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.

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.

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).

Image formation analysis of thick biological specimens using three-dimensional power-spectra of through focus series

1994 ◽  
Vol 52 ◽  
pp. 124-125
Author(s):  
Karen F. Han
Keyword(s):  
Inelastic Scattering ◽  
Imaging Techniques ◽  
Mass Density ◽  
Relative Proportion ◽  
Three Dimensional ◽  
Power Spectra ◽  
Image Formation ◽  
Energy Filtering ◽  
Ewald Sphere ◽  
Nonlinear Imaging

The primary focus in our laboratory is the study of higher order chromatin structure using three dimensional electron microscope tomography. Three dimensional tomography involves the deconstruction of an object by combining multiple projection views of the object at different tilt angles, image intensities are not always accurate representations of the projected object mass density, due to the effects of electron-specimen interactions and microscope lens aberrations. Therefore, an understanding of the mechanism of image formation is important for interpreting the images. The image formation for thick biological specimens has been analyzed by using both energy filtering and Ewald sphere constructions. Surprisingly, there is a significant amount of coherent transfer for our thick specimens. The relative amount of coherent transfer is correlated with the relative proportion of elastically scattered electrons using electron energy loss spectoscopy and imaging techniques.Electron-specimen interactions include single and multiple, elastic and inelastic scattering. Multiple and inelastic scattering events give rise to nonlinear imaging effects which complicates the interpretation of collected images.

Cardiovascular Imaging for Guiding Interventional Therapy in Structural Heart Diseases

2020 ◽  
Vol 16 (2) ◽  
pp. 111-122
Author(s):  
Nora Rat ◽  
Iolanda Muntean ◽  
Diana Opincariu ◽  
Liliana Gozar ◽  
Rodica Togănel ◽  
...  
Keyword(s):  
Heart Diseases ◽  
Interventional Procedure ◽  
Imaging Techniques ◽  
Ductus Arteriosus ◽  
Three Dimensional ◽  
High Specificity ◽  
Interventional Therapy ◽  
Structural Defects ◽  
Imaging Method ◽  
Three Dimensional Echocardiography

Development of interventional methods has revolutionized the treatment of structural cardiac diseases. Given the complexity of structural interventions and the anatomical variability of various structural defects, novel imaging techniques have been implemented in the current clinical practice for guiding the interventional procedure and for selection of the device to be used. Three– dimensional echocardiography is the most used imaging method that has improved the threedimensional assessment of cardiac structures, and it has considerably reduced the cost of complications derived from malalignment of interventional devices. Assessment of cardiac structures with the use of angiography holds the advantage of providing images in real time, but it does not allow an anatomical description. Transesophageal Echocardiography (TEE) and intracardiac ultrasonography play major roles in guiding Atrial Septal Defect (ASD) or Patent Foramen Ovale (PFO) closure and device follow-up, while TEE is the procedure of choice to assess the flow in the Left Atrial Appendage (LAA) and the embolic risk associated with a decreased flow. On the other hand, contrast CT and MRI have high specificity for providing a detailed description of structure, but cannot assess the flow through the shunt or the valvular mobility. This review aims to present the role of modern imaging techniques in pre-procedural assessment and intraprocedural guiding of structural percutaneous interventions performed to close an ASD, a PFO, an LAA or a patent ductus arteriosus.

scholarly journals Gynecology Meets Big Data in the Disruptive Innovation Medical Era: State-of-Art and Future Prospects

2021 ◽  
Vol 18 (10) ◽  
pp. 5058
Author(s):  
Rola Khamisy-Farah ◽  
Leonardo B. Furstenau ◽  
Jude Dzevela Kong ◽  
Jianhong Wu ◽  
Nicola Luigi Bragazzi
Keyword(s):  
Big Data ◽  
Information And Communication Technologies ◽  
Imaging Techniques ◽  
Treatment Options ◽  
Wearable Sensors ◽  
Three Dimensional ◽  
Disruptive Innovation ◽  
Healthcare Management ◽  
The Internet ◽  
Big Data Visualization

Tremendous scientific and technological achievements have been revolutionizing the current medical era, changing the way in which physicians practice their profession and deliver healthcare provisions. This is due to the convergence of various advancements related to digitalization and the use of information and communication technologies (ICTs)—ranging from the internet of things (IoT) and the internet of medical things (IoMT) to the fields of robotics, virtual and augmented reality, and massively parallel and cloud computing. Further progress has been made in the fields of addictive manufacturing and three-dimensional (3D) printing, sophisticated statistical tools such as big data visualization and analytics (BDVA) and artificial intelligence (AI), the use of mobile and smartphone applications (apps), remote monitoring and wearable sensors, and e-learning, among others. Within this new conceptual framework, big data represents a massive set of data characterized by different properties and features. These can be categorized both from a quantitative and qualitative standpoint, and include data generated from wet-lab and microarrays (molecular big data), databases and registries (clinical/computational big data), imaging techniques (such as radiomics, imaging big data) and web searches (the so-called infodemiology, digital big data). The present review aims to show how big and smart data can revolutionize gynecology by shedding light on female reproductive health, both in terms of physiology and pathophysiology. More specifically, they appear to have potential uses in the field of gynecology to increase its accuracy and precision, stratify patients, provide opportunities for personalized treatment options rather than delivering a package of “one-size-fits-it-all” healthcare management provisions, and enhance its effectiveness at each stage (health promotion, prevention, diagnosis, prognosis, and therapeutics).

Prenatal Diagnosis

1992 ◽  
Vol 13 (9) ◽  
pp. 334-342
Author(s):  
John H. DiLiberti ◽  
Mark A. Greenstein ◽  
Sally Shulman Rosengren
Keyword(s):  
Prenatal Diagnosis ◽  
Imaging Techniques ◽  
Three Dimensional ◽  
Prenatal Testing ◽  
The Past ◽  
Computerized Image Processing ◽  
The Family ◽  
Family History Assessment ◽  
Additional Explanation ◽  
Pediatric Disorders

The enormous progress witnessed in the field of prenatal diagnosis during the past two decades is likely to continue into the future. Improved imaging techniques are likely to enhance the resolution of noninvasively obtained fetal images considerably over their current excellent quality. Although this undoubtedly will be true for ultrasonography, the increased speed of magnetic resonance equipment may offer a new realm of imaging possibilities. Computerized image processing, analysis, and three-dimensional reconstructions all should make interpretation of fetal images easier and more understandable to the nonspecialist. Advances in molecular genetics will continue to accelerate, greatly expanding the range and accuracy of prenatal diagnosis. The alert pediatrician who is sensitive to genetic issues may, by early detection of pediatric disorders and careful family history assessment, be in a position to identify families at risk for serious genetic conditions and provide the opportunity to make informed decisions on reproductive options that avert a major tragedy. The pediatrician, working with obstetric colleagues, should be part of a team effort to support families going through prenatal testing. Familiarity with these rapidly changing technologies will make it far easier to support the family needing additional explanation about prenatal diagnosis issues.

scholarly journals Full-field imaging of thermal and acoustic dynamics in an individual nanostructure using tabletop high harmonic beams

2018 ◽  
Vol 4 (10) ◽  
pp. eaau4295 ◽  
Author(s):  
Robert M. Karl ◽  
Giulia F. Mancini ◽  
Joshua L. Knobloch ◽  
Travis D. Frazer ◽  
Jorge N. Hernandez-Charpak ◽  
...  
Keyword(s):  
Functional Imaging ◽  
Extreme Ultraviolet ◽  
Imaging Techniques ◽  
High Harmonic ◽  
Three Dimensional ◽  
Dynamic Imaging ◽  
Significant Advance ◽  
Grand Challenge ◽  
Diffractive Imaging ◽  
Full Field

Imaging charge, spin, and energy flow in materials is a current grand challenge that is relevant to a host of nanoenhanced systems, including thermoelectric, photovoltaic, electronic, and spin devices. Ultrafast coherent x-ray sources enable functional imaging on nanometer length and femtosecond timescales particularly when combined with advances in coherent imaging techniques. Here, we combine ptychographic coherent diffractive imaging with an extreme ultraviolet high harmonic light source to directly visualize the complex thermal and acoustic response of an individual nanoscale antenna after impulsive heating by a femtosecond laser. We directly image the deformations induced in both the nickel tapered nanoantenna and the silicon substrate and see the lowest-order generalized Lamb wave that is partially confined to a uniform nanoantenna. The resolution achieved—sub–100 nm transverse and 0.5-Å axial spatial resolution, combined with ≈10-fs temporal resolution—represents a significant advance in full-field dynamic imaging capabilities. The tapered nanoantenna is sufficiently complex that a full simulation of the dynamic response would require enormous computational power. We therefore use our data to benchmark approximate models and achieve excellent agreement between theory and experiment. In the future, this work will enable three-dimensional functional imaging of opaque materials and nanostructures that are sufficiently complex that their functional properties cannot be predicted.

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