scholarly journals Nanoparticle coagulation and dispersion in a turbulent planar jet with constraints

2012 ◽  
Vol 16 (5) ◽  
pp. 1497-1501 ◽  
Author(s):  
Cheng-Xu Tu ◽  
Song Liu
Keyword(s):  
Standard Deviation ◽  
Dynamic Equation ◽  
Moment Method ◽  
Particle Diameter ◽  
Geometric Standard Deviation ◽  
Spatiotemporal Evolution ◽  
Planar Jet ◽  
The Mean ◽  
Mean Particle Diameter ◽  
General Dynamic

Numerical simulations of coagulating and dispersing nanoparticles in an incompressible turbulent planar jet with constraints are performed. The evolution of nanoparticle field is obtained by utilizing a moment method to approximate the particle's general dynamic equation. The spatiotemporal evolution of the first three moments along with the mean particle diameter and geometric standard deviation of particle diameter are discussed

Prediction of the deflagration index for organic dusts as a function of the mean particle diameter

2017 ◽  
Vol 50 ◽  
pp. 67-74 ◽  
Author(s):  
Anna Fumagalli ◽  
Marco Derudi ◽  
Renato Rota ◽  
Jef Snoeys ◽  
Sabrina Copelli
Keyword(s):  
Particle Diameter ◽  
Deflagration Index ◽  
The Mean ◽  
Mean Particle Diameter

scholarly journals Retrospection of Anti–Blood Group Antibody Proficiency Testing Data Using the Geometric Mean and Standard Deviation

2019 ◽  
Vol 153 (4) ◽  
pp. 530-536 ◽  
Author(s):  
John Jeongseok Yang ◽  
Yousun Chung ◽  
Hyungsuk Kim ◽  
Dae-Hyun Ko ◽  
Sang-Hyun Hwang ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Blood Group ◽  
Proficiency Testing ◽  
Geometric Mean ◽  
Geometric Standard Deviation ◽  
Geometric Means ◽  
Consensus Criterion ◽  
Mode 2 ◽  
Testing Data ◽  
The Mean

Abstract Objectives We reanalyzed the data from proficiency testing (PT) to assess the effect of the geometric mean in the statistical analysis of immunohematologic data. Methods Using the five most recent anti–blood group antibody titer participant summary results, the geometric mean (GM) ±2 × geometric standard deviation (GSD) was used as the comparative consensus criterion to mode ±2 titers. Results Using the PT evaluation criterion of mode ±2 titers, the mean percentages of participants with acceptable results were 97.5% and 97.8% for anti-A and anti-D, respectively. When applying GM ±2 GSD, the mean percentages of acceptable results were 96.1% (anti-A) and 96.1% (anti-D). The percentages of responses included in each consensus criterion were lower using GM ±2 GSD, with a few exceptions. Conclusions Geometric means are more robust and precise in visualizing the central tendency. This method can improve the statistical robustness of PT evaluations.

Influence of nucleating agent type on the morphology of extruded polyetherimide foam for printed circuit boards*

2019 ◽  
Vol 56 (3) ◽  
pp. 317-341 ◽  
Author(s):  
Clemens Keilholz ◽  
Daniel Raps ◽  
Thomas Köppl ◽  
Volker Altstädt
Keyword(s):  
Surface Tension ◽  
Printed Circuit Boards ◽  
Particle Diameter ◽  
Nucleating Agent ◽  
Nucleating Agents ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Foam Morphology ◽  
The Mean ◽  
Mean Particle Diameter

This work focuses on the development of foamed high temperature thermoplastic substrates for printed circuit boards. For this application it is necessary to achieve mean cell diameters smaller than 30 µm in order to be able to realize vias and high packaging densities (miniaturization). Different additives as nucleating agents, namely macro- and micro-crystalline talc, silica, calcium carbonate, and wollastonite, were melt-compounded with polyetherimide using a twin-screw extruder. Foamed samples are prepared by foam extrusion using a slit die and CO2 as physical blowing agent. The aim of this study is to analyze the influence of the mean particle size and the particle surface tension on the mean cell diameters. Therefore, the shape of the additives, the foam morphology, and the elongational viscosity were considered. The additives with a suitable particle size and surface tension exhibit a positive influence on the foam morphology, resulting in smaller cell diameters (<30 µm), a narrower cell size distribution and a foam density lower than 900 kg/m3. If the mean particle diameter of the nucleating agents is lower than 0.6 µm in this study, no nucleation effect could be observed. This is related to the fact that no heterogeneous nucleation occurs, if the particle diameter is too small. If the mean particle diameter of the used additives is larger than 1.5 µm, which could be demonstrated in this study in case of polyetherimide, then the additive acts as nucleating agent and heterogeneous nucleation occurs. Furthermore, it was observed that the mean cell diameter was affected by the different surface tensions of the studied nucleating agents.

scholarly journals The role of mixing layer on changes of particle properties in lower troposphere

2009 ◽  
Vol 9 (4) ◽  
pp. 16483-16525
Author(s):  
L. Ferrero ◽  
E. Bolzacchini ◽  
M. G. Perrone ◽  
S. Petraccone ◽  
G. Sangiorgi ◽  
...  
Keyword(s):  
Size Distribution ◽  
Mixing Layer ◽  
Particle Diameter ◽  
Lower Troposphere ◽  
Atmospheric Particulate Matter ◽  
Vertical Profiles ◽  
Stable Conditions ◽  
The Mean ◽  
Hierarchical Statistical Model ◽  
Mean Particle Diameter

Abstract. Vertical profiles of atmospheric particulate matter number concentration, size distribution and chemical composition were directly measured in the city of Milan, over three years (2005–2008) of field campaigns. An optical particle counter, a portable meteorological station and a miniaturized cascade impactor were deployed on a tethered balloon. Mixing layer height was estimated by PM dispersion along height. More than 300 PM vertical profiles were measured both in the winter and summer, mainly in clear and dry sky conditions. Under these conditions, no significant changes in NO3−, SO42− or NH4+ into or over the mixing layer were found. From experimental measurements we observed changes in size distribution along height. An increase of the mean particle diameter, in the accumulation mode, passing through the mixing layer under stable conditions was highlighted; the mean relative growth was 2.1±0.1% in the winter and 3.9±0.3% in the summer. At the same time, sedimentation processes occurred across the ML height for coarse particles leading to a mean particle diameter reduction (14.9±0.6% in the winter and 10.7±1.0% in summer). A hierarchical statistical model for the PM size distribution has been developed to describe the aging process of the finest PM fraction along height. The proposed model is able to estimate the typical vertical profile that characterises launches within pre-specified groups. The mean growth estimated on the basis of the model was 1.9±0.5% in the winter and 6.1±1.2% in the summer, in accordance with experimental evidence.

scholarly journals Inverse modeling of cloud-aerosol interactions – Part 2: Sensitivity tests on liquid phase clouds using a Markov Chain Monte Carlo based simulation approach

2011 ◽  
Vol 11 (7) ◽  
pp. 20051-20105 ◽  
Author(s):  
D. G. Partridge ◽  
J. A. Vrugt ◽  
P. Tunved ◽  
A. M. L. Ekman ◽  
H. Struthers ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Markov Chain ◽  
Markov Chain Monte Carlo ◽  
Standard Deviation ◽  
Mass Fraction ◽  
Cloud Model ◽  
Number Concentration ◽  
Geometric Standard Deviation ◽  
Accumulation Mode ◽  
The Mean

Abstract. This paper presents a novel approach to investigate cloud-aerosol interactions by coupling a Markov Chain Monte Carlo (MCMC) algorithm to a pseudo-adiabatic cloud parcel model. Despite the number of numerical cloud-aerosol sensitivity studies previously conducted few have used statistical analysis tools to investigate the sensitivity of a cloud model to input aerosol physiochemical parameters. Using synthetic data as observed values of cloud droplet number concentration (CDNC) distribution, this inverse modelling framework is shown to successfully converge to the correct calibration parameters. The employed analysis method provides a new, integrative framework to evaluate the sensitivity of the derived CDNC distribution to the input parameters describing the lognormal properties of the accumulation mode and the particle chemistry. To a large extent, results from prior studies are confirmed, but the present study also provides some additional insightful findings. There is a clear transition from very clean marine Arctic conditions where the aerosol parameters representing the mean radius and geometric standard deviation of the accumulation mode are found to be most important for determining the CDNC distribution to very polluted continental environments (aerosol concentration in the accumulation mode >1000 cm−3) where particle chemistry is more important than both number concentration and size of the accumulation mode. The competition and compensation between the cloud model input parameters illustrate that if the soluble mass fraction is reduced, both the number of particles and geometric standard deviation must increase and the mean radius of the accumulation mode must increase in order to achieve the same CDNC distribution. For more polluted aerosol conditions, with a reduction in soluble mass fraction the parameter correlation becomes weaker and more non-linear over the range of possible solutions (indicative of the sensitivity). This indicates that for the cloud parcel model used herein, the relative importance of the soluble mass fraction appears to decrease if the number or geometric standard deviation of the accumulation mode is increased. This study demonstrates that inverse modelling provides a flexible, transparent and integrative method for efficiently exploring cloud-aerosol interactions efficiently with respect to parameter sensitivity and correlation.

Number concentration dependence of ultrasonic disruption ratio of diameter-sorted microcapsules

2022 ◽  
pp. 095441192110703
Author(s):  
Junsyou Kanashima ◽  
Naohiro Sugita ◽  
Tadahiko Shinshi
Keyword(s):  
Drug Delivery Systems ◽  
Focused Ultrasound ◽  
Particle Number ◽  
Particle Diameter ◽  
Number Concentration ◽  
The Mean ◽  
And Control ◽  
Polymer Shells ◽  
Filtration Technique ◽  
Mean Particle Diameter

The use of ultrasound to destroy microcapsules in microbubble-assisted drug delivery systems (DDS) is of great interest. In the present study, the disruption ratios of capsule clusters were measured by observing and experimentally analyzing microcapsules with polymer shells undergoing disruption by ultrasound. The microcapsules were dispersed in a planar microchamber filled with a gelatin gel and sonicated using 1 MHz focused ultrasound. Different capsule populations were obtained using a filtration technique to modify and control the capsule sizes. The disruption ratio as a function of the concentration of capsules was obtained through image processing of the recorded photomicrographs. We found that the disruption ratio for each population exponentially decreases as the particle number concentration (PNC) increases. The maximum disruption ratio of the diameter-sorted capsules was larger than that of polydispersed capsules. Particularly, for resonant capsule populations, the ratio was more than twice that of polydispersed capsules. Furthermore, the maximum disruption ratio occurred at higher concentrations as the mean particle diameter of the capsule cluster decreased.

Experimental Study of Water and Air Based Permeabilities of Washed and Screened Sands

2005 ◽  
Author(s):  
Shu-Ye Lei
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Porous Media ◽  
Particle Diameter ◽  
Velocity Slip ◽  
Slip Effect ◽  
Slip Effects ◽  
Water Based ◽  
The Mean ◽  
Mean Particle Diameter

The permeability of narrow screened washed sands of granularity 100–450 μm was measured experimentally using water and air to investigate the effect of slip on the gas based permeability. The experimental data show that the air based permeability of the unconsolidated particle media is not proportional to the square of the mean particle diameter and that slip significantly affects the air based permeability measurements for unconsolidated porous media. The velocity slip effect is significant even for Kn&lt;10−3. Slip effects were not found in the water based permeability measurements with the same sand samples. All of the experimental data lay around the curve k/d=0.283φ2.67 within ± 4.1%. However, the water based permeability was not below all of the air based permeability as expected. The air based permeability eliminated slip effects was about 59 % lower than that water based one, much larger than possible measurement. The experimental results showed that the standard air viscosity value in the handbooks was not its actual, the actual air viscosity may be over twice of that in handbooks.

Aerosol Synthesis of Aluminum Nitride Powders

1991 ◽  
Vol 249 ◽  
Author(s):  
Albert A. Adjaottor ◽  
Gregory L. Griffin
Keyword(s):  
Particle Size ◽  
Residence Time ◽  
Particle Diameter ◽  
Aerosol Formation ◽  
Yield Efficiency ◽  
Operating Variables ◽  
Aerosol Process ◽  
The Mean ◽  
Diffusive Mixing ◽  
Mean Particle Diameter

ABSTRACTWe describe a new laboratory-scale aerosol process for producing AIN powder. A two-stage reactor design is used. In the first stage, triethyl aluminum (TEA = AI(CC2H5 )3) and NH3 react to form an aerosol adduct in a laminar flow diffusive mixing zone. The aerosol then enters the furnace stage, where it is converted to AIN. We have examined the influence of the major operating variables (e.g., inlet TEA concentration, reactor residence time, and furnace temperature) on the particle size and distribution, yield, and efficiency. For example, increasing the TEA concentration from 0.12 to 1.30 µmol/cm3 causes an increase in the mean particle diameter (from 0.07 to 0.13 Pim), a slight increase in polydispersity (from 0.31 to 0.43), and a decrease in yield efficiency (from 90% to 73%). In contrast, decreasing the reactor residence time (by increasing the flow rate) has little effect on mean particle diameter, but causes a significant increase in yield efficiency (approaching 100%). The overall behavior of the reactor suggests a model in which the particle size distribution of the final product is determined primarily by the aerosol formation steps in the mixing stage (i.e., nucleation, growth, and coalescence), while the composition and crystallinity of the product are determined by furnace conditions.

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