IMAGING
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`TECHNOLOGIES
`
`Techniques and Applications
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`5
`
`THE SECOND INTERNATIONAL CONFERENCE
`
`Sponsored by
`The Engineering Foundation
`and
`
`The Amen'can Society of Civil Engineers
`Technical Council on Computer Practices
`Imaging Technologies Committee
`
`Approvedforpublication by the Technical Council on Computer Practices
`ofthe American Society of Civil Engineers
`
`in Civil Engineering PROCEEDINGS OF
`
`SmMii‘zgztEfifi‘PdE RTY 0F
`1%meDOT LIBRAR‘ 1
`SueMcMinnesota Department
`of Transportation
`
`Ase American Society
`of Civil Engineers
`
`
`
`Tennant Company
`Exhibit 1033
`
`

`

`FOREWORD
`
`gmeedng Foundation and the Nationai Science Foundation cosponsored a
`
`Library ofCongress Cataloging~in-Publication Data
`1131106 fintitied "Digital Image Processing: Techniques and Applications in Civil
`
`g" that was held in Hawaii in March, 1993. The purpose of the conference
`
`rovide an opportunity for researchers and practitioners from academia,
`
`
`rnment and industry to convene and exchange information and ideas. Despite the
`
`that there were a significant number of peopie beginning to use image processing
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`hniques in a range of civil engineering applications at that time, there had never been
`
`" " ting of the type held. The conference thus provided an efficient means for transfer
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`ortnation between those already actively using the technology, as well as to
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`orm those considering use of digital image processing of the potential benefits. The
`roceedings of the conference were published by ASCE in 1993.
`
`
`
`
`'o facilitate continued exchange of information and ideas, the Second International
`ouferenoe on Imaging Technologies: Techniques and Applications in Civil
`ngineering was held in Davos, Switzerland in May, 1997. As with the first meeting,
`
`eintent was to create an opportunity for practitioners and academicians from a variety
`
`
`: of agencies to learn of continued developments and applications in the field. As with all
`
`
`0t limited m f . yam utilizing this
`.
`'_
`"Engineering Foundation conferences, the meeting agenda included significant
`11
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`u
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`“figment °f 9113’ Patent 0r _*
`opportunities for ad-hoc d1scuss1on among the partic1pants as well as more structured
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`sessions with presentations of technical papers submitted by participants in topics
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`ranging from material characterization, defamation measurements, pavement distress,
`infrastructure maintenance, object recognition, particle sizing and image generation.
`
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`- Céprfrighr e 199819"
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`9,;
`All Rights Reich; £51m Amen“ 5°61th ofcan;
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`. The opening keynote lecture was given by Professor Murat Kunt from the Swiss
`ran 0-7344.og3r;§f2qaial°g Card N01? 971346793
`_
`. Federal Institute of Technology in Lausanne. His presentation entitled “Image Coding:
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`Manufactured in the United States ofAmerica
`' From Pixels to Objects” provided an excellent summary of classical compression
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`I
`techniques as well as a glimpse of where the field is headed, particularly with respect to
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`dynamic coding techniques.
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`
`
`Contents
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`......
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`............................................................................. ix
`
`erence Participants
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`Submitted Papers
`Using Imaging Technologies in Experimental Geotechnics ................................1
`'Heetierickus G.B. Aliersma
`Measurement of Displacement Field by ‘Matching Method” and Observation
`
`Strain Localization in Soft Rock .....................................................................................10
`
`' HY Horii, K. Takamatsu, J. Inoue, and N. Sasaki
`umerical Image Processing in Cetrifuge Testing ..............................................................20
`
`Jean Charrier, Jean-Marc Moiiard= and Jacques Garnier
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`Ali-Attempt to Compare Image Processing and Stereophotogrammetry
`
`in Geotechnical Centrifuge Models ........................................
`.....
`Pierre Chambon, Louis-Marie Cottineau, and Jacques Desrues
`
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`Geo-Material Characterization Using Digital Micrograph Analysis.................................66
`'
`Dayakar Penumadu and Ian Hazen
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`Fourier Morphological Descriptors of Aggregate Profiles..................................................76
`
`._
`'
`Lin-Bing Wang, James S. Lai, and J. David Frost
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`I Methods for Soil Characterization from Images of Grain Assemblies..............................88
`Roman D. Hryciw, Ali M. Ghalib, and Scott A. Raschke
`
`. Application of Digital Image Analysis for Size Distribution Measurements
`- of Microbubbies......
`............................................... 100
`Susan E. Bums, Sotira Yiacoomi, J. David Frost, and Costas Tsouris
`
`'I'D termination ofVoid Fabric Tensor of Soils Without Radial Sampling Bias40
`Baiasingam Muhunthan and Eyed Masad
`
`cent Studies in Geotechnical Image Analysis ..................................................................56
`-' D. Luo, X. Long, X. Xue, A.E. Henderson, J. Cowan, J.E.S. Macleod= and
`P‘ Smart
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`'
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`_'
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`.....
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`..........30
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`A Model for Imaging Assisted Automation of Infrastructure Maintenance..............108
`Carl Haas, Young-Suk Kim, and Richard Greer
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`Fuzzy Logic Distress Classifier for Pavement Imaging.....................................................118
`Gary R. Smith and Chien-Liang Lin
`Pavement Condition Assessment Using Ground Penetrating Radar-128
`Michael Heiier and Sue McNeil
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`Segmentation Algorithm Using Iterative Clipping for Processing Noisy Pavement
`Images
`......................................................... 138
`
`

`

`Application of Digital lmage Analysis for Size Distribution
`Measurements of Microbubbles
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`10}
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` SIZE DlS'l'RIBUTION WASUREMENTS 0F MICROBUBBLES
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`
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`' solution; consequently, the low density solids are floated to the top of the column for
`removal by skimming. The process of flotation is known as dissolved air flotation if
`the microbubbles are produced by pressurizing air into water, as dispersed air
`
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`flotation if the bubbles are produced by forcing gas through a sparger, and as
`electrotlotation if the bubbles are produced through the electrolysis of water. This
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`_ study will focus on bubbles generated by electroflotation.
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`
`
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`Electroflotation has been used by the mineral processing industry for the
`recovery of mineral particles (Ketkar et a1., 1991), and in environmental and
`industrial processes for the separation of oil from oil/water emulsions (Hosny, 1992;
`Balmer and Foulds, 1986), and for the removal of coagulated heavy metals from
`-- solution (Srinivasan and Subbaiyan, 1989; Ramadorai and Hanten, 1986).
`In all of
`i
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`these applications, the removal efficiency is strongly affected by the size of the
`
`generated bubbles. Smaller bubbles have a longer residence time in the system, have
`a larger surface area, and are more likely to adhere to solids after a collision (de Rijk
`'3 et a1., 1994). Consequently, the treatment process is optimized by generating the
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`smallest diameter bubbles possible.
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`
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`Susan E. Burns‘, Sotira Yiacoumi', J. David Frost‘, and Costas Tsouris2
`
`This work employs digital image analysis to measure the size distribution of
`microbubbles generated by the process of electroflotation for use in solid/liquid
`separation processes. Microbubbles are used for separations in the mineral
`processing industry and also in the treatment of potable water and wastewater. As
`the bubbles move upward in a solid/liquid column due to buoyancy, particles collide
`with and attach to the bubbles and are carried to the surface of the column where they
`are removed by skimming. The removal efficiency of solids is strongly affected by
`the size of the bubbles. In general, higher separation is achieved by a smaller bubble
`The primary focus of this study was to characterize the size and size
`distribution of bubbles generated in electroflotation using image analysis. The study
`found that bubble diameter increased slightly as the current density applied to the
`system was increased. Additionally, electroflotation produces a uniform bubble size
`with narrow distribution which optimizes the removal of fine particles from solution.
`
`Many environmental and industrial treatment processes rely on the separation
`of solid particles from liquid solutions. Traditionally, solid particles are removed by
`sedimentation; however, sedimentation does not work well for low density particles
`like clay minerals, spores, and coagulated fulvic acids (Edzwald et a1., 1992; Malley
`and Edzwald, 1991; Letterman, 1987). As a result, a method known as flotation,
`which floats rather than sediments low density particles,
`is being used more
`in flotation, small gas bubbles are generated at the bottom of the water
`column to be treated. The microbubbies then rise to the surface of the liquid through
`buoyancy. As the bubbles rise, they collide with and adsorb to particles in the
`
`1 Graduate Research Assistant and Associate Professors, respectively, Georgia institute of
`
`
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`
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`This paper examines the effect of the process variables of voltage, current,
`_ and ionic strength on the size of the bubbles generated during electroflotation.
`Bubble images were recorded with a long—distance, high—magnification microscope,
`
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`and were printed and imported into a digital image analysis system for measurement
`of equivalent bubble diameter. The average equivalent circular diameter for was
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`calculated for each experimental condition; additionally, the volume distribution of
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`the bubbles was calculated for each experiment.
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`Experimental
`
`The rectangular test cell used in the experiments of this study was made of
`Plexiglas with dimensions of 58.4 cm by 7.6 cm by 2.5 cm.
`inflow and outflow
`ports were drilled in the top and bottom of the cell and it was mounted vertically in
`order to allow gas flow out the top. After the cell was filled with the test solution, a
`soap-film flow meter was attached to one outflow port to measure gas flow rate and
`the remaining outflow ports were sealed. The electrodes used in the experiments
`were polished graphite electrodes (7.6 cm by 2.5 cm by 1.3 cm) and were mounted at
`the bottom of the cell with a separation of 13 cm. Electrical leads were attached to
`the electrodes using conductive epoxy, and then connected to an external power
`supply.
`
`Twenty eight experiments were performed using aqueous solutions of
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`SIZE DISTRIBUTION MEASUREMENTS OF MICROBUBBLES
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`11 : [Zara(7)2
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`IMAGING TECHNOLOGIES
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`distance microscope with a magnification of approximately 230 times attached to a
`video camera, monitor, and VCR. The calibration factor was a wire of known
`diameter. The experiments performed at 0.001 M did not produce a significant gas
`flow rate; consequently, only the results for the experiments performed at 0.1 and
`0.01 M are reported in this paper.
`
`The gas bubbles produced in electroflotation form through the electrolysis of
`water by the following redox reactions:
`
`H20 m) 2H+ 4%02 (g) + Ze'
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`Anode(+)
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`2H,o + 2c" —> QOH’ + H, (g)
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`Cathode(—)
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`The oxygen and hydrogen gas dissolve into the liquid surrounding the electrodes;
`when the liquid becomes supersaturated with gas, bubbles begin to form on the
`electrode surface (Verhaart et al., 1980). The camera was focused on the bottom
`electrode in the test cell and two experiments were performed at each power level. In
`the first experiment,
`the bottom electrode was the anode, and in the second
`experiment the electrical
`leads were reversed making the bottom electrode the
`cathode. This configuration was used because it prevented the mixing of oxygen and
`hydrogen bubbles during videotaping. A light source was set up behind the ceil to
`produce contrast between the bubbles and the solution in the recorded images.
`
`Image Processing and Analysis
`
`After the experiments were completed, the images were printed to hard copy
`using a video copy processor and imported into a Quantirnet Q570 Digital Image
`Processor. The printed images were gray—scale pictures of dark bubbles on a light
`background because the light source behind the cell was blocked by the bubbles but
`passed through the aqueous solution. After the images were acquired by the image
`processor, they were converted from gray-scale into digital images and a minimal
`amount of image processing was performed.
`In some instances, background noise
`occurred on the images and was erased. Additionally, sometimes two bubbles
`touched each other on the images. In this case, the bubbles were either separated and
`analyzed individually, or were eliminated from the image. No other
`image
`processing was performed on the bubble pictures. Because not all of the bubbles
`were circular in cross~section, the image analyzer measured the area of each bubble
`and converted that to an equivalent circular diameter for the output.
`
`A statically valid sample size was chosen for anaiysis by first determining the
`error in the measurement. Measurements of one experiment were performed twice
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`
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`'Figure 1. Oxygen bubble diameter as a function of current density: I = 0.1 M
`
`Where n = sam le size, Z
`error.
`13
`ag/g
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`2
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`‘
`_
`»
`-
`confidence interval, 0' m standard deviation, and E 2
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`Results
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`'
`Figure 1 shows a plot of the equivalent circula
`.
`.
`r diameter of oxygen bubbles
`as a function of current densrty. The figure shows a trend of slightly increasing
`-. bubble diameter with increasing current density applied to the system. This is
`consistent with other electroflotation results using metallic electrodes (Brandon and
`Kelsall, l985; Janssen and Hoogland, 1973; Landoit et al., 1970). The formation f
`bubbles in electroflotation is an inhomogeneous, or surface controlled process rath:
`than a homogeneous process where the bubbles form out of solutibn without thr
`presence of a surface. Previous research has found that bubbles will form at the
`location of scratches and pits on the electrode surface (Janssen and Hoogland 197;
`Glas and Westwater, 1964) which illustrates the importance of the surf
`9
`characteristics of the electrodes.
`In this study, the electrodes were not polislilgd
`between successive experiments which most likely explains the scatter seen in the
`average bubble diameter measurements, because the application of current wilt affect
`the surface characteristics of the electrode. Average oxygen and hydrogen bubble
`diameters measured in the experiments ranged from 17.1 to 37.9 pm which is
`consistent with the size of bubbles produced on stainless steel and platinum
`' electrodes (Ketkar et al., 1991).
`
`35
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`AverageBubbleDiameter (F
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`0
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`20
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`40
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`60
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`30
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`100
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`IMAGING TECHNOLOGIES
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`No clear trends in bubble size were seen as a function of voltage or as a
`function of ionic strength; however,
`the volume of gas generated was a strong
`function of both power input to the system and of ionic strength of the surrounding
`medium. As would be expected,
`the generation of hydrogen and oxygen gas
`increased as both the power input to the system was increased and as the more
`strength of the aqueous medium was increased.
`
`The voiuine distribution of the generated bubbles was also plotted for
`comparison between the experimental conditions. Figures 2 and 3show the volume
`
`1.0
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`0.8
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`0.6
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`0.4
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`0.2
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`
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`CumulativeVolume
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`Figure 2(b). Cumulative volume distribution for oxygen bubbles: I = 0.1 M.
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`Distribution 0.0
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`.
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`0
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`5°
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`100
`
`150
`
`Bubbte Diameter (u m)
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`Figure 2(a). Cumulative volume distribution for hydrogen bubbles: I = 0.1 M.
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`1.0
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`
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`CumulativeVolume
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`Distribution
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`0
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`50
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`100
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`150
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`Bubble Diameter (urn)
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`SIZE DISTRIBUTION REASUREMENTS OF lVflCROBUBBLES
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`105
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`distribution of both the oxygen and hydrogen bubbles produced at ionic strengths of
`0.1 and 0.01 M and at power levels ranging from 0.255 to 2.070 W. The distribution
`plots show that electroflotation produces bubbles with fairly uniform diameters The
`moet common range in bubble diameters is approximately 60 pm, which is a rather
`narrow distribution for flotation methods. Additionally, the majority of the bubbles
`produced have diameters smaller than 50 pm which increases the removal efficienc
`of fine particles from the solution. However, as was seen with average bubblZ
`diameter, no distinct trends in the distribution are seen as functions of either power or
`ionic strength.
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`
`
`CumulativeVolume
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`Distribution
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`0
`
`100
`50
`Bubble Diameter (M m)
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`150
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`1.0
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`
`
`CumulativeVolume
`
`0.8
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`0.6
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`0.4
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`Distribution
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`O
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`50
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`100
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`150
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`]M AGING TECHNOLOGIES
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`SIZE DISTRIBUTION MEASURENLENTS OF MICROBUBBLES
`
`107'
`
`image analysis provided an efficient method for measuring the
`average equivalent diameter of microbubhles produced by electroflotation. The use
`of automated measuring processes allowed for the rapid determination of bubble size
`and eliminated the measurement errors which can occur in manual measurements.
`Because the measurement process is faster using an image analyzer than manual
`measurements, a larger sample space can be used and/or more experiments can be
`performed allowing for more complete data sets.
`
`In these experiments, the average bubble diameter increased as the current
`density applied to the system was increased, No trends were identified in bubble
`diameter as a function of either power or ionic strength of the aqueous medium;
`however, gas flow rate increased as both power and ionic strength were increased.
`The volume distribution of the generated bubbles showed that electroflotation
`produces bubbles with fairly uniform diameters and narrow ranges. Again, no trends
`were identified in distribution as functions of either power or ionic strength.
`
`Acknowled ments
`
`The authors thank Ken Thomas for his assistance with equipment preparation.
`Partial financial support from the Division of Chemical Sciences, Office of Energy
`Sciences, US Department of Energy, under contract DE-AC05-96OR22464 with
`Lockheed Martin Energy Research Corp, is gratefully acknowledged.
`
`
`from Oil/Water Emulsions Using and
`(1992). Separation of Oil
`Hosny, A.Y.
`'
`'
`Electroflotation C 11
`'
`V01. 5’ 131141942:-
`‘Wlth Insoluble Electrodes, Filtration and Separation,
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`Janssen, L. J. J. and Hoogland, J. G. (1973). The Effect of Electrolytically Evolved
`Gas Bubbles on the Thickness of the Diffu '
`‘
`‘
`Acm’ V01, 13, pp. 543—550.
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`
`
`_
`" Ketkar, D.R., Mailikarjunan, R., and Venkatachalam, S. (1991), Electroflotation of
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`'
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`Landolt, D., Acosta, R., Muller, R.H., and Tobias, CW. (1970). An Optical Study of
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`
`,
`.
`.
`tratron, Journal
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`'
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`'
`Works Association, Vol. 12, pp. 26-32.
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`‘- Malley,CJ.P. apd Eldrlawald, J.K.
`(1991). Laboratory Comparison of DAF with
`onven iona
`reatrnent, Journal 0 the Ame '
`'
`'
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`VOL 9’ p11 55- 61‘
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`_
`o
`uen s
`t t'
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`'
`'
`pp. 149-154.
`y
`o a ton, Minerals and Metallurgical Processzng, August,
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`Srrmvasgiéi, V: and Subbaiyan, M. (1989). Electroflotation Studies on Cu, Ni Zn and
`With Anunomum Dodecyl Dithiocarbarnate, Separation Science= ana1
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`_
`Technology, Vol. 24, No. 1&2, pp. 145-150.
`- Verhaart, H.F.A., DE longe, R.M., and VAN Stralen, S.J.D. (1980). Growth Rate of a
`Gas Bubble During Electrol
`'
`'
`'
`‘
`ysrs in Supersaturated L1 urd I t
`'
`Journal ofHeat andMass Transfer, Vol. 23, pp. 293-299.q
`,
`n emalmnal
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`'
`
`I
`
`from Oil-in—Water
`(1986). Separating Oil
`Balmer, L. M. and Foulds, A. W.
`Emulsions by ElectroflocculationfElectroflotation, Filtration and Separation,
`Vol. 6, pp. 366-370.
`.
`(1985). Growth Kinetics of Bubbles
`Brandon, NP.
`and Kelsall, G.H.
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`DE Riik, S.E, VAN DER Graaf, J.H.J.M., and DEN Blanken (1994). Bubble Size in
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`Flotation Thickening, Water Research, Vol. 28, No. 2, pp. 465—473.
`Edzwald, J.K., Walsh, J.P., Kaminski, G.S., and Dunn, HJ. (1992). Flocculation and '
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`Works Association, Vol. 3, pp. 92-100.
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`‘
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