scholarly journals Effects of ice particles shattering on the 2D-S probe

2011 ◽  
Vol 4 (7) ◽  
pp. 1361-1381 ◽  
Author(s):  
R. P. Lawson
Keyword(s):  
Particle Size ◽  
High Speed ◽  
Arrival Time ◽  
Primary Source ◽  
Time Algorithm ◽  
Post Processing ◽  
Cloud Particle ◽  
Ice Particles ◽  
Field Campaigns ◽  
Processing Techniques

Abstract. Recently, considerable attention has been focused on the issue of large ice particles shattering on the inlets and tips of cloud particle probes, which produces copious ice particles that can be mistakenly measured as real ice particles. Currently two approaches are being used to mitigate the problem: (1) Based on recent high-speed video in icing tunnels, probe tips have been designed that reduce the number of shattered particles that reach the probe sample volume, and (2) Post processing techniques such as image processing and using the arrival time of each individual particle. This paper focuses on exposing suspected errors in measurements of ice particle size distributions due to shattering, and evaluation of the two techniques used to reduce the errors. Data from 2D-S probes constitute the primary source of the investigation, however, when available comparisons with 2D-C and CIP measurements are also included. Korolev et al. (2010b) report results from a recent field campaign (AIIE) and conclude that modified probe tips are more effective than an arrival time algorithm when applied to 2D-C and CIP measurements. Analysis of 2D-S data from the AIIE and SPARTICUS field campaigns shows that modified probe tips significantly reduce the number of shattered particles, but that a particle arrival time algorithm is more effective than the probe tips designed to reduce shattering. A large dataset of 2D-S measurements with and without modified probe tips was not available from the AIEE and SPARTICUS field campaigns. Instead, measurements in regions with large ice particles are presented to show that shattering on the 2D-S with modified probe tips produces large quantities of small particles that are likely produced by shattering. Also, when an arrival time algorithm is applied to the 2D-S data, the results show that it is more effective than the modified probe tips in reducing the number of small (shattered) particles. Recent results from SPARTICUS and MACPEX show that 2D-S ice particle concentration measurements are more consistent with physical arguments and numerical simulations than measurements with older cloud probes from previous field campaigns. The analysis techniques in this paper can also be used to estimate an upper bound for the effects of shattering. For example, the additional spurious concentration of small ice particles can be measured as a function of the mass concentration of large ice particles. The analysis provides estimates of upper bounds on the concentration of natural ice, and on the remaining concentration of shattered ice particles after application of the post-processing techniques. However, a comprehensive investigation of shattering is required to quantify effects that arise from the multiple degrees of freedom associated with this process, including different cloud environments, probe geometries, airspeed, angle of attack, particle size and type.

scholarly journals Effects of ice particles shattering on optical cloud particle probes

2011 ◽  
Vol 4 (1) ◽  
pp. 939-968 ◽  
Author(s):  
R. P. Lawson
Keyword(s):  
Particle Size ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Arrival Time ◽  
Primary Source ◽  
Time Algorithm ◽  
Post Processing ◽  
Cloud Particle ◽  
Ice Particles ◽  
Processing Techniques

Abstract. Recently, considerable attention has been focused on the issue of large ice particles shattering on the inlets and tips of cloud particle probes, which produces copious ice particles that can be mistakenly measured as real ice particles. Currently two approaches are being used to mitigate the problem: (1) Based on recent high-speed video in icing tunnels, probe tips have been designed that reduce the number of shattered particles that reach the probe sample volume, and (2) Post processing techniques such as image processing and using the arrival time of each individual particle. This paper focuses on exposing suspected errors in measurements of ice particle size distributions due to shattering, and evaluation of the two techniques used to reduce the errors. Data from 2D-S probes constitute the primary source of our investigation, however, comparisons with 2D-C and CIP measurements are also included. Analysis of 2D-S data shows that a particle arrival time algorithm is more effective than probe tips designed to reduce shattering, although application of both techniques ought to be complementary. This finding contrasts results from a recent investigation that found that modified probe tips were more effective than an arrival time algorithm when applied to 2D-C and CIP measurements. The reason for these differing results may be linked to the improved ability of the 2D-S to image small ice particles. The analysis techniques in this paper can be used to estimate the effects of shattering. For example, the additional spurious concentration of (small) shattered ice particles can be measured as a function of the mass concentration of (large) ice particles. The analysis provides estimates of upper bounds on the concentration of natural ice, and on the remaining concentration of shattered ice particles after application of the post-processing techniques. However, a comprehensive investigation of shattering is required to quantify effects that arise from the multiple degrees of freedom associated with this process, including different cloud environments, probe geometries, airspeed, angle of attack, particle size and type.

scholarly journals Assessment of the performance of the inter-arrival time algorithm to identify ice shattering artifacts in cloud particle probe measurements

2015 ◽  
Vol 8 (2) ◽  
pp. 761-777 ◽  
Author(s):  
A. Korolev ◽  
P. R. Field
Keyword(s):  
Particle Size ◽  
Arrival Time ◽  
Time Algorithm ◽  
Sample Volume ◽  
Ice Crystals ◽  
Cloud Particle ◽  
Measured Concentration ◽  
Arrival Times ◽  
Microphysical Properties ◽  
The Impact

Abstract. Shattering presents a serious obstacle to current airborne in situ methods of characterizing the microphysical properties of ice clouds. Small shattered fragments result from the impact of natural ice crystals with the forward parts of aircraft-mounted measurement probes. The presence of these shattered fragments may result in a significant overestimation of the measured concentration of small ice crystals, contaminating the measurement of the ice particle size distribution (PSD). One method of identifying shattered particles is to use an inter-arrival time algorithm. This method is based on the assumption that shattered fragments form spatial clusters that have short inter-arrival times between particles, relative to natural particles, when they pass through the sample volume of the probe. The inter-arrival time algorithm is a successful technique for the classification of shattering artifacts and natural particles. This study assesses the limitations and efficiency of the inter-arrival time algorithm. The analysis has been performed using simultaneous measurements of two-dimensional (2-D) optical array probes with the standard and antishattering "K-tips" collected during the Airborne Icing Instrumentation Experiment (AIIE). It is shown that the efficiency of the algorithm depends on ice particle size, concentration and habit. Additional numerical simulations indicate that the effectiveness of the inter-arrival time algorithm to eliminate shattering artifacts can be significantly restricted in some cases. Improvements to the inter-arrival time algorithm are discussed. It is demonstrated that blind application of the inter-arrival time algorithm cannot filter out all shattered aggregates. To mitigate against the effects of shattering, the inter-arrival time algorithm should be used together with other means, such as antishattering tips and specially designed algorithms for segregation of shattered artifacts and natural particles.

The Microphysics of Ice and Precipitation Development in Tropical Cumulus Clouds

2015 ◽  
Vol 72 (6) ◽  
pp. 2429-2445 ◽  
Author(s):  
R. Paul Lawson ◽  
Sarah Woods ◽  
Hugh Morrison
Keyword(s):  
High Speed ◽  
Cloud Model ◽  
Supercooled Liquid ◽  
High Speed Photography ◽  
Cumulus Clouds ◽  
Cloud Particle ◽  
Ice Particles ◽  
Aircraft Observations ◽  
Bin Microphysics ◽  
Ice Production

Abstract The rapid glaciation of tropical cumulus clouds has been an enigma and has been debated in the literature for over 60 years. Possible mechanisms responsible for the rapid freezing have been postulated, but until now direct evidence has been lacking. Recent high-speed photography of electrostatically suspended supercooled drops in the laboratory has shown that freezing events produce small secondary ice particles. Aircraft observations from the Ice in Clouds Experiment–Tropical (ICE-T), strongly suggest that the drop-freezing secondary ice production mechanism is operating in strong, tropical cumulus updraft cores. The result is the production of small ice particles colliding with large supercooled drops (hundreds of microns up to millimeters in diameter), producing a cascading process that results in rapid glaciation of water drops in the updraft. The process was analyzed from data collected using state-of-the-art cloud particle probes during 54 Learjet penetrations of strong cumulus updraft cores over open ocean in a temperature range from 5° to −20°C. Repeated Learjet penetrations of an updraft core containing 3–5 g m−3 supercooled liquid showed an order-of-magnitude decrease in liquid mass concentration 3 min later at an elevation 1–1.5 km higher in the cloud. The aircraft observations were simulated using a one-dimensional cloud model with explicit bin microphysics. The model was initialized with drop and ice particle size distributions observed prior to rapid glaciation. Simulations show that the model can explain the observed rapid glaciation by the drop-freezing secondary ice production process and subsequent riming, which results when large supercooled drops collide with ice particles.

scholarly journals Assessment of performance of the inter-arrival time algorithm to identify ice shattering artifacts in cloud particle probes measurements

2014 ◽  
Vol 7 (10) ◽  
pp. 10249-10292 ◽  
Author(s):  
A. Korolev ◽  
P. R. Field
Keyword(s):  
Particle Size ◽  
Time Algorithm ◽  
Sample Volume ◽  
Ice Crystals ◽  
Interarrival Time ◽  
Cloud Particle ◽  
Measured Concentration ◽  
Microphysical Properties ◽  
Pass Through ◽  
The Impact

Abstract. Shattering presents a serious obstacle to current airborne in-situ methods of characterizing the microphysical properties of ice clouds. Small shattered fragments result from the impact of natural ice crystals with the forward parts of aircraft-mounted measurement probes. The presence of these shattered fragments may result in a significant overestimation of the measured concentration of small ice crystals, contaminating the measurement of the ice particle size distribution (PSD). One method of identifying shattered particles is to use an interarrival time algorithm. This method is based on the assumption that shattered fragments form spatial clusters that have short interarrival times between particles, relative to natural particles, when they pass through the sample volume of the probe. The interarrival time algorithm is a successful technique for the classification of shattering artifacts and natural particles. This study assesses the limitations and efficiency of the interarrival time algorithm. The analysis has been performed using simultaneous measurements of 2-D optical array probes with the standard and antishattering "K-tips" collected during the Airborne Icing Instrumentation Experiment (AIIE). It is shown that the efficiency of the algorithm depends on ice particle size, concentration and habit. Additional numerical simulations indicate that the effectiveness of the interarrival time algorithm to eliminate shattering artifacts can be significantly restricted in some cases. Improvements to the interarrival time algorithm are discussed.

In Situ Observations of the Microphysical Properties of Wave, Cirrus, and Anvil Clouds. Part II: Cirrus Clouds

2006 ◽  
Vol 63 (12) ◽  
pp. 3186-3203 ◽  
Author(s):  
R. Paul Lawson ◽  
Brad Baker ◽  
Bryan Pilson ◽  
Qixu Mo
Keyword(s):  
Particle Size ◽  
Number Concentration ◽  
Cirrus Clouds ◽  
Average Particle ◽  
Cloud Particle ◽  
Microphysical Properties ◽  
Irregular Shapes ◽  
Ice Particles ◽  
Research Aircraft ◽  
Particle Size And Shape

A Learjet research aircraft was used to collect microphysical data, including cloud particle imager (CPI) measurements of ice particle size and shape, in 22 midlatitude cirrus clouds. The dataset was collected while the aircraft flew 104 horizontal legs, totaling over 15 000 km in clouds. Cloud temperatures ranged from −28° to −61°C. The measurements show that cirrus particle size distributions are mostly bimodal, displaying a maximum in number concentration, area, and mass near 30 μm and another smaller maximum near 200–300 μm. CPI images show that particles with rosette shapes, which include mixed-habit rosettes and platelike polycrystals, constitute over 50% of the surface area and mass of ice particles >50 μm in cirrus clouds. Approximately 40% of the remaining mass of ice particles >50 μm are found in irregular shapes, with a few percent each in columns and spheroidal shapes. Plates account for <1% of the total mass. Particles <50 μm account for 99% of the total number concentration, 69% of the shortwave extinction, and 40% of the mass in midlatitude cirrus. Plots and average equations for area versus particle size are shown for various particle habits, and can be used in studies involving radiative transfer. The average particle concentration in midlatitude cirrus is on the order of 1 cm−3 with occasional 10-km averages exceeding 5 cm−3. There is a strong similarity of microphysical properties of ice particles between wave clouds and cirrus clouds, suggesting that, like wave clouds, cirrus ice particles first experience conversion to liquid water and/or solution drops before freezing.

Optimization of Solid Lipid Nanoparticles of Ezetimibe in Combination with Simvastatin Using Quality by Design (QbD)

2020 ◽  
Vol 10 (4) ◽  
pp. 404-418
Author(s):  
Kruti Borderwala ◽  
Ganesh Swain ◽  
Namrata Mange ◽  
Jaimini Gandhi ◽  
Manisha Lalan ◽  
...  
Keyword(s):  
Particle Size ◽  
Solid Lipid Nanoparticles ◽  
High Speed ◽  
Entrapment Efficiency ◽  
Lipid Nanoparticles ◽  
Water Soluble ◽  
Lipid Matrix ◽  
Solid Lipid ◽  
32 Factorial Design ◽  
Full Factorial Experimental Design

Background: The objective of this study was to develop solid lipid nanoparticles (SLNs) of poorly water soluble anti-hyperlipidemic drugs-Ezetimibe in combination with Simvastatin. Methods: This study describes a 32 full factorial experimental design to optimize the formulation of drug loaded lipid nanoparticles (SLN) by the high speed homogenization technique. The independent variables amount of lipid (GMS) and amount of surfactant (Poloxamer 188) were studied at three levels and arranged in a 32 factorial design to study the influence on the response variables- particle size, % entrapment efficiency (%EE) and cumulative drug release (% CDR) at 24 h. Results: The particle size, % EE and % CDR at 24 h for the 9 batches (B1 to B9) showed a wide variation of 104.6-496.6 nm, 47.80-82.05% (Simvastatin); 48.60-84.23% (Ezetimibe) and 54.64-92.27% (Simvastatin); 43.8-97.1% (Ezetimibe), respectively. The responses of the design were analysed using Design Expert 10.0.2. (Stat-Ease, Inc, USA), and the analytical tools of software were used to draw response surface plots. From the statistical analysis of data, polynomial equations were generated. Optimized formulation showed particle size of 169.5 nm, % EE of 75.43% (Simvastatin); 79.10% (Ezetimibe) and 74.13% (Simvastatin); 77.11% (Ezetimibe) %CDR after 24 h. Thermal analysis of prepared solid lipid nanoparticles gave indication of solubilisation of drugs within lipid matrix. Conclusion: Fourier Transformation Infrared Spectroscopy (FTIR) showed the absence of new bands for loaded solid lipid nanoparticles indicating no interaction between drugs and lipid matrix and being only dissolved in it. Electron microscope of transmission techniques indicated sphere form of prepared solid lipid nanoparticles with smooth surface with size approximately around 100 nm.

scholarly journals Splatters and Aerosols Contamination in Dental Aerosol Generating Procedures

2021 ◽  
Vol 11 (4) ◽  
pp. 1914
Author(s):  
Pingping Han ◽  
Honghui Li ◽  
Laurence J. Walsh ◽  
Sašo Ivanovski
Keyword(s):  
Particle Size ◽  
Disease Transmission ◽  
High Speed ◽  
Low Speed ◽  
Dental Procedures ◽  
Dental Equipment ◽  
Produce Contamination ◽  
Fluorescein Dye ◽  
Filter Papers ◽  
Airborne Disease

Dental aerosol-generating procedures produce a large amount of splatters and aerosols that create a major concern for airborne disease transmission, such as COVID-19. This study established a method to visualise splatter and aerosol contamination by common dental instrumentation, namely ultrasonic scaling, air-water spray, high-speed and low-speed handpieces. Mock dental procedures were performed on a mannequin model, containing teeth in a typodont and a phantom head, using irrigation water containing fluorescein dye as a tracer. Filter papers were placed in 10 different locations to collect splatters and aerosols, at distances ranging from 20 to 120 cm from the source. All four types of dental equipment produced contamination from splatters and aerosols. At 120 cm away from the source, the high-speed handpiece generated the greatest amount and size (656 ± 551 μm) of splatter particles, while the triplex syringe generated the largest amount of aerosols (particle size: 1.73 ± 2.23 μm). Of note, the low-speed handpiece produced the least amount and size (260 ± 142 μm) of splatter particles and the least amount of aerosols (particle size: 4.47 ± 5.92 μm) at 120 cm. All four dental AGPs produce contamination from droplets and aerosols, with different patterns of distribution. This simple model provides a method to test various preventive strategies to reduce risks from splatter and aerosols.

scholarly journals Leaching Behaviour of Construction and Demolition Wastes and Recycled Aggregates: Statistical Analysis Applied to the Release of Contaminants

2021 ◽  
Vol 11 (14) ◽  
pp. 6265
Author(s):  
Alessandra Diotti ◽  
Giovanni Plizzari ◽  
Sabrina Sorlini
Keyword(s):  
Particle Size ◽  
Statistical Analysis ◽  
Raw Materials ◽  
Primary Source ◽  
Recycled Aggregates ◽  
Critical Parameters ◽  
Material Particle ◽  
Analysis Methodology ◽  
Construction And Demolition Wastes ◽  
Leaching Behaviour

Construction and demolition wastes represent a primary source of new alternative materials which, if properly recovered, can be used to replace virgin raw materials partially or totally. The distrust of end-users in the use of recycled aggregates is mainly due to the environmental performance of these materials. In particular, the release of pollutants into the surrounding environment appears to be the aspect of greatest concern. This is because these materials are characterized by a strong heterogeneity which can sometimes lead to contaminant releases above the legal limits for recovery. In this context, an analysis of the leaching behaviour of both CDWs and RAs was conducted by applying a statistical analysis methodology. Subsequently, to evaluate the influence of the particle size and the volumetric reduction of the material on the release of contaminants, several experimental leaching tests were carried out according to the UNI EN 12457-2 and UNI EN 12457-4 standards. The results obtained show that chromium, mercury, and COD are the most critical parameters for both CDWs and RAs. Moreover, the material particle size generally affects the release of contaminants (i.e., finer particles showed higher releases), while the crushing process does not always involve higher releases than the sieving process.

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