Characterising the aggregate structure variations in asphalt concrete during compaction using computer automated imaging techniques

2007 ◽  
Vol 28 (4) ◽  
pp. 295
Author(s):  
Kasthurirangan Gopalakrishnan ◽  
Naga Shashidhar
Keyword(s):  
Asphalt Concrete ◽  
Imaging Techniques ◽  
Aggregate Structure ◽  
Automated Imaging

Computer Simulation of Particle Packing In Bituminous Concrete

2009 ◽  
pp. 243-260
Author(s):  
Kasthurirangan Gopalakrishnan ◽  
Naga Shashidhar
Keyword(s):  
Computer Simulation ◽  
Asphalt Concrete ◽  
Hard Spheres ◽  
Imaging Techniques ◽  
Particle Packing ◽  
Asphalt Pavements ◽  
Portland Cement Concrete ◽  
Particle Size Range ◽  
Aggregate Structure ◽  
Nondestructive Imaging

Although computer simulation methods have been used extensively in modeling the microstructure of Portland cement concrete, their application for studying asphalt concrete is relatively new. In this chapter, the nature and distribution of inter-particle contacts in computer-simulated compacts with a wide particle size range such as those found in asphalt pavements are discussed. The aggregates were modeled as hard spheres and some typical aggregate gradations used in AC were packed using a computer program. The application of particle packing simulation concepts discussed in this chapter to the study of aggregate structure in asphalt pavements, in conjunction with the recent advances in nondestructive imaging techniques and DEM simulations have tremendous potential to help us to develop a deeper understanding of the aggregate structure in asphalt concrete, develop and optimize the various parameters that describe the aggregate structure and relate them to the performance of pavements in a scientific way.

scholarly journals Automated Selection of DAB-labeled Tissue for Immunohistochemical Quantification

2003 ◽  
Vol 51 (5) ◽  
pp. 575-584 ◽  
Author(s):  
Eric M. Brey ◽  
Zahid Lalani ◽  
Carol Johnston ◽  
Mark Wong ◽  
Larry V. McIntire ◽  
...  
Keyword(s):  
Imaging Technique ◽  
Imaging Techniques ◽  
Basic Research ◽  
Quantitative Information ◽  
Automated Identification ◽  
Clinical Tool ◽  
Protein Levels ◽  
Diagnosis And Prognosis ◽  
Automated Imaging ◽  
Selection Of

The increased use of immunohistochemistry (IHC) in both clinical and basic research settings has led to the development of techniques for acquiring quantitative information from immunostains. Staining correlates with absolute protein levels and has been investigated as a clinical tool for patient diagnosis and prognosis. For these reasons, automated imaging methods have been developed in an attempt to standardize IHC analysis. We propose a novel imaging technique in which brightfield images of diaminobenzidene (DAB)-labeled antigens are converted to normalized blue images, allowing automated identification of positively stained tissue. A statistical analysis compared our method with seven previously published imaging techniques by measuring each one's agreement with manual analysis by two observers. Eighteen DAB-stained images showing a range of protein levels were used. Accuracy was assessed by calculating the percentage of pixels misclassified using each technique compared with a manual standard. Bland-Altman analysis was then used to show the extent to which misclassification affected staining quantification. Many of the techniques were inconsistent in classifying DAB staining due to background interference, but our method was statistically the most accurate and consistent across all staining levels.

Evaluating the aggregate structure in hot-mix asphalt using three-dimensional computer modeling and particle packing simulations

2006 ◽  
Vol 33 (8) ◽  
pp. 945-954 ◽  
Author(s):  
Naga Shashidhar ◽  
Kasthurirangan Gopalakrishnan
Keyword(s):  
Hot Mix Asphalt ◽  
Imaging Techniques ◽  
Three Dimensional ◽  
Packing Fraction ◽  
Particle Packing ◽  
Minimum Size ◽  
Discrete Element Modeling ◽  
Void Space ◽  
Aggregate Structure ◽  
Pavement Distresses

In a hot-mix asphalt (HMA) pavement, the aggregate structure serves as a backbone and is primarily responsible for resisting pavement distresses. A sound aggregate structure implies optimal packing of aggregates providing both particle–particle contact and sufficient void space to fill in asphalt. In this paper, three-dimensional particle packing concepts are applied to the study of aggregate structure in HMA. A sequential deposition packing algorithm was used for packing typical aggregate gradations. The packing fraction and the distribution of particle–particle contacts in the simulated compact were studied. The packing simulation gave satisfactory results when aggregates above a certain minimum size were considered. Regression models were established to estimate the coordination number of any size aggregate in the compact. Such studies, in conjunction with the recent advances in X-ray computed tomography imaging techniques and discrete element modeling (DEM) simulations, have tremendous potential to help develop a deeper understanding of the HMA aggregate structure, develop and optimize the various parameters that describe the aggregate structure, and relate these parameters to the performance of pavements in a scientific way.Key words: packing, aggregate structure, computer simulation, aggregate–aggregate contact, pavement performance.

Mitochondrial Reconstructions Based on Serial Thick Sections and HVEM

1975 ◽  
Vol 33 ◽  
pp. 286-287
Author(s):  
Jerome J. Paulin
Keyword(s):  
Imaging Techniques ◽  
Three Dimensional ◽  
Posterior Pole ◽  
Dimensional Structure ◽  
Stereo Imaging ◽  
Thin Sections ◽  
Anatomical Features ◽  
The Past ◽  
Cellular Components ◽  
Mitochondrial Reticulum

Within the past decade it has become apparent that HVEM offers the biologist a means to explore the three-dimensional structure of cells and/or organelles. Stereo-imaging of thick sections (e.g. 0.25-10 μm) not only reveals anatomical features of cellular components, but also reduces errors of interpretation associated with overlap of structures seen in thick sections. Concomitant with stereo-imaging techniques conventional serial Sectioning methods developed with thin sections have been adopted to serial thick sections (≥ 0.25 μm). Three-dimensional reconstructions of the chondriome of several species of trypanosomatid flagellates have been made from tracings of mitochondrial profiles on cellulose acetate sheets. The sheets are flooded with acetone, gluing them together, and the model sawed from the composite and redrawn.The extensive mitochondrial reticulum can be seen in consecutive thick sections of (0.25 μm thick) Crithidia fasciculata (Figs. 1-2). Profiles of the mitochondrion are distinguishable from the anterior apex of the cell (small arrow, Fig. 1) to the posterior pole (small arrow, Fig. 2).

Application of Lattice Imaging Techniques to Amorphous Films

1975 ◽  
Vol 33 ◽  
pp. 8-9
Author(s):  
S. R. Herd ◽  
P. Chaudhari
Keyword(s):  
Nearest Neighbor ◽  
Random Network ◽  
Imaging Techniques ◽  
Network Models ◽  
Accurate Method ◽  
Direct Transmission ◽  
Lattice Imaging ◽  
Transmission Electron ◽  
Lattice Planes ◽  
Nearest Neighbor Distances

Electron diffraction and direct transmission have been used extensively to study the local atomic arrangement in amorphous solids and in particular Ge. Nearest neighbor distances had been calculated from E.D. profiles and the results have been interpreted in terms of the microcrystalline or the random network models. Direct transmission electron microscopy appears the most direct and accurate method to resolve this issue since the spacial resolution of the better instruments are of the order of 3Å. In particular the tilted beam interference method is used regularly to show fringes corresponding to 1.5 to 3Å lattice planes in crystals as resolution tests.

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