Scattering Tomography and Its Application to Sooting Diffusion Flames

1994 ◽  
Vol 116 (1) ◽  
pp. 144-151 ◽  
Author(s):  
M. P. Mengu¨c¸ ◽  
P. Dutta
Keyword(s):  
Diffusion Flames ◽  
Tomographic Reconstruction ◽  
Scattering Coefficient ◽  
Reconstruction Technique ◽  
Transmission Tomography ◽  
Ion Laser ◽  
Series Of Experiments ◽  
Argon Ion ◽  
Good Agreement

A new analytical tomographic reconstruction technique was developed for the determination of the extinction and scattering coefficient distributions in axisymmetric media. This method, called “scattering tomography,” was tested for several particle concentration profiles corresponding to those for diffusion flames. After that, a series of experiments were performed on sooting acetylene flames using an argon-ion laser nephelometer. The experimental results were reduced using both the transmission and scattering tomography techniques to obtain the extinction coefficient profiles. It was shown that in the center of the flame, the results from these two approaches were in good agreement. Scattering tomography can be used to determine both the absorption and scattering coefficient distributions in the medium. In addition to that, it is preferable over the transmission tomography if the medium is optically very thin and particles are predominantly scattering.

Determination of Subnanosecond Fluorescence Lifetimes with a UHF Television Tuner and a cw or Mode-Locked Laser

1986 ◽  
Vol 40 (5) ◽  
pp. 683-687 ◽  
Author(s):  
Frank V. Bright ◽  
Daniel A. Wilson ◽  
Gary M. Hieftje
Keyword(s):  
High Frequency ◽  
Rhodamine 6G ◽  
Instrument Design ◽  
Fluorescence Lifetimes ◽  
New Approach ◽  
Ion Laser ◽  
Subnanosecond Fluorescence ◽  
Argon Ion ◽  
Good Agreement

An inexpensive ultra-high-frequency (UHF) television tuner and an argon-ion laser are employed for the determination of excited-state lifetimes of a series of common fluorophores. Fluorescence lifetimes are determined in the frequency domain; the results are in good agreement with previously reported values and demonstrate the utility of the new approach for subnanosecond measurements. Binary mixtures of rhodamine 6G and rose bengal can also be resolved with the use of this novel instrument design.

Determination of Organics on Metal Surfaces by Raman Spectroscopy

1993 ◽  
Vol 47 (11) ◽  
pp. 1767-1771 ◽  
Author(s):  
Ching-Hui Tseng ◽  
Charles K. Mann ◽  
Thomas J. Vickers
Keyword(s):  
Fiber Optic ◽  
Laser Excitation ◽  
Internal Standard ◽  
Aluminum Surface ◽  
Hadamard Transform ◽  
Dimethyl Methylphosphonate ◽  
Argon Ion Laser ◽  
Ion Laser ◽  
Argon Ion

Detection limits of about 1 g/m2 are demonstrated for the Raman determination of two organic materials, polydimethylsiloxane and dimethyl methylphosphonate, on an aluminum surface. A fiber-optic-based system is used. A large sample area is scanned to overcome heterogeneity in sample coverage. Measurements are made without use of an internal standard. Results are reported for both a Hadamard transform technique with argon-ion laser excitation and a conventional spectrometer with diode laser excitation.

Characterization of Matrix-Assisted Laser Desorption Based on Absorption and Acoustic Monitoring

1995 ◽  
Vol 49 (12) ◽  
pp. 1826-1833 ◽  
Author(s):  
Jan Preisler ◽  
Edward S. Yeung
Keyword(s):  
Atmospheric Pressure ◽  
Accurate Determination ◽  
Optimal Conditions ◽  
Plume Velocity ◽  
Ion Laser ◽  
Optical Probing ◽  
Argon Ion ◽  
Reduced Pressures

Conventional methods for studying matrix-assisted desorption-ionization rely on mass spectroscopy. In this study, a 488-nm argon-ion laser beam is deflected by two acoustooptic deflectors to image plumes desorbed at atmospheric pressure via absorption. All species, including neutral molecules, are monitored. Interesting features, e.g., differences between the initial plume and subsequent plumes desorbed from the same spot, or the formation of two plumes from one laser shot, are observed. Total plume absorbance can be correlated with the acoustic signal generated by the desorption event. A model equation for the plume velocity as a function of time is proposed. Optical probing also enables accurate determination of plume velocities at reduced pressures. These results define the optimal conditions for desorbing analytes from matrices, as opposed to achieving a compromise between efficient desorption and efficient ionization as is practiced in mass spectrometry.

scholarly journals Dynamic Tomographic Reconstruction of Deforming Volumes

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1395 ◽  
Author(s):  
Clément Jailin ◽  
Stéphane Roux
Keyword(s):  
Tomographic Reconstruction ◽  
Large Strains ◽  
Reconstruction Technique ◽  
Proof Of Concept ◽  
Volume Reconstruction ◽  
Multi Scale ◽  
Proper Volume ◽  
Step Algorithm ◽  
And Performance

The motion of a sample while being scanned in a tomograph prevents its proper volume reconstruction. In the present study, a procedure is proposed that aims at estimating both the kinematics of the sample and its standard 3D imaging from a standard acquisition protocol (no more projection than for a rigid specimen). The proposed procedure is a staggered two-step algorithm where the volume is first reconstructed using a “Dynamic Reconstruction” technique, a variant of Algebraic Reconstruction Technique (ART) compensating for a “frozen” determination of the motion, followed by a Projection-based Digital Volume Correlation (P-DVC) algorithm that estimates the space/time displacement field, with a “frozen” microstructure and shape of the sample. Additionally, this procedure is combined with a multi-scale approach that is essential for a proper separation between motion and microstructure. A proof-of-concept of the validity and performance of this approach is proposed based on two virtual examples. The studied cases involve a small number of projections, large strains, up to 25%, and noise.

A New Technique for the Elimination of Fluorescence Interference in Raman Spectroscopy

1986 ◽  
Vol 40 (5) ◽  
pp. 583-587 ◽  
Author(s):  
Frank V. Bright ◽  
Gary M. Hieftje
Keyword(s):  
Raman Spectroscopy ◽  
Rhodamine 6G ◽  
Microwave Spectrum ◽  
New Instrument ◽  
Ion Laser ◽  
A New Technique ◽  
Relative Errors ◽  
Argon Ion ◽  
Raman Scatter ◽  
Good Agreement

A new instrument for Raman spectroscopy has been constructed with the use of a cw or mode-locked argon-ion laser as the excitation source and a microwave spectrum analyzer for discrimination between fluorescence and Raman scatter. To demonstrate the new instrument's capability, the weak Raman scatter of water was resolved from the intense fluorescence from rhodamine 6G. Theoretically predicted relative errors in the new procedure are calculated and experimental results are shown to be in good agreement with theory.

The Development of a Doppler Global Velocimeter for Transonic Turbine Applications

1994 ◽  
Author(s):  
Roger W. Ainsworth ◽  
Steven J. Thorpe
Keyword(s):  
Continuous Wave ◽  
Ccd Camera ◽  
Single Mode ◽  
Rotating Disc ◽  
Iodine Cell ◽  
Ion Laser ◽  
Transonic Turbine ◽  
Argon Ion ◽  
Frame Grabber

The development of a Doppler Global Velocimeter (DGV) for the measurement of transonic turbo-machinery flows in the Oxford Isentropic Light Piston Tunnel rotor facility is described. A novel optical arrangement for capturing both reference and iodine cell discriminated images with a single CCD camera and frame grabber is presented. Practical arrangements for determination of the iodine cell transmission properties as a function of temperature and light frequency are discussed in the context of using an argon ion continuous wave laser for illumination. Flow seeding aspects of the experiment are described with particular emphasis on particle dynamics and light scattering. Error bounds for the DGV measurements are assessed and quantified in respect to the frame grabber resolution and Gaussian beam profile. Results of measurements of the velocity of a rotating disc with tip speed of nominally 90 m/s, obtained with 0.5 W single mode argon ion laser illumination are presented. Practical aspects for employing the DGV on the established Oxford rotor facility, such as seeding of the flow, optical access and synchronisation of data acquisition are addressed.

scholarly journals Comparison of Hydraulic Conductivity Values Obtained from Empirical Formulae and Laboratory Experiments

2020 ◽  
Vol 68 (4) ◽  
pp. 669-678
Author(s):  
Mario Hala ◽  
Lubomír Petrula ◽  
Zakaraya Alhasan
Keyword(s):  
Experimental Data ◽  
Hydraulic Conductivity ◽  
Laboratory Experiments ◽  
Internal Erosion ◽  
Variable Porosity ◽  
Groundwater Flow Regime ◽  
Series Of Experiments ◽  
Different Grain Size ◽  
Good Agreement

Hydraulic conductivity determination plays an essential role in the investigation of groundwater flow regime which can then influence many field problems such as pumping capabilities in the area, transport of contaminant or heat and soil internal erosion. Numerous equations based on dimensional analysis or experimental measurements have been published since the end of the 19th century for the determination of hydraulic conductivity. However, not all of these formulae are applicable for every material and all of them bring some uncertainty in the value of hydraulic conductivity. This paper contains a description of experimental research carried out concerning the determination of hydraulic conductivity for four types of sand with different grain size distribution curves and variable porosity. Obtained values of hydraulic conductivity ranged from 1 × 10-4 to 4 × 10-3 according to the sample porosity. The series of experiments consisted of 160 separate tests conducted in order to obtain relevant statistical sets. In this paper, the experimental data are discussed and compared with hydraulic conductivities obtained from 6 empirical formulae recommended in a previous study. The comparison showed that some empirical formulae provide a good agreement with the experimental data (the most precise were formulae published by Terzaghi and by Sauerbrey). However, some formulae showed high deviation from measured data (formula published by Zamarin).

Determination of Azo Dyes by Resonance-Enhanced Raman Spectroscopy

1987 ◽  
Vol 41 (1) ◽  
pp. 117-119 ◽  
Author(s):  
James D. Womack ◽  
Thomas J. Vickers ◽  
Charles K. Mann
Keyword(s):  
Raman Spectroscopy ◽  
Azo Dyes ◽  
Internal Standard ◽  
Nonlinear Behavior ◽  
Limits Of Detection ◽  
Eriochrome Black T ◽  
Exciting Beam ◽  
Ion Laser ◽  
Argon Ion

An examination of the feasibility of using Raman spectroscopy to determine strongly absorbing solutes has been made, with the use of the azo dyes Eriochrome Blue SE, Eriochrome Black T, and Eriochrome Blue Black B as target compounds. These compounds are representative of the large class of dyes which are not easily determined because of their low volatility. They also are examples of compounds which absorb strongly, causing pronounced nonlinear behavior when attempts are made to use resonance-enhanced bands to improve analytical limits of detection, and which produce intense fluorescence which interferes with Raman bands when the strong 514-nm band of the argon-ion laser is used for excitation. The efficacy of internal standard correction for eliminating the effects of self-reversal and variation in intensity of the exciting beam is demonstrated. Limits of detection for the three compounds listed above are 99 ppb, 340 ppb, and 1.5 ppm, respectively.

Sign in / Sign up

Export Citation Format

Share Document