Digital Image Analysis Techniques Research Articles

Relationship between Surface Froth Features and Flotation Indexes in the Flotation of a Sulphide Copper Ore

Froth images are pre-processed, which are acquired at the flotation laboratory. Digital image analysis techniques are used to analysize these froth images and their grey histogram and to extract statistical texture features of those froth images. Finally, the relation model for statistical texture features of those froth images and flotation index is established by RBF neural networks. A simulation showed that the relation model is higher precise

나노유체 액적의 젖음거동 및 증발 특성

This study investigates experimentally evaporation characteristics of nanofluid droplets containing 50 nm alumina() particles and the wettability changes on a hydrophilic glass surfaces. From the captured digital images by using a CMOS camera and a magnifying lens, we examined the effect of particle concentration on droplet evaporation rate which can be indirectly deduced from the measured droplet volumes varying with time. In particular, with the use of a digital image analysis technique, the present study measured droplet perimeters and the contact angles to study the wetting dynamics during evaporating process. In addition, we compared the measured total evaporation time with theoretically estimated values. It was found that as the volume fractions of nanofluid increased, the total evaporation time and the initial contact angles decreased, while the droplet perimeters increased.

Improved Image Analysis of DETECHIP® Allows for Increased Specificity in Drug Discrimination

DETECHIP® is a novel molecular sensing array being developed for the detection and identification of a variety of compounds including controlled substances. This easy to use technology has the ability to produce a unique identifying binary code for each substance tested. Original analysis methodology relied on human vision to classify color and fluorescence changes within the array. New digital color image analysis techniques using red-green-blue (RGB) color values provided a higher degree of specificity and greater consistency. This image analysis technique was able to detect more subtle changes in color and was therefore able to properly discriminate between substances that previously produced identical codes. This technique was also expanded to analyze changes in RGB color values individually, increasing the length of the code to 48 digits and therefore potentially providing a further increase in specificity. To show the applicability of this new method, a blind study was performed, correctly identifying two unknown analytes.

In situ demonstration and quantitative analysis of the intrinsic properties of glycoside hydrolases

Based on digital image analysis techniques and a series of optimizations in native electrophoresis, a new direct method to simultaneously detect the intrinsic properties of each active component in the enzymatic system of glycoside hydrolase was established. The key technique is that the concentration changes of substrate (or product) on the gel can be determined quantitatively by the gray value changes of the corresponding band after electrophoretic separation. In this manner, the catalytic characteristics of each glycoside hydrolase component were demonstrated in situ and were easily determined after immersing the gel in a series of solutions containing substrates or their derivatives. Because of its high throughput, great sensitivity, and convenient operation, this method can be used to demonstrate the natural diversity of glycoside hydrolases and to study spatial and temporal regulation in multienzyme expression systems. Thus, it is an effective approach to study the functional proteomics of glycoside hydrolases.

Characteristic analysis on temporal evolution of floc size and structure in low-shear flow

A series of flocculation tests were performed to investigate the effect of low-shear rates ( G = 3–16 s −1) on flocculation of kaolin suspension by polyaluminum chloride (PACl), with the goal of understanding floc growth mechanisms. Results were reported in terms of floc average size ( d p ) and boundary fractal dimension ( D pf ), derived from a non-intrusive optical sampling and digital image analysis technique. As expected, the rate of floc aggregation increased with increasing G, resulting in faster changes in aggregate size and structure in the initial stage of flocculation. Nevertheless, steady state was attained faster for D pf than for d p at the same shear rates, possibly due to the self-similarity of fractal aggregates. An interesting finding was that at G = 3 s −1, an obvious plateau was observed for the average-size evolution at steady state; for shear rates of 6 and 7 s −1, the flocs exhibited some decrease after reaching the peak of size, mainly as a result of floc settling at steady state; and for G = 11–16 s −1, a decrease in floc size was possibly attributed to the irreversibility of PACl-floc breakage. The process of floc growth was described using a fractal growth model, which defined flocculation as the result of the combined processes of aggregation and restructuring. The conceptual model could effectively characterize temporal changes in floc size and structure, and found that fragmentation followed by reformation seemed to be more effective in forming larger and more compact aggregates than the restructuring process due to erosion and reformation, which may provide useful insights for the design of flocculation reactors.

Effect of Strain Rate on the Stress-Strain Behavior of Sand

Drained triaxial compression tests on crushed coral sand were performed from near-static strain rates to very high strain rates (up to approximately 1,800%/s). Experiments were performed on dry, vacuum-confined axisymmetric specimens at two different confining pressures (98 and 350 kPa) and two different densities (Dr approximately 36 and 60%). A gravity drop weight loading system was used to generate high strain rates. High-speed film photographs of the specimen were taken through the flat sides of a square triaxial cell. By using digital image analysis techniques, strains were locally measured near the center of the specimen to obtain the most uniform assessment. Stress-strain relationships are presented. The following effects were observed with increasing strain rates: the elastoplastic stiffness increased significantly; the failure shear strength increased moderately; the axial strain at peak stress decreased significantly; and volumetric strains became more dilatant. Unusual behavior was observed at ...

Centrifuge model study on low permeable slope reinforced by hybrid geosynthetics

The objective of this paper is to study the performance of hybrid geosynthetic reinforced slopes, with permeable geosynthetic as one of its components, for low permeable backfill slopes subjected to seepage. Four centrifuge tests have been performed to study the behavior of hybrid geosynthetic reinforced slopes subjected to seepage, keeping the model slope height and vertical spacing of geosynthetic reinforcement layers constant. Centrifuge model tests were performed on 2V:1H slopes at 30 gravities. One unreinforced, one model geogrid reinforced and two hybrid geosynthetic reinforced slope models with varying number of hybrid geosynthetic layers were tested. The effect of raising ground water table was simulated by using a seepage flow simulator during the flight. Surface movements and pore water pressure profiles for the slope models were monitored using displacement transducers and pore pressure transducers during centrifuge tests. Markers glued on to geosynthetic layers were digitized to arrive at displacement vectors at the onset of raising ground water table. Further, strain distribution along the geosynthetic reinforcement layers and reinforcement peak strain distribution have been determined using digital image analysis technique. The discharge for the performed model tests is determined by performing seepage analysis. It was confirmed by the centrifuge tests that the hybrid geosynthetics increases the stability of low permeable slope subjected to water table rise. The hybrid geosynthetic layers in the bottom half of the slope height play a major role in the dissipation of pore water pressure.

Numerical simulation and experimental validation of bubble behavior in 2D gas–solid fluidized beds with immersed horizontal tubes

The two-fluid model based on the kinetic theory of granular flow is considered to be a fundamental tool for modeling gas–solid fluidized beds and has been extensively used for the last couple of decades. However its verification and quantitative validation still remain insufficient for a wide range of reactor geometries and operating conditions. In this study simulations were performed using the two-fluid model for two-dimensional (2D) bubbling gas–solid fluidized beds with and without immersed horizontal tubes. The bubble characteristics – aspect ratio, shape factor, diameter and rise velocity – predicted by the simulation were compared and validated with experimental data obtained from pseudo-2D fluidized beds using digital image analysis technique. The predicted bubble shape and diameter were in good agreement with the experimental data for fluidized beds with and without immersed tubes. The simulation predicted higher bubble rise velocity compared to the experimental results obtained. This was due to the wall effect, which was not taken into consideration during the 2D simulation. In addition the influences of different drag laws, friction packing limits and solid-wall boundary conditions on the different bubble properties were investigated. The results showed that the choice of friction packing limits, drag laws and specularity coefficients have little influence on bubble properties.

EVALUATION OF MULTI-SENSOR REMOTE SENSING DATA APPLIED OIL AND GAS EXPLORATION IN THE LOESS HIGHLANDS, ORDOS PLATEAU, CHINA

Satellite remote sensing technology is developing rapidly worldwide. New sources of the remote sensing data and digital image analysis techniques can be applied to the field of oil and gas exploration. This study examines and evaluates multi-sensor remote sensing data in the context of a comprehensive geology investigation in the Loess Highlands of the Ordos Plateau in China. Implications for further investigations are discussed.

흙의 변형 측정을 위한 디지털 이미지 해석 기법의 최적화 및 정확도 평가

Digital image analysis techniques have been developed and utilized in the field of solid mechanics and fluid mechanics to measure the deformation and velocity of a target object. The deformation measurement systems based on Particle Image Velocimetry (PIV) and Digital Image Correlation (DIC) have been attempted in geotechnical testings (e.g., physical model tests) for observing the deformation of soils. The digital image analysis is influenced by image pattern of test materials, resolution of the used digital camera, target area, image analysis techniques, and analysis conditions. Therefore, optimal analysis conditions should be determined to obtain high quality results on soil deformations. In the present study, various influence factors on the digital image analysis were described and summarized. The optimizing procedure for high accurate results was then proposed. Finally, the applicability of the developed procedure was examined.

Numerical and Experimental Investigation of Bubbling Gas–Solid Fluidized Beds with Dense Immersed Tube Bundles

Numerical simulations of gas–solid bubbling fluidized beds with and without dense immersed horizontal tubes were performed using the Eulerian-Eulerian Two Fluid Model (TFM) and applying the Kinetic Theory of Granular Flow (KTGF). The results were compared with experimental data obtained from a pseudo-2D fluidized bed test rig using a developed digital image analysis technique (DIAT). The influences of dense immersed horizontal tubes on bed properties (bed pressure drop and expansion ratio) and bubble hydrodynamics (bubble size, rise velocity, aspect ratio, and shape factor) were investigated numerically as well as experimentally. In the first part grid sensitivity with different mesh sizes was checked and effects using 2D and 3D domains were examined. Simulations with 3D domains gave better agreement with experimental data but were seen to be computationally expensive. For conducting intensive parametric studies of fluidized bed behavior the use of 2D domains remains indispensable. In the second part it could be shown that dense tube arrangements in the fluidized bed lead to repeated bubble break-up and coalescence in the tube bank region and therefore to fluctuating values of bubble size, rise velocity, aspect ratio, and shape factor. For different superficial velocities similar results were found which shows the high influence of dense immersed tubes on fluidized bed behavior. In addition no significant differences between staggered and in-line tube arrangement were observed. In general the simulations based on the Two Fluid Model showed good agreement with the experimental results.

평면변형률 시험에서 이미지 해석을 통한 사질토의 전단면 특성 평가

전단면의 형성과 전단면에 집중되어 국부적으로 발생하는 변형은 지반 구조물의 거동과 안정성에 크게 영향을 미치기 때문에 전단면의 특성을 파악하는 것은 매우 중요하다. 본 연구에서는 전단면의 형성 및 발달 패턴 등을 실험적으로 규명하기 위하여 입도분포가 다른 세 가지 시료에 대하여 밀도와 구속압 조건을 변화시켜가면서 평면변형률 시험을 수행하였다. 전단 중에 이미지를 촬영하고, 전단 초기에서부터 한계 상태까지 하중 단계에 따라서 이미지 해석을 수행하여 시료 내부의 변형을 측정하였다. 이를 바탕으로 전단면이 발생하기 시작하는 단계를 확인하였고, 이 단계부터 응력 연화 단계를 지나 한계 상태에 이를 때까지의 전단면의 특성을 기울기와 두께의 관점에서 평가하였다. 또한, 두께를 합리적으로 산정하기 위하여 통계적인 해석 절차도 마련하였다. Shear banding, the localization of deformation into thin zones, has a quite practical relevance, as stability and deformation characteristics of earth structures are controlled by the soil behavior within the shear band. In this study, for understanding occurrence and developed pattern of shear band, plane strain compression tests were performed on three soils with different particle-size distribution under various conditions. Digital images were captured during the experiments; then, deformation of a specimen was evaluated by digital image analysis technique. The characteristics of a shear band were evaluated from the state shortly after post-peak occurrence to critical state. Additionally, the statistical procedure was developed to determine the reasonable thickness of a shear band.

Comparison between two-fluid model simulations and particle image analysis & velocimetry (PIV) results for a two-dimensional gas–solid fluidized bed

This work compares simulation and experimental results of the hydrodynamics of a two-dimensional, bubbling air-fluidized bed. The simulation in this study has been conducted using an Eulerian–Eulerian two-fluid approach based on two different and well-known closure models for the gas–particle interaction: the drag models due to Gidaspow and Syamlal & O'Brien. The experimental results have been obtained by means of Digital Image Analysis (DIA) and Particle Image Velocimetry (PIV) techniques applied on a real bubbling fluidized bed of 0.005 m thickness to ensure its two-dimensional behaviour. Several results have been obtained in this work from both simulation and experiments and mutually compared. Previous studies in literature devoted to the comparison between two-fluid models and experiments are usually focused on bubble behaviour (i.e. bubble velocity and diameter) and dense-phase distribution. However, the present work examines and compares not only the bubble hydrodynamics and dense-phase probability within the bed, but also the time-averaged vertical and horizontal component of the dense-phase velocity, the air throughflow and the instantaneous interaction between bubbles and dense-phase. Besides, quantitative comparison of the time-averaged dense-phase probability as well as the velocity profiles at various distances from the distributor has been undertaken in this study by means of the definition of a discrepancy factor, which accounts for the quadratic difference between simulation and experiments The resulting comparison shows and acceptable resemblance between simulation and experiments for dense-phase probability, and good agreement for bubble diameter and velocity in two-dimensional beds, which is in harmony with other previous studies. However, regarding the time-averaged velocity of the dense-phase, the present study clearly reveals that simulation and experiments only agree qualitatively in the two-dimensional bed tested, the vertical component of the simulated dense-phase velocity being nearly an order of magnitude larger than the one obtained from the PIV experiments. This discrepancy increases with the height above the distributor of the two-dimensional bed, and it is even larger for the horizontal component of the time-averaged dense-phase velocity. In other words, the results presented in this work indicate that the fine agreement commonly encountered between simulated and real beds on bubble hydrodynamics is not a sufficient condition to ensure that the dense-phase velocity obtained with two-fluid models is similar to that from experimental measurements on two-dimensional beds.

Digital image analysis technique for mixing pattern measurements in Bi-dispersed 2D gas fluidized beds

This work concerns a new experimental technique based on Digital Image Analysis for the measurement of the mixing behaviour in a bi-dispersed 2D fluidized bed. Two different sets of particles are fluidized with the same density and different size. The technique is based on suitable color-field decomposition of the fluidized bed snapshots, where particles of different colors are employed. The technique here proposed can effectively measure the concentration field in the whole bed during operation and capture the mixing and segregation dynamics of powders. Notably, the technique here developed can be used for both gasor liquidfluidized beds.

Quantitative digital in situ senescence-associated β-galactosidase assay

BackgroundCellular senescence plays important roles in the aging process of complex organisms, in tumor suppression and in response to stress. Several markers can be used to identify senescent cells, of which the most widely used is the senescence-associated β-galactosidase (SABG) activity. The main advantage of SABG activity over other markers is the simplicity of the detection assay and the capacity to identify in situ a senescent cell in a heterogeneous cell population. Several approaches have been introduced to render the SABG assay quantitative. However none of these approaches to date has proven particularly amenable to quantitative analysis of SABG activity in situ. Furthermore the role of cellular senescence (CS) in vivo remains unclear mainly due to the ambiguity of current cellular markers in identifying CS of individual cells in tissues.ResultsIn the current study we applied a digital image analysis technique to the staining generated using the original SABG assay, and demonstrate that this analysis is highly reproducible and sensitive to subtle differences in staining intensities resulting from diverse cellular senescence pathways in culture. We have further validated our method on mouse kidney samples with and without diabetes mellitus, and show that a more accurate quantitative SABG activity with a wider range of values can be achieved at a pH lower than that used in the conventional SABG assay.ConclusionsWe conclude that quantitative in situ SABG assay, is feasible and reproducible and that the pH at which the reaction is performed should be tailored and chosen, depending on the research question and experimental system of interest.

Investigation of bubble behavior in fluidized beds with and without immersed horizontal tubes using a digital image analysis technique

Bubble characteristics such as shape, size, number and motion control the hydrodynamics and therefore heat transfer and chemical conversion in fluidized bed reactors. Thus understanding these characteristics is very important for the design and scale-up of fluidized beds. In this work a digital image analysis technique was developed to study the bubble behavior of two-dimensional bubbling beds with and without immersed horizontal tubes. Digital image analysis is a non-intrusive measurement technique which can simultaneously provide a great quantity of information without interfering with flow dynamics. The technique developed and implemented in this study allowed for the simultaneous measurement of various bubble properties, such as bubble diameter, rise velocity, aspect ratio and shape factor. A robust in-house code was developed to fully automate the image acquisition and data processing procedure. The experimental results obtained were validated and found to be in good agreement with available literature correlations. Moreover, based on the experimental results obtained new correlations for bubble growth and rise velocity as a function of bed height above the distributor were proposed. The models were in good agreement with the experimental data for a wide range of superficial velocities and particle sizes.

Spreading kinetics for quantifying cell state during stem cell differentiation

Major current problems in the stem cell field are how to determine the course of differentiation and how it is influenced by environmental factors. It would be very useful to be able to quantify the differentiation, not least because this would facilitate the discovery of correlations with quantitative environmental features. At present, optical microscopy is the main observational tool. Although it is easy to implement experimentally, quantitative analysis of the results is rather difficult, and some degree of subjectivity in the interpretation is almost inevitable. This paper explores a novel alternative approach to the problem, based on analysis of the rapid adaptive behavioral response of the cell to its arrival on a substratum, namely the transition from sphere to segment, which perturbs evanescent optical fields generated in the substratum and thereby can be monitored in a very straightforward fashion. Parameters characterizing the transition, which we hypothesize are characteristic of the state of differentiation of the cell, are readily extractable from the data. Spreading of a living cell in contact with the surface of a substratum is a basic response of the cell to such contact [1], although among the myriads of cell types and environments, the latter comprising both the nature of the substratum and of the liquid medium bathing cell and substratum, not all combinations thereof lead to spreading (see also, e.g., [2]). Furthermore, the actual temporal course of the spreading (i.e., its kinetics) depends sensitively on cell type and environment [1–4]: We hypothesize that these kinetics are a sensitive indicator of the spreading process. They would therefore be of practical use for identifying differentiation state provided that an appropriately accurate way of measuring them can be found. Our hypothesis is, then, that the rapid spreading1— quantitatively defined by the parameters of an appropriate mathematical function—is characteristic of the state of differentiation of an initially pluripotent stem cell. For the quantitative definition of spreading optical (e.g., [1]) or electron (e.g., [3]) microscopies are not really suitable, partly because of the difficulty of getting good time resolution (although modern techniques of digital photography and image analysis have overcome that to some extent) and partly because the information obtained is typically rather incomplete (e.g., just a cross section, i.e. either a plan or an elevation). Sometimes more complete information can be obtained, e.g. by using confocal microscopy, but mostly with an accompanying disadvantage, such as requiring the cell to be fed with a fluorescent dye, which may alter its physiology in unwanted ways; we note that stem cells are especially sensitive to foreign substances because of their pluripotency. Spreading kinetics for quantifying cell state during stem cell differentiation Amirreza Aref,†, ‡ Robert Horvath†, and Jeremy J. Ramsden†, *

Investigation of die drool phenomenon for HDPE polymer melt

In this work, the die drool phenomenon analysis has been performed for HDPE polymer melt by using a specific type of experimental set-up, digital image analysis technique and rheological tools. It has been revealed that the thermally induced degradation occurring inside the processing equipment may lead to HDPE melt elasticity enhancement, which promotes unwanted material accumulation at the end of the extrusion die.

Non-invasive method to quantify local bacterial concentrations in a mixed culture biofilm

To better engineer and analyze beneficial biofilms as well as to develop strategies to control detrimental biofilms (e.g., biomedical device-based infections), it is critical to quantify bacterial species compositions within biofilms. A non-invasive method is described here that determines local and overall bacterial concentrations within a biofilm, using optical microscopy and digital image analysis techniques. The method is based upon a calibration of cell fluorescence to known cell number concentrations and is verified by direct cell counts of destructive samples of cultivated biofilms. Two GFP mutants, each with unique emission colors were used with both epi-fluorescent microscopy and one-photon confocal microscopy to determine local spatial biofilm cell concentrations in pure and mixed-strain biofilms. Our microbial system comprises Pseudomonas putida containing either green fluorescent protein (GFP) or containing the red fluorescent protein (DsRed). Strains expressing a green or red fluorescent protein were detected by two different microscopy methods: epi-fluorescence and single-photon confocal laser scanning microscopy. Overall biofilm cell concentrations determined directly from destructive samples were in good agreement with non-invasive measurements of adherent cell concentrations calculated from the measured "integrated fluorescent density" minus any background fluorescence. Results show the areal cell concentration (cell number/area) determined from non-destructive direct counts in a pure culture or binary-strain biofilm varied with the biofilm depth. Use of this method to estimate local dynamic plasmid segregational loss and plasmid conjugation transfer kinetics will be reported in a subsequent manuscript.

Análise morfométrica do colágeno dérmico a partir da segmentação por conglomerados (clusters) de cor

Morphometric analysis of dermal collagen can provide quantitative support to dermatologic research. The authors of this article disclose a technique of digital image analysis which allows the identification of microscopic structures by color cluster segmentation regarding the estimate intensity and density of dermal collagen fibers.