one occasion in an intercepted coastal stratus clouds. Concentrations of S(IV) and CH{sub 2}O in the range 100-1000 {mu}M were observed in fogwater from urban sites in Southern California. Lower concentrations were observed in stratus clouds. The high levels of S(IV) and CH{sub 2}O were attributed to the formation of hydroxymethanesulfonate (HMSA), the S(IV) adduct of CH{sub 2}O. Direct measurements of HMSA in fogwater samples from Bakersfield, CA were made by ion-pairing chromatography. Glyoxal and methyglyoxal were observed at concentrations comparable to CH{sub 2}O in fogwater samples from Riverside, CA and in stratus cloudwater samples from sites along the Santa Barbara Channel.

Temporal Variability and Characterization of Aerosols across the Pakistan Region during the Winter Fog Periods

Directory of Open Access Journals (Sweden)

Muhammad Fahim Khokhar

2016-05-01

Full Text Available Fog is a meteorological/environmental phenomenon which happens across the Indo-Gangetic Plains (IGP and leads to significant social and economic problems, especially posing significant threats to public health and causing disruptions in air and road traffic. Meteorological stations in Pakistan provide limited information regarding fog episodes as these provide only point observations. Continuous monitoring, as well as a spatially coherent picture of fog distribution, is possible through the use of satellite observations. This study focuses on the 2012–2015 winter fog episodes over the Pakistan region using the Moderate Resolution Image Spectrometer (MODIS, the Ozone Monitoring Instrument and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO products. The main objective of the study was to map the spatial distribution of aerosols, their types, and to identify the aerosol origins during special weather conditions like fog in Pakistan. The study also included ground monitoring of particulate matter (PM concentrations, which were conducted during the 2014–2015 winter period only. Overall, this study is part of a multi-country project supported by the International Centre for Integrated Mountain Development (ICIMOD, started in 2014–2015 winter period, whereby scientists from Bangladesh, India and Nepal have also conducted measurements at their respective sites. A significant correlation between MODIS (AOD and AERONET Station (AOD data from Lahore was identified. Mass concentration of PM10 at all sampling sites within Lahore city exceeded the National Environmental Quality Standards (NEQS levels on most of the occasions. Smoke and absorbing aerosol were found to be major constituents of winter fog in Pakistan. Furthermore, an extended span of winter fog was also observed in Lahore city during the winter of 2014–2015. The Vertical Feature Mask (VFM provided by CALIPSO satellite confirmed the low-lying aerosol

Coastal California's Fog Aerobiology and Ecology: Designing and Testing an Optimal Passive Impactor Collection Unit

Science.gov (United States)

Gentry, D.; Whinnery, J. T.; Ly, V. T.; Travers, S. V.; Sagaga, J.; Dahlgren, R. P.

2017-12-01

Microorganisms play a major role in our biosphere due to their ability to alter water, carbon and other geochemical cycles. Fog and low-level cloud water can play a major role in dispersing and supporting such microbial diversity. An ideal region to gather these microorganisms for characterization is the central coast of California, where dense fog is common. Fog captured from an unmanned aerial vehicle (UAV) at different altitudes will be analyzed to better understand the nature of microorganisms in the lower atmosphere and their potential geochemical impacts. The capture design consists of a square-meter hydrophobic mesh that hangs from a carbon fiber rod attached to a UAV. The DJI M600, a hexacopter, will be utilized as the transport for the payload, the passive impactor collection unit (PICU). The M600 will hover in a fog bank at altitudes between 10 and 100 m collecting water samples via the PICU. A computational flow dynamics (CFD) model will optimize the PICU's size, shape and placement for maximum capture efficiency and to avoid contamination from the UAV downwash. On board, there will also be an altitude, temperature and barometric pressure sensor whose output is logged to an SD card. A scale model of the PICU has been tested with several different types of hydrophobic meshes in a fog chamber at 90-95% humidity; polypropylene was found to capture the fog droplets most efficiently at a rate of .0042 g/cm2/hour. If the amount collected is proportional to the area of mesh, the estimated amount of water collected under optimal fog and flight conditions by the impactor is 21.3 g. If successful, this work will help identify the organisms living in the lower atmosphere as well as their potential geochemical impacts.

PM10 Sampling and AOD Trends during 2016 Winter Fog Season in the Islamabad Region

KAUST Repository

Bulbul, Gufran; Shahid, Imran; Chishtie, Farrukh; Shahid, Muhammad Zeeshaan; Hundal, Rabia Ali; Zahra, Fatima; Shahzad, Muhammad Imran

2017-01-01

PM samples were collected during intensive fog days in Islamabad, Pakistan, to investigate the impact of particulate matter on fog formation. The PM concentrations were monitored at the Institute of Space Technology site using a high-volume air

Humidification - Fogging and other evaporative cooling in greenhouses

NARCIS (Netherlands)

Nederhoff, E.M.; Weel, van P.A.

2011-01-01

Fogging, misting, roof sprinklers, pad-and-fan and other techniques based on water evaporation are effective tools for improving the growing conditions in a greenhouse when humidity is low. They should be used wisely though.

New heavy-lift system under construction

Energy Technology Data Exchange (ETDEWEB)

2009-07-01

Heavy-lift availability is at a premium, and the market is eager for alternatives to meet the demand. An alternative heavy-lift solution from SeaMetric - which has two multi-purpose heavy-lift vessels under construction in China - will be available in the first quarter of 2011. The TML system is based on buoyancy and ballast tanks, with four lifting arms mounted on two identical vessels, each vessel measuring 140 x 40 x 10.75 metres. To perform a lift, one TML with lifting arms is positioned on each side of the object. Using seawater pumps, lift force is created by de ballasting the buoyancy tanks and at the same time ballasting the ballast tanks. (AG). tab., ills

Analysis of prospective systems for fog warnings.

Science.gov (United States)

2013-07-01

On November 22, 2012, at about 8:35 a.m., thick fog resulted in a 140 vehicle accident near Beaumont, : Texas. Remarkably, only two people died and 80 people were injured and required hospital care. On : January 29, 2012, about 4:00 a.m., amidst thic...

Lift, drag, and guidance forces on alternating polarity magnets, using loop guideways

International Nuclear Information System (INIS)

Lindenbaum, S.D.; Lee, M.S.

1975-01-01

Exact solutions of track current, lift force, and drag force, together with their velocity dependence, have been computed for a vehicle carrying a finite number of fixed current alternating polarity superconducting magnets, suspended at various heights over structured track guideways of the single- and double-loop (''null'') types. Results for the double-loop case are compared with those of a previously reported approximate analysis. The analytical method is then applied to a study of a low-drag guidance loop guideway which is integrable with lift loop guideways utilizing a common set of vehicle magnets. Solutions are obtained for guidance track restoring forces, lateral destabilization forces, and lift force degradation as functions of lateral displacement from symmetry. The dependence of lift, drag, and lift-to-drag on track loop parameters is studied and the linear dependence of lift-to-drag on loop time constant confirmed. The contribution to the forces made by successive addition of alternating polarity magnets is calculated and the marked reduction in lift force pulsation noted

Severe haze episodes and seriously polluted fog water in Ji'nan, China.

Science.gov (United States)

Wang, Xinfeng; Chen, Jianmin; Sun, Jianfeng; Li, Weijun; Yang, Lingxiao; Wen, Liang; Wang, Wenxing; Wang, Xinming; Collett, Jeffrey L; Shi, Yang; Zhang, Qingzhu; Hu, Jingtian; Yao, Lan; Zhu, Yanhong; Sui, Xiao; Sun, Xiaomin; Mellouki, Abdelwahid

2014-09-15

Haze episodes often hit urban cities in China recently. Here, we present several continuous haze episodes with extremely high PM2.5 levels that occurred over several weeks in early 2013 and extended across most parts of the northern and eastern China-far exceeding the Beijing-Tianjin-Hebei region. Particularly, the haze episode covered ~1 million km(2) on January 14, 2013 and the daily averaged PM2.5 concentration exceeded 360 μg m(-3) in Ji'nan. The observed maximum hourly PM2.5 concentration in urban Ji'nan reached 701 μg m(-3) at 7:00 am (local time) in January 30. During these haze episodes, several fog events happened and the concurrent fog water was found to be seriously polluted. For the fog water collected in Ji'nan from 10:00 pm in January 14 to 11:00 am in January 15, sulfate, nitrate, and ammonium were the major ions with concentrations of 1.54 × 10(6), 8.98 × 10(5), and 1.75 × 10(6) μeq L(-1), respectively, leading to a low in-situ pH of 3.30. The sulfate content in the fog sample was more than 544 times as high as those observed in other areas. With examination of the simultaneously observed data on PM2.5 and its chemical composition, the fog played a role in scavenging and removing fine particles from the atmosphere during haze episodes and thus was seriously contaminated. However, the effect was not sufficient to obviously cleanse air pollution and block haze episodes. Copyright © 2014 Elsevier B.V. All rights reserved.

CFD Study of a New Annular Lift Fan Configuration with High Lift Efficiency

Directory of Open Access Journals (Sweden)

Yun Jiang

2017-03-01

Full Text Available A new annular lift fan configuration that has very high lift efficiency is explored by using a numerical scheme. The inlet lip radius and diffuser angle are maximized by semicircle duct walls and the location of the lift fan is moved from the throat to the diffuser area to maximize the diffusion effect of the ducted fan. The improved lift fan achieves the figure of merit of 0.772 and the power loading of 9.03 lbs/hp without ground effect, very close to the theoretical limit. Under the ground effect, the figure of merit reaches 0.822 with the power loading of 9.62 lbs/hp. The improved lift efficiency deteriorates the transition characteristics with higher momentum drag and pitching moment. However, with the aid of jet thrusts directly providing part of the lift during transition, the peak of momentum drag and pitching moment can be lowered. A total thrust to weight ratio of 0.7 is enough for all of the requirements in transition and in hover and for the maximum speed of 0.75 Mach in cruise flight.

EFFECTS OF FOG PRECIPITATION ON WATER RESOURCES AND DRINKING WATER TREATMENT IN THE JIZERA MOUNTAINS, THE CZECH REPUBLIC

Directory of Open Access Journals (Sweden)

Josef Křeček

2015-07-01

Full Text Available Water yield from catchments with a high evidence of fog or low clouds could be increased by the canopy fog drip. However, in areas with the acid atmospheric deposition, this process can lead to the decline of water quality. The aim of this study is to analyze fog related processes in headwater catchments of the Jizera Mountains (the Czech Republic with special attention to water quality and the drinking water treatment. In two years (2011-2012, the fog drip was observed by twelve passive fog collectors at transect of the Jizerka experimental catchment. Methods of space interpolation and extrapolation (ArcGis 10.2 were applied to approximate the areal atmospheric deposition of fog water, sulphur and nitrogen, in catchments of the drinking water reservoirs Josefův Důl and Souš. The mean annual fog drip from vegetation canopy was found between 88 and 106 mm (i.e. 7 to 9 percent of precipitation, and 11 to 13 percent of water yield, estimated by standard rain gauge monitoring. But, the mean annual load of sulphur and nitrogen by the fog drip was 1,975 and 1,080, kilograms per square kilometre, respectively (i.e. 55 and 48 percent of total deposition of sulphur and nitrogen, registered in the bulk. The acidification of surface waters leads to rising operational costs in the water treatment plants (liming, reduce of heavy metals, more frequent control of sand filters etc.. In a catchment scale, the additional precipitation, caused by the canopy fog drip, could be controlled by the effective watershed management (support of forests stands near the native composition with presence of deciduous trees: beech, mountain ash, or birch.

FOG Random Drift Signal Denoising Based on the Improved AR Model and Modified Sage-Husa Adaptive Kalman Filter.

Science.gov (United States)

Sun, Jin; Xu, Xiaosu; Liu, Yiting; Zhang, Tao; Li, Yao

2016-07-12

In order to reduce the influence of fiber optic gyroscope (FOG) random drift error on inertial navigation systems, an improved auto regressive (AR) model is put forward in this paper. First, based on real-time observations at each restart of the gyroscope, the model of FOG random drift can be established online. In the improved AR model, the FOG measured signal is employed instead of the zero mean signals. Then, the modified Sage-Husa adaptive Kalman filter (SHAKF) is introduced, which can directly carry out real-time filtering on the FOG signals. Finally, static and dynamic experiments are done to verify the effectiveness. The filtering results are analyzed with Allan variance. The analysis results show that the improved AR model has high fitting accuracy and strong adaptability, and the minimum fitting accuracy of single noise is 93.2%. Based on the improved AR(3) model, the denoising method of SHAKF is more effective than traditional methods, and its effect is better than 30%. The random drift error of FOG is reduced effectively, and the precision of the FOG is improved.

Trapping fresh sea breeze in desert? Health status of Camanchaca, Atacama's fog.

Science.gov (United States)

Bonnail, Estefanía; Cunha Lima, Ricardo; Martínez Turrieta, Gladys

2018-05-24

Water fog composition was investigated at a fog harvesting installation in the coast of Atacama (North Chile). Chañaral is historically affected by mining contamination discharges. Hydro-chemical characterization of fog water from top of the mountain (where capture installation is located) and at the bottom of the mountain (after vertical transportation where an aquaponic system is located) revealed many compositional differences that compromise the use of water. High acidity and high concentrations in Cu and As in water collected on top of the mountain were found; meanwhile, acidity and Cu decreased, and As levels overpassed the drinking water standards after the vertical transportation. Collected data was assessed according to national and international regulatory standards, neutralization factors (NF), sodium adsorption ratio (SAR), and ion ratios to determine origin of contamination and suitability of destined for human consumption, irrigation, or aquaculture purposes.

Clean fog rapid procedure test of artificially and naturally polluted HVDC porcelain barrel insulators

International Nuclear Information System (INIS)

Vlastos, A.E.

1992-01-01

The first question asked in this paper refers to the variation of the peak leakage current prior to the flashover and the variation of the time prior to flashover in the test of artificially polluted insulators when using the up-and-down method. To answer this question sums up the test procedure used in the up-and-down method. For each trial represented the insulator was again polluted artificially and then dried following the procedure described in the paper. Then the insulator was transported into the fog chamber and the voltage and fog was switched on simultaneously. In these experiments a low fog injection rate was used

Investigation of fog structure affected by gravity waves and turbulence in the mountainous region of Pyeongchang, Korea, the place for the 2018 Winter Olympics and Paralympics

Science.gov (United States)

La, I.; Yum, S. S.; Yeom, J. M.; Gultepe, I.

2017-12-01

Since microphysical and dynamical processes of fog are not well-known and have non-linear relationships among processes that are related to fog formation, improving the accuracy of the fog forecasting/nowcasting system is challenging. For these reasons, understanding the fog mechanism is needed to develop the fog forecasting system. So, we focus on understanding fog-turbulence interactions and fog-gravity wave interactions. Many studies noted that turbulence plays important roles in fog. However, a discrepancy between arguments for the effect of turbulent mixing on fog formation exists. Several studies suggested that turbulent mixing suppresses fog formation. Some other studies reported that turbulent mixing contributes to fog formation. On the other hand, several quasi-periodic oscillations of temperature, visibility, and vertical velocity, which have period of 10-20 minutes, were observed to be related to gravity waves in fog; because gravity waves play significant dynamic roles in the atmosphere. Furthermore, a numerical study suggested that gravity waves, simulated near the top of the fog layer, may affect fog microphysics. Thus, we investigate the effects of turbulent mixing on fog formation and the influences of gravity waves on fog microphysics to understand fog structure in Pyeongchang. In these studies, we analyze the data that are obtained from doppler lidar and 3.5 m meteorological observation tower including 3D-ultrasonic anemometer, IR sensor, and fog monitor during ICE-POP (International Collaborative Experiments for Pyeongchang 2018 Olympic and Paralympic winter games) campaign. In these instruments, doppler lidar is a good instrument to observe the gravity waves near the fog top, while in situ measurements have small spatial coverage. The instruments are installed at the mountainous terrain of Pyeongchang, Korea. More details will be presented at the conference.

Semivolatile Organic Compounds (SOCs) in Fine Particulate Matter (PM2.5) during Clear, Fog, and Haze Episodes in Winter in Beijing, China.

Science.gov (United States)

Wang, Ting; Tian, Mi; Ding, Nan; Yan, Xiao; Chen, She-Jun; Mo, Yang-Zhi; Yang, Wei-Qiang; Bi, Xin-Hui; Wang, Xin-Ming; Mai, Bi-Xian

2018-05-01

Few efforts have been made to elucidate the influence of weather conditions on the fate of semivolatile organic compounds (SOCs). Here, daily fine particulate matter (PM 2.5 ) during clear, haze, and fog episodes collected in the winter in Beijing, China was analyzed for polycyclic aromatic hydrocarbons (PAHs), brominated flame retardants (BFRs), and organophosphate flame retardants (OPFRs). The total concentrations of PAHs, OPFRs, and BFRs had medians of 45.1 ng/m 3 and 1347 and 46.7 pg/m 3 , respectively. The temporal pattern for PAH concentrations was largely dependent on coal combustion for residential heating. OPFR compositions that change during colder period were related to enhanced indoor emissions due to heating. The mean concentrations of SOCs during haze and fog days were 2-10 times higher than those during clear days. We found that BFRs with lower octanol and air partition coefficients tended to increase during haze and fog episodes, be removed from PM 2.5 during clear episodes, or both. For PAHs and OPFRs, pollutants that are more recalcitrant to degradation were prone to accumulate during haze and fog days. The potential source contribution function (PSCF) model indicated that southern and eastern cities were major source regions of SOCs at this site.

Laser-induced forward transfer (LIFT) of congruent voxels

Science.gov (United States)

Piqué, Alberto; Kim, Heungsoo; Auyeung, Raymond C. Y.; Beniam, Iyoel; Breckenfeld, Eric

2016-06-01

Laser-induced forward transfer (LIFT) of functional materials offers unique advantages and capabilities for the rapid prototyping of electronic, optical and sensor elements. The use of LIFT for printing high viscosity metallic nano-inks and nano-pastes can be optimized for the transfer of voxels congruent with the shape of the laser pulse, forming thin film-like structures non-lithographically. These processes are capable of printing patterns with excellent lateral resolution and thickness uniformity typically found in 3-dimensional stacked assemblies, MEMS-like structures and free-standing interconnects. However, in order to achieve congruent voxel transfer with LIFT, the particle size and viscosity of the ink or paste suspensions must be adjusted to minimize variations due to wetting and drying effects. When LIFT is carried out with high-viscosity nano-suspensions, the printed voxel size and shape become controllable parameters, allowing the printing of thin-film like structures whose shape is determined by the spatial distribution of the laser pulse. The result is a new level of parallelization beyond current serial direct-write processes whereby the geometry of each printed voxel can be optimized according to the pattern design. This work shows how LIFT of congruent voxels can be applied to the fabrication of 2D and 3D microstructures by adjusting the viscosity of the nano-suspension and laser transfer parameters.

Effect of basic fog of medical x-ray films on image quality and patient dose-method of evaluation and steps to control

International Nuclear Information System (INIS)

Bohra, Reena; Nair, C.P.R.; Jayalakshmi, V.; Govindarajan, K.N.; Bhatt, B.C.

2003-01-01

Unacceptable basic fog of medical x-ray films has been reported recently from many hospitals. The paper presents the effect of basic fog on radiographic quality of films like sensitivity (speed), contrast and maximum density (DMax). Several batches of general- purpose medical x-ray films from five different manufacturers were studied to evaluate batch-to-batch variation in basic fog. Increase in basic fog with aging of films was also evaluated. Reasons for increased basic fog observed in the film processing facilities of a few hospitals were analysed. Factors responsible for increase in basic fog and the steps to control it have been discussed

Measurement of fog and cloud water constituents - results of the Stuttgart-Hohenheim campaign

International Nuclear Information System (INIS)

Lammel, G.; Metzig, G.; Ziereis, H.; Klumpp, J.

1993-01-01

A radiation fog event in a highly polluted environment was characterized physically and chemically. Various sampling techniques, including size resolved, and an almost complete set of chemical-analytical methods were applied. Methods for conservation and sensitive determination of reduced nitrogen and sulfur compounds in the liquid phase are presented for the first time. Besides other pollutants, the air mass was heavily loaded by carbonaceous material (carbon accounted for more than one third of the particulate mass). The most prominent trace species in the fog droplets were sulfate, nitrate and ammonium ions. Concentrations as high as 130 mg/I and 50 mg/I, each, were achieved prior to dissolution of the fog in the small and large droplet fraction, respectively. The acidity was negligible, however. The fraction of reduced sulfur compounds was 7% by average, up to 79%, however, at the onset of the fog event. As found in the context of earlier field campaigns, large droplets were less pollutant loaded than small droplets. Besides gas scavenging and - in the case of SO 2 - succeeding oxidation, the scavenging of particulate matter night have contributed to the liquid phase chemical composition. (orig.) [de

Intercomparison of fog water samplers

OpenAIRE

SCHELL, DIETER; GEORGII, HANS-WALTER; MASER, ROLF; JAESCHKE, WOLFGANG; ARENDS, BEATE G.; KOS, GERARD P. A.; WINKLER, PETER; SCHNEIDER, THOMAS; BERNER, AXEL; KRUISZ, CHRISTIAN

2011-01-01

During the Po Valley Fog Experiment 1989, 2 fogwater collectors were operated simultaneously at the ground and the results were compared to each other. The chemical analyses of the samples as well as the collection efficiencies showed remarkable differences between both collectors. Some differences in the solute concentrations in the samples of both collectors could be expected due to small differences in the 50% cut-off diameters (5 < d50 < 7 µm). The large differences in the collectio...

On the removal efficiency of padon decay products by fog droplets

International Nuclear Information System (INIS)

Girgzhdis, A.I.; Girgzhdene, R.V.; Shopauskas, K.K.

1978-01-01

The results of the experimental investigations on quantitative evaluation of the 218 Po and 214 Bi washout efficiency by fog in an aerosol chamber are presented. The radioactivity has been measured by means of α-spectrometric method. Comparison of eXperimental and calculated data is made. The 218 Po and 214 Bi washout efficiency ratio is found to be dependent mainly on the aerosol concentration. The change of 218 Po concentration imitates the process of coagulation of free atoms of light ions, and that of 214 Bi - of aerosol particles by fog droplets

How Do Wings Generate Lift?

Indian Academy of Sciences (India)

ideas to get expressions for lift and moment that are remarkably accurate. The pressure ... ating a lift force, leads to a nose-up or nose-down moment also. .... venient to use for a fluid since we would like to deal with a flow .... energy to get lift?

Revisiting Fog as an Important Constituent of the Atmosphere

Czech Academy of Sciences Publication Activity Database

Hůnová, I.; Brabec, Marek; Malý, Marek; Valeriánová, A.

2018-01-01

Roč. 636, September 2018 (2018), s. 1490-1499 ISSN 0048-9697 Institutional support: RVO:67985807 Keywords : Fog * Generalized additive model * Meteorology * Air pollution Impact factor: 4.900, year: 2016

Fogging Control on LDPE/EVA Coextruded Films: Wettability Behavior and Its Correlation with Electric Performance

Directory of Open Access Journals (Sweden)

Miguel A. Waldo-Mendoza

2017-02-01

Full Text Available The transformation of fog at a non-visible water layer on a membrane of low-density polyethylene (LDPE and ethylene-vinyl acetate (EVA was evaluated. Nonionic surfactants of major demand in the polyolefin industry were studied. A kinetic study using a hot fog chamber showed that condensation is controlled by both the diffusion and permanency of the surfactant more than by the change of the surface energy developed by the wetting agents. The greatest permanency of the anti-fog effect of the LDPE/EVA surface was close to 3000 h. The contact angle results demonstrated the ability of the wetting agent to spread out to the surface. Complementarily, the migration of nonionic surfactants from the inside of the polymeric matrix to the surface was analyzed by Fourier transform infrared (FTIR microscopy. Additionally, electrical measurement on the anti-fogging membrane at alternating currents and at a sweep frequency was proposed to test the conductivity and wetting ability of nonionic surfactants. We proved that the amphiphilic molecules had the ability to increase the conductivity in the polyolefin membrane. A correlation between the bulk electrical conductivity and the permanency of the fogging control on the LDPE/EVA coextruded film was found.

Pollutant Concentrations in the Rime and Fog Water at the Milesovka Observatory

Czech Academy of Sciences Publication Activity Database

Fišák, Jaroslav; Tesař, Miroslav; Fottová, D.

2009-01-01

Roč. 196, 1-4 (2009), s. 273-285 ISSN 0049-6979 R&D Projects: GA AV ČR IAA3042301; GA AV ČR 1QS200420562 Institutional research plan: CEZ:AV0Z30420517; CEZ:AV0Z20600510 Keywords : Deposited precipitation * Fog collection * Fog water * Milesovka observatory * Rime water Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.676, year: 2009 http://springerlink.metapress.com/content/18q3lr7681736qp2/fulltext.pdf

Warm and Humid Air Blowing over Cold Water - Grand Banks Fog

Science.gov (United States)

Taylor, P.; Weng, W.

2016-12-01

The condensation of water vapour into droplets and the formation of fog in the Earth's atmospheric boundary layer involves a complex balance between horizontal advection and vertical turbulent mixing of heat and water vapour, cloud microphysical processes and radiative transfers of heat, plus the impact of water droplets, and sometimes ice crystals, on visibility. It is a phenomenon which has been studied for many years in a variety of contexts. On land, surface cooling of the ground via long wave radiation at night is often the trigger and a number of 1-D (height and time dependent) radiative fog models have been developed. Over the waters offshore from Newfoundland a key factor is the advection of moist air from over warm gulf stream waters to colder Labrador current water - an internal boundary-layer problem. Some basic properties can be learned from a steady state 2-D (x-z) model.The WTS (Weng, Taylor and Salmon, 2010, J. Wind Eng. Ind. Aerodyn. 98, 121-132 ) model of flow above changes in surface conditions has been used to investigate planetary boundary-layer flow over water with spatial changes in temperature, and to investigate situations leading to saturation and fog formation. Our turbulence closure includes the turbulent kinetic energy equation but we prefer to specify a height, surface roughness, Rossby number and local stability dependent, "master" length scale instead of a somewhat empirical dissipation or similar equation. Results show that fog can develop and extent to heights of order 100m in some conditions, depending on upstream profiles of wind, temperature and mixing ratio, and on solar radiation and the horizontal variations in water surface temperature.Next steps will involve validation against data being collected (by AMEC-Foster Wheeler in the Hibernia Management and Development Company Metocean project) over the Grand Banks and an interface with WRF and high resolution sea surface temperature data for forecasting fog conditions over the

Washout ratio of NaCl particles by raindrops, snowflakes and fog particles obtained using the large artificial climate experiment chamber at ACEF in IES

International Nuclear Information System (INIS)

Kawabata, Hitoshi; Kondo, Kunio; Hasegawa, Hidenao; Akata, Naofumi; Chikuchi, Yuki; Hisamatsu, Shun'ichi; Inaba, Jiro; Komagata, Yuuetsu

2007-01-01

Scavenging of NaCl particles by rainfall, snowfall and fog was examined in a large artificial climate experiment chamber in which the meteorological elements were controlled. The scavenging coefficient of Na by rainfall and snowfall were obtained using Na concentrations in air and precipitation. The washout ratio of Na by fog was also measured using Na concentrations in air and fog water. The scavenging coefficients by snowfall were found to be larger than those by rainfall, and showed that the removal efficiency of the former was higher than that of the latter. The coefficients by both rainfall and snowfall increased linearly with precipitation intensity. When the average diameters of fog droplets were the same, the washout ratio of Na by fog increased with fog liquid water content. On the other hand, when liquid water contents were the same, the washout ratio decreased with increasing average diameter of fog droplets. The washout ratio of Na by fog exponentially increased with the total surface area of fog droplets. (author)

Simulation of Fog Oil Deposition During Military Training Operations

National Research Council Canada - National Science Library

Haehnel, Robert B

2008-01-01

...) obscurant on the ground using the SCIPuff aerosol transport model. Model results are compared to actual deposition of fog oil measure on the ground during two military training exercises in Alaska...

Possible connection between the East Asian summer monsoon and a swing of the haze-fog-prone area in eastern China

Science.gov (United States)

Liu, Qian; Cao, Ziqi; Sheng, Lifang; Diao, Yina; Wang, Wencai; Zhou, Yang; Qiu, Jingyi

2018-05-01

The summer monsoon has recently been hypothesized to influence haze-fog events over China, but the detailed processes involved have yet to be determined. In the present study, we found that the haze-fog-prone area swings over eastern China during boreal summer (May to September), coinciding with the movement of the subtropical monsoon convergence belt (hereinafter referred to simply as the "convergence belt"). Further investigation showed that the convergence belt modulates the spatial distribution of the haze-fog-prone area by altering the regional atmospheric conditions. When the warm and wet summer monsoon air mass pushes northwards and meets with cold air, a frontal zone (namely, the convergence belt) forms. The ascent of warm and wet air along the front strengthens the atmospheric stability ahead of the frontal zone, while the descent of cold and dry air weakens the vertical diffusion at the same place. These processes result in an asymmetric distribution of haze-fog along the convergence belt. Based on the criterion of absolute stability and downdraft, these atmospheric conditions favorable for haze-fog are able to identify 57-79% of haze-fog-prone stations, and the anticipation accuracy is 61-71%. After considering the influence of air pollutants on haze-fog occurrence, the anticipation accuracy rises to 78-79%. Our study reveals a connection between local haze-fog weather phenomena and regional atmospheric conditions and large-scale circulation, and demonstrates one possible mechanism for how the summer monsoon influences the distribution of haze-fog in eastern China.

Helicopter Toy and Lift Estimation

Science.gov (United States)

Shakerin, Said

2013-01-01

A $1 plastic helicopter toy (called a Wacky Whirler) can be used to demonstrate lift. Students can make basic measurements of the toy, use reasonable assumptions and, with the lift formula, estimate the lift, and verify that it is sufficient to overcome the toy's weight. (Contains 1 figure.)

Understanding the role of fog in forest hydrology: Stable isotopes as tools for determining input and partitioning of cloud water in montane forests

Science.gov (United States)

Scholl, M.; Eugster, W.; Burkard, R.

2011-01-01

Understanding the hydrology of tropical montane cloud forests (TMCF) has become essential as deforestation of mountain areas proceeds at an increased rate worldwide. Passive and active cloud-water collectors, throughfall and stemflow collectors, visibility or droplet size measurements, and micrometeorological sensors are typically used to measure the fog water inputs to ecosystems. In addition, stable isotopes may be used as a natural tracer for fog and rain. Previous studies have shown that the isotopic signature of fog tends to be more enriched in the heavier isotopes 2H and 18O than that of rain, due to differences in condensation temperature and history. Differences between fog and rain isotopes are largest when rain is from synoptic-scale storms, and fog or orographic cloud water is generated locally. Smaller isotopic differences have been observed between rain and fog on mountains with orographic clouds, but only a few studies have been conducted. Quantifying fog deposition using isotope methods is more difficult in forests receiving mixed precipitation, because of limitations in the ability of sampling equipment to separate fog from rain, and because fog and rain may, under some conditions, have similar isotopic composition. This article describes the various types of fog most relevant to montane cloud forests and the importance of fog water deposition in the hydrologic budget. A brief overview of isotope hydrology provides the background needed to understand isotope applications in cloud forests. A summary of previous work explains isotopic differences between rain and fog in different environments, and how monitoring the isotopic signature of surface water, soil water and tree xylem water can yield estimates of the contribution of fog water to streamflow, groundwater recharge and transpiration. Next, instrumentation to measure fog and rain, and methods to determine isotopic concentrations in plant and soil water are discussed. The article concludes with

An unconventional mechanism of lift production during the downstroke in a hovering bird ( Zosterops japonicus)

Science.gov (United States)

Chang, Yu-Hung; Ting, Shang-Chieh; Liu, Chieh-Cheng; Yang, Jing-Tang; Soong, Chyi-Yeou

2011-11-01

An unconventional mechanism of ventral clap is exploited by hovering passerines to produce lift. Quantitative visualization of the wake flow, analysis of kinematics and evaluation of the transient lift force was conducted to dissect the biomechanical role of the ventral clap in the asymmetrical hovering flight of passerines. The ventral clap can first abate and then augment lift production during the downstroke; the net effect of the ventral clap on lift production is, however, positive because the extent of lift augmentation is greater than the extent of lift abatement. Moreover, the ventral clap is inferred to compensate for the zero lift production of the upstroke because the clapping wings induce a substantial elevation of the lift force at the end of the downstroke. Overall, our observations shed light on the aerodynamic function of the ventral clap and offer biomechanical insight into how a bird hovers without kinematically mimicking hovering hummingbirds.

A Satellite Based Fog Study of the Korean Peninsula

National Research Council Canada - National Science Library

McDonald, David K

2007-01-01

Fog has always been a difficult phenomenon to forecast. Its unpredictable nature and propensity to quickly decrease visibilities have had adverse effects on military operations for many years across the Korean peninsula...

Pattern recognition applied to infrared images for early alerts in fog

Science.gov (United States)

Boucher, Vincent; Marchetti, Mario; Dumoulin, Jean; Cord, Aurélien

2014-09-01

Fog conditions are the cause of severe car accidents in western countries because of the poor induced visibility. Its forecast and intensity are still very difficult to predict by weather services. Infrared cameras allow to detect and to identify objects in fog while visibility is too low for eye detection. Over the past years, the implementation of cost effective infrared cameras on some vehicles has enabled such detection. On the other hand pattern recognition algorithms based on Canny filters and Hough transformation are a common tool applied to images. Based on these facts, a joint research program between IFSTTAR and Cerema has been developed to study the benefit of infrared images obtained in a fog tunnel during its natural dissipation. Pattern recognition algorithms have been applied, specifically on road signs which shape is usually associated to a specific meaning (circular for a speed limit, triangle for an alert, …). It has been shown that road signs were detected early enough in images, with respect to images in the visible spectrum, to trigger useful alerts for Advanced Driver Assistance Systems.

Factors that influence properties of FOG deposits and their formation in sewer collection systems.

Science.gov (United States)

Iasmin, Mahbuba; Dean, Lisa O; Lappi, Simon E; Ducoste, Joel J

2014-02-01

Understanding the formation of Fat, Oil, and Grease (FOG) deposits in sewer systems is critical to the sustainability of sewer collection systems since they have been implicated in causing sewerage blockages that leads to sanitary sewer overflows (SSOs). Recently, FOG deposits in sewer systems displayed strong similarities with calcium-based fatty acid salts as a result of a saponification reaction. The objective of this study was to quantify the factors that may affect the formation of FOG deposits and their chemical and rheological properties. These factors included the types of fats used in FSEs, environmental conditions (i.e. pH and temperature), and the source of calcium in sewer systems. The results of this study showed that calcium content in the calcium based salts seemed to depend on the solubility limit of the calcium source and influenced by pH and temperature conditions. The fatty acid profile of the calcium-based fatty acid salts produced under alkali driven hydrolysis were identical to the profile of the fat source and did not match the profile of field FOG deposits, which displayed a high fraction of palmitic, a long chain saturated fatty acid. It is hypothesized that selective microbial metabolism of fats and/or biologically induced hydrogenation may contribute to the FOG deposit makeup in sewer system. Therefore, selective removal of palmitic in pretreatment processes may be necessary prior to the discharge of FSE wastes into the sewer collection system. Copyright © 2013 Elsevier Ltd. All rights reserved.

Bioinspired conical copper wire with gradient wettability for continuous and efficient fog collection.

Science.gov (United States)

Ju, Jie; Xiao, Kai; Yao, Xi; Bai, Hao; Jiang, Lei

2013-11-06

Inspired by the efficient fog collection on cactus spines, conical copper wires with gradient wettability are fabricated through gradient electrochemical corrosion and subsequent gradient chemical modification. These dual-gradient copper wires' fog-collection ability is demonstrated to be higher than that of conical copper wires with pure hydrophobic surfaces or pure hydrophilic surfaces, and the underlying mechanism is also analyzed. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lambda-Lifting in Quadratic Time

DEFF Research Database (Denmark)

Danvy, Olivier; Schultz, Ulrik Pagh

2002-01-01

Lambda-lifting is a program transformation that is used in compilers, partial evaluators, and program transformers. In this article, we show how to reduce its complexity from cubic time to quadratic time, and we present a flow-sensitive lambda-lifter that also works in quadratic time. Lambda-lifting...... that yields the cubic factor in the traditional formulation of lambda-lifting, which is due to Johnsson. This search is carried out by computing a transitive closure. To reduce the complexity of lambda-lifting, we partition the call graph of the source program into strongly connected components, based...... of lambda-lifting from O(n^3) to O(n^2) . where n is the size of the program. Since a lambda-lifter can output programs of size O(n^2), our algorithm is asympotically optimal....

Lambda-Lifting in Quadratic Time

DEFF Research Database (Denmark)

Danvy, Olivier; Schultz, Ulrik Pagh

2003-01-01

Lambda-lifting is a program transformation that is used in compilers, partial evaluators, and program transformers. In this article, we show how to reduce its complexity from cubic time to quadratic time, and we present a flow-sensitive lambda-lifter that also works in quadratic time. Lambda-lifting...... that yields the cubic factor in the traditional formulation of lambda-lifting, which is due to Johnsson. This search is carried out by computing a transitive closure. To reduce the complexity of lambda-lifting, we partition the call graph of the source program into strongly connected components, based...... of lambda-lifting from O(n^3) to O(n^2) . where n is the size of the program. Since a lambda-lifter can output programs of size O(n^2), our algorithm is asympotically optimal....

Lambda-Lifting in Quadratic Time

DEFF Research Database (Denmark)

Danvy, Olivier; Schultz, Ulrik Pagh

2004-01-01

Lambda-lifting is a program transformation that is used in compilers, partial evaluators, and program transformers. In this article, we show how to reduce its complexity from cubic time to quadratic time, and we present a flow-sensitive lambda-lifter that also works in quadratic time. Lambda-lifting...... that yields the cubic factor in the traditional formulation of lambda-lifting, which is due to Johnsson. This search is carried out by computing a transitive closure. To reduce the complexity of lambda-lifting, we partition the call graph of the source program into strongly connected components, based...... of lambda-lifting from O(n^3) to O(n^2) . where n is the size of the program. Since a lambda-lifter can output programs of size O(n^2), our algorithm is asympotically optimal....

Three-dimensional hierarchical structures for fog harvesting.

Science.gov (United States)

Andrews, H G; Eccles, E A; Schofield, W C E; Badyal, J P S

2011-04-05

Conventional fog-harvesting mechanisms are effectively pseudo-2D surface phenomena in terms of water droplet-plant interactions. In the case of the Cotula fallax plant, a unique hierarchical 3D arrangement formed by its leaves and the fine hairs covering them has been found to underpin the collection and retention of water droplets on the foliage for extended periods of time. The mechanisms of water capture and release as a function of the surface 3D structure and chemistry have been identified. Of particular note is that water is retained throughout the entirety of the plant and held within the foliage itself (rather than in localized regions). Individual plant hairs form matlike structures capable of supporting water droplets; these hairs wrap around water droplets in a 3D fashion to secure them via a fine nanoscale groove structure that prevents them from easily falling to the ground.

Lifting devices with minimum effort for testing, maintenance and repair at the example of a lifting rig for core internals

Energy Technology Data Exchange (ETDEWEB)

Pache, Martin [Westinghouse Electric Germany GmbH (Germany); Wiesendanger, Robert [Kernkraftwerk Beznau, NOK (Switzerland)

2008-07-01

Beznau is a Westinghouse built nuclear power plant in the Aargau area Switzerland. It consists of two PWR units, each providing 365 MWe net capacity. The units were set into operation in 1969 and 1972, respectively, and hold an unlimited license for operation, provided they continue to fulfill current legal and security requirements. Beznau's previous lifting rigs for core internals required a high effort in testing and maintenance. Moreover, a damage to one of the rigs nearly resulted in the inoperability of the rig. However, no element of the load chain was affected, so there was no danger of a crash, but it could have caused an extended outage. Hence, it was decided to replace the lifting rigs with a state-of-the-art functional design that reflects modern requirements on maintenance and testing. Although the plant was built to ASME standards and codes, the new lifting rigs have been designed to German KTA code for lifting devices (KTA 3902 / 3903 for equipment with increased requirements, as per section 4.3 of KTA 3902). Given KTA's demands on periodic testing, one main requirement on the new design was to minimize the testing effort for the new rigs. (orig.)

Methods for Assessing the Impact of Fog Oil Smoke on Availability, Palatability, & Food Quality of Relevant Life Stages of Insects for Threatened and Endangered Species

Energy Technology Data Exchange (ETDEWEB)

Driver, Crystal J.; Strenge, Dennis L.; Su, Yin-Fong; Cullinan, Valerie I.; Herrington, Ricky S.; Saunders, Danielle L.; Rogers, Lee E.

2007-04-01

A methodology for quantifying population dynamics and food source value of insect fauna in areas subjected to fog oil smoke was developed. Our approach employed an environmentally controlled re-circulating wind tunnel outfitted with a high-heat vaporization and re-condensation fog oil generator that has been shown to produce aerosols of comparable chemistry and droplet-size distribution as those of field releases of the smoke. This method provides reproducible exposures of insects under realistic climatic and environmental conditions to fog oil aerosols that duplicate chemical and droplet-size characteristics of field releases of the smoke. The responses measured take into account reduction in food sources due to death and to changes in availability of relevant life stages of insects that form the prey base for the listed Threatened and Endangered Species. The influence of key environmental factors, wind speed and canopy structure on these responses were characterized. Data generated using this method was used to develop response functions related to particle size, concentration, wind speed, and canopy structure that will allow military personnel to assess and manage impacts to endangered species from fog oil smoke used in military training.

High-Efficiency Fog Collector: Water Unidirectional Transport on Heterogeneous Rough Conical Wires.

Science.gov (United States)

Xu, Ting; Lin, Yucai; Zhang, Miaoxin; Shi, Weiwei; Zheng, Yongmei

2016-12-27

An artificial periodic roughness-gradient conical copper wire (PCCW) can be fabricated by inspiration from cactus spines and wet spider silks. PCCW can harvest fog on periodic points of the conical surface from air and transports the drops for a long distance without external force, which is attributed to dynamic as-released energy generated from drop deformation in drop coalescence, in addition to both gradients of geometric curve (inducing Laplace pressure) and periodic roughness (inducing surface energy difference). It is found that the ability of fog collection can be related to various tilt-angle wires, thus a fog collector with an array system of PCCWs is further designed to achieve a continuous process of efficient water collection. As a result, the effect of water collection on PCCWs is better than previous results. These findings are significant to develop and design materials with water collection and water transport for promising application in fogwater systems to ease the water crisis.

Atmospheric pollutants in fog and rain events at the northwestern mountains of the Iberian Peninsula

Energy Technology Data Exchange (ETDEWEB)

Fernández-González, Ricardo; Yebra-Pimentel, Iria; Martínez-Carballo, Elena [Nutrition and Bromatology Group, Analytical and Food Chemistry Department, Faculty of Food Science and Technology, University of Vigo, Ourense Campus, E32004 Ourense (Spain); Simal-Gándara, Jesús, E-mail: jsimal@uvigo.es [Nutrition and Bromatology Group, Analytical and Food Chemistry Department, Faculty of Food Science and Technology, University of Vigo, Ourense Campus, E32004 Ourense (Spain); Pontevedra-Pombal, Xabier, E-mail: xabier.pombal@usc.es [Soil Science and Agricultural Chemistry Department, Faculty of Biology, University of Santiago de Compostela, Santiago Campus, E15782 Santiago de Compostela (Spain)

2014-11-01

Atmospheric polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) are persistent organic pollutants (POPs) and exist in gas and particle phases, as well as dissolved or suspended in precipitation (fog or rain). While the hydrosphere is the main reservoir for PAHs, the atmosphere serves as the primary route for global transport of PCBs. In this study, fog and rain samples were collected during fourteen events from September 2011 to April 2012 in the Xistral Mountains, a remote range in the NW Iberian Peninsula. PAH compounds [especially of low molecular weight (LMW)] were universally found, but mainly in the fog-water samples. The total PAH concentration in fog-water ranged from non-detected to 216 ng · L{sup −1} (mean of 45 ng · L{sup −1}), and was much higher in fall than in winter. Total PAH levels in the rain and fog events varied from non-detected to 1272 and 33 ng · L{sup −1} for, respectively, LMW and high molecular weight (HMW) PAHs. Diagnostic ratio analysis (LMW PAHs/HMW PAHs) suggested that petroleum combustion was the dominant contributor to PAHs in the area. Total PCB levels in the rain and fog events varied from non-detected to 305 and 91 ng · L{sup −1} for, respectively, PCBs with 2–3 Cl atoms and 5–10 Cl atoms. PCBs, especially those with 5–10 Cl atoms, were found linked to rain events. The occurrence of the most volatile PCBs, PCBs with 2–3 Cl atoms, is related to wind transport from far away sources, whereas the occurrence of PCBs with 5–10 Cl atoms seems to be related with the increase of its deposition during rainfall at the end of summer and fall. The movement of this fraction of PCBs is facilitated by its binding to air-suspended particles, whose concentrations usually show an increase as the result of a prolonged period of drought in summer. - Highlights: • There is no work about both PAHs and PCBs in fog-rain events. • None of the existing works is about the case of the northwestern mountains

Atmospheric pollutants in fog and rain events at the northwestern mountains of the Iberian Peninsula

International Nuclear Information System (INIS)

Fernández-González, Ricardo; Yebra-Pimentel, Iria; Martínez-Carballo, Elena; Simal-Gándara, Jesús; Pontevedra-Pombal, Xabier

2014-01-01

Atmospheric polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) are persistent organic pollutants (POPs) and exist in gas and particle phases, as well as dissolved or suspended in precipitation (fog or rain). While the hydrosphere is the main reservoir for PAHs, the atmosphere serves as the primary route for global transport of PCBs. In this study, fog and rain samples were collected during fourteen events from September 2011 to April 2012 in the Xistral Mountains, a remote range in the NW Iberian Peninsula. PAH compounds [especially of low molecular weight (LMW)] were universally found, but mainly in the fog-water samples. The total PAH concentration in fog-water ranged from non-detected to 216 ng · L −1 (mean of 45 ng · L −1 ), and was much higher in fall than in winter. Total PAH levels in the rain and fog events varied from non-detected to 1272 and 33 ng · L −1 for, respectively, LMW and high molecular weight (HMW) PAHs. Diagnostic ratio analysis (LMW PAHs/HMW PAHs) suggested that petroleum combustion was the dominant contributor to PAHs in the area. Total PCB levels in the rain and fog events varied from non-detected to 305 and 91 ng · L −1 for, respectively, PCBs with 2–3 Cl atoms and 5–10 Cl atoms. PCBs, especially those with 5–10 Cl atoms, were found linked to rain events. The occurrence of the most volatile PCBs, PCBs with 2–3 Cl atoms, is related to wind transport from far away sources, whereas the occurrence of PCBs with 5–10 Cl atoms seems to be related with the increase of its deposition during rainfall at the end of summer and fall. The movement of this fraction of PCBs is facilitated by its binding to air-suspended particles, whose concentrations usually show an increase as the result of a prolonged period of drought in summer. - Highlights: • There is no work about both PAHs and PCBs in fog-rain events. • None of the existing works is about the case of the northwestern mountains of the Iberian

The Challenge of Forecasting the Onset and Development of Radiation Fog Using Mesoscale Atmospheric Models

NARCIS (Netherlands)

Steeneveld, G.J.; Ronda, R.J.; Holtslag, A.A.M.

2015-01-01

The numerical weather prediction of radiation fog is challenging, as many models typically show large biases for the timing of the onset and dispersal of the fog, as well as for its depth and liquid water content. To understand the role of physical processes, i.e. turbulence, radiation, land-surface

Prevalence and associated features of self-reported freezing of gait in Parkinson disease: The DEEP FOG study.

Science.gov (United States)

Amboni, M; Stocchi, F; Abbruzzese, G; Morgante, L; Onofrj, M; Ruggieri, S; Tinazzi, M; Zappia, M; Attar, M; Colombo, D; Simoni, L; Ori, A; Barone, P; Antonini, A

2015-06-01

Freezing of Gait (FOG) is a common and disabling symptom in patients with Parkinson disease (PD). The relationship between FOG and dopaminergic medication is complex. The aim of the present study was to estimate the prevalence of self-reported FOG, its associated clinical features, and its relationship with wearing-off in a wide PD population. This is an observational multicenter study of 634 consecutive non-demented PD patients. Patients were identified either as freezers or non-freezers based on item-3 of the Freezing of Gait-Questionnaire. FOG was then classified as on, off and onoff freezing based on its relationship with wearing-off. Patients were assessed with Unified Parkinson's Disease Rating Scale, Hoehn and Yahr scale, 8-item Parkinson's disease Questionnaire, Mini-Mental State Examination. Data from 593 patients were analyzed, 325 (54.3%) were freezers of whom 200 (61.6%) experienced FOG only during off state (off-freezers), 6 (1.8%) only during on state and 119 (36.6%) either in on and off states or independently of dopaminergic response-related symptoms (onoff-freezers). Overall, freezers vs non-freezers had longer disease duration, more advanced disease and greater disability. Moreover, freezers more frequently reported wearing-off and experienced worse quality of life. Onoff-freezers vs off-freezers were older, more severely disabled, less likely to experience wearing-off, treated with lower levodopa equivalent daily dose and with poorer cognitive performance. Self-reported FOG is mainly recognizable in advanced PD and is associated with more disability and worse quality of life. Onoff-FOG may represent the result of under-treatment or rather interpretable as a distinct clinical entity. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evaluation of trace elements contamination in cloud/fog water at an elevated mountain site in Northern China.

Science.gov (United States)

Liu, Xiao-huan; Wai, Ka-ming; Wang, Yan; Zhou, Jie; Li, Peng-hui; Guo, Jia; Xu, Peng-ju; Wang, Wen-xing

2012-07-01

Totally 117 cloud/fog water samples were collected at the summit of Mt. Tai (1534m a.s.l.)-the highest mountain in the Northern China Plain. The results were investigated by a combination of techniques including back trajectory model, regional air quality and dust storm models, satellite observations and Principal Component Analysis. Elemental concentrations were determined by Inductively Coupled Plasma Mass Spectrometry, with stringent quality control measures. Higher elemental concentrations were found at Mt. Tai compared with those reported by other overseas studies. The larger proportions and higher concentrations of toxic elements such as Pb and As in cloud/fog water compared with those in rainwater at Mt. Tai suggests higher potential hazards of cloud/fog water as a source of contamination in polluted areas to the ecosystem. Peak concentrations of trace elements were frequently observed during the onset of cloud/fog events when liquid water contents of cloud/fog water were usually low and large amount of pollutants were accumulated in the ambient air. Inverse relationship between elemental concentrations and liquid water contents were only found in the samples with high electrical conductivities and liquid water contents lower than 0.3gm(-3). Affected mainly by the emissions of steel industries and mining activities, air masses transported from south/southwest of Mt. Tai were frequently associated with higher elemental concentrations. The element Mn is attributed to play an important role in the acidity of cloud/fog water. The composition of cloud/fog water influenced by an Asian dust storm event was reported, which was seldom found in the literature. Copyright © 2012 Elsevier Ltd. All rights reserved.

Statistical modelling of Fat, Oil and Grease (FOG) deposits in wastewater pump sumps.

Science.gov (United States)

Nieuwenhuis, Eva; Post, Johan; Duinmeijer, Alex; Langeveld, Jeroen; Clemens, François

2018-05-15

The accumulation of FOG (Fat, Oil and Grease) deposits in sewer pumping stations results in an increase in maintenance costs, malfunctioning of pumps and, a potential increase of wastewater spills in receiving open water bodies. It is thought that a variety of parameters (e.g. geometry of the pump sump, pump operation, socioeconomic parameters of the catchment) influences the built-up of FOG. Based on a database containing data of 126 pumping stations located in five Dutch municipalities a statistical model was built. It is shown that 3 parameters are most significant in explaining the occurrence of FOG deposits: mean income of the population in a catchment, the amount of energy (kinetic and potential) per m 3 per day and the density of restaurants, bars and hotels in a catchment. Further it is shown that there are significant differences between municipalities that can be traced back to the local 'design paradigm'. For example, in Amsterdam, the design philosophy of discharging in the pump sump under the water surface (and hence maintaining a low level of turbulence in the pump sump) results in an increase of the probability of the formation of FOG. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Forecasting Advective Sea Fog with the Use of Classification and Regression Tree Analyses for Kunsan Air Base

National Research Council Canada - National Science Library

Lewis, Danielle

2004-01-01

.... To date, there are no suitable methods developed for forecasting advective sea fog at Kunsan, primarily due to a lack of understanding of sea fog formation under various synoptic situations over the Yellow Sea...

An optimal control strategies using vaccination and fogging in dengue fever transmission model

Science.gov (United States)

Fitria, Irma; Winarni, Pancahayani, Sigit; Subchan

2017-08-01

This paper discussed regarding a model and an optimal control problem of dengue fever transmission. We classified the model as human and vector (mosquito) population classes. For the human population, there are three subclasses, such as susceptible, infected, and resistant classes. Then, for the vector population, we divided it into wiggler, susceptible, and infected vector classes. Thus, the model consists of six dynamic equations. To minimize the number of dengue fever cases, we designed two optimal control variables in the model, the giving of fogging and vaccination. The objective function of this optimal control problem is to minimize the number of infected human population, the number of vector, and the cost of the controlling efforts. By giving the fogging optimally, the number of vector can be minimized. In this case, we considered the giving of vaccination as a control variable because it is one of the efforts that are being developed to reduce the spreading of dengue fever. We used Pontryagin Minimum Principle to solve the optimal control problem. Furthermore, the numerical simulation results are given to show the effect of the optimal control strategies in order to minimize the epidemic of dengue fever.

Development of Advanced High Lift Leading Edge Technology for Laminar Flow Wings

Science.gov (United States)

Bright, Michelle M.; Korntheuer, Andrea; Komadina, Steve; Lin, John C.

2013-01-01

This paper describes the Advanced High Lift Leading Edge (AHLLE) task performed by Northrop Grumman Systems Corporation, Aerospace Systems (NGAS) for the NASA Subsonic Fixed Wing project in an effort to develop enabling high-lift technology for laminar flow wings. Based on a known laminar cruise airfoil that incorporated an NGAS-developed integrated slot design, this effort involved using Computational Fluid Dynamics (CFD) analysis and quality function deployment (QFD) analysis on several leading edge concepts, and subsequently down-selected to two blown leading-edge concepts for testing. A 7-foot-span AHLLE airfoil model was designed and fabricated at NGAS and then tested at the NGAS 7 x 10 Low Speed Wind Tunnel in Hawthorne, CA. The model configurations tested included: baseline, deflected trailing edge, blown deflected trailing edge, blown leading edge, morphed leading edge, and blown/morphed leading edge. A successful demonstration of high lift leading edge technology was achieved, and the target goals for improved lift were exceeded by 30% with a maximum section lift coefficient (Cl) of 5.2. Maximum incremental section lift coefficients ( Cl) of 3.5 and 3.1 were achieved for a blown drooped (morphed) leading edge concept and a non-drooped leading edge blowing concept, respectively. The most effective AHLLE design yielded an estimated 94% lift improvement over the conventional high lift Krueger flap configurations while providing laminar flow capability on the cruise configuration.

Foliar uptake of fog water and transport belowground alleviates drought effects in the cloud forest tree species, Drimys brasiliensis (Winteraceae).

Science.gov (United States)

Eller, Cleiton B; Lima, Aline L; Oliveira, Rafael S

2013-07-01

Foliar water uptake (FWU) is a common water acquisition mechanism for plants inhabiting temperate fog-affected ecosystems, but the prevalence and consequences of this process for the water and carbon balance of tropical cloud forest species are unknown. We performed a series of experiments under field and glasshouse conditions using a combination of methods (sap flow, fluorescent apoplastic tracers and stable isotopes) to trace fog water movement from foliage to belowground components of Drimys brasiliensis. In addition, we measured leaf water potential, leaf gas exchange, leaf water repellency and growth of plants under contrasting soil water availabilities and fog exposure in glasshouse experiments to evaluate FWU effects on the water and carbon balance of D. brasiliensis saplings. Fog water diffused directly through leaf cuticles and contributed up to 42% of total foliar water content. FWU caused reversals in sap flow in stems and roots of up to 26% of daily maximum transpiration. Fog water transported through the xylem reached belowground pools and enhanced leaf water potential, photosynthesis, stomatal conductance and growth relative to plants sheltered from fog. Foliar uptake of fog water is an important water acquisition mechanism that can mitigate the deleterious effects of soil water deficits for D. brasiliensis. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Out of the fog: Catalyzing integrative capacity in interdisciplinary research.

Science.gov (United States)

Piso, Zachary; O'Rourke, Michael; Weathers, Kathleen C

2016-04-01

Social studies of interdisciplinary science investigate how scientific collaborations approach complex challenges that require multiple disciplinary perspectives. In order for collaborators to meet these complex challenges, interdisciplinary collaborations must develop and maintain integrative capacity, understood as the ability to anticipate and weigh tradeoffs in the employment of different disciplinary approaches. Here we provide an account of how one group of interdisciplinary fog scientists intentionally catalyzed integrative capacity. Through conversation, collaborators negotiated their commitments regarding the ontology of fog systems and the methodologies appropriate to studying fog systems, thereby enhancing capabilities which we take to constitute integrative capacity. On the ontological front, collaborators negotiated their commitments by setting boundaries to and within the system, layering different subsystems, focusing on key intersections of these subsystems, and agreeing on goals that would direct further investigation. On the methodological front, collaborators sequenced various methods, anchored methods at different scales, validated one method with another, standardized the outputs of related methods, and coordinated methods to fit a common model. By observing the process and form of collaborator conversations, this case study demonstrates that social studies of science can bring into critical focus how interdisciplinary collaborators work toward an integrated conceptualization of study systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

[PM2.5 pollution and aerosol optical properties in fog and haze days during autumn and winter in Beijing area].

Science.gov (United States)

Zhao, Xiu-Juan; Pu, Wei-Wei; Meng, Wei; Ma, Zhi-Qiang; Dong, Fan; He, Di

2013-02-01

A study on the PM2.5 pollution and aerosol optical properties in haze-fog days was carried out from Sep. 1st to Dec. 7th, 2011 in Beijing area by using PM2.5 concentration, aerosol scattering coefficient (sigma sca) and absorption coefficient (sigma abs) measured under urban and rural environment. The effect of weather condition on the PM25 pollution and aerosol optical properties was discussed as well. The results showed that the PM2.5 concentration, sigma sca and sigma abs, were evidently higher in haze-fog days than those in non-haze-fog days. The average PM2.5 concentrations in haze-fog days with values of 97.6 microg m-3 and 64.4 microg.m-3 were as 3.3 and 4.8 times as those in non-haze-fog days at urban and rural stations, respectively. The higher PM2.5 concentration in urban area resulted in the more frequent fog and haze phenomena than that in rural area. The PM25 concentration, sigma sca, and sigma abs were significantly higher in urban area than that in rural area in mist days, while relatively close in mist-haze days. This difference suggested that the effect of regional transport of pollution was relatively evident in mist-haze days but weak in mist day. In fog days the sigma sca showed no evident difference between urban and rural area, and was the highest in all types of fog and haze weather. The scattering property of aerosol was the strongest in fog days. The different weather conditions resulted in various characteristics of spatial distribution of PM2.5 concentration, sigma sca and sigma abs, as well as the strength of PM2,5 pollution and aerosol extinction. The pollutants transported by the strong southwest wind above the boundary layer and subsided in the boundary layer companying with the local accumulation of pollutants due to the weak diffusion resulted in the most serious haze-fog episode with the strongest PM2.5 pollution and aerosol extinction.

Processes for the elimination of fogging on KDP crystals prior to and during use in laser systems

International Nuclear Information System (INIS)

Thomas, I.M.; Kozlowski, M.R.; Edwards, G.; Stanion, K.; Fuchs, B.

1992-01-01

The rate of surface fogging on KDP crystals has been associated with several parameters in the diamond turning and subsequent cleaning process. Fogging can also occur during use because of environmental degradation. We have determined that reaction of the KDP surfaces with additives in the diamond turning oil has been a major factor in fogging and have found a replacement oil that eliminates this effect. We have also developed an antireflective silicone-sol coating that also reduces surface environmental deterioration during use by a factor of four

Experimental FSO network availability estimation using interactive fog condition monitoring

Science.gov (United States)

Turán, Ján.; Ovseník, Łuboš

2016-12-01

Free Space Optics (FSO) is a license free Line of Sight (LOS) telecommunication technology which offers full duplex connectivity. FSO uses infrared beams of light to provide optical broadband connection and it can be installed literally in a few hours. Data rates go through from several hundreds of Mb/s to several Gb/s and range is from several 100 m up to several km. FSO link advantages: Easy connection establishment, License free communication, No excavation are needed, Highly secure and safe, Allows through window connectivity and single customer service and Compliments fiber by accelerating the first and last mile. FSO link disadvantages: Transmission media is air, Weather and climate dependence, Attenuation due to rain, snow and fog, Scattering of laser beam, Absorption of laser beam, Building motion and Air pollution. In this paper FSO availability evaluation is based on long term measured data from Fog sensor developed and installed at TUKE experimental FSO network in TUKE campus, Košice, Slovakia. Our FSO experimental network has three links with different physical distances between each FSO heads. Weather conditions have a tremendous impact on FSO operation in terms of FSO availability. FSO link availability is the percentage of time over a year that the FSO link will be operational. It is necessary to evaluate the climate and weather at the actual geographical location where FSO link is going to be mounted. It is important to determine the impact of a light scattering, absorption, turbulence and receiving optical power at the particular FSO link. Visibility has one of the most critical influences on the quality of an FSO optical transmission channel. FSO link availability is usually estimated using visibility information collected from nearby airport weather stations. Raw data from fog sensor (Fog Density, Relative Humidity, Temperature measured at each ms) are collected and processed by FSO Simulator software package developed at our Department. Based

Characterisation of FOGs in grease trap waste from the processing of chickens in Thailand.

Science.gov (United States)

Nitayapat, Nuttakan; Chitprasert, Pakamon

2014-06-01

Industrial firms that kill and process chickens generate wastewater that contains fat, oil, and grease (FOG). The FOGs are located in the fatty waste that is collected by floatation in grease traps. Chemical and physical characterisation of FOGs would provide useful information that would help in the development of methods designed to decrease the extent of pollution caused by disposal of the waste and to utilise commercially some of its lipid constituents. Employing these methods would enhance the profitability and competitive potential of these commercial organisations. Samples of grease trap waste from 14 firms in central Thailand have been examined. Due to the very different schemes of waste management employed by these firms, the physical appearance of their fatty wastes showed considerable variation. The chemical and physical properties of the FOGs present in these wastes showed considerable variation also. Large amounts of free fatty acids (10-70% as oleic acid) were detected in most of the 14 wastes and palmitic, cis-9-oleic, cis,cis-9,12-linoleic, stearic, and palmitoleic acids were the predominant species of free and esterified acids. Most of the FOGs were solid at temperatures below 40 °C. Many of them contained traces of heavy metals (Cu and Pb) and some contained traces of the pesticides dimethoate and cypermethrin. The content of these potentially hazardous substances would have to be considered very carefully before discarding the fatty wastes and during the development of methods designed to isolate their potentially profitable lipid constituents. Copyright © 2013 Elsevier Ltd. All rights reserved.

Conditions to generate Steam Fog Occurred around the Chungju Lake in the South Korea

Science.gov (United States)

Byungwoo, J.

2017-12-01

We have collected the field observation data of the steam fog occurred around the Chungju Lake in the South Korea for 3 years(2014 2016) and analyzed conditions in which the steam fog occurred. The Chungju Lake is an artificial lake made by the Chungju Dam with a water storage of 2.7 billion tons, which is the second largest in South Korea. The Chungju Dam have discharged water of the average 2.2 million tons downstream to produce electricity per day. The drainage water heats downstream of the Chungju dam and the air above water surface of downstream of that. When the warm, humid air above the downstream water mixed with cold air mass, it caused "steam fog" around the downstream of Chungju lake regardless of amount of the discharged water. The condition that promote the generation of steam fog in autumn and winter is as follows: (1) cloudless night with light winds below 1.5 m/s. (2) The differences between the temperature of discharged water from the Chungju Dam and the air temperature above the discharged water varied from 3° to 15° in autumn, from 15° to 20° in winter respectively. (3) When stream fog was generated, sensible heat flux ranged in autumn from 5 to 15 W/m2, in winter from 15 to 20 W/m2 respectively. Latent heat flux ranged in autumn from 15 to 20 W/m2, in winter from 10 to 15 W/m2 respectively.

Designing the fog : towards an intranet of things

NARCIS (Netherlands)

Funk, Mathias

2018-01-01

The Fog of Things, ubiquitous computing in local contexts, is a reality now. The Internet of Things has arrived, although users use and perceive it rather as Internet of Thing [sic!]. Data and information flows vertically, not horizontally through the connected Everyday and promises of convenience

Aqueous greenhouse species in clouds, fogs, and aerosols

International Nuclear Information System (INIS)

Marley, N.A.; Gaffney, J.S.; Cunningham, M.M.

1993-01-01

Greenhouse effects from fossil fuel combustion leading to increased concentrations of primary and secondary greenhouse gases (e.g., CO-2, ozone, etc.) have received considerable attention. More recently, it has been suggested that clouds, aerosols, and fogs can play opposing roles in climate forcing by scattering or absorbing incoming solar radiation as well as by absorbing long-wave radiation as it escapes into space. The total effect on the radiation balance depends on the relative magnitude of these opposing forces, which in turn will depend on the composition of the aqueous phase. This work describes the measurement of water-soluble infrared absorbers which can contribute to the long-wave radiative forcing of clouds, fogs, and aerosols. Aqueous species which have been characterized include sulfate, nitrate, formate, acetate, oxalate, phenol, p-nitrophenol, ammonium, bicarbonate, formaldehyde, methanol, and ethanol. Infrared absorption band positions and band strengths have been determined, and their relative effects on radiative forcing are discussed

FogBank: a single cell segmentation across multiple cell lines and image modalities.

Science.gov (United States)

Chalfoun, Joe; Majurski, Michael; Dima, Alden; Stuelten, Christina; Peskin, Adele; Brady, Mary

2014-12-30

Many cell lines currently used in medical research, such as cancer cells or stem cells, grow in confluent sheets or colonies. The biology of individual cells provide valuable information, thus the separation of touching cells in these microscopy images is critical for counting, identification and measurement of individual cells. Over-segmentation of single cells continues to be a major problem for methods based on morphological watershed due to the high level of noise in microscopy cell images. There is a need for a new segmentation method that is robust over a wide variety of biological images and can accurately separate individual cells even in challenging datasets such as confluent sheets or colonies. We present a new automated segmentation method called FogBank that accurately separates cells when confluent and touching each other. This technique is successfully applied to phase contrast, bright field, fluorescence microscopy and binary images. The method is based on morphological watershed principles with two new features to improve accuracy and minimize over-segmentation. First, FogBank uses histogram binning to quantize pixel intensities which minimizes the image noise that causes over-segmentation. Second, FogBank uses a geodesic distance mask derived from raw images to detect the shapes of individual cells, in contrast to the more linear cell edges that other watershed-like algorithms produce. We evaluated the segmentation accuracy against manually segmented datasets using two metrics. FogBank achieved segmentation accuracy on the order of 0.75 (1 being a perfect match). We compared our method with other available segmentation techniques in term of achieved performance over the reference data sets. FogBank outperformed all related algorithms. The accuracy has also been visually verified on data sets with 14 cell lines across 3 imaging modalities leading to 876 segmentation evaluation images. FogBank produces single cell segmentation from confluent cell

Dynamic response of Hovercraft lift fans

Science.gov (United States)

Moran, D. D.

1981-08-01

Hovercraft lift fans are subjected to varying back pressure due to wave action and craft motions when these vehicles are operating in a seaway. The oscillatory back pressure causes the fans to perform dynamically, exhibiting a hysteresis type of response and a corresponding degradation in mean performance. Since Hovercraft motions are influenced by variations in lift fan pressure and discharge, it is important to understand completely the nature of the dynamic performance of lift fans in order to completely solve the Hovercraft seakeeping problem. The present study was performed to determine and classify the instabilities encountered in a centrifugal fan operating against time-varying back pressure. A model-scale experiment was developed in which the fan discharge was directed into a flow-measuring device, terminating in a rotating valve which produced an oscillatory back pressure superimposed upon a mean aerodynamic resistance. Pressure and local velocity were measured as functions of time at several locations in the fan volute. The measurements permitted the identification of rotating (or propagating) stall in the impeller. One cell and two cell configurations were classified and the transient condition connecting these two configurations was observed. The mechanisms which lead to rotating stall in a centrifugal compressor are presented and discussed with specific reference to Hovercraft applications.

Ecosystem Food Web Lift-The-Flap Pages

Science.gov (United States)

Atwood-Blaine, Dana; Rule, Audrey C.; Morgan, Hannah

2016-01-01

In the lesson on which this practical article is based, third grade students constructed a "lift-the-flap" page to explore food webs on the prairie. The moveable papercraft focused student attention on prairie animals' external structures and how the inferred functions of those structures could support further inferences about the…

Spatial and Temporal Analysis of Winter Fog Episodes over South Asia by exploiting ground-based and satellite observations

Science.gov (United States)

Fahim Khokhar, Muhammad; Yasmin, Naila; Zaib, Naila; Murtaza, Rabia; Noreen, Asma; Ishtiaq, Hira; Khayyam, Junaid; Panday, Arnico

2016-04-01

The South Asian region in general and the Indo-Gangetic Plains (IGP) in particular hold about 1/6th of the world's population and is considered as one of the major hotspots with increasing air pollution. Due to growing population and globalization, South Asia is experiencing high transformations in the urban and industrial sectors. Fog is one of the meteorological/environmental phenomena which can generate significant social and economic problems especially havoc to air and road traffic. Meteorological stations provide information about the fog episodes only on the basis of point observation. Continuous monitoring as well as a spatially coherent picture of fog distribution can only be possible through the use of satellite imagery. Current study focus on winter fog episodes over South Asian region using Moderate Resolution Image Spectrometer (MODIS) Level 2 Terra Product and other MODIS Aerosol Product in addition to ground-based sampling and AERONET measurements. MODIS Corrected Reflectance RGBs are used to analyse the spatial extent of fog over study area. MOD04 level 2 Collection 6 data is used to study aerosol load and distribution which are further characterised by using aerosol type land product of MODIS. In order to study the variation of ground based observations from satellite data MODIS, AERONET and high volume air Sampler were used. Main objective of this study was to explore the spatial extent of fog, its causes and to analyse the Aerosol Optical Depth (AOD) over South Asia with particular focus over Indo-Gangetic Plains (IGP). Current studies show a descent increase in AOD from past few decades over South Asia and is contributing to poor air quality in the region due to growing population, urbanization, and industrialization. Smoke and absorbing aerosol are major constituent of fog over South Asia. Furthermore, winter 2014-15 extended span of Fog was also observed over South Asia. A significant correlation between MODIS (AOD) and AERONET Station (AOD

Cloud shading and fog drip influence the metabolism of a coastal pine ecosystem.

Science.gov (United States)

Carbone, Mariah S; Park Williams, A; Ambrose, Anthony R; Boot, Claudia M; Bradley, Eliza S; Dawson, Todd E; Schaeffer, Sean M; Schimel, Joshua P; Still, Christopher J

2013-02-01

Assessing the ecological importance of clouds has substantial implications for our basic understanding of ecosystems and for predicting how they will respond to a changing climate. This study was conducted in a coastal Bishop pine forest ecosystem that experiences regular cycles of stratus cloud cover and inundation in summer. Our objective was to understand how these clouds impact ecosystem metabolism by contrasting two sites along a gradient of summer stratus cover. The site that was under cloud cover ~15% more of the summer daytime hours had lower air temperatures and evaporation rates, higher soil moisture content, and received more frequent fog drip inputs than the site with less cloud cover. These cloud-driven differences in environmental conditions translated into large differences in plant and microbial activity. Pine trees at the site with greater cloud cover exhibited less water stress in summer, larger basal area growth, and greater rates of sap velocity. The difference in basal area growth between the two sites was largely due to summer growth. Microbial metabolism was highly responsive to fog drip, illustrated by an observed ~3-fold increase in microbial biomass C with increasing summer fog drip. In addition, the site with more cloud cover had greater total soil respiration and a larger fractional contribution from heterotrophic sources. We conclude that clouds are important to the ecological functioning of these coastal forests, providing summer shading and cooling that relieve pine and microbial drought stress as well as regular moisture inputs that elevate plant and microbial metabolism. These findings are important for understanding how these and other seasonally dry coastal ecosystems will respond to predicted changes in stratus cover, rainfall, and temperature. © 2012 Blackwell Publishing Ltd.

Analysis of Cumulonimbus (Cb), Thunderstorm and Fog for Izmir Adnan Menderes Airport

Science.gov (United States)

Avsar, Ercument

2016-07-01

Demand for airline transport has been increasing day by day with the development of the aviation industry in Turkey. Meteorological conditions are among the most important factors that influence aviation facilities. Meteorological events cause delays and cancellation of flights which create economic and time losses, and they even lead to accidents and breakups. The most important meteorological events that affect the takeoff and landing of airplanes can be listed as wind, runway visual range, cloud, rain, icing, turbulence, and low level windshear. Meteorological events that affect the aviation facilities most often in Adnan Menderes Airport (LTBJ), the fourth largest airport in Turkey in terms of air traffic, are fog, Cumulonimbus (Cb) clouds and thunderstorms (TS-Thunderstorm). Therefore, it is important to identify the occurrence time of these events based on the analysis of data over many years and do the flight plans based on this meteorological information in order to make the aviation facilities safer and without delays. In this study, statistical analysis on the formation of Cb clouds, thunderstorm and foggy days is conducted using observations produced for aviation (METAR) and special observers (SPECI). It is found that there are two types of fog that are observed most often at LTBJ, namely radiation and advection fogs, accordingly to the results of statistical analysis based on data from 2004 to 2014. Fog events are found to occur most often in the months of December and January, during 04:00 - 07:00 UTC time interval, between pressure values over 1015-1020 hPa, in 130-190 degree light breeze (1-5KT) and in temperature levels between 5°C and 8°C. Thunderstorm events recorded at LTBJ between the years 2004 and 2014 are most often observed in the months of January and February, in 120-210 degree gentle breeze winds (6-10KT), and in temperature levels between 8 and 18 °C. Key Words: Adnan Menderes International Airport, LTBJ, Fog, Thunderstorm (TS), Cb

Lift conference | 5-7 February

CERN Multimedia

2014-01-01

Since 2006, Lift Events explore the business and social implications of new technologies through the organisation of international event series and open innovation programs in Europe, Asia and America. The next conference will be held on 5-7 February in Geneva.   (Image: © Lift Conference) The Lift Conference is one of the leading conferences on innovation in Europe and a key annual meeting for individuals and organizations wishing to understand and anticipate trends and innovation. Held every year in February in Geneva (5-7 February 2014), the Lift Conference is a three-day event consisting of talks, interactive workshops, exhibitions, and discussions bringing together over 1’000 participants from all society’s sectors and industries in a dynamic and informal environment with the aim to learn, connect, share and leverage innovation opportunities.   Extraordinary speakers will take to the stage at Lift14: Porter Erisman, former VP of Alibaba.com turned...

Lift production through asymmetric flapping

Science.gov (United States)

Jalikop, Shreyas; Sreenivas, K. R.

2009-11-01

At present, there is a strong interest in developing Micro Air Vehicles (MAV) for applications like disaster management and aerial surveys. At these small length scales, the flight of insects and small birds suggests that unsteady aerodynamics of flapping wings can offer many advantages over fixed wing flight, such as hovering-flight, high maneuverability and high lift at large angles of attack. Various lift generating mechanims such as delayed stall, wake capture and wing rotation contribute towards our understanding of insect flight. We address the effect of asymmetric flapping of wings on lift production. By visualising the flow around a pair of rectangular wings flapping in a water tank and numerically computing the flow using a discrete vortex method, we demonstrate that net lift can be produced by introducing an asymmetry in the upstroke-to-downstroke velocity profile of the flapping wings. The competition between generation of upstroke and downstroke tip vortices appears to hold the key to understanding this lift generation mechanism.

Direct lifts of coupled cell networks

Science.gov (United States)

Dias, A. P. S.; Moreira, C. S.

2018-04-01

In networks of dynamical systems, there are spaces defined in terms of equalities of cell coordinates which are flow-invariant under any dynamical system that has a form consistent with the given underlying network structure—the network synchrony subspaces. Given a network and one of its synchrony subspaces, any system with a form consistent with the network, restricted to the synchrony subspace, defines a new system which is consistent with a smaller network, called the quotient network of the original network by the synchrony subspace. Moreover, any system associated with the quotient can be interpreted as the restriction to the synchrony subspace of a system associated with the original network. We call the larger network a lift of the smaller network, and a lift can be interpreted as a result of the cellular splitting of the smaller network. In this paper, we address the question of the uniqueness in this lifting process in terms of the networks’ topologies. A lift G of a given network Q is said to be direct when there are no intermediate lifts of Q between them. We provide necessary and sufficient conditions for a lift of a general network to be direct. Our results characterize direct lifts using the subnetworks of all splitting cells of Q and of all split cells of G. We show that G is a direct lift of Q if and only if either the split subnetwork is a direct lift or consists of two copies of the splitting subnetwork. These results are then applied to the class of regular uniform networks and to the special classes of ring networks and acyclic networks. We also illustrate that one of the applications of our results is to the lifting bifurcation problem.

Fogging low concentrated organic acid in a fattening pig unit – Effect on animal health and microclimate

Directory of Open Access Journals (Sweden)

Heiko Stein

2016-09-01

Although fogging of tartaric acid is limited to a concentration of 0.1% due to its irritating effect on the respiratory mucosa, reduction of microbial load can be achieved, but it would be enhanced by using more powerful fogging systems.

Fog-Harvesting Properties of Dryopteris marginata: Role of Interscalar Microchannels in Water-Channeling

Directory of Open Access Journals (Sweden)

Vipul Sharma

2018-04-01

Full Text Available Several flora and fauna species found in arid areas have adapted themselves to collect water by developing unique structures and to intake the collected moisture. Apart from the capture of the moisture and fog on the surface, water transport and collection both play an important part in fog-harvesting systems as it prevents the loss of captured water through evaporation and makes the surface available for the capture of water again. Here, we report the remarkable fog collection and water-channeling properties of Dryopteris marginata. The surface of D. marginata has developed an integrated system of multiscale channels so that the water spreads quickly and is transported via these channels very efficiently. These integrated multiscale channels have also been replicated using a facile soft lithography technique to prepare biomimetic surfaces and it has been proved that it is the surface architecture that plays a role in the water transport rather than the material’s properties (waxes present on the surface of the leaves. Based on our studies, we infer that the microlevel hierarchy of the structures make the surface hydrophilic and the multiscale channels allow the efficient passage and transport of water. The understanding of the efficient and well-directed water transport and collection in D. marginata is expected to provide valuable insights to design efficient surfaces for fog-harvesting applications.

Examining the impacts of ethanol (E85) versus gasoline photochemical production of smog in a fog using near-explicit gas- and aqueous-chemistry mechanisms

International Nuclear Information System (INIS)

Ginnebaugh, Diana L; Jacobson, Mark Z

2012-01-01

This study investigates the air quality impacts of using a high-blend ethanol fuel (E85) instead of gasoline in vehicles in an urban setting when a morning fog is present under summer and winter conditions. The model couples the near-explicit gas-phase Master Chemical Mechanism (MCM v. 3.1) with the extensive aqueous-phase Chemical Aqueous Phase Radical Mechanism (CAPRAM 3.0i) in SMVGEAR II, a fast and accurate ordinary differential equation solver. Summer and winter scenarios are investigated during a two day period in the South Coast Air Basin (SCAB) with all gasoline vehicles replaced by flex-fuel vehicles running on E85 in 2020. We find that E85 slightly increases ozone compared with gasoline in the presence or absence of a fog under summer conditions but increases ozone significantly relative to gasoline during winter conditions, although winter ozone is always lower than summer ozone. A new finding here is that a fog during summer may increase ozone after the fog disappears, due to chemistry alone. Temperatures were high enough in the summer to increase peroxy radical (RO 2 ) production with the morning fog, which led to the higher ozone after fog dissipation. A fog on a winter day decreases ozone after the fog. Within a fog, ozone is always lower than if no fog occurs. The sensitivity of the results to fog parameters like droplet size, liquid water content, fog duration and photolysis are investigated and discussed. The results support previous work suggesting that E85 and gasoline both enhance pollution with E85 enhancing pollution significantly more at low temperatures. Thus, neither E85 nor gasoline is a ‘clean-burning’ fuel. (letter)

Fog and Rain Water Collection from Trees in the Dhofar Region in the Sultanate of Oman

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S. A. Abdul-Wahab

2009-06-01

Full Text Available This work had two purposes. The first was to measure and investigate the amount of fog and rain water collected by a sample of trees during the summer monsoon season in the mountains of the Dhofar region in the south of Oman. The second purpose was to assess the potential of trees with different leaf shapes, sizes and cross sectional canopy areas to collect fog and rain water in the area. In order to meet these purposes three different tree species, were selected for experimental investigation and field measurements. They included fig, lemon, and tamarind trees. The experiments were designed and implemented in the monsoon season of 2006, between the 13th of July and the 3rd of September. The daily measurements of water collection showed that the three species of tree have different water collection capacities. It was found that the fig tree collected the least water. The fog water collection of the fig tree over a period of 47 days between the 13th of July and the 3rd of September was 140.5 L/m2, or an average of 2.7 L/m2/d. The fog water collection of the lemon tree was 243.0 L/m2, or an average of 4.4 L/m2/d. In terms of potential collection of the tamarind tree, the results showed that it collected a fog water of 218.9 L/m2, or an average of 4.3 L/m2/d over the same period. The study contributes to the knowledge of how different tree species collect fog and rain water, and concludes with a set of recommendations.

Vertical vector face lift.

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Somoano, Brian; Chan, Joanna; Morganroth, Greg

2011-01-01