scholarly journals In Situ Observation of Cirrus Scattering Phase Functions with 22° and 46° Halos: Cloud Field Study on 19 February 1998

2001 ◽  
Vol 58 (22) ◽  
pp. 3376-3390 ◽  
Author(s):  
Frederique Auriol ◽  
Jean-François Gayet ◽  
Guy Febvre ◽  
Olivier Jourdan ◽  
Laurent Labonnote ◽  
...  
Keyword(s):  
Field Study ◽  
In Situ Observation ◽  
Scattering Phase ◽  
Phase Functions

Unobtrusive Observation of Cycling Tourists in the Wild

2014 ◽  
Vol 6 (4) ◽  
pp. 22-42
Author(s):  
Benjamin Poppinga ◽  
Martin Pielot ◽  
Wilko Heuten ◽  
Susanne Boll
Keyword(s):  
Field Study ◽  
In Situ Observation ◽  
In Situ Techniques ◽  
In The Wild ◽  
The Individual ◽  
Post Hoc ◽  
Real Challenge ◽  
Unobtrusive Observation

The observation of cycling tourists is a real challenge. Traditional in-situ observation techniques fail as they threaten the intimateness of the experience and often interfere with the users' tasks. In post-hoc studies, like interviews, participants are unable to recap all details of their earlier experience accurately. This paper investigates how a hybrid, i.e., in-situ and post-hoc, observation approach can overcome the individual limitations and thereby provide detailed insights without disturbing the cyclists. The authors demonstrate the approach in a field study, where we observed 11 tourists with three unobtrusive in-situ techniques and used the gathered data to jog their memories in a post-hoc interview. They found that the observation technique allows to get detailed and accurate insights, and the communication between experimenter and participant becomes clearer. The authors conclude that hybrid observation would be valuable in other mobile field study settings.

scholarly journals On the interpretation of an unusual in-situ measured ice crystal scattering phase function

2012 ◽  
Vol 12 (19) ◽  
pp. 9355-9364 ◽  
Author(s):  
A. J. Baran ◽  
J.-F. Gayet ◽  
V. Shcherbakov
Keyword(s):  
Phase Function ◽  
Asymmetry Parameter ◽  
Ice Crystals ◽  
Climate Modelling ◽  
Ice Crystal ◽  
Ice Particles ◽  
Scattering Phase ◽  
Scattering Phase Function ◽  
Phase Functions

Abstract. In-situ Polar Nephelometer (PN) measurements of unusual ice crystal scattering phase functions, obtained near the cloud-top of a mid-latitude anvil cloud, at a temperature of about −58 °C, were recently reported by Gayet et al. (2012). The ice crystal habits that produced the phase functions consisted of aggregates of ice crystals and aggregates of quasi-spherical ice particles. The diameters of the individual quasi-spherical ice particles were estimated to be between about 15 μm and 20 μm. The measured-averaged scattering phase functions were featureless, at scattering angles less than about 100°, but an ice bow-like feature was noted between the scattering angles of about 120° to 160°. The estimated asymmetry parameter was 0.78 ± 0.04. In this paper, the averaged scattering phase function is interpreted in terms of a weighted habit mixture model. The model that provides the best overall fit to the measured scattering phase function comprises of highly distorted ten-element hexagonal ice aggregates and quasi-spherical ice particles. The smaller quasi-spherical ice crystals are represented by Chebyshev ice particles of order 3, and were assumed to have equivalent spherical diameters of 24 μm. The asymmetry parameter of the best overall model was found to be 0.79. It is argued that the Chebyshev-like ice particles are responsible for the ice bow-like feature and mostly dominate the scattered intensity measured by the PN. The results from this paper have important implications for climate modelling (energy balance of anvils), cloud physics and the remote sensing of cirrus properties.

scholarly journals On the interpretation of an unusual in-situ measured ice crystal scattering phase function

2012 ◽  
Vol 12 (5) ◽  
pp. 12485-12502 ◽  
Author(s):  
A. J. Baran ◽  
J.-F. Gayet ◽  
V. Shcherbakov
Keyword(s):  
Phase Function ◽  
Asymmetry Parameter ◽  
Ice Crystals ◽  
Climate Modelling ◽  
Ice Crystal ◽  
Ice Particles ◽  
Scattering Phase ◽  
Scattering Phase Function ◽  
Phase Functions

Abstract. In-situ Polar Nephelometer (PN) measurements of unusual ice crystal scattering phase functions were recently reported by Gayet et al. (2012). The ice crystal habits that produced the phase functions were small chain-like aggregates, which had on their surfaces, smaller quasi-spherical ice crystals. The measured-averaged phase functions were featureless, at scattering angles less than about 100°, but an ice bow-like feature was noted between the scattering angles of about 120° to 160°. The estimated asymmetry parameter was 0.78 ± 0.04. In this paper, the phase function is interpreted in terms of a weighted habit mixture model. The best-fit model comprises of highly distorted ten element hexagonal ice aggregates, and the smaller quasi-spherical ice crystals are represented by Chebyshev ice particles. The weighted mean asymmetry parameter was found to be 0.81. It is argued that the Chebyshev-like ice particles are responsible for the ice bow-like feature and mostly dominate the scattered intensity measured by the PN. The results of this paper have important implications for climate modelling (energy balance of anvils) and the remote sensing of cirrus properties.

scholarly journals Optical properties of pristine ice crystals in mid-latitude cirrus clouds: a case study during CIRCLE-2 experiment

2010 ◽  
Vol 10 (10) ◽  
pp. 24763-24780
Author(s):  
J.-F. Gayet ◽  
G. Mioche ◽  
V. Shcherbakov ◽  
C. Gourbeyre ◽  
R. Busen ◽  
...  
Keyword(s):  
Ice Crystals ◽  
Careful Examination ◽  
Data Sets ◽  
Cloud Particle ◽  
Complex Shapes ◽  
Plate Shape ◽  
Scattering Phase ◽  
Scattering Phase Function ◽  
Phase Functions

Abstract. Preferential horizontally-oriented ice crystals with a prevalent hexagonal-plate shape revealed by the Cloud Particle Imager can explain systematic larger Lidar CALIOP extinctions when compared with extinction derived from co-located in situ measurements. Surprisingly, the Polar Nephelometer does not reveal any signature of 22° (and 46°) halos, showing a rather featureless scattering phase function in this case. In contrast, well pronounced 22° halo peaks are observed with predominant similar-shaped ice crystals in other cirrus situations. This paper discusses the results of a careful examination of CPI images with Polar Nephelometer observations in order to explain occurrence and non occurrence of the 22° halo feature. Observations highlight that halo peaks are evidenced only by the presence of perfect plate ice crystals (or pristine crystals). On the basis of previous data sets in mid-latitude cirrus it is found that simple pristine crystals are uncommon whereas particles with imperfect or complex shapes are prevalent. As a result, phase functions are smooth and featureless and best represent cirrus scattering properties.

In Situ Observation of Catalyzed Gasification of Graphite by Nickel

1981 ◽  
Vol 39 ◽  
pp. 76-77
Author(s):  
R. T. K. Baker ◽  
R. D. Sherwood
Keyword(s):  
Objective Lens ◽  
In Situ Observation ◽  
Gas Flows ◽  
Catalytic Gasification ◽  
Television Camera ◽  
Viewing Screen ◽  
Fuels And Chemicals ◽  
Gasification Of Carbon ◽  
Transmission Microscope

The catalytic gasification of carbon at high temperature by microscopic size metal particles is of fundamental importance to removal of coke deposits and conversion of refractory hydrocarbons into fuels and chemicals. The reaction of metal/carbon/gas systems can be observed by controlled atmosphere electron microscopy (CAEM) in an 100 KV conventional transmission microscope. In the JEOL gas reaction stage model AGl (Fig. 1) the specimen is positioned over a hole, 200μm diameter, in a platinum heater strip, and is interposed between two apertures, 75μm diameter. The control gas flows across the specimen and exits through these apertures into the specimen chamber. The gas is further confined by two apertures, one in the condenser and one in the objective lens pole pieces, and removed by an auxiliary vacuum pump. The reaction zone is <1 mm thick and is maintained at gas pressure up to 400 Torr and temperature up to 1300<C as measured by a Pt-Pt/Rh 13% thermocouple. Reaction events are observed and recorded on videotape by using a Philips phosphor-television camera located below a hole in the center of the viewing screen. The overall resolution is greater than 2.5 nm.

In situ observation of the martensitic transformation in (Mg,Y)-PSZ

1986 ◽  
Vol 44 ◽  
pp. 500-501
Author(s):  
R-R. Lee
Keyword(s):  
Martensitic Transformation ◽  
High Strength ◽  
Nucleation And Growth ◽  
In Situ Observation ◽  
Considerable Potential ◽  
Transmission Electron ◽  
Structural Applications ◽  
Applied Stresses ◽  
Kinetics Of

Partially-stabilized ZrO2 (PSZ) ceramics have considerable potential for advanced structural applications because of their high strength and toughness. These properties derive from small tetragonal ZrO2 (t-ZrO2) precipitates in a cubic (c) ZrO2 matrix, which transform martensitically to monoclinic (m) symmetry under applied stresses. The kinetics of the martensitic transformation is believed to be nucleation controlled and the nucleation is always stress induced. In situ observation of the martensitic transformation using transmission electron microscopy provides considerable information about the nucleation and growth aspects of the transformation.

In situ TEM observations of melting in nanosized eutectic Pb-Cd inclusions embedded in Al

1996 ◽  
Vol 54 ◽  
pp. 986-987
Author(s):  
S. Hagège ◽  
U. Dahmen ◽  
E. Johnson ◽  
A. Johansen ◽  
V.S. Tuboltsev
Keyword(s):  
Electron Microscope ◽  
Melt Spinning ◽  
Ternary Alloys ◽  
Solid Matrix ◽  
Eutectic System ◽  
In Situ Tem ◽  
In Situ Observation ◽  
Orientation Relationships ◽  
Transmission Electron

Small particles of a low-melting phase embedded in a solid matrix with a higher melting point offer the possibility of studying the mechanisms of melting and solidification directly by in-situ observation in a transmission electron microscope. Previous studies of Pb, Cd and other low-melting inclusions embedded in an Al matrix have shown well-defined orientation relationships, strongly faceted shapes, and an unusual size-dependent superheating before melting.[e.g. 1,2].In the present study we have examined the shapes and thermal behavior of eutectic Pb-Cd inclusions in Al. Pb and Cd form a simple eutectic system with each other, but both elements are insoluble in solid Al. Ternary alloys of Al (Pb,Cd) were prepared from high purity elements by melt spinning or by sequential ion implantation of the two alloying additions to achieve a total alloying addition of up to lat%. TEM observations were made using a heating stage in a 200kV electron microscope equipped with a video system for recording dynamic behavior.

In-Situ Observation of Clay Minerals Hydrated and Intercalated With Liquid Chemicals Using Film-Sealed Environmental Cell

1980 ◽  
Vol 38 ◽  
pp. 208-209 ◽  
Author(s):  
K. Fukushima ◽  
N. Kohyama ◽  
A. Fukami
Keyword(s):  
Carbon Film ◽  
Resolving Power ◽  
In Situ Observation ◽  
Interlayer Water ◽  
Saturated Water ◽  
Structure Changes ◽  
Environmental Cell ◽  
Gas Layer ◽  
20 Nm

A film-sealed high resolution environmental cell(E.C) for observing hydrated materials had been developed by us(l). Main specification of the E.C. is as follows: 1) Accelerated voltage; 100 kV. 2) Gas in the E.C.; saturated water vapour with carrier gas of 50 Torr. 3) Thickness of gas layer; 50 μm. 4) Sealing film; evaporated carbon film(20 nm thick) with plastic microgrid. 5) Resolving power; 1 nm. 6) Transmittance of electron beam; 60% at 100 kV. The E.C. had been successfully applied to the study of hydrated halloysite(2) (3). Kaolin minerals have no interlayer water and are basically non-expandable but form intercalation compounds with some specific chemicals such as hydrazine, formamide and etc. Because of these compounds being mostly changed in vacuum, we tried to reveal the structure changes between in wet air and in vacuum of kaolin minerals intercalated with hydrazine and of hydrated state of montmori1lonite using the E.C. developed by us.

Development of Highly Precise Cell Stretching Microdevice and in-situ Observation of Stretched Cell

2013 ◽  
Vol 133 (12) ◽  
pp. 350-357
Author(s):  
Yuta Nakashima ◽  
Ryo Monji ◽  
Katsuya Sato ◽  
Kazuyuki Minami
Keyword(s):  
In Situ Observation ◽  
Cell Stretching
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