scholarly journals PHANTOM MODEL OF DISTRIBUTION OF VIRAL OBJECTS IN A PANDEMIC. PART 3

2021 ◽  
pp. 101-108
Author(s):  
Volodymyr Skytsiouk ◽  
Tatiana Klotchko
Keyword(s):  
Cell Surface ◽  
Biological Object ◽  
Dust Particles ◽  
Complex Flow ◽  
Complex Flows ◽  
Biological Origin ◽  
Near Surface ◽  
Phantom Model ◽  
Surrounding Space ◽  
Flow Propagation

The article states that the nature of the virus's interaction with objects during its spread in any environment is a significant problem. Therefore, taking into account the peculiarities of such a complex fractional composition of flows can make it possible to determine the nature of the interaction of the object, in particular biological, with complex particles of viral flows when touching. The author's previous works consider the peculiarities of the spread of viruses in the surrounding space of the pandanus zone of the object under the condition of a single fraction of the particle, ie in the near-surface layer. Of course, to better understand the nature of the interaction of viral flows with objects of possible infection, it is necessary to analyze the processes of virion’s touching to the cell surface of a biological object. The studied regularities of the occurrence of motion forces in environment’s space made it possible to determine the geometric parameters of the spread of viral formations near the object’s surface. The main purpose of this study was to continue to create a model of interaction of complex flows with different fractions that are carriers of viruses as material particles in the environment, in terms of modeling the motion and touching the surface of the object at different types of touch depending on their interaction. The mechanical movement of the virus during contact, rather than stages, as in biological processes, is considered. The nature of the interaction of complex viruses’s streams with objects of biological origin is modeled. To study the peculiarities of the interaction of the virion with the cell surface of a biological object, it is necessary to consider the flow complex of particles of different fractions, i.e. microstructures of virions that accompany drip suspension flows of body fluids and foreign dust particles. Thus, we can distinguish the motion of a complex of particles that comes into contact with object’s surface, as well as the possibility of breaking out individual microparticles, virions, which can emerge from the complex flow and propagate separately from others. At the same time, the dependences of the energy complex, which forms the flow of complex elements-particles of different fractions, which can take into account the range of flow propagation and features of motion kinematics, are determined. In further research, the phantom model of the propagation of fluxes of viral objects in space requires modeling the temporal parameters of the motion of fluxes of complex particles during the propagation to the object’s surface of various origins, including biological object.

scholarly journals Large Temperature Fluctuations due to Cold-Air Pool Displacement along the Lee Slope of a Desert Mountain

2017 ◽  
Vol 56 (4) ◽  
pp. 1083-1098 ◽  
Author(s):  
Matthew E. Jeglum ◽  
Sebastian W. Hoch ◽  
Derek D. Jensen ◽  
Reneta Dimitrova ◽  
Zachariah Silver
Keyword(s):  
Low Frequency ◽  
Temperature Fluctuations ◽  
Atmospheric Modeling ◽  
Large Temperature ◽  
Complex Flow ◽  
Near Surface ◽  
Cold Air ◽  
Flow Interactions ◽  
Initial Drop ◽  
Program Temperature

AbstractLarge temperature fluctuations (LTFs), defined as a drop of the near-surface temperature of at least 3°C in less than 30 min followed by a recovery of at least half of the initial drop, were frequently observed during the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) program. Temperature time series at over 100 surface stations were examined in an automated fashion to identify and characterize LTFs. LTFs occur almost exclusively at night and at locations elevated 50–100 m above the basin floors, such as the east slope of the isolated Granite Mountain (GM). Temperature drops associated with LTFs were as large as 13°C and were typically greatest at heights of 4–10 m AGL. Observations and numerical simulations suggest that LTFs are the result of complex flow interactions of stably stratified flow with a mountain barrier and a leeside cold-air pool (CAP). An orographic wake forms over GM when stably stratified southwesterly nocturnal flow impinges on GM and is blocked at low levels. Warm crest-level air descends in the lee of the barrier, and the generation of baroclinic vorticity leads to periodic development of a vertically oriented vortex. Changes in the strength or location of the wake and vortex cause a displacement of the horizontal temperature gradient along the slope associated with the CAP edge, resulting in LTFs. This mechanism explains the low frequency of LTFs on the west slope of GM as well as the preference for LTFs to occur at higher elevations later at night, as the CAP depth increases.

scholarly journals Faecal Pellets in Deep Marine Soft Clay Crusts: Implications for Hot-Oil Pipeline Design

2011 ◽  
Author(s):  
Matthew Y-H. Kuo ◽  
Malcolm D. Bolton
Keyword(s):  
Soft Clay ◽  
Faecal Pellet ◽  
Major Constituent ◽  
Biological Origin ◽  
Near Surface ◽  
Faecal Pellets ◽  
Oil Pipeline ◽  
Average Grain Size ◽  
Time Required ◽  
Pipeline Design

In recent years, the presence of crusts within near surface sediments found in deep water locations off the west coast of Angola has been of interest to hot-oil pipeline designers. The origin for these crusts is considered to be of biological origin, based on the observation of thousands of faecal pellets in natural crust core samples. This paper presents the results of laboratory tests undertaken on natural and faecal pellet-only samples. These tests investigate the role faecal pellets play in modifying the gemechanical behaviour of clayey sediments. It is found that faecal pellets are able to significantly alter both the strength and the average grain-size of natural sediments, and therefore, influence the permeability and stiffness. Hot-oil pipelines self-embed into and subsequent shear on crusts containing faecal pellets. Being able to predict the time required for installed pipelines to consolidate the underlying sediment and thus, how soon after pipe-laying, the interface strength will develop is of great interest to pipeline designers. It is concluded from wet-sieving samples before and after oedometer tests, that the process of pipe laying is unlikely to destroy pellets. They will therefore, be a major constituent of the sediment subject to soil-pipeline shearing behaviour during axial pipe-walking and lateral buckling. Based on the presented results, a discussion highlighting the key implications for pipeline design is therefore provided.

scholarly journals Characterization of smoke and dust episode over West Africa: comparison of MERRA-2 modeling with multiwavelength Mie–Raman lidar observations

2018 ◽  
Vol 11 (2) ◽  
pp. 949-969 ◽  
Author(s):  
Igor Veselovskii ◽  
Philippe Goloub ◽  
Thierry Podvin ◽  
Didier Tanre ◽  
Arlindo da Silva ◽  
...  
Keyword(s):  
West Africa ◽  
Mean Value ◽  
Dust Particles ◽  
Raman Lidar ◽  
Near Surface ◽  
Dust Layer ◽  
Extinction Coefficients ◽  
Surface Dust ◽  
Smoke Layer ◽  
Lidar Ratio

Abstract. Observations of multiwavelength Mie–Raman lidar taken during the SHADOW field campaign are used to analyze a smoke–dust episode over West Africa on 24–27 December 2015. For the case considered, the dust layer extended from the ground up to approximately 2000 m while the elevated smoke layer occurred in the 2500–4000 m range. The profiles of lidar measured backscattering, extinction coefficients, and depolarization ratios are compared with the vertical distribution of aerosol parameters provided by the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2). The MERRA-2 model simulated the correct location of the near-surface dust and elevated smoke layers. The values of modeled and observed aerosol extinction coefficients at both 355 and 532 nm are also rather close. In particular, for the episode reported, the mean value of difference between the measured and modeled extinction coefficients at 355 nm is 0.01 km−1 with SD of 0.042 km−1. The model predicts significant concentration of dust particles inside the elevated smoke layer, which is supported by an increased depolarization ratio of 15 % observed in the center of this layer. The modeled at 355 nm the lidar ratio of 65 sr in the near-surface dust layer is close to the observed value (70 ± 10) sr. At 532 nm, however, the simulated lidar ratio (about 40 sr) is lower than measurements (55 ± 8 sr). The results presented demonstrate that the lidar and model data are complimentary and the synergy of observations and models is a key to improve the aerosols characterization.

scholarly journals Aerial Imaging of Fluorescent Dye in the Near Shore

2014 ◽  
Vol 31 (6) ◽  
pp. 1410-1421 ◽  
Author(s):  
David B. Clark ◽  
Luc Lenain ◽  
Falk Feddersen ◽  
Emmanuel Boss ◽  
R. T. Guza
Keyword(s):  
Aerial Images ◽  
Complex Flow ◽  
Near Surface ◽  
Aerial Imaging ◽  
In Situ Calibration ◽  
Water Tracing ◽  
Near Shore ◽  
Rhodamine Wt ◽  
Image Pixels

Abstract Aerial images are used to quantify the concentration of fluorescent Rhodamine water tracing (WT) dye in turbid and optically deep water. Tracer releases near the shoreline of an ocean beach and near a tidal inlet were observed with a two-band multispectral camera and a pushbroom hyperspectral imager, respectively. The aerial observations are compared with near-surface in situ measurements. The ratio of upwelling radiance near the Rhodamine WT excitation and emission peaks varies linearly with the in situ dye concentrations for concentrations <20 ppb (r2 = 0.70 and r2 = 0.85–0.88 at the beach and inlet, respectively). The linear relationship allows for relative tracer concentration estimates without in situ calibration. The O(1 m) image pixels resolve complex flow structures on the inner shelf that transport and mix tracer.

scholarly journals Meteoroid impacts and dust particles in near-surface lunar exosphere

2016 ◽  
Vol 774 ◽  
pp. 012175 ◽  
Author(s):  
S I Popel ◽  
A P Golub’ ◽  
E A Lisin ◽  
Yu N Izvekova ◽  
B Atamaniuk ◽  
...  
Keyword(s):  
Dust Particles ◽  
Near Surface ◽  
Lunar Exosphere

scholarly journals NUMERICAL SIMULATION OF DUST-AIR FLOWS NEAR THE LOCAL VENTILATION EXTRACTION FROM DRILLING EQUIPMENT

2021 ◽  
Vol 6 (3) ◽  
pp. 36-46
Author(s):  
O. Tiron ◽  
K. Logachev
Keyword(s):  
Air Flow ◽  
Vertical Wall ◽  
Flow Simulation ◽  
Side Surface ◽  
Dust Particles ◽  
Maximum Diameter ◽  
Drilling Process ◽  
Air Flow Rate ◽  
Local Ventilation ◽  
Surrounding Space

A significant amount of dust is released during the drilling process. It negatively affects the cleanliness and ecology of the surrounding space, as well as human health. The design of a local extraction nozzle is proposed for dedusting the process of drilling concrete with standard drills. A computer model of the dust-air flow in the developed nozzle is created in the software package SolidWorks Flow Simulation. The dynamics of dust particles formed during drilling is numerically studied. The behavior of dust particles of different sizes is considered. It is proposed to use the value of the maximum diameter of dust particles completely captured by the suction channel as a criterion for the efficiency of dust particle capture. Three variants of the drilling plane arrangement are considered: floor, ceiling and vertical wall. The dependences of the maximum diameter of dust particles on the intake air flow rate, the distance of the extraction channel on the side surface of the nozzle to the place of its abutment to the drilling plane, and the radius of the suction channel are determined. The results obtained can be used to design and improve systems for capturing dust pollution generated during drilling. The formulated further directions of research are useful for researchers engaged in identifying the processes of capturing dust particles from mobile technological equipment.

scholarly journals Development of crystal orientation fabric in the Dome Fuji ice core in East Antarctica: implications for the deformation regime in ice sheets

2021 ◽  
Author(s):  
Tomotaka Saruya ◽  
Shuji Fujita ◽  
Yoshinori Iizuka ◽  
Atsushi Miyamoto ◽  
Hiroshi Ohno ◽  
...  
Keyword(s):  
Crystal Orientation ◽  
Ice Core ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Inverse Correlation ◽  
Chloride Ions ◽  
East Antarctica ◽  
Dust Particles ◽  
Near Surface ◽  
Deformation Regime

Abstract. The crystal orientation fabric (COF) of a polar ice sheet has a significant effect on the rheology of the sheet. With the aim of better understanding the deformation regime of ice sheets, the present work investigated the COF in the upper 80 % of the depth within the 3035 m long Dome Fuji Station ice core drilled at one of the dome summits in East Antarctica. Dielectric anisotropy (∆ε) data were acquired as a novel indicator of the vertical clustering of COF resulting from vertical compressional strain within the dome, at which the ice cover has an age of approximately 300 kyrs BP. The ∆ε values were found to exhibit a general increase moving in the depth direction, but with fluctuations over distances on the order of 10–102 m. In addition, significant decreases in ∆ε were found to be associated with depths corresponding to three major glacial to interglacial transitions. These changes in ∆ε are ascribed to variations in the deformational history caused by dislocation motion occurring from near-surface depths to deeper layers. Fluctuations in ∆ε over distances of less than 0.5 m exhibited a strong inverse correlation with at depths greater than approximately 1200 m, indicating that they were enhanced during the glacial/interglacial transitions. The ∆ε data also exhibited a positive correlation with the concentration of chloride ions together with an inverse correlation with the amount of dust particles in the ice core at greater depths corresponding to decreases in the degree of c-axis clustering. Finally, we found that fluctuations in ∆ε persisted to approximately 80 % of the total depth of the ice sheet. These data suggest that the factors determining the deformation of ice include the concentration of chloride ions and amount of dust particles, and that the layered contrast associated with the COF is preserved all the way from the near-surface to a depth corresponding to approximately 80 % of the thickness of the ice sheet. These findings provide important implications regarding further development of the COF under the various stress-strain configurations that the ice will experience in the deepest region, approximately 20 % of the total depth from the ice/bed interface.

scholarly journals Vertical distribution of aerosol optical properties in the Po Valley during the 2012 summer campaigns

2018 ◽  
Vol 18 (8) ◽  
pp. 5371-5389 ◽  
Author(s):  
Silvia Bucci ◽  
Paolo Cristofanelli ◽  
Stefano Decesari ◽  
Angela Marinoni ◽  
Silvia Sandrini ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Long Range ◽  
Mineral Dust ◽  
Dust Particles ◽  
Long Range Transport ◽  
Hygroscopic Growth ◽  
Limit Values ◽  
Near Surface ◽  
Po Valley ◽  
Range Transport

Abstract. Studying the vertical distribution of aerosol particle physical and chemical properties in the troposphere is essential to understand the relative importance of local emission processes vs. long-range transport for column-integrated aerosol properties (e.g. the aerosol optical depth, AOD, affecting regional climate) as well as for the aerosol burden and its impacts on air quality at the ground. The main objective of this paper is to investigate the transport of desert dust in the middle troposphere and its intrusion into the planetary boundary layer (PBL) over the Po Valley (Italy), a region considered one of the greatest European pollution hotspots for the frequency that particulate matter (PM) limit values are exceeded. Events of mineral aerosol uplift from local (soil) sources and phenomena of hygroscopic growth at the ground are also investigated, possibly affecting the PM concentration in the region as well. During the PEGASOS 2012 field campaign, an integrated observing–modelling system was set up based on near-surface measurements (particle concentration and chemistry), vertical profiling (backscatter coefficient profiles from lidar and radiosoundings) and Lagrangian air mass transport simulations by FLEXPART model. Measurements were taken at the San Pietro Capofiume supersite (44°39′ N, 11°37′ E; 11 m a.s.l.), located in a rural area relatively close to some major urban and industrial emissive areas in the Po Valley. Mt. Cimone (44°12′ N, 10°42′ E; 2165 m a.s.l.) WMO/GAW station observations are also included in the study to characterize regional-scale variability. Results show that, in the Po Valley, aerosol is detected mainly below 2000 m a.s.l. with a prevalent occurrence of non-depolarizing particles ( > 50 % throughout the campaign) and a vertical distribution modulated by the PBL daily evolution. Two intense events of mineral dust transport from northern Africa (19–21 and 29 June to 2 July) are observed, with layers advected mainly above 2000 m, but subsequently sinking and mixing in the PBL. As a consequence, a non-negligible occurrence of mineral dust is observed close to the ground ( ∼ 7 % of occurrence during a 1-month campaign). The observations unambiguously show Saharan dust layers intruding the Po Valley mixing layer and directly affecting the aerosol concentrations near the surface. Finally, lidar observations also indicate strong variability in aerosol on shorter timescales (hourly). Firstly, these highlight events of hygroscopic growth of anthropogenic aerosol, visible as shallow layers of low depolarization near the ground. Such events are identified during early morning hours at high relative humidity (RH) conditions (RH  > 80 %). The process is observed concurrently with high PM1 nitrate concentration (up to 15 µg cm−3) and hence mainly explicable by deliquescence of fine anthropogenic particles, and during mineral dust intrusion episodes, when water condensation on dust particles could instead represent the dominant contribution. Secondly, lidar images show frequent events (mean daily occurrence of  ∼  22 % during the whole campaign) of rapid uplift of mineral depolarizing particles in afternoon–evening hours up to 2000 m a.s.l. height. The origin of such particles cannot be directly related to long-range transport events, being instead likely linked to processes of soil particle resuspension from agricultural lands.

Study of Sand Particle Trajectories and Erosion Into the First Fan Stage of a Turbofan

2010 ◽  
Author(s):  
Adel Ghenaiet
Keyword(s):  
Gas Turbines ◽  
Solid Phase ◽  
Engine Performance ◽  
Suction Side ◽  
Dust Particles ◽  
Sand Particle ◽  
Computational Domain ◽  
Complex Flow ◽  
Particle Trajectories ◽  
Trailing Edges

Ingestion of dust particles by aero-engines or stationary gas turbines is inevitable when operating in extremely polluted environments. The impingements of particles on the surfaces of blades cause erosion damage and permanent losses in engine performance. This paper presents a study of the particle dynamics and erosion in the first stage of a turbofan. The steady flow field through the turbomachinery components was solved separately from the solid phase. The particle trajectories computations used a stochastic Lagrangian tracking code that implements probabilistic modeling for particle size rebound and fragmentation, and considers the eddy-lifetime concept for turbulence and the complex flow features near walls. The equations of a particle motion were solved in a stepwise manner using the seventh order RK-Fehlberg technique, whereas particle tracking in different cells of the computational domain used the finite element method. Computations of particle trajectories were carried out for sand particles MIL-E5007E (0–1000 microns) at low, mid and high concentrations. As the locations of impacts were predicted, erosion contours were estimated and the subsequent blade deteriorations were assessed. The rotor blade shows a noticeable erosion of the blade leading and trailing edges almost from root to tip and a rounding of blade tip. Erosion patterns in the diffuser depict high erosion at blade leading and trailing edges and the erosion of pressure side is spreading almost from root to tip, in addition to erosion over the suction side. The actual findings may serve in improving erosion resistance of the blades in this fan stage.

scholarly journals Size distributions and temporal variations of biological aerosol particles in the Amazon rainforest characterized by microscopy and real-time UV-APS fluorescence techniques during AMAZE-08

2012 ◽  
Vol 12 (24) ◽  
pp. 11997-12019 ◽  
Author(s):  
J. A. Huffman ◽  
B. Sinha ◽  
R. M. Garland ◽  
A. Snee-Pollmann ◽  
S. S. Gunthe ◽  
...  
Keyword(s):  
Real Time ◽  
Inorganic Material ◽  
Aerosol Particles ◽  
Fungal Spores ◽  
Dust Particles ◽  
Laser Induce Fluorescence ◽  
Biological Origin ◽  
Biological Particles ◽  
Total Particle ◽  
Biological Aerosol Particles

Abstract. As a part of the AMAZE-08 campaign during the wet season in the rainforest of central Amazonia, an ultraviolet aerodynamic particle sizer (UV-APS) was operated for continuous measurements of fluorescent biological aerosol particles (FBAP). In the coarse particle size range (> 1 μm) the campaign median and quartiles of FBAP number and mass concentration were 7.3 × 104 m−3 (4.0–13.2 × 104 m−3) and 0.72 μg m−3 (0.42–1.19 μg m−3), respectively, accounting for 24% (11–41%) of total particle number and 47% (25–65%) of total particle mass. During the five-week campaign in February–March 2008 the concentration of coarse-mode Saharan dust particles was highly variable. In contrast, FBAP concentrations remained fairly constant over the course of weeks and had a consistent daily pattern, peaking several hours before sunrise, suggesting observed FBAP was dominated by nocturnal spore emission. This conclusion was supported by the consistent FBAP number size distribution peaking at 2.3 μm, also attributed to fungal spores and mixed biological particles by scanning electron microscopy (SEM), light microscopy and biochemical staining. A second primary biological aerosol particle (PBAP) mode between 0.5 and 1.0 μm was also observed by SEM, but exhibited little fluorescence and no true fungal staining. This mode may have consisted of single bacterial cells, brochosomes, various fragments of biological material, and small Chromalveolata (Chromista) spores. Particles liquid-coated with mixed organic-inorganic material constituted a large fraction of observations, and these coatings contained salts likely from primary biological origin. We provide key support for the suggestion that real-time laser-induce fluorescence (LIF) techniques using 355 nm excitation provide size-resolved concentrations of FBAP as a lower limit for the atmospheric abundance of biological particles in a pristine environment. We also show some limitations of using the instrument for ambient monitoring of weakly fluorescent particles < 2 μm. Our measurements confirm that primary biological particles, fungal spores in particular, are an important fraction of supermicron aerosol in the Amazon and that may contribute significantly to hydrological cycling, especially when coated by mixed inorganic material.

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