Cirrus Microphysical Properties and Air Motion Statistics Using Cloud Radar Doppler Moments. Part I: Algorithm Description

2006 ◽  
Vol 45 (12) ◽  
pp. 1690-1709 ◽  
Author(s):  
Min Deng ◽  
Gerald G. Mace
Keyword(s):  
Particle Size ◽  
Vertical Velocity ◽  
Sample Volume ◽  
Doppler Spectrum ◽  
Convolution Integral ◽  
Mean Particle Size ◽  
Microphysical Properties ◽  
Spectrum Width ◽  
The Mean ◽  
Air Motion

Abstract The first three moments of the millimeter-wavelength radar Doppler spectrum provide valuable information regarding both cloud properties and air motion. An algorithm using these Doppler radar moments is developed to retrieve cirrus microphysical properties and the mean air vertical motion and their errors. The observed Doppler spectrum results from the convolution of a quiet-air radar reflectivity spectrum with the turbulence probability density function. Instead of expressing the convolution integral in terms of the particle fall velocity as in past studies, herein the convolution integral is integrated over the air motion so that the mean vertical velocity within the sample volume can be explicitly solved. To avoid an ill-conditioned problem, the turbulence is considered as a parameter in the algorithm and predetermined from the Doppler spectrum width and radar reflectivity based on the observation that the spread of the particle size distribution in the velocity domain dominates the Doppler spectrum width measurement for most cirrus. It is also shown that the assumed single mode functional shapes cannot reliably represent significant bimodalities. Nevertheless, the IWC can be retrieved more reliably than can the mass mean particle size. Error analysis also shows that the retrieval algorithm results are very sensitive to the power-law relationships describing the ice particle mass and the terminal velocity in terms of the particle maximum length. It is estimated that the algorithm errors will be on the order of 35%, 85%, and ±20 cm s−1 for mass mean particle size, IWC, and sample volume mean air motion, respectively. Algorithm validation with in situ data demonstrates that the algorithm can determine the cloud microphysical properties and air mean vertical velocity within the predicted theoretical error bounds.

Effect of Ag addition in Sn on growth of SnTe compound during reaction between molten solder and tellurium

2010 ◽  
Vol 25 (2) ◽  
pp. 391-395 ◽  
Author(s):  
Chien-Neng Liao ◽  
Yen-Chun Huang
Keyword(s):  
Particle Size ◽  
Reaction Time ◽  
Electrical Properties ◽  
Bismuth Telluride ◽  
Molten Solder ◽  
Thermoelectric Modules ◽  
Ag Addition ◽  
Mean Particle Size ◽  
Mechanical And Electrical Properties ◽  
The Mean

SnTe is the most common compound formed at the bismuth telluride/metal soldered junction of thermoelectric modules. It affects the mechanical and electrical properties of the soldered junction. In the study we investigate the growth of SnTe compound during reaction between molten Sn–3.5Ag solder and tellurium at 250 °C. We found that the growth of SnTe is suppressed by Ag–Te bilayer compounds that block further reaction between liquid Sn and Te. With increasing reaction time, the SnTe morphology becomes rough as a result of coarsening of SnTe grains. The growth of SnTe grains follows the conservative ripening kinetics with the mean particle size proportional to one-third power of reaction time.

Microstructure and Thermodynamic Analysis of Graphene-Reinforced Coating Surface

2021 ◽  
Vol 1033 ◽  
pp. 56-60
Author(s):  
He Ping Liu ◽  
Heng Zhe Yang ◽  
Lang Lang Liu ◽  
Feng Er Sun ◽  
Xiao Min Yang ◽  
...  
Keyword(s):  
Particle Size ◽  
Thermodynamic Analysis ◽  
Induction Coil ◽  
Mean Particle Size ◽  
Substrate Distance ◽  
Cladding Layer ◽  
Coating Surface ◽  
The Mean ◽  
Graphene Content

The microstructure of coatings with different graphene content and the hardness of cladding layer under different distance between coil and samples were investigated. The results showed that with the increase of graphene, the mean particle size of the powder did not get significantly coarser. The defects and oxides were appeared in the cladding layer and graphene diffused into the substrate. Distance between induction coil and sample has great impact on the hardness of coating, the higher hardness was measured in the distance between 6-8cm. The thermodynamic analysis of coating nucleation was carried out.

Preparation of Nanocrystalline Fe2O3 Powder by Cryomilling with Liquid Nitrogen and its Magnetic Property

2020 ◽  
Vol 993 ◽  
pp. 806-810
Author(s):  
Zhi Wei Zhang ◽  
Bing Wei Luo ◽  
Hai Tao Zhou ◽  
Fen Wang
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Magnetic Property ◽  
Liquid Nitrogen ◽  
Room Temperature ◽  
Single Phase ◽  
Rapid Preparation ◽  
Mean Particle Size ◽  
Milling Temperature ◽  
The Mean

Rapid preparation of nanocrystalline γ-Fe2O3 powder with superparamagnetism was realized by cryomilling commercial Fe2O3 powder using liquid nitrogen. The effects of milling temperature and duration on the grain size, phase and microstructure of the nanocrystalline Fe2O3 powder were analyzed. Magnetic property of the nanocrystalline γ-Fe2O3 powder was also tested by magnetometer at room temperature. The results demonstrate that nanocrystalline γ-Fe2O3 powder with single phase can be prepared rapidly by cryomilling with liquid nitrogen. The mean particle size of γ-Fe2O3 powder can be reduced from 300 nm to 13 nm by cryomilling at −130 °C within 3 hours. The nanocrystalline γ-Fe2O3 powder shows superparamagnetism at room temperature.

Preparation and Research of Oil in Water Microemulsion

2020 ◽  
Vol 1001 ◽  
pp. 110-114
Author(s):  
Xiao Qi Chen ◽  
Meng Meng Zhou ◽  
Zheng Zheng Wang ◽  
Hai Jun Zhou ◽  
Shu Lan Yang ◽  
...  
Keyword(s):  
Particle Size ◽  
Constant Temperature ◽  
Polydispersity Index ◽  
Stable System ◽  
Mass Ratio ◽  
Drop Method ◽  
Mean Particle Size ◽  
Oil In Water ◽  
The Mean ◽  
The Stability

A series of oil in water (O/W) microemulsions were prepared through drop by drop method at constant temperature, taking Span80/Tween80 as a composite emulsifying system and Macol-52 as oil phase. Effects of the mass ratio of composite emulsifying system and oil/emulsifier ratio on the particle size were studied. Finally, the best technological conditions were selected and the stability of the microemulsion was also researched. Results showed that the most suitable Span80/Tween80 mass ratio was 1:1 and the oil/emulsifier ratio is 1:1. Under this condition, the mean particle size of the o/w microemulsion was 71.1 nm and the polydispersity index was 0.151. Moreover, the microemulsion maintain a bright and uniform stable system after 20minutes’ centrifugation at the speed of 4000r/min and the particle size increased slightly.

The State of Polydispersion of Hevea Latex. II.

1947 ◽  
Vol 20 (2) ◽  
pp. 409-415
Author(s):  
J. H. E. Hessels
Keyword(s):  
Particle Size ◽  
Surface Area ◽  
Degree Of Polymerization ◽  
The State ◽  
Rubber Industry ◽  
Mean Particle Size ◽  
Degree Of Dispersion ◽  
The Mean ◽  
In The Beginning

Abstract The influence of the degree of dispersion in latex on the composition and properties of the rubber was studied in detail by means of a series of latices, the mean particle size of which ranged from 1.1 to 0.15µ in diameter. These fractions were first obtained by centrifugation of preserved latex, and the degree of distribution was measured by photomicrographic analysis and by sedimentation. This method of fractionation yields latices and rubbers with compositions which differ widely. With decrease in the size of the particles, their surface area per unit of rubber increases, and the percentage of nonrubber components which is adsorbed irreversibly or which is dissolved in the serum increases greatly. On the contrary, the degree of polymerization decreases with decrease in the diameter of the particles. This may be explained by the fact that, in the beginning, the polymerization of the globules is relatively low, and that it progresses under the influence of a catalyst present in the serum. In brief, then, systematic dispersoidal analysis of Hevea latex is of prime importance in the plantation rubber industry.

Changes in the electronic structure of gold particles upon thiol adsorption as a function of the mean particle size

2006 ◽  
Vol 495 (1-2) ◽  
pp. 180-185 ◽  
Author(s):  
Michael Büttner ◽  
Helge Kröger ◽  
Inga Gerhards ◽  
Daniel Mathys ◽  
Peter Oelhafen
Keyword(s):  
Particle Size ◽  
Electronic Structure ◽  
Gold Particles ◽  
Mean Particle Size ◽  
The Mean

Low-Temperature Synthesis of Cordierite Using Magnesite

2014 ◽  
Vol 608 ◽  
pp. 122-126
Author(s):  
Jae Hwan Pee ◽  
Geun Hee Kim ◽  
Na Ri Lee ◽  
Hyung Tea Kim ◽  
Lada Punsukumtana
Keyword(s):  
Particle Size ◽  
Magnesium Content ◽  
Low Density ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis ◽  
Mean Particle Size ◽  
Synthetic Rate ◽  
Low Thermal Expansion ◽  
Wide Range ◽  
The Mean

Cordierite (2MgO·2Al2O3·5SiO2) has a low density of 2.2 g/cm3 due to its high magnesium content. Because of its low thermal expansion coefficient of 1~2 x10-6 /°C, many studies are being conducted on the synthesis of cordierite with the expensive petalite as a replacement for lithium alumina silicate-based heat-resistant materials. The cordierite can be synthesized over a wide range: SiO2 at 50~70%, Al2O3 at 20~40%, and MgO at 10~30%. In this study, the range of chemical composition and temperature of cordierite synthesis is thoroughly investigated. In particular, we use natural materials (magnesite, kaolin and clay) to examine how thermal properties are affected by changes in crystal phase arising from the varying composition of MgO, SiO2 and Al2O3. We focused on factors leading to an increase in the rate of cordierite synthesis at temperatures below 1280 °C. From observing the synthetic rate over 1250~1280 °C, the sintered body at 1280 °C had a high synthetic rate greater than 80%. Magnesite was ball milled at constant intervals, and mean particle size was controlled to improve the synthetic rate of cordierite. As a result, the cordierite synthetic rate increased by more than 15% with decreasing the mean particle size of magnesite.

Preparation of Metal Nanosuspensions by High-Pressure DC-Sputtering on Running Liquids

1996 ◽  
Vol 457 ◽  
Author(s):  
M. Wagener ◽  
B. S. Murty ◽  
B. Günther
Keyword(s):  
Particle Size ◽  
High Pressure ◽  
Particle Size Distribution ◽  
Pressure Range ◽  
Narrow Particle Size Distribution ◽  
Descriptive Model ◽  
Mean Particle Size ◽  
Dc Sputtering ◽  
The Mean ◽  
Argon Sputtering

ABSTRACTA modified VERL-process (Vacuum evaporation on running liquids) employing high pressure magnetron sputtering has been used for the preparation of suspensions with metal nanoparticles. The method has been tested for Ag- and Fe-suspensions by varying the pressure of the Argon sputtering atmosphere in the range of 1 to 30 Pa. A narrow particle size distribution with a mean particle size ranging from 5–18 nm has been found. The mean particle size increases with increasing Argon pressure in the pressure range under investigation. A descriptive model for the process of particle formation as a function of sputtering gas pressure is given.

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