Enable a Facile Size Re-distribution of MBE-Grown Ga-Droplets via In Situ Pulsed Laser Shooting

AbstractA MBE-prepared Gallium (Ga)-droplet surface on GaAs (001) substrate is in situ irradiated by a single shot of UV pulsed laser. It demonstrates that laser shooting can facilely re-adjust the size of Ga-droplet and a special Ga-droplet of extremely broad size-distribution with width from 16 to 230 nm and height from 1 to 42 nm are successfully obtained. Due to the energetic inhomogeneity across the laser spot, the modification of droplet as a function of irradiation intensity (IRIT) can be straightly investigated on one sample and the correlated mechanisms are clarified. Systematically, the laser resizing can be perceived as: for low irradiation level, laser heating only expands droplets to make mergences among them, so in this stage, the droplet size distribution is solely shifted to the large side; for high irradiation level, laser irradiation not only causes thermal expansion but also thermal evaporation of Ga atom which makes the size-shift move to both sides. All of these size-shifts on Ga-droplets can be strongly controlled by applying different laser IRIT that enables a more designable droplet epitaxy in the future.

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Evaluating Chemical Dispersant Efficacy in an Experimental Wave Tank: 2—Significant Factors Determining In Situ Oil Droplet Size Distribution

Environmental Engineering Science ◽

10.1089/ees.2008.0408 ◽

2009 ◽

Vol 26 (9) ◽

pp. 1407-1418 ◽

Cited By ~ 34

Author(s):

Zhengkai Li ◽

Kenneth Lee ◽

Thomas King ◽

Michel C. Boufadel ◽

Albert D. Venosa

Keyword(s):

Size Distribution ◽

Droplet Size ◽

Droplet Size Distribution ◽

Wave Tank ◽

Oil Droplet ◽

Chemical Dispersant ◽

Oil Droplet Size ◽

Significant Factors

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Evaluating MODIS cloud retrievals with in situ observations from VOCALS-REx

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-23679-2012 ◽

2012 ◽

Vol 12 (9) ◽

pp. 23679-23729 ◽

Cited By ~ 1

Author(s):

N. J. King ◽

K. N. Bower ◽

J. Crosier ◽

I. Crawford

Keyword(s):

Size Distribution ◽

Droplet Size ◽

Liquid Water ◽

Near Infrared ◽

Droplet Size Distribution ◽

Effective Radius ◽

Liquid Water Path ◽

Water Path ◽

High Bias

Abstract. Microphysical measurements collected during eleven profiles through marine stratocumulus as part of the Variability of the American Monsoon Systems (VAMOS) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) are compared to collocated overpasses of the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua and Terra satellite platforms. The full depth of the cloud is sampled in each case using a Cloud Droplet Probe (CDP) and a Two-Dimensional Stereo Probe (2DS) together sizing cloud and precipitation droplets in the diameter range 2-1260 μm. This allows the total optical depth (τc) of the cloud and effective radius (re) of the droplet size distribution to be compared to MODIS cloud retrievals of the same quantities along with the secondarily derived total liquid water path. When compared to the effective radius at cloud top, the MODIS retrieved re using the 2.1 μm wavelength channel overestimates the in situ measurements on average by 13% with the largest overestimations coinciding with the detection by the 2DS of drizzle sized droplets. We show through consideration of the full vertical profile and penetration depths of the wavelengths used in the retrieval that the expected retrieved values are less than those at cloud top thus increasing the apparent bias in re retrievals particularly when using the 1.6 and 2.1 μm channels, with the 3.7 μm channel retrievals displaying the best agreement with in situ values. Retrievals of τc also tend to overestimate in situ values which, coupled with a high bias in re retrievals, lead to an overestimation of liquid water path. There is little apparent correlation between the variation of the three near-infrared re retrievals and the vertical structure of the cloud observed in situ. Retrievals are performed using measured profiles of water vapour and temperature along with an accurate knowledge of the width of the droplet size distribution which improve agreement between in situ and retrieved values but cannot completely explain the observed biases. Additionally we show that cloud heterogeneity and three-dimensional radiative effects may high skew the mean when averaging over comparison domains but cannot explain all of the apparent high bias.

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In-situ Tests and Analysis for Droplet Size Distribution on the Clean Flue of Coal-fired Power Plant

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/450/1/012042 ◽

2020 ◽

Vol 450 ◽

pp. 012042

Author(s):

Zonghui Li ◽

Wenguang Cao ◽

Xiu Liu ◽

Jun Chen ◽

Cuijia Duan

Keyword(s):

Power Plant ◽

Size Distribution ◽

Droplet Size ◽

Droplet Size Distribution ◽

In Situ Tests

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Oil plume simulations: Tracking oil droplet size distribution and fluorescence within high-pressure release jets

International Oil Spill Conference Proceedings ◽

10.7901/2169-3358-2017.1.1230 ◽

2017 ◽

Vol 2017 (1) ◽

pp. 1230-1250

Author(s):

R.N. Conmy ◽

B. Robinson ◽

T. King ◽

M. Boufadel ◽

S. Ryan ◽

...

Keyword(s):

Water Temperature ◽

Size Distribution ◽

Droplet Size ◽

Oil Spill ◽

Droplet Diameter ◽

Performance Testing ◽

Droplet Size Distribution ◽

Optical Measurements ◽

Total Petroleum Hydrocarbons

ABSTRACT Optical measurements have been used during oil spill response for more than three decades to determine oil presence in slicks and plumes. Oil surveillance approaches range from simple (human eyeball) to the sophisticated (sensors on AUVs, aircraft, satellites). In situ fluorometers and particle size analyzers were deployed during the Deepwater Horizon (DWH) Gulf of Mexico oil spill to track shallow and deep subsea plumes. Uncertainties regarding instrument specifications and capabilities during DWH necessitated performance testing of sensors exposed to simulated, dispersed oil plumes. Seventy-two wave tank experiments were conducted at the Bedford Institute of Oceanography. Simulated were oil releases with varying parameters such as oil release rate, oil temperature (reservoir temp ~ 80 °C), water temperature (<8 °C and >15 °C), oil type, dispersant type (Corexit 9500 and Finasol OSR52) and dispersant to oil ratio (DOR). Plumes of Alaskan North Slope Crude (ANS), South Louisiana Crude (SLC) and IFO-120 oils were tracked using in situ fluorescence, droplet size distribution (DSD), total petroleum hydrocarbons (TPH) and benzene-toluene-ethylbenzene-xylene (BTEX). For the lighter SLC, bimodal droplet size with mean diameter < 70 μm was achieved for 1:20 and 1:100 DOR, regardless of water temperature. Similarly, the medium ANS crude exhibited mean droplet diameter <70 μm, but was bimodal only for the 1:20 treatment. Bimodal distribution was not achieved with the heavy IFO, but droplet < 70 μm were observed for 1:20 warm waters, indicating poor dispersibility of the high viscosity oil even for jet releases. Results offer valuable information on the behavior and dispersibility of oils over a range of viscosity, DOR and environmental conditions. Findings have implications for fate and transport models, where DSD, chemistry and fluorescence are all impacted by release variables. This research was supported by the Bureau of Safety and Environmental Enforcement.

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Evaluating MODIS cloud retrievals with in situ observations from VOCALS-REx

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-191-2013 ◽

2013 ◽

Vol 13 (1) ◽

pp. 191-209 ◽

Cited By ~ 38

Author(s):

N. J. King ◽

K. N. Bower ◽

J. Crosier ◽

I. Crawford

Keyword(s):

Size Distribution ◽

Droplet Size ◽

Liquid Water ◽

Droplet Size Distribution ◽

Effective Radius ◽

Liquid Water Path ◽

Water Path ◽

High Bias ◽

In Situ Observations

Abstract. Microphysical measurements collected during eleven profiles, by the UK BAe-146 aircraft, through marine stratocumulus as part of the Variability of the American Monsoon Systems (VAMOS) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) are compared to collocated overpasses of the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua and Terra satellite platforms. The full depth of the cloud is sampled in each case using a Cloud Droplet Probe (CDP) and a Two-Dimensional Stereo Probe (2DS) together sizing cloud and precipitation droplets in the diameter range 2–1260 μm. This allows the total optical depth (τc) of the cloud and effective radius (re) of the droplet size distribution to be compared to MODIS cloud retrievals of the same quantities along with the secondarily derived total liquid water path. When compared to the effective radius at cloud top, the MODIS retrieved re using the 2.1 μm wavelength channel overestimates the in situ measurements on average by 13% with the largest overestimations coinciding with the detection by the 2DS of drizzle sized droplets. We show through consideration of the full vertical profile and penetration depths of the wavelengths used in the retrieval that the expected retrieved values are less than those at cloud top thus increasing the apparent bias in re retrievals particularly when using the 1.6 and 2.1 μm channels, with the 3.7 μm channel retrievals displaying the best agreement with in situ values. Retrievals of τc also tend to overestimate in situ values which, coupled with a high bias in re retrievals, lead to an overestimation of liquid water path. There is little apparent correlation between the variation of the three near-infrared re retrievals and the vertical structure of the cloud observed in situ. Retrievals are performed using measured profiles of water vapour and temperature along with an accurate knowledge of the width of the droplet size distribution which improve agreement between in situ and retrieved values but cannot completely explain the observed biases. Additionally we show that cloud heterogeneity and three-dimensional radiative effects may high skew the mean when averaging over comparison domains but cannot explain all of the apparent high bias. An intercomparison between in situ measurements from the BAe-146 and C-130 platforms is also presented, highlighting the uncertainties associated with in situ observations.

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